Sedimentary environmental quality of a biosphere reserve estuary in southwestern Iberian Peninsula

The Huelva estuary is formed by the common mouths of the Odiel and Tinto Rivers, and inside this ecosystem is the biosphere reserve of the Odiel saltmarshes. This ecosystem has been historically affected by acid mine drainage (AMD) and by releases of pollutants from five phosphoric acid industrial plants and phosphogypsum (PG) waste stacks located in the area. This study carried out a comprehensive assessment of the environmental impact of the biosphere reserve of the Odiel saltmarshes. To this end, it was necessary to find a suitable sedimentary background (Piedras River in our case). To quantify this impact, several pollution indexes were used. According to the values reached by the indexes, this impact was classified as "serious" pollution for most trace elements, excepting the deepest layers, and "low-moderate" pollution for the 238U-series radionuclides, while no pollution for the 232Th-series and 40K radionuclides was found as expected.

Guidelines for inhaled sedation in the ICU

INTRODUCTION AND OBJECTIVES

Sedation is used in intensive care units (ICU) to improve comfort and tolerance during mechanical ventilation, invasive interventions, and nursing care. In recent years, the use of inhalation anaesthetics for this purpose has increased. Our objective was to obtain and summarise the best evidence on inhaled sedation in adult patients in the ICU, and use this to help physicians choose the most appropriate approach in terms of the impact of sedation on clinical outcomes and the risk-benefit of the chosen strategy.

METHODOLOGY

Given the overall lack of literature and scientific evidence on various aspects of inhaled sedation in the ICU, we decided to use a Delphi method to achieve consensus among a group of 17 expert panellists. The processes was conducted over a 12-month period between 2022 and 2023, and followed the recommendations of the CREDES guidelines.

RESULTS

The results of the Delphi survey form the basis of these 39 recommendations - 23 with a strong consensus and 15 with a weak consensus.

CONCLUSION

The use of inhaled sedation in the ICU is a reliable and appropriate option in a wide variety of clinical scenarios. However, there are numerous aspects of the technique that require further study.

Tracheostomy Patient Care Unit. An innovative Otorhinolaryngology solution of a transversal nature for the hospital

BACKGROUND AND OBJECTIVE

The care of tracheostomized patients are high risk skills and low incidence. Strategies for improvement of health care in hospital wards and specialties other than otolaryngology based solely on training have not been able to offer an adequate solution. A tracheostomized patient unit is presented directed by the otolaryngology service to attend all tracheostomized hospitalized patients of all specialties.

MATERIAL AND METHODS

Background: Third level public hospital with 876 hospitalization beds and 30 ICU beds for 481,296 inhabitants. Unit model: Transversal unit for the hospital providing attention to all tracheostomized patients, adults, and children, of all specialties, with dedication of 50 % of a ENT nurse of hospitalization that moves to the hospitalization bed of the specialty of each patient and 50 % of another office ENT nurse for ambulatory patients care, with the consultancy of an ENT specialist and coordinated by the ENT supervisor.

RESULTS

572 patients between 2016 and 2021, 80% men, aged 63 ± 14 years, were attended in the Unit. 14.7 ± 2 tracheostomized patients daily and 96 ± 4 complication annual consultations were attended, rising up to 19 tracheostomized patients daily by 2020 and 141 ± 8.4 consultations by complications in 2020 and 2021, during the COVID-19 pandemic. The mean stay of the non-ENT specialties was reduced in 13 days, increasing the satisfaction of the ENT and non-ENT professionals and the satisfaction of the users.

CONCLUSIONS

A Tracheostomized Patient Care Unit proactively directed from the Otorhinolaryngology Service to transversally care for all tracheostomized patients improves the quality of health care by reducing stay, complications, and emergencies. Improves the satisfaction of non-otolaryngological professionals by reducing the anxiety of facing care of patients who lack knowledge and experience and that of ENT specialists and nurses by reducing unplanned extemporaneous demands for care. Improves user satisfaction by perceiving adequate continuity of care. The Otorhinolaryngology Services provide their experience in the management of laryngectomized and tracheostomized patients and in teamwork with other specialists and professionals without the need to create new structures outside otorhinolaryngology.

Spatiotemporal evolution of U and Th isotopes in a mine effluent highly polluted by Acid Mine Drainage (AMD)

The spatiotemporal evolution of both U and Th isotopes in a mine effluent highly polluted by acid mine drainage (AMD) was evaluated. The acidic tributary, which born from the outflows of an abandoned sulfide mine, flows into the Odiel River. AMD comprises an important source of natural radionuclides, presenting concentrations of ²³⁸U and ²³²Th, two and four orders of magnitude higher, respectively, than the background values of surface continental waters. These natural radionuclides behave conservatively along the mine effluent (pH < 2.5) throughout the hydrological year. Under AMD conditions uranium is in the hexavalent state U(VI) and the main dissolved species are uranyl sulfate complexes. The polluted tributary has a significant impact on the Odiel River acidifying its waters during the low flow season and increasing up to one order of magnitude the activity concentrations of U and Th isotopes. U presented a conservative behavior in the Odiel River during the low flow season (pH ≈ 3), however it is removed from the liquid phase in the wet season (pH ≈ 6), probably due its coprecipitation/adsorption onto Al-phases. Th shows a high sensitivity to small increases of pH, and it is strongly coprecipitated/adsorbed with or onto Fe-oxyhydroxydizes in the river.

P-150 TRANSVERSUS ABDOMINIS RELEASE BY MINIMAL INVASIVE SURGERY. OUR EXPERIENCE IN A TERCIARY HOSPITAL

Aim

We present the experience in the transversus abdominis release (TAR) technique using a minimally invasive approach in our center.

Methods

We expose those W3 defects intervened by laparoscopic TAR(n=6). Step 1:

Releasing adhesions from previous surgeries. Step 2: Bilateral Rives space dissection, as well as the Rossen's space, this one using “down to up” technique. Step 3: Closure of the gap with barbed suture. In all cases, a PVDF mesh has been associated with atraumatic fixation, and 2 drains were placed.

Results

The mean age was 62, 100% men, and their BMI was greater than 25Kg/m2. All underwent scheduled surgery, using a minimally invasive approach, placing the mesh at the retromuscular level. Postoperative stay was 7.6 days. We did not obtain major complications (perforation, bleeding), but a drainage hole wound infection was registered. We had no readmissions or any medical complications.

Follow-up of 12 months, without signs of recurrence or chronic pain.

Conclusions

Although Robotic surgery and Botulinum toxin in surgery seems to be the future, in our experience TAR technique performed by laparoscopy is useful for large midline incisional hernias treatment as well as those associated with a lateral component in a terciary Hospital. We obtain good results in terms of recurrence and restoration of the abdominal wall dynamics. However, further studies are necessary to be carried out by experienced teams to reach conclusions.

OC-066 LIRA TECHNIQUE, A NEW PROCEDURE. WHERE ARE WE NOW? OUR RESULTS IN A MEDIUM FOLLOW-UP

Background

LIRA technique (Laparoscopic Intracorporeal Rectus Aponeuroplasty) was described in 2018 in order to reduce the tension in the midline as an alternative to defect closure (CD) in Laparoscopic Ventral Hernia Repair. We present our results in LIRA series in patients with a medium follow up

Methods

A prospective controlled study from January 2015 to December 2020 to evaluate (LIRA) performed on patients with midline w2 hernias (EHS Classification). Data analyzed included patient demographics, operative parameters and complications.

Tomography was performed preoperatively and postoperatively (1 month and 1 year) to evaluate recurrence, distance between rectus and seroma. Clinical examination were performed yearly.

Results

49 patients. Mean Age was 58± 10.59 years old and BMI 33.11± 6.61 kg/m2. Mean width of the defect was 6.19± 1.49 cm. Average VAS (24 h) was 5.09 ± 5, 0.38(1 month) and 0 (1 year). Mean preoperative distance between rectus was 5.55± 1.61 cm; postoperative was 2.15 ± 0.79 cm (1 month) and 2.20±0.68 cm (1 year). Radiological seroma at first month was detected in 40%. Seroma after 1 year was 4,08% Mean follow-up was 24 months. Bulging detected only in 1 case (2.04%) after 1 year follow up. No recurrence is data.

Conclusion

LIRA technique could be considered as an alternative to CD for w2 defects with a low rate of complication, and could be related to a low rate of postoperative pain with no recurrence and a low rate of bulging compared to CD, being a safe, feasible and reproducible technique.

V-043 NEW CONCEPTS IN LIRA TECHNIQUE IN LAPAROSCOPIC VENTRAL HERNIA REPAIR. LIRA -LESS STEP BY STEP

Introduction

LIRA (Laparoscopic Intracorporeal Rectus Aponeuroplasty) described in 2018 by our group showed advantages in preliminary results in terms of recurrence and bulging because a reduced tension in the midline in W2 defects following the EHS Classification. Otherwise permanent fixation in inlay meshes is related with and increase of pain and adhesions. We present LIRA-LESS step to step as an evolution in LIRA technique.

Material and methods

A 58 years old male affected by a M3W2 hernia. A LIRA procedure is proposed.

Step 1: adhesions release and sac content reduced.

Step 2: defect measurement and flap designed following the LIRA Technique principles with the neumoperitoneum deflated and flap mobilized and suture in the midline.

Step 3 An in lay mesh of PVDF is positioned reducing permanent fixation in cardinal points combined with Cianocrilate in a 3:1 way.

Step 4 A TAP-block anesthesia is performed in this case with Ropivacaine 2%.

