Frank W. Smart

Right Ventricular Function and Failure Report of a National Heart, Lung, and Blood Institute Working Group on Cellular and Molecular Mechanisms of Right Heart Failure

Knowledge about the role of the right ventricle in health and disease historically has lagged behind that of the left ventricle. Less muscular, restricted in its role to pumping blood through a single organ, and less frequently or obviously involved than the left ventricle in diseases of epidemic proportions such as myocardial ischemia, cardiomyopathy, or valvulopathy, the right ventricle has generally been considered a mere bystander, a victim of pathological processes affecting the cardiovascular system. Consequently, comparatively little attention has been devoted to how right ventricular dysfunction may be best detected and measured, what specific molecular and cellular mechanisms contribute to maintenance or failure of normal right ventricular function, how right ventricular dysfunction evolves structurally and functionally, or what interventions might best preserve right ventricular function. Nevertheless, even the proportionately limited information related to right ventricular function, its impairment in various disease states, and its impact on the outcome of those diseases suggests that the right ventricle is an important contributor and that further understanding of these issues is of pivotal importance. For this reason, the National Heart, Lung, and Blood Institute convened a working group charged with delineating in broad terms the current base of scientific and medical understanding about the right ventricle and identifying avenues of investigation likely to meaningfully advance knowledge in a clinically useful direction. The following summary represents the presentations and discussions of this working group. The right ventricle is affected by and contributes to a number of disease processes, including perhaps most notably pulmonary hypertension caused by a variety of lung or pulmonary vascular diseases (cor pulmonale). Other diseases affect the right ventricle in different ways, including global, left ventricular–, or right ventricular–specific cardiomyopathy; right ventricular ischemia or infarction; pulmonary or tricuspid valvular heart disease; and left-to-right shunts. The right ventricle pumps the same …

A randomized active-controlled trial of mycophenolate mofetil in heart transplant recipients : Mycophenolate Mofetil Investigators

BACKGROUND After heart transplantation, 1-year and 5-year survival rates are 79% and 63%, respectively, with rejection, infection, and allograft coronary artery disease accounting for the majority of deaths. Mycophenolate mofetil (MMF), an inhibitor of the de novo pathway for purine biosynthesis, decreases rejection in animals and in human renal transplantation. METHODS In a double-blind, active-controlled trial, 28 centers randomized 650 patients undergoing their first heart transplant to receive MMF (3000 mg/day) or azathioprine (1.5-3 mg/kg/day), in addition to cyclosporine and corticosteroids. Rejection and survival data were obtained for 6 and 12 months, respectively. Because 11% of the patients withdrew before receiving study drug, data were analyzed on all randomized patients (enrolled patients) and on patients who received study medications (treated patients). RESULTS Survival and rejection were similar in enrolled patients (MMF, n=327; azathioprine, n=323). In treated patients (MMF, n=289; azathioprine, n=289), the MMF group compared with the azathioprine group was associated with significant reduction in mortality at 1 year (18 [6.2%] versus 33 deaths [11.4%]; P=0.031) and a significant reduction in the requirement for rejection treatment (65.7% versus 73.7%; P=0.026). There was a trend for fewer MMF patients to have > or = grade 3A rejection (45.0% versus 52.9%; P=0.055) or require the murine monoclonal anti-CD3 antibody or antithymocyte globulin (15.2% versus 21.1%; P=0.061). Opportunistic infections, mostly herpes simplex, were more common in the MMF group (53.3% versus 43.6%; P=0.025). CONCLUSIONS Substitution of MMF for azathioprine may reduce mortality and rejection in the first year after cardiac transplantation.

