Resuscitation fluids

BACKGROUND AND OBJECTIVES

The aim of this review was to summarize the properties of the commonly available resuscitation fluids and highlight where knowledge of the characteristics of individual fluids might guide their use in clinical practice. Some of the current controversies surrounding resuscitation fluids are also discussed. Blood or blood products, or strategies of fluid administration, are not focused upon.

CONCLUSIONS

The clinical trial data does not support the concept of a therapeutic advantage for either crystalloids or colloids, despite claimed theoretical advantages for both classes of fluid. The available colloid solutions have quite distinct profiles of activity, both in terms of their plasma volume expansion profile and other physiological and pharmacological properties. Recent data suggests that physiologically balanced crystalloid and colloid solutions may improve clinical outcomes when compared with saline-based fluids.

The relationship between obesity and mortality in patients with heart failure

OBJECTIVES

The study aimed to evaluate the role of obesity in the prognosis of patients with heart failure (HF).

BACKGROUND

Previous reports link obesity to the development of HF. However, the impact of obesity in patients with established HF has not been studied.

METHODS

We analyzed 1,203 patients with advanced HF followed in a comprehensive HF management program. The patients were subclassified into categories of body mass index (BMI) defined as: underweight BMI <20.7 (n = 164), recommended BMI 20.7 to 27.7 (n = 692), overweight BMI 27.8 to 31 (n = 168) and obese BMI >31 (n = 179). This sample size allows the detection of small effects (0.02), with a power of 0.80 and an alpha level of 0.05 for comparing one-year survival between BMI groups.

RESULTS

The four BMI groups had similar profiles in terms of ejection fraction (mean 0.22), sodium, creatinine and smoking. The obese and overweight groups had significantly higher rates of hypertension and diabetes, as well as higher levels of cholesterol, triglycerides and low density lipoprotein cholesterol. The four BMI groups had similar survival rates. Ejection fraction, HF etiology and angiotensin-converting enzyme inhibitor use predicted survival on univariate analysis (p < 0.01), although BMI did not. On multivariate analysis, cardiopulmonary exercise tests, pulmonary capillary wedge pressure and serum sodium were strong predictors of survival (p < 0.05). Higher BMI was not a risk factor for increased mortality, but was associated with a trend toward improved survival.

CONCLUSIONS

In a large cohort of patients with advanced HF of multiple etiologies, obesity is not associated with increased mortality and may confer a more favorable prognosis. Further studies need to delineate whether weight loss promotion in medically optimized patients with HF is a worthwhile therapeutic goal.

Inhaled nitric oxide for pulmonary hypertension after heart transplantation

BACKGROUND

Recipient pulmonary hypertension due to chronic congestive heart failure is a major cause of right ventricular (RV) dysfunction after heart transplantation. We hypothesized that inhaled nitric oxide (NO), in the postoperative period, would a) selectively reduce pulmonary vascular resistance and improve RV hemodynamics and b) reduce the incidence of RV dysfunction compared with a matched historical group.

METHODS

Sixteen consecutive adult heart transplant recipients with lowest mean pulmonary artery (PA) pressures >25 mmHg were prospectively enrolled. Inhaled NO at 20 parts per million (ppm) was initiated before termination of cardiopulmonary bypass (CPB). At 6 and 12 hours after CPB, NO was stopped for 15 minutes and systemic and pulmonary hemodynamics were measured. RV dysfunction was defined as central venous pressure >15 mmHg and consistent echocardiographic findings. The incidence of RV dysfunction and 30-day survival in this group was compared with a historical cohort of 16 patients matched for pulmonary hypertension.

RESULTS

Discontinuation of NO for 15 minutes at 6 hours after transplantation resulted in a significant rise in mean PA pressure, pulmonary vascular resistance (PVR), and RV stroke work index. Systemic hemodynamics were not affected by NO therapy. One patient in the NO-treated group, compared with 6 patients in the historical cohort group, developed RV dysfunction (P< .05). The 30-day survival in the NO-treated group and the historical cohort group were 100% and 81%, respectively (P> .05).

CONCLUSION

In heart transplant recipients with pulmonary hypertension, inhaled NO in the postoperative period selectively reduces PVR and enhances RV stroke work. Furthermore, NO reduces the incidence of RV dysfunction in this group of patients when compared with a historical cohort matched for pulmonary hypertension. Inhaled NO is a useful adjunct to the postoperative treatment protocol of heart transplant patients with pulmonary hypertension.

A repeatable laboratory method for testing the efficacy of biocides against toilet bowl biofilms

AIMS

The purpose of this study was to develop a laboratory biofilm growth reactor system that simulated the toilet bowl environment and which could be used for biocide efficacy testing.

METHODS AND RESULTS

A microbial biofilm reactor system incorporating intermittent flow and nutrient provision was designed. The reactor system was open to the air and was inoculated with organisms collected from toilet bowl biofilms. Once per hour, reactors were supplied with a nutrient solution for a period of 5 min, then flushed and refilled with tap water or tap water amended with chlorine. Quantitative measures of the rate and extent of biofilm accumulation were defined. Biofilm accumulated in untreated reactors to cell densities of 108 cfu cm-2 after approximately 1 week. Biofilm accumulation was also observed in reactors in the continuous presence of several milligrams per litre of free chlorine. Repeatability standard deviations for the selected efficacy measures were low, indicating high repeatability between experiments. Log reduction values of viable cell numbers were within ranges observed with standard suspension and hard surface disinfection tests. Biofilm accumulated in laboratory reactors approximately seven times faster than it did in actual toilet bowls. The same ranking was achieved in tests between laboratory biofilms and field-grown biofilms with three of the four measures, using three different concentrations of chlorine.

CONCLUSION

This reactor system has been shown to simulate, in a repeatable way, the accumulation of bacterial biofilm that occurs in toilet bowls. The results demonstrate that this system can provide repeatable assays of the efficacy of chlorine against those biofilms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The laboratory biofilm reactor system described herein can be used to evaluate potential antimicrobial and antifouling treatments for control of biofilm formation in toilet bowls.

Educational needs of patients with advanced heart failure and their caregivers

At the time of initial transplant evaluation, we evaluated the information and counseling needs of 82 outpatients with advanced heart failure and compared them with the needs of 74 of their caregivers. Both groups answered a 23-item questionnaire, which used a 5-point Likert scale to assess needs across 6 sub-scales specific to heart failure and the process of determining transplant eligibility. The 5 most important learning needs of patients and caregivers were similar, and we found significant differences only in the groups' responses to 3 individual questions. We conclude that nurses can meet the needs of patients and their caregivers by providing honest explanations, focusing on enhanced quality of life issues, and giving information for dealing with an emergency.

Exaggerated muscle mechanoreflex control of reflex renal vasoconstriction in heart failure

In heart failure (HF) patients, reflex renal vasoconstriction during exercise is exaggerated. We hypothesized that muscle mechanoreceptor control of renal vasoconstriction is exaggerated in HF. Nineteen HF patients and nineteen controls were enrolled in two exercise protocols: 1) low-level rhythmic handgrip (mechanoreceptors and central command) and 2) involuntary biceps contractions (mechanoreceptors). Renal cortical blood flow was measured by positron emission tomography, and renal cortical vascular resistance (RCVR) was calculated. During rhythmic handgrip, peak RCVR was greater in HF patients compared with controls (37 +/- 1 vs. 27 +/- 1 units; P < 0.01). Change in (Delta) RCVR tended to be greater as well but did not reach statistical significance (10 +/- 1 vs. 7 +/- 0.9 units; P = 0.13). RCVR was returned to baseline at 2-3 min postexercise in controls but remained significantly elevated in HF patients. During involuntary muscle contractions, peak RCVR was greater in HF patients compared with controls (36 +/- 0.7 vs. 24 +/- 0.5 units; P < 0.0001). The Delta RCVR was also significantly greater in HF patients compared with controls (6 +/- 1 vs. 4 +/- 0.6 units; P = 0.05). The data suggest that reflex renal vasoconstriction is exaggerated in both magnitude and duration during dynamic exercise in HF patients. Given that the exaggerated response was elicited in both the presence and absence of central command, it is clear that intact muscle mechanoreceptor sensitivity contributes to this augmented reflex renal vasoconstriction.

Gastric tonometry: where do we stand?

