Ophthalmic findings associated with Australian tick paralysis (holocyclotoxicity) in hospitalized domestic dogs and cats

OBJECTIVE

To describe ophthalmic findings in hospitalized canine and feline patients with tick paralysis (TP) and investigate possible predisposing factors.

ANIMALS STUDIED

Forty-seven dogs and 28 cats hospitalized with TP assessed with an ophthalmic examination performed by an ABVO resident.

METHODS

Dogs and cats were hospitalized with TP from October 2021 to January 2022 and had an ophthalmic examination performed by an ABVO resident. Patient signalment data, information regarding tick number and location, hospitalization duration, medications used, and patient paralysis grades were recorded. Statistical analysis was performed to correlate findings.

RESULTS

Corneal ulcers developed in up to 34.8% of dogs and up to 42.9% of cats hospitalized with TP. An absent palpebral reflex ipsilaterally increased the odds of a concurrent corneal ulcer being present by 14.7× in dogs and 20.1× in cats (p < .0001). Palpebral reflexes were absent in 38.3% of dogs and 35.7% of cats hospitalized with TP and were correlated with more severe gait paralysis (p = .01) and respiratory paralysis (p = .005) in dogs, and respiratory paralysis in cats (p = .041). STT-1 findings <10 mm/min were present in 27.7% of dogs and 57.1% of cats examined and were associated with increasing gait paralysis (p = .017) and respiratory paralysis (p = .007) in dogs, and increasing gait paralysis in cats (p = .017).

CONCLUSIONS

Simple corneal ulcers, loss of a complete palpebral reflex, and reduced STT-1 scores frequently occurred in dogs and cats hospitalized for TP. The frequency of these findings increased as the degree of patient paralysis increased.

Feline distichiasis treated with cryoepilation: A retrospective study of 15 cats (27 eyes)

OBJECTIVE

To describe the clinical features of cats diagnosed with distichiasis and report on the outcomes following cryoepilation.

ANIMALS STUDIED

Fifteen cats (27 eyes).

PROCEDURES

Medical records of domestic cats with distichiasis that underwent a double freeze-thaw cycle with a -80°C cryoprobe applied to the palpebral conjunctiva, with hair then epilated were retrospectively studied. The patient signalment, distichiae locations, concurrent ocular diseases, recurrences, complications, and outcomes were recorded.

RESULTS

The mean (std dev) age at the time of diagnosis and treatment was 2.2 years (2.8 years). All (15/15) cats were of the domestic shorthair (DSH) breed. Concurrent ocular findings at the initial examination were observed in 17/27 (63%) eyes, with upper lateral eyelid hypoplasia the most prevalent, present in 9/27 (33.3%) eyes. Recurrence of distichiae occurred in 8/27 (29.6%) eyes. The clinical presentation in the instances of recurrence was judged as asymptomatic and not of a clinical concern in 3/27 (11.1%) eyes, with a second procedure deemed necessary to alleviate symptoms in 5/27 (18.5%) eyes. All eyes treated with a second procedure had no recurrence of distichiae or symptoms. Complications following cryoepilation occurred in 4/27 (14.8%) eyes, with two cats developing bilateral entropion post-procedure.

CONCLUSIONS

Treatment of distichiasis in cats utilizing cryoepilation was effective at alleviating symptoms, though some cats needed a second procedure. The development of post-procedural entropion was seen occasionally.

Retrospective assessment of ophthalmic disease development in domestic dogs and cats when hospitalised with tick paralysis caused by Ixodes holocyclus

OBJECTIVE

To investigate the incidence and predisposing factors leading to the development of corneal ulcers and the loss of a palpebral reflex in hospitalised canine and feline patients with tick paralysis (TP).

ANIMALS STUDIED

A total of 102 dogs and 100 cats retrospectively were assessed from previously hospitalised patients.

METHODS

A retrospective cohort study was performed on 102 different canine and 100 different feline patients who were hospitalised for TP from October 2020-January 2022. Patient data were collected, and logistic regression was conducted to determine factors affecting the palpebral reflex and the development of corneal ulcers.

RESULTS

Corneal ulcers occurred in 23/102 (22.5%) dogs during hospitalisation and were strongly associated with an incomplete palpebral reflex ipsilaterally during hospitalisation (P < 0.001), hospitalisation ≥3 days (P = 0.004), mechanical ventilation ≥3 days (P = 0.015) or a tick location cranial to C1 (P = 0.003). An incomplete palpebral reflex during hospitalisation was observed in 29/102 (28.4%) dogs and was significantly associated with decreasing patient weight (P = 0.018), increasing days hospitalised (P = 0.001), having a tick found cranial to C1 (P = 0.004), highest recorded GP grade (P = 0.01), highest recorded RP grade (P = 0.005), use of amoxycillin-clavulanic acid during hospitalisation (P = 0.002) and use of piperacillin/tazobactam during hospitalisation (P = 0.003). There was a significant association between the loss of a complete palpebral reflex and mortality during hospitalisation in dogs (OR = 4.5, P = 0.029). Corneal ulcers occurred in 10/100 (10.0%) cats during hospitalisation, and was significantly more likely to occur to an eye if an incomplete palpebral reflex was observed ipsilaterally during hospitalisation (OR = 20.1, P < 0.0001) and with increasing patient age (P = 0.019). The absence of a complete palpebral reflex during hospitalisation was observed in 18/10 (18.0%) cats and was significantly associated with increasing days hospitalised (P = 0.034). There was no significant association between the loss of a complete palpebral reflex and mortality during hospitalisation in cats.

CONCLUSIONS

The frequency of corneal ulcers and loss of palpebral reflexes were significant in dogs and cats hospitalised by TP, with many factors contributing to the risk of these developing.

Initial clinical experience with Myxo-ETlogix mitral valve repair ring

OBJECTIVE

Complexity of mitral valve repair for myxomatous disease has led to low adoption. We report initial experience with a new ring designed specifically for myxomatous disease, the Myxo-ETlogix (Edwards Lifesciences LLC, Irvine, Calif).

METHODS

From March 15, 2006, through November 19, 2007, 129 patients underwent mitral valve surgery for pure myxomatous disease, and 124 valves (96.1%) were repaired. The Myxo-ETlogix ring was used in 100 cases and the Physio ring (Edwards) in 24. The Myxo-ETlogix design includes a 3-dimensional shape to reduce systolic anterior motion and a larger orifice to accommodate elongated leaflets and decrease need for sliding plasty. Direct mitral valve measurements were made. Sizing was based on A2 height, and choice of ring type was based on unresected leaflet heights.

RESULTS

There was no operative mortality or lasting perioperative morbidity. The Myxo-ETlogix group had taller A2, P1, P2, and P3 leaflet segments than the Physio group (P < or = .003). Only 1 sliding plasty was performed for asymmetry in the Myxo-ETlogix group. Predischarge and follow-up echocardiograms (n = 338 in 124 patients) disclosed transient nonobstructive chordal systolic anterior motion in 3 echocardiograms in 3 patients. No patients had 2+ or greater mitral regurgitation. At discharge, 5.7% had 1+ mitral regurgitation; this proportion was 17.3% at last follow-up (mean 6.1 +/- 4.4 months).

CONCLUSION

In initial experience with the Myxo-ETlogix ring, nonobstructive systolic anterior motion has been rare and obstructive systolic anterior motion not observed. Ongoing prospective echocardiographic and clinical studies will elucidate the role of this etiology-specific ring.