Transition From Chronic Compensated to Acute Decompensated Heart Failure Pathophysiological Insights Obtained From Continuous Monitoring of Intracardiac Pressures

Background— Approximately half of all patients with chronic heart failure (HF) have a decreased ejection fraction (EF) (systolic HF [SHF]); the other half have HF with a normal EF (diastolic HF [DHF]). However, the underlying pathophysiological differences between DHF and SHF patients are incompletely defined. The purpose of this study was to use echocardiographic and implantable hemodynamic monitor data to examine the pathophysiology of chronic compensated and acute decompensated HF in SHF versus DHF patients. Methods and Results— Patients were divided into 2 subgroups: 204 had EF <50% (SHF) and 70 had EF ≥50% (DHF). DHF patients had EF of 58±8%, end-diastolic dimension of 50±10 mm, estimated resting pulmonary artery diastolic pressure (ePAD) of 16±9 mm Hg, and diastolic distensibility index (ratio of ePAD to end-diastolic volume) of 0.11±0.06 mm Hg/mL. In contrast, SHF patients had EF of 24±10%, end-diastolic dimension of 68±11 mm, ePAD of 18±7 mm Hg, and diastolic distensibility index of 0.06±0.04 mm Hg/mL (P<0.05 versus DHF for all variables except ePAD). In SHF and DHF patients who developed acute decompensated HF, these events were associated with a significant increase in ePAD, from 17±7 to 22±7 mm Hg (P<0.05) in DHF and from 21±9 to 24±8 mm Hg (P<0.05) in SHF. As a group, patients who did not have acute decompensated HF events had no significant changes in ePAD. Conclusions— Significant structural and functional differences were found between patients with SHF and those with DHF; however, elevated diastolic pressures play a pivotal role in the underlying pathophysiology of chronic compensated and acute decompensated HF in both SHF and DHF.

Insensitivity of noninvasive tests to detect coronary artery vasculopathy after heart transplant

Obstructive coronary artery vasculopathy can be a major problem after cardiac transplant. The use of noninvasive tests to detect coronary artery vasculopathy was studied in 73 consecutive patients after heart transplant. Angiographically or autopsy-proved coronary artery disease was noted in 19 consecutive patients (26%) followed prospectively for 2.5 +/- 1.3 years (mean +/- standard deviation). Patients underwent yearly surveillance echocardiographic, rest/exercise-gated wall motion, oral dipyridamole thallium, ambulatory electrocardiographic monitor and angiographic studies. Positive test results were defined by decrease in ejection fraction, wall motion abnormality, failure to increase ejection fraction, lack of systolic blood pressure increase, and ischemic ST changes at maximal exercise (or on ambulatory monitor). Wall motion abnormalities and depressed ejection fraction on echocardiography were also abnormal studies as were fixed or reversible perfusion defects on thallium scan. Angiograms were considered positive when 50% luminal narrowing was observed and autopsy coronary artery vasculopathy was defined as cross-sectional coronary obstruction greater than or equal to 70%. No procedure that was examined proved to be a sensitive noninvasive detector of heart transplant coronary artery vasculopathy. All except ambulatory electrocardiographic monitoring had positive predictive values less than 50%. Interestingly, of the techniques evaluated, echocardiography was most sensitive (53%). The poor predictive ability of noninvasive testing in this population may be due to the fact that these tests are designed to detect effects of ischemia rather than coronary obstruction alone. Use of these particular noninvasive modalities routinely after heart transplant to detect coronary artery vasculopathy should be reconsidered because of their low sensitivity and predictive value when used as a surveillance screen.

Guidelines for the referral and management of patients eligible for solid organ transplantation.

