Early changes in left ventricular size and function after correction of left ventricular volume overload

The ability to predict early postoperative left ventricular size and function in patients with isolated aortic or mitral regurgitation was determined utilizing multigated blood pool imaging before and 2 to 4 weeks after valve replacement (aortic valve, 20 patients; mitral valve, 20 patients). Early postoperatively, ejection fraction decreased significantly (p <0.001) in both patient groups (from 0.55 ± 12 to 0.40 ± 0.14 [mean ± 1 standard deviation] in patients with aortic regurgitation and from 0.66 ± 0.09 to 0.48 ± 0.11 in patients with mitral regurgitation). The decrease in ejection fraction was associated with a large decrease in stroke volume with minimal or no change in end-systolic volume; it was unrelated to the preoperative ejection fraction. Early postoperative ejection fraction correlated best with preoperative end-systolic volume and was normal in 14 (67 percent) of 21 patients with a preoperative ejection fraction above 0.60; 4 (27 percent) of 15 patients with a preoperative ejection fraction of 0.50 to 0.60; and in 0 of 4 patients with a preoperative ejection fraction below 0.50 (p <0.05). In addition, a repeated scan in 16 patients late (1 to 2 years) after operation showed a further reduction in endsystolic volume in patients with aortic regurgitation with an increase in ejection fraction toward preoperative values. There was no significant change in patients with mitral regurgitation.End-diastolic volume decreased significantly (p <0.001) early postoperatively (from 162 ± 60 to 102 ± 41 ml/m² in patients with aortic regurgitation and from 131 ± 40 to 78 ± 30 ml/m² in patients with mitral regurgitation). This decrease was closely related to a decrease in stroke volume and was unrelated to preoperative ejection fraction. Early postoperative end-diastolic volume correlated best with the preoperative end-systolic volume. The major part of the reduction in end-diastolic volume occurred within 2 weeks of valve replacement.Removal of chronic left ventricular volume overload due to aortic or mitral regurgitation produces a decrease in ejection fraction and end-diastolic volume. The early reduction is in part a result of altered loading conditions and may not necessarily imply alterations in myocardial contractile function. The reduction in ejection fraction appears to persist in patients with mitral regurgitation.     

Relation of segmental wall motion to global left ventricular function in acute myocardial infarction

The relation of left ventricular regional wall motion to global ventricular function was evaluated by radionuclide ventriculography in 127 patients within 18 hours of acute myocardial infarction. No patient had evidence of previous myocardial infarction. The following parameters were measured: (1) wall motion index; (2) percent of abnormally contracting segment; (3) ejection fraction (EF); (4) end-diastolic volume (EDV) and end-systolic volume (ESV); and (5) peak systolic cuff pressure/end-systolic volume ratio ($\text{PSP}\text{ESV}$). The measurements of global function correlated well with wall motion index (r = 0.83, p < 0.001 for EF; r = ?0.69, p < 0.001 for ESV; and $\text{r}\text{= 0.061,}\text{p}\text{< 0.001}\text{for}\text{PSP}\text{ESV}$), but EDV correlated less well (r = ?0.35, p < 0.001). Multiple linear regression analysis revealed that EF correlated best with wall motion index, and no other parameters of global left ventricular function added significantly to the regression.The correlation of motion in each segment with EF was determined by multiple linear regression analysis. Ejection fraction correlated best with motion in the anterobasal, then in order of correlation, in the apical-septal, inferoapical, anterolateral, and superlateral walls. The relation of EDV, ESV, and degree of percent abnormally contracting segments was as follows: EDV did not increase with a mild regional wall motion abnormality; however, ESV did increase and reduced stroke volume. As percent abnormally contracting segments worsened, enlargement of both EDV and ESV was seen and was associated with further reduction in systolic volume.These data suggest that EF is the best global left ventricular function correlate of the severity of the regional wall motion abnormality, and that abnormal motion in the territory of the left anterior descending coronary best predicts reduction in global left ventricular function. Radionuclide ventriculography is useful in characterizing global and regional left ventricular function in the early hours of acute myocardial infarction.     