Gastric tonometry has proved to be a sensitive but not specific predictor of outcome in the critically ill. The data accumulated to date indicate that those patients able to achieve or maintain a normal gastric mucosal pH do better than those who do not. In addition, therapy aimed at improving an abnormal gastric mucosal pH has proved to be less successful. These findings may simply indicate that tonometry identifies those "responders" and "nonresponders," as becomes increasingly apparent in populations of critical care patients receiving interventional therapy. Gastric tonometry has undergone a number of methodologic changes over the last decade, seeing a switch from saline to automated gas tonometry. Along with this switch of methodology has come a deeper scrutiny of the indices used to assess gut perfusion. Most studies (including all the interventional ones) have used gastric mucosal pH. The newer indices of gut luminal PCO2 (PgCO2) referenced to arterial CO2 (PgCO2-PaCO2) or end tidal CO2 (PgCO2-PeCO2), although relatively well validated, remain to be proven as predictors of outcome or guides to interventional therapy. If we take a fresh look at the interventional trials in intensive care patients, there is a very definite trend toward benefit in the protocol groups, although they are generally reported as negative studies. There is much to be accomplished, however, before we accept the gastric tonometer as a routine tool with which to guide therapy based on gastrointestinal perfusion, including a greater understanding of gastrointestinal physiology and, as ever, the call for an adequately powered prospective randomized controlled trial to evaluate the clinical utility of gas tonometry.

Freedom from congestion predicts good survival despite previous class IV symptoms of heart failure

BACKGROUND

This study determined whether evidence of congestion after 4 to 6 weeks of heart failure management predicted outcome for patients hospitalized with chronic New York Heart Association class IV symptoms. Class IV symptoms predict high mortality rates, but outcome is not known for patients who improve to establish freedom from congestion. Revised estimates at 1 month could facilitate decisions regarding transplantation and other high-risk interventions.

METHODS

At 4 to 6 weeks after hospital discharge, 146 patients were evaluated for congestion by 5 criteria (orthopnea, jugular venous distention, edema, weight gain, and new increase in baseline diuretics). Heart failure management included inpatient therapy tailored to relieve congestion, followed by adjustments to maintain fluid balance during the next 4 weeks.

RESULTS

Freedom from congestion was demonstrated at 4 to 6 weeks in 80 (54%) patients, who had 87% subsequent 2-year survival compared with 67% in 40 patients with 1 or 2 criteria of congestion and 41% in 26 patients with 3 to 5 criteria. The Cox proportional hazards model identified left ventricular dimension, pulmonary wedge pressure on therapy, and freedom from congestion as independent predictors of survival. Persistence of orthopnea itself predicted 38% 2-year survival (without urgent transplantation) versus 77% in 113 without orthopnea. Serum sodium was lower and blood urea nitrogen and heart rate higher when orthopnea persisted.

CONCLUSIONS

The ability to maintain freedom from congestion identifies a population with good survival despite previous class IV symptoms. At 4 to 6 weeks, patients with persistent congestion may be considered for high-risk intervention.

Metastatic paraganglioma causing spinal cord compression

We describe two cases of metastatic retroperitoneal paraganglioma associated with extradural spinal cord compression. Both occurred in young men; one being metastatic at presentation, the other becoming metastatic 19 years after attempted surgical resection. Despite a long, relatively stable natural history after diagnosis (10 and 19 years, respectively) both had an acceleration of their disease once extradural disease was detected. These cases illustrate the potentially aggressive nature of this disease, the need for long-term follow-up and the effectiveness of a variety of therapies for palliation, and also raise the possibility of "prophylactic" treatment to prevent spinal cord compression.

Apparent surface associated lag time in growth of primary biofilm cells

The ability of microorganisms to form biofilms has been well documented. Bacterial cells make a transition from a planktonic state to a sessile state, replicate, and subsequently populate a surface. In this study, organisms that initially colonize a ``clean'' surface are referred to as ``primary'' biofilm cells. The progeny of the first generation of sessile cells are known as ``secondary'' biofilm cells. This study examined the growth of planktonic, primary, and secondary biofilm cells of a green fluorescent protein producing (GFP+) Pseudomonas aeruginosa PA01. Biofilm experiments were performed in a parallel plate flow cell reactor with a glass substratum. Individual cells were tracked over time using a confocal scanning laser microscope (CSLM). Primary cells experience a lag in their growth that may be attributed to adapting to a sessile environment or undergoing a phenotypic change. This is referred to as a surface associated lag time. Planktonic and secondary biofilm cells both grew at a faster rate than the primary biofilm cells under the same nutrient conditions.

Integrated Paleomagnetism and U-Pb Geochronology of Mafic Dikes of the Eastern Anabar Shield Region, Siberia: Implications for Mesoproterozoic Paleolatitude of Siberia and Comparison with Laurentia

This article reports the first joint paleomagnetic and U-Pb geochronologic study of Precambrian diabase dikes in the Anabar Shield and adjacent Riphean cover of Siberia. It was undertaken to allow comparison with similar published studies in Laurentia and to test Proterozoic reconstructions of Siberia and Laurentia. An east-trending Kuonamka dike yielded a provisional U-Pb baddeleyite emplacement age of 1503+/-5 Ma and a virtual geomagnetic pole at 16 degrees S, 221 degrees E (dm=17&j0;, dp=10&j0;). A paleomagnetic pole at 6 degrees N, 234 degrees E (dm=28&j0;, dp=14&j0;) was obtained from five Kuonamka dikes. An east-southeast-trending Chieress dike yielded a U-Pb baddeleyite emplacement age of 1384+/-2 Ma and a virtual geomagnetic pole at 4 degrees N, 258 degrees E (dm=9&j0;, dp=5&j0;). Kuonamka and Chieress poles are interpreted to be primary but do not average out secular variation. Assuming that the Siberian Plate has remained intact since the Mesoproterozoic, except for mid-Paleozoic opening of the Viljuy Rift, then the above results indicate that the Siberian Plate was in low latitudes at ca. 1503 and 1384 Ma, broadly similar to low latitudes determined for Laurentia from well-dated paleopoles at 1460-1420, 1320-1290, and 1267 Ma. This would allow Laurentia and Siberia to have been attached in the Mesoproterozoic, as suggested in several recent studies based on geological criteria. However, because paleomagnetic results from the Anabar Shield region do not average out secular variation and the ages of poles from Siberia and Laurentia are not well matched, it is not yet possible to distinguish between these reconstructions or to rule out other configurations that also maintain the two cratons at low paleolatitudes.

Mechanical assist strategy using the BVS 5000i for patients with heart failure

BACKGROUND

The BVS 5000i external pulsatile assist device is used to support patients with reversible cardiogenic shock. Its low cost and potential for insertion without cardiopulmonary bypass make it an attractive option.

METHODS

Nineteen status I patients failing inotropic support were treated with the BVS 5000i with the intention of short-term bridge to transplant. Fourteen patients received left ventricular support whereas 5 received biventricular support. Cardiopulmonary bypass was used in less than 50% of patients.

RESULTS

Median support time was 7 days. The 2 myocarditis patients were weaned from support. Twelve patients were transplanted and there were 5 deaths on support. Overall 14 of 19 were transplanted or weaned. One-year survival was 79%. Median hospital stay was 31 days.

CONCLUSIONS

The BVS 5000i can be used for short-term mechanical assist toward transplantation in selected patients for whom a donor can be expected soon. The device may provide a cost-effective, short-term strategy to optimize end-organ function before orthotopic heart transplant, particularly for patients who are predictably not ideal to be discharged with implantable left ventricular assist device treatment.

Knee arthroscopy in the day surgery unit

General anaesthesia is usually the preferred technique, but spinal anaesthesia has many advantages in day-case surgery. It is easy to perform, has a rapid onset of action, blocks only the region being operated on, and provides good muscle relaxation and early postoperative analgesia. Spinal anaesthesia limits postanaesthetic nursing care, is less expensive and reduces the nausea and vomiting associated with general anaesthesia. However, day-case spinal anaesthesia remains controversial because of concerns over postdural puncture headache, backache and delayed micturition while prolonged motor blockade may preclude early mobilization and discharge.

Exaggerated renal vasoconstriction during exercise in heart failure patients

BACKGROUND

During static exercise in normal healthy humans, reflex renal cortical vasoconstriction occurs. Muscle metaboreceptors contribute importantly to this reflex renal vasoconstriction. In patients with heart failure, in whom renal vascular tone is already increased at rest, it is unknown whether there is further reflex renal vasoconstriction during exercise.