Early and Late Rejection and HLA Sensitization at the Time of Heart Transplantation in Patients Bridged With Left Ventricular Assist Devices

Over the years, the frequency of heart transplant candidates with HLA sensitization has increased as a result of the number of patients bridged to transplant using left ventricular assist devices (LVAD). Here we have examined 119 patients who were bridged to transplant with LVAD for a relationship between HLA antibodies and early (30 days) and late (2 years or more) rejection, as evidenced by endomyocardial biopsies. Both cytotoxic panel-reactive antibody reactions against a panel of T lymphocytes (T-PRA) and the percentage of transplants that occurred across a positive class I flow cross-match were examined. Biopsies were scored using ISHLT criteria. At 30 days, patients who had a biopsy grade of 0 had a mean T-PRA at transplant of 2.2%, while the mean PRAs of the other biopsy grades were significantly higher (P < .001). A similar pattern was seen with the highest biopsy results at 2 years or later (P < .001). None of the patients who had a grade 0 biopsy at 30 days posttransplant had a positive flow cytometry class I cross-match (P = .02), although the same pattern did not occur later due to a small number of patients (n = 3) who had negative biopsies. Thus, when biopsy results were examined early or late posttransplant, patients with negative biopsy results tended to have less HLA sensitization. While the methods of HLA sensitization involve humoral responses, more aggressive immunosuppression might be warranted to attempt to reduce cellular rejection posttransplant if HLA class I antibodies are present at the time of transplant.

Curative surgery for atrial fibrillation. Current status and minimally invasive approaches

Atrial fibrillation (AF) is the most common disorder of heart rhythm. Affecting 2.2 million Americans and millions more worldwide, AF is a dangerous and costly epidemic. AF is associated with an increased risk of stroke, premature death, and billions of dollars in health care expenditures. Traditional treatments of AF, which include medications aimed at rate or rhythm control, have been disappointing, leaving most patients in AF and failing to eliminate the risk of stroke. In contrast, advances in surgical and catheter-based therapies offer the chance to cure AF. With more than a decade of experience, surgical treatment AF is the most effective means of curing this arrhythmia. The classic Maze procedure eliminates AF in more than 90% of patients. A complex but safe operation, the Maze procedure is applied by relatively few surgeons. Recently, however, there has been a resurgence of interest in surgical treatment of AF. Advances in the understanding of the pathogenesis of AF and development of new ablation technologies enable surgeons to perform pulmonary vein ablation and create linear left atrial lesions rapidly and safely. Such procedures, which are generally applied to patients with AF and valvular heart disease, add 15 minutes to operative time and cure AF in approximately 80% of patients. New ablation technologies have been adapted to enable thoracoscopic and minimally invasive surgical AF ablation in patients with isolated AF, extending the possibility of cure to large numbers of patients.

Preload-adjusted maximal power: a novel index of left ventricular contractility in atrial fibrillation

BACKGROUND

Left ventricular contractility in atrial fibrillation is known to change in a beat to beat fashion, but there is no gold standard for contractility indices in atrial fibrillation, especially those measured non-invasively.

OBJECTIVE

To determine whether the non-invasive index of contractility "preload-adjusted PWR(max)" (maximal ventricular power divided by the square of end diastolic volume) can accurately measure left ventricular contractility in a beat to beat fashion in atrial fibrillation.

METHODS

Atrial fibrillation was induced experimentally using 60 Hz stimulation of the atrium and maintained in 12 sheep; four received diltiazem, four digoxin, and four no drugs (control). Aortic flow, left ventricular volume, and left ventricular pressure were monitored simultaneously. Preload-adjusted PWR(max), the slope of the end systolic pressure-volume relation (E(max)), and the maximum rate of change of left ventricular pressure (dP/dt(max)) were calculated in a beat to beat fashion.

RESULTS

Preload-adjusted PWR(max) correlated linearly with load independent E(max) (p < 0.0001) and curvilinearly with load dependent dP/dt(max) (p < 0.0001), which suggested the load independence of preload-adjusted PWR(max). After five minutes of diltiazem administration, preload-adjusted PWR(max), dP/dt(max), and E(max) fell significantly (p < 0.0001) to 62%, 64%, and 61% of baseline, respectively. Changes were not significant after five minutes of digoxin (103%, 98%, and 102%) or in controls (97%, 96%, and 95%).

CONCLUSIONS

Preload-adjusted PWR(max) correlates linearly with E(max) and is a useful measure of contractility even in atrial fibrillation. Non-invasive application of this method, in combination with echocardiography and tonometry, may yield important information for optimising the treatment of patients with atrial fibrillation.

Left ventricular assist device as a bridge to recovery: present status

A new application for left ventricular assist devices (LVAD) is as a bridge to recovery. In the settings of myocarditis and dilated cardiomyopathy, LVAD support is accompanied by marked hemodynamic, neurohormonal, physiologic, cellular, and molecular changes indicative of recovery. Despite these changes, experience with clinical successes is limited. Further studies of topics such as the timing of LVAD implantation and explantation, adjunct medical and surgical therapy, and optimum LVAD weaning protocols might help improve the success of this promising technology.

A simple method of left ventricular reconstruction without patch for ischemic cardiomyopathy

Interest in reconstructive surgery for ischemic cardiomyopathy has increased. We prospectively studied patients undergoing left ventricular reconstruction for ischemic cardiomyopathy. This report describes our technique for no-patch repair of left anterior descending aneurysms or akinetic areas. Patients are selected for surgery with discreet left anterior descending scar, usually detected by preoperative magnetic resonance imaging scan and three-dimensional echocardiography, with compensated heart failure or other indications for surgery such as severe coronary artery disease or mitral regurgitation.

Safety and efficacy of intraarterial thrombolysis for perioperative stroke after cardiac operation

BACKGROUND

Acute ischemic stroke after cardiac operations is a devastating complication with limited therapeutic options. As clinical trials of thrombolysis for acute ischemic stroke exclude patients with recent major surgery, the safety of intraarterial thrombolysis in this setting is unknown.

METHODS

Thirteen patients with acute ischemic stroke within 12 days of cardiac operation underwent intraarterial thrombolysis within 6 hours of stroke symptom onset. The National Institutes of Health Stroke Scale was used to assess neurologic recovery.

RESULTS

The mean age was 69 years (standard deviation +/-5 years) and 62% were men. Cardiac procedures included valve operations in 6 patients, coronary artery bypass grafting in 4, valve and coronary artery bypass grafting in 2, and left ventricular assist device in 1 patient. Atrial fibrillation occurred in 5 patients (38%). The mean time from operation to stroke was 4.3 days (standard deviation +/- 3 days). Thrombolysis was initiated within 3.6 hours (standard deviation +/-1.6 hours) of stroke symptom onset. Recanalization was complete in 1 patient, partial in 5, and 7 patients had low flow. Neurologic improvement occurred in 5 patients (38%). One patient needed a chest tube for hemothorax, 2 others were transfused for low hemoglobin. No operative intervention for bleeding was necessary.

CONCLUSIONS

In select patients with acute ischemic stroke after recent cardiac operation, intraarterial thrombolysis appears to be reasonably safe and may lead to neurologic recovery.

Is repair preferable to replacement for ischemic mitral regurgitation?

OBJECTIVE

This study was undertaken to compare mitral valve repair and replacement as treatments for ischemic mitral regurgitation.

METHODS

From 1985 through 1997, a total of 482 patients with ischemic mitral regurgitation underwent either valve repair (n = 397) or valve replacement (n = 85). Patients more likely (P < or =.01) to undergo repair had functional mitral regurgitation or coronary revascularization with an internal thoracic artery graft; those more likely to receive valve replacement were in higher New York Heart Association functional classes or underwent emergency operations. These factors were used for multivariable propensity matching. Risk factors for early and late death were identified by multivariable, multiphase hazard function analysis.

