Cardioplegia at subnormothermia facilitates rapid functional resuscitation of hearts preserved in SOMAH for transplants.

OBJECTIVES: Hearts preserved ex vivo at 4 ° C undergo time-dependent irreversible injury due to extreme hypothermia. Studies using novel organ preservative solution SOMAH, suggest that hearts are optimally 'preserved' at subnormothermic temperature of 21 ° C. Present study evaluates relative efficacy of SOMAH 'cardioplegia' at 4 and 21 ° C in preservation of optimum heart function after in vitro storage at subnormothermia. METHODS: Porcine hearts arrested with SOMAH cardioplegia at 4 or 21 ° C were stored in SOMAH for 5-hour at 21 ° C (n = 5). At the end of storage, the weight of hearts was recorded and biopsies taken for cardiac tissue high energy phosphate level measurements. The hearts were then attached to a reperfusion apparatus and biochemical parameters including cardiac enzyme release and myocardial oxygen consumption and lactate production were determined in perfusate samples at regular intervals during ex vivo perfusion experiment. Functional evaluation of the hearts intraoperatively and ex vivo was performed by 2D echocardiography using trans-esophageal echocardiography probe. RESULTS: Post-storage heart weights were unaltered in both groups, while available high-energy phosphates (HEP) were greater in the 21 ° C group. Upon ex vivo reperfusion, coronary flow was significantly greater (p < 0.05) in 21 ° C group. 2D echo revealed a greater cardiac output, fractional area change and ejection fraction in 21 ° C group that was not significantly different than the 4 ° C group. However, unlike 4 ° C hearts, 21 ° C hearts did not require inotropic intervention. Upon reperfusion, rate of cardiac enzyme release temporally resolved in 21 ° C group, but not in the 4 ° C group. 21 ° C working hearts maintained their energy state during the experimental duration but not the 4 ° C group; albeit, both groups demonstrated robust metabolism and function during this period. CONCLUSIONS: Rapid metabolic switch, increased synthesis of HEP, decreased injury and optimal function provides evidence that hearts arrested at 21 ° C remain viably and functionally superior to those arrested at 4 ° C when stored in SOMAH at ambient temperature pre-transplant. ULTRAMINI-ABSTRACT: Cardioplegic arrest and preservation of hearts in SOMAH at ambient temperature efficiently conserves metabolism and function in in vitro porcine model of heart transplant.

Sub-normothermic preservation of donor hearts for transplantation using a novel solution, Somah: a comparative pre-clinical study.

BACKGROUND: Hearts preserved ex vivo at extreme hypothermia (4°C) undergo time-dependent irreversible injury. Our studies using a novel solution, Somah, suggest that hearts are viably preserved at 21°C. In this study we evaluate the relative efficacy of Somah for preservation of hearts at 21°C when compared with the clinically used Celsior and University of Wisconsin (UWS) solutions. METHODS: Porcine hearts arrested by cardioplegia at 21°C using Somah, Celsior or UWS solution were stored in the respective solutions at 21°C (n = 5) for 5 hours and then reperfused ex vivo for functional assessment. We assessed development of edema, cardiac tissue high-energy phosphate (HEP; ATP + creatine phosphate) levels and release of cardiac enzymes. Alterations in left ventricular wall thicknesses and functional parameters were examined by 2-dimensional (2D) echocardiography. Changes in myocardial oxygen consumption (MVO2) and lactate utilization were assessed at reperfusion. RESULTS: Heart weights were unaltered during 5-hour storage in all groups. After storage, HEP levels were 28.33 ± 5.51, 10.20 ± 2.78 and 5.92 ± 1.46 nmol/liter per milligram protein (p < 0.001) in the Somah, Celsior and UWS group hearts, respectively. Upon reanimation, 2D echocardiography showed edema in the Celsior and UWS hearts; prompt attainment of physiologic function was associated with rapid establishment of aerobic metabolism not requiring stimulatory interventions in the Somah hearts, but not in the Celsior/UWS hearts. Percent fractional area change, ejection fraction and stroke volume were significantly higher (p < 0.001) in Somah hearts than in Celsior and UWS group hearts. CONCLUSIONS: Increased synthesis of HEP, rapid metabolic switch and optimal function together provide evidence that hearts procured for transplantation are preserved in a superior viable condition at 21°C with Somah, but not with other commonly used clinical preservation solutions.

