Dopamine treatment of locally procured donor hearts: relevance on postoperative cardiac histology and function

Cardiac donor management: another point of view

The shortage of suitable donor hearts is an important limiting factor in heart transplantation and continues to produce discussion about adequate donor management with regard to graft quality. Recent recommendations, such as limiting the doses of catecholamines for maintenance therapy of cardiac donors, have causes up to two thirds of cardiovascular surgeons to refuse a heart graft from a donor treated with dopamine doses greater than 10 microg/kg/min although endogenous catecholamines may cardiac and pulmonary complications in organ donors, these conditions may be treated using similar agents. Perhaps it is the magnitude of the endogenous catecholamine surge that produces the pathology; thereafter, the levels, may quickly decrease to the point of catecholamine depletion at the receptor level so that exogenous administration is not deleterious and even can have beneficial effects. In the hemodynamic management of organ donors, administration of catecholamines with alpha and beta-1 effects may be needed in sufficient doses to reverse the loss of sympathetic tone at the vascular and cardiac level. Hemodynamic responses display a great individual variability; therefore, a maximal dose should not be set. Catecholamine administration increases coronary artery perfusion pressure, thus optimizing the cardiac performance. Furthermore, it is possible that immunomodulatory effects of catecholamines influence acute allograft rejection rates.

Relationships between hemodynamic parameters and myocardial energy and antioxidant status in heart transplantation

The relationships between high-energy phosphate levels, oxidative insult and mechanical function represent a key point in heart transplantation and related post-ischemic functional recovery. We evaluated myocardial purine compounds and glutathione antioxidant defence mechanism during 19 heart transplant operations. Heart biopsies were taken before harvesting on beating heart (t1), at the end of cold static preservation (t2) and 30 min after implantation and reperfusion (t3); perchloric extracts of the tissue were analyzed by capillary electrophoresis (CE). Correlation analyses were performed with hemodynamic parameters evaluated 90 min after aortic declamping (T90), 6 h following admission in intensive care unit (T6A) and 1 d post-operation (D1). We evidenced that AMP levels measured at T1 negatively correlate with both cardiac index (CI) and oxygen delivery index (DO2I) evaluated at T6A, respectively. The same behavior was evident plotting IMP levels measured at T3 with CI and DO2I evaluated at D1. After t2 the nucleotide/(nucleoside + base) ratio was in positive correlation with hemodynamic parameters at T6A. Energy charge and GSH/GSSG ratio measured before harvesting were in positive correlation with DO2I evaluated at T90. The present research shows that despite the complexity of the high-energy phosphate metabolism and that of the events associated to a clinical heart transplantation, there are some parameters that, besides reflecting the degree of myocardial preservation, also represents predictive parameters for the following organ functional recovery. It also suggests that heart preservation strategies should carefully take into account the sub-optimal nature of the donor heart at the time of procurement, through a broad spectrum of purine compound and glutathione antioxidant system measurements.

Bio-energetic response of the heart to dopamine following brain death-related reduced myocardial workload: a phosphorus-31 magnetic resonance spectroscopy study in the cat

OBJECTIVE

Long-term exposure of the donor heart to high dosages of dopamine in the treatment of brain death-related hemodynamic deterioration has been shown to reduce myocardial phosphocreatine (PCr) and adenosine triphosphate (ATP) in myocardial biopsy specimens and may preclude heart donation for transplantation. Short-term exposure to the acute catecholamine release during the onset of brain death has shown an unchanged PCr/ATP ratio using in vivo phosphorus-31 magnetic resonance spectroscopy (31P MRS). In this study 31P MRS was used to evaluate in vivo myocardial energy metabolism during long-term dopamine treatment.

METHODS

Twelve cats were studied in a 4.7 Tesla magnet for 360 minutes. At t = 0 minutes, brain death was induced (n = 6). At 210 minutes, when myocardial workload in the brain-death group was reduced significantly, dopamine was infused (n = 12) at 5 microg/kg/min and its dose was consecutively doubled every 30 minutes and was withheld during the last 30 minutes of the experiment. Phosphorus-31 magnetic resonance spectra were obtained from the left ventricular wall during 5-minute time frames, and PCr/ATP ratios were calculated. The hearts were histologically examined.

RESULTS

Although significant changes in myocardial workload were observed after the induction of brain death and during support and withdrawal of dopamine in both groups, the initial PCr/ATP ratio of 2.00+/-0.12 and the contents of PCr and ATP did not vary significantly. Histologically identified sub-endocardial hemorrhage was observed in 3 of 6 of the brain-dead animals and in 1 of 6 of the control animals.

CONCLUSIONS

High dosages of dopamine in the treatment of brain death-related reduced myocardial workload do not alter PCr/ATP ratios and the contents of PCr and ATP of the potential donor heart despite histologic damage.

Heart transplantation-associated perioperative ischemic myocardial injury. Morphological features and clinical significance

BACKGROUND

The frequency and clinical significance of perioperative ischemic myocardial injury (PIMI) after heart transplantation and the diagnostic features distinguishing PIMI from rejection are not well defined.

