John Idoine

Ejection fraction image: A noninvasive index of regional left ventricular wall motion

Abstract The clinical value of the ejection fraction image, a computerized radionuclide measurement of regional left ventricular wall motion, was assessed in 34 patients. From gated modified left anterior oblique images of the cardiac blood pool, regional ejection fraction images were created. Left ventricular wall motion was classified with ejection fraction imaging as normal, hypokinetic or akinetic in each of three left ventricular regions. Wall motion was similarly characterized with regional analysis (segmental axis shortening, extent of akinetic segments) of contrast angiograms. Results of ejection fraction imaging were assessed in comparison with angiographic analyses. Seventeen patients had asynergy on contrast ventriculography; the other 17 had normal wall motion. There was agreement between the contrast and radionuclide ventriculograms as to presence of asynergy in 33 of 34 patients. In 92 of 102 (90 percent) left ventricular regions evaluated with both contrast and radionuclide methods, the ejection fraction image and contrast angiogram were in agreement regarding presence or absence of wall motion abnormalities. Of 43 abnormal angiographic wall motion descriptions in 35 ventricular regions (8 regions contained both hypokinetic and akinetic segments), 35 (81 percent) were similarly identified with the ejection fraction image. These results suggest that the ejection fraction image is a sensitive indicator of regional left ventricular wall motion.

Effect of Sublingually Administered Nitroglycerin on Regional Myocardial Blood Flow in Patients With Coronary Artery Disease

The effect of sublingually administered nitroglycerin on regional myocardial specific blood flow (in ml/min per 100 g tissue) was evaluated with a xenon-133 washout technique in 31 patients in a resting nonstressed state. Eight patients had normal coronary arteriograms (Group 1), 12 had coronary artery disease without collateral vessels (Group 2) and 11 had coronary artery disease with collateral vessels (Group 3). Although nitroglycerin caused a similar decrease in mean arterial blood pressure and blood pressure-heart rate product in all three groups, the decrease in regional myocardial blood flow was significantly less in Group 3 (-8+/-6% [mean+/-standard error of the mean]) than in Group 1 (-31+/-5%), P less than 0.05); an intermediary decrease occurred in Group 2 (-23+/-5%). Within Group 3, there was a mean increase in regional myocardial blood flow after nitroglycerin in the five patients whose collateral vessels were of a higher angiographic grade and arose from non-stenosed coronary arteries, whereas a reduction was observed in the six patients with none or only one of these findings (+10+/-7% versus -23+/-3%, P less than 0.001). This study suggests that even in the resting state, in some patients with coronary artery disease enhancement of regional myocardial blood flow can occur after sublingual administration of nitroglycerin and is probably mediated through well functioning collateral vessels. It is possible that the drugs effects on both the coronary and systemic circulation may relieve angina in some patients with coronary artery disease.

Disruption in the temporal sequence of regional ventricular contraction. I. Characteristics and incidence in coronary artery disease.

While spatial asynergy at end-systole has been well characterized in patients with coronary artery disease, assessment of regional asynchrony has been hampered by technical constraints. We developed a computer-assisted method for analyzing regional asynchrony from the equilibrium (ECG-gated) radionuclide ventriculogram. Twenty patients with normal contrast left ventriculograms (nine with a normal coronary arteriogram [group 1] and 11 with coronary artery disease [group 2]) and 20 patients with asynergy during contrast ventriculography (group 3) were studied. The earliest evidence of regional asynchrony occurred in early systole. Regional ejection fraction at one-third systole was 0.32 i 0.02 (mean + SEM) in group 1, 0.22 4 0.01 in group 2 (p < 0.001) and 0.12 ± 0.01 in asynergic regions in group 3 patients (p < 0.001). In group 3, severe forms of regional asynchrony appeared in both early systole and early diastole: five patients (25%) had early systolic paradox, 13 (65%) had regional prolongation of peak ejection fraction and 16 (80%) had reduced percent peak ejection fraction at global end-systole. It appears, therefore, that there is progressively increasing regional asynchrony in patients with increasing severity of coronary artery disease.

Measuring Regional Myocardial Blood Flow with 133Xe and the Anger Camera

Regional myocardial blood flow was measured using the inert gas washout technique and the Anger scintillation camera following injection of 133Xe into the coronary artery. By applying compartmental analysis to 30-minute washout curves, three compartments were delineated, representing blood flow to fat (IIIF) and myocardium (IM and IIM). Regional heterogeneity of flow was a highly sensitive index of coronary artery disease. Functional images delineated areas of altered perfusion better than quadrantic flow values. Gamma camera images of initial xenon distribution identified patients with severely altered flow.

