James L. Weiss

Regional cardiac dilatation after acute myocardial infarction. Recognition by two-dimensional echocardiography

To assess the early topographic changes after acute transmural myocardial infarction, we studied 28 patients during the first two weeks after infarction by serial two-dimensional echocardiography. Regional end-diastolic segment lengths and wall thicknesses for anterior and posterior left ventricular walls were calculated. Eight patients showed infarct expansion, with disproportionate dilatation and transmural thinning in the infarcted zone, that was significantly different (P less than 0.005) from changes in non-infarcted regions. This regional expansion led to an overall left ventricular dilatation in these eight patients of 25 per cent compared to 5 per cent in the 20 patients without infarct expansion. Although the eight patients with regional expansion did not have significantly higher peak creatine kinase or Killip classification, they had a significantly greater eight-week mortality (four of eight versus none of 20, P less than 0.004). Thus, regional cardiac dilatation may be an early, lethal consequence of transmural infarcts, and appears to be an important mechanism of acute cardiac dilatation after myocardial infarction.

Noninvasive quantification of left ventricular rotational deformation in normal humans using magnetic resonance imaging myocardial tagging.

It has been postulated that rotation of the left ventricular apex with respect to the base is a component of normal systolic function in humans, but it has been difficult to measure it noninvasively. Tagging is a new magnetic resonance imaging technique that labels specific areas of myocardium by selective radio-frequency excitation of narrow planes orthogonal to the imaging plane before acquiring an image. Tags appear as black lines and persist in myocardium for 400-500 msec and, if applied at end diastole, will move with the myocardium through systole. Tagging was used to noninvasively quantify left ventricular torsion and circumferential-longitudinal shear (shearCL) in humans. Eight normal volunteers, aged 24-38 years, were imaged in a 0.38-T iron-core resistive magnet. Five short-axis left ventricular images, positioned to encompass the entire left ventricle (LV), were obtained separately at end systole. Four equiangular radial tags had been applied at end diastole, intersecting the myocardium at eight locations. We calculated the difference in angular displacement of each epicardial and endocardial tag point (a tag point being where the tag crossed the epicardium or endocardium) at end systole from the systolic position of the corresponding tag point on the basal plane. This value was called the torsion angle. From this, shearCL, the angle inscribed on the epicardial or endocardial surface between the systolic tag position, the corresponding basal tag position, and its projection onto the slice of interest could be calculated at 32 points in the left ventricular wall.(ABSTRACT TRUNCATED AT 250 WORDS)

The Effects of Antihypertensive Therapy on Left Ventricular Mass in Elderly Patients

Left ventricular mass sometimes decreases during treatment of hypertension, but this response is inconsistent and its effects on left ventricular function are unknown. In a six-month randomized trial, we studied the ability of verapamil and atenolol to reduce left ventricular mass in 42 elderly patients with hypertension and the effects of this reduction in mass on cardiac function. The mean blood pressure (+/- SE) decreased in both the group that received verapamil (from 171.4 +/- 3.2/93.0 +/- 2.5 mm Hg to 142.9 +/- 2.8/79.0 +/- 2.0 mm Hg) and the group that received atenolol (from 179.6 +/- 4.6/98.5 +/- 2.4 mm Hg to 148.1 +/- 3.3/83.4 +/- 1.2 mm Hg), but the atenolol-treated patients more frequently required the addition of chlorthalidone to achieve blood-pressure reduction (P less than 0.01). Verapamil resulted in a reduction in the left-ventricular-mass index from 104 +/- 5 g per square meter of body-surface area to 85 +/- 5 g per square meter (P less than 0.01). Atenolol did not produce a reduction in the left-ventricular-mass index (109 +/- 9 g per square meter before treatment vs. 112 +/- 10 g per square meter after treatment). Two weeks after the withdrawal of antihypertensive therapy, blood pressure returned to pretreatment values. Nevertheless, in patients whose left ventricular mass had decreased, two measures of diastolic filling, the peak diastolic filling rate to the peak ejection rate, were significantly higher than before treatment (2.42 +/- 0.2 vs. 3.31 +/- 0.4 [P less than 0.05] and 0.61 +/- 0.03 to 0.85 +/- 0.05 [P less than 0.05], respectively). Diastolic filling was unchanged in the group that had no reduction in left ventricular mass. Cardiac output and the ejection fraction at rest and during mild exercise were unchanged in both groups as compared with baseline values. We conclude that left ventricular mass can be reduced in elderly patients with hypertension and mild ventricular hypertrophy who receive antihypertensive therapy. Reduction occurs more frequently with verapamil than with atenolol therapy, increases diastolic filling, and does not impair systolic function.

