John F. Phillips

Correlation of computer-quantitated treadmill exercise electrocardiogram with arteriographic location of coronary artery disease☆

Abstract Graded treadmill exercise testing and coronary cinearteriographic studies were carried out on 86 patients with angina pectoris. At rest, all patients demonstrated a normal S-T segment on the modified bipolar lead V 5 recording used. The computer-quantitated S-T segment response to exercise was correlated with the location and extent of obstructive coronary artery disease. The coronary cineartertograms were reviewed by 3 physicians and stenosis of 75 percent or greater was considered significant. All patients showed at least this degree of stenosis in 1 or more major coronary arteries, and 83 of 86 exhibited 90 percent or greater stenosis in at least 1 artery. Thirty-one patients had stenosis in a single artery, 43 had stenosis in 2 arteries and 12 had significant lesions in all 3 major arteries. In 70 of the 86 (82 percent) patients, a positive S-T segment response developed during or immediately after exercise. In 12 of the 16 with a negative response, disease was limited to a single artery. In 11 of the 12 the disease was restricted to the right coronary or left circumflex arteries. Of the 12 patients with an isolated stenosis of the left anterior descending artery, 11 (92 percent) had a positive S-T segment response. Of 55 patients with 2- or 3-vessel disease, 51 (93 percent) demonstrated a positive S-T response. Graded treadmill exercise testing in 80 patients with chest pain, normal coronary art eriograms and normal left ventricular function revealed 4 (5 percent) with a false positive S-T segment response. The possible mechanisms underlying the high incidence of false negative exercise electrocardiographic tests in patients with disease isolated to the right coronary or left circumflex artery are discussed.

Detection of Left Ventricular Asynergy by Echocardiography

The purpose of this study was to determnie if echocardiography could detect left ventricular asynergy. Forty-eight patients underwent selective coronary arteriography and cineventriculography for the evaluation of chest pain. Four patients were studied twice: three before and after myocardial revascularization and one before and after an intervening myocardial infarction. Echocardiographic M-mode scans were registered on a strip chart as the left ventricle was scanned with an ultrasonic beam from the aortic root to the region of the posterior papillary muscle approximately 18 hrs prior to the catheterization studies.Ten of the forty-eight patients had no evidence of coronary artery disease. All ten patients had normal ventriculograms in right anterior oblique projection and their echocardiographic scans showed all areas of the left ventricular posterior wall endocardium to move anteriorly 0.9-1.4 cm (mean 1.2 cm) and all parts of the left side of the interventricular septum to move posteriorly 0.3-0.8 cm (mean 0.5 cm) during systole. The 38 patients with significant obstructive coronary artery disease had a total of 42 studies; 25 of these studies showed left ventricular asynergy on the ventriculogram taken in right anterior oblique. The echocardiograms associated with all but one of these studies demonstrating left ventricular asynergy had abnormal motion of some part of the interventricular septum and/or left ventricular posterior wall. Seventeen studies in patients with significant coronary artery disease did not exhibit left ventricular asynergy on the ventriculogram but eight of these studies were associated with distinctly abnormal echocardiograms.None of the ten patients with significant coronary artery disease and normal echocardiograms had evidence of transmural infarction on their electrocardiograms. Echocardiographic abnormalities correlated with the anatomic area predicted by the myocardial infarction pattern on the electrocardiogram in 18 of 20 patients.All patients demonstrating abnormal echographic interventricular septal motion had a significant obstructive lesion in the left anterior descending coronary artery. In the absence of significant involvement of the left anterior descending coronary artery, echographically recorded interventricular septal motion was invariably normal. On the other hand, eight patients had significant obstruction in their left anterior descending coronary artery and their echographic interventricular septal motion was normal.The results of this correlative study indicate that M-mode echocardiographic scans can detect left ventricular asynergy and may possibly predict regional myocardial involvement in coronary artery disease.

Exercise-induced U-wave inversion as a marker of stenosis of the left anterior descending coronary artery.

The prevalence and cineangiographic correlates of exercise-induced inversion of U waves were studied in 248 patients. Exercise-induced U-wave inversion was observed in 36 patients (15%), of whom 35 had > 75% stenosis in one or more of the major coronary arteries. The proximal left anterior descending or left main coronary artery was involved in 33 of these patients, including 24 patients with no electrocardiographic evidence of anterior myocardial infarction. Exercise-induced U-wave inversion was observed in the absence of an abnormal ST-segment response in eight of the 166 patients (4.8%) with coronary artery disease, and five of these patients had a normal resting 12-lead ECG. Only one of the 82 patients (1.2%) without significant coronary artery disease demonstrated exercise-induced U-wave inversion, and this patient had a primary cardiomyopathy. We conclude that exercise-induced inversion of the U-wave is highly predictive of significant coronary artery disease and, more specifically, of disease of the proximal left anterior descending coronary arter.