Regional myocardial blood flow during hyperemia induced by contrast agent in patients with coronary artery disease

Regional myocardial specific blood flow (regional specific flow) was measured at rest and during contrast hyperemia after the intracoronary injection of xenon-133. The changes in regional specific flow were transient, resulting in some compromise in one of the underlying restraints of the inert gas washout method, namely, the presence of a steady state. Therefore, to determine the clinical utility of this technique, regional specific flow values obtained with this method were correlated with the presence and severity of coronary artery disease as assessed from the coronary arteriogram and left ventriculogram. Regional specific flow during contrast hyperemia was 186+/- 11 (mean +/- 1 standard error of the mean) ml/min per 100 g in control patients and 115+/-5 in patients with coronary artery disease. There was an inverse relation between regional specific flow during contrast hyperemia and the percent coronary stenosis when the stenosis was 40 percent or greater (r = 0.70, P less than 0.001). Regional specific flow was significantly less in patients with asynergy (77 +/- 10 ml/min per 100 g) than in patients with normal ventricular function (105 +/- 5) distal to coronary stenoses of greater than 75 percent. Thus regional specific flow measured during contrast hyperemia using the xenon washout technique and the Anger camera differentiated patients with normal coronary arteriograms from those with coronary artery disease. With this technique, good correlation was shown between regional specific flow and the percent coronary stenosis and presence of ventricular wall abnormalities. The information obtained with this method may provide prognostic information concerning suitability for surgical intervention.

Regional left ventricular function in acute myocardial infarction: Evaluation with quantitative radionuclide ventriculography

Regional and global left ventricular performance was noninvasively assessed with quantitative gated equilibrium radionuclide ventriculography in 43 patients an average of 40 hours after the onset of a first acute transmural myocardial infarction. In all 16 patients with anterior infarction, regional ejection fraction, a quantitative measure of regional left ventricular performance, was uniformly depressed in the infarcted zone. In patients with inferior infarction the abnormalities of regional performance were less severe. Fourteen of 20 patients (70 percent) with inferior infarction had depressed performance in the infarcted zone. Function in noninfarcted zones was abnormal in only 6 of the 20 patients (30 percent) with inferior infarction, but it was abnormal in 11 of the 16 patients (69 percent) with anterior infarction, particularly in those with severe pump failure. As a consequence, global left ventricular ejection fraction was significantly lower in patients with anterior than in those with inferior infarction (mean +/- standard error of the mean 31 +/- 3 percent versus 51 +/- 3 percent, less than 0.005). Prognosis and clinical functional class were related to performance not only in infarcted zones, but also in noninfarcted zones as assessed with electrocardiography. It is concluded that depressed function in apparently noninfarcted left ventricular zones contributes significantly to left ventricular dysfunction after acute myocardial infarction, particularly in patients with anterior infarction.

Effect of the cold pressor test on regional myocardial blood flow in patients with coronary artery disease

The cold pressor test is a potent alpha-adrenergic vasoconstrictor stimulus, but its effect on regional myocardial blood flow in patients with coronary artery disease is unknown. In this study, 17 patients with chest pain syndromes who were receiving beta-adrenergic-blocking drugs underwent regional myocardial blood flow determination by the xenon-133 technique before and after the cold pressor test. Nineteen of 28 regions analyzed were distal to significant coronary artery lesions (greater than 70% reduction of luminal diameter), while the remainder were in patients with normal coronary arteries. Patients with normal and stenotic coronary arteries had a similar increase in heart rate-pressure product, but in patients with normal coronary arteries, regional myocardial blood flow increased in nine of nine regions (average increase 11.6 +/- 1.3%, p less than 0.01) while either decreasing or remaining unchanged in 14 of 19 regions distal to coronary artery lesions (average decrease 13.6 +/- 1.6%, p less than 0.05). This difference between groups was significant (p less than 0.01), demonstrating an inappropriate reduction of regional myocardial blood flow and suggesting that alpha-adrenergic vasoconstriction may contribute to myocardial ischemia.

Clinical InvestigationsEquilibrium (Gated) Radionuclide Ejection Fraction Measurement in the Pressure or Volume Overloaded Right Ventricle: Comparison of Three Methods

Although equilibrium radionuclide angiographic measurement of right ventricular ejection fraction (RVEF) has been validated in patients with coronary artery disease, the accuracy of this technique has not been demonstrated in patients with other cardiac diseases which may result in RV pressure and/or volume overload. The accuracy of three methods of equilibrium radionuclide analysis for measuring RVEF was compared in several subgroups of patients with a variety of cardiac diseases, including congenital and valvular heart disease, cor pulmonale, and cardiomyopathy. It was concluded that RVEF may be accurately derived by equilibrium radionuclide ventriculography in patients with a wide variety of cardiac diseases, including those resulting in RV volume and/or pressure overload. Accuracy varies depending on analysis method and the nature of the hemodynamic derangement.