Long-term benefit of thrombolytic therapy in patients with pulmonary embolism.

A total of 23 of the 40 patients who had angiographically proven pulmonary embolism and who had initially been randomized to an IV infusion of heparin (n = 11) or a thrombolytic agent (urokinase or streptokinase, n = 12) were restudied after a mean follow-up of 7.4 years to measure the right-sided pressures and to evaluate their response to exercise during supine bicycle ergometry. Results showed that, at rest, the pulmonary artery (PA) mean pressure and the pulmonary vascular resistance (PVR) were significantly higher in the heparin group compared with the thrombolytic group (22 vs. 17 mmHg, p<0.05, and 351 vs. 171 dynes s(-1) cm(-5), p<0.02, respectively). During exercise both parameters rose to a significantly higher level in the heparin group (from rest to exercise, PA: 22-32 mmHg, p<0.01; PVR: 351-437 dynes s(-1) cm 5, p<0.01, respectively), but not in the thrombolytic group (rest to exercise, PA: 17-19 mm Hg, p = NS; PVR: 171-179 dynes s(-1) cm(-5), p = NS). It is concluded that thrombolytic therapy preserves the normal hemodynamic response to exercise in the long term and may prevent recurrences of venous thromboembolism and the development of pulmonary hypertension.

Management of atrial fibrillation: out-of-hospital approach.

Atrial fibrillation is increasingly common with advancing age and is responsible for 10% of the half-million strokes that occur annually in the United States. When a patient presents with atrial fibrillation, the physician's first task is to use the history, physical examination, and electrocardiogram to determine whether hospitalization is necessary. Factors indicating a need for hospital care include evidence of infarction or ischemia, congestive heart failure, hypotension or hypoperfusion, excessive rate, or pre-excitation. In addition, if the episode began within 48 hours, consider early cardioversion, which also requires hospitalization. Next, the need for control of the ventricular rate should be assessed. A heart rate under 90 beats/min at rest and under 120 beats/min after 1 minute of step exercise is a reasonable goal. Dixogin usually controls the resting rate, but sometimes beta-blockers or calcium channel blockers are needed to control the exercise rate. The need for anticoagulation is determined by the presence of clinical risk factors such as valvular heart disease, previous thromboembolism, hypertension, age over 65 years, congestive heart failure, and left atrial enlargement. An echocardiogram is necessary to complete this assessment. Patients having one or more of these risk factors are most effectively treated with warfarin, as evident from several clinical trials. Although patients over age 65 demonstrate reduced thromboembolism with warfarin therapy, they also are more prone to cerebral hemorrhage, thus, their international normalization ratio (INR) should be kept at the lower end of the therapeutic range [2,3]. Other patients can be treated with aspirin, although stroke reduction in these patients may be more related to reduction of arterial thrombosis than thromboembolism. Patients under age 65 with no risk factors have a very low annual risk of stroke without therapy (approximately 1%). If symptoms persist or if this is a first episode in someone without left atrial enlargement, cardioversion can be considered after 3 weeks of warfarin therapy with INR in the therapeutic range. Otherwise, warfarin should be continued indefinitely. Prevention of recurrence with antiarrhythmic drugs is somewhat problematic because of incomplete efficacy (30% recurrence at 1 year) and the potential for inducing other, life-threatening arrhythmias.

Two- to three-year follow-up of patients with single-vessel coronary artery disease randomized to PTCA or medical therapy (results of a VA cooperative study). Veterans Affairs Cooperative Studies Program ACME Investigators. Angioplasty Compared to Medicine.