Members of the Clinical Practice Committee, American Society of Transplantation, have attempted to define referral criteria for solid organ transplantation. Work done by the Clinical Practice Committee does not represent the official position of the American Society of Transplantation. Recipients for solid organ transplantation are growing in numbers, progressively outstripping the availability of organ donors. As there may be discrepancies in referral practice and, therefore, inequity may exist in terms of access to transplantation, there needs to be uniformity about who should be referred to transplant centers so the system is fair for all patients. A review of the literature that is both generic and organ specific has been conducted so referring physicians can understand the criteria that make the patient a suitable potential transplant candidate. The psychosocial milieu that needs to be addressed is part of the transplant evaluation. Early intervention and evaluation appear to play a positive role in maximizing quality of life for the transplant recipient. There is evidence, especially in nephrology, that the majority of patients with progressive failure are referred to transplant centers at a late stage of disease. Evidence-based medicine forms the basis for medical decision-making about accepting the patient as a transplant candidate. The exact criteria for each organ are detailed. These guidelines reflect consensus opinions, synthesized by the authors after extensive literature review and reflecting the experience at their major transplant centers. These guidelines can be distributed by transplant centers to referring physicians, to aid them in understanding who is potentially an acceptable candidate for transplantation. The more familiar physicians are with the exact criteria for specific organ transplantation, the more likely they are to refer patients at an appropriate stage. Individual transplant centers will make final decisions on acceptability for transplantation based on specific patient factors. It is hoped that this overview will assist insurers/payors in reimbursing transplant centers for solid organ transplantation, based on criteria for acceptability by the transplant community. The selection and management of patients with end-stage organ failure are constantly changing, and future advances may make obsolete some of the criteria mentioned in the guidelines. Most importantly, these are intended to be guidelines, not rules.

Cardiomyocyte Transplantation in a Porcine Myocardial Infarction Model

Transplantation of cardiomyocytes into the heart is a potential treatment for replacing damaged cardiac muscle. To investigate the feasibility and efficiency of this technique, either a cardiac-derived cell line (HL-1 cells), or normal fetal or neonatal pig cardiomyocytes were grafted into a porcine model of myocardial infarction. The myocardial infarction was created by the placement of an embolization coil in the distal portion of the left anterior descending artery in Yorkshire pigs (n = 9). Four to 5 wk after creation of an infarct, the three preparations of cardiomyocytes were grafted, at 1 x 10(6) cells/20 microL into normal and into the middle of the infarcted myocardium. The hearts were harvested and processed for histologic examinations 4 to 5 wk after the cell grafts. Histologic evaluation of the graft sites demonstrated that HL-1 cells and fetal pig cardiomyocytes formed stable grafts within the normal myocardium without any detrimental effect including arrhythmia. In addition, a marked increase in angiogenesis was observed both within the grafts and adjacent host myocardium. Electron microscopy studies demonstrated that fetal pig cardiomyocytes and the host myocardial cells were coupled with adherens-type junctions and gap junctions. Histologic examination of graft sites from infarct tissue failed to show the presence of grafted HL-1 cells, fetal, or neonatal pig cardiomyocytes. Cardiomyocyte transplantation may provide the potential means for cell-mediated gene therapy for introduction of therapeutic molecules into the heart.

Cardiac allograft vasculopathy: current concepts.

The major cause of late death in cardiac transplant recipients is cardiac allograft vasculopathy, also referred to as cardiac transplant atherosclerosis, which occurs in 15% to 20% of transplant recipients. It differs from traditional atherosclerosis in that it is a concentric and diffuse intimal hyperplastic process; the internal elastic lamina remains intact; calcification is rare; and the disease tends to develop rapidly. Although no definitive reason for cardiac allograft vasculopathy has been established, it has been suggested that it may be caused by a combination of immunologic and nonimmunologic damage to endothelial cells that results in myointimal proliferation. Intravascular ultrasound and coronary angioscopy are more sensitive diagnostic measures of cardiac allograft vasculopathy than coronary angiography. Although retransplantation currently seems to be the only definitive therapy for cardiac allograft vasculopathy, it has shown only fair results.

Predictive model to assess risk for cardiac allograft vasculopathy: an intravascular ultrasound study.

