Biomedical subjects
Publications and source records attributed to D R Kahn.
A 63 year old woman with a large true posterior ventricular aneurysm and mitral regurgitation is presented. Simple aneurysmectomy without replacement or repair of the mitral valve completely alleviated the mitral insufficiency.
We tested the ability of various cardiac preservation techniques to preserve left ventricular function of isolated canine hearts using preservation temperatures of 4 degrees or 15 degrees C. The four techniques tested were: (1) topical hypothermia, and hypothermic arrest induced by (2) perfusion of 1 liter of a modified Collins solution, (3) perfusion of 1 liter of a modified extracellular solution (DKS), or (4) perfusion of 500 ml of blood cardioplegia. Following the cold ischemia period, the hearts were reperfused with blood in the working heart preparation and tested for their ability to recover left ventricular function. Hearts preserved 2 hours at 15 degrees C using hypothermia, modified Collins solution, or DKS solution achieved an average of 60, 73, and 95%, respectively, of baseline function. Hearts preserved 3 hours at 4 degrees C using topical hypothermia attained 70% of baseline function, while hearts stored 5 hours at 4 degrees C using modified Collins solution or DKS solution recovered 83 and 92%, respectively, of baseline function. Hearts preserved at 4 degrees C functioned at levels equal to or greater than that of hearts stored at 15 degrees C, even though the hearts preserved at 4 degrees C were stored for longer periods than those preserved at 15 degrees C. Hearts preserved with blood cardioplegia for 2 hours at either 4 degrees or 15 degrees C achieved functions statistically the same as baseline levels during the reperfusion period. These data show no advantage for preservation temperatures of 15 degrees C compared with 4 degrees C. Our data provide a firm experimental basis for the clinical use of myocardial preservation temperatures of 4 degrees C, especially when combined with cardioplegia.
Heart and kideny allografts showed markedly prolonged survival in unrelated mongrel dogs following total lymphoid irradiation (TLI) and donor bone marrow without any other immunosuppression. In every animal the heart survived longer than the kidney; genetic disparity was ruled out, since the heart and kidney from the same donor were placed into one recipient. Placing the kidney allograft in the abdomen with the bone marrow given intraperitoneally doubled kidney survival over placement in the neck, but heart survival was equally prolonged in the abdomen or neck. Splenectomy before TLI or after TLI, but just before transplantation, almost completely eliminated the prolonged survival of both heart and kidney allografts. Thus there is suggestive evidence from the work of Slavin and his colleagues and from our study that TLI plus bone marrow from the donor may be valuable for transplantation in man, particularly heart transplantation.
Hearts preserved for 2 hours at 15 degrees C were evaluated for maximum function with the use of an isolated working dog heart subjected to stress. We determined left ventricular function by controlling aortic flow resistance and flow into the left atrium. Groups studied were hypothermia alone (H), hypothermia with a modified extracellular solution (H + DKS), hypothermia with a modified Collins solution (H + C), six periods of 20 minutes of hypoxic hypothermia followed by 10 minutes of blood reperfusion (H20 + R10) and blood cardiplegia (BC). Hypothermia alone for 1 hour was also evaluated. Functions were studied for 2 1/2 hours following reperfusion by determining Starling's curves for each heart. Our data show that H alone gave adequate myocardial protection for only 1 hour but not for 2 hours. H20 + R10 was better than H, but function was depressed. Use of H + C provided protection equal to H20 + R10, but the hearts recovered function slowly. Only hearts preserved by H + DKS and BC for 2 hours had normal function. Hearts from all groups except H + DKS and BC became edematous. Excellent function was obtained with DKS or BC following 2 hours of ischemia at 15 degrees C. Initial clinical use of BC supported these laboratory findings.
We have shown previously that acute aortic insufficiency in chronically instrumented dogs reverses the normally high ratio of diastolic to systolic coronary blood flow. Phasic blood flow in the dominant right coronary artery was measured directly with an electromagnetic flow meter during surgery in eight patients with severe aortic insufficiency before and after relacement of the aortic valve. Before the insufficiency was eliminated, right coronary flow average 116 +/- 37 ml./minute and the diastolic to systolic flow ratio was 0.88 +/- 17. Mean arterial blood pressure averaged 106 +/- 17 mm. Hg, heart rate 84 +/- 19 beats/minute, and mean diastolic pressure averaged 67 +/- 10 mm. Hg. After the aortic valve was replaced with an average heart rate of 90 +/- 15 and mean blood pressure of 103 +/- 13 mm. Hg, the average right coronary blood flow increased to 180 +/- 40 ml./minute with a D/S ratio of 2.18 +/- 0.8. In all cases the right coronary blood flow increased after the aortic insufficiency was eliminated surgically. Right coronary flow probably increased because of the improved diastolic perfusion pressure and the change from predominantly systolic to diastolic coronary flow.
99mTechnetium macroaggregated albumin has successfully been used to define severe postoperative pulmonary vasoconstriction in a four-month-old boy with D-transposition of the great vessels who had undergone a Blalock-Hanlon surgical atrial septectomy. Radionuclide imaging documented clinically suspected pulmonary vasoconstriction and led to the successful use of tolazoline (Priscoline) to reverse the vasoconstriction with improved pulmonary blood flow patterns.
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Sixteen patients have undergone Carpentier ring annuloplasty for severe mitral insufficiency (MI) since 1974. Our criteria were clinical and angiographic evidence of severe noncalcific MI, a dilated mitral anulus, absence of severe subvalvular chordal thickening, and no major loss of leaflet substance. Carpentier annuloplasty has been successful in eliminating MI in every patient except one. There have been no embolic problems and no early or late deaths. From 1971 to 1974, a similar group of 20 patients with the same diagnosis underwent prosthetic valve replacement. Even though all patients were receiving anticoagulant drugs, three had emboli and there were one early and three late deaths. In patients with severe noncalcific MI who meet our criteria, Carpentier ring annuloplasty is preferable to valve replacement, thus eliminating the hazards of a prosthesis and of long-term anticoagulant therapy.
A patient with total occlusion of the distal right pulmonary artery secondary to the performance of a Waterston shunt is reported. A nearly fatal intrapulmonary steal occurred at the time of corrective operation when an attempt was made to revascularize both pulmonary arteries.
A technique is presented to eliminate the residual gradient more completely after removing the main pulmonary band at the time of primary repair of ventricular septal defect. The band and underlying pulmonary artery are circumferentially excised, except for a small posterior part, and pulmonary artery is reanastomosed.
A routine chest X-ray taken four months after blunt chest trauma revealed a left ventricular aneurysm in a totally asymptomatic patient. At surgery a thin-walled, clot-filled aneurysm was successfully removed. This case demonstrates the need for careful follow-up of all patients sustaining blunt chest trauma even though the initial cardiac evaluation may be negative. Our feeling that all such aneurysms should be treated surgically is further reinforced by our operative findings.
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Tweleve patients with the complete form of persistent atrioventricular (AV) canal were operated upon at the University of Wisconsin between May, 1972, and November, 1975. The technique originally described by Rastelli and his associates was used. All 12 patients are asymptomatic and well, with no hospital or late deaths. Postoperative cardiac catheterization in 8 patients showed a return to near normal dynamics, with minimal residual mitral insufficiency. Half of these children had type A and half type C malformations; both types could be repaired without the need for valve replacement. Since 3 of these patients were less than 2 years of age, we now feel that complete repair of the AV canal can be undertaken in children between 12 and 18 months of age for optimal management.