RESULTS

Within the propensity-matched better-risk group, survivals after valve replacement were 81%, 56%, and 36% at 30 days, 1 year, and 5 years, but survivals after repair were 94%, 82%, and 58% at these intervals (P =.08). In contrast, within the poor-risk group, survivals after repair and replacement were similar (P =.4). Risk factors (P < or =.01) included older age, higher functional class, greater wall motion abnormality, and renal dysfunction. Approximately 70% of patients were predicted to benefit from repair; the benefit lessened or was negated if an internal thoracic artery graft was not used, if a lateral wall motion abnormality was present, or if the mitral regurgitation jet pattern was complex. Freedom from repair failure at 5 years was 91%.

CONCLUSION

Late survival is poor after surgery for ischemic mitral regurgitation. Most patients with ischemic mitral regurgitation benefit from mitral valve repair. In the most complex, high-risk settings, survivals after repair and replacement are similar.

Surgical treatments for heart failure

The surgical options for CHF are a part of a larger paradigm shift in management. Viable and effective surgical options other than cardiac transplant and ventricular assist devices clearly exist and are applicable to a large portion of patients with CHF. These surgical therapies are of acceptable risk before decompensated CHF develops. The rapidly evolving therapies for altering LV remodeling, which underlies CHF progression, are an exciting area that may be joined in the future by molecular advances in myoblast transfer and gene therapy. These therapies are the basis of the discipline of CHF surgery within cardiovascular surgery.

Relationship between early diastolic intraventricular pressure gradients, an index of elastic recoil, and improvements in systolic and diastolic function

BACKGROUND

Early diastolic intraventricular pressure gradients (IVPGs) have been proposed to relate to left ventricular (LV) elastic recoil and early ventricular "suction." Animal studies have demonstrated relationships between IVPGs and systolic and diastolic indices during acute ischemia. However, data on the effects of improvements in LV function in humans and the relationship to IVPGs are lacking.

METHODS AND RESULTS

Eight patients undergoing CABG and/or infarct exclusion surgery had a triple-sensor high-fidelity catheter placed across the mitral valve intraoperatively for simultaneous recording of left atrial (LA), basal LV, and apical LV pressures. Hemodynamic data obtained before bypass were compared with those with similar LA pressures and heart rates obtained after bypass. From each LV waveform, the time constant of LV relaxation (tau), +dP/dt(max), and -dP/dt(max) were determined. Transesophageal echocardiography was used to determined end-diastolic (EDV) and end-systolic (ESV) volumes and ejection fractions (EF). At similar LA pressures and heart rates, IVPG increased after bypass (before bypass 1.64+/-0.79 mm Hg; after bypass 2.67+/-1.25 mm Hg; P<0.01). Significant improvements were observed in ESV, as well as in apical and basal +dP/dt(max), -dP/dt(max), and tau (each P<0.05). Overall, IVPGs correlated inversely with both ESV (IVPG=-0.027[ESV]+3.46, r=-0.64) and EDV (IVPG=-0.027[EDV]+4.30, r=-0.70). Improvements in IVPGs correlated with improvements in apical tau (Deltatau =5.93[DeltaIVPG]+4.76, r=0.91) and basal tau (Deltatau =2.41[DeltaIVPG]+5.13, r=-0.67). Relative changes in IVPGs correlated with changes in ESV (DeltaESV=-0.97[%DeltaIVPG]+23.34, r=-0.79), EDV (DeltaEDV=-1.16[%DeltaIVPG]+34.92, r=-0.84), and EF (DeltaEF=0.38[%DeltaIVPG]-8.39, r=0.85).

CONCLUSIONS

Improvements in LV function also increase IVPGs. These changes in IVPGs, suggestive of increases in LV suction and elastic recoil, correlate directly with improvements in LV relaxation and ESV.

Ascorbate attenuates atrial pacing-induced peroxynitrite formation and electrical remodeling and decreases the incidence of postoperative atrial fibrillation

Atrial fibrillation (AF), the most common chronic arrhythmia, increases the risk of stroke and is an independent predictor of mortality. Available pharmacological treatments have limited efficacy. Once initiated, AF tends to self-perpetuate, owing in part to electrophysiological remodeling in the atria; however, the fundamental mechanisms underlying this process are still unclear. We have recently demonstrated that chronic human AF is associated with increased atrial oxidative stress and peroxynitrite formation; we have now tested the hypothesis that these events participate in both pacing-induced atrial electrophysiological remodeling and in the occurrence of AF following cardiac surgery. In chronically instrumented dogs, we found that rapid (400 min(-1)) atrial pacing was associated with attenuation of the atrial effective refractory period (ERP). Treatment with ascorbate, an antioxidant and peroxynitrite decomposition catalyst, did not directly modify the ERP, but attenuated the pacing-induced atrial ERP shortening following 24 to 48 hours of pacing. Biochemical studies revealed that pacing was associated with decreased tissue ascorbate levels and increased protein nitration (a biomarker of peroxynitrite formation). Oral ascorbate supplementation attenuated both of these changes. To evaluate the clinical significance of these observations, supplemental ascorbate was given to 43 patients before, and for 5 days following, cardiac bypass graft surgery. Patients receiving ascorbate had a 16.3% incidence of postoperative AF, compared with 34.9% in control subjects. In combination, these studies suggest that oxidative stress underlies early atrial electrophysiological remodeling and offer novel insight into the etiology and potential treatment of an enigmatic and difficult to control arrhythmia. The full text of this article is available at http://www.circresaha.org.

Nosocomial bloodstream infections in patients with implantable left ventricular assist devices

BACKGROUND

Implantable left ventricular assist devices (LVAD) are used as a bridge to transplantation but are associated with a high risk of infection including nosocomial bloodstream infections (BSI).

METHODS

We retrospectively reviewed the medical records of all patients with implantable LVAD at the Cleveland Clinic with 72 hours or longer of LVAD support from January 1992 through June 2000, to determine the attack rate, incidence, and impact of nosocomial BSI in patients with LVAD. A nosocomial BSI was defined using Centers for Disease Control and Prevention definition. An LVAD-related BSI was defined as one where the same pathogen is cultured from the device and the blood with no other obvious source. Two hundred fourteen patients were included in the study (17,831 LVAD-days).

RESULTS

One hundred forty BSI were identified in 104 patients for an attack rate of 49% and incidence of 7.9 BSI per 1000 LVAD-days. Thirty-eight percent of the BSI were LVAD associated. The most common pathogens causing BSI were coagulase-negative staphylococci (n = 33), Staphylococcus aureus, and Candida spp. (19 each), and Pseudomonas aeruginosa (16 each). A Cox proportional hazard model found BSI in patients with LVAD to be significantly associated with death (hazard ratio = 4.02, p < 0.001). Fungemia had the highest hazard ratio (10.9), followed by gram-negative bacteremia (5.1), and gram-positive bacteremia (2.2).

CONCLUSIONS

Patients with implantable LVAD have a high incidence of BSI, which are associated with a significantly increased mortality. Strategies for prevention of infection in LVAD recipients should focus on the drive line exit site until technical advances can achieve a totally implantable device.

Device-based change in left ventricular shape: a new concept for the treatment of dilated cardiomyopathy

OBJECTIVE

We tested a unique new device, the Myosplint device (Myocor, Inc, Maple Grove, Minn), which is designed to change left ventricular shape, reduce left ventricular wall stress, and improve left ventricular systolic function.

METHODS

Heart failure was induced in 15 dogs over 27 days by rapid pacing (230 beats/min). Seven animals underwent sham surgery, and 8 animals received 3 transventricular Myosplint devices each. Myosplint devices were tightened to create a symmetric bilobular left ventricular shape and were adjusted to produce a calculated 20% reduction in wall stress. Hemodynamic, 2-dimensional, and 3-dimensional echocardiographic studies were recorded at baseline, immediately after Myosplint placement (acute change), and at 1 month after both groups had a reduced rate (190 beats/min) of pacing designed to maintain heart failure.