Results

Operative time was 95 min. VAS 1 day was 3 and was discharge without complications. VAS 7 day in clinical office was 0. There were not recurrence or Bulkging in CT -Scan 1 month after the surgery.

Discussion

LIRA technique is a safe procedure with a low tension in the midline with good reults in terms of recurrence and bulging. LIRA-LESS concept allows a reduction in traumatic permanent fixation with good results in terms of pain and recurrence.

Radon transport events associated with the impact of a NORM repository in the SW of Europe

Two radon measurement stations located to the north and south of a NORM (Naturally Occurring Radioactive Materials) repository of phosphogypsum (southwest of Europe) were used to monitor radon behavior during 2018. The stations are located at opposing sides of the repository, one in Huelva City to the north and other one in a rural area to the south. This setup aimed to identify the influence of the NORM repository on each station and use radon levels as a marker of atmospheric transport in the local area. To achieve this, a comparison was carried out with other coastal stations in the south of Spain, finding higher average concentrations in Huelva City, ~3.3 Bq m^-3. Hierarchical clustering was applied to identify days with different radon patterns at each Huelva station, detecting possible local radon transport events from the repository. Three events were investigated with WRF (Weather Research and Forecasting) and FLEXPART-WRF (FLEXible PARTicle dispersion model). It was found that both sampling sites required atmospheric stagnant conditions to reach high radon concentration. However, under these conditions the urban station showed high radon regardless of wind direction while the rural station also required radon transport from the repository, either directly or indirectly.

Arsenic removal procedure for the electrolyte from a hydro-pyrometallurgical complex

Commercial copper (Cu) is obtained by a hydro-pyrometallurgical process, where the Cu anodes obtained in the furnaces (Cu > 99.5%) are enriched up to 99.99% in "cathodes" by electrorefining at an electrolysis plant. During this process, some impurities accumulate in the electrolyte, mainly arsenic (As), which decrease the quality of the Cu cathode. For this reason, the electrolyte is sent to an electrolyte cleaning plant (ECP) for its purification. Electrolyte sludge (ES) is produced in the last stage of purification and is recirculated back to the furnace due to the high Cu content. This recirculation involves a severe problem of As accumulation in the industrial process. The objective of this work was to develop a procedure to fully dissolve the ES, removing the As and recovering its Cu content. The ES dissolution process was optimised (dissolution efficiency > 99%) in H₂SO₄ (1.4 M)/HNO₃ (1.8 M) medium using a 1:20 g mL^-1 solid-to-liquid ratio. As was removed from the ES solution by its precipitation as iron (III) arsenate, with high efficiency (more than 70%). After As removal, the Cu can be precipitated as copper sulphate, which is used in several applications.

Behaviour of heavy metals and natural radionuclides in the mixing of phosphogypsum leachates with seawater

Phosphogypsum (PG) is disposed worldwide in large stacks usually placed in coastal zones, as in the case of Huelva (SW of Spain), where around 100 Mt of PG are stored on the salt marshes of the Tinto River estuary covering a surface of about 1000 ha. This management generates the weathering of PG, and due to its high acidity (pH ≈ 2) and pollutant load can provoke significant emissions into their surroundings. In this work were evaluated by laboratory experiments the effects of pH increase in the behaviour of heavy metals and natural radionuclides during the mixing of phosphogypsum leachates with seawater. The acidic phosphogypsum leachates showed concentrations of heavy metals from two to three orders of magnitude higher than natural continental waters, and natural radionuclides (U-isotopes and ²¹⁰Po) from four to five orders of magnitude higher than unperturbed aquatic systems. Major elements and some heavy metals as Mn, Ni, Cd, As, Sb and Co showed a conservative behaviour during the neutralisation of the leachates with seawater, remaining in the liquid phase, while other ones as Al, Fe, Cr, Zn, Cu, Pb precipitated and/or were adsorbed onto the solid phase. The U-isotopes and ²¹⁰Po showed a clear non-conservative behaviour probably due to coprecipitation/adsorption processes onto the formed precipitates, but while ²¹⁰Po reached a total removal at pH ≈ 7, U- isotopes after a total removal at pH ≈ 5 returned into the liquid phase due to redissolution/desorption processes at near neutral pH. The formed precipitates, mainly composed by iron phosphates particles, showed heavy metal and natural radionuclide concentrations from one to three orders of magnitude higher than unperturbed soils. All these facts demonstrate the serious environmental impact produced by the PG stacks into their surroundings and the urgency of effective restoration measures.

Radiological and physico-chemical characterization of materials from phosphoric acid production plant to assess the workers radiological risks

The industry devoted to the production of phosphoric acid by using as raw material sedimentary phosphate rock (PR) is considered as a NORM activity (Naturally Occurring Radioactive Materials), due to the high levels of U-series radionuclides contained in this ore, which are 1-2 orders of magnitude higher than those in unperturbed soils. This fact allowed us to develop a deep characterization of the raw materials, wastes, main intermediate materials, and final products obtained at a typical phosphoric acid factory. The elemental composition (major, minor and trace elements), radionuclide concentrations, grain size distribution, mineralogy and micro-structural composition were analyzed. The aim of this characterization was to obtain information for operators and maintenance personnel involved in clean-up and waste management operations. The highest concentrations of some heavy metals and radionuclide activity concentrations were found in the "scales" (or internal incrustations)from the pipes that carry either phosphoric acid (PA) or the phosphogypsum waste (PG). The highest concentrations where found for ²²⁶Ra and ⁴⁰K,with values up to 9 and 5 Bq g^-1, respectively. In addition, high concentrations of many toxic heavy metals and trace elements, such as Cd, Cr, Ni, Sr, Y, V, Zn, Th, and U, were found in some sludge samples. The shielding effect of the containers/vessels/pipes has an essential role in the measured external dose in the intermediate products. The radiological implications of natural radionuclides with higher activity showed that if the maximum particulate matter concentration established in the Spanish regulation is verified, and taking into account the most conservative scenario, the annual limit of 1 mSv y^-1 is not exceeded.

Influence of the accumulation chamber insertion depth to measure surface radon exhalation rates

A common method to measure radon exhalation rates relies on the accumulation chamber technique. Usually, this approach only considers one-dimensional gas transport within the soil that neglects lateral diffusion. However, this lateral transport could reduce the reliability of the method. In this work, several cylindrical-shaped accumulation chambers were built with different heights to test if the insertion depth of the chamber into the soil improves the reliability of the method and, in that case, if it could limit the radon lateral diffusion effects. To check this hypothesis in laboratory, two reference exhalation boxes were manufactured using phosphogypsum from a repository located nearby the city of Huelva, in the southwest of Spain. Laboratory experiments showed that insertion depth had a deep impact in reducing the effective decay constant of the system, extending the interval where the linear fitting can be applied, and consistently obtaining reliable exhalation measurements once a minimum insertion depth is employed. Field experiments carried out in the phosphogypsum repository showed that increasing the insertion depth could reduce the influence of external effects, increasing the repeatability of the method. These experiments provided a method to obtain consistent radon exhalation measurements over the phosphogypsum repository.

Sphenopalatine Ganglion Stimulation to Augment Cerebral Blood Flow

Background and Purpose—

Many patients with acute ischemic stroke are not eligible for thrombolysis or mechanical reperfusion therapies due to contraindications, inaccessible vascular occlusions, late presentation, or large infarct core. Sphenopalatine ganglion (SPG) stimulation to enhance collateral flow and stabilize the blood-brain barrier offers an alternative, potentially more widely deliverable, therapy.

Methods—

In a randomized, sham-controlled, double-masked trial at 41 centers in 7 countries, patients with anterior circulation ischemic stroke not treated with reperfusion therapies within 24 hours of onset were randomly allocated to active SPG stimulation or sham control. The primary efficacy outcome was improvement beyond expectations on the modified Rankin Scale of global disability at 90 days (sliding dichotomy), assessed in the modified intention-to-treat population. The initial planned sample size was 660 patients, but the trial was stopped early when technical improvements in device placement occurred, so that analysis of accumulated experience could be conducted to inform a successor trial.

Results—

Among 303 enrolled patients, 253 received at least one active SPG or sham stimulation, constituting the modified intention-to-treat population (153 SPG stimulation and 100 sham control). Age was median 73 years (interquartile range, 64–79), 52.6% were female, deficit severity on the National Institutes of Health Stroke Scale was median 11 (interquartile range, 9–15), and time from last known well median 18.6 hours (interquartile range, 14.5–22.5). For the primary outcome, improved 3-month disability beyond expectations, rates in the SPG versus sham treatment groups were 49.7% versus 40.0%; odds ratio, 1.48 (95% CI, 0.89–2.47); P =0.13. A significant treatment interaction with stroke location (cortical versus noncortical) was noted, P =0.04. In the 87 patients with confirmed cortical involvement, rates of improvement beyond expectations were 50.0% versus 27.0%; odds ratio, 2.70 (95% CI, 1.08–6.73); P =0.03. Similar response patterns were observed for all prespecified secondary efficacy outcomes. No differences in mortality or serious adverse event safety end points were observed.

Conclusions—

SPG stimulation within 24 hours of onset is safe in acute ischemic stroke. SPG stimulation was not shown to statistically significantly improve 3-month disability above expectations, though favorable outcomes were nominally higher with SPG stimulation. Beneficial effects may distinctively be conferred in patients with confirmed cortical involvement. The results of this study need to be confirmed in a larger pivotal study.

Clinical Trial Registration—

URL: https://www.clinicaltrials.gov . Unique identifier: NCT03767192.