Early dilation of the infarcted segment in acute transmural myocardial infarction: role of infarct expansion in acute left ventricular enlargement.

Left ventricular enlargement after myocardial infarction is a poor prognostic sign, the mechanism of which has not been well defined. Early left ventricular dilation may be due to the Frank-Starling effect, which results in an increase in the length of uninfarcted segments in response to a reduction in contractile muscle mass. In contrast to this adaptive physiologic mechanism, left ventricular dilation may alternatively be caused by a pathologic process that stretches and thins the infarcted myocardial segment (that is, infarct expansion). To determine the relative contributions of these two mechanisms to left ventricular dilation after an initial transmural anterior myocardial infarction, two-dimensional echocardiograms were obtained from 27 patients within 72 hours of the onset of symptoms of myocardial infarction and from 13 healthy control subjects. In the minor-axis echocardiographic view at the level of the papillary muscles, anterior and posterior endocardial segment lengths at end-diastole were measured with a microprocessor-based graphic system. The papillary muscles were used as internal landmarks to demarcate the anterior and posterior segments. Anterior (infarcted) segment length in patients with myocardial infarction was 11.6 +/- 2.2 cm (mean +/- SD), whereas in control subjects, anterior segment length was 8.6 +/- 1.2 cm (p less than 0.001). Posterior (uninfarcted) segment length in the patients was not significantly different from posterior segment length in the control subjects (5.4 +/- 1.2 versus 5.3 +/- 1.0 cm, respectively). Measurable left ventricular dilation during the first 3 days after transmural anterior myocardial infarction is due to dilation of the infarcted segment and not of the normal uninfarcted segment.(ABSTRACT TRUNCATED AT 250 WORDS)

Immediate improvement of dysfunctional myocardial segments after coronary revascularization: Detection by intraoperative transesophageal echocardiography

To ascertain the immediate effects of coronary artery bypass grafting on regional myocardial function, intraoperative transesophageal two-dimensional echocardiograms were obtained in 20 patients using a 3.5 MHz phased array transducer at the tip of a flexible gastroscope. Cross-sectional images of the left ventricle were obtained at multiple levels before skin incision and were repeated serially before and immediately after cardiopulmonary bypass. Using a computer-aided contouring system, percent systolic wall thickening was determined for eight anatomic segments in each patient at similar loading conditions (four each at mitral and papillary muscle levels). Of the 152 segments analyzed, systolic wall thickening improved from a prerevascularization mean value (+/- SEM) of 42.7 +/- 2.9% to a postrevascularization mean value of 51.6 +/- 2.6% (p less than 0.001). Thickening improved most in those segments with the worst preoperative function (p less than 0.001). Chest wall echocardiograms obtained 8.4 +/- 2.3 days after operation showed no deterioration or further improvement in segmental motion compared with transesophageal echocardiograms obtained after revascularization. Thus: regional myocardial function frequently improves immediately after bypass grafting, with increases in regional thickening being most marked in those segments demonstrating the most severe preoperative dysfunction, and this improvement appears to be sustained; and in some patients, chronic subclinical ischemic dysfunction is present which can be improved by revascularization.