METHODS AND RESULTS

Thirty-nine heart failure patients (NYHA functional class III and IV) and 38 age-matched control subjects (controls) were studied. Renal blood flow was measured by dynamic positron emission tomography. Graded handgrip exercise and post-handgrip ischemic arrest were used to clarify the reflex mechanisms involved. During sustained handgrip (30% maximum voluntary contraction), peak renal vasoconstriction was significantly increased in heart failure patients compared with controls (70+/-13 versus 42+/-1 U, P=0.02). Renal vasoconstriction returned to baseline in normal humans by 2 to 5 minutes but remained significantly increased in heart failure patients at 2 to 5 minutes and had returned to baseline at 20 minutes. In contrast, during post-handgrip circulatory arrest, which isolates muscle metaboreceptors, peak renal vasoconstriction was not greater in heart failure patients than in normal controls. In fact, the increase in renal vasoconstriction was blunted in heart failure patients compared with controls (20+/-5 versus 30+/-2 U, P=0.05).

CONCLUSIONS

During sustained handgrip exercise in heart failure, both the magnitude and duration of reflex renal vasoconstriction are exaggerated in heart failure patients compared with normal healthy humans. The contribution of the muscle metaboreceptors to reflex renal vasoconstriction is blunted in heart failure patients compared with normal controls.

The life stages of weight: setting achievable goals appropriate to each woman

Weight is a preoccupation in America, especially among women. Using body mass index (BMI) as the measure, many women are found to be overweight (BMI 25-30 kg/m2) or obese (BMI >30 kg/m2). A BMI that is less than 18.5 kg/m2 reflects underweight, which is best considered separately. This paper is concerned with the classification of body weight, the distribution of body fat, and the nutritional, medical, and stage-of-life factors that affect fat deposition and weight. The main stages of life in regard to adiposity are the prenatal period, infancy and the period of adiposity rebound (childhood), adolescence, and finally adulthood, with some special considerations at and after menopause.

Impaired endothelium-mediated vasodilation is not the principal cause of vasoconstriction in heart failure

The extent to which abnormal endothelium-dependent vasodilator mechanisms contribute to abnormal resting vasoconstriction and blunted reflex vasodilation seen in heart failure is unknown. The purpose of this study was to test the hypothesis that the resting and reflex abnormalities in vascular tone that characterize heart failure are mediated by abnormal endothelium-mediated mechanisms. Thirteen advanced heart-failure patients (New York Heart Association III-IV) and 13 age-matched normal controls were studied. Saline, acetylcholine (20 microg/min), or L-arginine (10 mg/min) was infused into the brachial artery, and forearm blood flow was measured by venous plethysmography at rest and during mental stress. At rest, acetylcholine decreased forearm vascular resistance in normal subjects, but this response was blunted in heart failure. During mental stress with intra-arterial acetylcholine or L-arginine, the decrease in forearm vascular resistance was not greater than during saline control in heart failure [saline control vs. acetylcholine (7 +/- 3 vs. 6 +/- 3, P = NS) or vs. L-arginine (9 +/- 2 units, P = NS)]. The increase in forearm blood flow was not greater than during saline control in heart failure [saline control vs. acetylcholine (1. 2 +/- 0.3 vs. 1.3 +/- 0.3, P = NS), or vs. L-arginine (1.2 +/- 0.2 ml x min(-1) x 100 ml(-1), P = NS)]. Furthermore, during mental stress with nitroprusside, the decrease in forearm vascular resistance was not greater than during saline control [saline control vs. nitroprusside (7 +/- 3 vs. 5 +/- 4 ml x min(-1) x 100 g(-1), P = NS)], and the increase in forearm blood flow was not greater than during saline control [saline control vs. nitroprusside (1.2 +/- 0.3 vs. 1.3 +/- 0.5 ml x min(-1) x 100 g(-1), P = NS)]. Because the endothelial-independent agent nitroprusside was unable to restore resting and reflex vasodilation to normal in heart failure, we conclude that impaired endothelium-mediated vasodilation with acetylholine-nitric oxide cannot be the principal cause of the attenuated resting- or reflex-mediated vasodilation in heart failure.

Orogenesis and Basin Development: U-Pb Detrital Zircon Age Constraints on Evolution of the Late Paleozoic St. Marys Basin, Central Mainland Nova Scotia

The St. Marys Basin, along the southern flank of the composite Late Paleozoic Magdalen Basin in the Canadian Appalachians and along the Avalon-Meguma terrane boundary, contains Late Devonian-Early Carboniferous continental clastic rocks of the Horton Group that were deposited in fluvial and lacustrine environments after the peak of the Acadian orogeny. SHRIMP II (Geological Survey of Canada) data on approximately 100 detrital zircons from three samples of Horton Group rocks from the St. Marys Basin show that most of the zircons have been involved in a multistage history, recycled from clastic rocks in the adjacent Meguma and Avalonian terranes. Although there is a minor contribution from Early Silurian (411 Ma) and Late Devonian suites (ca. 380-370 Ma), Neoproterozoic (ca. 700-550 Ma) and Paleoproterozoic (ca. 2.0-2.2 Ga) zircon populations predominate, with a minor contribution from ca. 1.0-, 1.2-, and 1.8-Ga zircons. Published U-Pb single-zircon analyses on clastic sedimentary rocks indicate that the Meguma and Avalon terranes have different populations of detrital zircons, sourced from discrete portions (Amazonian and West African cratons) of the ancient Gondwanan margin. Both terranes contain Neoproterozoic and Late Archean populations. The SHRIMP data, in conjunction with published sedimentological and geochemical data, indicate that the Horton Group basin-fill sediments are largely the result of rapid uplift and erosion of Meguma terrane metasedimentary and granitoid rocks immediately to the south of the St. Marys Basin during the waning stages of the Acadian orogeny. Regional syntheses indicate that this uplift occurred before and during deposition and was a consequence of dextral ramping of the Meguma terrane over the Avalon terrane along the southern flank of the Magdalen Basin.

Relationship between right and left-sided filling pressures in 1000 patients with advanced heart failure

BACKGROUND

Elevated left ventricular filling pressures present a major target of therapy for symptomatic heart failure but are difficult to assess directly. Because the relationship of left- and right-sided pressures remains ill defined in chronic heart failure, this study compared 3 right-sided measurements (right atrial [RA] pressure, pulmonary artery systolic [PAS] pressure, and severity of tricuspid regurgitation [TR]) to the pulmonary capillary wedge (PCW) pressure.

METHODS

Hemodynamic measurements and echocardiography were available from 1000 patients undergoing transplant evaluation. Right atrial and PAS pressure, and TR severity were compared to PCW pressure. For 754 patients undergoing repeat measurements, changes in RA and PAS pressures were compared to PCW changes.

RESULTS

Right atrial pressure correlated with PCW pressure (r = 0.64), regardless of etiology or TR severity. Right atrial pressure changes correlated with PCW changes (r = 0.62). Discordance was defined as either RA > or = 10 mm Hg despite PCW < 22 mm Hg (6%) or RA < 10 mm Hg despite PCW > or = 22 mm Hg (15%). For detection of PCW > or = 22 mm Hg, positive predictive values were 88% for RA > or = 10 mm Hg, 95% for PAS > or = 60 mm Hg, and 79% for > or = moderate TR. Pulmonary artery systolic pressure correlated very closely with PCW (r = 0.79), and could be estimated as 2 x PCW. Reduction in PAS pressure during therapy was strongly determined by PCW pressure reduction (r = 0.67).

CONCLUSIONS

Accurate estimation of RA pressure can potentially guide therapy of left ventricular filling pressures in approximately 80% of chronic heart failure patients without obvious non-cardiac disease. In this population, elevated PAS pressures are largely determined by elevated left-sided filling pressures.

The 6-min walk and peak oxygen consumption in advanced heart failure: aerobic capacity and survival

BACKGROUND

This study sought to determine to what extent the 6-min walk (6MW) distance in advanced heart failure predicts aerobic capacity and provides comparable information regarding survival. Peak oxygen uptake ( VO(2)) and the 6MW both describe function and predict outcome over a wide range of heart failure, but their determinants and implications may differ within a narrower clinical spectrum. This study compared 6MW with aerobic capacity both at peak exercise and during low-level cycling.

