L. R. Poliner

Left ventricular performance in normal subjects: a comparison of the responses to exercise in the upright and supine positions.

Left ventricular (LV) performance at rest and during multilevel exercise in the supine and upright positions was studied in seven normal subjects with equilibrium radionuclide ventriculography. The mean left ventricular end-diastolic volume (LVEDV) during supine rest was 107 4 10 ml (± SEM) and 85 ± 6 ml (p < 0.02) in the upright position; the mean resting left ventricular end-systolic volumes (LVESV) were not diSferent in the upright and supine positions. The LV ejection fraction (LVEF) tended to be slightly higher in the supine (76 ± 2%) than in the upright position (72 4%). The resting hpart rate was 89 + 5 beats/min upright, compared with 71 ± 6 beats/min supine (p < 0.05). Multilevel exercise testing was carried out at a low work load of 300 kpm/min, an intermediate work load of 600–750 kpm/min and a peak work load of 1092 66 kpm/min supine and 946 ± 146 kpm/min upright (p < 0.05). With peak exercise, supine LVEDV increased significantly, to 135 ± 13 ml (27%), but LVESV did not change. LVEF increased from 76 ± 2% to 84 i 2% (p < 0.05). With upright exercise, LVEDV increased 39% above the resting level, to 116 ± 8 ml (p < 0.02), but remained lower than the supine LVEDVs at intermediate (p < 0.05) and peak work loads. LVESV decreased significantly by 41%, to 19 ± 3 ml, and was significantly smaller than the corresponding supine volume at intermediate and peak exercise (p < 0.05). LVEF increased from 72 ± 4% to 91 ± 2% (p <0.05), which was significantly higher than peak supine LVEF (p < 0.05). Heart rates at rest and during exercise were higher in the upright position (p < 0.05), but arterial pressures and double products did not differ significantly.Measurements of LV volumes at rest and during exercise in both the supine and upright positions by dynamic radionuclide scintigraphy suggest that stroke volume during exercise is maintained by a combination of the Frank-Starling mechanism and an enhanced contractile state.

Clinicopathologic findings in 52 patients studied by technetium-99m stannous pyrophosphate myocardial scintigraphy.

Scintigraphic, clinical and pathological findings were correlated in 52 patients studied by technetium-99m stannous pyrophosphate (99mTc-PYP) myocardial scintigraphy before death or surgical resection of myocardium. Fifty-nine clinical events were studied with scintigraphy in the 52 patients; 41 of the 59 were associated with one or more abnormal 99mTc-PYP studies and 18 with normal 99mTc-PYP scintigrams. Myocardial scintigrams were positive in 29 of 31 cases with clinicopathological evidence of a corresponding discrete, grossly obvious acute myocardial infarct, including 16 of 16 transmural myocardial infarcts and 13 of 15 subendocardial infarcts. In 16 of 18 cases, negative myocardial scintigrams correlated with the absence of acute myocardial infarction determined by clinicopathological evidence. In two cases small subendocardial infarcts (less than 3 g) were not detected by 99mTc-PYP myocardial scintigraphy. Of the 12 additional instances of positive 99mTc-PYP myocardial scintigrams, five were associated with clinical unstable angina pectoris and seven were in the category of persistently positive scintigrams, since the scans were obtained 2.5 months or longer after proven or suspected acute myocardial infarcts. In all 12 instances, the positive 99mTc-PYP scintigrams were associated with evidence of multifocal irreversible myocardial damage consisting of myocytolysis, coagulation necrosis and/or fibrosis, and the histological age of the lesions was compatible with acute injury corresponding to the time of scintigraphy. The findings indicate that a positive 99mTc-PYP myocardial scintigram is a sensitive indicator of significant myocardial injury which may occur as confluent coagulation necrosis corresponding to clinical acute myocardial infarction, or as multifocal coagulation necrosis or myocytolysis associated with unstable angina pectoris or recurrent ischemic heart disease, especially after previous infarctions.

Unstable angina pectoris: a randomized study of patients treated medically and surgically.

Fifty patients with the clinical syndrome of unstable angina pectoris were evaluated. Twenty-seven were randomized into medical or surgical treatment groups and subsequently followed up. The results of the study reveal that: (1) there is approximately a 16 percent incidence rate of significant left main coronary artery disease in patients with this entity at our institution; (2) 10 percent of patients do not have angiographically significant coronary artery disease; (3) pain relief is better in the surgically treated patients, but the 1 1/2 year survival rate is not significantly different between the groups; (4) 50 percent of the medically treated patients again had the syndrome of unstable angina pectoris in the initial few months of the follow-up period; (5) the operative and late postoperative mortality rate in patients presenting with unstable angina pectoris and left main coronary artery disease in this small group of patients was 43 percent; and (6) four of six patients with this syndrome whose condition was deemed inoperable and who were not randomized died within the subsequent few months.

Cardioversion and "false positive" technetium-99m stannous pyrophosphate myocardial scintigrams.

SUMMARY The present studies performed in experimental animals demonstrate that electrical direct current cardioversion can produce skeletal muscle damage and increased technetium-99m stannous pyrophosphate (99mTc-PYP) uptake; in experimental animals the electrically damaged skeletal muscle shows necrosis with extensive calcium deposition. In addition, the frequent administration of high energy cardioversion produces myocardial necrosis with calcium deposition, increased 99mTc-PYP myocardial uptake and a positive 99mTc-PYP myocardial scintigram. The data indicate that, if diag- nostic 99mTc-PYP myocardial scintigraphy is contemplated after cardioversion, paddle placement should be slightly removed from the anteroposterior projection of the heart on the external chest wall to avoid possible subsequent confusion between increased myocardial and skeletal muscle uptake of 99mTc-PYP. If multiple high energy cardioversion episodes are necessary, myocardial necrosis resulting from electrical injury may occur and be responsible for increased myocardial uptake of 99mTc-PYP with a resultant positive 99mTc-PYP myocardial scintigram.