Reversible Cold-Induced Abnormalities in Myocardial Perfusion and Function in Systemic Sclerosis

The effects of peripheral cold exposure on myocardial perfusion and function were studied in 13 patients with scleroderma without clinically evident myocardial disease. Ten patients had at least one transient, cold-induced, myocardial perfusion defect visualized by thallium-201 scintigraphy, and 12 had reversible, cold-induced, segmental left ventricular hypokinesis by two-dimensional echocardiography. The 10 patients with transient perfusion defects all had anatomically corresponding ventricular wall motion abnormalities. No one in either of two control groups (9 normal volunteers and 7 patients with chest pain and normal coronary arteriograms) had cold-induced abnormalities. This study is the first to show the simultaneous occurrence of cold-induced abnormalities in myocardial perfusion and function in patients with scleroderma. The results suggest that cold exposure in such patients may elicit transient reflex coronary vasoconstriction resulting in reversible myocardial ischemia and dysfunction. Chronic recurrent episodes of coronary spasm may lead to focal myocardial fibrosis.

Value of intraoperative left ventricular microbubbles detected by transesophageal two-dimensional echocardiography in predicting neurologic outcome after cardiac operations

To determine whether the presence or absence of left ventricular (LV) intracavitary microbubbles during cardiac surgery predicts neurologic sequelae, 82 patients undergoing cardiac surgery were studied using transesophageal 2-dimensional (2-D) echocardiography. Cross-sectional images were recorded just before and immediately after cardiopulmonary bypass and stop frames were reviewed for the presence of microbubbles, rated as: 0 = absent, 1 = fewer than 5/frame, 2 = 10 to 25/frame, 3 = too numerous to count. Microbubbles were detected after cardiopulmonary bypass in 34 patients (41%) and found more often in valvular or other intracardiac manipulations than in coronary revascularization, 30 of 40 vs 4 of 42, respectively (p less than 0.001). When grade 2 or 3 microbubbles were identified (22 of 34 patients), mechanical attempts to eradicate them were not successful. Postoperative follow-up in all patients revealed no new focal neurologic deficits. Prolonged encephalopathy (confusional state more than 72 hours) occurred in 4 of 48 patients with no detectable microbubbles and in 3 of 34 patients with microbubbles (difference not significant). Thus, intracavitary left ventricular microbubbles are often detected during cardiac operations, particularly during valve replacement, but are not predictive of postoperative neurologic complications. This is true even if microbubbles are densely concentrated; attempts to eradicate microbubbles are unsuccessful and may be unnecessary.

High prevalence of target organ damage in young, African American inner-city men with hypertension

Young, urban, African American men are at particularly high risk of hypertension and its cardiovascular complications. Left ventricular hypertrophy and renal dysfunction are manifestations of target organ damage from hypertension that predict adverse cardiovascular events. The subjects of this study were 309 African American men, age 18–54 years, with hypertension, residing in inner‐city Baltimore. Echocardiograms, electrocardiograms, serum creatinine, and the urinary albumin‐creatinine ratio were obtained to evaluate hypertensive target organ damage. Fifty‐three percent of the men reported use of antihypertensive medications, of whom 80% were on monotherapy. Calcium channel blockers were used most frequently. The mean echocardiographic left ventricular mass was 211±68 g, with a prevalence of echocardiographic left ventricular hypertrophy of 30%. There were 14 men (5%) with extremely high left ventricular mass, >350 grams. Left ventricular systolic dysfunction was seen in 9% of the men with uncontrolled hypertension, and none of the men with controlled hypertension (p=0.02). Renal dysfunction was found in 12% of the subjects, and microalbuminuria or gross proteinuria in 34%. The authors conclude that there is a high prevalence of cardiac and renal abnormalities in inner‐city African American men with hypertension, especially in men on antihypertensive therapy with uncontrolled hypertension. It is imperative that cost‐effective medications and culturally acceptable health care delivery programs be developed, tested, and integrated into health systems, with strategies specifically relevant to this high‐risk population, to decrease the largely preventable morbidity and mortality associated with hypertension.