METHODS AND RESULTS

Both the 6MW and symptom-limited cycle ergometry were performed by 307 patients of whom 264 patients additionally performed 6 min of 20-W cycling to estimate aerobic capacity during sustained low-level activity. In the first 198 patients, multivariate analysis of survival was performed with the 6MW and peak VO (2). Patients achieved the 6MW of 393 +/- 104 m and peak VO (2) of 14 +/- 5 mL/kg per minute. Although low peak VO (2) was more likely with the shorter 6MW, the relation was weak within peak VO (2) range of 10 to 20 mL/kg per minute (n = 213, 69% of patients, r = 0.28). During 20-W exercise, VO (2) was 9.2 +/- 2.0 mL/kg per minute, with respiratory exchange ratio poorly correlated with the 6MW. In contrast to peak VO (2), the 6MW in meters did not predict survival. Division into short, medium, and long walks, however, supplemented simple clinical description.

CONCLUSIONS

Although helpful in broader populations for identification of patients with obvious clinical compromise, the 6MW distance is not a surrogate for peak VO (2) in assessing aerobic capacity or prognosis for individuals with advanced heart failure.

The University of California at Los Angeles experience in heart transplantation

In the last decade, the number of patients undergoing heart transplant has steadily increased as a result of expanding indications for this procedure. The limitation on the number of transplants performed has been the number of donor organs available. At UCLA, 900 heart transplant procedures have been performed from 1984-1998. Since 1991, the percent of patients free from rejection and infection in the first year after transplant was 70% and 73%, respectively. Actuarial one-, 3-, and 5-year survival rates are 84%, 76%, and 72%, respectively. Survival of patients aged 60 years and over (n = 105) was comparable to that of patients under age 60. We have been pursuing corticosteroid-free immunosuppression, which has led to a decrease in infection complications. Our work with pravastatin early after transplantation has led to a decrease in clinically severe rejection episodes, which has translated into improved survival. Pravastatin also appears to decrease the development of transplant coronary artery disease and appears to have an adjunct immunosuppressive effect in our heart transplant patients on CsA-based immunosuppression. We have also demonstrated benefit of cardiac rehabilitation early after transplant which should therefore be considered as standard postoperative care. Finally, we have participated and led the multicenter mycophenolate study in demonstrating this drug's effectiveness in improved outcomes in primary heart transplant recipients. Future studies include the use of Rapamycin and interleukin-2 receptor blockers which have been demonstrated in kidney transplantation to significantly reduce rejection. Our program is committed to seek better ways to improve outcome and the quality of life of our heart transplant patients.

Repeatability and reproducibility of germicide tests: a literature review

The results of a quantitative antimicrobial assay can be summarized by the log reduction value. For an assay to be proposed as a standard method, it is usually necessary to conduct a collaborative study to demonstrate that the repeatability and reproducibility standard deviations (SDs) of the log reduction values are sufficiently small. It is not clear, however, precisely how small those SDs should be. This paper describes the results of a literature review conducted to determine the range of repeatability and reproducibility SDs for standard quantitative antimicrobial assays. The underlying premise is that, for an assay to have been accepted as a standard method, its repeatability and reproducibility SDs must have been sufficiently small. This premise implies that the repeatability and reproducibility SDs of standard assays establish de facto guidelines for acceptability. The survey comprised papers where the SDs could be extracted directly or where they could be calculated from accessible data. Papers describing suspension tests as well as hard surface tests were included. For the standard antimicrobial assays reviewed, repeatability SDs ranged from 0.25 to 1.21 and the reproducibility SDs ranged from 0.31 to 1.54.

A controlled trial of exercise rehabilitation after heart transplantation

BACKGROUND

In patients who have received a cardiac transplant, the denervated donor heart responds abnormally to exercise and exercise tolerance is reduced. The role of physical exercise in the treatment of patients who have undergone cardiac transplantation has not been determined. We assessed the effects of training on the capacity for exercise early after cardiac transplantation.

METHODS

Twenty-seven patients who were discharged within two weeks after receiving a heart transplant were randomly assigned to participate in a six-month structured cardiac-rehabilitation program (exercise group, 14 patients) or to undergo unstructured therapy at home (control group, 13 patients). Each patient in the exercise group underwent an individualized program of muscular-strength and aerobic training under the guidance of a physical therapist, whereas control patients received no formal exercise training. Cardiopulmonary stress testing was performed at base line (within one month after heart transplantation) and six months later.

RESULTS

As compared with the control group, the exercise group had significantly greater increases in peak oxygen consumption (mean increase, 4.4 ml per kilogram of body weight per minute [49 percent] vs. 1.9 ml per kilogram per minute [18 percent]; P=0.01) and workload (mean increase, 35 W [59 percent] vs. 12 W [18 percent]; P=0.01) and a greater reduction in the ventilatory equivalent for carbon dioxide (mean decrease, 13 [20 percent] vs. 6 [11 percent]; P=0.02). The mean dose of prednisone, the number of patients taking antihypertensive medications, the average number of episodes of rejection and of infection during the study period, and weight gain did not differ significantly between the groups.

CONCLUSIONS

When initiated early after cardiac transplantation, exercise training increases the capacity for physical work.

Effects of Substratum Topography on Bacterial Adhesion

The effect of substratum topography on bacterial surface colonization was studied using a chemically homogeneous silicon coupon. "Grooves" 10 µm deep and 10, 20, 30, and 40 µm wide were etched on the coupon perpendicular to the direction of flow. Flow (Re = 5.5) of a bacterial suspension (10(8) cells/ml) was directed through a parallel plate flow chamber inverted on a confocal microscope. Images were collected in real time to obtain rate and endpoint colonization data for each of three strains of bacteria: Pseudomonas aeruginosa and motile and nonmotile Pseudomonas fluorescens. A higher velocity experiment (Re = 16.6) and an abiotic control using hydrophilic, negatively charged microspheres were also performed. Using a colloidal deposition expression, the initial rates of attachment were compared. P. aeruginosa attached at a higher rate than P. fluorescens mot+ which attached at a higher rate than P. fluorescens mot-. For all bacteria the rate was independent of groove size and was greatest on the downstream edges of the grooves. Only the motile organisms were found in the bottoms of the grooves. A higher fluid velocity resulted in an increase in the initial rate of attachment. In contrast, there was no adhesion of the beads. Attachment of the bacteria appears to be predominated by transport from the bulk phase to the substratum. Copyright 1998 Academic Press.

Color measurement as a means of quantifying surface biofouling

Laboratory reactors fitted with removable ceramic porcelain growth surfaces were inoculated with a consortium of biofilm forming environmental isolates. A Minolta colorimeter CR-200 (Minolta Camera Co., Ltd, Ramsey, NJ) was used in conjunction with a specially designed adapter to evaluate the reflective color of the porcelain disks as biofilm accumulated on them. Areal viable cell counts were monitored over a period of eleven days in two separate experiments and direct color measurements of the untreated, microbially fouled test surfaces were collected. This colorimetric assay was both non-destructive and immediate. A strong linear relationship between log cell density and log color change was observed. The Pearson product moment correlation coefficient for all 45 observations combined was r = 0.95. Separate regression lines for each experiment were not significantly different (P = 0.19). When adjusted for time, the (partial) correlation coefficient between log cell density and log color change was r = 0.87, which suggests that the relationship between the two measures can not be explained by their mutual dependence on time. Reflective color measurement provided a rapid, non-destructive and quantitative measure of biofllm accumulation.

Skin test anergy in advanced heart failure secondary to either ischemic or idiopathic dilated cardiomyopathy

Skin tests to recall antigens are performed as indicators of clinical outcomes in heart failure (HF). A diminution in the response to recall antigens, termed "anergy," is regarded as an indication of poorer clinical prognosis, although little analysis has been done to support that conclusion. Patients with advanced HF (n=222) in New York Heart Association classes III and IV, with complete datasets for all of the variables, were studied. The sample was 77% men, mean age 52+/-12 years, and left ventricular ejection fraction, 21+/-7. Patients with ischemic (n=113) and idiopathic (n=109) disease were analyzed separately. The relation of anergy to 1-year mortality and selected hemodynamic factors, blood chemistries, medications, and nutritional status markers was analyzed. Anergy was present in 45% (47% idiopathic and 42% ischemic) of patients. Anergy was related to 1-year mortality (univariate p=0.038) in patients with ischemic, but not idiopathic, HF. Anergic patients with ischemic HF had shorter survival times (p=0.035). Lower cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides were predictors (p <0.001) of mortality in idiopathic HF. In ischemic HF, lower cholesterol, LDL, and triglycerides were univariate predictors (p <0.001, p=0.004, and p=0.005, respectively) of skin test anergy, but not mortality. Thus, there were distinct differences in clinical correlates of skin test anergy in patients with idiopathic and ischemic HF. This study supports evaluation of anergy to skin tests as one of the markers of mortality in patients with ischemic HF.

