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Biomedical subjects

D G Pennington

Publications and source records attributed to D G Pennington.

At least 163 records · Page 9Linked to original sources
PubMed1978

Ventricular performance and myocardial water content during hemodilution in dogs.

In dogs anesthetized with chloralose-urethan on right heart bypass, left ventricular (LV) performance was assessed at constant LV stroke work before and for up to 2.5 h after crystalloid hemodilution was established. Lowering the hematocrit from 43.3 +/- 1.3% to 13.6 +/- 1.7% (SE) did not significantly change LV end-diastolic pressure (LVEDP) initially. After 80 min LVEDP increased slightly by 1.7 +/- 0.6 cmH2O (P less than 0.05) at a stroke work of 17.3 +/- 2.3 g.m. The value of dP/dt did not change significantly throughout. When LV function curves were generated by increasing cardiac output, the stroke work attained at an LVEDP of 10 cmH2O decreased with hemodilution from 23.9 +/- 3.5 to 20.8 +/- 3.9 g.m (NS). LV wall water content increased with hemodilution, from which it could be calculated that there was an 18.6% increase in LV mass. Thus, despite an increase in LV external girth demonstrated by LV circumferential gauges, it is possible that increased wall thickness due to the water gain resulted in little change or an actual decrease in LV end-diastolic volume. Thus, profound hemodilution can be attained with only slight depression of LV performance.

Anemia↗
PubMed1976

Coronary vascular responses to nitroglycerin following aorta-coronary saphenous vein grafting in dogs.

Phasic coronary arterial flow responses to nitroglycerin were evaluated in 15 open-chest greyhounds before and after aorta-coronary saphenous vein grafting. Coronary flow was measured with electromagnetic probes proximal and distal to the vein graft site. Simultaneous measurements of branchiocephalic flow, aortic and left atrial pressure, left ventricular pressure, and dp/dt were made. Grafts were placed during normothermic hemodilution cardiopulmonary bypass and induced ventricular fibrillation. Before grafting, intravenous nitroglycerin (0.6 mg.) elicited an abrupt rise in diastolic coronary flow which decreased as aortic pressure fell and systolic coronary flow increased. However, after grafting, nitroglycerin elicited no change in diastolic coronary flow, whereas systolic coronary flow increased and aortic pressure fell. In 6 control dogs treated similarly except for aorta-coronary grafting, coronary flow responses to nitroglycerin were unchanged. These acute experiments suggest that, in dogs with aorta-coronary saphenous vein grafts, the coronary dilating effect of nitroglycerin is virutally abolished.

Animals↗
PubMed1975

Cerebral metastasis from melanoma.

Fifty-seven patients suffering from melanotic cerebral metastases are reviewed. The nature and course of the primary lesion, the clinical history of the cerebral metastases and the results of treatment are discussed. Radiotherapy, chemotherapy, surgery and immunotherapy formed the basis of treatment.

Brain Neoplasms↗
PubMedDate not supplied

Long-term follow-up of survivors of postcardiotomy circulatory support.

Although it is now possible to obtain, with mechanical circulatory support devices, survival of postcardiotomy patients who develop profound cardiogenic shock, their long-term functional status has not been firmly established. We studied 22 patients who survived cardiac operations by the use of circulatory support devices. Their ages ranged from 3 days to 69 years at the time of device support. Operations performed were coronary artery bypass (9 pts), valve replacement (4 pts), congenital defect correction (8 pts), and cardiac transplantation (1 pt). Ten patients were supported with a Pierce-Donachy ventricular assist device (VAD) (left 4, right 3, both 3), nine with extracorporeal membrane oxygenation (ECMO), and three with centrifugal pumps (left 2, both 1). Duration of support ranged from 22 to 189 hours (mean 84.4). There were four late deaths; two of the deaths were cardiac-related within 6 months and two were due to cancer at 46 and 53 months following discharge. The remaining 18 survivors were followed for 6 to 74 months (mean 29.9). Prior to operation three of the patients were New York Heart Association (NYHA) Class I, eight were Class II, six patients were Class III, and five were Class IV. Following discharge from the hospital 13 patients were Class I, two were Class II, and three were Class III; no patients were Class IV. Five patients work full-time, three are retired without limitation, four attend school, and three are pre-school. Only three patients suffer from moderate cardiac disability. These data suggest that patients surviving mechanical circulatory assistance for postoperative cardiogenic shock have an excellent chance for functional recovery.

Assisted Circulation↗
PubMedDate not supplied

Predictors for weaning patients from ventricular assist devices.

In order to determine if hemodynamic parameters can accurately predict whether patients can be successfully weaned from ventricular assists devices (VADs), we studied 24 patients supported with Pierce-Donachy VADs (11 left VAD; 6 right VAD; 7 biventricular VAD) following cardiogenic shock for periods from 1.3 to 22 days (mean 5.4). Myocardial recovery was determined by daily measurements of "pump on/pump off" parameters, and the data from seven LVAD patients (64%) and three RVAD patients (50%) whose hearts recovered were compared to the data from those whose did not. Additionally, data from the five patients (71%) weaned from biventricular support were compared to those weaned from only a single LVAD or RVAD. In this study, daily pump on/pump off hemodynamic measurements were found to be predictive of success for weaning patients from VADs. The most significant predictors were increases in mixed venous oxygen saturation, cardiac index, mean arterial pressure and ventricular ejection fraction, as well as decreases in atrial pressures. Seventy percent of the patients weaned from VADs survived, indicating that patients appropriately weaned from VAD support have a reasonable chance of survival.

Assisted Circulation↗