Despite increasing use of percutaneous transluminal coronary angioplasty (PTCA) to treat stenotic coronary artery disease, there are relatively few prospective studies evaluating its long-term effectiveness. We prospectively randomized 212 stable patients with provocable myocardial ischemia and single-vessel subocclusive coronary disease to receive primary therapy with either PTCA or medical therapy. This report presents the clinical follow-up of these patients at a mean, after randomization, of 2.4 years for interview and 3.0 years for exercise testing. Of the 212 patients originally randomized, 175 received an extended follow-up interview, and 132 underwent exercise testing; 62% of patients in the PTCA group were angina free compared with 47% of patients in the medical group (p <0.05). Furthermore, exercise duration as measured by treadmill testing was prolonged by 1.33 minutes over baseline in the PTCA group, whereas it decreased by 0.28 minutes in the medical group (p <0.04). Although the angina-free time on the treadmill was not different (p=0.50), fewer patients in the medical group developed angina on the treadmill at 3 years than those in the PTCA group (p=0.04). By 36 months, excluding the initial randomized PTCA, use of PTCA and use of coronary artery bypass surgery were not different in the 2 treatment groups. These data indicate that some of the early benefits derived from PTCA in patients with single-vessel coronary artery disease are sustained, making it an attractive therapeutic option for these patients.

Evaluation of exercise thallium scintigraphy versus exercise electrocardiography in predicting survival outcomes and morbid cardiac events in patients with single- and double-vessel disease. Findings from the Angioplasty Compared to Medicine (ACME) Study.

OBJECTIVES: We sought to evaluate the prognostic ability of cardiac exercise stress tests in predicting cardiac mortality and morbidity in a low risk group of patients with established coronary artery disease (CAD). BACKGROUND: Although previous studies have demonstrated the superior value of stress nuclear cardiac scintigraphy in the prognosis of patients with CAD, none of these studies have focused on patients with a proven angiographic low risk profile (i.e., single- and double-vessel CAD). METHODS: Three hundred twenty-eight patients with documented single- and double-vessel disease were treated by random assignment to percutaneous transluminal coronary angioplasty or medical therapy in the Angioplasty Compared to Medicine (ACME) trial. Six months after randomization, maximal symptom-limited exercise tests were performed with electrocardiography (n = 300) and thallium scintigraphy (n = 270). Patients were followed up for a minimum of 5 years thereafter. RESULTS: A reversible thallium perfusion deficit documented after 6 months of either therapy was associated with an adverse mortality outcome (18% mortality rate with a reversible thallium perfusion defect and 8% mortality rate with no reversible thallium perfusion deficit, p = 0.02). Moreover, an important mortality gradient was demonstrated in relation to the number of reperfusing defects (0 = 7%, 1 to 2 = 15%, >3 = 20%, p = 0.04). Exercise electrocardiography did not predict this mortality outcome. CONCLUSIONS: A reversible thallium perfusion deficit demonstrated 6 months after medical therapy or coronary angioplasty is a valuable prognostic marker in patients with angiographically documented single- and double-vessel disease and is superior to exercise electrocardiography in this regard.

Percutaneous transluminal coronary angioplasty versus medical therapy for stable angina pectoris: outcomes for patients with double-vessel versus single-vessel coronary artery disease in a Veterans Affairs Cooperative randomized trial. Veterans Affairs ACME InvestigatorS.