Safety and hemodynamic effects of intravenous triiodothyronine in advanced congestive heart failure

Most patients with advanced congestive heart failure have altered thyroid hormone metabolism. A low triiodothyronine level is associated with impaired hemodynamics and is an independent predictor of poor survival. This study sought to evaluate safety and hemodynamic effects of short-term intravenous administration of triiodothyronine in patients with advanced heart failure. An intravenous bolus dose of triiodothyronine, with or without a 6- to 12-hour infusion (cumulative dose 0. 1 5 to 2.7 microg/kg), was administered to 23 patients with advanced heart failure (mean left ventricular ejection fraction 0.22 +/- 0.01). Cardiac rhythm and hemodynamic status were monitored for 12 hours, and basal metabolic rate by indirect calorimetry, echocardiographic parameters of systolic function and valvular regurgitation, thyroid hormone, and catecholamine levels were measured at baseline and at 4 to 6 hours. Triiodothyronine was well tolerated without episodes of ischemia or clinical arrhythmia. There was no significant change in heart rate or metabolic rate and there was minimal increase in core temperature. Cardiac output increased with a reduction in systemic vascular resistance in patients receiving the largest dose, consistent with a peripheral vasodilatory effect. Acute intravenous administration of triiodothyronine is well tolerated in patients with advanced heart failure, establishing the basis for further investigation into the safety and potential hemodynamic benefits of longer infusions, combined infusion with inotropic agents, oral triiodothyronine replacement therapy, and new triiodothyronine analogs.

Impact of acute mental stress on sympathetic nerve activity and regional blood flow in advanced heart failure: implications for 'triggering' adverse cardiac events

BACKGROUND

Evidence is accumulating that specific "triggers," such as intense psychological stress, may precipitate myocardial infarction and sudden death. Patients with advanced heart failure have increased resting sympathoexcitation, which has been directly related to increased mortality. The impact of triggers on sympathetic nerve activity and regional blood flow in heart failure has not been examined in patients with heart failure.

METHODS AND RESULTS

Twenty-seven patients with heart failure (NYHA functional class III or IV) and 26 age-matched normal control subjects were studied. Muscle sympathetic nerve activity, heart rate, mean arterial pressure, forearm blood flow, and renal blood flow were measured during mental stress testing with mental arithmetic and Stroop color word test. Patients with heart failure had elevated levels of resting muscle sympathetic nerve activity and heart rate. Mental stress significantly increased muscle sympathetic nerve activity and heart rate in both patients with heart failure and control subjects, although the magnitude of increases tended to be blunted in patients with heart failure. Nevertheless, absolute levels of sympathetic activity in patients with heart failure remained significantly higher than levels in control subjects during mental stress. The decrease in renal blood flow in patients with heart failure was similar to that of control subjects, despite greater resting renal vasoconstriction. The increase in forearm blood flow during mental stress testing in patients with heart failure was blunted compared with that of control subjects.

CONCLUSIONS

Patients with heart failure do not have augmented muscle sympathetic nerve activity responses to mental stress, despite elevated resting levels of sympathetic activity, but they do have markedly higher absolute levels of sympathetic nerve activity during mental stress as well as at rest.

Impact of a comprehensive heart failure management program on hospital readmission and functional status of patients with advanced heart failure

OBJECTIVES

To assess the impact of a comprehensive heart failure management program, functional status, hospital readmission rate and estimated hospital costs were determined and compared for the 6 months before and the 6 months after referral.

BACKGROUND

The course of advanced heart failure is characterized by progressive clinical deterioration reflected in frequent hospital admissions, which comprise the major financial cost.

METHODS

Over a 3-year period, 214 patients were accepted for heart transplantation and discharged after evaluation, which included adjustments in medical therapy and intensive patient education. Patients were in New York Heart Association functional class III or IV (94 and 120 patients, respectively), with a mean left ventricular ejection fraction of 0.21, peak oxygen consumption of 11 ml/kg per min and a total of 429 hospital admissions in the previous 6 months (average 2.0 per patient). Changes in the medical regimen included a 98% increase in angiotensin-converting enzyme inhibitor dose and a flexible diuretic regimen after 4.2-liter net diuresis, with counseling also regarding diet and progressive exercise.

RESULTS

During the 6 months after referral, there were only 63 hospital readmissions (85% reduction), with 0.29/patient (p < 0.0001). Functional status improved as assessed by functional class (p < 0.0001) and peak oxygen consumption (15.2 vs. 11.0 ml/kg per min, p < 0.001). The same results were seen after excluding the 35 patients without full 6-month follow-up (9 deaths, 14 urgent transplant procedures during hospital readmission, 12 elective transplant procedures from home); 34 hospital admissions occurred after referral, compared with 344 before referral. Even when adding in the initial hospital admission after referral for these 179 patients, there was a 35% decrease in total hospital admissions in the 6-month period. The estimated savings in hospital readmission costs after subtracting the initial hospital costs for management was $9,800 per patient.

CONCLUSIONS

Comprehensive heart failure management led to improved functional status and an 85% decrease in the hospital admission rate for transplant candidates discharged after evaluation. The potential to reduce both symptoms and costs suggests that referral to a heart failure program may be appropriate not only for potential heart transplantation, but also for medical management of persistent functional class III and IV heart failure.

Sustained hemodynamic efficacy of therapy tailored to reduce filling pressures in survivors with advanced heart failure

BACKGROUND

During therapy to relieve congestion in advanced heart failure, cardiac filling pressures can frequently be reduced to near-normal levels with improved cardiac output. It is not known whether the early hemodynamic improvement and drug response can be maintained long term.

METHODS AND RESULTS

After referral for cardiac transplantation with initially severe hemodynamic decompensation, 25 patients survived without transplantation to undergo hemodynamic reassessment after 8+/-6 months of treatment tailored to early hemodynamic response. Initial changes included net diuresis, increased ACE inhibitor doses, and frequent addition of nitrates. After 8 months of therapy, early reductions were sustained for pulmonary wedge pressure (24+/-9 to 15+/-5 mm Hg early; 12+/-6 mm Hg late) and systemic vascular resistance (1651+/-369 to 1207+/-281 dynes x s(-1) x cm(-5) early; 1003+/-193 dynes x s(-1) x cm(-5) late). Acute response to doses persisted at reevaluation. Sustained reduction in filling pressures was accompanied by a progressive increase in stroke volume (42+/-10 to 56+/-13 mL early; 79+/-20 mL late), improved functional class, and freedom from resting symptoms. Study design did not control for amiodarone, which was initiated for arrhythmias in 12 patients and associated with greater improvement in cardiac index (1.8 to 3.2 L min(-1) x m(-2) late on amiodarone versus 2.0 to 2.6 L x min(-1) x m(-2), P<.05).

CONCLUSIONS

During chronic therapy tailored to early hemodynamic response in advanced heart failure, acute vasodilator response persists, and near-normal filling pressures can be maintained in patients who survive without transplantation. Stroke volumes at low filling pressures increase further over time. Chronic hemodynamic improvement was accompanied by symptomatic improvement, but the contributions of the monitored hemodynamic approach, increased vasodilator doses, and comprehensive outpatient management have not yet been established.

Improving survival for patients with atrial fibrillation and advanced heart failure

OBJECTIVES

We attempted to determine whether changes in heart failure therapy since 1989 have altered the prognostic significance of atrial fibrillation.

BACKGROUND

Atrial fibrillation occurs in 15% to 30% of patients with heart failure. Despite the recognized potential for adverse effects, the impact of atrial fibrillation on prognosis is controversial.

METHODS

Two-year survival for 750 consecutive patients discharged from a single hospital after evaluation for heart transplantation from 1985 to 1989 (Group I, n = 359) and from 1990 to April 1993 (Group II, n = 391) was analyzed in relation to atrial fibrillation. In Group I, class I antiarrhythmic drugs and hydralazine vasodilator therapy were routinely allowed. In Group II, amiodarone and angiotensin-converting enzyme inhibitors were first-line antiarrhythmic and vasodilating drugs.

