PubMed Health⌕ Search

Biomedical subjects

W Santamore

Publications and source records attributed to W Santamore.

5 recordsLinked to original sources
PubMed1984

Potentiation of coronary vascular platelet adhesion by atrial pacing in the presence of arterial stenosis in dogs.

The effect of atrial pacing on coronary hemodynamics and platelet adhesion was evaluated in 13 dogs. In all 13 dogs, a snare was placed around the circumflex artery and tightened so that distal coronary artery pressure decreased to 60 to 70 mm Hg. In 10 dogs, atrial pacing was instituted at twice the heart rate at rest for 10 minutes. In three dogs, observation was continued for 10 minutes without pacing. In the 10 dogs undergoing pacing, heart rate increased from 90.5 +/- 32.6 to 173.5 +/- 45.8 beats/min. Aortic pressure was unchanged. Distal coronary artery pressure decreased from 70.8 +/- 7.8 to 53.2 +/- 10.0 mm Hg (p less than 0.05) and the pressure gradient across the stenosis increased from 47.6 +/- 12.7 to 61.2 +/- 9.1 mm Hg (p less than 0.05). Stenotic resistance increased from 2.5 +/- 0.8 to 3.6 +/- 2.4 mm Hg/ml X min-1, but coronary flow was unchanged. In all three control dogs, there was no change in coronary dynamics for the 10 minute period. In 8 of the 10 dogs that underwent pacing, platelet deposition was observed at the site of coronary stenosis. In contrast, in the three control dogs there was no platelet deposition. Atrial pacing in the presence of coronary stenosis appears to alter coronary hemodynamics such that there are activation and deposition of platelets at the site of stenosis. This platelet deposition may be transient or could become the nidus for subsequent platelet-related events in the coronary vessel.

Animals↗
PubMed1982

Monitoring regional myocardial function after myocardial revascularization.

A system using only small platinum electrodes for monitoring intramyocardial polarographic oxygen tension (MP02), electrograms (ECG), and impedance-derived wall motion (WM) was experimentally tested and clinically implemented. In nine open-chest, anesthetized dogs. two platinum electrodes were inserted along the subepicardial direction of the muscle fibers. As verified by cinefluoroscopy, WM corresponded to changes in distance between the platinum electrodes (r = 0.91 +/- 0.02). The system responded to a 10 minute occlusion of the left anterior descending coronary artery (LAD) as follows: Dyskinetic WM appeared in 10 seconds (p less than 0.05); MP02 decreased (26.4 +/- 1.8 to 14.8 +/= 1.9 mm Hg, p less than 0.05) in 1 minute; ST segments increased (4.8 +/- 1.5 to 12.3 +/- 3.1 mV, p less than 0.05) in 3 minutes. On reperfusion, WM, ST segments, and MP02 normalized in 15 seconds, 30 seconds, and 1 minute, respectively. Hence, ischemia affects WM more acutely than either ECG or MP02. In five patients, ischemic changes before coronary bypass were reversed over 5 days: MP02 (17.4 +/-; 1.9 to 19.6 +/-1.7 mm Hg), ST segment (2.2 +/- 6 to 1.0 +/- 0.4 mV), and WM returned to normal. Thus a system has been designed which simultaneously monitors regional WM, MP02, and ECG. The method has proved to be a sensitive and practical approach for assessing perioperative myocardial function.

Animals↗