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Biomedical subjects

O C Penn

Publications and source records attributed to O C Penn.

43 records · Page 3Linked to original sources
PubMed1983

Reoperation after aortocoronary bypass procedure. Results in 53 patients in a group of 1041 with consecutive first operations.

Of 1041 patients with consecutive aortocoronary bypass operations, 53 (5.1%) underwent reoperation during a mean follow-up time of three and a half years. The operative mortality of first operations was 1.2%, and of reoperations 3.8%. The anatomical reason for reoperation was failure of the bypass graft in 41 (77%) patients, which in 18 was accompanied by progression of disease. Progression alone was seen in seven (13%). When symptoms occurred within six months after the first operation, failure of the bypass graft(s) was nearly always found--in 32 out of 36 instances. Progression in non-bypassed arteries was seen only when symptoms occurred later. Late results in angina pectoris were less favourable in the group undergoing reoperation: 31 (65%) of the 48 operated on twice and 406 (46%) of the 877 patients operated on once still had angina at late follow-up. The same fraction in both groups was improved by operation: 88% versus 89%.

Adult↗
PubMed1979

Controlled sequential pacing in isolated perfused auxiliary rat hearts.

An important question after clinical auxiliary heart transplantation is whether controlled pacing of both hearts is desirable in order to protect the diseased recipient heart. A comparison of the effects of spontaneous beating with three types of pacing (random, simultaneous and sequential) was undertaken in an isolated perfused working double rat heart. The two hearts were attached to each other by the atria, in a way comparable to the clinical situation. During controlled sequential pacing of both normal hearts, the peak systolic pressure fell and diastolic pressure rose, but the combined cardiac output did not changes. In contrast, during simultaneous pacing, systolic pressure rose, diastolic pressure fell and coronary flow was less than with sequential pacing, but the oxygen uptake was higher. Hence the effects of sequential pacing could be expected to be beneficial when function of one of the hearts was depressed by left main coronary artery ligation. During sequential pacing the cardiac output was significantly improved from 10 to 30 ml/min (P less than 0.001) and coronary flow rose. Myocardial oxygen consumption increased from 80 to 110 microliters/g/min (P less than 0.05). Thus sequential pacing could improve the severely depressed hemodynamics of the coronary-ligated heart in the presence of an auxiliary heart. The increased myocardial oxygen consumption is viewed as a beneficial effect of increased diastolic perfusion pressure and was not associated with increased enzyme release. It is concluded that the effects of sequential pacing warrant assessment in clinical auxiliary heart transplantation.

Animals↗
PubMed1977

Myocardial radiopaque markers used to quantify minor axis shortening for follow-up studies in experimental surgery. I. Recording and analysis techniques. II. Comparison with contractility indices.

This work further validates the use of radiopaque epicardial marker motion for quantifying myocardial shortening in long duration follow-up studies. Mean velocity and extent of minor axis shortening were determined in 8 dogs filmed daily for 6--10 days postoperative. As an independent measure of contractility, peak dP/dt was also determined. A useful approximation to the mean ejection slope was developed which uses the end diastolic minor axis 50 msec after the Q wave, and end systolic minor axis 150 msec after the Q wave of the ECG.

Animals↗
PubMed1976

Histopathology of rejection in DLA-identical canine orthotopic cardiac allografts.

The process of chronic rejection is the limiting factor in long term survival after cardiac transplantation. As part of a study of this process in experimental orthotopic heart transplantation, morphological changes during the course of rejection are described in DLA-identical beagle littermates, obtained by serial percutaneous cardiac biopsy. A total of 153 biopsies were performed on 19 dogs. Mean survival time was 88.11 days (14--494 days) without the use of immunosuppressive therapy. Eight dogs, surviving only 4 weeks, showed a histological pattern that resembled delayed acute rejection, with extensive lymphocellular infiltrate, vascular damage, and myocytolysis. In the 11 dogs which survived more than 4 weeks there was a slight and sometimes transient lymphocellular infiltrate. But progressive vascular lesions could be seen from the 2nd week consisting mainly of medical proliferation involving intramural vessels as well as epicardial vessels. Capillary changes were prominant and the rate of capillary damage seems to be an indication of graft survival prognosis.

Animals↗
PubMed1976

Orthotopic canine heart transplantation: left ventricular contractility during chronic rejection.

Myocardial left ventricular contractility is assessed in 8 orthotopic heart-transplanted dogs during chronic rejection by a noninvasive method. The mean circumferential velocity of shortening (Vcf) is calculated from endocardial marker motion on cinefilms. A model for chronic rejection after cardiac transplantation was obtained by histocompatibility matching in DLA identical Beagle littermates. No immunosuppressive treatment was used. All dogs eventually died of chronic rejection; mean survival time was 112.5 days. LV contractility shows the following pattern: Chronic rejection causes an important contractility decrease (P less than 0.001) with two significant drops: (1) from the week preoperative to the first week after transplantation (P less than 0.02) and (2) from week terminal minus one to the terminal week (P less than 0.01). This study describes the technique and the changes in Vcf observed over a period of time in a predictable model.

Animals↗
PubMedDate not supplied

Color Doppler imaging of the right gastroepiploic artery as an in situ coronary artery bypass graft.

In recent years the right gastroepiploic artery (GEA) has been used as an in situ graft in coronary artery bypass grafting (CABG). The specific anatomical course of the GEA graft enables the use of color Doppler imaging technique to evaluate its patency. The results in 21 patients demonstrate the efficiency of this technique; postoperative angiography to establish patency can therefore be avoided.

Aged↗