Multifactorial comparison of modified and conventional perfusion strategies in a porcine model of cardiopulmonary bypass.

BACKGROUND: Utilization of thromboresistant circuits in cardiopulmonary bypass (CPB) surgery has been controversial. However, due to the advantages associated with these types of circuits, we sought to evaluate the efficacy of use of low-dose heparin in conjunction with thromboresistant surfaces, closed perfusion system, elimination of blood-gas interface, maintenance of hematocrit to >25%, and systemic normothermia, with respect to the conventional strategy of non-thromboresistant open circuits with high-dose heparin, during 3 h of CPB in an animal model. METHODS: Using an open-chest swine model, animals were placed on CPB for 3 h with additional monitoring for 1 h post-CPB. Pigs were randomized into either a heparin-bonded circuit (HBC) group (n = 10) or a non-HBC (NHB) group (n = 10). Hemodynamic, hematologic, and biochemical parameters and multiphoton microscopy were used to compare the two groups. RESULTS: Pigs in the HBC group showed a 38.4% reduction in post-CPB blood loss in comparison with the NHB group (P = 0.0007). Additionally, compared with the HBC group, the NHB group exhibited a 32.7% post-CPB reduction in platelets (P < 0.001) and significant increases in alkaline phosphatase, aspartate aminotransferase, and creatine phosphokinase enzymes (P < 0.0202, P = 0.0015, P < 0.0001; respectively). Multiphoton imaging of the arterial filters revealed no entrapment of RBC, WBC, and platelets in the HBC group, while the filters in the NHB group were clogged by these cells. CONCLUSION: Utilization of modified perfusion strategy employing low-dose heparin and closed thromboresistant circuits is successful in ameliorating the potential adverse hematologic and pro-inflammatory elements induced with open perfusion system of non-thromboresistant circuits most commonly used in cardiac surgery.

Thromboresistant surfaces with low-dose anticoagulation alleviate clopidogrel-related complications in patients undergoing coronary artery bypass grafting.

OBJECTIVE: Numerous studies have shown that, when using conventional perfusion methodology, patients undergoing coronary artery bypass grafting within 7 days of receiving clopidogrel are at increased risk of bleeding, re-exploration, and blood transfusion. The purpose of this study was to evaluate the effect of clopidogrel administration before coronary artery bypass grafting on patients using thromboresistant surfaces with low-dose heparin during surgical intervention. METHODS: Patients who underwent isolated coronary artery bypass grafting between 2005 and 2009 were incorporated in this retrospective study. Of these, 52 (22.2%) received clopidogrel within 5 days before the operation, and 182 (77.8%) did not. Regression models determined the effect of clopidogrel on the rate of chest re-exploration because of bleeding, 24-hour chest tube output, perioperative blood product transfusion, length of stay, morbidity, and perioperative mortality. Hemorrhage-related preoperative risk factors, as well as those found to be significant in univariate models, were included in the multivariate model. RESULTS: Chest tube drainage was significantly increased during the first 24 hours after the operation in the clopidogrel group (679.7 ± 305.8 vs 516.6 ± 209.8 mL, P = .0007). The need for intraoperative blood product transfusion was similar; nevertheless, more patients receiving clopidogrel required fresh frozen plasma postoperatively (7.7% vs 1.1%, P = .0232). However, risk-adjusted logistic regression showed that exposure to clopidogrel was not a predictor of intraoperative or postoperative blood product transfusion. Lengths of stay in the intensive care unit and hospital were shorter in patients receiving clopidogrel. CONCLUSIONS: Hemostatic complications related to clopidogrel exposure within 5 days before an isolated coronary artery bypass grafting operation can be alleviated by the application of a biocompatible perfusion strategy using low-dose heparin in conjunction with a closed thromboresistant circuit.