RESULTS

The Myosplint group had significant sustained improvements in left ventricular ejection fraction from baseline, to the acute change, to 1 month (19% +/- 5%; 36% +/- 8%; 39% +/- 13%) and reductions of left ventricular end-systolic volumes (73 +/- 9 mL; 34 +/- 5 mL; 42 +/- 12 mL) and end-systolic wall stress by 39% (341 +/- 68 10(3) dynes x cm(- 2) to 206 +/- 28 10(3) dynes x cm(-2)) acutely and 31% (372 +/- 83 10(3) dynes x cm(-2) to 250 +/- 40 10(3) dynes x cm(-2)) at 1 month. There were no significant changes in mitral regurgitation.

CONCLUSION

Application of a Myosplint device to a dilated impaired left ventricle resulted in reduced wall stress and improved left ventricular systolic function that was sustained at 1 month. Device-based shape change is a promising new opportunity to treat patients with dilated cardiomyopathy.

Mechanical unloading restores beta-adrenergic responsiveness and reverses receptor downregulation in the failing human heart

BACKGROUND

Mechanical unloading of the failing human heart with a left ventricular assist device (LVAD) results in clinically documented reversal of chamber dilation and improvement of cardiac function. We tested the hypothesis that LVAD support normalizes the ability of cardiac muscle to respond to sympathetic nervous system stimulation by reversing the downregulation of beta-adrenergic receptors.

METHODS AND RESULTS

Human LV tissue was obtained from nonfailing hearts of unmatched organ donors and failing hearts at the time of transplantation, with or without LVAD. Baseline contractile parameters and inotropic response to a beta-adrenergic agonist were measured in isolated trabecular muscles. beta-Adrenergic receptor density was quantified by radioligand binding. Results showed a significant increase in the response to beta-adrenergic stimulation after LVAD (developed tension increased by 0.76+/-0.09 g/mm(2) in nonfailing, 0.38+/-0.07 in failing, and 0.68+/-0.10 in failing+LVAD; P<0.01), accompanied by an increased density of beta-adrenergic receptors (58.7+/-9.6 fmol/mg protein in nonfailing, 26.2+/-3.8 in failing, and 63.0+/-8.3 in failing+LVAD; P<0.05). These changes were unrelated to the duration of support.

CONCLUSIONS

Data demonstrate that mechanically supporting the failing human heart with an LVAD can reverse the downregulation of beta-adrenergic receptors and restore the ability of cardiac muscle to respond to inotropic stimulation by the sympathetic nervous system. This indicates that functional impairment of cardiac muscle in human heart failure is reversible.

Impaired myofibrillar energetics and oxidative injury during human atrial fibrillation

BACKGROUND

Atrial fibrillation (AF) is associated with severe contractile dysfunction and structural and electrophysiological remodeling. Mechanisms responsible for impaired contractility are undefined, and current therapies do not address this dysfunction. We have found that myofibrillar creatine kinase (MM-CK), an important controller of myocyte contractility, is highly sensitive to oxidative injury, and we hypothesized that increased oxidative stress and energetic impairment during AF could contribute to contractile dysfunction. Methods and Results-- Right atrial appendages were obtained from AF patients undergoing the Maze procedure and from control patients who were in normal sinus rhythm and undergoing cardiac surgery. MM-CK activity was reduced in AF patients compared with controls (25.4+/-3.4 versus 18.2+/-3.8 micromol/mg of myofibrillar protein per minute; control versus AF; P<0.05). No reduction in total CK activity or myosin ATPase activity was detected. This selective reduction in MM-CK activity was associated with increased relative expression of the beta-myosin isoform (25+/-6 versus 63+/-5%beta, CTRL versus AF; P<0.05). Western blotting of AF myofibrillar isolates demonstrated no changes in protein composition but showed increased prevalence of protein oxidation as detected by Western blotting for 3-nitrotyrosine (peroxynitrite biomarker) and protein carbonyls (hydroxyl radical biomarker; P<0.05). Patterns of these oxidative markers were distinct, which suggests discrete chemical events and differential protein vulnerabilities in vivo. MM-CK inhibition was statistically correlated to extent of nitration (P<0.01) but not to carbonyl presence.

CONCLUSIONS

The present results provide novel evidence of oxidative damage in human AF that altered myofibrillar energetics may contribute to atrial contractile dysfunction and that protein nitration may be an important participant in this condition.

A novel miniature ventricular assist device for hemodynamic support

The HemoDynamics Systems enabler is a new cardiac assist pump that can expel blood from the left ventricle and provide pulsatile flow in the aorta. We evaluated the efficacy of the 18 Fr enabler. The enabler was inserted from the left ventricular apex into the ascending aorta in eight sheep. Heart failure (mild, moderate, and severe) was induced by microsphere injection into the coronary arteries to reduce cardiac output by 10-30%, 31-50%, and more than 50% from baseline, respectively. The enabler was activated, and its flow was increased to approximately 2.0 L/min. Hemodynamic variables were recorded before and after activation. In moderate heart failure, cardiac output and mean aortic pressure increased from 2.3 +/- 0.6 L/min and 59 +/- 12 mm Hg before assist to 2.8 +/- 0.6 L/min and 70 +/- 8 mm Hg at 30 minutes after activation, respectively (p < 0.01). Left atrial pressure decreased from 17 +/- 3 to 13 +/- 4 mm Hg (p < 0.05). Similar findings were observed in mild and severe heart failure. Despite its small diameter, the enabler significantly improved the hemodynamics of failing hearts and may potentially serve as a means of peripheral left ventricular support. Further study is warranted.

Clinical experience with 202 adults receiving extracorporeal membrane oxygenation for cardiac failure: survival at five years

OBJECTIVES

We sought to determine 5-year survival after extracorporeal membrane oxygenation for cardiac failure and its predictors, to assess survival and its predictors after bridging to transplantation or weaning from extracorporeal membrane oxygenation, and to identify factors influencing the likelihood of these outcomes.

METHODS

Two hundred two adults (mean age, 55 +/- 14 years) were supported with extracorporeal membrane oxygenation between 1992 and July 1999 after cardiac failure. Follow-up extended to 7.5 years (mean, 3.8 +/- 2 years). Multivariable hazard function analysis identified predictors of survival, and logistic regression identified the determinants of bridging or weaning.

RESULTS

Survival at 3 days, 30 days, and 5 years was 76%, 38%, and 24%, respectively. Patients surviving 30 days had a 63% 5-year survival. Risk factors (P <.1) included older age, reoperation, and thoracic aorta repair. Forty-eight patients were bridged to transplantation, and 71 were weaned with intent for survival. Survival was similar after either outcome (44% vs 40% 5-year survival, respectively). Failure to bridge or wean included (P <.03) renal and hepatic failure on extracorporeal membrane oxygenator support, occurrence of a neurologic event, and absence of infection. The dominant modes of death were cardiac failure and multisystem organ failure.

CONCLUSIONS

Extracorporeal membrane oxygenation is versatile and salvages some patients who would otherwise die. Improvement in intermediate-term outcome will require a multidisciplinary approach to protect organ function and limit organ injury before and during this support.

High prevalence of coronary atherosclerosis in asymptomatic teenagers and young adults: evidence from intravascular ultrasound

BACKGROUND

Most of our knowledge about atherosclerosis at young ages is derived from necropsy studies, which have inherent limitations. Detailed, in vivo data on atherosclerosis in young individuals are limited. Intravascular ultrasonography provides a unique opportunity for in vivo characterization of early atherosclerosis in a clinically relevant context.