Clinical protocol for the management of malignant hyperthermia

Malignant hyperthermia is a hypermetabolic syndrome that appears in susceptible patients after exposure to certain anaesthetic drugs (succinylcholine, inhalation anaesthetics). Its incidence in Spain is 1 in 40,000 adults, with a 10% mortality rate. It is induced by an abnormal regulation of the ryanodine receptors, producing a massive release of calcium from the sarcoplasmic reticulum in the striate muscle. Clinical manifestations include: CO₂ increase, tachycardia, haemodynamic instability, metabolic and respiratory acidosis, profuse sweating, hyperpyrexia, CPK increase, myoglobinuria, kidney failure, disseminated intravascular coagulation (DIC), and ending in cardiac arrest. Dantrolene sodium is a ryanodine receptor antagonist, and inhibits the release of intracellular calcium. Definitive diagnosis is achieved by the exposure of muscle fibres to caffeine and halothane. Protocols can help guarantee a reliable and secure management when this severe event occurs.

Multiple strains of Coxiella burnetii are present in the environment of St. Paul Island, Alaska

In 2010, Coxiella burnetii was identified at a high prevalence in the placentas of Northern fur seals (Callorhinus ursinus) collected at a single rookery on St. Paul Island Alaska; an area of the United States where the agent was not known to be present. As contamination was hypothesized as a potential cause of false positives, but nothing was known about environmental C. burnetii in the region, an environmental survey was conducted to look for the prevalence and distribution of the organism on the island. While environmental prevalence was low, two strains of the organism were identified using PCR targeting the COM1 and IS1111 genes. The two strains are consistent with the organism that has been increasingly identified in marine mammals as well as a strain type more commonly found in terrestrial environments and associated with disease in humans and terrestrial animals. Further work is needed to elucidate information regarding the ecology of this organism in this region, particularly in association with the coastal environment.

Voiding dysfunction: another etiology of vulvovaginitis in young girls

OBJECTIVE

To determine the prevalence of voiding dysfunction (VD) in patients with persistent vulvovaginitis (PVV), and to evaluate the clinical response of PVV in the treatment of VD.

PATIENTS AND METHODS

Girls four years or older who consulted for PVV for at least one month and who did not respond to general measures. A physical examination was performed with visual inspection and colposcopy; vaginal samples for culture and vaginoscopy were carried out. On every patient urodynamic studies were performed. Girls who were diagnosed with VD were treated. A pediatric gynecologist did the follow-up; a successful response was considered when inflammatory symptoms and vaginal discharge ceased.

RESULTS

Twenty patients were included, mean age 8.6 years (range: 4.6-14 years); 75% prepubertal symptoms lasted for 1.8 years; 19 (95%) had urodynamia, 10 (52.6%) had an overactive bladder, 8 (42.1%) external bladder sphincter dyssynergia, 1 (5.2%) hypotonic bladder, and 13 (65%) showed improvement.

CONCLUSION

VD is an important cause when considering the etiology of PVV.

Comparison of efficacy and safety of ciprofloxacin otic solution 0.2% versus polymyxin B-neomycin-hydrocortisone in the treatment of acute diffuse otitis externa*

OBJECTIVE

To compare the efficacy and safety of ciprofloxacin otic solution 0.2% to polymyxin B-neomycin-hydrocortisone (PNH) otic solution in the treatment of acute diffuse otitis externa in children, adolescents, and adults.

METHODS

This was a randomized, parallel-group, evaluator-blind, active-controlled, multicenter, noninferiority study. The primary efficacy endpoint was clinical cure of otitis symptoms at the test-of-cure (TOC) visit. Clinical cure at the end-of-treatment (EOT) visit and percentages of patients with clinical improvement and resolution and/or improvement of otalgia at EOT and TOC visits were secondary efficacy endpoints.

RESULTS

A total of 630 patients were randomized to ciprofloxacin twice daily (n = 318) or PNH 3 times daily (n = 312) for 7 days. Ciprofloxacin was shown to be noninferior to PNH. The percentage of patients with clinical cure at the TOC visit was 86.6% with ciprofloxacin and 81.1% with PNH; the treatment difference was 5.6% in favor of ciprofloxacin (95% CI: -0.9 to 12.1). At the EOT visit, clinical cure was achieved in 70.0% and 60.5% of patients, respectively, with a treatment difference in favor of ciprofloxacin (9.5%, 95 CI: 1.2 to 17.9). In all secondary efficacy variables, ciprofloxacin and PNH showed similar results, including pain duration and resolution. The clinical cure rate for patients with baseline cultures showing P. aeruginosa was 87.5% in the ciprofloxacin group and 78.6% in the PNH group, a treatment difference of 8.9% in favor of ciprofloxacin (95% CI: 0.6 to 17.3); for patients with baseline cultures showing S. aureus, the clinical cure rate was 72.7% for the ciprofloxacin group and 75.9% for the PNH group (treatment difference of 3.1% in favor of PNH, 95% CI: -21.1% to 27.4%). Most adverse events were mild and unrelated to study medication in both treatment groups. A limitation of this study is the assessment of signs and symptoms at baseline and after treatment, which does not provide data to evaluate the interim response.

CONCLUSIONS

Ciprofloxacin otic solution 0.2% was found to be noninferior to PNH. This efficacy, good tolerability, and ease of administration make ciprofloxacin otic solution 0.2% without a topical steroid an attractive option for the treatment of acute otitis externa.

Pediatric renal transplantation: a single center experience over 14 years

Between 1989 and 2003, 100 transplants were performed in 96 patients at the pediatric nephrology unit of the Calvo Mackenna Children's Hospital. Mean age 10.9 +/- 3.9 yr (1-17.6), 30% from LD. Donors were younger than 5 yr in five patients and all recipients received an 'en bloc' graft. Original disease was hypo/dysplasia 27%, reflux nephropathy 22 and 17% chronic glomerulonephritis. The immunosuppressive protocol during the first period (n = 56, 1989-2000): Cyclosporine, steroids and azathioprine, and during the second period (n = 44, 2001-2003): FK, steroids, MMF and anti-CD25 antibody (mAbs). AR was reported in 22 patients, 11% in LD, 31% in DD (p < 0.01). The AR rate decreased from 40 to 8% after anti-CD25 monoclonal induction. Patient actuarial survival rate at 1, 3 and 5 yr was 100% for LD and 96% for DD. The overall actuarial graft survival at 1,3, and 5 yr was 96.7, 96.7 and 71% for LD and 89, 76 and 73% for DD donors. Graft survival rate improved from the first period (1989-2000) to the second period (2001-2003; p = 0.05). No difference in graft survival rate with HLA-A,B,DR matching was found. Graft survival rate was better when cold ischemia time was <24 h (p < 0.01). CMV infections increased from 19 to 40% when MMF and anti-CD25 Ab were introduced (p < 0.01). The height/age Z score at 1, 3 and 5 yr post-transplant was -2.2, -2.1, -2.2, respectively, for children older than 7 yr and -1.8, -1.9, -2.1 for those transplanted younger than 7 yr of age who were switched to alternate day steroids (p < 0.01). The cause of graft lost was: chronic rejection eight, non-adherence four, AR four and vascular thrombosis two. The cause of death in two patients was fungus septicemia and accelerated rejection. Pediatric renal transplantation can be performed in our group with acceptable morbidity, low mortality and graft survival rates similar to other reports in North America and Western Europe. Graft survival rate improved with newer immunosuppression and greater experience at the center. Management of non-adherence and chronic rejection remain the major challenges.

Chordal cutting: a new therapeutic approach for ischemic mitral regurgitation

BACKGROUND

Mitral regurgitation (MR) conveys adverse prognosis in ischemic heart disease. Because such MR is related to increased leaflet tethering by displaced attachments to the papillary muscles (PMs), it is incompletely treated by annular reduction. We therefore addressed the hypothesis that such MR can be reduced by cutting a limited number of critically positioned chordae to the leaflet base that most restrict closure but are not required to prevent prolapse. This was tested in 8 mitral valves: a porcine in vitro pilot with PM displacement and 7 sheep with acute inferobasal infarcts studied in vivo with three-dimensional (3D) echo to quantify MR in relation to 3D valve geometry.

METHODS AND RESULTS

In all 8 valves, PM displacement restricted leaflet closure, with anterior leaflet angulation at the basal chord insertion, and mild-to-moderate MR. Cutting the 2 central basal chordae reversed this without prolapse. In vivo, MR increased from 0.8+/-0.2 to 7.1+/-0.5 mL/beat after infarction and then decreased to 0.9+/-0.1 mL/beat with chordal cutting (P<0.0001); this paralleled changes in the 3D leaflet area required to cover the orifice as dictated by chordal tethering (r(2)=0.76).

CONCLUSIONS

Cutting a minimum number of basal chordae can improve coaptation and reduce ischemic MR. Such an approach also suggests the potential for future minimally invasive implementation.

Paradoxic decrease in ischemic mitral regurgitation with papillary muscle dysfunction: insights from three-dimensional and contrast echocardiography with strain rate measurement

BACKGROUND

Ischemic mitral regurgitation (MR) was first ascribed to papillary muscle (PM) contractile dysfunction. Current theories include apical leaflet tethering caused by left ventricular (LV) distortion, but PM dysfunction is still postulated and commonly diagnosed. PM contraction, however, parallels apical tethering, suggesting the hypothesis that PM contractile dysfunction can actually diminish MR due to ischemic distortion of the inferior base alone.