RESULTS

A history of atrial fibrillation was present in 20% of patients in Group I and 24% of those in Group II. Patients with atrial fibrillation in the two groups had similar clinical and hemodynamic profiles. Among patients with atrial fibrillation, those in Group II had a markedly better 2-year survival (0.66 vs. 0.39, p = 0.001) and sudden death-free survival (0.84 vs. 0.70, p = 0.01) than those in Group I. In each time period, survival was worse for patients with than without atrial fibrillation in Group I (0.39 vs. 0.55, p = 0.002) but not in Group II (0.66 vs. 0.75, p = 0.09).

CONCLUSIONS

The prognosis of patients with advanced heart failure and atrial fibrillation is improving. These findings support the practice of avoiding class I antiarrhythmic drugs in this group and may reflect recent beneficial changes in heart failure therapy.

Dynamics of muscle sympathetic nerve activity in advanced heart failure patients

Muscle sympathetic nerve activity (MSNA) is increased in patients with heart failure compared with healthy subjects. We applied spectral and correlation techniques to determine if qualitative as well as quantitative differences in MSNA differentiate heart failure patients from healthy subjects. We recorded MSNA, heart rate, and respiration in 11 heart failure patients and 10 healthy humans. Our results are as follows. 1) Statistically significant low-frequency modulation of MSNA at 0.029 +/- 0.002 Hz (mean +/- SE; range 0.026-0.038 Hz) was found in 10 of 11 heart failure patients but in only 2 of 10 healthy controls (differences between groups, P < 0.01; chi 2 test). 2) Heart rate and respiration also demonstrated significant low-frequency modulation in a similar range. 3) Spectral and correlation techniques revealed that low-frequency modulation of MSNA was highly correlated with low-frequency modulation of respiration in heart failure patients, but not in healthy subjects. In contrast, low-frequency modulation of MSNA did not correlate well with low-frequency modulation of heart rate. In summary, low-frequency modulation of respiration is coupled to low-frequency modulation of MSNA in heart failure patients, but not in normal subjects. We speculate that this low-frequency modulation of respiration may represent subclinical Cheyne-Stokes breathing, which has marked qualitative effects on MSNA in patients with heart failure.

Pretransplant panel reactive-antibody screens. Are they truly a marker for poor outcome after cardiac transplantation?

BACKGROUND

The effect of pretransplant sensitization on outcome after cardiac transplant has been controversial. Sensitization, defined as a positive panel-reactive antibody (PRA) screen in patients awaiting transplant, represents circulating antibodies to a random panel of donor lymphocytes (usually T lymphocytes). The significance of pretransplant circulating antibodies to B lymphocytes has not been reported, and many centers disregard its use.

METHODS AND RESULTS

We retrospectively reviewed the pretransplant PRA screens for 311 patients who underwent cardiac transplant at our institution. The PRA screen was performed by use of the lymphocytotoxic technique treated with dithiothreitol to remove IgM autoantibodies. Patients with PRA > or = 11% against T or B lymphocytes had significantly lower 3-year survival (T lymphocytes, 39%; B lymphocytes, 56%) than those patients with PRA = 0% and PRA = 1% to 10% (T lymphocytes, 76% and 78%; B lymphocytes, 78% and 74%, respectively) (P < .001). For this high-risk group, the rejection episode tended to occur earlier than in those patients with PRA = 0% and PRA = 1% to 10% (T lymphocytes, 2.3 versus 4.0 and 3.8 months; B lymphocytes, 2.1 versus 4.1 and 3.4 months, respectively), and there were more clinically severe rejections that required OKT3 therapy.

CONCLUSIONS

Cardiac transplant patients with pretransplant T- and/or B-lymphocyte PRA > or = 11% despite negative donor-specific crossmatch at the time of transplant appear to have earlier and more severe rejection with significantly lower survival after transplant surgery. Modification of immunosuppression in these high-risk patients may be warranted.

Thyroid hormone abnormalities in heart failure: possibilities for therapy

Though thyroid hormone abnormalities have been identified in many cardiac conditions, the role of thyroid hormones in congestive heart failure has not been well defined. In a population of patients with advanced heart failure, a reduction in triiodothyronine (T3) with an increase in reverse T3 was identified in many patients, with an abnormally low ratio of T3/reverse T3 being the strongest predictor of mortality. Normalization of thyroid indices appeared to be necessary for prolonged survival to occur. To address the concern of T3 administration possibility exacerbating a hypermetabolic state, basal metabolic rate was measured in a group of advanced heart failure patients and was found to be generally within the normal range. A preliminary safety study of short-term intravenous T3 administration (bolus +/- 6 h infusion, total dose 0.15-2.7 micrograms/kg) was then performed in 23 patients under hemodynamic and electrocardiographic monitoring. There were neither adverse events nor substantial hemodynamic changes, but some patients had an increase in cardiac output, consistent with a peripheral vasodilatory effect. With this foundation, further investigation into the possible role of T3 and its analogs in congestive heart failure therapy may be pursued.

Quantitative analysis of a presence/absence microbiological assay: the hard surface carrier test of disinfectant efficacy

The Hard Surface Carrier Test (HSCT) is a presence/absence assay for determining the extent to which chemical disinfectants kill bacteria. The disinfectants are marketed for cleaning surfaces in hospitals, restaurants, the home, etc. In the HSCT, a presence response (or equivalently, a positive carrier) is recorded if one or more bacteria survive among M bacteria attached to a glass carrier and exposed to the chemical disinfectant; otherwise, the response is absence. The presence or absence response is observed for each of many (usually 60) glass carriers and the disinfectant is considered effective if few (e.g., < or = 5%) of the carriers are positive. It would be more satisfactory to microbiologists if effectiveness were based on the fraction of bacteria that survive exposure; denote the expected survival fraction by phi. An equivalent parameter commonly used in antimicrobial research is the log-reduction, denoted by psi, where psi = -log10(phi). Although the number M of bacteria on each exposed carrier is not known, this paper shows it is possible to estimate psi. The suggested estimator is based on the assumption that M follows a gamma distribution. The gamma parameters are estimated using counts of bacteria on the HSCT nonexposed (control) carriers. This paper provides a formula for the standard error of the estimate, a computer simulation technique for calculating the lower confidence limit, and a computer simulation study of these statistical methods.

Improving survival for patients with advanced heart failure: a study of 737 consecutive patients

OBJECTIVES

This study sought to determine whether survival and risk of sudden death have improved for patients with advanced heart failure referred for consideration for heart transplantation as advances in medical therapy were systematically implemented over an 8-year period.

BACKGROUND

Recent survival trials in patients with mild to moderate heart failure and patients after a myocardial infarction have shown that angiotensin-converting enzyme inhibitors are beneficial, type I antiarrhythmic drugs can be detrimental, and amiodarone may be beneficial in some groups. The impact of advances in therapy may be enhanced or blunted when applied to severe heart failure.

METHODS

One-year mortality and sudden death were determined in relation to time, baseline variables and therapeutics for 737 consecutive patients referred for heart transplantation and discharged home on medical therapy from 1986 to 1988, 1989 to 1990 and 1991 to 1993. Medical care was directed by a single team of physicians with policies established by consensus. From 1986 to 1990, the hydralazine/isosorbide dinitrate combination or angiotensin-converting enzyme inhibitors were the initial vasodilators, and class I antiarrhythmic drugs were allowed. After 1990, captopril was the initial vasodilator, given to 86% of patients compared with 46% of patients before 1989. After mid-1989, class I agents were routinely withdrawn, and amiodarone was used for frequent ventricular ectopic beats or atrial fibrillation (53% of patients after 1990 vs. 10% before 1989).

RESULTS

The total 1-year mortality rate decreased from 33% before 1989 to 16% after 1990 (p = 0.0001), and sudden death decreased from 20% to 8% (p = 0.0006). Adjusted for clinical and hemodynamic variables in multivariate proportional hazards models, total mortality and sudden death were lower after 1990.

CONCLUSIONS

The large reduction in mortality, particularly in sudden death, from advanced heart failure since 1990 may reflect an enhanced impact of therapeutic advances shown in large randomized trials when they are incorporated into a comprehensive approach in this population. This improved survival supports the growing practice of maintaining potential heart transplant candidates on optimal medical therapy until clinical decompensation mandates transplantation.

Target heart failure populations for newer therapies

BACKGROUND

The scarcity of donor hearts has created a large population of heart failure patients who are unlikely to undergo transplantation. Newer surgical therapies that might sustain such patients at home previously have been applied in critical situations in which early outcome is jeopardized by multiorgan failure. The optimal population for studies of extended support would be ambulatory patients with low operative risk but high risk of later unfavorable outcome.