METHODS AND RESULTS

Intravascular ultrasound was performed in 262 heart transplant recipients 30.9+/-13.2 days after transplantation to investigate coronary arteries in young asymptomatic subjects. The donor population consisted of 146 men and 116 women (mean age of 33.4+/-13.2 years). Extensive imaging of all possible (including distal) coronary segments was performed. Sites with the greatest and least intimal thickness in each CASS segment were measured in multiple coronary arteries. Sites with intimal thickness >/=0.5 mm were defined as atherosclerotic. A total of 2014 sites within 1477 segments in 574 coronary arteries (2.2 arteries per person) were analyzed. An atherosclerotic lesion was present in 136 patients, or 51.9%. The prevalence of atherosclerosis varied from 17% in individuals <20 years old to 85% in subjects >/=50 years old. In subjects with atherosclerosis, intimal thickness and area stenosis averaged 1.08+/-0.48 mm and 32.7+/-15.9%, respectively. For all age groups, the average intimal thickness was greater in men than women, although the prevalence of atherosclerosis was similar (52% in men and 51.7% in women).

CONCLUSIONS

This study demonstrates that coronary atherosclerosis begins at a young age and that lesions are present in 1 of 6 teenagers. These findings suggest the need for intensive efforts at coronary disease prevention in young adults.

Management strategies for high-risk cardiac surgery: improving outcomes in patients with heart failure

BACKGROUND

Surgical heart failure management is the fastest growing aspect of cardio-vascular surgery. Advances in cardiac surgical techniques have changed the number and types of operations permitted physicians and thus broadened the complexity of patients recommended for operation.

METHODS

Surgeons, anesthesiologists and cardiologists face hemodynamic and patho-physiological challenges that can be optimally overcome only by modifying treatment strategies. Because many treatment standards are still evolving in this rapidly advancing field, a team of cardiovascular surgeons and anesthesiologists convened to share clinical experience and impressions and discuss practical issues related to high-risk patients undergoing heart surgery.

RESULTS

Heart failure pathophysiology, surgical heart failure management, including mitral reconstruction and left ventricular remodeling, cardiopulmonary bypass weaning, inotropic support, transesophageal echocardiography and acute cardiovascular collapse after cardiac surgery are discussed.

CONCLUSION

This article is intended to guide clinicians to improve patient care and outcomes in this special population by providing specific guidance on the appropriate use of inotropic and mechanical support in patients undergoing high-risk procedures using innovative techniques.

Partial left ventriculectomy for dilated cardiomyopathy: is this an alternative to transplantation?

OBJECTIVE

To determine the late effectiveness of partial left ventriculectomy and risk factors for failure.

METHODS

Between May 1996 and December 1998, partial left ventriculectomy and concomitant mitral valve surgery were performed in 62 patients (95% transplant candidates) with a mean age of 54 years (range 17-72 years). All patients were in New York Heart Association functional class III (38%) or IV (62%) because of idiopathic dilated cardiomyopathy (59 patients) or ischemic, valvular, or familial cardiomyopathy (1 patient each). Outcomes considered for multivariable analysis included implantation of left ventricular assist device, return to class IV heart failure, relisting for transplantation, and death.

RESULTS

Partial left ventriculectomy reduced the left ventricular end-diastolic diameter immediately preoperatively to immediately postoperatively (from 8.4 +/- 1.1 cm to 5.92 +/- 0.8 cm; P =.01), reduced the left ventricular end-diastolic volume index (from 133 +/- 48.6 mL to 64.1 +/- 26 mL; P <.0001), and increased the left ventricular ejection fraction (from 16 +/- 7.6 to 31.5 +/- 10.9; P <.0001). Survival was 80% and 60% at 1 and 3 years after surgery and freedom from failure was 49% and 26%, respectively. Increased systolic pulmonary artery pressure, decreased maximum exercise oxygen consumption, and increased left atrial pressure were associated with failure and/or death. The degree of preoperative mitral regurgitation did not correlate with clinical outcome.

CONCLUSIONS

Early and late failures preclude the widespread use of partial left ventriculectomy. However, in view of its sometimes beneficial effect, use in situations that do not allow for transplantation or as a biologic bridge to transplantation may be appropriate.

Novel Device to Change Left Ventricular Shape for Heart Failure Treatment: Device Design and Implantation Procedure

The Myocor Myosplint is designed to decrease left ventricular (LV) wall stress by changing LV shape, thus improving contractile function in dilated hearts. This shape change is accomplished by surgically placing three Myosplints perpendicular to the LV long axis, drawing the LV walls inward, and creating a symmetric, bilobular LV. Specially designed instruments aid in the precise delivery of these devices. The purpose of this study was to test the safety and feasibility of the procedure in dogs. Dilated cardiomyopathy was induced in 40 healthy dogs (26.3+/-1.7 kg) by ventricular pacing at 230 beats per minute for an average of 25+/-4 days. Using epicardial echocardiography, we placed the Myosplints across the LV chamber, avoiding the major coronary arteries, papillary muscles, and mitral valve. Once placed, the Myosplints were used to draw the LV walls inward to a prescribed distance. In all cases, we successfully implanted three Myosplints without using cardiopulmonary bypass. There were no complications related to the device or procedure. Myosplint implantation to change LV shape is safe and repeatable on a beating cardiomyopathic canine heart. Further study of the procedure will be needed in humans.

Hypogammaglobulinemia following cardiac transplantation: a link between rejection and infection

BACKGROUND

Hypogammaglobulinemia (HGG) has been reported after solid organ transplantation and is noted to confer an increased risk of opportunistic infections.

OBJECTIVES

In this study, we sought to assess the relationship between severe HGG to infection and acute cellular rejection following heart transplantation.

METHODS

Between February 1997 and January 1999, we retrospectively analyzed the clinical outcome of 111 consecutive heart transplant recipients who had immunoglobulin G (IgG) level monitoring at 3 and 6 months post-transplant and when clinically indicated.

RESULTS

Eighty-one percent of patients were males, mean age 54 +/- 13 years, and the mean follow-up period was 13.8 +/- 5.7 months. Patients had normal IgG levels prior to transplant (mean 1137 +/- 353 mg/dl). Ten percent (11 of 111) of patients developed severe HGG (IgG < 350 mg/dl) post-transplant. The average time to the lowest IgG level was 196 +/- 125 days. Patients with severe HGG were at increased risk of opportunistic infections compared to patients with IgG > 350 mg/dl (55% [6 of 11] vs. 5% [5 of 100], odds ratio = 22.8, p < 0.001). Compared to patients with no rejection, patients who experienced three or more episodes of rejection had lower mean IgG (580 +/- 309 vs. 751 +/- 325, p = 0.05), and increased incidence of severe HGG (33% [7 of 21] vs. 2.8% [1 of 35], p = 0.001). The incidence of rejection episodes per patient at 1 year was higher in patients with severe HGG compared to patients with IgG >350 (2.82 +/- 1.66 vs. 1.36 +/- 1.45 episodes/patient, p = 0.02). The use of parenteral steroid pulse therapy was associated with an increased risk of severe HGG (odds ratio = 15.28, p < 0.001).

CONCLUSIONS

Severe HGG after cardiac transplantation may develop as a consequence of intensification of immunosuppressive therapy for rejection and hence, confers an increased risk of opportunistic infections. IgG level may be a useful marker for identifying patients at high risk.