METHODS AND RESULTS

We therefore occluded the proximal circumflex circulation in 7 sheep while maintaining PM perfusion, confirmed by contrast echocardiography. By 3D echocardiography, we measured the tethering distance between the ischemic medial PM tip and anterior annulus and LV ejection volume to give MR (by subtracting flowmeter LV outflow). In 6 sheep without initial MR, inferior ischemia alone produced PM tip retraction with restricted leaflet closure and mild-to-moderate MR (regurgitant fraction, 25.2+/-2.8%). Adding PM ischemia consistently decreased MR and tethering distance (5.2+/-0.3 to 1.4+/-0.3 mL; +3.8+/-0.5 mm to -2.2+/-0.7 mm axially relative to baseline; P<0.001) as PM strain rate decreased from +0.78+/-0.07 per second (contraction) to -0.42+/-0.06 per second (elongation, P<0.001) and leaflet tenting decreased. In one sheep, prolapse and MR resolved with inferior ischemia and recurred with PM ischemia.

CONCLUSIONS

PM contractile dysfunction can paradoxically decrease MR from inferobasal ischemia by reducing leaflet tethering to improve coaptation. This emphasizes the role of geometric factors in ischemic MR mechanism and potential therapy.

Cessation of platelet-mediated cyclic canine coronary occlusion after thrombolysis by combining nitric oxide inhalation with phosphodiesterase-5 inhibition

OBJECTIVES

We sought to evaluate the ability of type 5 phosphodiesterase (PDE5) inhibitors to augment the antithrombotic effects of inhaled nitric oxide (NO) in a canine model of platelet-mediated coronary thrombosis after thrombolysis.

BACKGROUND

Type 5 phosphodiesterase inhibitors potentiate the ability of NO to inhibit platelet aggregation in vitro by preventing platelet cyclic guanosine monophosphate catabolism. We previously reported that breathing low concentrations of NO gas attenuated, but did not prevent, cyclic flow reductions (CFRs) in a canine model of coronary thrombosis after thrombolysis.

METHODS

Cyclic flow reductions were induced after creation of a left anterior descending coronary artery stenosis, endothelial injury, thrombus formation and thrombolysis. Dogs were either untreated or treated with inhaled NO (20 ppm by volume), intravenous zaprinast, intravenous dipyridamole or the combination of inhaled NO with either PDE5 inhibitor (n = 4 per group).

RESULTS

Cyclic flow reductions ceased, and complete coronary patency was achieved in all dogs after they breathed NO combined with zaprinast (by 12.0+/-4.7 min [mean +/- SEM]) or dipyridamole (by 9.8+/-4.7 min). The frequency of CFRs was unaffected by NO, dipyridamole or zaprinast alone. Systemic arterial blood pressure and bleeding time were unchanged with any treatment. Ex vivo thrombin-induced platelet aggregation in dogs breathing NO and receiving dipyridamole was reduced by 75+/-7% (p < 0.05).

CONCLUSIONS

The PDE5 inhibitors potentiated the antithrombotic properties of inhaled NO in a canine model of platelet-mediated coronary artery thrombosis after thrombolysis, without prolonging the bleeding time or causing systemic hypotension.

Mechanism of ischemic mitral regurgitation with segmental left ventricular dysfunction: three-dimensional echocardiographic studies in models of acute and chronic progressive regurgitation

OBJECTIVES

This study aimed to separate proposed mechanisms for segmental ischemic mitral regurgitation (MR), including left ventricular (LV) dysfunction versus geometric distortion by LV dilation, using models of acute and chronic segmental ischemic LV dysfunction evaluated by three-dimensional (3D) echocardiography.

BACKGROUND

Dysfunction and dilation-both mechanisms with practical therapeutic implications-are difficult to separate in patients.

METHODS

In seven dogs with acute left circumflex (LCX) coronary ligation, LV expansion was initially restricted and then permitted to occur. In seven sheep with LCX branch ligation, LV expansion was also initially limited but became prominent with remodeling over eight weeks. Three-dimensional echo reconstruction quantified mitral apparatus geometry and MR volume.

RESULTS

In the acute model, despite LV dysfunction with ejection fraction = 23 +/- 8%, MR was initially trace with limited LV dilation, but it became moderate with subsequent prominent dilation. In the chronic model, MR was also initially trace, but it became moderate over eight weeks as the LV dilated and changed shape. In both models, the only independent predictor of MR volume was increased tethering distance from the papillary muscles (PMs) to the anterior annulus, especially medial and posterior shift of the ischemic medial PM, measured by 3D reconstruction (r2 = 0.75 and 0.86, respectively). Mitral regurgitation volume did not correlate with LV ejection fraction or dP/dt.

CONCLUSIONS

Segmental ischemic LV contractile dysfunction without dilation, even in the PM territory, fails to produce important MR. The development of MR relates strongly to changes in the 3D geometry of the mitral apparatus, with implications for approaches to restore a more favorable configuration.

The power-velocity integral at the vena contracta: A new method for direct quantification of regurgitant volume flow

BACKGROUND

Noninvasive quantification of regurgitation is limited because Doppler measures velocity, not flow. Because backscattered Doppler power is proportional to sonified blood volume, power times velocity should be proportional to flow rate. Early studies, however, suggested that this held only for laminar flow, not for regurgitant jets, in which turbulence and fluid entrainment augment scatter. We therefore hypothesized that this Doppler power principle can be applied at the proximal vena contracta, where flow is laminar before entrainment, so that the power-times-velocity integral should vary linearly with flow rate and its time integral with stroke volume (SV).

METHODS AND RESULTS

This was tested in vitro with steady and pulsatile flow through 0.07- to 0.8-cm(2) orifices and in 36 hemodynamic stages in vivo, replacing the left atrium with a rigid chamber and column for direct visual recording of mitral regurgitant SV (MRSV). In 12 patients, MRSV was compared with MRI mitral inflow minus aortic outflow and in 11 patients with 3D echo left ventricular ejection volume-Doppler aortic forward SV. Vena contracta power in the narrow high-velocity spectrum from a broad measuring beam was calibrated against that from a narrow reference beam of known area. Calculated and actual flow rates and SV correlated well in vitro (r=0.99, 0.99; error=-1.6+/-2.5 mL/s, -2. 4+/-2.9 mL), in vivo (MRSV: r=0.98, error=0.04+/-0.87 mL), and in patients (MRSV: r=0.98, error=-2.8+/-4.5 mL).

CONCLUSIONS

The power-velocity integral at the vena contracta provides an accurate direct measurement of regurgitant flow, overcoming the limitations of existing Doppler techniques.

Design of a new surgical approach for ventricular remodeling to relieve ischemic mitral regurgitation: insights from 3-dimensional echocardiography

BACKGROUND

Mechanistic insights from 3D echocardiography (echo) can guide therapy. In particular, ischemic mitral regurgitation (MR) is difficult to repair, often persisting despite annular reduction. We hypothesized that (1) in a chronic infarct model of progressive MR, regurgitation parallels 3D changes in the geometry of mitral leaflet attachments, causing increased leaflet tethering and restricting closure; therefore, (2) MR can be reduced by restoring tethering geometry toward normal, using a new ventricular remodeling approach based on 3D echo findings.

METHODS AND RESULTS

We studied 10 sheep by 3D echo just after circumflex marginal ligation and 8 weeks later. MR, at first absent, became moderate as the left ventricle (LV) dilated and the papillary muscles shifted posteriorly and mediolaterally, increasing the leaflet tethering distance from papillary muscle tips to the anterior mitral annulus (P<0.0001). To counteract these shifts, the LV was remodeled by plication of the infarct region to reduce myocardial bulging, without muscle excision or cardiopulmonary bypass. Immediately and up to 2 months after plication, MR was reduced to trace-to-mild as tethering distance was decreased (P<0.0001). LV ejection fraction, global LV end-systolic volume, and mitral annular area were relatively unchanged. By multiple regression, the only independent predictor of MR was tethering distance (r(2)=0.81).

CONCLUSIONS

Ischemic MR in this model relates strongly to changes in 3D mitral leaflet attachment geometry. These insights from quantitative 3D echo allowed us to design an effective LV remodeling approach to reduce MR by relieving tethering.

Myocardial perfusion and wall motion in infarction border zone: assessment by myocardial contrast echocardiography

Several mechanisms have been proposed to explain the decreased wall motion (WM) at the borders of myocardial infarction (MI). We used myocardial contrast echocardiography (MCE) to investigate the relation of perfusion to WM in infarcted border zones (BZs) 6 weeks after MI in 5 sheep. After quantifying the extent of WM abnormality and the perfusion defect, normal (NL), infarcted, and BZs were defined. Peak intensity after contrast was measured in acoustic units (AU). Radiolabeled microspheres were injected to measure regional blood flow. The heart was stained with 2,3, 5-triphenyltetrazolium chloride (TTC). The perfusion defect on MCE was 33% +/- 7% of the total myocardial area and correlated well with TTC (r = 0.92, P <.03). The BZ was 8% +/- 5% of the total myocardial area. Peak intensity after contrast was decreased in MI compared with BZ and NL (MI: 2.5 +/- 1.9 AU, BZ: 8.0 +/- 3.8 AU, P <.005; NL: 10.2 +/- 6.9 AU, P <.02) and comparable in NL and BZ. The blood flow measured by microspheres was not different in NL and BZ but was decreased in MI (NL: 1.6 mL/g/min, BZ: 1.5 +/- 0.5 mL/g/min, MI: 0.7 +/- 0.5 mL/g/min; P <.0001). In this model of chronic ovine MI, the BZ was small and its perfusion was preserved. These findings support the hypothesis that tethering of normal myocardial segments explains the abnormal wall motion noted at the borders of MI.

