Masataka Hayashi

F-18 deoxyglucose and stress N-13 ammonia positron emission tomography in anterior wall healed myocardial infarction

To evaluate myocardial blood flow and glucose utilization, N-13 ammonia (NH3) and F-18 deoxyglucose positron emission tomography scanning was performed in 22 patients with previous anterior wall myocardial infarction, using a high-resolution, multi-slice, whole-body scanner. The N-13 ammonia study was performed at rest and after exercise. The F-18 deoxyglucose study was performed at rest after fasting greater than 5 hours. The N-13 ammonia study revealed a hypoperfused area in 19 of the 22 patients (86%), that corresponded to the infarcted regions as diagnosed by electrocardiography, coronary arteriography and left ventriculography (21 patients). The hypoperfused areas expanded after exercise in 16 of 22 patients (73%). F-18 deoxyglucose uptake was observed in these hypoperfused areas, especially in patients with hypokinetic wall motion on left ventriculography and in exercise-induced hypoperfused areas. However, positron emission tomography demonstrated diffuse uptake of F-18 deoxyglucose in 3 of 8 patients with dyskinetic wall motion. Thus, metabolically active myocardium in infarcted areas or periinfarct ischemia can be visualized with F-18 deoxyglucose and stress N-13 ammonia studies.

Non-Q wave versus Q wave myocardial infarction: regional myocardial metabolism and blood flow assessed by positron emission tomography

This study compared regional myocardial blood flow at rest and during supine exercise as well as regional myocardial glucose utilization in the fasting condition in 22 patients, 11 with antecedent non-Q wave and 11 with antecedent Q wave infarction. With use of N-13 (nitrogen-13) ammonia and F-18 (fluorine-18) deoxyglucose as tracers of blood flow and exogenous glucose utilization and positron emission tomography, hypoperfused areas were noted at rest and during exercise in all 11 patients (100%) with Q wave infarction. Among the 11 patients with non-Q wave infarction such areas were noted in only 5 (45%) at rest and in 8 (73%) during exercise. Furthermore, segmentally enhanced F-18 deoxyglucose uptake corresponding to the infarcted areas (identified electrocardiographically) was seen in 10 (91%) of the 11 patients with non-Q wave infarction but in only 4 (36%) of the 11 patients with Q wave infarction (p less than 0.01). In conclusion, segmental F-18 deoxyglucose uptake as a possible sign of myocardial viability was seen more frequently in non-Q wave than in Q wave infarction and, importantly, regionally enhanced F-18 deoxyglucose uptake occurred even in the absence of segmental rest or exercise blood flow abnormalities, or both, in 5 (45%) of 11 patients with non-Q wave infarction.

Increased fluorine-18 deoxyglucose uptake after percutaneous transluminal coronary angioplasty in recently infarcted myocardium.

Abstract Positron emission tomography (PET) allows the noninvasive assessment of relative myocardial perfusion and glucose utilization in humans. 1 Relative myocardial perfusion is assessed with nitrogen-13 ammonia and relative glucose utilization is assessed with the glucose analog fluorine-18 deoxyglucose. Using this technique, we will describe 2 patients whose infarcted areas revealed new fluorine-18 deoxyglucose uptake many weeks after successful percutaneous transluminal coronary angioplasty (PTCA).

Effects of Nifedipine on Cardiac Function in Patients with Coronary Artery Disease Evaluated with Ambulatory Radionuclide Monitoring

SummaryThe effects of nifedipine on left ventricular function were evaluated in 17 patients with coronary artery disease with an ambulatory radionuclide detector (VEST). Hemodynamic data were recorded continuously at rest and during upringht bicycle ergometer exercise before and 30 minutes after 10 mg of oral nifedipine administration. The heart rate increased and the resting systolic blood pressure decreased significantly with nifedipine. The end-diastolic and end-systolic volumes during exercise were significantly reduced and EF increased during exercise after nifedipine administration. These salutary hemodynamic responses of nifedipine appear to be beneficial for patients with effort angina pectoris.

Direct Measurement of Aortic and Vena Caval Flow to Evaluate the Effect of Vasodilators in Experimental Acute mitral regurgitation

To evaluate the effect of bunazosin hydrochloride (Bz), a newly developed α1-blocker, on arterial and venous blood flow and on left ventricular function in acute left heart failure, we produced acute mitral regurgitation in seven open chest anesthetized dogs by transmyocardial chordal sectioning. With the administration of Bz (1μg/kg/min for 5 minutes intravenously) or nitroprusside (Np: 1.7 μg/kg/min for 3 to 5 minutes intravenously), the mean aortic pressure and systemic vascular resistance (SVR) decreased to the same levels. With Np, cardiac output (CO) did not change (from 1.80±0.72 to 1.87±0.80 L/min; NS), and mean inferior vena caval blood flow (IVCF) decreased by 5.5% (from 1.25±0.40 to 1.19±0.40 L/min; p < 0.01.). With Bz, CO increased significantly from 1.83±0.46 to 1.98±0.72 L/min (p < 0.05), and IVCF also increased significantly from 1.09 + 0.34 L/min to 1.18 + 0.33 L/min (p < 0.01). This suggests that Bz decreases SVR to the same level as Np, but the vasodilatory effect of Bz on the venous system is smaller than that of Np. We conclude that Bz is useful in treating heart failure where cardiac output must be augmented, while maintaining venous return.