OBJECTIVES: This study sought to assess outcomes of men with double-vessel coronary artery disease randomly assigned to treatment by percutaneous transluminal coronary angioplasty (PTCA) or medical therapy, compared with previously reported outcomes for men with single-vessel disease. BACKGROUND: We previously reported that PTCA provides better symptom relief and treadmill performance than medical therapy for men with stable angina pectoris due to single-vessel disease. Whether this advantage applies to patients with double-vessel disease is unknown. METHODS: Male patients (n = 328) with stable angina pectoris and ischemia on treadmill testing were randomly assigned to PTCA or medical therapy; 101 patients had double-vessel disease, and 227 had single-vessel disease. Symptoms, treadmill performance, quality of life score, coronary stenosis and myocardial perfusion were compared at baseline and at 6 months. Patients were followed up for up to 6 years and underwent additional treadmill testing 2 to 3 years after randomization. RESULTS: PTCA-treated and medically treated patients with double-vessel disease experienced comparable improvement in exercise duration (+1.2 vs. +1.3 min, respectively, p = 0.89), freedom from angina (53% and 36%, respectively, p = 0.09) and improvement of overall quality of life score (+1.3 vs. +4.4, respectively, p = 0.32) at 6 months compared with baseline. This contrasts with greater advantages favoring PTCA by these criteria in patients with single-vessel disease (p = 0.0001 to 0.02). Trends present at 6 months persisted at late follow-up. Patients undergoing double-vessel dilation had less complete initial revascularization (45% vs. 83%) and greater average stenosis of worst lesions at 6 months (74% vs. 56%). Likewise, patients with double-vessel disease showed less improved myocardial perfusion imaging (59% vs. 75%). CONCLUSIONS: PTCA is beneficial in male patients with double-vessel disease; however, we cannot demonstrate the same advantage over medical therapy seen in similar patients with single-vessel disease. Less complete revascularization and greater restenosis for patients having multiple dilations would account for these findings. Alternatively, a type 2 error might be operative. Technical advances since completion of this trial might improve these outcomes. These findings warrant further investigation in a larger trial.

Is computer interpretation of the exercise electrocardiogram a reasonable surrogate for visual reading? Veterans Affairs ACME Investigators.

BACKGROUND: Interpretation of exercise tests as positive or negative is primarily based upon exercise-induced ST segment changes. Consistently accurate measurements are difficult to obtain during exercise. HYPOTHESIS: This study compared on-line computer-generated electrocardiographic (ECG) analysis with visual interpretation. The goals were to document the extent of agreement, establish reasons for disagreements, characterize ST-segment depression (extent, onset, duration), and determine the sensitivity and ability to localize coronary artery disease for each method. METHODS: Comparisons were made in 120 patients at eight Veterans Affairs Medical Centers. An exercise test was considered positive if > 1.0 mm horizontal or downsloping ST-segment depression was detected 0.08 s after the J point during exercise or recovery. The ST-segment depression had to be present on at least two successive ECG recordings 15 s apart. Computer interpretation was based on median averaged beats. RESULTS: There was an 88% agreement of visual and computer interpretations [106/120 (both positive, n = 62; both negative, n = 44)]. The disagreements involved visual negative, computer positive in 10 cases and visual positive, computer negative in 4 cases. Correlation was excellent between methods for characterization of ST-segment depression (p < 0.0001). Sensitivity for detecting and the ability to localize coronary artery disease (> or = 70% stenosis) were similar for both methods. CONCLUSION: This computer algorithm using median averaged beats is a reasonable surrogate for visual interpretation of the exercise ECG, making it a valuable source of confirmation of physician readings in large research trials and in clinical settings.

A comparison of quality of life scores in patients with angina pectoris after angioplasty compared with after medical therapy. Outcomes of a randomized clinical trial. Veterans Affairs Study of Angioplasty Compared to Medical Therapy Investigators.