Comparison of high pulse repetition frequency and continuous wave Doppler echocardiography in the assessment of high flow velocity in patients with valvular stenosis and regurgitation

Continuous wave Doppler echocardiography has proved useful in detecting and quantitating the high velocity flow disturbances that characterize many stenotic and regurgitant valvular lesions. Pulsed Doppler echocardiography, in contrast, is limited in its ability to quantitate the high velocities that are detected. Recently, new pulsed Doppler systems have been developed that employ high pulse repetition frequencies and can theoretically measure higher flow velocities than those measured by the standard pulsed Doppler systems. To determine the ability of high pulse repetition frequency Doppler echocardiography to accurately measure high velocity flow signals in comparison with the continuous wave method, 80 patients undergoing routine echocardiographic examination for the assessment of valvular heart disease were studied using both techniques. A total of 113 high velocity flow disturbances were detected in 68 patients. In 41 instances, the maximal velocities by the two methods were within 0.5 m/s of each other. In 68 of the 113 high velocity lesions, however, the high pulse repetition frequency technique underestimated the peak velocity found with continuous wave Doppler echocardiography by more than 0.5 m/s. Comparison of the peak velocities recorded by the two methods for the total group showed no significant correlation (r = 0.04, p = NS). Comparison of the difference in peak velocities obtained by the two techniques with the maximal continuous wave velocity (n = 94, r = 0.70, slope = 0.71) suggested that the underestimation becomes greater as the peak velocity increases. Fifteen of the study patients with aortic stenosis subsequently underwent catheterization.(ABSTRACT TRUNCATED AT 250 WORDS)     

Scintigraphic evaluation of left ventricular aneurysm

Gated cardiac blood pool scintigraphy is a noninvasive method to assess regional and global left ventricular function in the patient with suspected true or false left ventricular aneurysm after a myocardial infarction. The procedure is easy to perform and provides reproducible, high resolution images that can accurately distinguish regional from diffuse contractile abnormalities often present after myocardial infarction. An overall accuracy rate of 96 percent for detection of left ventricular aneurysm can be obtained with gated cardiac blood pool scintigraphy as compared with contrast left ventriculography. The procedure also permits assessment of functional reserve of the noninvolved myocardium and thus can provide valuable information on whether enough viable myocardium will remain after aneurysmectomy. The addition of thallium-201 myocardial perfusion scintigraphy may aid in the separation of viable from scarred myocardium at the edge of the aneurysm. Both radionuclide techniques are well suited for screening the patient after infarction with persistent congestive heart failure, malignant arrhythmia or systemic emboli in whom a left ventricular aneurysm may have developed.     

Effects of coronary bypass grafting on resting left ventricular contraction in patients studied 1 to 2 years after operation.

Left ventricular contraction was evaluated with angiography in 51 patients 1 to 2 years after coronary arterial bypass surgery. The left ventricle was classified into five segments, and segmental ventricular wall motion was analyzed with subjective and objective methods. With subjective analysis, 25 percent of asynergic segments showed improvement, 72 percent no change and 3 percent deterioration in contraction. There was a 5 percent incidence rate of new wall motion abnormalities in segments that were judged normal from the preoperative ventriculogram. Objective analysis revealed significant improvement in contraction of asynergic segments in each of the five left ventricular segments analyzed. Thus, 1 to 2 years after coronary bypass surgery, there was a significant reduction in left ventricular segmental wall motion abnormalities, and the incidence of deterioration in contraction was small.     

Right ventricular infarction. Clinical diagnosis and differentiation from cardiac tamponade and pericardial constriction.

Twelve patients with a clinical diagnosis of right ventricular infarction are described. All had acute inferior wall myocardial infarction associated with the bedside findings of jugular venous distension, clear lungs on auscultation, and arterial hypotension. Hemodynamically, there was elevation of right-sided filling pressures not explained by normal or minimally elevated pulmonary wedge pressures. Four patients had an incorrect diagnosis of acute cardiac tamponade. However, a review of the data showed that the hemodynamic features of right ventricular infarction more closely resemble those of pericardial constriction, a point that may be helpful in distinguishing right ventricular infarction from cardiac tamponade. Invasive and noninvasive techniques that exclude the presence of pericardial fluid and suggest enlargement and abnormal contractility of the right ventricle were helpful in establishing the diagnosis of right ventricular infarction in several patients.     

Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia. The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias.     

