The effects of myocardial ischemia followed by reperfusion on perfused coronary capillarity.

To determine the effects of ischemia and reperfusion on myocardial perfused capillary density, rat hearts were excised, kept ischemic for thirty minutes then reperfused with blood from a support animal. Control hearts were isolated and perfused for either 10 or 60 minutes before injection of a vascular marker (Monastral Blue-blood mixture, 30 sec at 100 mmHg). The ischemic hearts were perfused with Blue after 10 minutes of reperfusion. The perfused capillary density (theta) and capillary/fiber ratio (C/F) were measured from frozen transverse sections of the left ventricle. For 10- and 60-minute control hearts, the epicardial theta values were 2324 +/- 476 caps/mm2 and 2378 +/- 330 SD. The endo/epi theta ratio was not significantly less than unity for either control group. For the ischemic group, theta was significantly decreased both in the epicardium (707 +/- 515 caps/mm2) and endocardium (130 +/- 30 caps/mm2) (p less than 0.05). The endo/epi theta ratio was significantly less than unity for the ischemic group (P less than 0.05). The C/F ratio analysis yielded the same results. The decrease in both theta and CF ratio indicate that 30 minutes of ischemia followed by 10 minutes of reperfusion caused a marked "No-reflow" phenomena in isolated, supported hearts. The No-reflow was most pronounced in the endocardium.

Role of procaine and washed red cells in the isolated dog heart perfused at 5 degrees C.

Isolated dog hearts were perfused for 24 hours at 5 degrees C with one of three solutions: plain Krebs solution, Krebs solution containing 167 mg/L of procaine hydrochloride, or Krebs-procaine solution with washed red cells (hematocrit 2%). Coronary vascular resistance (CVR) of hearts perfused with Krebs solution alone increased sharply between the eighth and the twelfth hours of perfusion and then stabilized. Increase of myocardial firmness paralleled the increase of CVR. The addition of procaine to Krebs perfusate kept the heart flaccid and suppressed the steplike increase in CVR but failed to improve significantly the preservation of the hearts. The addition of washed red cells to Krebs perfusate kept CVR near baseline level, improved coronary perfusion flow, doubled myocardial oxygen consumption, reduced edema formation, and improved left ventricular stroke work (LVSW) of the preserved heart. This improvement seems mostly related to a mechanical effect of red blood cells on capillary flow distribution of the heart.

Protection by plasma proteins of the isolated lamb heart perfused with stroma-free hemoglobin at 38 degrees.

Isolated lamb hearts were perfused for eight hours at 38 degrees with stroma-free hemoglobin solution (SFHS). The preservation of cardiac structure and function was studied. Control hearts perfused with blood (N = 6) developed no ventricular failure or significant weight gain (13% +/- 5), showed no alteration of cellular ultrastructure, and little interstitial edema. Hearts perfused with 7% (N = 7) or 11% (N = 5) SFHS contracted less well, became edematous (22% and 44% weight gain) and showed altered mitochondria, capillary endothelial swelling and hemoglobin extravasation into the interstitial space. The addition of 5-7% albumin to SFHS (N = 9) markedly reduced interstitial edema (weight gain 11% +/- 13), preserved mitochondria, prevented endothelial swelling, and limited transcapillary escape of hemoglobin. Thus isolated hearts perfused with SFHS develop vascular endothelial damage and an increase in capillary permeability. The addition of plasma proteins to the perfusate protects against this injury.

The Ito "Flow-Through" Centrifuge. A new device for long-term (24 hours) plasmapheresis without platelet deterioration.

An efficacious procedure for continuous plasmapheresis in long-term extracorporeal circulation has not yet been devleoped. This technique could be important in plasma exchange or cross-exchange and in artificial organ support if it could be accomplished safely using heparin as the anticoagulant. When sheep were connected to the Celltrifuge for 23 hours and administered 150 units/kg per hour heparin anticoagulant, we found gross platelet clumping in separated plasma and a 60 per cent fall in platelet count. When 120,000 units of heparin were directly injected into the centrifuge bowl at the onset of the centrifugation followed by hourly heparin administration at 500 units/kg, there was no platelet clumping but the platelet count fell to 52 per cent. Under identical conditions the Ito Flow-Through Centrifuge, a new continuous flow centrifuge with no rotating seals, was used. We found no platelet aggregates and no drop in platelet count, and there was a 100 per cent recovery of platelets in the separated plasma. Platelets sampled from arterial blood and separated plasma were found to have normal function in vitro, and responded 100 per cent to both collagen and ADP. These results indicate that the Ito Flow-Through Centrifuge can be used in plasmapheresis with heparin anticoagulation with no donor platelet loss and normal function in separated plasma.

Fresh platelet-rich plasma from a flow-through centrifuge for lamb heart perfusion at 13degrees C. Protective effect of added erythrocytes.

Isolated lamb hearts perfused at 13degrees C. with acellular perfusates developed progressive intersitital edema and a rise in vascular resistance. They did not exhbit any electrical or mechanical activity. In contrast, hearts perfused with whole fresh blood remained well preserved, had no edema or change in vascular resistance, and contracted vigorously while being perfused at 10degrees and 13degrees C. This study was designed to determine which particular component(s) of whole blood contributed to improved cardiac preservation. Isolated lamb hearts were perfused for 18 hours at 13degrees C. with plasma containing platelets and some or no red blood cells. Continuously fresh plasma was obtained from a donor animal by means of a flow-through centrifuge. Hearts perfused at 13degrees C. with fresh plasma of either low or high platelet count contracted during the initial 2 to 4 hours of the perfusion only and were as poorly preserved as hearts perfused with acellular microfiltered plasma. A hematocrit value of 2 to 5 per cent in the plasma perfusate resulted in the hearts being preserved almost as well as with fresh whole blood; they showed a forceful cardiac activity at 13degrees C., there was no edema, the vascular resistance was stable, and after rewarming they had good ventricular function. The improvement in cardiac preservation brought about by addition of a minimal amount of red blood cells suggests a specific effect of erythrocytes on the cardiac microcirculation.

New flow-through centrifuge without rotating seals applied to plasmapheresis.

The flow-through centrifuge eliminates complications arising from rotating seals. Preliminary studies on plasmapheresis demonstrated negligible platelet injury and no evidence of hemolysis during 12 hours of operation. Thus the system may provide a broad application to cell washing and elutriation, zonal centrifugation, and countercurrent chromatography.