Physiologic correlates of right ventricular ejection fraction in chronic obstructive pulmonary disease: A combined radionuclide and hemodynamic study

The pathophysiologic correlates of right ventricular ejection fraction, as well as its relation to contractile function as assessed by systolic pressure-volume data, were evaluated in 20 patients with chronic obstructive pulmonary disease. Radionuclide and hemodynamic measurements were obtained simultaneously. Baseline determinations were obtained in all patients. In seven patients, studies were repeated after intravenous administration of sodium nitroprusside. This procedure allowed characterization of right ventricular performance at decreased afterload and provided two points necessary for definition of the right ventricular systolic pressure-volume relation. Seventeen of the 20 patients had a depressed right ventricular ejection fraction (less than 45 percent). There was a strong inverse linear correlation between right ventricular ejection fraction and afterload as assessed by peak or mean pulmonary arterial pressure (r = ?0.81) and pulmonary vascular resistance index (r = ?0.73). Right ventricular ejection fraction also correlated, although less strongly, with preload as assessed by right ventricular end-diastolic volume index (r = ?0.56) and mean right atrial pressure (r = ?0.51). It did not correlate with cardiac index, the ratio of peak pulmonary arterial pressure to right ventricular end-systolic volume index, arterial oxygen tension or left ventricular ejection fraction. After nitroprusside administration, mean arterial pressure, peak pulmonary arterial systolic pressure and pulmonary vascular resistance index decreased significantly. The slope (E) and the volume intercept (V₀) of each pressure-volume line were determined. Administration of dobutamine resulted in a leftward shift from the endsystolic pressure-volume line. There were poor correlations between E and right ventricular ejection fraction, as well as between E and the control ratio between pulmonary arterial systolic pressure and end-systolic volume index.These data demonstrate that, in addition to intrinsic contractile influences, right ventricular ejection fraction is highly dependent on afterload, but less dependent on preload. Right ventricular ejection fraction is a poor indicator of the slope of the systolic pressure-volume relation, raising questions concerning its use as an independent index of chamber contractility.     

Assessment of cardiac performance with quantitative radionuclide angiocardiography: Right ventricular ejection fraction with reference to findings in chronic obstructive pulmonary disease

A reproducible noninvasive technique for measuring right ventricular ejection fraction was developed using first pass quantitative radionuclide angiocardiography. Studies were obtained in the anterior position with a computerized multicrystal scintillation camera with high count rate capabilities. Right ventricular ejection fraction was calculated on a beat to beat basis from the high frequency components of the background-corrected right ventricular time-activity curve. In 50 normal adults, right ventricular ejection fraction averaged 55 percent (range of 45 to 65 percent). This radionuclide measure of right ventricular function was reproducible, with minimal inter- and intraobserver variability and was sensitive to changes in inotropic state induced with isoproterenol. In 36 patients with chronic obstructive pulmonary disease, right ventricular ejection fraction ranged from 19 to 71 percent. All 10 patients with cor pulmonale, as well as 9 additional patients, had an abnormal right ventricular ejection fraction. Arterial oxygen tension and forced expiratory volume were depressed significantly more in patients with abnormal right ventricular ejection fraction than in subjects with normal right ventricular function. There was no relation between abnormalities in right and left ventricular ejection fraction.     

Augmentation of right ventricular performance in chronic obstructive pulmonary disease by terbutaline: A combined radionuclide and hemodynamic study

