Influence of attenuation on radionuclide stroke volume determinations.

Using a method for determination of absolute volumes, including correcting for attenuation, we have explored the ability of the method to determine stroke volume in humans by radionuclide techniques. Thermodilution cardiac output determinations and multigated equilibrium blood-pool scintigraphy in the LAO view were performed simultaneously in twenty patients in which no evidence of intracardiac shunts or valvular disease was present. The correlation was good between the attenuated radionuclide and thermodilution stroke volume (r = 0.80, s.e.e. of estimate = 12 ml; SVtd = 2.31 x SVr + 18 ml). When correction for attenuation was made, the correlation improved (r = 0.96, s.e.e. = 6 ml) and approached the line of identity (SVtd = 0.99 x SVr + 1.2 ml). The correlation was also good between radionuclide cardiac output, corrected for attenuation, and the thermodilution cardiac output (r = 0.89, s.e.e. = 0.36 l/min; COtd = 0.86 x COr + 0.67 l/min). Thus our method of correction for attenuation in the determination of absolute left-ventricular volumes has been shown to provide a reliable, noninvasive means of calculating stroke volume and cardiac output in humans, without the use of geometric assumptions or regression equations.

Aspirin for the prevention of vascular death in women.

OBJECTIVE: To review current information relevant to the use of aspirin for preventing vascular death in women, and to provide recommendations based on this information. DATA SOURCES: References from pertinent articles are identified throughout the text. DATA SYNTHESIS: Based on current information, low-dose aspirin is not recommended as primary prevention for cardiovascular death in women; efforts are better focused at promoting risk-factor reduction. Low-dose aspirin is recommended for reducing further cardiovascular morbidity and mortality in women with known cardiovascular disease. Women presenting with unstable angina or myocardial infarction should receive aspirin 325 mg as soon as the diagnosis is confirmed, and this dosage should be continued on a chronic basis. Women who have experienced transient ischemic attacks or ischemic stroke should receive aspirin 1000 mg/d, with a subsequent dosage reduction to 325 mg/d in patients who do not tolerate the higher dose. CONCLUSIONS: Current recommendations are based on the results of studies that involved few women. Further investigation of antiplatelet agents for primary and secondary prevention of vascular death in women is needed.