Incidence and significance of decreases in systolic blood pressure during graded treadmill exercise testing

Abstract The incidence of decreases in peak systolic blood pressure during treadmill exercise was investigated in 460 patients with definite or suspected coronary heart disease. All patients were studied with coronary cineangiography. Exercise was continued to one of the following end points: chest pain, 85 to 90 percent of the patients age-predicted maximal heart rate, ventricular tachycardia or a sustained decrease of 10 mm Hg or more below the peak level of systolic blood pressure. Twenty-two patients with 75 percent or greater stenosis of one or more major coronary arteries manifested a decrease in systolic pressure 10 mm Hg or more during exercise. These included 15 (17 percent) of 88 patients with three vessel, 7 (7 percent) of 101 with two vessel and 0 of 90 with single vessel disease. The decrease in pressure was reproducible in the seven patients who underwent a second exercise test before alteration of therapy; this decrease was abolished in the six patients who exercised again after coronary bypass graft surgery. A decrease in systolic pressure of 10 mm Hg or more also occurred during exercise testing in 3 of 23 patients with noncoronary organic heart disease; all 3 had an obstructive cardlomyopathy that had not been suspected clinically. Only 1 of 158 subjects with chest pain and no demonstrable heart disease had a decrease in systolic blood pressure with exercise. Declines in blood pressure were not observed during 650 maximal exercise tests performed on 560 clinically normal men. In conclusion, if one excludes subjects with cardiomyopathy or significant heart valve disease, a sustained exercise-induced decrease in peak systolic blood pressure of 10 mm Hg or more is a highly specific sign of multiple vessel coronary artery disease. This phenomenon is best explained by acute left ventricular pump failure secondary to extensive myocardial ischemia.

Coronary angiographic, echocardiographic, and electrocardiographic studies on a patient with variant angina due to coronary artery spasm

A 45-year-old Caucasian female patient with a clinical rehistory and ECGs conforming to the syndrome of variant angina as characterized by Prinzmetal is presented. ECGs recorded during spontaneous pain demonstrated ST-segment elevation and symmetrical peaking of the T-waves in the lateral precordial leads and short runs of ventricular tachycardia. Similar ECG changes were recorded during treadmill exercise- and hand-grip exercise-induced chest pain. An echocardiogram recorded during angina induced by hand-grip exercise demonstrated progressive flattening of septal motion. Multiple views of the coronary system by selective coronary cineangiography were normal with the patient at rest. Angina was then induced by hand-grip exercise and a repeat right anterior oblique view of the left coronary system revealed marked spasm of the left anterior descending artery proximal to the first septal perforator.

Coronary Collateral Circulation and Myocardial Blood Flow Reserve

This study was undertaken to assess the effect of collateral circulation on myocardial blood flow (MBF) reserve (ability to increase myocardial blood flow with a stress that increases myocardial oxygen requirements). One hundred patients had MBF measured at rest and after isoproterenol. After classification by anatomic severity of coronary artery disease (CAI), the groups were further compared by presence or absence of collateral vessels, and whether the collaterals were intercoronary or bridge collaterals. Forty patients (group A) had no coronary artery disease demonstrated by cineangiography. The increase in MBF with isoproterenol for this group was 87% (P < 0.001). Fifteen patients (group B) had CAI of 175 or greater. These patients increased MBF 73% on infusion of isoproterenol, an insignificant difference from group A. Forty-five patients (group C) had CAI of 175 or less when an index of 300 represents no occlusive disease. Those with intercoronary collateral vessels (group C1, 2) were unable to increase MBF to the same extent as patients in groups A and B did. There was no difference between this group and those without collateral vessels and the same severity of disease. Fifteen patients with CAI of 175 or less (group C3, 4) had bridge collaterals and were able to increase MBF to a greater extent than those with no collaterals or with intercoronary collateral vessels. This same group of patients, in a parallel observation, showed less S-T-segment depression on treadmill exercise than patients with intercoronary collateral vessels.The data suggest that intercoronary collateral vessels contribute insignificantly, statistically, to myocardial blood flow reserve. Bridge collaterals, however, do seem to contribute in selected patients.

Stroke volume calculated from the mitral valve echogram in patients with and without ventricular dyssynergy.