The acute hemodynamic and functional effects of the relatively selective beta₂ adrenoreceptor agonist, terbutaline, was evaluated in a well defined group of eight patients with chronic obstructive pulmonary disease, abnormal right ventricular performance and elevated pulmonary vascular resistance. Radionuclide and hemodynamic data were obtained simultaneously using first pass radionuclide angiocardiography and thermodilution pulmonary arterial catheterization. Terbutaline caused no change in right ventricular end-diastolic volume index but increased right ventricular stroke work index from 13 ±5 to 16 ± 6 g · m/m² (mean ± standard deviation; p < 0.025). Furthermore, pulmonary vascular resistance index decreased in all patients and for the group decreased from 623 ± 279 to 407 ± 204 dynes · s · cm^?5 · m² (p < 0.05). The extent of this decrease correlated linearly with the level of resting pulmonary vascular resistance (r = 0.76). Right ventricular ejection fraction increased significantly from 35 ± 10 to 46 ± 5 percent; terbutaline resulted in normalization (to greater than 45 percent) of the ejection fraction in five of the eight patients. The changes in right ventricular ejection fraction were greatest in patients with the highest level of pulmonary vascular resistance and the lowest baseline ejection fraction. Left ventricular ejection fraction also increased significantly from 62 ± 10 to 71 ± 10 percent; however, there was no correlation between the change in this variable and either systemic vascular resistance or baseline left ventricular ejection fraction. Systemic oxygen delivery increased from 45 ± 16 to 63 ± 19 ml/min per m² (p < 0.005) without any change in arterial oxygen tension. This study demonstrates that terbutaline results in substantial augmentation of right ventricular performance. This effect appears to be mediated predominantly through alterations in pulmonary vascular resistance. Terbutaline may provide significant cardiac benefits in addition to its salutory effects on the tracheobronchial tree.     

Contrasting acute effects of vasodilators (nitroglycerin, nitroprusside, and hydralazine) on right ventricular performance in patients with chronic obstructive pulmonary disease and pulmonary hypertension: A combined radionuclide-hemodynamic study

Fourteen patients with chronic obstructive pulmonary disease, mild to moderate pulmonary hypertension, and diminished right ventricular (RV) ejection fraction were studied acutely with use of a combined radionuclide-hemodynamic approach to assess and contrast the effects of 3 vasodilators on RV performance and central hemodynamic function. Nitroglycerin significantly decreased mean right atrial pressure, RV end-diastolic volume index, mean pulmonary artery pressure, cardiac index, and arterial oxygen tension, but did not affect pulmonary vascular resistance index and increased RV ejection fraction. Nitroprusside had similar effects on mean right atrial pressure, RV end-diastolic volume index, mean pulmonary artery pressure, cardiac index, and arterial oxygen tension, but also mildly decreased pulmonary vascular resistance index and did not alter RV ejection fraction. In contrast, hydralazine decreased pulmonary vascular resistance index and increased cardiac index and RV ejection fraction. The increase in ejection fraction correlated well with the decrease in pulmonary vascular resistance. These data suggest that in patients with mild to moderate secondary pulmonary hypertension, acute administration of hydralazine results in a substantial improvement in RV performance by virtue of decreasing pulmonary vascular resistance. In contrast, nitroglycerin and nitroprusside demonstrate predominant effects that reduce preload, cardiac index, and arterial oxygen tension. Based on these data, afterload reduction with vasodilators such as hydralazine may be potentially useful in selected patients with pulmonary disease and secondary pulmonary hypertension and appear preferable to agents that primarily reduce preload. Further long-term studies are necessary to establish therapeutic efficacy.     

Radionuclide assessment of right and left ventricular exercise reserve after total correction of tetralogy of Fallot

First pass radionuclide angiocardiography under conditions of rest and exercise was utilized to evaluate a group of 16 postoperative patients who had undergone total surgical correction of tetralogy of Fallot. Functional data were related to thallium-201 myocardial imaging at rest, a noninvasive means of detecting right ventricular hypertrophy. All 16 patients were asymptomatic and 15 demonstrated normal right ventricular ejection fraction (equal to or greater than 45 percent) at rest. However, 13 patients manifested abnormal right ventricular ejection fraction responses to exercise (normal response is an absolute increment in an ejection fraction of 5 or greater percent). For the entire group, right ventricular ejection fraction at rest was 55 ± 2 percent, whereas at exercise it was 52 ± 2 percent (p = not significant). In contrast, left ventricular ejection fraction responses were normal in all patients. Thallium-201 imaging revealed substantial right ventricular uptake consistent with residual right ventricular hypertrophy, which was quantifiable in all patients. Thus, abnormalities in right ventricular performance during exercise may be detected readily by this radionuclide approach in these postoperative patients despite their asymptomatic clinical status and generally normal right ventricular performance at rest.     