BACKGROUND: Evaluations of therapy for the treatment of angina have traditionally consisted of a combination of objective measures, such as exercise tolerance, and subjective markers, such as angina attack rate. Recently, the need to assess "how patients feel"--their quality of life (QOL)--has been regarded with increasing importance. Standard instruments are available to assess QOL and its change after therapeutic intervention. Although QOL instruments have been used to assess the efficacy of percutaneous transluminal coronary angioplasty (PTCA), they have not been used previously to compare the impact of PTCA with that of medical therapy in patients with angina pectoris. We report on the changes in self-assessed QOL among patients randomly assigned to treatment by PTCA or medical therapy and relate these measurements to changes in exercise performance and coronary angiograms. METHODS AND RESULTS: Patients with stable angina, a positive exercise tolerance test, and at least 70% stenosis (index lesion) in the proximal two thirds of one major coronary artery were randomly assigned to receive PTCA or medical therapy. Six months after randomization, each patient underwent repeat exercise testing and coronary angiography. Before randomization and at the 6-month visit, patients completed a self-administered QOL questionnaire that measured physical functioning and psychological well-being. We compared the changes in QOL with changes between the baseline and 6-month exercise tests, stratified by terciles (decrease in duration, 0- to 2-minute increase, and > 2-minute improvement). We also stratified patients by whether there was more or less than 2 SD change (18.8%) in diameter stenosis of the index lesion (initial minus follow-up angiogram), and we related these to changes in QOL measures. One hundred eighty-two patients with one-vessel disease completed baseline and 6-month questionnaires. At baseline, there were no differences in any QOL measurements between treatment groups. At the 6-month follow-up visit, there was greater improvement in both physical functioning and psychological well-being scores for patients receiving PTCA (+7.36 +/- 15.6, PTCA; +1.98 +/- 14.7, medical therapy; P < .02). Improvement in QOL variables was noted only in patients demonstrating an increase in exercise performance. Also, patients assigned to either treatment whose angiograms demonstrated more than 18.8% improvement in index lesion percent stenosis experienced a significant increase in their QOL scores. CONCLUSIONS: This was the first study of the relative changes in QOL measures assessed with the use of previously validated and standardized instruments in patients randomly assigned to treatment with PTCA or medical therapy. Patients assigned to PTCA demonstrated a significantly greater improvement in both physical and psychological measures. This improvement was noted in patients whose exercise performance improved and whose angiograms demonstrated an improvement in lesion severity.

Relation between coronary artery stenosis assessed by visual, caliper, and computer methods and exercise capacity in patients with single-vessel coronary artery disease. The Veterans Affairs ACME Investigators.

BACKGROUND: Practitioners often assume a close relation between angiographic coronary artery stenosis and patient functional capacity. To test this unproven hypothesis, we analyzed the relation between coronary artery stenosis measured by different methods and maximal treadmill exercise tolerance in patients with single-vessel disease before and after intervention by percutaneous transluminal coronary angioplasty (PTCA). METHODS AND RESULTS: Coronary angiography and maximal exercise testing off anti-ischemic medication were performed before random assignment of 227 patients with single-vessel coronary artery disease to PTCA or drug therapy. Six months later, angiography and exercise testing were repeated with patients assigned to PTCA off anti-ischemic therapy so that the altered coronary stenosis was the only consistent variable. Patients assigned to drug therapy were exercised on drug therapy. Coronary stenosis was assessed visually by the local investigator and quantitatively by blinded caliper and computer methods in central laboratories. Variabilities of caliper and computer measurements were established in a subset read twice. Visually estimated stenosis > or = 90% at baseline was associated with shorter exercise duration (7.9 versus 9.2 minutes, P < .04). Similar segregation at baseline was not observed with caliper or computer methods. Regardless of the method of measurement used, correlation between changes of lesion severity and exercise duration from baseline to follow-up was poor. Patients were angiographically classified as "better," "unchanged," or "worse" if follow-up stenosis was below, within, or above 2 SD of mean technical variability from baseline (+/- 18.8%, caliper, +/- 14.6%, computer). Exercise duration for PTCA patients improved among those with better lesions (+2.4 minutes, n = 50, P = .001) but also among those with unchanged lesions (+1.9 minutes, n = 41, P < or = .001). Unchanged medically treated patients improved less (+0.5 minutes, n = 86, P = .04). Results were similar when patients were angiographically classified by minimum lumen diameter. CONCLUSIONS: Handheld calipers and quantitative coronary angiography are equivalent techniques for making anatomic measurements. Neither method identified patients having reduced exercise capacity at baseline as well as visual estimation. The relation between changes of coronary stenosis and exercise duration is highly variable, at least in part because of the insensitivity of angiographic methods for detecting small but potentially important changes. Minimal anatomic improvement 6 months after PTCA does not preclude a good functional outcome. Contrary to common belief, angiographic stenosis does not correlate well with functional capacity, even in patients with single-vessel disease.