METHODS AND RESULTS

Baseline clinical, echocardiographic, and hemodynamic data were collected prospectively between 1988 and 1993 in 500 patients who were discharged on tailored medical therapy after evaluation for transplantation. Specific criteria were examined to identify high risk of death or need for urgent transplantation during the next 2 years. In 265 patients with ejection fraction < or = 25% and initial New York Heart Association class IV symptoms, survival at 2 years was 55% (without urgent transplantation, 45%). Lower cardiac index or higher filling pressures at the time of referral did not confer higher risk, which was predicted by persistence of higher pressures after therapy. Serum sodium below 133 was associated with 34% 2-year survival without urgent transplantation, and ventricular dimension > 80 mm with a rate of 25%. Patients with initial peak oxygen consumption > 10 mL/kg per minute had a 2-year event-free rate of 72% compared with 48% for those with < 10 mL/kg per minute and 32% for those unable to exercise at referral. Demonstration of a 30% decrease in mortality with a controlled trial of new therapy in patients with ejection fraction < or = 25% would require 600 patients with class III symptoms or almost 300 patients with class IV symptoms unless another criterion were added.

CONCLUSIONS

Ambulatory populations with high predicted event rates can be identified at initial evaluation, when hemodynamic criteria may be less useful than ventricular dimension, serum sodium, and ability to exercise. The use of outcome data from previous eras may lead to overestimation of benefits from newer therapies and underestimation of the sample size required in a prospective trials.

Evidence for preserved cardiopulmonary baroreflex control of renal cortical blood flow in humans with advanced heart failure. A positron emission tomography study

BACKGROUND

The effect of cardiopulmonary baroreflexes on the renal circulation in healthy humans and patients with heart failure is unknown because of the technical limitations of studying the renal circulation. Positron emission tomography (PET) imaging is a new method to measure renal cortical blood flow in humans that is precise, rapid, reproducible, and noninvasive. The purpose of this study was to compare the effect of acute cardiopulmonary baroreceptor unloading by phlebotomy on regional blood flow in healthy humans and humans with advanced heart failure.

METHODS AND RESULTS

We compared renal cortical blood flow and forearm blood flow in 10 healthy volunteers and 8 patients with heart failure (left ventricular ejection fraction, 0.24 +/- 0.02) during cardiopulmonary baroreceptor unloading with phlebotomy (450 mL). The major findings of this study are: (1) At rest, renal cortical blood flow is markedly diminished in humans with heart failure compared with healthy humans (heart failure, 2.4 +/- 0.1 versus healthy, 4.3 +/- 0.2 mL.min-1.g-1, P < .001). (2) In healthy humans, during phlebotomy, forearm blood flow decreased substantially (basal, 3.3 +/- 0.4 versus phlebotomy, 2.6 +/- 0.3 mL.min-1.100 mL-1, P = .02) and renal cortical blood flow decreased slightly but significantly (basal, 4.3 +/- 0.2 versus phlebotomy, 4.0 +/- 0.3 mL.min-1.g-1, P = .01). (3) The small magnitude of reflex renal vasoconstriction is not explained by the inability of the renal circulation to vasoconstrict, since the cold pressor stimulus induced substantial decreases in renal cortical blood flow in healthy subjects (basal, 4.4 +/- 0.1 versus cold pressor, 3.7 +/- 0.1 mL.min-1.g-1, P = .003). (4) In humans with heart failure, during phlebotomy, forearm blood flow did not change (basal, 2.6 +/- 0.3 versus phlebotomy, 2.7 +/- 0.2 mL.min-1.100 mL-1, P = NS), but renal cortical blood flow decreased slightly but significantly (basal, 2.4 +/- 0.1 versus phlebotomy, 2.1 +/- 0.1 mL.min-1.g-1, P = .01). (5) The cold pressor stimulus induced substantial decreases in renal cortical blood flow in patients with heart failure (basal, 2.9 +/- 0.1 versus cold pressor, 2.3 +/- 0.1 mL.min-1.g-1, P = .008). Thus, in patients with heart failure, there is an abnormality in cardiopulmonary baroreflex control of the forearm circulation but not the renal circulation.

CONCLUSIONS

This study demonstrates the power of PET imaging to study normal physiological and pathophysiological reflex control of the renal circulation in humans and describes the novel finding of selective dysfunction of cardiopulmonary baroreflex control of one vascular region but its preservation in another in patients with heart failure.

Hard surface carrier test as a quantitative test of disinfection: a collaborative study

The hard surface carrier test (HSCT) recently was proposed as a qualitative test for disinfectant efficacy. A collaborative study of HSCT led to a suggested performance standard of < or = 2 or 3 positive carriers out of 60 tested. Subsequently, it was discovered that HSCT can be used as a quantitative test, because the HSCT protocol requires measurement of inoculum level on some carriers. The data allow estimation of the log10 reduction in number of active bacteria. Producers, consumers, and policymakers will be better able to discuss merits of alternative performance standards if the focus is on log reduction of organisms rather than on number of positive carriers. Data from the collaborative study were reanalyzed from this quantitative viewpoint. If the point estimate of log reduction in LR and the 99% lower confidence limit estimate is LLR, the LR values ranged from 7.0 to 9.0 and the LLR values were greater than 6.0 for all disinfectants except the negative control formulation. The total variance for estimated LR is the sum of interlaboratory and intralaboratory variances. The total variance for LR was 0.095 for Pseudomonas aeruginosa, 0.251 for Staphylococcus aureus, and 0.118 for Salmonella choleraesuis. Percentages of the variance due to interlaboratory variability were 11% for P. aeruginosa, 52% for S. aureus, and 25% for S. choleraesuis. Chances of making false-effective and false-ineffective decisions can be calculated for the quantitative HSCT. The performance standard can be based on LLR.

The University of California at Los Angeles experience in heart transplantation

In the last decade, the number of patients undergoing heart transplantation has steadily increased as a result of expanding indications for cardiac transplantation. The limitation on the number of transplants performed has been the number of donor organs available. At UCLA, 511 heart transplant procedures were performed from 1984-1994. The mean number of rejection episodes and infections per patient in the first year after transplant was 1.1+/-1.3 and 1.0+/-1.2, respectively. Actuarial one-, 3-, and 5-year survival rates were 84%, 77% and 73%, respectively. Survival of patients age 60 years and over (n=105) was comparable to that of patients under age 60. Despite transplanting more critically ill patients (Status 1) and having longer cold ischemic times, outcomes have been improving. We have been pursuing corticosteroid-free immunosuppression, which no doubt has led to the decrease in infection complications. Furthermore, our work with pravastatin early after transplantation has led to a decrease in clinically severe rejection episodes which has translated into improved survival. Pravastatin also appeared to decrease the development of transplant coronary artery disease and appeared to have an adjunct immunosuppressive effect in our heart transplant patients on CsA-based immunosuppression. Future studies will include the use of mycophenolate mofetil which has properties against B-lymphocytes in addition to T-lymphocytes to block both humoral and cellular rejection. Our program continues to seek better ways to improve survival and the quality of life of our patient population.

Improvement in exercise capacity of candidates awaiting heart transplantation

OBJECTIVES

This study determined the frequency of improvement in peak oxygen uptake and its role in reevaluation of candidates awaiting heart transplantation.

BACKGROUND

Ambulatory candidates for transplantation usually wait > 6 months to undergo the procedure, and during this period symptoms may lessen, and peak oxygen uptake may improve. Whereas initial transplant candidacy is based increasingly on objective criteria, there are no established guidelines for reevaluation to determine who can leave the active waiting list.

METHODS

All ambulatory transplant candidates with initial peak oxygen uptake < 14 ml/kg per min were identified. Of 107 such patients listed, 68 survived without early deterioration or transplantation to undergo repeat exercise. A strategy of reevaluation using specific clinical criteria and exercise performance was tested to determine whether patients with improved oxygen uptake could safely be followed without transplantation.

RESULTS

In 38 of the 68 patients, peak oxygen uptake increased by > or = 2 ml/kg per min to a level > or = 12 ml/kg per min after 6 +/- 5 months, together with an increase in anaerobic threshold, peak oxygen pulse and exercise heart rate reserve and a decrease in heart rate at rest. Increased peak oxygen uptake was accompanied by stable clinical status without congestion in 31 of 38 patients, and these 31 were taken off the active waiting list. At 2 years, their actuarial survival rate was 100%, and the survival rate without relisting for transplantation was 85%.