Variability in sequential measures of left ventricular performance assessed with radionuclide angiocardiography

The variability of left ventricular ejection fraction, normalized mean ejection rate and regional wall motion was evaluated from first pass quantitative radionuclide angiocardiograms obtained with a computerized multicrystal scintillation camera. Three radionuclide studies separated by an average of 4.3 days were obtained in each of 20 patients. Ejection fraction and ejection rate obtained on the first, second and third studies did not differ significantly. The mean (± standard deviation) variability of sequential ejection fraction measurement was 4.4 ± 3.6 percent, and of sequential ejection rate was 0.56 ± 0.47 sec^?1. Variations in measurements were not related to fluctuations in heart rate or blood pressure. Variability in ejection rate was significantly greater in patients with normal function than in those with abnormal function. Regional wall motion analysis was constant in 19 of 20 patients. Thus, sequential quantitative radionuclide angiocardiography allows reproducible serial assessment of left ventricular performance that can be performed with a low level of intrinsic variability.     

Continuous monitoring of left ventricular performance with the computerized nuclear probe during laryngoscopy and intubation before coronary artery bypass surgery

Left ventricular performance was monitored serially in 25 patients during laryngoscopy and intubation in the anesthetic induction period before elective coronary artery bypass surgery using the labeled equilibrium blood pool and the computerized nuclear probe. Left ventricular ejection fraction was obtained preoperatively, after induction of anesthesia but before endotracheal intubation, immediately after intubation, and at 1 minute intervals thereafter for 10 minutes. In all patients, there was an immediate decrease (mean 16%) in left ventricular ejection fraction accompanying the reflex hypertension and tachycardia occurring during laryngoscopy and endotracheal intubation; it was significantly depressed for 3 minutes with the concomitant hemodynamic changes. Seven patients did not demonstrate a recovery of left ventricular ejection fraction to the preintubation value. In 10 healthy noncardiac patients undergoing orthopedic surgery, after an identical anesthetic induction sequence and intubation, there was a similar decrease in ejection fraction, but of shorter duration. In these patients the recovery of left ventricular performance preceded the recovery of blood pressure and heart rate.This study demonstrates that profound decreases in left ventricular performance accompany the reflex hypertension and tachycardia occurring during endotracheal intubation and that there is persisting depression of left ventricular function in some patients with coronary artery disease. These findings indicate the potential utility of the computerized nuclear probe for monitoring ventricular performance during this critical period.     

Multiple gated cardiac blood pool imaging for left ventricular ejection fraction: Validation of the technique and assessment of variability

The intrinsic variability and accuracy of left ventricular ejection fraction determined by multiple gated cardiac blood pool imaging was evaluated in 83 patients. Ejection fraction by gated studies correlated well with data from first pass radionuclide angiocardiography (r = 0.94) and from contrast angiography (r = 0.84). Intra- and interobserver variabilities of absolute ejection fraction were minimal (mean ± standard deviation 1.4 ± 1.2 and 1.6 ± 1.5 percent, respectively) and were not different for normal (ejection fraction 55 percent or greater) and abnormal patients. Ejection fraction was determined twice in 70 patients: on the same day at intervals separated by 1 to 2 hours (41 patients) and on 2 different days (29 patients). Ejection fraction ranged from 18 to 91 percent and was normal in 37 patients. There was no difference in mean aerial variabilities of absolute ejection fraction for all repeat studies performed on the same and separate days (3.3 ± 3.1 versus 4.3 ± 3.1 percent (not significantly different). The mean variability of absolute ejection fraction for repeat studies in normal patients was significantly greater than in abnormal patients (5.4 ± 4.4 versus 2.1 ± 2.0 percent, P < 0.01). The incidence rate of absolute interstudy changes of 5 percent or more was significantly higher in normal than in abnormal patients (P < 0.01). This differential variability should be considered in interpreting sequential changes in left ventricular ejection fraction. To be attributed to nonrandom physiologic alterations, the absolute change in ejection fraction should be 10 percent or more in normal patients and 5 percent or more in abnormal patients.     