Implications of third heart sounds in patients with valvular heart disease. The Veterans Affairs Cooperative Study on Valvular Heart Disease.

BACKGROUND: The presence of third heart sounds in patients with valvular heart disease is often regarded as a sign of heart failure, but it may also depend on the type of valvular disease. METHODS: We assessed the prevalence of third heart sounds and the relation between third heart sounds and cardiac function in 1281 patients with six types of valvular heart disease. RESULTS: The prevalence of third heart sounds was higher in patients with mitral regurgitation (46 percent) or aortic regurgitation (28 percent) than in those with aortic stenosis (11 percent) or mitral stenosis (8 percent). The left ventricular ejection fraction was significantly lower (P less than 0.001) when a third heart sound was detected in patients with aortic stenosis (0.38, vs. 0.56 in those without third heart sounds) or mixed aortic valve disease (0.40 vs. 0.55). However, the ejection fraction was only slightly lower in patients with mitral regurgitation and third heart sounds (0.51 vs. 0.57, P = 0.03). The pulmonary-capillary wedge pressure was higher (P less than 0.001) when a third heart sound was detected in patients with aortic stenosis (18.6 mm Hg, vs. 12.1 mm Hg in those without third heart sounds). There was no association between the wedge pressure and third heart sounds in patients with mitral regurgitation. The prevalence of third heart sounds increased with the severity of mitral regurgitation. CONCLUSIONS: In patients with mitral regurgitation, third heart sounds are common but do not necessarily reflect left ventricular systolic dysfunction or increased filling pressure. In patients with aortic stenosis, third heart sounds are uncommon but usually indicate the presence of systolic dysfunction and elevated filling pressure.

Accelerated coronary artery stenosis at a site proximal to coronary angioplasty.

Rapid progression of coronary stenosis has been described in patients undergoing percutaneous transluminal coronary angioplasty (PTCA), typically resulting in symptomatic angina 3 to 30 months postprocedure. We report a case of accelerated coronary stenosis in the instrumented vessel resulting in angina 3 days post-PTCA.

A comparison of angioplasty with medical therapy in the treatment of single-vessel coronary artery disease. Veterans Affairs ACME Investigators.

BACKGROUND: Despite the widespread use of percutaneous transluminal coronary angioplasty (PTCA), only a few prospective trials have assessed its efficacy. We compared the effects of PTCA with those of medical therapy on angina and exercise tolerance in patients with stable single-vessel coronary artery disease. METHODS: Patients with 70 to 99 percent stenosis of one epicardial coronary artery and with exercise-induced myocardial ischemia were randomly assigned either to undergo PTCA or to receive medical therapy and were evaluated monthly. The patients assigned to PTCA were urged to have repeat angioplasty if their symptoms suggested restenosis. After six months, all the patients had repeat exercise testing and coronary angiography. RESULTS: A total of 107 patients were randomly assigned to medical therapy and 105 to PTCA. PTCA was clinically successful in 80 of the 100 patients who actually had the procedure, with an initial reduction in mean percent stenosis from 76 to 36 percent. Two patients in the PTCA group required emergency coronary-artery bypass surgery. By six months after the procedure, 16 patients had had repeat PTCA. Myocardial infarction occurred in five patients assigned to PTCA and in three patients assigned to medical therapy. At six months 64 percent of the patients in the PTCA group (61 of 96) were free of angina, as compared with 46 percent of the medically treated patients (47 of 102; P less than 0.01). The patients in the PTCA group were able to increase their total duration of exercise more than the medical patients (2.1 vs. 0.5 minutes, P less than 0.0001) and were able to exercise longer without angina on treadmill testing (P less than 0.01). CONCLUSIONS: For patients with single-vessel coronary artery disease, PTCA offers earlier and more complete relief of angina than medical therapy and is associated with better performance on the exercise test. However, PTCA initially costs more than medical treatment and is associated with a higher frequency of complications.

Left ventricular function in rheumatic mitral stenosis.