SUMMARY A formula was derived for calculating mitral valve stroke volume (MVSV) using the rate of mitral valve (MV) opening (DE slope on the MV echogram), the vertical distance between the mitral leaflet echoes early in diastole (EE), the electrocardiographic PR interval and heart rate. The formula was tested prospectively on 80 consecutive patients from whom 95 simultaneous MV echograms and either thermodilution (45) or Fick (50) cardiac outputs were obtained. Sixteen patients were normal; 54 had coronary artery disease; three had cardiomyopathy; and seven had nonrheumatic mitral regurgitation (MR). Linear regression for stroke volume was r = 0.90, SEE ± 6, and for cardiac output r = 0.83, SEE ± 0.5 liter for the 73 patients without MR. The presence or absence of ventricular dyssynergy did not alter statistical findings. MVSV consistently overestimated forward stroke volume for the seven patients with MR. This study shows that the MV echogram provides an accurate, widely applicable method for calculating MVSV.

Myocardial Blood Flow in Coronary Artery Disease Effect of Right Atrial Pacing and Nitroglycerin

Sixteen patients, 10 with significant three-vessel coronary artery disease (>50% occlusion of each vessel) and six without coronary disease, had nutrient myocardial blood flow, cardiac output, pressure time/min and arterial pressure determinations at rest, with atrial pacing and with right atrial pacing plus nitroglycerin. In the patients with coronary disease, nutrient myocardial blood decreased an average of 16% (P < 0.001) with pacing alone but increased by 22% (P < 0.001) from the pacing flows with the addition of 0.4 mg sublingual nitroglycerin at the same pacing rate. The directional changes in myocardial blood flow were unrelated to perfusion pressure or pressure work. In the patients without coronary disease, opposite effects were observed. With right atrial pacing, nutrient myocardial blood flow increased by 23% (P < 0.02). With the addition of nitroglycerin, myocardial blood flow decreased by 15% (P < 0.02). These changes were directionally related to changes in pressure-work of the heart It is suggested that the findings in this study are consistent with observations made in the experimental animal which indicate that the effect of nitroglycerin may be partly due to a redistribution of myocardial blood flow.

Atropine-lnduced cardioacceleration and myocardial blood flow in subjects with and without coronary artery disease

Abstract Thirty-five patients being studied by coronary cineangiography for diagnosis or evaluation of coronary atherosclerotic occlusive disease had myocardial blood flow determinations at rest and after intravenous administration of atropine sulfate, 1.0 mg. Myocardial blood flow was determined by a coincidence counting system and a single bolus injection of 84 rubidium chloride. In 10 patients without coronary occlusive disease, heart rate increased by 52 percent and myocardial blood flow by 48 percent ( P r = 0.888). In 14 patients with single vessel disease or partial occlusion of two vessels, myocardial blood flow increased by 44 percent and heart rate by 37 percent ( P r = 0.553). In 11 patients with two or three vessel occlusive disease, heart rate increased by 30 percent whereas myocardial blood flow increased by only 15 percent ( r = −0.172). We conclude that patients with two and three vessel involvement by atherosclerotic occlusive disease are unable to increase nutrient myocardial blood flow in response to atropine-induced Cardioacceleration to the same degree as patients without coronary disease or with less extensive disease. The observation may be of therapeutic importance because of the potential that administration of atropine may have for inducing myocardial ischemia in such patients.

The Effect of Aortocoronary Bypass Grafts on Myocardial Blood Flow Reserve and Treadmill Exercise Tolerance

Twenty-five patients had myocardial blood flow reserve determinations (percentage increase in myocardial blood flow with stress), treadmill exercise tests and coronary and bypass cineangiography pre- and postaortocoronary bypass surgery. Twenty of the patients had the postoperative studies performed three months after operation, three at two months and two at five and six months, respectively.Eleven of the 25 patients had all significant coronary artery obstructions (75% or greater) bypassed and all grafts were open at the time of restudy. Preoperatively, blood flow reserve had been abnormal in nine and all had positive treadmill tests. Postoperatively, all eleven patients had normal myocardial blood flow response to stress and treadmill tests were negative in ten (one patient was not restudied on the treadmill).In six patients, no patent grafts could be demonstrated. These patients continued to show abnormal blood flow reserve and positive treadmill studies.Eight of the 25 patients had partial revascularization in that some grafts were open, some closed, and some significantly occlusive lesions were not bypassed. Four of these eight patients had normal flow and treadmill studies and the remainder continued to have an abnormal response to one or both of the measurements.The relationship between treadmill exercise response, myocardial blood flow reserve, and graft patency was significant at the 0.005 level for patients with all grafts open or closed. No significant correlation was obtained between any of the measurements in those patients with partial revascularization.The data indicate that successful aortocoronary bypass grafting provides myocardial revascularization as reflected in a return to normal of the myocardial blood flow reserve and response to treadmill stress testing.