Variability of repetitive arrhythmia formation in patients with chronic ventricular arrhythmia

The statistical frequency of ventricular couplet formation was determined in 125 long-term electrocardiographic recordings obtained from patients both with and without cllnical cardiovascular disease. The repetition index, defined as the ratio of couplets to isolated premature ventricular complexes, was found to vary widely, from 0 to $\text{333}\text{1,000}$, and was not related to the underlying frequency of premature ventricular complexes. The reproducibility of the repetition index was examined and in 19 (83 percent) of 23 patients remained either above or below $\text{10}\text{1,000}$ premature ventricular complexes on two separate electrocardiographic recordings. In electrocardiograms from patients with known cardiovascular disease, coexistent nonsustained ventricular tachycardia was noted in 8 (15 percent) of 53 with a repetition index of less than $\text{10}\text{1,000}$ premature ventricular complexes and 34 (62 percent) of 55 with a repetition index value of more than $\text{10}\text{1,000}$ (p <0.001). In patients without clinical evidence of cardiovascular disease, ventricular tachycardia occurred in 2 (20 percent) of 10 recordings with a repetition index of less than $\text{10}\text{1,000}$ premature ventricular complexes and in 5 (71 percent) of 7 with a repetition index of more than $\text{10}\text{1,000}$ (p <0.05). In patients who had two electrocardiograms analyzed, ventricular tachycardia was found at least once in 1 (10 percent) of 10 patients whose repetition index was always less than $\text{10}\text{1,000}$ premature ventricular complexes and in 11 (85 percent) of 13 patients whose repetition index was 10 or more/1,000 on either or both recordings (p < 0.001). A high repetition index was also found to be predictive of future occurrence of ventricular tachycardia in five of six patients whose index recording showed no tachycardia but a repetition index of at least $\text{10}\text{1,000}$ premature ventricular complexes. These observations suggest that (1) quantitative approaches to complex ventricular arrhythmia are useful, and (2) the repetition index is a reflection of some aspect of ventricular vulnerability.     

Global and regional left ventricular response to bicycle exercise in coronary artery disease. Assessment by quantitative radionuclide angiocardiography.

The left ventricular response to bicycle exercise was evaluated in 60 patients with coronary artery disease and in 13 normal control subjects. Left ventricular ejection fraction, mean normalized ejection rate and regional wall motion were determined using first-pass radionuclide angiocardiograms obtained at rest and again during peak graded bicycle exercise. All normal subjects demonstrated improved left ventricular function with exercise. Left ventricular ejection fraction increased significantly from 67 ± 3 per cent (mean ± SE) at rest to 82 ± 4 per cent with exercise (p < 0.001). Similarly, the left ventricular ejection rate increased significantly from 3.47 ± 0.31 sec^?1 to 6.53 ± 0.42 sec^?1(p < 0.001). In contrast, in 44 of 60 patients with coronary artery disease, the ejection fraction or ejection rate either decreased or remained the same with exercise. New or exaggerated regional wall motion abnormalities were detected in 28 of 60 patients with coronary artery disease. Over-all, global or regional evidence of compromised left ventricular reserve was found in 48 of 60 patients with coronary artery disease.The major determinant of an abnormal left ventricular response to exercise was the presence or absence of electrocardiographic evidence of myocardial ischemia. Left ventricular ejection fraction decreased or remained the same with exercise in all patients with coronary artery disease and electrocardiographic ischemia. New regional wall motion abnormalities were detected in 20 of these patients. In this group, the left ventricular ejection fraction decreased from 66 ± 2 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001), whereas the ejection rate was unchanged by exercise (rest 3.33 ± 0.21 sec^?1; exercise 3.34 ± 0.22 sec^?1, p > 0.05). Of the 30 patients with coronary artery disease who exercised to symptom-limiting fatigue without electrocardiographic ischemia, 18 demonstrated compromised left ventricular reserve with exercise. Twelve of the remaining patients with coronary artery disease had normal left ventricular reserve, in eight of whom ventricular function was completely normal both at rest and during exercise. In this group exercised to fatigue, the left ventricular ejection fraction increased from 53 ± 4 per cent at rest to 58 ± 2 per cent with exercise (p < 0.001). The ejection rate also increased from 2.48 ± 0.24 sec^?1 to 3.67 ± 0.39 sec^?1 (p < 0.001). The direction and magnitude of the left ventricular responses to exercise were not affected by long-term oral propranolol administration in 22 patients. Based upon either abnormal exercise left ventricular reserve or abnormal global and regional left ventricular function at rest, the over-all sensitivity of this radionuclide technic for the detection of coronary artery disease was 87 per cent (52 of 60 patients). These data demonstrate that exercise ventricular performance studies provide important physiologic insights into left ventricular functional reserve as well as a sensitive noninvasive approach for the detection of coronary artery disease.     