Haemodynamic factors contributing to clinical disability in patients with rheumatic mitral stenosis have been under discussion and investigation for decades. Prior to the development of left heart catheterization, a low cardiac output in the presence of little or no pulmonary hypertension was taken as evidence for a myocardial 'insufficiency'. With the use of left heart catheterization, it was possible to exclude the presence of coronary artery disease and to assess directly the size and function of the left ventricle. Such studies indicate a tendency toward low-normal left ventricular end-diastolic volumes and low-normal ejection fractions. Modest reductions in the ejection fraction may be due to: (1) a restriction or tethering of posterobasal myocardium by the scarred mitral apparatus, or (2) abnormal interventricular septal motion related to right ventricular overload and unequal filling of the two ventricles. These and other factors, such as limited LV distensibility and variable diastolic suction, may affect ventricular function in rheumatic mitral stenosis. Thus, left ventricular dysfunction can generally be explained without implicating a rheumatic myocardial factor.

Routine electrocardiograms after cardiac catheterization. Are they useful?

In order to assess the value of routine electrocardiograms after cardiac catheterization (ECGs), 150 consecutive patients undergoing diagnostic cardiac catheterization were studied prospectively. The physician performing each catheterization was asked to rate his or her clinical index of suspicion that the electrocardiogram would be changed as a result of events during the procedure. Clinical index of suspicion and electrocardiograms were then compared for their ability to predict outcomes. Urgent clinical events within 24 hours of cardiac catheterization were defined as (1) new intensive care unit admission; (2) myocardial infarction; (3) coronary artery bypass graft surgery; (4) percutaneous transluminal coronary angioplasty; or (5) death. Chi square analysis demonstrated that neither ECGs (x2 = 2.12, p greater than 0.1) nor clinical index of suspicion (x2 = 2.43, p greater than 0.1) was better than chance alone in predicting urgent clinical events. The addition of ECGs to positive clinical index of suspicion did not increase the ability to predict urgent clinical events (x2 = 2.38, p greater than 0.1). Both ECGs and clinical index of suspicion were found to be relatively insensitive tests (sensitivity = 29% for ECGs, 43% for clinical index of suspicion). While both tests demonstrated high specificity, (89% for ECGs, 79% for clinical index of suspicion), their predictive value was equally poor (21% for ECGs, 17% for clinical index of suspicion). The addition of ECGs to clinical index of suspicion marginally increased the sensitivity of both tests to 50%. We conclude that routine postcatheterization electrocardiograms are no better at predicting urgent clinical events than clinical observation during catheterization alone, and should be performed only when index of suspicion dictates.

Simplified method for estimating true aortic valve mean gradient from simultaneous left ventricular and peripheral arterial pressure recordings.

Estimation of the aortic valve gradient by simultaneous recording of left ventricular and peripheral arterial pressures is subject to error due to delay and modulation of the arterial pressure contour as it propagates from the ascending aorta. This error can be corrected by averaging the mean gradients derived from unaltered and temporally aligned simultaneous left ventricular-peripheral arterial pressure tracings. In 26 patients with aortic stenosis and simultaneous recordings of ascending aortic and femoral arterial pressure we compared this method with a simplified approach in which the peripheral arterial pressure is partially aligned by advancing it against the left ventricular pressure by 50% of the time delay of the simultaneously recorded upstrokes. Gradients measured this way predicted the true aortic valve gradients (left ventricular-ascending aortic) with a mean difference of +1.1 mm Hg (range = +10 to -5 mm Hg). We recommend use of this simplified method of correction because it predicts true aortic valve gradient equally well as the averaging technique (r = 0.977 vs. 0.979) and requires half the time and effort.

Analysis of aortic valve gradients by transseptal technique: implications for noninvasive evaluation.

