Coronary Washout Research Articles

Endothelial glycocalyx during early reperfusion in patients undergoing cardiac surgery

BackgroundExperimental cardiac ischemia-reperfusion injury causes degradation of the glycocalyx and coronary washout of its components syndecan-1 and heparan sulfate. Systemic elevation of syndecan-1 and heparan sulfate is well described in cardiac surgery. Still, the events during immediate reperfusion after aortic declamping are unknown both in the systemic and in the coronary circulation.MethodsIn thirty patients undergoing aortic valve replacement, arterial concentrations of syndecan-1 and heparan sulfate were measured immediately before and at one, five and ten minutes after aortic declamping (reperfusion). Parallel blood samples were drawn from the coronary sinus to calculate trans-coronary gradients (coronary sinus–artery).ResultsCompared with immediately before aortic declamping, arterial syndecan-1 increased by 18% [253.8 (151.6–372.0) ng/ml vs. 299.1 (172.0–713.7) ng/ml, p < 0.001] but arterial heparan sulfate decreased by 14% [148.1 (135.7–161.7) ng/ml vs. 128.0 (119.0–138.2) ng/ml, p < 0.001] at one minute after aortic declamping. There was no coronary washout of syndecan-1 or heparan sulfate during reperfusion. On the contrary, trans-coronary sequestration of syndecan-1 occurred at five [-12.96 ng/ml (-36.38–5.15), p = 0.007] and at ten minutes [-12.37 ng/ml (-31.80–6.62), p = 0.049] after reperfusion.ConclusionsAortic declamping resulted in extracardiac syndecan-1 release and extracardiac heparan sulfate sequestration. Syndecan-1 was sequestered in the coronary circulation during early reperfusion. Glycocalyx has been shown to degrade during cardiac surgery. Besides degradation, glycocalyx has propensity for regeneration. The present results of syndecan-1 and heparan sulfate sequestration may reflect endogenous restoration of the damaged glycocalyx in open heart surgery.

Newborn hearts are at greater ‘metabolic risk’ during global ischemia – advantages of continuous coronary washout

Altered metabolic responses of the newborn heart to ischemia, which may increase irreversible injury, may at least partially explain the greater morbidity and mortality experienced by some children undergoing congenital cardiac repair. The present study compared newborn heart metabolic responses to global ischemia with those of adult, and evaluated whether continuous coronary artery washout in the newborn heart during 'ischemia' could favourably affect these responses. Adult (n=12) and newborn (n=12) pigs were anesthetized, and right ventricular biopsies were taken before global ischemia and at set intervals during ischemia. Another 12 newborns were subdivided into groups of nonperfused hearts and hearts receiving continuous perfusion. Time to onset of and time to peak of ischemic contracture were recorded. Biopsies were assayed for lactate, myocardial glycogen, glucose-6-phosphate and ATP. Newborn hearts were more sensitive to global ischemia than adult hearts, based on shorter time to onset of and time to peak of ischemic contracture, and had a significantly greater rate of ATP decline (P<0.01). This was due in part to a more rapid accumulation of lactate (P<0.05) and only a 50% use of glycogen, compared with 93% by adult hearts. Continuous washout of newborn hearts prevented lactate accumulation, allowing a 90% use of glycogen and delaying time to ischemic contracture by twofold. This was accompanied by lower levels of glucose-6-phosphate accumulation (P<0.05) and a threefold reduction in the rate of ATP decline. Significant differences in myocardial metabolism during ischemia in newborns compared with adults could predispose them to earlier ischemic injury, which can be eliminated by the removal of end products. Perfusion strategies taking these differences into account may further optimize pediatric myocardial protection and improve outcomes in newborn children undergoing cardiac procedures.