Emergency department visits associated with traumatic brain injury: United States, 1995-1996

The purposes of this study were to provide a national estimate of the incidence of traumatic brain injuries (TBIs) seen in emergency departments (EDs), but not requiring hospitalization and to determine the causes of these injuries. Using the Centers for Disease Control and Prevention case definition of TBI, ED data was analysed from the National Hospital Ambulatory Medical Care Survey (1995-1996). The average overall incidence rate of TBI-related ED visits for persons who were not hospitalized was 392/100,000 population per year, or 1,027,000 visits to hospital EDs in the US each year. This estimate is nearly twice (392 vs. 216) the previously estimated incidence rate, which was based on data from the 1991 National Health Interview Survey Injury Supplement. It was found that the highest incidence rate occurred among children aged 0-14 years, the rate for males was higher than for females, and the primary reported causes of these injuries were 'falls', motor vehicle-related causes, and 'struck by an object'. Although often considered 'mild' TBIs, these injuries can lead to significant cognitive and emotional impairment. Thus, continued surveillance of TBI-related ED visits is an important part of a comprehensive TBI prevention strategy.

Adenoviral gene transfer of SERCA2a improves left-ventricular function in aortic-banded rats in transition to heart failure

In human and experimental models of heart failure, sarcoplasmic reticulum Ca(2+) ATPase (SERCA2a) activity is decreased, resulting in abnormal calcium handling. The disturbances in calcium metabolism have been shown to contribute significantly to the contractile dysfunction observed in heart failure. We investigated whether increasing SERCA2a expression can improve ventricular function in an animal model of heart failure obtained by creating ascending aortic constriction in rats. After 19-23 wk of banding during the transition from compensated hypertrophy to heart failure (documented by >25% decrease in fractional shortening), rats were randomized to receive either an adenovirus carrying the SERCA2a gene (Ad.SERCA2a, n = 13) or beta-galactosidase (Ad.betagal, n = 14) by using a catheter-based technique. The failing hearts infected with Ad. betagal were characterized by a significant decrease in SERCA2a expression and a decrease in SERCA2a activity compared with nonfailing sham-operated rats (n = 11). In addition, these failing hearts had reduced left-ventricular systolic pressure, maximal rate of left-ventricular pressure rise and decline (+dP/dt, -dP/dt), and rate of isovolumic relaxation (tau). Overexpression of SERCA2a restored both SERCA2a expression and ATPase activity to nonfailing levels. Furthermore, rats infected with Ad.SERCA2a had significant improvement in left-ventricular systolic pressure, +dP/dt, -dP/dt, and rate of isovolumic relaxation (tau) normalizing them back to levels comparable to sham-operated rats. In this study, we show that in an animal model of heart failure where SERCA2a protein levels and activity are decreased and severe contractile dysfunction is present, overexpression of SERCA2a in vivo restores both systolic and diastolic function to normal levels.

Surveillance for injuries and violence among older adults

PROBLEM/CONDITION

Injuries and violence are major causes of disability and death among adults aged > or =65 years in the United States. Injuries impair older adults' quality of life and result in billions of dollars in health-care expenditures each year.

REPORTING PERIOD

This report reviews 1987-1996 data regarding fall-related deaths, 1988-1996 data on hospitalizations for hip fracture, 1990-1997 data regarding motor vehicle-related injuries, 1990-1996 data on suicides, and 1987-1996 data on homicides.

DESCRIPTION OF SYSTEMS

Data on fall-related deaths, suicides, and homicides are from the National Center for Health Statistics annual mortality data tapes for 1987-1996. Homicide data are supplemented with information from the Federal Bureau of Investigation's Supplemental Homicide Reports for 1987-1996. Data on hospitalizations for hip fracture are from the 1988-1996 National Hospital Discharge Surveys. Information regarding motor vehicle-related injuries for 1990-1997 is from the National Highway Traffic Safety Administration's Fatality Analysis Reporting System and General Estimates System.

RESULTS

Rates of fall-related deaths for older adults increased sharply with advancing age and were consistently higher among men in all age categories. Men were 22% more likely than women to sustain fatal falls. A trend of increasing rates of fall-related deaths was observed from 1987 through 1996 in the United States, although rates were consistently lower for women throughout this period. Rates of hospitalizations for hip fracture differed by age and were higher for white women than for other groups. Rates increased with advancing age for both sexes but were consistently higher for women in all age categories. U.S. hospitalization rates for hip fracture increased for women from 1988 through 1996 while the rates for men remained stable. Rates of motor vehicle-related injuries increased slightly from 1990 through 1997, and marked variations in state-specific death rates were observed; in most states, older men had death rates approximately twice those for older women. Although suicide rates remain higher among older adults than among any other age group, rates of suicide among adults aged > or =65 years decreased 16% during the study period. Suicide rates among older adults varied by sex and age group. Homicide rates declined 36% among older adults. Homicide rates were highest for black men, followed by black women and white men; the homicide risk for blacks relative to whites decreased from 4.8 to 3.9 per 100,000 persons, indicating that the gap between rates for blacks and whites is closing. Half of the older homicide victims were killed by someone they knew.

INTERPRETATION

The increase in rates of fall-related deaths and hip fracture hospitalizations from 1988 through 1996 might reflect a change in the proportion of adults aged > or =85 years compared with those aged 65-84 years - a change that results, in part, from reduced mortality from cardiovascular and other chronic diseases. Fall-related death rates might be higher among older men because they often have a higher prevalence of comorbid conditions than women of similar age. Racial differences in hospitalization rates might have some underlying biologic basis; the prevalence of osteoporosis, a condition that contributes to reduced bone mass and increased bone fragility, is greatest among older white women. Compared with whites aged > or =65 years, blacks of comparable ages have greater bone mass and are less likely to sustain fall-related hip fractures. Additional studies are needed to determine why rates of motor vehicle-related injury have increased slightly among older adults and why these rates vary by state. Declining rates of suicide among older adults might be related to changes in the effect or type of risk factors traditionally observed in this age group. Research is needed to identify reasons for variations in suicide rates among older persons. Homicides among olde

Epidemiological approach to quality assessment in echocardiographic diagnosis

OBJECTIVES

This study sought to determine whether statistical analysis of a computerized clinical diagnostic database can be used as a tool for quality assessment by determining the contribution of reader bias to variance in diagnostic output.

BACKGROUND

In industry, measurement of product uniformity is a key component of quality assessment. In echocardiography, quality assessment has focused on review of small numbers of cases, or prospective determination of reader variability in selected and relatively small subsets. However, diagnostic biases in clinical practice might be discerned utilizing large computerized databases to determine interreader differences in diagnostic prevalence and, with use of appropriate statistical methods, to determine the association of reader selection with diagnostic prevalence independently of other covariates.

METHODS

We analyzed 6,026 echocardiograms in a computerized database, read by one of three level 3 (American Society of Echocardiography) readers, for differences in frequency among four coded echocardiographic diagnoses: mitral valve prolapse, valvular vegetations, left ventricular (LV) thrombus, and LV regional wall-motion abnormality.

RESULTS

Significant differences (up to fourfold) were found between readers, which persisted after statistical adjustment for those population characteristics, which differed slightly between readers. The low population prevalence of these conditions would have made it unlikely that these interreader differences could be detected by nonstatistical methods. Additionally, chamber dimensions differed between readers and were not normally distributed.

CONCLUSIONS

Statistically based quality assessment analysis of computerized clinical databases facilitates ongoing monitoring of interreader bias despite low diagnostic prevalence, and targets opportunities for subsequent quality improvement.

Regulation of cardiac hypertrophy in vivo by the stress-activated protein kinases/c-Jun NH(2)-terminal kinases

Cardiac hypertrophy often presages the development of heart failure. Numerous cytosolic signaling pathways have been implicated in the hypertrophic response in cardiomyocytes in culture, but their roles in the hypertrophic response to physiologically relevant stimuli in vivo is unclear. We previously reported that adenovirus-mediated gene transfer of SEK-1(KR), a dominant inhibitory mutant of the immediate upstream activator of the stress-activated protein kinases (SAPKs), abrogates the hypertrophic response of neonatal rat cardiomyocytes to endothelin-1 in culture. We now report that gene transfer of SEK-1(KR) to the adult rat heart blocks SAPK activation by pressure overload, demonstrating that the activity of cytosolic signaling pathways can be inhibited by gene transfer of loss-of-function mutants in vivo. Furthermore, gene transfer of SEK-1(KR) inhibited pressure overload-induced cardiac hypertrophy, as determined by echocardiography and several postmortem measures including left ventricular (LV) wall thickness, the ratio of LV weight to body weight, cardiomyocyte diameter, and inhibition of atrial natriuretic factor expression. Our data suggest that the SAPKs are critical regulators of cardiac hypertrophy in vivo, and therefore may serve as novel drug targets in the treatment of hypertrophy and heart failure.

[Adequacy of continuous ambulatory peritoneal dialysis in children]

When the use of dialytical therapy is decided after a careful assessment of clinical and laboratory variables, the close supervision of the procedure, that allows a feedback between our indications and its clinical efficacy, is essential. The correct and routine use of validated adequacy tools such as Kt/V and the Peritoneal Equilibration Test (PET) is mandatory. We compare the adequacy figures for adult and pediatric populations, mentioning the Kt/V and PET values obtained in eight patients followed during 12 months in a Nephrology Unit. An initial Kt/V of 2.04 and of 2.14 after 12 months of procedure are values that adjust to the general recommendations discussed in this paper. According to PET results, this group of patients were classified as low average for ultrafiltration and high average for creatinine clearance. Based on the local experience and literature review, some recommendations are made for the management of peritoneal dialysis in children.

