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Biomedical subjects

R S Cosby

Publications and source records attributed to R S Cosby.

At least 19 recordsLinked to original sources
PubMed1978

Regional myocardial blood flow in regions of prior myocardial infarction before and after revascularization.

In 30 patients who received 102 saphenous vein bypass grafts, 91 were patent. Preoperative intracoronary injection of 99mTc-labeled albumin particles suspended in contrast revealed 81 regions of perfusion deficit which subsequently received successful revascularization. With postoperative graft injection of isotope, 48 of these regions no longer showed a perfusion deficit (59%), while 33 showed no change (41%). In these 30 patients, 16 of 17 (94%) revealed perfusion defects in regions of prior transmural myocardial infarction. Conversely, only 55 of 96 regions distal to coronary artery stenosis of greater than 50% revealed perfusion defects (57%). Thus, 99mTc-labeled microsphere studies seem to be valuable in detecting regions of prior infarction. After angiographically documented revascularization, the method continued to reveal perfusion deficits in 41% of abnormal regions noted preoperatively, even though almost half of these same specific regions showed improved postoperative regional contractility after postextrasystolic potentiation.

Cardiac Catheterization↗
PubMed1975

Effect of direct revascularization surgery on coronary collateral circulation in man.

In 63 consecutive patients with significant coronary artery disease (more than 75 percent stenosis), the effects of direct myocardial revascularization on coronary collateral channels were studied 6 to 29 days (mean 13.4 days) after operation. Collateral vessels were identified preoperatively and their angiographic regression or reappearance after operation was noted. In 15 patients (23 percent), there was no evidence of collateral flow before or after operation. The remaining 48 patients had 186 collateral channels preoperatively. Postoperatively, 84 (45 percent) of these collateral vessels were no longer apparent, 75 (40 percent) were unchanged and 27 (15 percent) were identical with the preoperative vessels but the pattern of blood flow was reversed. The findings suggest that in the presence of established collateral channels, direct revascularization acutely alters existing flow and pressure gradients in a complex manner. Collateral channels disappear or remain unchanged when a gradient is decreased or maintained; collateral flow is reversed when a gradient is increased. These data may permit (1) objective preoperative estimation of distal vessel runoff in vessels with collateral channels, and (2) evaluation of the completeness of revascularization in assessing long-term postoperative results.

Collateral Circulation↗
PubMed1975

Left ventricular dyskinesia in infarction and angina.

In 29 patients, the site and extent of coronary artery obstruction were related to the position and area of abnormally contracting segments of the left ventricle, both in patients with a history of angina without myocardial infarction (group I) and in patients with prior documented myocardial infarction (group II). The degree of coronary artery obstructive disease was estimated in the standard manner and also by a coronary artery index which considered not only the degree of obstruction but also the total length of the obstructed segment. A kinetic or dyskinetic segments were present in 22 of the 29 patients. An abnormally contracting segment was present in 12 or 18 patients without prior myocardial infarction in comparison with 10 of the 11 patients with prior infarction. Complete obstruction of a coronary vessel and resultant dyskinesia were more frequent in the right coronary artery than in either the left anterior descending or the circumflex artery. There was a significant correlation between total per cent of vessel obstruction and degree of ventricular asynergy in both groups; consideration of length of obstructed segment did not improve this correlation.

Adult↗