Effects of aminophylline upon right and left ventricular performance in chronic obstructive pulmonary disease: Noninvasive assessment by radionuclide angiocardiography

Although aminophylline is a widely used bronchodilator in chronic obstructive pulmonary disease (COPD), its effects upon cardiac performance have not been fully established. The effect of aminophylline upon right ventricular and left ventricular ejection fraction and the left ventricular ejection rate was evaluated by first-pass quantitative radionuclide angiocardiography in 15 patients with COPD, including four with cor pulmonale, and in five control subjects without cardiopulmonary disease. Aminophylline infusion (9 mg/kg) significantly increased the right ventricular ejection fraction (45 to 52 per cent), left ventricular ejection fraction (60 to 67 per cent) and left ventricular ejection rate (3.4 to 4.1 sec^?1) in patients with COPD (all parameters, p < 0.001). In six of eight patients with depressed control right ventricular performance, right ventricular ejection fraction normalized and in two of five patients with depressed control left ventricular performance, the left ventricular ejection fraction and left ventricular ejection rate normalized. In control subjects, comparable increases were noted in the right ventricular ejection fraction (50 to 56 per cent), left ventricular ejection fraction (62 to 71 per cent) and left ventricular ejection rate (3.2 to 4.6 sec^?1) (p < 0.001). One-second forced expiratory volume (FEV₁) and forced vital capacity (FVC) increased significantly in patients with COPD but not in control subjects. Arterial carbon dioxide tension decreased significantly in both groups (p < 0.05), whereas arterial oxygen tension did not change. Theophylline blood levels did not correlate with absolute increases in right ventricular or left ventricular ejection fraction.These data indicate that aminophylline acutely enhances biventricular performance in COPD. Since comparable cardiovascular changes are induced in normal subjects in whom ventilatory function was not altered, the beneficial effects of aminophylline upon global ventricular performance appear to be independent of the degree of pulmonary compromise.     

Left ventricular filling in differentiating restrictive amyloid cardiomyopathy and constrictive pericarditis

Left ventricular filling was evaluated with use of digitized left ventriculograms in patients with (1) restrictive amyloid cardiomyopathy, (2) constrictive pericarditis, and (3) a normal heart. Restrictive cardiomyopathy (four patients) was established by right and left heart hemodynamic studies and postmortem examination; all four patients had cardiac amyloidosis. Constrictive pericarditis (seven patients) was established by characteristic right and left heart catheterizatlon data and pericardial disease at operation; four patients had calcific and three had noncalcific anatomic changes. Normal subjects (seven patients) had normal intracardiac pressures and normal findings on left ventriculography and coronary arteriography.Left ventriculographic silhouettes were digitized and left ventricular volumes were calculated by computer at 16 ms intervals. Curves of left ventricular volume and ventricular filling rate were constructed for each patient and also for each group. Patients with restrictive amyloid cardiomyopathy had no plateau in the diastollc left ventricular filling volume curve, and their left ventricular filling rate was slower than normal during the first half of diastole. Patients with constrictive pericarditis had a sudden and premature plateau in the diastolic left ventricular volume filling curve. In addition, the left ventricular filling rate was faster than normal during the first half of diastole. Statistical analysis of left ventricular filling rate in patients with restrictive amyloid cardiomyopathy, patients with constrictive pericarditis and normal patients showed significant differences during the first half of diastole; those with restrictive amyloid cardiomyopathy had 45 ± 4 percent, those with constrictive pericarditis had 85 ± 4 percent and normal subjects had 65 ± 5 percent of left ventricular filling completed at 50 percent of diastole (p < 0.05).Thus, this study showed a significantly different profile of diastolic left ventricular filling volume and ventricular filling rate curves during the first half of diastole in patients with restrictive cardiomyopathy and those with constrictive pericarditis. The findings suggest the importance of these determinations in differentiating restrictive amyloid cardiomyopathy and constrictive pericarditis at cardiac catheterization.     