The prevalence of disability from chronic conditions due to injury among adults ages 18-69 years: United States, 1994

PURPOSE

To describe the causes and determine the prevalence of disability from chronic conditions due to injury among US civilian non-institutionalized persons aged 18-69 years.

METHODS

Data from the National Health Interview Survey Disability (NHIS-D) Supplement Phase I, United States 1994 were analysed and six disability categories were examined: activities of daily living (ADL), instrumental activities of daily living (IADL), functional activities (FA), sight, hearing, and communication.

RESULTS

In 1994, 5.6 million persons aged 18-69 years reported a disability because of a chronic condition that was caused by injury. The prevalence of ADL disability due to chronic conditions caused by injury was 370 per 100000 population; IADL disability was 1256; FA disability was 2512; sight was 231; hearing was 339; and communication was 91 per 100000 population. Fifty per cent of ADL, IADL, and FA disabilities were attributed to motor vehicle crashes and falls, as were 31% of sight, 19% of hearing, and 23% of communication disabilities.

CONCLUSIONS

Though these estimates may be conservative, this study indicates that injury is a major cause of disability in addition to a leading cause of death in the US.

Myocardial perfusion and right ventricular function

OBJECTIVE

Maximal right ventricular (RV) performance is influenced by left heart hemodynamics and hence coronary perfusion. We examined the role of myocardial perfusion of the right ventricle as potential determinant of maximal RV function.

MATERIALS AND METHODS

In 6 canine isovolumic right heart preparations, incremental volumes were introduced into a high compliance RV balloon until RV failure occurred. Maximal RV developed pressure (RVDP) and maximal positive RV dP/dt were determined at a constant controlled left ventricular (LV) output of 2 l/min and at controlled mean arterial pressures of 50, 80 and 120 mmHg. Right coronary artery (RCA) flow was measured.

RESULTS

Maximal RVDP increased significantly with increasing mean arterial pressures (44.8+/-11.2 vs 57.2+/-15.5 vs 75.4+/-2.5 mmHg for systemic pressures of 50, 80 and 120 mmHg respectively, p < 0. 05). With increasing mean arterial pressures RCA flow increased significantly (33.1+/-11.0 vs 46.1+/-20.4 vs 79.6+/-35.3 ml/min). At the onset of RV failure, RCA blood flow significantly decreased in all preparations compared to the maximal flow in the RCA (1.9+/-1.0 vs 33.1+/-11.0 ml/min at 50 mmHg; 13.6+/-10.2 vs 46.1+/-20.4 ml at 80 mmHg and 18.7+/-8.0 vs 79.6+/-35.3 ml/min at 120 mmHg; p < 0.05).

CONCLUSIONS

These results suggest that coronary perfusion is a major determinant of maximal RV function. The coronary artery driving pressure must be sufficient to avoid the onset of RV failure. Maintaining systemic pressure and hence RV myocardial blood flow may thus extend RV function.

Abnormal global left ventricular relaxation occurs early during the development of pharmacologically induced ischemia

In animal and human models, left ventricular (LV) diastolic function has been observed to be highly sensitive to myocardial ischemia. The response of LV diastolic parameters to pharmacologically induced ischemia, however, has not been characterized and might be important in the interpretation of dobutamine stress echocardiography. Eight mongrel dogs, in which were inserted a high-fidelity micromanometer LV catheter, coronary sinus sampling catheter, and ultrasonic coronary artery flow probe, underwent intravenous dobutamine infusion at escalating doses both before (control protocol) and after (ischemia protocol) creation of left anterior descending coronary artery stenosis with a hydraulic cuff occluder adjusted to maintain resting coronary artery flow but attenuate reactive hyperemia. At each dobutamine dose, epicardial short-axis 2-dimensional echocardiographic images and hemodynamic measurements were obtained. LV diastolic function was examined by calculation of peak (-)dP/dt and the time constant of isovolumic relaxation (tau). The dobutamine infusion protocol was terminated on the earliest recognition of an anterior wall motion abnormality. Peak (+)dP/dt normalized for developed isovolumetric pressure was calculated as a relatively load-independent index of global LV contractile function. Dobutamine infusion with and without ischemia resulted in comparable changes in heart rate and (+)dP/dt/IP, with no change in LV end-diastolic or -systolic pressure. The magnitude of peak (-)dP/dt increased less during the ischemia (1231 +/- 109 to 1791 +/- 200 mm Hg/sec) versus the control (1390 +/- 154 to 2432 +/- 320 mm Hg/sec) protocol (P <.05). Similarly, the observed decrease in tau was less during the ischemia (53 +/- 3 to 38 +/- 4 msec) than the control (51 +/- 5 to 23 +/- 3 msec) protocol, corresponding to a slower rate of relaxation (P <.05). In addition, the smaller decrease in tau was observed at the dobutamine dose before the dose at which an echocardiographic wall motion abnormality was first recognized. Dobutamine-induced ischemia is associated with abnormal LV diastolic function. In addition, these abnormalities seem to occur early in the development of ischemia. These observations extend to pharmacologically induced ischemia prior findings from other models of ischemia, suggesting the high sensitivity of LV diastolic function to the development of myocardial ischemia.

Contribution of the interventricular septum to maximal right ventricular function

OBJECTIVE

Maximal right ventricular (RV) function is influenced by left heart hemodynamics, possibly mediated by the interventricular scpturn (IVS). We examined the potential contribution of the IVS function to right heart function.

METHODS

In 12 canine isovolumic right heart preparations, incremental volumes were introduced into a high compliance RV balloon until RV failure occurred. Maximal RV developed pressure (RVDP) and maximal positive RV dP/dt were determined with a working IVS at a constant left ventricular (LV) output of 2 l/min and at a constant mean arterial pressure of 80 mmHg. Thereafter the IVS was thermally inactivated, and measurements were repeated using the same protocol.

RESULTS

At constant arterial pressure and constant LV output, thermal inactivation of the IVS led to a significant decrease in maximal RVDP (inactivated vs. working IVS: 36.1+/-9.8 vs. 56.8+/-16.2 mmHg, respectively, P < 0.001), and RV dP/dt (inactivated vs. working IVS: 720+/-220 vs. 1350+/-190 mmHg/s, respectively, P < 0.001).

CONCLUSIONS

These results suggest that the functional status of the IVS is a major determinant of maximal RV function. At constant LV conditions and arterial pressure, an inactivated IVS leads to a significant decrease in maximal RVDP and RV dP/dt under the conditions of this study.

Modulation of ventricular function through gene transfer in vivo

We used a catheter-based technique to achieve generalized cardiac gene transfer in vivo and to alter cardiac function by overexpressing phospholamban (PL) which regulates the activity of the sarcoplasmic reticulum Ca2+ ATPase (SERCA2a). By using this approach, rat hearts were transduced in vivo with 5 x 10(9) pfu of recombinant adenoviral vectors carrying cDNA for either PL, beta-galactosidase (beta-gal), or modified green fluorescent protein (EGFP). Western blot analysis of ventricles obtained from rats transduced by Ad.PL showed a 2.8-fold increase in PL compared with hearts transduced by Ad.betagal. Two days after infection, rat hearts transduced with Ad.PL had lower peak left ventricular pressure (58.3 +/- 12.9 mmHg, n = 8) compared with uninfected hearts (92.5 +/- 3.5 mmHg, n = 6) or hearts infected with Ad.betagal (92.6 +/- 5.9 mmHg, n = 6). Both peak rate of pressure rise and pressure fall (+3, 210 +/- 298 mmHg/s, -2, 117 +/- 178 mmHg/s, n = 8) were decreased in hearts overexpressing PL compared with uninfected hearts (+5, 225 +/- 136 mmHg/s, -3, 805 +/- 97 mmHg/s, n = 6) or hearts infected with Ad.betagal (+5, 108 +/- 167 mmHg/s, -3, 765 +/- 121 mmHg/s, n = 6). The time constant of left ventricular relaxation increased significantly in hearts overexpressing PL (33.4 +/- 3.2 ms, n = 8) compared with uninfected hearts (18.5 +/- 1.0 ms, n = 6) or hearts infected with Ad.betagal (20.8 +/- 2.1 ms, n = 6). These differences in ventricular function were maintained 7 days after infection. These studies open the prospect of using somatic gene transfer to modulate overall cardiac function in vivo for either experimental or therapeutic applications.

Insights from three-dimensional echocardiography into the mechanism of functional mitral regurgitation: direct in vivo demonstration of altered leaflet tethering geometry

BACKGROUND

Recent advances in three-dimensional (3D) echocardiography allow us to address uniquely 3D scientific questions, such as the mechanism of functional mitral regurgitation (MR) in patients with left ventricular (LV) dysfunction and its relation to the 3D geometry of mitral leaflet attachments. Competing hypotheses include global LV dysfunction with inadequate leaflet closing force versus geometric distortion of the mitral apparatus by LV dilatation, which increases leaflet tethering and restricts closure. Because geometric changes generally accompany dysfunction, these possibilities have been difficult to separate.