Comparison of washed blood and oxygenator whole blood as vehicles for sanguinous multidose cardioplegia

The effects of washed blood or oxygenator-traumatized whole blood as vehicles for sanguinous cardioplegia were studied utilizing the isolated blood-perfused dog heart preparation. Hearts were subjected to 2 hr of potassium-induced arrest at 27°C followed by 90 min of normothermic reperfusion. Washed blood cardioplegia ( n = 7) contained blood washed thrice with saline while oxygenator blood cardioplegia ( n = 6) contained whole blood which had been exposed to an extracorporeal circuit for 30 to 45 min. Cardioplegic solutions were administered at a perfusion pressure of 100 mm Hg every 15 min during arrest. While the arrest-reperfusion sequence caused minor variations in the mechanical, metabolic, and biochemical parameters tested, generally insignificant differences were found to exist between groups. Differences in coronary washout PCO 2 appeared to be due to inherent differences between the two cardioplegic solutions. Thus, while washing blood may be thought to be beneficial and whole blood from the extracorporeal circuit may be theorized to have a deleterious effect on the myocardium, excellent recovery of mechanical function was observed with both cardioplegic solutions. The present study suggests that it is unnecessary to wash the sanguinous cardioplegic solution obtained from the cardiopulmonary circuit.

Myocardial protection by coronary washout during global ischemic cardiac arrest

The effect of intermittent coronary washout (WO) during global ischemic cardiac arrest (ICA) was evaluated in isolated blood perfused dog hearts undergoing 90 min normothermic ICA and 90 min reperfusion. WO consisted of infusion of 100 ml normothermic dog plasma at 100 mm Hg every 10 min during ICA. Systolic and diastolic pressures were measured at constant volume with a left ventricular balloon. Coronary blood flow (CBF) was measured, and transmyocardial oxygen, lactate, and glucose differences were calculated. Adenosine triphosphate (ATP), creatine phosphate (CP), calcium (Ca 2+), glycogen, and water content were measured from left ventricular biopsies. During 90 min of WO, hearts extracted glucose (15 ± 4 mg/g dry wt LV) and lost lactate (90 ± 5 μmole/g dry wt LV). ATP and CP were significantly depressed at arrest in both groups although WO resulted in significantly higher levels of ATP and CP. CP returned to control levels at 90 min reperfusion in the WO group but remained depressed in the ICA group. Calcium accumulation was greater in hearts with ICA. With reperfusion, both ICA and WO groups demonstrated early hyperemia and rapid lactate washout. There were no differences in total CBF, AVO 2, MOV 2, and myocardial glycogen or water content. Systolic performance was equally depressed in both groups at 90 min of reperfusion. Diastolic compliance, while still impaired, was better preserved in WO when measured in the arrested heart at 90 min ICA ( P < 0.01) and in the contracting heart after 90 min reperfusion ( P < 0.02). Normothermic coronary washout during 90 min of normothermic ischemic arrest without cardioplegic agents produces improved ventricular compliance and energy metabolism, and reduces myocardial calcium accumulation.

Effects of coronary washout on cardiac function during brief periods of ischemia and hypoxia.

Coronary washout has been shown effective in preserving metabolism during hypoxia, but its impact on mechanical function is unknown. To investigate this, experiments were conducted in a regionally perfused swine heart preparation (n = 19) in which oxygen (O2) delivery was repetitively restricted for short times (3 min) by randomly changing coronary flow (delta Qc) and/or arterial oxygen content (delta O2a) in the perfusion circuit. Recovery periods in each animal were at least 15 min between trials. Changes in metabolism and mechanics were expressed as a function of delta Qc and delta O2a (the two independent determinants) using linear regression equations. Significance and the ranking of importance for the two determinants were estimated by F testing, the t values of the respective regression coefficients, and partial regression analysis. Myocardial oxygen consumption (MVO2) was dependent on both flow and O2 content (MVO2% = 115.8 + 0.8 delta Qc% + 1.1 delta O2a%). However, regional mechanical function, including total shortening (TS) and an index of work (Indexw), was dependent only on arterial O2 content, e.g., TS% = 94.9 + 0.1 delta Qc% + 0.8 delta O2a% and Indexw% = 85.5 + 0.2 delta Qc% + 1.1 delta O2a%. In these latter relationships, O2 content ranked higher than Qc by factors of 7.39:1 and 5.34:1, respectively. Thus it was concluded that coronary washout offers no selective advantages in preserving average regional mechanical function during short-term O2 deprivation.