Retrograde left ventricular catheterization in patients with an aortic valve prosthesis

Twenty-seven consecutive patients with an aortic valve prosthesis were evaluated with retrograde left ventricular catheterization. The prosthesis was successfully crossed, permitting hemodynamic and angiographic evaluation of function of the prosthetic valve, left ventricle and mitral valve in all 27 cases. No complications were encountered. In patients with active endocarditis or recent embolization, the retrograde technique was avoided when possible, and attempts were made to utilize other techniques for study. However, three such patients were evaluated with the retrograde technique without complication. Examination of pressure tracings and cineangiographic films suggested only minor interference with valve poppet movement induced by the catheter transversing the valve. In three cases, hemodynamic data were recorded with the catheter crossing the prosthesis at one time and a paraprosthetic valve defect at another time. Identical gradients were recorded. This series documents the safety and efficacy of the retrograde approach, which is proposed as an alternative to the transseptal technique and left ventricular puncture.     

Effects of oral digoxin on ventricular ectopy and its relation to left ventricular function

The ventricular antiarrhythmic properties of oral digoxin were examined in 13 patients with chronic ventricular ectopy using serial 24-hour electrocardiographic monitoring. Mean premature ventricular complex frequency (per 1,000 normal beats) decreased from 56 +/- 47 during the placebo period to 40 +/- 27 (p = not significant [NS]) and 25 +/- 17 (p less than 0.05) during daily administration of digoxin, 0.25 and 0.375 mg. Digoxin had no significant effect on the qualitative occurrence of complex ventricular arrhythmia patterns (multiformity, bigeminy, couplets, ventricular tachycardia). Radionuclide left ventricular (LV) ejection fraction was measured during the placebo period. Seven patients had normal (ejection fraction greater than 50%) and 6 abnormal global LV performance. In the normal group, the mean premature ventricular complex frequency decreased from 69 +/- 58 to 20 +/- 18 (p less than 0.05) and the mean couplet frequency decreased from 0.59 +/- 0.85 to 0.07 +/- 0.06 (p less than 0.04) during the placebo and 0.375 mg digoxin dosing periods, respectively. In contrast, no significant changes in either variable occurred after digoxin in subjects with depressed LV function. This study indicates that oral digoxin is moderately effective in suppressing premature ventricular complexes, and that its effects are greatest in patients with normal overall LV performance.     

Relations between ventricular refractoriness and regional myocardial blood flow after acute coronary occlusion

Myocardial ischemia has been associated with dispersion of ventricular refractory periods and this dispersion has been related to the ventricular arrhythmias seen with coronary occlusion. This study relates the degree of change in measured ventricular refractory period with the degree of regional myocardial blood flow abnormality after coronary occlusion. When regional myocardial blood flow is less than 70 percent of that of nonischemic areas, refractory periods are significantly (P < 0.001) shortened. The greatest change in refractory periods occurs in areas with a regional myocardial blood flow that is 21 to 40 percent of that of non-ischemic areas. Marked (less than 20 percent) and minimal (61 to 80 percent) reductions in regional myocardial blood flow are associated with less, but still significant, shortening of ventricular refractory periods. Thus dispersion of refractoriness can be related to the inhomogeneity of regional myocardial blood flow after acute coronary occlusion. Interventions designed to salvage ischemic myocardium by increasing regional myocardial blood flow may affect dispersion of ventricular refractory periods in complex and divergent ways.     