METHODS AND RESULTS

We created a model of global LV dysfunction by esmolol and phenylephrine infusion in six dogs. initially with LV expansion limited by increasing pericardial restraint and then with the pericardium opened. The mid-systolic 3D relations of the papillary muscle (PM) tips and mitral valve were reconstructed. Despite severe LV dysfunction (ejection fraction, 18+/-6%), only trace MR developed when pericardial restraint limited LV dilatation; with the pericardium opened, moderate MR accompanied LV dilatation (end-systolic volume, 44+/-5 mL versus 12+/-5 mL control, P<.001). Mitral regurgitant volume and orifice area did not correlate with LV ejection fraction and dP/dt (global function) but did correlate with changes in the tethering distance from the PMs to the anterior annulus derived from the 3D reconstructions, especially PM shifts in the posterior and mediolateral directions, as well as with annular area (P<.0005). By multiple regression, only changes in the PM-to-annulus distance independently predicted MR volume and orifice area (R2=.82 to .85, P=2x10(-7) to 6x10(-8)).

CONCLUSIONS

LV dysfunction without dilatation fails to produce important MR. Functional MR relates strongly to changes in the 3D geometry of the mitral valve attachments at the PM and annular levels, with practical implications for approaches that would restore a more favorable configuration.

A new, biventricular working heterotopic heart transplant model: anatomic and physiologic considerations

BACKGROUND

Current heterotopic heart transplant models have nonworking left ventricles that atrophy and are not suitable for some studies. We developed and characterized a new heterotopic model with working left and right ventricles.

METHODS

Hemodynamics were compared in the working and nonworking models. The influence of the length of the donor's aorta on coronary arterial oxygenation was tested. The influence of the recipient's arterial pressure on developed left ventricular systolic pressure and the effects of alpha- and beta-adrenergic stimulation were examined in both models. The nonworking and working models were compared in chronic transplant preparations to investigate possible ventricular atrophy.

RESULTS

In this model, coronary arterial oxygen tension was influenced by the length of the donor's aorta. With a short donor aorta (0.5 cm in the porcine model), normal coronary arterial oxygenation is maintained. Left ventricular systolic pressure was greater in the working compared with the nonworking models. Left ventricular systolic pressure did not respond to alpha-adrenergic stimulation but did respond to beta-adrenergic and combined stimulation, which indicates its relationship to donor heart output. Left ventricular systolic pressure correlated with and was determined by recipient arterial pressure. Ventricular atrophy occurred in the nonworking model, but ventricular weight was maintained at sham control levels in this new working model.

CONCLUSION

These results demonstrate the surgical anatomic considerations of a new heterotopic heart transplant model in which the left and right ventricles work. Its hemodynamic performance is related to recipient hemodynamics, and the model responds to adrenergic stimulation. In chronic studies, ventricular mass is maintained, thus allowing this model to overcome a significant shortcoming of existing heterotopic heart transplant models.

Percutaneous transvenous intracardiac ultrasound imaging in dogs: a new approach to monitor left ventricular function

OBJECTIVE

To evaluate the feasibility and ability of percutaneous transvenous intracardiac echocardiography (ICE) to image the left ventricle (LV) and monitor its function from the right ventricular (RV) cavity.

METHODS

A 10 MHz catheter was advanced into the RV from the jugular vein and positioned along the septum at the LV papillary muscle level in five dogs. The catheter was manipulated until a stable catheter position along the septum, which provided on-axis images of LV, was obtained. Different states of LV size and systolic function (n = 80) were created with dobutamine or esmolol, both in the presence and absence of coronary stenoses. LV stroke area (cm2) obtained by ICE was measured at the mid-ventricular level and compared with stroke volume (cm3) obtained simultaneously with a transaortic flow probe. LV end diastolic, end systolic, and stroke areas obtained by ICE were also compared with those obtained by short-axis epicardial echocardiography.

RESULTS

In 96% of the stages, short axis images of the LV could be obtained and measured by ICE. LV end diastolic, end systolic, and stroke areas measured by ICE were not significantly different from epicardial echocardiographic values. Stroke area correlated with stroke volume in each dog (mean correlation coefficient 0.79 (SEE 0.19) cm2) (P < 0.001).

CONCLUSIONS

Percutaneous intracardiac ultrasound imaging allows monitoring of LV function from the RV with an accuracy comparable to a short-axis epicardial echocardiogram. The present device can be used in closed chest experimental studies. With the development of lower frequency devices, this technique may be valuable for continuous monitoring of LV function in patients in the intensive care unit or operating room.

Inhaled nitric oxide increases coronary artery patency after thrombolysis

BACKGROUND

Nitric oxide (NO) and nitrosovasodilators that release NO inhibit platelet aggregation. The antithrombotic effect of intravenously infused nitrosovasodilators is usually accompanied by systemic vasodilation. Inhaled NO is a pulmonary vasodilator that does not produce systemic hemodynamic effects. This study examines the antithrombotic effect of inhaled NO in a canine model of platelet-mediated coronary artery reocclusion after thrombolysis.

METHODS AND RESULTS

In 25 anesthetized dogs, a segment of the left anterior descending coronary artery was traumatized and a high-grade stenosis created. Thrombus was injected at this site, and tissue plasminogen activator was administered, producing cyclic flow variations (CFVs) in 24 of 25 dogs. CFV frequency was unchanged in dogs not breathing NO but decreased by 35 +/- 9% (P < .05) and 53 +/- 7% (P < .01) while dogs breathed 20 and 80 parts per million (ppm) NO, respectively. The coronary artery patency ratio (fraction of time during which the coronary artery was patent; CAPR) was unchanged in dogs not treated with NO but increased from 51 +/- 7% to 64 +/- 8% while breathing 20 ppm NO (P < .01) and from 49 +/- 3% to 75 +/- 7% while breathing 80 ppm NO (P < .01). The increased CAPR during 80 ppm NO administration persisted during a 45-minute posttreatment period (70 +/- 7%, P < .05 versus baseline). NO inhalation did not change systemic hemodynamics. In a pharmacological model of coronary vasoconstriction, inhaled NO did not reverse the effect of the thromboxane A2 agonist U-46619. In vitro ADP-induced platelet aggregation was inhibited by NO gas.

CONCLUSIONS

Inhaled NO at concentrations of 20 and 80 ppm increases coronary patency and decreases CFV frequency in a canine model of platelet-mediated coronary reocclusion after thrombolysis without producing systemic hemodynamic effects.

Do not resuscitate orders and pediatric patients: the role of a clinical ethics committee in a developing country

No published information is currently available about formal "do not resuscitate" (DNR) orders for pediatric patients in developing countries, even though there has been extensive discussion of how to determine who should be involved. This article reports the experience of a clinical ethics committee that recommended DNR orders at a pediatric public hospital in Chile. The committee consisted of four permanent physician members and temporary members including clergymen, nurses, the head of the patient's hospital unit, and the attending physician. Attending physicians submitted cases to the committee on a voluntary basis, and the committee's recommendations were not binding. During the 1990-1993 study period the committee recommended issuing DNR orders for 16 of the 34 patients it evaluated. The hospital records of these 16 patients were retrospectively reviewed for information about the patient's age and diagnosis, the committee's specific recommendations, and the outcome of the case. It was found that the committee typically recommended specific measures to help the child's parents and attending staff in addition to the DNR order. The average patient age was 2 years and 2 months. Nearly all of the patients had chronic and multiple pathologies. In all cases the committee recommendations (taken by consensus) were followed by the attending physician with the consent of the patient's parents. Eleven of the 16 patients for whom DNR orders were issued died during the study period. The five others remained alive despite respiratory insufficiency, severe neurologic damage, or hepatic failure. In general the committee's recommendations appeared useful, providing stronger arguments for DNR decisions and suggesting further support measures for patients, their families, and the attending professionals. This finding supports the idea that clinical ethics committees can provide both valuable support and an opportunity to arrive at better decisions in the public hospitals of developing countries.

Effect of beta-blockade on dobutamine stress echocardiography

Dobutamine is an effective pharmacologic stress used in conjunction with echocardiography because of its beta-agonist properties. Concurrent beta-blockade might alter this effectiveness; however, current clinical experience has been variable. The purpose of this study is to determine whether concurrent beta-blockade alters the ability of a dobutamine stress echocardiogram to detect a fixed coronary stenosis by preventing the onset of a wall motion abnormality or by altering the dose at which the wall motion abnormality appears. Paired dobutamine stress tests with and without beta-blockade (esmolol 500 microgram/kg initial bolus, 100 microg/kg/min infusion) were performed in a canine model (n = 8) with a fixed single-vessel coronary stenosis. Heart rate, systolic pressure, proximal left anterior descending coronary flow, myocardial thickening (by sonomicrometry), and left ventricular area change (by epicardial echocardiography) were monitored. Simultaneous beta-blockade resulted in (1) a delayed and diminished increase in hemodynamic parameters (peak heart rate 164.1 +/- 22.3 without beta-blockade vs 110.1 +/- 28.9 beats/min with beta-blockade, p < 0.001, and peak systolic blood pressure 137.9 +/- 26.8 mm Hg without beta-blockade vs 107.3 +/- 15.3 mm Hg with beta-blockade, p = 0.01), (2) an elimination of the physiologic effects of low-dose (5 and 10 microg/kg/min) dobutamine (-0.7 percent +/- 16.7 percent change in myocardial thickening from baseline with beta-blockade, p = NS), and (3) an elimination or alteration in timing of inducible wall motion abnormalities caused by severe coronary artery stenoses (mean termination dose 28.8 +/- 9.9 with beta-blockade vs 15.6 +/- 6.1 microg/kg/min without beta-blocker, p < 0.01). The findings in this canine model suggest that the competitive antagonist markedly attenuates the ability of dobutamine stress echocardiography to detect a significant coronary lesion and may alter its ability to detect viable myocardium at low-dose testing. Further clinical studies to determine the sensitivity of dobutamine stress echocardiography in the presence of beta-blockers and to establish protocol standards are necessary.