Evaluation of blood components exposed to coated arterial filters in extracorporeal circuits.

BACKGROUND: Biocompatible surfaces play an important role in the inflammatory response during cardiopulmonary bypass (CBP), with the arterial filter contributing a large surface area of the circuit. Different filter-coating materials designed to improve blood-filter biocompatibility are currently used in CPB circuits. This study evaluates eight biocompatible coatings used for arterial filters and their effects on blood components during circulation. METHODS: Arterial filters were randomly assigned in eight independent heparin-bonded tubing loops and perfused by a single swine (n=8). Arterial blood was routed simultaneously, but separately, into each circuit and circulated for 30 minutes at 37 degrees C. Blood samples were drawn for CBC, ACT, and TAT III measurements at baseline, post-heparinization and post-circulation. At study completion, filters were imaged using multiphoton microscopy. RESULTS: RBC, platelet, and WBC counts, and TAT III complex were all decreased after 30 minutes of circulation; however, WBC count was the only parameter that showed statistically significant differences between the filters. Circulating WBC reduction ranged from 6% (Carmeda and Trillium) to 41% (Terumo-X-coating) with corresponding microscopic confirmation of increased WBC entrapment. CONCLUSION: All eight filter coatings altered the blood components to varying degrees. Selection of the most effective filter, in conjunction with a heparin-bonded circuit for CPB, may decrease the intraoperative foreign-surface activation of blood cells.

Development and evaluation of a novel solution, Somah, for the procurement and preservation of beating and nonbeating donor hearts for transplantation.

BACKGROUND: Injury to myocytes, endocardium, and the coronary endothelium during harvesting and storage can compromise outcomes after heart transplantation. Safeguarding of structure and function of cardiomyocytes and endothelium in donor hearts may lead to improved patient survival after transplantation. Information gained from porcine hearts stored in standard transplant solution was used to design a superior preservation solution that would optimally protect and maintain organs from beating heart and/or nonbeating heart donors during long-term storage. METHODS AND RESULTS: Multiphoton microscopy was used to image deep within cardiac biopsies and coronary artery tissue harvested from porcine hearts obtained from beating heart and nonbeating heart donors for analysis of myocyte and endothelial cell structure and function. Cell structural integrity and viability, calcium mobilization, and nitric oxide generation were determined with fluorescence viability markers, immunofluorescence, and Western blots. During hypothermic storage in standard preservation solution, Celsior, myocyte, and endothelial viability was markedly attenuated in hearts obtained from beating heart donors. In contrast, hearts from beating and nonbeating heart donors stored in the newly formulated Somah solution demonstrated an increase in high-energy phosphate levels, protection of cardiac myocyte viability, mitochondrial membrane polarization, and structural proteins. Similarly, coronary artery endothelial organization and function, calcium mobilization, and nitric oxide generation were well maintained during temporal storage in Somah. CONCLUSIONS: The Celsior preservation solution in clinical use today has led to a profound decline in cardiomyocyte and endothelial cell viability, whereas the newly designed Somah solution has safeguarded myocyte and endothelial integrity and function during organ storage. Use of Somah as a storage medium may lead to optimized graft function and long-term patient survival after transplantation.

Intraoperative myocardial acidosis as a risk for hospital readmission after cardiac surgery.

BACKGROUND: This study elucidates the relationship between intraoperative myocardial acidosis/ischemia and the risk of unplanned hospital readmissions within 30 days and 6 months after cardiac surgery. METHODS: Myocardial tissue pH (corrected to 37 degrees C: pH(37C)) was monitored in 221 patients during cardiac surgery. Regional myocardial acidosis was defined in terms of specific pH thresholds. RESULTS: Fourteen percent and 27% of the patients were readmitted within 30 days and 6 months postoperatively, respectively. The mean number of readmissions was 1.67 +/- 1.24; pH(37C) <6.85 at the end of cardiopulmonary bypass (CPB) was identified as the threshold most significantly associated with readmission. This threshold was associated with a 6-fold increased risk of readmission within 30 days and a 5-fold increased risk within 6 months. CONCLUSIONS: Persistent regional myocardial acidosis after weaning from CPB independently determines unplanned readmission rates up to 6 months postoperatively. This study underscores the importance of avoiding myocardial tissue acidosis during cardiac surgery.

