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Biomedical subjects

D R Kahn

Publications and source records attributed to D R Kahn.

At least 55 records · Page 3Linked to original sources
PubMed1976

The Blalock-Taussig operation: the procedure of choice in the hypoxic infant with tetralogy of Fallot.

From 1971 to 1975, 17 consecutive patients aged 1 day to 4 years underwent Blalock-Taussig shunts for severe tetralogy of Fallot. Three infants were under 6 weeks of age and 7 (41%) under 1 year. There were no hospital deaths. Modification of the shunt technique adapts it to any size infant. The subclavian artery is divided at its major branches and the end spatulated to enlarge it. The artery is occluded while the shunt is constructed. No intraoperative complications were encountered; all patients have a shunt murmur with no early or late closure. No child has had heart failure or hypoxic spells. Flows measured at operation equaled one-quarter to one-half of the child's normal cardiac output. Ligation of the shunt at subsequent repair is uncomplicated. One child died three years later at correction from causes unrelated to the shunt. With appropriate modifications in technique, the Blalock-Taussig shunt is the operation of choice, at any age, for palliation of severe tetralogy of Fallot.

Cardiac Output↗
PubMed1976

Quinidine syncope. A report of successful treatment with bretylium tosylate.

Quinidine syncope is an unpredictable side effect of quinidine administrateion which has a mortality rate of 11.5 per cent when managed with conventional drugs and direct-current countershock. In 2 patients with quindine syncope, the arrhythmias were effectively controlled within 30 minutes following the slow infusion of 150 mg. of bretylium tosylate. This control is contrasted with 2 cases managed in the conventional manner. Bretylium tosylate is a quaternary amine with unique antifibrillatory properties and appears to have a significant role in the management of these arrhylmias.

Adult↗
PubMed1975

Effects of partial obstruction on phasic flow in aortocoronary grafts.

Phasic blood flow recorded in five unobstructed dog aortocoronary bypass grafts to the left coronary artery was similar to that of normal coronary arteries, with a high diastolic-to-systolic flow ratio which averaged 2.7 +/- 0.4. With an average of 52 +/- 7% and 72 +/- 6% stenosis in the coronary artery distal to the graft, the phasic graft-flow pattern was altered, with a decrease in the diastolic-to-systolic flow ratio to 1.9 +/- 0.4 and 1.2 +/- 0.4, respectively. Phasic patterns recorded in 42 human saphenous vein grafts to branches of the left coronary artery subsequently shown to be patent by postoperative coronary arteriography were similar to those of a normal coronary artery, with an average diastolic-to-systolic flow ratio of 2.3 +/- 0.83 and an average flow of 76 +/- 48 ml/min. Phasic flow measured in 20 grafts shown to be occulded at restudy had an average diastolic-to-systolic flow of 1.3 +/- 0.45, with an average flow of 72 +/- 33 ml/min and a phasic graft flow which was similar to that obtained from partially obstructed coronary arteries. We conclude that partial obstruction of the graft or the distal coronary artery alters the flow pattern, and this partial obstruction may lead to closure of the graft.

Animals↗
PubMed1975

Prolonged perfusion with a membrane oxygenator in awake ponies.

Prolonged extracorporeal membrane oxygenation (PEMO) was performed in 6 adult ponies with the membrane oxygenator in vein-to-artery bypass circuit. A flow rate equal to 46 per cent of control cardiac output was diverted through the PEMO circuit of 10 to 24 hours. Three of the 6 ponies were perfused for at least 20 hours and developed no complications. Immediately following initiation of PEMO, left ventricular output decreased; however, in the interval between 6 and 24 hours, left ventricular output was increased above control levels. Aortic pressure and left ventricular work were markedly elevated during PEMO. Pulmonary ventilation and oxygen uptake also decreased initially but were elevated during later stages of bypass. Pulmonary compliance did not change, except in those studies in which problems were encountered with perfusion techniques. Hepatic glycolysis and hyperglycemia occurred and were more severe in ponies with catheter-produced thrombi. Marked diuresis, which could be attributed only partially to the hyperglycemia, was present throughout PEMO. Based on the minimal morphologic changes observed in the ponies, extracorporeal circulation diverting one half of the cardiac output through a membrane oxygenator can be safely performed for up to 24 hours.

Animals↗
PubMed1975

Predictive value of mixed leukocyte culture testing on allograft survival in unrelated dogs.

This study evaluated the mixed leukocyte culture (MLC) technique to quantitate differences in kidney allograft survival between unrelated animals. Each of five beagles received two heterotopic kidney allografts, one from a mongrel dog showing high MLC stimulation and one from a second mongrel dog showing a low MLC stimulation. Low or high stimulators were defined by the amount of radioactive thymidine incorporated by lymphocytes when the recipient was tested against a number of potential donors in one way MLC TESTS. Low and high stimulators usually differed by a factor of up to ten in the stimulation index. Recipients were given a standard treatment of asathioprine and prednisone. No special treatment was given for rejection episodes. Creatine clearances and periodic biopsies were used to determine rejection. Creatine clearances and biopsies showed the high stimulating kidneys to be rejected completely by the end of 2 weeks in all animals. All of the low stimulating kidneys maintained normal function for 3 weeks and then developed progressive deterioration and rejection over the next 3 to 6 weeks. These studies suggest that quantitation of the MLC may be predictive of kidney allograft survival in unrelated dogs.

Animals↗
PubMed1975

Energy reserves in transplanted and sham-operated carciac tissue=.

Tissue levels of creatine phosphate (CP), creatine, adenosine-triphosphate(ATP), inorganic phosphate (Pi), glycogen, glucose and lactate were determined in heterotopically transplanted and recipient hearts as well as in the myocardium of sham-operated rabbitsmthe ATPase activity in these tissues was also estimatedmthe results revealed no biochemical indication of ischemic conditions in the transplanted organs relative to the other investigated tissue. The tissue levels of CP in the donor heart were even higher then in both the recipient and sham-operated organs. The concentrations of the other above listed compounds in all the studied tissue were similar throughout the first 5 post-operative days. The effect of surgery was manifested in decreased levels of CP, still prevailing 3 days post-operative in all of the investigated tissue. However, on the fifth day after surgery, the tissue concentration of CP showed a trend toward recovery. The activity of Na,K-ATPase in both donor and recipient hearts was similar. One day after surgery, the activity of the Mg-ATPase was 27% lower relative to its value on days 3 and 5 post-operatively. However no correlation was obtained between the change in Mg-ATPase and tissue concentrations of ATP.

Adenosine Triphosphatases↗
PubMed1975

Histochemical and structural changes in human myocardial cells after cardiopulmonary bypass.

The histochemical and ultrastructural effects of extracorporeal circulation and aortic cross-clamping during coronary heart surgery have been examined in drill biopsy samples of the left ventricle in 22 patients. The biopsies were obtained before and after bypass with a DeSoutter drill. Histochemical studies indicated definite differences between control and experimental biopsies, with increased succinic dehydrogenase, cytochrome oxidase, and LDH activity, while phosphorylase A and myosin ATPase activities declined. Furthermore, free phospholipid levels increased, as determined by the acid hematein reaction. Ultrastructural examination demonstrated loss of glycogen, intracellular swelling, and mitochondrial damage, which included loss of matrix density, loss of cristae, and eventual disruption in the postbypass biopsy. These results, which closely resemble the effects of ischemia and reperfusion observed in animal experiments, suggest that the initial insult is a change in membrane permeability regulation.

Adenosine Triphosphatases↗