Intracardiac echocardiography: in vitro and in vivo validation for right ventricular volume and function

To determine the feasibility and accuracy of intracardiac ultrasonography (ICUS) for the measurement of right ventricular (RV) volumes and function, a 10 MHz ICUS catheter was used in an in vitro and in vivo model. In the in vitro study, 16 sheep hearts were imaged. Sequential cross-sectional images from RV apex to base were recorded during a calibrated pullback. Volumes were calculated by applying Simpson's algorithm. ICUS-obtained volumes correlated well with actual volumes (standard error of estimate [SEE] = 2.3 ml, r = 0.98). For the in vivo study, a beating-heart canine model was used (31 hemodynamic stages in six dogs). Actual volumes were measured by an intracavitary balloon connected to an external column. Sequential cross-sectional images were recorded during the ICUS catheter pullback from apex to base of the RV, and volumes calculated by Simpson's algorithm. Good correlations were observed between ICUS and actual values for diastolic (SEE = 4.1 ml, r = 0.97), systolic (SEE = 3.4 ml, r = 0.96), and ejection fraction (SEE = 3.1%, r = 0.87) values. This new technique can accurately quantitate RV volumes, can function both in vitro and in vivo, and has the potential for increasing applications to questions of clinical and research interest.

New method for accurate calculation of regurgitant flow rate based on analysis of Doppler color flow maps of the proximal flow field. Validation in a canine model of mitral regurgitation with initial application in patients

OBJECTIVES

The purpose of this study was to develop a rational and objective method for selecting a region in the proximal flow field where the hemispheric formula for calculating regurgitant flow rates by the flow convergence technique is most accurate.

BACKGROUND

A major obstacle to clinical implementation of the proximal flow convergence method is that it assumes hemispheric isovelocity contours throughout the Doppler color flow map, whereas contour shape depends critically on location in the flow field.

METHODS

Twenty mitral regurgitant flow rate stages were produced in six dogs by implanting grommet orifices into the anterior mitral leaflet and varying driving pressures so that actual peak flow rate could be determined from the known effective regurgitant orifice times the orifice velocity. Because plotting flow rate calculated by using a hemispheric formula versus alias velocities produces underestimation near the orifice and overestimation far from it, this plot was fitted to a polynomial function to allow identification of an inflection point within a relatively flat intermediate zone, where factors causing overestimation and underestimation are expected to be unimportant or balanced. The accuracy of flow rate calculation by the inflection point was compared with unselective and selective averaging techniques. Clinical relevance, initial feasibility and correlation with an independent measure were tested in 13 consecutive patients with mitral regurgitation who underwent cardiac catheterization.

RESULTS

1) The accuracy of single-point calculations was improved by selecting points in the flat portion of the curve (y = 1.15x - 3.34, r = 0.87, SEE = 22.1 ml/s vs. y = 1.34x - 1.99, r = 0.71, SEE = 45.6 ml/s, p < 0.01). 2) Selective averaging of points in the flat portion of the curve further improved accuracy and decreased scatter compared with unselective averaging (y = 1.08x + 4.8, r = 0.96, SEE = 11.6 ml/s vs. y = 1.30x + 0.6, r = 0.90, SEE = 20.9 ml/s, p < 0.01). 3) The proposed algorithm for mathematically identifying the inflection point provided the best results (y = 0.96x + 4.5, r = 0.96, SEE = 9.9 ml/s), with a mean error of 1.6 +/- 9.7 ml/s vs. 11.4 +/- 11.7 ml/s for selective averaging (p < 0.01). In patients, the proposed algorithm identified an inflection point at which calculated regurgitant volume agreed best with invasive measurements (y = 1.1x - 0.61, r = 0.93, SEE = 17 ml).

CONCLUSIONS

The accuracy of the proximal flow convergence method can be significantly improved by analyzing the flow field mathematically to identify the optimal isovelocity zone before using the hemispheric formula to calculate regurgitant flow rates. Because the proposed algorithm is objective, operator independent and, thus, suitable for automatization, it could provide the clinician with a powerful quantitative tool to assess valvular regurgitation.

Effect of beta-adrenergic receptor blockade on the physiologic response to dobutamine stress echocardiography

Dobutamine is an effective pharmacologic stress agent because of its beta-adrenergic receptor agonist properties. Theoretically, concurrent beta-adrenergic receptor blockade might alter this effectiveness, but clinical experience has been variable. Before assessing the relative effectiveness and implications of dobutamine stress echocardiography (DSE) to detect myocardial ischemia in the presence of beta-blockade the physiologic and hemodynamic effects of dobutamine with simultaneous beta-blockade must be understood in a controlled setting. Therefore the purpose of this study was to determine if beta-blocking agents alter the timing and magnitude of the physiologic response to graded doses of dobutamine during a standard DSE. Paired DSEs were performed in seven instrumented open-chest dogs with and without beta-blockade (esmolol 500 micrograms/kg initial bolus and 100 micrograms/kg/min infusion). Heart rate, systolic pressure, proximal left anterior descending coronary artery flow, myocardial thickening, and percentage left ventricular area change (% AC) were monitored. The data for each parameter were fit to linear or exponential functions. With graded doses of dobutamine, the rate of increase in coronary flow was greater than that in %AC, which in turn was greater than that in heart rate (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Intracardiac ultrasonographic assessment of atrial septal defect area: in vitro validation and technical considerations

Assessment of atrial septal defect (ASD) size and shape is important for planning and guiding its transcatheter occlusion and can potentially be achieved by intracardiac ultrasonography (ICUS). ICUS accuracy, however, must first be established against stable standards and technical imaging requirements defined. We therefore used 10, 20, and 30 MHz ICUS catheters to examine 17 ASDs that were 0.16 to 6.7 cm2 in area and were surgically created in excised ovine hearts with 10, 20, and 30 MHz ICUS catheters. ASD shape and area by ICUS were compared with direct video images of the actual ASD. In all instances minimal area by ICUS pullback agreed well with actual values (y = 1.04x + 0.2, SEE = 0.23 cm2, r = 0.99) and corresponded well with defect shapes. The maximum angle between ultrasonography beam and septal plane allowing for complete ASD visualization was 20 degrees. The angle depended on transducer frequency and septal thickness. This new technique has potential value for the accurate assessment of ASD shape and size and may be especially useful in the setting of transcatheter occlusion.

Pulsatile pressure affects the disappearance of echocardiographic contrast agents

The purpose of this study was to determine in an in vitro model the effect of pulsatile pressure on the decay of echocardiographic contrast agents. Use of contrast agents for quantitative assessment of perfusion requires understanding of the factors controlling their rates of disappearance. Prior studies have shown that constant pressure affects the rate of disappearance of these agents. It is not known whether pulsatile pressure influences the rate of decay of contrast agents. In an in vitro chamber, three contrast agents (Albunex, hand-agitated saline solution, and hand-agitated Angiovist) were exposed to pulses of pressure at three rates (30, 60, and 120 pulsations/min), keeping pressure characteristics (peak, nadir, and mean) within a narrow range. Five injections were performed for each agent at each rate. Two-dimensional echocardiographic images of the effects of contrast material were recorded from injection until total disappearance. Videointensity was measured and time-intensity curves were generated. These curves of intensity decay were fitted to an exponential decay function (I = Ae-lambda t) and the velocity of decay (lambda) was used for comparisons. For all agents, intensity of contrast decreased over time. Saline solution and Angiovist, but not Albunex, showed pulsatile decreases in intensity of contrast with each peak pressure and partial recovery of contrast intensity with each nadir pressure. (ABSTRACT TRUNCATED AT 250 WORDS)

Experimental ablation of outflow tract muscle with a thermal balloon catheter

BACKGROUND

Pulmonary balloon valvuloplasty has been performed in selected patients with tetralogy of Fallot as an alternative to surgical palliation; this technique is limited, however, by the fact that the balloon has little effect on the dynamic, muscular contribution to outflow tract obstruction. In an experimental model, we used a new thermal balloon catheter to ablate right ventricular outflow tract muscle. We evaluated the acute efficacy and muscle ablation parameters of this technology and its effects after myocardial healing.

METHODS AND RESULTS

A prototype electrolyte-filled balloon catheter, heated by radiofrequency energy, was constructed. Studies were conducted to determine the optimum electrolyte solution needed to minimize balloon heating time with an unmodified, commercially available radiofrequency generator. In vivo ablations of right ventricular outflow tract muscle with the thermal balloon were performed in lambs that were divided into three groups (n = 5 each) according to the duration of thermal energy delivery (20, 40, and 60 seconds, respectively). Ablated lesion volume increased (460 +/- 63 to 1156 +/- 256 mm3) as the energy delivery time increased (20 to 60 seconds) and was correlated with delivered energy, temperature integral, and maximum epicardial surface temperature (r = .85, .82, and .72, respectively). All five lesions in the 60-second group showed an acute decrease of the wall thickness. Additional in vivo ablations were performed in 6 animals in which survival studies showed muscle thinning, healing by fibrosis, and no evidence of aneurysm formation.

CONCLUSIONS

Thermal energy can be used with a balloon catheter delivery system to ablate myocardium. This study suggests that this energy delivery technology might be useful for relief of muscular outflow tract obstruction and that further studies are warranted.