Surgical approach for patients with unstable angina pectoris: role of the response to initial medical therapy and intraaortic balloon pumping in perioperative complications after aortocoronary bypass grafting.

The role of the response to initial medical therapy and intraaortic balloon pumping in perioperative complications was evaluated in 194 consecutive patients with unstable angina pectoris who underwent cardiac catheterization and coronary surgery from July 1975 through December 1977. Sixty-four patients (33 percent) responded to medical therapy within 48 hours after the initiation of full medical therapy in the coronary care unit and underwent elective cardiac catheterization and coronary surgery; 130 patients (67 percent) did not respond to medical therapy. Of these 130 patients, 75 (58 percent) received the preoperative assistance of an intraaortic balloon pump and underwent emergency cardiac catheterization and surgery. Fifty-five patients (42 percent) of the medical non-responders were not treated with an intraaortic pump and underwent emergency cardiac catheterization and surgery. Chi square analysis revealed that the clinical characteristics of the patients in all three groups were similar.The overall rate of operative mortality was 6.1 percent. Medical responders had no operative mortality, medical nonresponders with intraaortic balloon pumping had an operative mortality rate of 5.3 percent and medical nonresponders without balloon pumping a rate of 14.5 percent. The overall incidence rate of perioperative myocardial infarction was 13 percent; it was 6 percent in medical responders, 6.6 percent in nonresponders with intraaortic balloon pumping and 29 percent in non-responders without intraaortic balloon pumping. Thus, this study suggests that perioperative complications can be minimized by initial aggressive medical therapy. If this therapy fails, intraaortic balloon counterpulsation can produce a reduction in perioperative complications similar to that produced by medical therapy.     

Ventricular arrhythmias late after aortic valve replacement and their relation to left ventricular performance

Sudden unexplained death is a common cause of late mortality after aortic valve replacement. To evaluate the occurrence of ventricular arrhythmia in patients with aortic valve replacement, two 24 hour ambulatory electrocardiographic recordings were obtained in 45 such patients (mean age 55 years) who had undergone replacement an average of 3.3 years previously. In 43 patients, ventricular arrhythmia was detected; it was rare (mean premature ventricular complex frequency less than $\text{1}\text{15}$ min) in 18 patients (40 percent), moderately frequent (mean frequency $\text{1?}\text{10}\text{15}$ min) in 14 patients (31 percent) and frequent (mean frequency more than $\text{10}\text{15}$ min) in 11 patients (24 percent). Multiformity was noted in 40 (89 percent), bigeminy in 27 (60 percent), couplets in 27 (60 percent) and ventricular tachycardia in 16 (36 percent) of the 45 patients studied. The occurrence of ventricular arrhythmia was not related to the predominant hemodynamic lesion or to the presence of coronary artery disease as determined at the time of preoperative cardiac catheterization. Radionuclide left ventricular ejection fraction, determined at the time of electrocardiographic monitoring in 39 patients, demonstrated normal left ventricular function (ejection fraction greater than 50 percent) in 27 patients (60 percent), moderately depressed function (ejection fraction 36 to 50 percent) in 8 (21 percent) and severe dysfunction in 4 (10 percent). When patients with abnormal versus normal left ventricular performance were compared, the mean premature ventricular complex frequency was $\text{21 ±}\text{26}\text{15}\text{min}\text{versus}\text{5 ±}\text{11}\text{15}\text{min (}\text{p}\text{< 0.01)}$; couplets occurred in 10 (83 percent) of 12 versus 13 (48 percent) of 27 patients (p < 0.05) and ventricular tachycardia in 8 (75 percent) of 12 versus 6 (22 percent) of 27 patients (p < 0.01). Patients exhibiting ventricular tachycardia had a mean left ventricular ejection fraction of 47 ± 14 percent compared with 62 ± 13 percent in patients without this arrhythmia (p < 0.005). This study indicates that significant ventricular arrhythmias, including ventricular tachycardia, are common late after aortic valve replacement. In addition, a relation exists between occurrence of arrhythmia and left ventricular function abnormalities.