Patients with diabetes mellitus undergoing cardiac surgery are at greater risk for developing intraoperative myocardial acidosis.

OBJECTIVE: In patients undergoing cardiac surgery, intraoperative myocardial acidosis, which quantifies regional myocardial ischemia, has been shown to increase the risk of adverse postoperative outcomes. In this study, we sought to determine the course of intraoperative myocardial acidosis and its impact on postoperative survival in patients with diabetes mellitus undergoing cardiac surgery. METHODS: Intraoperative myocardial tissue pH(37C) was continuously measured in the anterior and posterior left ventricular walls in 264 patients undergoing cardiac surgery; 74 (28.0%) of the patients had diabetes (insulin-dependent diabetes: 54%; non-insulin dependent diabetes: 46%). The shortest time required to reach intraoperative myocardial tissue pH < 6.34 during aortic occlusion and > 6.73 during reperfusion were compared in 3 patient groups: insulin-dependent, non-insulin dependent, and nondiabetic. These pH thresholds have been demonstrated to be associated with adverse postoperative long-term survival. RESULTS: The median times to reach intraoperative myocardial tissue pH(37C) < 6.34 during aortic occlusion were 14, 23, and 36 minutes in the insulin-dependent, non-insulin dependent, and non-diabetic groups, respectively (P = .003). The time taken to reach intraoperative myocardial tissue pH(37C) > 6.73 during reperfusion was similar between the 3 groups. After adjusting for relevant pre- and intraoperative parameters, the risk of developing intraoperative myocardial tissue pH < 6.34 during aortic occlusion was 73% higher in patients with insulin-dependent diabetes mellitus (P = .022) but the same in with patients with non-insulin dependent diabetes mellitus (P = .98) when compared with patients without diabetes. Patients with insulin-dependent diabetes mellitus also had nearly threefold decrease in long-term survival compared with that of patients without diabetes (P = .0007). CONCLUSIONS: Patients with insulin-dependent diabetes mellitus undergoing cardiac surgery are at a greater risk of developing intraoperative myocardial acidosis/ischemia and of decreased survival postoperatively compared with patients without diabetes.

Use of a large bore syringe creates significantly fewer high intensity transient signals (HITS) into a cardiopulmonary bypass system than a small bore syringe.

INTRODUCTION: High intensity transient signals (HITS) have been reported to occur following perfusionist intervention during cardiac surgery. This study investigates the relationship of the syringe bore, injection rate, and HITS created. METHODS: Syringes (10 mL) with a male luer-lock connection (Large Bore) and Abboject 'jet syringes' with a 20 GA needle and male luer-lock connector (Small Bore) were filled with 10 mL of 0.9 N saline. A perfusionist was randomly assigned a set of four similar syringes followed by the other syringe bore. Each of the four syringes was injected into an in vitro saline-primed cardiopulmonary bypass (CPB) system over 5, 10, 15, or 20 sec. Sixteen randomizations of small and large bore syringes were completed at the four injection times (128 injections). HITS in the CPB arterial line were detected with transcranial Doppler (TCD) probes, were recorded for the 2 min following the injection, and were counted independently off-line by two reviewers. RESULTS: The use of a large bore syringe compared to a small bore syringe created significantly fewer HITS (29 +/- 6 versus 145 +/- 17 [mean +/- SEM], p<0.001) introduced into the CPB arterial line. Injection over a longer time produced significantly fewer HITS than shorter injection times (p<0.001). CONCLUSION: Significantly fewer HITS are introduced into the CPB system by using standard syringes and slower injection time.

Intracoronary shunt-induced endothelial cell damage in porcine heart.

