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W Bircks

Publications and source records attributed to W Bircks.

197 records · Page 11Linked to original sources
PubMedDate not supplied

Ischemic tolerance of the human heart during extracorporeal circulation: clinical experience.

Our clinical experiences with ischemic tolerance of the human heart under the condition of ECC during the last 15 years allow us to state the following points: 1. The healthy human myocardium can be exposed to ischemia without danger on the basis of 15 min and a myocardial temperature of 35 degrees C. This time can be prolonged following the described value of Q10=2. 2. The previous damaged human myocardium is usually not able to cover this range. Frequently ischemic load within these limits causes functional deterioration. So, in such cases ischemic tolerance has to be applied on a distinct lower base. 3. Occasional transgressions of the described ischemic tolerance time without a fatal result do not allow us in our clinic to leave the effective principles in daily routine.

Coronary Disease↗
PubMedDate not supplied

Reliability of intraoperative flow measurements to determine early graft patency with simultaneous introduction of a new method for distal coronary artery run-off capacity.

Intraoperative measurements of blood flow were made in 44 patients in whom a total of 112 venous bypass grafts were inserted. Blood flow through the graft was measured by a standard electromagnetic device as well as by a new method, consisting of a roller pump run-off system. At an average of 5 months after operation all patients underwent control coronaro-angiography. Overall patency-rate was 86.6%. Using the standard method mean flow in the patent grafts was 78 ml/min and 39 ml/min in the occluded grafts. Using the new run-off method mean flow in the patent grafts was 142 ml/min and 78 ml/min in the occluded grafts. It is concluded that measuring distal coronary artery run-off capacity provides a reliable index for predicting patency rate. For several reasons roller-pump run-off measurement has advantages over the generally used electromagnetic measurements.

Adult↗
PubMedDate not supplied

Energy demand of cardioplegically perfused human hearts.

Human adult hearts with aortic valve disease (n = 20) and hypertrophic obstructive cardiomyopathy (n = 1) were perfused intraoperatively with cold histidine buffered Bretschneider solution. During a seven minute cardioplegic perfusion the temperature level, the electrolyte level, the resistance of the left (LCA) and right coronary artery (RCA), and myocardial O2 consumption were analysed. Equilibration of K+ was terminated shortly after the start of the perfusion while Na+ equilibration lasted for about 5 minutes. Resistance of RCA did not change significantly, but that of the LCA was diminished significantly (p less than 0.025) within the perfusion period indicating a delayed washout of calcium from the extracellular space. Myocardial O2 consumption was reduced from 2.71 ml/min (1. minute) to 1.51 ml/min (4. minute) to 0.93 ml/min (7. minute) although the temperature had reached a low level after 3 minutes. The difference between 4. to 7. minutes is significant (p less than 0.001). By our results it is concluded that in adult hearts high-volume cardioplegic perfusion at a flow rate of 1 ml/min X gm at a perfusion pressure of 40 to 50 mmHg should be performed for at least 6 to 7 minutes to achieve a sufficient intra-ischemic myocardial protection.

Adult↗
PubMedDate not supplied

Scanning-electron-microscopic and functional studies of oxygenator-membranes during long-term-perfusion.

Various types and amount of deposits were noted on the surface of different membrane oxygenators during experimental long-term perfusion in sheep studied by SEM. They were present in spite of adequate heparinization. The deposition of blood material suggests, that the imperfection of the membranes by fabrication must be controlled and improved by oneself for use in long-term perfusion.

Animals↗