Derek Marpole

Regional contraction patterns in the normal and ischemic left ventricle in man

Abstract An angiographic method is introduced that permits detection and quantification of regional disorders of ventricular wall motion in man. The left ventricle is visualized as a muscular cone suspended freely from the atrioventricular ring. This ring, outlined partially by a coronary sinus catheter, serves as a fixed plane of reference for the motion of endocardial segments during systole. Regional motion of the left ventricle is analyzed by plotting the displacement of the apex and 6 hemiaxes during 4 sequential phases of systole. The nonischemic left ventricle (6 patients) revealed synchronous and symmetrical shortening of all segments. The middle and apical hemiaxes of the posterior wall shortened to a greater extent (62 and 70 percent, respectively) than the anterior wall segments (40 to 45 percent), and there was a slight angular displacement (5 °) of the apex toward the anterior wall. Of the ischemic hearts, 6 with predominant right coronary arterial lesions demonstrated posterior akinesis and dyskinesis during early systole and an exaggerated shortening, particularly in the posteroapical segment, during late systole. These findings were associated with a significant apical displacement (23 °) toward the wall opposite the ischemic zone. Six patients with major occlusive disease of the left anterior descending artery showed the same abnormal segmental pattern in an opposite direction. The study provides a simple technique for examining and quantitating localized disorders of wall motion, and the data indicate an association between the sites of major coronary occlusions and characteristic patterns of regional contraction.

Blood Flow and Tissue Space of the Left Coronary Artery in Man

Using a constant infusion of two indicators, T-1824 bound to albumin and tritiated water, flow and transit time were measured in the left coronary system of intact man. Indicators were infused for 6 minutes into the left coronary artery with sampling from the coronary sinus in a region that drained exclusively the inflow of the left coronary artery and from the brachial artery for recirculation. The degree of heterogeneity of myocardial perfusion could be defined by the time required for the curve to reach a plateau. A correlation coefficient of 0.966 was found between the two indicator-measured blood flows. The average myocardial hematocrit was calculated and found to be similar to the arterial. In the presence of myocardial disease, total flow of the left coronary artery was increased. When this was divided by tissue volume, the blood flow per unit volume of tissue was decreased in the presence of the idiopathic cardiomyopathy.

Clinical Outcomes After Inferior Myocardial Infarction

We studied the clinical outcomes of 46 patients followed prospectively for the initial 6 months after inferior infarction. Twenty-one patients (Group A) had no anterior ST depression (V2 to V4) present during the acute phase of the inferior infarction, whereas 25 patients (Group B) had such findings transiently. Although the clinical course during hospitalization was similar in the two groups, that after discharge differed. Only one of 21 patients in Group A had exertional angina and none had rest angina during follow-up; no infarcts or deaths occurred. In contrast, 15 patients in Group B had exertional angina; 12 also had rest pain (p less than 0.001, exact probability test). Two patients had reinfarction, one of whom died, and one sudden death also occurred. Of 15 patients in Group B who had cardiac catheterization, only eight had significant lesions in the anterior vessels, whereas seven did not; six of the seven patients became asymptomatic during follow-up without surgical therapy. Thus, electrocardiograms taken during the early phases of inferior myocardial infarction may be a valuable tool to recognize patients likely to have further ischemic symptoms during the early follow-up period.

Ventricular Aneurysm: False or True? An Important Distinction

A case of ventricular false aneurysm withe the typical clinical, radiological, electrocardiographic, and angiographic features of this entity is presented. The distinction between false ventricular aneurysm and true aneurysm is discussed. This distinction is important because of the propensity of false aneurysms to rupture. An early diastolic murmur was present prior to, but not after, resection of the aneurysmal sac. A theory as to the origin of this murmur is offered.

Interventricular delay in severe aortic stenosis recognized by gated radionuclear blood pool scanning

Twenty-four patients referred for cardiac catheterization for suspected aortic stenosis were investigated by equilibrium gated blood pool study. From the time-activity curves, end systole for each ventricle was determined and the delay between the two was calculated. The patients were divided into three groups according to their calculated aortic valve area. The mean delay in a control group of 20 normal subjects was 6 +/- 13 msec (mean +/- standard deviation). In group I (aortic valve area greater than 0.75 cm2) the delay was 16 +/- 25 msec (p = NS compared to controls); in group II (aortic valve area 0.5 to 0.75 cm2) the delay was 28 +/- 27 msec (p less than 0.01); and in group III (aortic valve area less than 0.5 cm2) the delay was 60 +/- 28 msec (p less than 0.001). Ten patients were restudied after valve replacement; their mean delay decreased markedly from 48 +/- 19 to 5 +/- 26 msec (p less than 0.001). Thus, this method appears to identify patients with severe aortic stenosis and may therefore be a useful adjunct to the noninvasive assessment of this disorder both before and after surgery.

Early diastolic posterior aortic root slope, a clinical guide to the severity of mitral stenosis

This report tests the hypothesis that, in early diastole, motion of the anterior left atrial wall corresponds to the motion that can be observed in the contiguous posterior wall of the aortic root. To test this hypothesis, we examined the effects of mitral stenosis, exercise in normals, exercise induced left ventricular ischemia, left ventricular hypertrophy and left ventricular dysfunction on this slope. Each altered early diastolic atrioventricular interaction as predicted and therefore, the early diastolic motion of the anterior left atrial wall does appear to be mirrored by the early diastolic slope of the posterior wall of the aortic root. Consequently, if interpreted in the clinical context, measurement of early diastolic slope of the posterior wall of the aortic root may serve as a useful guide to separate patients with severe from those with mild mitral stenosis.

Differences between the effects of practolol and propranolol on the diastolic properties of the left ventricle

To elucidate the mechanism by which left ventricular end diastolic pressure (LVEDP) is reduced by practolol, ventricular volumes, hemodynamics, and diastolic elastic stiffness were determined before and 10 min after intravenous practolol (400 µg/kg) in 12 patients. Heart rate decreased in all patients after practolol (avg., −9/min, p < 0.02). There was an insignificant increase in stroke work index and decrease in cardiac index attributable to the fall in rate. Practolol did not change end diastolic volume or ejection fraction, but the average LVEDP fell from 21 to 15 mm Hg (p < 0.01) which was sustained even with atrial pacing to prepractolol heart rates. Diastolic elastic stiffness was also reduced after practolol (0.665 to 0.593, p < 0.0025). The data indicate that practolol exerts a negative chronotropic effect on the intact heart and, in contrast to other beta blockers such as propranolol, appears to decrease diastolic stiffness in the left ventricle.