OBJECTIVES This study was performed to assess the influence and interdependence of immunologic and nonimmunologic risk factors in the development of cardiac allograft vasculopathy. Another primary objective was to establish a clinically useful model for risk assessment of cardiac allograft vasculopathy that would facilitate identifying those heart transplant recipients likely to have severe intimal proliferation and thereby at greater risk for adverse clinical events. BACKGROUND To our knowledge, no comprehensive intravascular ultrasound study has assessed the relative influences of both nonimmunologic and immunologic factors in the development of cardiac allograft vasculopathy, currently the major limitation to long-term cardiac allograft survival. METHODS Using a computer-assisted model of stepwise logistic regression, immunologic and nonimmunologic risk factors were evaluated to help identify the development of severe intimal thickening in 101 subjects who underwent intravascular ultrasound. Prospective validation of the findings was performed in a separate consecutive cohort of 37 heart transplant recipients, and the accuracy of this model to predict a relative risk > 1 for the development of severe intimal hyperplasia was assessed. RESULTS Significant independent predictors of severe intimal hyperplasia in this model included a donor age > 35 years, a first-year mean biopsy score > 1 (a measure not only of severity of rejection, but also of frequency of insidious rejection) and hypertriglyceridemia at two incremental levels of risk (150 to 250 mg/dl [1.70 to 2.83 mmol/liter] and > 250 mg/dl [2.83 mmol/liter]). Based on the absence (0) or presence (1) of these factors, 12 individual categories of risk were ascertained with increasing relative risks and predicted probabilities for severe intimal hyperplasia. Prospective validation of this model revealed a sensitivity and specificity of 70% and 90%, respectively, and the positive and negative predictive values were 85% and 80%, respectively. Additionally, subjects with severe intimal thickening had a four-fold higher cardiac event rate than those without severe intimal proliferation on intravascular ultrasound. CONCLUSIONS This study establishes a clinically useful predictive model that can be applied to individual heart transplant recipients to assess their risk for developing significant cardiac allograft vasculopathy and, thus, aids in the identification of patients at risk for cardiac events in whom closer surveillance and risk factor modification may be warranted.

An intravascular ultrasound study of the influence of angiotensin-converting enzyme inhibitors and calcium entry blockers on the development of cardiac allograft vasculopathy.

In conclusion, this intravascular ultrasound study suggests that treatment of cardiac transplant recipients with either ACE inhibitors or CEBs is associated with a decrease in the degree of vascular intimal hyperplasia at 1 year after transplantation. Thus, early intervention with CEBs or ACE inhibitors offers a preventive option for the devastating consequences of cardiac allograft vasculopathy.

Cardiac allograft vasculopathy assessed by intravascular ultrasonography and nonimmunologic risk factors

The genesis of cardiac allograft vasculopathy has been linked to nonimmunologic endothelial injury. Studies evaluating the role of nonimmunologic risk factors have thus far been limited to angiographic assessment. Intravascular ultrasound can detect cardiac allograft vasculopathy before it becomes angiographically evident. To assess the influence of nonimmunologic risk factors in the development of cardiac allograft vasculopathy, we studied 101 consecutive cardiac transplant recipients who underwent intracoronary ultrasound imaging during routine, annual coronary angiography. Based on the severity of intimal thickening, patients were divided into 2 groups: group 1 = minimal, mild, or moderate intimal thickness; and group 2 = severe intimal thickness. Cardiac transplant recipients with severe intimal thickness had higher levels of total cholesterol (267 +/- 70 vs 227 +/- 41 mg/dl, p = 0.0008), low-density lipoprotein cholesterol (187 +/- 47 vs 139 +/- 31 mg/dl, p = 0.0001), and triglycerides (237 +/- 75 vs 182 +/- 88 mg/dl, p = 0.0004), a higher percentage of weight gain (12 +/- 4% vs 8 +/- 5%, p = 0.0001), a larger body mass index (30 +/- 4 vs 25 +/- 3, p = 0.0001), and older donor age (27 +/- 5 vs 23 +/- 7 years, p = 0.005) than recipients with mild or moderate intimal thickness. Multiple regression analysis established that total cholesterol, low-density lipoprotein cholesterol, triglyceride levels, obesity indexes, donor age, and years following cardiac transplantation (p < 0.01) were independent predictors of the severity of intimal thickening, and thus the severity of cardiac allograft vasculopathy.(ABSTRACT TRUNCATED AT 250 WORDS)