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M A Jacocks

Publications and source records attributed to M A Jacocks.

23 records · Page 2Linked to original sources
PubMed1982

Comparison of myocardial preservation with hypothermic potassium and nifedipine arrest.

Preservation of regional myocardial function, high-energy phosphate stores and ultrastructure were assessed in 28 canine hearts subjected to 2 hours of global ischemia at either 12 degrees C or 21 degrees C. The preservation achieved with a potassium arrest solution was simultaneously compared in the same heart with either a nifedipine arrest solution or a potassium plus nifedipine arrest solution. There were no statistically significant differences in regional function recovery between the three arrest solutions at either temperature. At 12 degrees C, slightly better functional preservation was noted for each solution. End-systolic chord length was significantly less elongated after preservation at the lower temperature (p = 0.03). The concentration of ATP and myocardial water content were not significantly better preserved with any solution at either temperature. Myocardial ultrastructure was well preserved regardless of the solution or temperature used. The degree of hypothermia appears to be more important to functional preservation than differences between the three solutions tested. We conclude that with respect to preservation of myocardial function, high-energy phosphate stores, water content and ultrastructure, nifedipine arrest offers no advantages over potassium arrest.

Adenosine Triphosphate↗
PubMed1981

Regional myocardial protection during aortic cross-lamp ischemia in dogs: calcium-containing crystalloid solutions.

To study the effects of calcium in cardioplegic solutions, an in situ dog heart model was used that allowed infusion of two different cardioplegic solutions into separate regions of the same heart. Two concentrations of ionized calcium, 1.0 mM and 0.5 mM, in a cold, potassium-containing solution were tested in two groups of dogs and compared with the same cold, potassium-containing solution but without the calcium, during 100 minutes of global myocardial ischemia induced by aortic clamping. Results were evaluated in terms of percent change of regional systolic shortening measured with ultrasonic piezoelectric crystals, percent change of regional myocardial blood flow, and change of regional left ventricular myocardial diastolic distensibility. No significant differences were found between myocardial regions protected with calcium of either concentration and regions protected with calcium of either concentration and regions protected without calcium. This study could demonstrate no beneficial or adverse effects of including calcium in this type of crystalloid cardioplegic solution applied to an in situ dog heart model.

Animals↗
PubMed1981

Myocardial temperature mapping. Improved intraoperative myocardial preservation.

An improved approach to intraoperative myocardial preservation technique to ensure uniform myocardial cooling past critically stenosed arteries was developed for patients undergoing aorta-coronary bypass grafting. Proximal anastomoses are done and then, after institution of cardiopulmonary bypass, a separate roller pump head is used to administer a specific controlled volume of cardioplegic solution (1 L) through a 4 degrees C coil to provide controlled pressure in the root of the cross-clamped aorta. Midmyocardial wall temperatures in the anterior, posterolateral, inferior, and septal walls of the left ventricle are measured. Distal anastomoses are then performed sequentially, beginning with the warmest region. After each distal anastomosis, 400 ml of cardioplegic solution are again administered into the aortic root. This approach has been used in 100 consecutive patients from July, 1979, through July 1980 (Group I). and these patients were compared to 97 consecutive patients undergoing aorta-coronary bypass grafting in the previous year (July, 1978, through June, 1979) (Group II) who had myocardial preservation with potassium cardioplegia administered by syringe injection and without regional temperature mapping. There were no perioperative myocardial infarctions in Group I: there were five (5.2%) in Group II (p less than 0.05). A significant reduction in cardiac deaths was also achieved, with two (2.0%) such deaths in Group I and eight (8.2%) in Group II (p less than 0.05). The data suggest that delivery of adequate volumes of cardioplegia solutions by a pressure-regulated system, in combination with myocardial temperature mapping to determine the sequence of bypass grafting, can improve myocardial preservation.

Body Temperature↗