Mitral inertance in humans: critical factor in Doppler estimation of transvalvular pressure gradients

The pressure-velocity relationship across the normal mitral valve is approximated by the Bernoulli equation DeltaP = 1/2 rhoDeltav(2) + M. dv/dt, where DeltaP is the atrioventricular pressure difference, rho is blood density, v is transmitral flow velocity, and M is mitral inertance. Although M is indispensable in assessing transvalvular pressure differences from transmitral flow, this term is poorly understood. We measured intraoperative high-fidelity left atrial and ventricular pressures and simultaneous transmitral flow velocities by using transesophageal echocardiography in 100 beats (8 patients). We computed mean mitral inertance (M) by M = integral((DeltaP)-(1/2 x rho v(2))dt/integral(dv/dt)dt and we assessed the effect of the inertial term on the transmitral pressure-flow relation. ranged from 1.03 to 5.96 g/cm(2) (mean = 3.82 +/- 1.22 g/cm(2)). DeltaP calculated from the simplified Bernoulli equation (DeltaP = 1/2. rhov(2)) lagged behind (44 +/- 11 ms) and underestimated the actual peak pressures (2.3 +/- 1.1 mmHg). correlated with left ventricular systolic pressure (r = -0.68, P < 0.0001) and transmitral pressure gradients (r = 0.65, P < 0.0001). Because mitral inertance causes the velocity to lag significantly behind the actual pressure gradient, it needs to be considered when assessing diastolic filling and the pressure difference across normal mitral valves.

Left ventricular assist device bridge to recovery: a review of the current status

The use of the left ventricular assist device as a bridge to recovery represents a new phenomenon. This article focuses on bridge-to-recovery in the settings of myocarditis and dilated cardiomyopathy with a review of the hemodynamic, neurohormonal, physiologic, cellular, and molecular changes of recovery during left ventricular assist device support. Despite numerous markers of success, there is a disconnect from the limited clinical successes that are reviewed. The current status and future options to increase the chances of success are highlighted.

Regional heterogeneity of function in nonischemic dilated cardiomyopathy

OBJECTIVE

To quantify regional three-dimensional (3D) motion and myocardial strain using magnetic resonance (MR) tissue tagging in patients with non-ischemic dilated cardiomyopathy (DCM).

METHODS

MR grid tagged images were obtained in multiple short- and long-axis planes in thirteen DCM patients. Regional 3D displacements and strains were calculated with the aid of a finite element model. Five of the patients were also imaged after LV volume reduction by partial left ventriculectomy (PLV), combined with mitral and tricuspid valve repair.

RESULTS

DCM patients showed consistent, marked regional heterogeneity. Systolic lengthening occurred in the septum in both circumferential (%S(C) -5+/-7%) and longitudinal (%S(L) -2+/-5%) shortening components (negative values indicating lengthening). In contrast, the lateral wall showed relatively normal systolic shortening (%S(C) 12+/-6% and %S(L) 6+/-5%, P<0.001 lateral vs. septal walls). A geometric estimate of regional stress was correlated with shortening on a regional basis, but could not account for the differences in shortening between regions. In the five patients imaged post-PLV, septal function recovered (%S(C) 9+/-5%,%S(L) 6+/-5%, P<0.02 pre vs. post) with normalization of wall stress, whereas lateral wall shortening was reduced (%S(C) 7+/-6%,%S(L) 3+/-3%, P<0.02 pre vs. post) around the site of surgical resection.

CONCLUSIONS

A consistent pattern of regional heterogeneity of myocardial strain was seen in all patients. Reduced function may be related to increased wall stress, since recovery of septal function is possible after PLV. However, simple geometric stress determinants are not sufficient to explain the functional heterogeneity observed.

Relationship between systolic and diastolic function with improvements in forward stroke volume following reduction in mitral regurgitation

Efforts to improve mitral regurgitation (MR) are often performed in conjunction with coronary revascularization. However, the independent effects of a reduced MR area (MRa) are difficult to quantify. Using a previously developed cardiovascular model, ventricular contractility (elastance 1-8 mmHg/ml) and relaxation (tau: 40-150 msec) were independently adjusted for four grades of MR orifice areas (0.0 to 0.8 cm2). Improvements in forward stroke volume (fSV) were determined for the permutations of reduced MRa. For all conditions, LV end-diastolic pressure and volumes ranged from 7.3-24.2 mmHg and 64.8-174.3 ml, respectively. Overall, fSV ranged from 36.0-89.4 (mean: 64.2 +/- 12.8) ml, improved between 6.4 and 35.3% (mean: 15.6 +/- 8.1%), and was best predicted by (r=0.97, p<0.01) %delta(fSV)[correction of fVS]=34[MRa initial] - 46[MRa final] -0.5[elastance]. Reduced MRa, independent of relaxation and minimally influence by contractility, yield improved fSVs.

Noninvasive assessment of mitral inertness [correction of inertance]: clinical results with numerical model validation

Inertial forces (Mdv/dt) are a significant component of transmitral flow, but cannot be measured with Doppler echo. We validated a method of estimating Mdv/dt. Ten patients had a dual sensor transmitral (TM) catheter placed during cardiac surgery. Doppler and 2D echo was performed while acquiring LA and LV pressures. Mdv/dt was determined from the Bernoulli equation using Doppler velocities and TM gradients. Results were compared with numerical modeling. TM gradients (range: 1.04-14.24 mmHg) consisted of 74.0 +/- 11.0% inertial forcers (range: 0.6-12.9 mmHg). Multivariate analysis predicted Mdv/dt = -4.171(S/D (RATIO)) + 0.063(LAvolume-max) + 5. Using this equation, a strong relationship was obtained for the clinical dataset (y=0.98x - 0.045, r=0.90) and the results of numerical modeling (y=0.96x - 0.16, r=0.84). TM gradients are mainly inertial and, as validated by modeling, can be estimated with echocardiography.

Decreased SLIM1 expression and increased gelsolin expression in failing human hearts measured by high-density oligonucleotide arrays

BACKGROUND

Failing human hearts are characterized by altered cytoskeletal and myofibrillar organization, impaired signal transduction, abnormal protein turnover, and impaired energy metabolism. Thus, expression of multiple classes of genes is likely to be altered in human heart failure.

METHODS AND RESULTS

We used high-density oligonucleotide arrays to explore changes in expression of approximately 7000 genes in 2 nonfailing and 2 failing human hearts with diagnoses of end-stage ischemic and dilated cardiomyopathy, respectively. We report altered expression of (1) cytoskeletal and myofibrillar genes (striated muscle LIM protein-1 [SLIM1], myomesin, nonsarcomeric myosin regulatory light chain-2 [MLC(2)], and ss-actin); (2) genes responsible for degradation and disassembly of myocardial proteins (alpha(1)-antichymotrypsin, ubiquitin, and gelsolin); (3) genes involved in metabolism (ATP synthase alpha-subunit, succinate dehydrogenase flavoprotein [SDH Fp] subunit, aldose reductase, and TIM17 preprotein translocase); (4) genes responsible for protein synthesis (elongation factor-2 [EF-2], eukaryotic initiation factor-4AII, and transcription factor homologue-HBZ17); and (5) genes encoding stress proteins (alphaB-crystallin and mu-crystallin). In 5 additional failing hearts and 4 additional nonfailing controls, we then compared expression of proteins encoded by the differentially expressed genes, alphaB-crystallin, SLIM1, gelsolin, alpha(1)-antichymotrypsin, and ubiquitin. In each case, changes in protein expression were consistent with changes in transcript measured by microarray analysis. Gelsolin protein expression was also increased in cardiomyopathic hearts from tropomodulin-overexpressing (TOT) mice and rac1-expressing (racET) mice.

CONCLUSIONS

Altered expression of the genes identified in this study may contribute to development of the heart failure phenotype and/or represent compensatory mechanisms to sustain cardiac function in failing human hearts.