Leftward septal displacement during right ventricular loading in man: Demonstration by two-dimensional echo

Little direct evidence in man indicates that acute right ventricular loading alters left ventricular configuration. We used the Mueller maneuver (forced inspiration against a closed airway) to increase right ventricular loading and evaluated septal shape and right and left ventricular size in nine normal, semisupine men with phased–array, two–dimensional echocardiography. End–systolic and end–diastolic frames in cross–sectional and longitudinal views of the ventricles were recorded at rest and at various phases during the Mueller period (peak inspiratory effort of 40–60 mm Hg negative pressure). Acute leftward displacement of the septum at end–diastole on cross section during the maximal early Mueller period (first two or three beats after the onset of Mueller maneuver) was evidenced by a substantial increase in the radius of curvature of the septal segment (3.72 ± 0.25 cm vs control, 2.49 ± 0.12 cm,p < 0.001). This leftward septal displacement persisted not only during end–diastole, but also during end–systole (3.58 ± 0.45 vs 2.04 ± 0.16 cm;p < 0.01). The septal radius of curvature did not differ from the radius of curvature of the remainder of the left ventricle at rest for systole or diastole (1.94 ± 0.11 and 2.48 ± 0.09 cm, respectively), but differed markedly during the early Mueller phase in both systole (3.58 + 0.45 vs 1.9 ± 0.07 cm; p < 0.005) and diastole (3.72 ± 0.25 vs 2.36 ± 0.07 cm; p < 0.001). Simultaneously, left ventricular end–diastolic cavity areas decreased from control to the early Mueller phase on cross–sectional view from 19.14 ± 1.08 cm2 to 15.73 ± 0.65 cm2 (p < 0.005), and longitudinal view from 29.83 ± 2.08 to 20.74 1.46 cm2; p < 0.001. A significant decrease in endsystolic cavity area was also noted in this view (19.72 i 2.0 to 15.23 ± 1.98 cm2;p < 0.05). Right ventricular end–diastolic diameter increased from control to the early Mueller phase in the cross–sectional view (1.06 ± 0.14 to 1.31 ± 0.17 cm;p < 0.02), as well as in the longitudinal view (1.14 ± 0.23 to 1.80 ± 0.43 cm; p < 0.05). A decrease in left ventricular volume with maintenance of constant shape should result in a shortened radius of curvature for all portions of the ventricle, so the increase in septal radius of curvature in the face of an overall decrease in left ventricular size indicates that right ventricular loading alters left ventricular shape by flattening the septum. This septal flattening persists during systole. Thus, changed septal shape may be an important mechanism of, and evidence for, ventricular interdependence in normal man.

Clinical recognition of giant left ventricular aneurysm

The noninvasive diagnosis of left ventricular aneurysm has markedly improved with gated blood pool scintigraphy. However, in patients with giant anterior ventricular aneurysms, the gated blood pool scintigram performed in two standard views (anterior and 40 degree left anterior oblique) may incorrectly suggest ischemic cardiomyopathy. We retrospectively identified five patients who underwent resection of a ventricular aneurysm over a 2 1/2 year period and who had preoperative scintigraphic studies that appeared to show severe diffuse left ventricular dysfunction. contrast ventriculography demonstrated preserved wall motion in septal, inferior and lateral segments not seen by gated blood pool scintigraphy and showed extraordinarily large anterior aneurysms. M-mode or two-dimensional echocardiograms showed intact posterior wall function in all patients, suggesting severe regional myocardial disease rather than global dysfunction. Two-dimensional echocardiography showed additional segments with preserved function as well as discrete aneurysms in all patients. We conclude that gated blood pool scintigraphy, when performed in two standard views, may fail to correctly diagnose some patients with very large anterior wall aneurysms. M-mode echocardiography, two-dimensional echocardiography and additional scintigraphic views that visualize the posterior portions of the left ventricle improve noninvasive diagnosis of patients with resectable giant left ventricular aneurysms.