An ambulatory ventricular function monitor: validation and preliminary clinical results

A device for the continuous measurement of left ventricular (LV) function was tested in a series of 34 subjects. The instrument consisted of 2 arrays of radiation sensitive cadmium telluride detectors held in place over the region of the left ventricle and lung by a vest-like garment (hence the name VEST). The VEST electronic instrumentation included analog-to-digital converters, a battery pack, microprocessor and gating device, which were worn in a back pack. Data generated by the VEST, including the digitized average electrocardiogram, RR interval, counts/13 ms in each radiation detector, and time since commencement of data recording, were recorded on a cassette tape recorder every 2 minutes for subsequent analysis. At the conclusion of conventional multigated blood pool imaging, the VEST was positioned and worn by the subjects while supine, standing in place and walking. The correlation of ejection fraction calculated independently from the VEST and scintillation camera data was greater than 0.95. The inter-record reproducibility of the ejection fraction measured by the VEST in sedentary subjects was less than 3%.     

Long-term reproducibility of responses to programmed cardiac stimulation in spontaneous ventricular tachyarrhythmias

Programmed electrical stimulation (PES) of the heart has been used to initiate and terminate ventricular tachyarrhythmias under controlled conditions in patients in whom these arrhythmias have occurred spontaneously. The long-term reproducibility of the response to programmed cardiac stimulation in patients with ventricular arrhythmias is unknown. Seventeen patients with previously documented spontaneously occurring ventricular tachyarrhythmias were evaluated: 5 with nonsustained ventricular tachycardia (VT), 10 with sustained VT and 2 with ventricular fibrillation. The underlying cardiac diagnosis was atherosclerotic coronary heart disease (CAD) in 11 patients, dilated cardiomyopathy in 2 patients, congenital heart disease in 1 patient and no structural heart disease in 3. All patients underwent PES in the absence of antiarrhythmic drug treatment, and patients with inducible VT underwent serial electrophysiologic-pharmacologic testing in an attempt to suppress the arrhythmia. All 17 patients were reexamined with PES at a mean of 18 months (range 2 to 42) after their initial electrophysiologic study, during which time none had a myocardial infarction or intervening cardiac surgery. Repeat electrophysiologic studies, performed in the absence of antiarrhythmic agents, were undertaken because of drug intolerance, availability of new drugs, recurrent arrhythmia or preoperative reevaluation. All 11 patients with CAD had inducible VT on both the first and second electrophysiologic evaluation. Of the 6 patients with no CAD, only 1 had inducible VT on both occasions. Thus, long-term reproducibility of PES-induced VT in patients with stable CAD appears to be high.     

Contrast echocardiography in acute myocardial ischemia. II. The effect of site of injection of contrast agent on the estimation of area at risk for necrosis after coronary occlusion

Myocardial contrast echocardiography has been shown to accurately assess the area at risk for necrosis after acute coronary occlusion in the experimental model. The area at risk as determined by this method, however, has been defined in different ways depending on the model used. Some investigators have injected the contrast agent proximal to the site of coronary occlusion (left main coronary artery or aorta) and defined the area at risk as the segment of myocardium not showing a contrast effect (negative risk area). Others have injected the contrast agent directly into the occluded vessel and have defined the area at risk as that showing contrast enhancement (positive risk area). To evaluate whether the areas at risk determined by these two techniques are identical, six open chest dogs were studied using both methods. The area at risk was slightly but significantly larger when the contrast agent was injected into the occluded vessel than when it was injected proximally into the left main coronary artery (4.98 +/- 1.69 versus 3.97 +/- 1.27 cm2, p less than 0.01). It is concluded that the site of injection of the contrast agent significantly influences the determination of area at risk. Therefore, data obtained by the two techniques should not be used interchangeably, and in a given study the area at risk should be measured consistently using one technique.     

Right ventricular function in adult atrial septal defect: Preoperative and postoperative assessment and clinical implications

Right ventricular function was assessed with gated cardiac blood pool scanning in 20 adult patients with an atrlal septal defect. All patients had scans both before and 6 or more months after surgical repair of the defect. Clinical findings, pre- and postoperative course and cardiac catheterization data were correlated with scan findings. In all 20 patients, the right ventricle was dilated preoperatively. In nine patients (aged 18 to 42 years, mean 25), right ventricular wall motion was normal preoperatively. All nine were asymptomatic and had normal sinus rhythm. Their pulmonary to systemic flow ratio ranged between 2:1 and 5:1, pulmonary arterial systolic pressure between 18 and 30 mm Hg and right ventricular end-diastolic pressure between 0 and 8 mm Hg. After repair of the atrlal septal defect, all nine remained asymptomatic, right ventricular size decreased dramatically and wall motion was normal.In the remaining 11 patients (aged 36 to 63 years, mean 52), there was moderate to severe preoperatlve right ventricular hypokinesia. All had preoperatlve symptoms (functional class II and III, New York Heart Association); six had atrial fibrillation and five had normal sinus rhythm; seven had clinical heart failure. Pulmonary to systemic flow ratio ranged between 1.7:1 and 5.0:1, pulmonary arterial pressure between 26 and 70 mm Hg and right ventricular end-diastolic pressure between 4 and 16 mm Hg. Symptoms were lessened and right ventricular size and function improved postoperatively in these 11 patients. Unlike those with normal preoperatlve right ventricular wall motion, however, only 1 of the 11 had normal postoperative right ventricular function and became asymptomatic.     