The peak instantaneous aortic valve gradient derived from Doppler echocardiography is commonly used to predict the severity of aortic stenosis. Peak instantaneous gradient should not be equated with the mean gradient or "peak to peak" gradient measured at cardiac catheterization. The primary purpose of this study is to assess the relationship between the aortic valve gradients, using a two-catheter transseptal technique in 102 patients with aortic stenosis, mixed aortic stenosis and regurgitation, and following aortic valve replacement. These cases were drawn from a series of 111 consecutive transseptal procedures for patients with isolated aortic valve disease. No major complications occurred, and the most common reason for technical failure was inability to engage the atrial septum in postoperative patients. Although the peak instantaneous gradient correlates well with the mean gradient in aortic stenosis (r = .94, P less than .001), mixed stenosis and regurgitation (r = .95, P less than .001), and after aortic valve replacement (r = .86, P less than .001), it systematically overestimates both the mean gradient and the peak to peak gradient. Neither the peak instantaneous nor the mean gradient correlates highly with aortic valve area in aortic stenosis (r = -.48, P less than .01 peak; r = -.58, P less than .001 mean gradient), mixed aortic stenosis and regurgitation (r = -.39, P NS peak; r = -.42, P NS mean gradient) or following aortic valve replacement (r = -.26, P NS peak; r = -.53, P less than .01 mean gradient). Systolic time intervals also were analyzed from the simultaneous left ventricular and ascending aortic pressure tracings.(ABSTRACT TRUNCATED AT 250 WORDS)

Complications of cardiac catheterization and angiography in patients with valvular heart disease. VA Cooperative Study on Valvular Heart Disease.

Complications were surveyed prospectively in 2,029 catheterizations performed on 1,483 patients from the 13 centers participating in the VA Cooperative Study on Valvular Heart Disease. Complications were reported in 6.9% of 1,559 preoperative procedures of which 2.6% were major and 0.2% fatal. Clinical predictors of complications were hypertension and the precatheterization diagnosis of aortic stenosis. Nevertheless, patients with aortic stenosis successfully tolerated left ventriculography, which was routinely performed regardless of the magnitude of gradient. Procedural predictors of complication were brachial arteriotomy (vascular occlusion) and transseptal catheterization (tamponade). Among the 470 postoperative catheterizations performed solely for research purposes, there were six complications, of which five were bleeding events in patients taking warfarin. Transseptal catheterization was safer in postoperative patients with no cases of tamponade in 125 procedures.

Six month postoperative hemodynamics of the Hancock heterograft and the Björk-Shiley prosthesis: results of a Veterans Administration cooperative prospective randomized trial.

In a Veterans Administration Cooperative Study involving 13 medical centers, 575 patients undergoing single valve replacement were prospectively randomized to receive either the standard Björk-Shiley prosthesis or the Hancock porcine heterograft (with a modified orifice for sizes 23 and smaller). The hemodynamic data in the 268 patients who underwent cardiac catheterization an average of 6 months (range 3 to 12) postoperatively are reported. Statistical analyses were performed on valve sizes 23, 25 and 27 in the aortic position, and 29, 31 and 33 in the mitral position. A wide variation was observed in mean pressure gradient and calculated orifice area in both valve types within all sizes in both the aortic and the mitral positions. In the aortic position, the Björk-Shiley prosthesis tended to have a lower pressure gradient and larger calculated orifice area than the Hancock heterograft, but the differences in gradient between the two valve types were significant only in the larger-sized valves. The difference in calculated area between the two valve types was not significant within each valve size. In the mitral position, there were no differences in gradient and calculated orifice area between the two types of prostheses. The postoperative cardiac index, regurgitant volume, pulmonary artery systolic and mean pressures, left ventricular end-diastolic pressure, left ventricular ejection fraction and left ventricular end-diastolic volume index did not differ in patients receiving the Björk-Shiley prosthesis from values in patients receiving the Hancock heterograft. Hence, the overall hemodynamic performance of both types of valves is remarkably similar. The choice between these two prostheses should, therefore, be governed not by the hemodynamic performance, but by other factors such as valve durability, risk of anticoagulation and incidence of valve-related complications.