BACKGROUND: Injury to and dysfunction of the endothelium can compromise the patency of coronary arteries and lead to impaired perfusion of the heart. Such injury can occur after the application of an intravascular shunt and/or a snare to a coronary artery during bypass surgery. In this study, multiphoton microscopy was used to assess the integrity of endothelium in porcine coronary arteries subjected to shunting and snaring during off-pump coronary artery bypass grafting (OPCAB). MATERIALS AND METHODS: In open chest porcine, the left anterior descending artery was manipulated in different regions using snare and shunt to simulate OPCAB. Sections of left anterior descending artery were labeled with fluorescent dyes to evaluate the viability of the endothelium. The structural integrity of the endothelium was evaluated by calcein- and ethidium homodimer-mediated fluorescence. Endothelial functional viability was assessed by measuring cellular esterase activity, calcium mobilization, and endothelial nitric oxide synthase-mediated generation of nitric oxide using fluorescence dyes and multiphoton microscopy. RESULTS: Substantial endothelial damage was observed in shunted region of the coronary arteries. In contrast, endothelium remained structurally viable in regions that were snared, similar to control regions of the coronary arteries that were not manipulated. Esterase activity, calcium mobilization, and nitric oxide generation was greater in the control and snared regions of the coronary arteries in comparison to the shunted region. CONCLUSIONS: The use of intracoronary shunts led to structural damage and attenuation of endothelial function in porcine coronary arteries, whereas snared vessels maintained their viability and integrity, similar to the control sections. The routine use of shunts in OPCABG may lead to endothelial damage and possibly to long-term graft failure.

Adverse 30-day outcomes after cardiac surgery: predictive role of intraoperative myocardial acidosis.

BACKGROUND: Regional myocardial acidosis in patients undergoing cardiac surgery has been shown to be reflective of regional myocardial ischemia. This study elucidates the relationship between intraoperative regional myocardial acidosis and 30-day postoperative outcomes after cardiac surgery. METHODS: Intramyocardial tissue pH in the anterior and posterior left ventricular walls was measured in 397 adult patients undergoing valve replacement or coronary revascularization surgery between 1987 and 2001. Dedicated nurses and research assistants prospectively collected preoperative, intraoperative, and outcomes data. Regional myocardial acidosis was defined in terms of pH thresholds identified by recursive partitioning. Adverse 30-day outcome, defined as death or any one of six complications, was the dependent variable in a multivariate logistic regression analysis. A morbidity score was developed on the basis of the sensitivity of each of the six complications in predicting death, and was the dependent variable in a multivariate linear regression analysis. RESULTS: During the period of aortic clamping, a mean intramyocardial tissue pH less than 6.85 was identified to be significant by recursive partitioning, and was encountered in either the anterior or posterior left ventricular wall in 85.4% of patients. After adjusting for preoperative and intraoperative variables, this pH threshold was found to be significantly associated with increased adverse outcomes within 30 days after surgery (p = 0.045). It was also significantly associated with increase in the morbidity score (p = 0.05). CONCLUSIONS: Regional myocardial acidosis of a magnitude frequently encountered during aortic clamping is an independent determinant of adverse 30-day outcomes after cardiac surgery. Its reversal by pH-guided myocardial management has the potential of improving postoperative patient outcomes.

Atherosclerosis is associated with delirium after coronary artery bypass graft surgery.

OBJECTIVES: To investigate whether atherosclerosis of the ascending aorta, internal carotid arteries, and coronary arteries is predictive of postoperative delirium in subjects undergoing coronary artery bypass graft (CABG) surgery. DESIGN: Prospective cohort study. SETTING: Boston Veterans Affairs Healthcare System. PARTICIPANTS: Thirty-six male veterans undergoing primary CABG surgery. MEASUREMENTS: Subjects underwent Duplex ultrasound to assess stenosis in the internal carotid arteries. Information on the ascending aortic plaque, as assessed by transesophageal echocardiogram, and the number of coronary vessels bypassed was collected. To create an atherosclerosis score, the number of atherosclerotic areas was added. A validated delirium battery was administered to the subjects preoperatively and on postoperative Days 2 and 5. RESULTS: Fifteen subjects (41.7%) developed delirium postoperatively. In bivariate analysis, carotid stenosis of 50% or more (relative risk (RR)=3.5, 95% confidence interval (CI)=1.5-8.1) and moderate-severe ascending aortic plaque (RR=2.9, 95% CI=1.0-8.5) were significantly associated with the development of delirium. There was a trend toward a significant association for three or more vessels bypassed (RR=9.6, 95% CI=0.6-145.3). After controlling for age, baseline cognition, and medical comorbidity, the atherosclerosis score was significantly associated with postoperative delirium (adjusted RR=2.7, 95% CI=1.1-6.8). CONCLUSION: In this preliminary report, atherosclerosis in the carotid arteries, aorta, and coronary circulation is associated with the development of delirium after CABG surgery. Further investigation into atherosclerosis as a risk factor for delirium is warranted.