Effects of coronary washout on mechanical function in hypoxic swine hearts: A.J. Liedtke & S.H. Nellis. Penn State University, Hershey, Pa.

Effects of coronary washout on mechanical function in hypoxic swine hearts: A.J. Liedtke & S.H. Nellis. Penn State University, Hershey, Pa.

Reduction of Intraoperative Myocardial Infarction by Means of Exogenous Anaerobic Substrate Enhancement: Prospective Randomized Study

In a prospective study, patients who had an ejection fraction of 40% or more and who were undergoing elective coronary artery operation were randomly divided into three groups that differed in the method of anaerobic substrate enhancement during cardiopulmonary bypass. Group 1, the controls (n = 157), received no additional glucose, insulin, and potassium solutions and experienced immediate spontaneous defibrillation (10%), transmural myocardial infarction (10.3%), malignant ventricular arrhythmias (26%), and severe atrial arrhythmias (20%). Group 2 (n = 120) received a bolus of hypertonic glucose, insulin, and potassium in the pump perfusate before aortic cross-clamping. In this group, the rate of spontaneous defibrillation was 41%, of transmural infarction, 8.3%, of malignant ventricular arrhythmias, 31%, and of severe atrial arrhythmias, 19%. Group 3 (n = 114) had the aortic root continuously infused with glucose, insulin, and potassium solution at 4° during aortic cross-clamping. This group was significantly improved; the rate of spontaneous defibrillation was 60%, there were no transmural myocardial infarctions and the incidence of severe atrial arrhythmias was 6% and that of malignant ventricular arrhythmias, 5%. It is proposed that the superior clinical results in Group 3 resulted from better myocardial preservation achieved by more efficient means of providing continuous anaerobic substrate, coronary washout, and elution of lactic acidosis, uniform global hypothermia, and direct supplemental myocardial potassium in addition to mere cardioplegic effects.

Cardiac Valve Replacement in Patients Over 65 During a 10-year Period

From 1967 through 1976, 754 adult patients were subjected to open heart procedures for acquired valvular disease at the University of California, San Francisco, 104 of whom were 66 years of age or over (mean = 70 years). The operative mortality of 15.0% in the elderly group did not differ significantly from that of 14.3% in the entire adult series for the 10-year period. Mortality was consistently higher in combined procedures (multiple valve replacement and valve replacement with coronary grafting). Since the introduction, in 1973, of hypothermic hyperkalemic coronary washout for intraoperative protection of the ischemic myocardium, the hospital mortality rate has decreased to 8.1% overall, 6.0% for isolated aortic valve replacement and 0% for isolated mitral valve replacement in patients over 65. Moreover, the long-term survival following aortic and mitral valve replacement in this series appears to approximate the survival curve of the normal population of the same age. This experience suggests that cardiac surgery has become safer for all patients during the past 10 years and that operative mortality is related primarily to the type and severity of disease rather than to age.

A nomogram relating pO2, pH, temperature, and hemoglobin saturation in the dog.

Abstract : The data from 591 dog blood samples on which observations were made of Po sub 2, hemoglobin saturation, Pco sub 2, pH, and temperature were analyzed by means of a digital computer. The Hill equation was found to fit the data well in the range from 20% to 98% saturation. Linear terms for pH and temperature effects were found to improve appreciably the prediction ability of the equation. A similar term for Pco sub 2, although statistically significant, did not contribute enough additional precision in prediction to justify its inclusion in the final equations. The equations derived are: log (S/1-S) = 2.5198 log Po sub 2 + 1.1804 (pH-7.0) - .047234T - 2.3621 and log Po sub 2 = .37143 log (S/1-S) - .48047 (pH-7.0) + .019518T + .92247. A nomogram relating these variables is also presented. (Author)