Results of partial left ventriculectomy for dilated cardiomyopathy: hemodynamic, clinical and echocardiographic observations

OBJECTIVES

The study was done to prospectively measure the echocardiographic, hemodynamic and clinical outcomes after partial left ventriculectomy (PLV).

BACKGROUND

Although PLV can improve symptoms of advanced heart failure, immediate postoperative echocardiographic findings remain abnormal.

METHODS

Fifty-nine patients with cardiomyopathy and advanced heart failure underwent PLV and concomitant mitral valve surgery between May 1996 and December 1997. Thirty-nine percent were on inotropic therapy. All were New York Heart Association (NYHA) functional class III or IV. Mechanical circulatory support (LVAD) and transplant were provided for rescue therapy when hemodynamic compromise occurred. Patients were followed for a mean of 405+/-168 days, and clinical, echocardiographic and hemodynamic measures were obtained preoperatively, immediately postoperatively, and at 3 and 12 months prospectively.

RESULTS

Comparing preoperative and 12-month postoperative values in event-free survivors, we found: NYHA functional class improved from 3.6 to 2.1, p < 0.0001; peak oxygen consumption increased from 10.8 to 16.0 ml/kg/min, p < 0.0001; LV ejection fraction increased from 13+/-6.0% to 24+/-6.9%, p < 0.0001; LV end diastolic diameter decreased from 8.2+/-1.03 to 6.2+/-0.64 cm, p < 0.0001, and volume was reduced from 167+/-60 to 105+/-38 ml/m2, p = 0.02. Central hemodynamics did not normalize after surgery.

CONCLUSIONS

Partial left ventriculectomy can provide structural remodeling of the heart that may result in temporary improvement in clinical compensation. However, perioperative failures and the return of heart failure limit the propriety of this procedure.

Noninvasive estimation of transmitral pressure drop across the normal mitral valve in humans: importance of convective and inertial forces during left ventricular filling

OBJECTIVES

We hypothesized that color M-mode (CMM) images could be used to solve the Euler equation, yielding regional pressure gradients along the scanline, which could then be integrated to yield the unsteady Bernoulli equation and estimate noninvasively both the convective and inertial components of the transmitral pressure difference.

BACKGROUND

Pulsed and continuous wave Doppler velocity measurements are routinely used clinically to assess severity of stenotic and regurgitant valves. However, only the convective component of the pressure gradient is measured, thereby neglecting the contribution of inertial forces, which may be significant, particularly for nonstenotic valves. Color M-mode provides a spatiotemporal representation of flow across the mitral valve.

METHODS

In eight patients undergoing coronary artery bypass grafting, high-fidelity left atrial and ventricular pressure measurements were obtained synchronously with transmitral CMM digital recordings. The instantaneous diastolic transmitral pressure difference was computed from the M-mode spatiotemporal velocity distribution using the unsteady flow form of the Bernoulli equation and was compared to the catheter measurements.

RESULTS

From 56 beats in 16 hemodynamic stages, inclusion of the inertial term ([deltapI]max = 1.78+/-1.30 mm Hg) in the noninvasive pressure difference calculation significantly increased the temporal correlation with catheter-based measurement (r = 0.35+/-0.24 vs. 0.81+/-0.15, p< 0.0001). It also allowed an accurate approximation of the peak pressure difference ([deltapc+I]max = 0.95 [delta(p)cathh]max + 0.24, r = 0.96, p<0.001, error = 0.08+/-0.54 mm Hg).

CONCLUSIONS

Inertial forces are significant components of the maximal pressure drop across the normal mitral valve. These can be accurately estimated noninvasively using CMM recordings of transmitral flow, which should improve the understanding of diastolic filling and function of the heart.

Real-time three-dimensional echocardiographic study of left ventricular function after infarct exclusion surgery for ischemic cardiomyopathy

BACKGROUND

Infarct exclusion (IE) surgery, a technique of left ventricular (LV) reconstruction for dyskinetic or akinetic LV segments in patients with ischemic cardiomyopathy, requires accurate volume quantification to determine the impact of surgery due to complicated geometric changes.

METHODS AND RESULTS

Thirty patients who underwent IE (mean age 61+/-8 years, 73% men) had epicardial real-time 3-dimensional echocardiographic (RT3DE) studies performed before and after IE. RT3DE follow-up was performed transthoracically 42+/-67 days after surgery in 22 patients. Repeated measures ANOVA was used to compare the values before and after IE surgery and at follow-up. Significant decreases in LV end-diastolic (EDVI) and end-systolic (ESVI) volume indices were apparent immediately after IE and in follow-up (EDVI 99+/-40, 67+/-26, and 71+/-31 mL/m(2), respectively; ESVI 72+/-37, 40+/-21, and 42+/-22 mL/m(2), respectively; P:<0.05). LV ejection fraction increased significantly and remained higher (0.29+/-0.11, 0.43+/-0.13, and 0.42+/-0.09, respectively, P:<0.05). Forward stroke volume in 16 patients with preoperative mitral regurgitation significantly improved after IE and in follow-up (22+/-12, 53+/-24, and 58+/-21 mL, respectively, P:<0.005). New York Heart Association functional class at an average 285+/-144 days of clinical follow-up significantly improved from 3.0+/-0.8 to 1.8+/-0.8 (P:<0.0001). Smaller end-diastolic and end-systolic volumes measured with RT3DE immediately after IE were closely related to improvement in New York Heart Association functional class at clinical follow-up (Spearman's rho=0.58 and 0.60, respectively).

CONCLUSIONS

RT3DE can be used to quantitatively assess changes in LV volume and function after complicated LV reconstruction. Decreased LV volume and increased ejection fraction imply a reduction in LV wall stress after IE surgery and are predictive of symptomatic improvement.

Cardiac exercise hemodynamics late after partial left ventriculectomy

BACKGROUND

Although some patients report favorable activity levels late after partial left ventriculectomy (PLV), their exercise physiology has not been well described.

METHODS AND RESULTS

We performed upright bicycle hemodynamics in 10 patients (9 men) aged 56+/-12 years at 1.7 years after PLV. Ejection fraction was 25+/-4%. Patients biked 10+/-7 minutes. With exercise, the mean pulmonary arterial pressure rose from 36+/-12 to 52+/-10 mm Hg (P:=0.0003). The mean pulmonary capillary wedge pressure rose from 25+/-14 to 36+/-9 mm Hg (P:=0.0566), and the cardiac index rose from 2.2+/-0.5 to 3.8+/-1.6 L. min(-1). m(-2) (P:=0.0077). The mixed venous oxygenation with exercise declined from 44+/-9% to 24+/-17% (P:=0. 0220), and the pulmonary vascular resistance increased from 2.0+/-0. 9 to 2.3+/-1.1 Wood units (P:=0.5566).

CONCLUSIONS

In late follow-up after PLV with exercise, the cardiac index is significantly augmented. However, there are further rises in pulmonary artery and pulmonary capillary wedge pressures, suggesting abnormal compliance, with marked decline in mixed venous oxygenation. Elucidating late physiology after PLV may help pave the way for future innovative heart failure surgeries.

The atherosclerotic aorta at aortic valve replacement: surgical strategies and results

BACKGROUND

Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta poses technical challenges. The purpose of this study was to examine operative strategies and results of aortic valve replacement in patients with a severely atherosclerotic ascending aorta that could not be safely crossclamped.

PATIENTS AND METHODS

From January 1990 to December 1998, 4983 patients had aortic valve surgery; of these, 62 (1.2%) patients had a severely atherosclerotic ascending aorta and required hypothermic circulatory arrest to facilitate aortic valve replacement. They form the study group.