Intraoperative regional myocardial acidosis and reduction in long-term survival after cardiac surgery.

BACKGROUND: Regional myocardial acidosis, as measured with tissue pH electrodes during cardiac surgery, has been shown to be reflective of regional myocardial ischemia. This study examined the relationship between intraoperative regional myocardial acidosis and long-term survival of patients undergoing cardiac surgery with cardiopulmonary bypass. METHODS: A total of 496 adult patients who underwent valve replacement, coronary artery revascularization, or both with intraoperative myocardial pH monitoring in the anterior and posterior left ventricular walls were followed up for 3 to 17 years (average 10.2 +/- 4.9 years) for all cause mortality. Regional myocardial acidosis in each patient was defined by the lower of the anterior and posterior wall pH values. RESULTS: A bivariate automatic interaction detection analysis identified three significant regional myocardial acidosis thresholds that affected long-term mortality: pH 37C less than 6.63 before aortic crossclamping, integrated mean pH 37C less than 6.34 during the period of aortic crossclamping, and pH 37C less than 6.73 at discontinuation of cardiopulmonary bypass. Cox proportional hazard regression analysis identified each of these thresholds to be independently determinant of survival, with pH 37C during aortic crossclamping having the highest risk ratio (risk ratio 2.15, 95% confidence interval 1.37-3.37). Raising pH 37C from lower than threshold before aortic crossclamping to higher than threshold during clamping increased the median survival by 40.2%. CONCLUSION: In adult patients undergoing cardiac surgery with cardiopulmonary bypass, regional myocardial ischemic acidosis before aortic crossclamping, during aortic crossclamping, and at discontinuation of cardiopulmonary bypass are independently associated with reduced long-term postoperative survival. Reversing or avoiding myocardial acidosis during cardiac surgery improves long-term patient survival.

Cardiopulmonary bypass: it's not the size, it's how you use it! Review of a comprehensive blood-conservation strategy.

Several of the manufacturers of cardiopulmonary bypass equipment have recently introduced new miniature cardiopulmonary bypass systems. New advancements in cardiopulmonary bypass technology are almost always of interest to the perfusion community. However, the question arises, what advantages do these systems offer over our present technology? The manufacturers claim that these new systems will add to our perfusion armamentarium by offering us an opportunity to further reduce priming volume and the surface area to which the blood is exposed. Our group, in the Department of Cardiac Surgery at Boston Medical Center has been involved in the development of a comprehensive blood conservation strategy since 1994. Our published data clearly demonstrates improved clinical outcomes using coated circuit technology as part of a comprehensive blood conservation strategy. In an effort to clearly evaluate this new technology, in this article we review our current technique at Boston Medical Center.

Intraoperative regional myocardial acidosis predicts the need for inotropic support in cardiac surgery.

OBJECTIVE: To determine the impact of regional myocardial acidosis encountered during cardiac surgery on the need for inotropic and intra-aortic balloon (IAB) support. METHODS: Intramyocardial tissue pH(37C) was measured in 247 patients undergoing cardiopulmonary bypass (CPB). Inotropic support (INO) was defined as requiring one or more of norepinephrine/epinephrine/amrinone/dobutamine/>2.5 mug/kg/min dopamine, for at least 45 minutes intraoperatively, and intraoperative or postoperative IAB use. PH (corrected to 37 degrees C, pH(37C)) during surgery was compared in patients who needed INO versus those who did not. Multivariate logistic regression models identified the determinants of INO. RESULTS: Fifty patients (20.2%) required INO intraoperatively. pH(37C) was significantly lower throughout reperfusion in patients needing INO. Preoperative ejection fraction and pH(37C) during reperfusion were identified as independent predictors of INO. CONCLUSIONS: This is the first study to show that intraoperative regional myocardial acidosis, a preventable condition, independently determines the need for intraoperative INO. Increased INO is associated with greater postoperative mortality and morbidity.