MDL 17,043: short- and long-term cardiopulmonary and clinical effects in patients with heart failure

MDL 17,043, an inotropic and vasodilator drug, is believed to have beneficial effects in patients with heart failure. Its short- and long-term hemodynamic and cardiopulmonary effects were studied in 10 patients with New York Heart Association functional class III heart failure who were maintained on digitalis and diuretic drugs. Hemodynamics at baseline study and after 24 hours of oral therapy (four doses of 6 mg/kg) showed increased cardiac output (3.9 +/- 0.7 to 6.1 +/- 1.1 liters/min, p less than 0.05), increased stroke volume (42 +/- 12 to 60 +/- 15 ml, p less than 0.05), decreased systemic vascular resistance (1,564 +/- 326 to 1,009 +/- 296 dynes X s X cm-5, p less than 0.05) but no change in pulmonary capillary wedge pressure (31 +/- 6 to 25 +/- 13 mm Hg, p = NS). Only systemic vascular resistance and arteriovenous oxygen difference were significantly decreased during exercise. When restudied after 5 weeks of therapy, neither cardiac output nor stroke volume showed a sustained increase at rest or during exercise, and effects on systemic vascular resistance and arteriovenous oxygen difference were not sustained at exercise (p = NS). Peak oxygen uptake during exercise was 8.1 +/- 2.5 ml/kg per min at baseline and was not significantly increased either acutely (9.2 +/- 2.4 ml/kg per min, p = NS) or chronically (8.9 +/- 2.2 ml/kg per min, p = NS). Problems of increased ventricular arrhythmias and diarrhea were noted after therapy was begun.(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise testing in aortic regurgitation: comparison of radionuclide left ventricular ejection fraction with exercise performance at the anaerobic threshold and peak exercise

Serial radionuclide left ventricular ejection fractions (EF) were measured during graded supine exercise in 16 control patients and 35 asymptomatic or minimally symptomatic patients with severe aortic regurgitation (AR). Simultaneous pulmonary gas exchange analysis permitted determination of the anaerobic threshold, which is the point during exercise at which lactic acid begins to accumulate in the blood. The EF and oxygen uptake were measured at rest, anaerobic threshold and peak exercise. The mean EF (±1 standard deviation) in control patients increased from 0.65 ± 0.06 at rest to 0.73 ± 0.05 at anaerobic threshold (p < 0.01). No further change in EF occurred between anaerobic threshold and peak exercise (0.73 ± 0.09). Peak oxygen uptake in control patients was 20 ± 4 ml/ kg/min. Patients with AR were classified into 2 groups based on a peak oxygen uptake >16 ml/ kg/min (Group I, n = 26) and < 16 ml/kg/min (Group II, n = 9). In Group I the mean oxygen uptake at the anaerobic threshold and peak exercise was similar to or greater than that in control patients, whereas in Group II patients it was less than in control pa- tients. In Group I, the mean rest EF (0.62 ± 0.07) was similar to that in control patients; there was no change at the anaerobic threshold (0.61 ± 0.10), and then it decreased at peak exercise (0.57 ± 0.12, p < 0.05). In Group II, the mean rest EF (0.44 ± 0.12) was below that in control patients (p < 0.01); there was a decrease at the anaerobic threshold (0.35 ± 0.10, p < 0.01), and then it decreased further at peak exercise (0.30 ±0 0.09, p < 0.05). The anaerobic threshold and peak oxygen uptake reflect rest and exercise left ventricular EF in AR and may provide an additional approach of assessing cardiac performance in these patients. Exercise-induced changes in left ventricular EF should be based on the changes occurring before the anaerobic threshold, because changes between anaerobic threshold and peak exercise are of uncertain diagnostic value.     