RESULTS

All patients had hypothermic circulatory arrest, but several different strategies were used to manage the ascending aorta. These techniques included aortic valve replacement with the use of hypothermic circulatory arrest (39%), ascending aortic endarterectomy (26%), ascending aortic replacement (19%), aortic inspection and crossclamping during hypothermic circulatory arrest (10%), and balloon occlusion of the ascending aorta (6%). Duration of hypothermic circulatory arrest was substantially longer for patients having aortic valve replacement with hypothermic circulatory arrest than for all other strategies. Hospital mortality was 14%, and 10% of patients had strokes. Increasing New York Heart Association functional class and impaired left ventricular function were risk factors for hospital mortality. Choice of operative technique did not influence patient outcome; however, no patient who underwent replacement of the ascending aorta had a stroke.

CONCLUSIONS

Aortic valve replacement in patients with severe atherosclerosis of the ascending aorta is associated with increased operative morbidity and mortality. Complete aortic valve replacement during hypothermic circulatory arrest, the "no-touch" technique, requires a prolonged period of circulatory arrest. Ascending aortic replacement is a preferred technique, as it requires a short period of hypothermic circulatory arrest and results in comparable mortality with a low risk of stroke.

Fluorescence spectroscopy of endomyocardial tissue post-human heart transplantation: does it correlate with histopathology?

BACKGROUND

A significant correlation between autofluorescence spectroscopy and heart allograft rejection has been described in the rat heterotropic allograft model. However, the use of this technique in human heart transplants has not been validate.

METHODS

We obtained fluorescence and reflectance spectra on 37 human endomyocardial biopsy specimens and correlated the spectra with International Society Heart and Lung Transplantation grade for histologic rejection.

RESULTS

Using different excitation wavelengths (ultraviolet, lambda = 337 nm; blue, lambda = 440 nm, and green, lambda = 486 nm), we found no significant difference in the fluorescence spectra among the different grades of rejection.

CONCLUSIONS

Fluorescence spectroscopy is not a sensitive method for detecting rejection in human heart transplant recipients.

Relationships between ability requirements and human errors in job tasks

This article describes a program of research investigating the relations between abilities required to perform job tasks and human error probabilities while performing these tasks. Study 1, using objectively derived human errors made in performing Air Force job tasks, evaluated an ability-requirements classification methodology and found that error rates were related to the numbers, types, and levels of different abilities required. In Study 2, subject matter expert panels used the methodology to identify the ability requirements of tasks in 2 different jobs found in each of 2 types of nuclear power plants. This study, using a task-anchored scale of human error probability, replicated the findings of Study 1, identified 2 ability requirements that cross-validated in predicting task-error probabilities across both jobs and plants, and identified other abilities specific to error probabilities in each job.

Implantable LVAD insertion in patients with previous heart surgery

Implantable LVAD insertion and support poses technical obstacles in patients with previous heart operations. In this study of 135 LVAD patients (64 pneumatic HeartMate; 39 vented-electric HeartMate; 32 Novacor devices), 72 (53%) had previous heart surgery. For patients with previous coronary artery bypass, the grafts were managed by replacement or preservation. For patients with ventricular aneursym (or aneursmysectomy), or partical left ventriculectomy, apical cannulation had to be modified to maintain precise unobstructed orientation of the inflow cannula towards the mitral valve. Mechanical mitral and aortic prostheses were rereplaced with tissue valves. Implantable cardioverter defibrillators were removed, or the LVAD pump was placed intraperitoneal and the generator was left in the abdominal wall pocket. There were no significant differences in reoperations for bleeding (22% primary vs 23% reoperations), perioperative RVAD support (12% primary vs 7% reoperation) or survival to transplant (82% primary vs 72% reoperations). In conclusion adjustment of standard LVAD implant technique can successfully manage most problems posed by patients with previous heart surgery.

Clinical utility of echocardiography in the management of implantable ventricular assist devices

BACKGROUND

The high mortality rate of congestive cardiac failure, the cost and complications of cardiac transplantation, and the waiting list mortality rate resulting from donor organ scarcity have encouraged the development of surgical techniques as bridges to transplantation or as long-term palliative therapy. Implantable left ventricular assist devices are now routinely used as such a bridge, and within the REMATCH Trial, as permanent palliative devices in nontransplant candidates. These are mechanical managements with myriad mechanical complications and pitfalls. Echocardiography has been extensively used in our institution to detect and diagnose previously documented and hitherto unencountered complications of these procedures.

METHODS AND RESULTS

The role of echocardiography in these procedures, including preoperative patient selection, intraoperative transesophageal echocardiography, and postoperative troubleshooting and late follow-up, is discussed. We describe our clinical echocardiographic approach, which has developed over 91 assist-device procedures. The relative frequency and clinical impact of specific anatomic, physiologic, hemodynamic, and mechanical features are described. New techniques such as the Doppler quantification of assist device inflow obstruction are illustrated, as are the device cannula position, the detection of device valve failure, and the parameters related to the remodeling procedure.

CONCLUSIONS

Echocardiography in heart failure surgery has proved to be an invaluable tool in the diagnosis and management of mechanical complications. The experience gained in our institution may serve as an aid to new surgical programs treating these critically ill patients.

Left ventricular reduction surgery with mitral valve repair

The echocardiographic changes and functional outcome from mitral valve repair, combined with partial left ventriculectomy (PLV), the Batista procedure, were investigated. From May 1996 to August 1997 the operation was performed on 57 patients, primarily (95%) transplant candidates with idiopathic dilated cardiomyopathy. All had been Class IV (36.8% had improved to Class III by the time of surgery) on medical therapy, including 40% hospitalized on inotropes and 3 patients on intra-aortic balloon pumps. The mean cardiac index was 2.1+/-0.6 L/min/m2, with a wedge pressure of 24+/-8 mm Hg, and norepinephrine levels of 855+/-500 pg/mL (normal 80-526 pg/mL). There were 2 in-hospital mortalities (3.5%). At 3 months there were significant persistent changes in LV end-diastolic diameter (8.1+/-1.0 cm-6.3+/-0.9 cm) and ejection fraction (13.6+/-6%-23+/-7.7%). Subjective improvement included a mean change in NYHA functional class from 3.7 to 2.2, and objective changes included improvement in peak oxygen consumption from 10.6+/-4 mL/kg/min to 15.4+/-4.5 mL/kg/min. Actuarial survival at 1 year was 82.1%; and freedom from death, relisting for transplantation, and need for LVAD support was 58%. The earliest "learning curve" experience with this relatively unstudied operation warrants careful investigation. Many questions remain to be answered, but many patients have demonstrated early subjective and objective improvement.

The impact of HLA sensitization and donor cause of death in heart transplantation

Current expansion of the recipient population and increased utilization of left ventricular assist devices as a bridge-to-transplantation have resulted in HLA sensitization becoming an increasingly important clinical problem in cardiac transplantation. We evaluated the impact of HLA sensitization and donor cause of death on survival in 500 cardiac transplant recipients. Donor cause of death was grouped into two categories, trauma and nontrauma. Panel reactive antibodies at the time of transplant were assayed and used as a marker for sensitization if more than 10%. Sensitized recipients had a poorer 1-year survival than those not sensitized (76 vs. 89%, respectively, P=0.2). Donor cause of death had an overall significant impact on survival with 1-year survival for recipients of trauma organs of 92 and 82% for recipients of nontrauma hearts (P=0.02). Trauma hearts transplanted into sensitized recipients yielded a survival of 93% at 1 year whereas if nontrauma donor hearts were transplanted into these recipients, survival was only 52% at 1 year, P<0.001. These intriguing results suggest that graft survival in HLA-sensitized recipients could be significantly improved through the use of hearts from trauma death donors.