CONCLUSION

Reevaluation of exercise capacity and clinical status allowed removal of 31 (29%) of 107 ambulatory transplant candidates from the waiting list with excellent early survival despite low peak oxygen uptake on initial testing. The ability to increase peak oxygen uptake, particularly with increased peak oxygen pulse, may indicate improved prognosis as well as functional capacity and, in combination with stable clinical status, may be an indication to defer transplantation in favor of more compromised candidates.

Independent control of skin and muscle sympathetic nerve activity in patients with heart failure

BACKGROUND

Sympathetic excitation characterizes heart failure, but the underlying mechanisms remain unknown. Abnormal baroreflex restraint of sympathetic neural outflow has been proposed, since baroreflexes are known to be abnormal in heart failure. The purpose of this study was to determine if sympathetic activation in humans with heart failure is limited to regions governed by the baroreflexes or is generalized to other regions free from baroreflex control.

METHODS AND RESULTS

We report the first direct recordings of skin sympathetic nerve activity (free from baroreflex control) in humans with heart failure and compare simultaneous skin and muscle (baroreflex-dependent) sympathetic peroneal nerve activity in six patients with severe heart failure (mean left ventricular ejection fraction, 0.19 +/- 0.06) and in six age-matched normal control subjects. Although muscle sympathetic nerve activity was markedly increased in heart failure patients (heart failure versus controls, 69 +/- 3 versus 21 +/- 2 bursts per minute; P < .001), skin sympathetic nerve activity was not increased (heart failure versus controls, 12 +/- 1 versus 15 +/- 1 bursts per minute; P = NS).

CONCLUSIONS

The finding that skin sympathetic nerve activity in contrast to muscle sympathetic nerve activity is not increased in heart failure supports the concept that an altered reflex system, such as the baroreflexes, with nonuniform effects on muscle and skin sympathetic nerve activity, underlies sympatho-excitation in heart failure.

Prediction of improvement in recent onset cardiomyopathy after referral for heart transplantation

OBJECTIVES

The purpose of this investigation was to determine how often left ventricular function improves in recent onset dilated cardiomyopathy of sufficient severity to cause referral for heart transplantation and how to predict this improvement at the time of evaluation for transplantation.

BACKGROUND

Improvement has been reported to occur frequently in patients with acute dilated cardiomyopathy but has not been described specifically in these patients referred for transplantation. To avoid potentially needless transplantation, it would be useful to know the frequency of improvement and how to predict it in these patients.

METHODS

A consecutive series of 297 patients with primary dilated cardiomyopathy evaluated for heart transplantation was reviewed to identify those with onset of heart failure symptoms within the preceding 6 months and to examine their outcome. The clinical, echocardiographic, hemodynamic and laboratory profiles of patients with improvement in left ventricular function (defined as an increase in left ventricular ejection fraction > or = 0.15 to a final ejection fraction of > or = 0.30) were compared with those of patients without improvement to assess which variables might predict improvement.

RESULTS

Of 49 patients with recent onset dilated cardiomyopathy, 13 (27%) showed improvement, with an increase in mean left ventricular ejection fraction from 0.22 +/- 0.08 to 0.49 +/- 0.09. All patients with improvement had survived without heart transplantation at 43 +/- 29 months. Survival time was shorter in the remaining 36 patients without improvement with recent onset cardiomyopathy than in the 248 with chronic symptoms (p = 0.03) and in younger compared with older patients with recent onset cardiomyopathy (p = 0.0001). By multivariate analysis, predictors of improvement were shorter duration of symptoms, lower pulmonary wedge and right atrial pressures and higher serum sodium levels.

CONCLUSIONS

A minority of patients with dilated cardiomyopathy and symptoms for < or = 6 months will have marked improvement in left ventricular function, after which prognosis is excellent despite previous referral for heart transplantation. Those with symptom duration > 3 months and more severe initial decompensation as reflected by higher filling pressures and lower serum sodium levels are unlikely to show improvement and may require earlier consideration for heart transplantation.

The impending crisis awaiting cardiac transplantation. Modeling a solution based on selection

BACKGROUND

Each month, the number of transplant candidates added to the waiting list exceeds the number of transplantations performed, and many outpatients deteriorate to require transplantation urgently. The current list of 2400 candidates and the average wait of 8 months continue to increase.

METHODS AND RESULTS

To determine the size at which the outpatient and critical candidate pools will stabilize, population models were constructed using current statistics for donor hearts, candidate listing, sudden death, and outpatient decline to urgent status and revised to predict the impact of alterations in policies of candidate listing. If current practices continue, within 48 months the predicted list will stabilize as the sum of an estimated 270 hospitalized candidates, among whom, together with newly listed urgent candidates, all hearts will be distributed and 3700 outpatient candidates with virtually no chance of transplantation unless they deteriorate to an urgent status. Decreasing the upper age limit now to 55 years would reduce the number listed each month by 30% and result within 48 months in a list of only 1490. The list could also be decreased by 30%, however, if it were possible to list only a candidate group with an 80% chance (compared with 52% estimated currently) of sudden death or deterioration during the next year. With this strategy, the waiting list would equilibrate within 48 months to one-third the current size, with 50% of hearts for outpatient candidates, who would then have an 11% chance each month of receiving a heart compared with 0% if recent policies prevail. Total deaths, with and without transplantation, would be minimized by this rigorous selection of outpatient candidates.

CONCLUSIONS

This study implies that immediate provisions should be made to limit candidate listing and revise expectations to reflect the diminishing likelihood of transplantation for outpatient candidates. Future emphasis should be on improved selection of candidates at highest risk without transplantation.

Impact of left ventricular cavity size on survival in advanced heart failure

Although left ventricular (LV) dilation has been assumed to be deleterious, the physiologic significance of severe LV dilation in advanced heart failure and its impact on survival have not been defined. LV end-diastolic dimension was measured by M-mode echocardiography in 382 patients with class III or IV heart failure symptoms (mean LV ejection fraction 20 +/- 8%) referred for evaluation for cardiac transplantation. All patients underwent right-sided heart catheterization, and received vasodilator and diuretic therapy adjusted to hemodynamic goals. Although 183 patients with massive LV dilation by LV index > 4 cm/m2 (LV index = LV end-diastolic dimension/estimated body surface area) had a similar severity of hemodynamic impairment to that of 199 patients with only moderate dilation (LV index < or = 4 cm/m2), with baseline mean cardiac index of 2 liters/m/m2 and mean pulmonary arterial wedge pressure of 26 mm Hg in both groups, their actuarial 2-year survival without transplantation was much lower (49 vs 75%; p = 0.004). In the Cox proportional-hazards model, LV index predicted total and sudden death, independent of etiology of heart failure, ejection fraction and other parameters of disease severity. Follow-up echocardiograms (mean 13 +/- 6 months) in 80 heart failure survivors without transplantation showed an increase in mean LV ejection fraction (22 +/- 8% to 26 +/- 13%), but no change in mean LV index in either the massive or moderately dilated groups. Thus, massive LV dilation is an independent contributor to poor outcome in patients with advanced heart failure, and may be stabilized by aggressive vasodilator and diuretic therapy.

Prevalence and clinical implications of abnormal thyroid hormone metabolism in advanced heart failure

Patients with advanced congestive heart failure are often severely ill and may experience substantial abnormalities in thyroid hormone metabolism. Thus, we examined this patient population to determine the prevalence and prognostic significance of altered thyroid hormone concentrations, the course of thyroid abnormalities in congestive heart failure survivors, and the potential relationship of thyroid abnormalities to overall metabolic rate. Our results indicate that thyroid hormone metabolism (ie, the triiodothyronine to reverse triiodothyronine ratio) is altered in a majority of patients with advanced congestive heart failure and is an independent predictor of mortality. Currently a study is underway that will provide further evidence for the mechanisms involved in congestive heart failure and abnormal thyroid hormone metabolism.

Sociology-the poor relation in alcohol and drug research?

As a foundation theoretical discipline, sociology has much to offer the multi-disciplinary field of alcohol and drug studies. It has, nevertheless, been overshadowed by others such as medicine and, more recently, psychology. This paper maps significant policy issues in the alcohol and drug field over the past decade using Australian experience as an example. It identifies contributions of the social sciences and in doing so, poses a challenge for sociology.