Mitral valve replacement for isolated mitral regurgitation: Analysis of clinical course and late postoperative left ventricular ejection fraction

One hundred five patients underwent mitral valve replacement for relief of isolated mitral regurgitation between 1974 and 1979. There were 4 in-hospital deaths (4 percent) and 12 late deaths giving an 82 percent predicted 5 year survival rate. An age of 60 years or more at the time of surgery and a preoperative left ventricular ejection fraction of less than 0.40 were the only variables that correlated with decreased survival at 3 to 5 years after operation (p <0.05). Postoperatively, 87 (98 percent) of 89 long-term survivors were in New York Heart Association functional class I or II (68 in class I and 19 in class II). Survival did not differ between patients with porcine versus mechanical valve replacement, but patients with a mechanical valve had a greater incidence of postoperative cerebrovascular accident ($\text{8.6}\text{100}$ patient years) than did patients with a porcine valve (2.8/100 patient years) (p <0.002). Ejection fraction at rest was determined with multigated cardiac imaging 12 to 75 months post-operatively in 34 of 89 long-term survivors. The mean preoperative ejection fraction was 0.62 ± 0.09 (mean ± 1 standard deviation) and the mean postoperative ejection fraction was 0.50 ± 0.15 (p <0.001). When the preoperative value was compared with the postoperative value at rest the ejection fraction increased by 0.10 or more in 1 patient (3 percent), remained within ±0.09 of the preoperative value in 12 patients (35 percent) and decreased by 0.10 or greater in 21 patients (62 percent). Sixteen (94 percent) of 17 patients whose postoperative ejection fraction was greater than 0.50 were in functional class I postoperatively compared with 11 (65 percent) of 17 patients whose postoperative ejection fraction was 0.50 or less (p <0.05). No preoperative factor, including preoperative ejection fraction or cardiothoracic ratio, predicted the postoperative ejection fraction. A postoperative exercise ejection fraction was obtained in 29 patients, and an abnormal ejection fraction change with exercise (increase <0.05) was observed in 20 patients (69 percent). Patient age at the time of study correlated inversely with the change in ejection fraction from rest to exercise; no other variables were predictive.It is concluded that, in addition to age, only preoperative left ventricular function as measured by ejection fraction predicts survival in patients undergoing mitral valve replacement for isolated mitral regurgitation. Clinical recovery is good even though the majority of long-term survivors have a postoperative decrease in ejection fraction.     

Left ventricular regional wall motion assessment by multigated and end-diastolic, end-systolic gated radipnuclide left ventriculography

The validity and accuracy of three methods of gated cardiac blood pool imaging for the determination of regional wall motion were assessed in 124 patients undergoing contrast left ventriculography. Eighty-four patients had multigated acquisition and display, and 40 patients had end-diastolic, end-systolic gated acquisition and display in both a two frame movie format and on photographs. Both gated cardiac blood pool images and left ventriculograms were reviewed independently by three blinded observers and regional wall motion was qualitatively scored. For scoring purposes, the left ventricular wall was subdivided into anterolateral, apical, inferior, septal, apical-inferior and posterior segments. Segmental motion was graded on a five point grading scale as normal, mildly hypokinetic, moderately to severely hypokinetic, akinetic or dyskinetic. The graded scores for regional wall motion for each of the three observers were averaged and then compared. Regional wall motion scores for the gated blood pool study agreed within ± 1 grade with scores for contrast ventriculography in 338 of 402 segments (84 percent) studied with multigated acquisition and display, in 97 of 117 segments (83 percent) for the end-diastolic, end-systolic gated acquisition with motion display and in 99 of 117 segments (83 percent) for the end-diastolic, end-systolic gated acquisition with photographic display. The multigated display was least accurate in scoring of the apical segment, the end-diastolic, end-systolic gated movie display in scoring of the inferior segment and the end-diastolic, end-systolic gated photographic display in scoring of the apical and septal segments.

Scoring based on multigated blood pool images had a significantly greater percent agreement with results of contrast ventriculography when segments were normal on contrast ventriculography (88 percent) than when they were abnormal (79 percent) (p <0.05). However, analysis of receiver operating characteristics demonstrated similar levels of diagnostic accuracy for the three radionuclide blood pool imaging techniques in predicting abnormal wall motion on contrast ventriculography. Multi-gated cardiae blood pool imaging is a valid and accurate noninvasive means of detecting left ventricular regional wall motion abnormalities. End-diastolic, end-systolic gated blood pool imaging can be reliably used for regional wall motion determination when the equipment necessary for multigated acquisition is not available.