METHODS AND RESULTS

We evaluated PIMI in the first four weekly endomyocardial biopsies and/or autopsy myocardium from 140 consecutive orthotopic heart transplantation recipients (1984 to 1991) by grading the severity of coagulative myocyte necrosis (CMN) as absent, 0; mild-focal, 1; moderate-multifocal, 2; or severe-confluent, 3, and determining the evolution of morphological features of its healing. CMN (often with contraction bands) was noted in 124 patients (89%); 24 patients (17%) had grade 3 CMN, of which 4 died within 30 days of transplantation. Nevertheless, at 1 year after surgery, survival was similar in patients with and without severe injury. Increased cold ischemic time but neither donor age nor intensity of inotropic support correlated with more severe early ischemic injury. PIMI inflammation was characterized by a predominantly polymorphonuclear/histiocytic infiltrate that contained lymphocytes and plasma cells, expanding the interstitium but not encroaching upon and separable from adjacent viable myocytes. Histological features of PIMI developed and resolved more slowly than those of typical myocardial infarct necrosis in nonimmunosuppressed patients; at 4 weeks, CMN persisted in 20% of patients and residual healing in nearly half. Diagnostic rejection was observed concurrently with PIMI in 54 of 533 biopsies (10%).

CONCLUSIONS

Diagnosed by conventional histological criteria, PIMI is prevalent early after heart transplantation and has a protracted healing phase that can mimic or coexist with rejection. Extensive PIMI has deleterious impact on short-term survival, but the long-term impact of PIMI remains to be established.

Early cardiac allograft failure after orthotopic heart transplantation

Early cardiac graft failure has been reported to occur in 4-25% of patients undergoing orthotopic heart transplantation. To further elucidate the characteristics and prognosis of patients with graft failure, we retrospectively identified 10 patients from a series of 212 consecutive recipients with catastrophic graft dysfunction in the absence of acute cellular rejection, right ventricular failure secondary to pulmonary hypertension and technical factors. We present a case report and the experience from one transplant center, a review of the literature and possible strategies for the management of early graft failure. Mean onset of graft failure was 6.5 days (range intraoperative to 23 days). Multivariable analysis revealed a longer total ischemic time in patients with early graft dysfunction (200 +/- 14 vs. 166 +/- 4 min). No episodes of hyperacute rejection were observed. Pathologic changes noted on biopsy or autopsy included ischemia in 9 and vascular rejection in 1. The mortality at 60 days was 50%. Early use of aggressive mechanical and pharmacological support is described and appears to be important for graft salvage.

Cardiac allografts from high-risk donors: excellent clinical results

Rising waiting list mortality and increasing demand for donor organs have led to extension of traditionally accepted criteria for evaluation of cardiac grafts. From December 1985 to June 1992, 188 cardiac grafts were orthotopically transplanted into 178 recipients. Of these grafts, 38.3% (72/188) were defined as high-risk donors. Risk criteria included prolonged cardiopulmonary resuscitation, age greater than 40 years, high inotrope requirements, undersizing by more than 20% body weight, significant wall motion impairment by echocardiography, elevation of myocardial enzyme levels, and cold ischemia time greater than 4 hours. There were no recipient deaths attributable to primary graft failure in the perioperative period. Operative (30-day), 1-year and 5-year survival was 95.5%, 86.1%, and 77.3%, respectively, in the high-risk group compared with 93.7%, 86.0%, and 67.2%, respectively, in the low-risk donor cohort (p = 0.94). Comparison of duration of postoperative inotrope use, intensive care unit stay, total hospital stay, and in-hospital costs revealed no significant trends favoring either group in postoperative morbidity. Among long-term survivors, development of graft coronary disease was noted in 47.1% (24/51) of the high-risk donor group and only 17.4% (12/69) of the remaining group (p = 0.0005). Left ventricular ejection fractions in the high risk donor group were 0.58 +/- 0.01 at 2 years. Review of this series suggests that selective use of apparently compromised cardiac donors is compatible with excellent cardiac function and survival. Higher incidence of graft vasculopathy may cause significant morbidity during late follow-up.

Donor treatment after pronouncement of brain death: a neglected intensive care problem

The need for cadaveric organs for transplantation is increasing. To decrease the shortage of organs, identification of potential donors and conditioning of these donors must improve. We present a review of relevant data on body and tissue alterations due to brain death and summarize the recent literature covering experimental and clinical studies on optimal donor management.

Contractility of the transplanted, denervated human heart

The purpose of the study was to characterize the contractility of the transplanted human heart and to evaluate possible adverse effects of denervation or structural changes of the myocardium or coronary vessels. As an index of contractility, the linear slope k of the end-systolic pressure/dimension relationship during afterload increase with angiotensin II was determined by M-mode echocardiography in 34 heart transplant recipients and 20 healthy control subjects. Baseline findings for end-systolic diameter and systolic blood pressure were normal and similar in both groups, but the transplanted hearts performed at a significantly lower end-systolic wall stress (40.4 +/- 12 gm/cm2 vs 49.9 +/- 11 gm/cm2, p less than 0.001). Comparable increase of afterload was achieved in heart transplant recipients with significantly (p less than 0.001) less angiotensin II, which indicates increased vasoconstrictor sensitivity. Contractility index k did not differ between heart transplant recipients (12.95 +/- 4.9 mm/100 mm Hg) and control subjects (12.78 +/- 2.8 mm/100 mm Hg). This finding is consistent with a normal contractility of the transplanted, denervated human heart. Normal baseline contractility therefore is an intrinsic property of the intact heart, which is independent of autonomic neural control. Contractility was not compromised by increasing interval from transplantation or the presence of mild acute rejection or mild interstitial fibrosis. Mildly impaired contractility (k greater than 2 SD of k in control subjects) in four heart transplant recipients (12%) was neither associated with structural myocardial or coronary changes nor with rejection episodes or graft ischemic time. One may speculate that impaired contractility, which is present in a minority of heart transplant recipients, results from pretransplantation damage.