Determinants of regional myocardial acidosis during cardiac surgery.

BACKGROUND: Intraoperative regional myocardial acidosis (RMA) during cardiac surgery has been shown to be reflective of regional myocardial ischemia and an independent predictor of adverse postoperative outcomes. This study identifies the determinants of intraoperative RMA. METHODS: Intramyocardial tissue pH(37C) in the anterior and posterior LV walls was measured in 641 adult patients during cardiac surgery. RMA at two intraoperative periods was quantified as integrated mean pH(37C) < 6.35 during aortic clamping (AC) and pH(37C) < 6.73 at the end of cardiopulmonary bypass (CPB). These pH thresholds were chosen because of their demonstrated relationship to long-term patient survival. Multivariate logistic regression models were constructed. An acidosis prediction score was constructed based on the factors determining RMA at the end of CPB. RESULTS: Independent determinants of RMA during AC were preoperative New York Heart Association class III/IV (P = .007), current smoker (P = .0088), pH(37C) < 6.63 prior to AC (P < .0001), and intraoperative myocardial management technique (P = .0001). Independent determinants of RMA at end of CPB were ASA class IV/V (P = .0042), pH(37C) < 6.63 prior to AC (P = .035), pH(37C) < 6.35 during AC (P = .001), and total duration of CPB > or = 212 minutes (P = .001). CONCLUSIONS: RMA during cardiac surgery is determined by patient risk factors, the magnitude of preceding regional myocardial acidosis, and the duration of CPB.

Acidosis-induced apoptosis in human and porcine heart.

BACKGROUND: Acidosis-mediated injury to cardiac myocytes during surgery may lead to progressive heart failure. The nature of this injury, although not well defined, may be caused by induction of apoptosis in cardiac myocytes. We applied fluorescence imaging and biochemical techniques to assess apoptosis in cardiac myocytes excised from human patients and porcine subjects maintained on cardiopulmonary bypass to demonstrate the relationship between acidosis and apoptosis. METHODS: Multiphoton microscopy was used to image fluorescence signals generated in myocytes deep within atrial and ventricular biopsies for identification of apoptotic changes. The biopsies, obtained during cardiac surgery, were subjected to ex vivo or in vivo acidosis. Proapoptotic markers such as exposure of phosphatidyl serine, cytochrome c, apoptotic protease-activating factor-1, and caspase-3 were identified using fluorescence-based imaging and biochemical assays. RESULTS: Within 30 minutes of storage in low pH (<7) buffers, apoptosis was detected in human atrial samples, the severity of which correlated well with low pH. Apoptosis was also detected in atrial and ventricular biopsy samples obtained from three porcine subjects maintained on cardiopulmonary bypass and undergoing 110 minutes of aortic cross-clamp and 10 minutes of reperfusion, in which the cardiac pH was 6.36, 7.14, and 7.48. The apoptosis level detected in postacidotic reperfused cardiac tissue was pH dependent and approximately threefold greater than the precross-clamp levels. CONCLUSIONS: Using fluorescence multiphoton microscopy and biochemical techniques we have assessed a direct correlation between low pH and induction of apoptosis in cardiac samples obtained both from human patients undergoing cardiac surgery and porcine subjects maintained on cardiopulmonary bypass simulating cardiac surgery.

Heparin-bonded circuits without a cardiotomy: a description of a minimally invasive technique of cardiopulmonary bypass.

The deleterious effects of cardiotomy suction have been well recognized and well documented for some time. The use of cardiotomy suction results in the exposure of blood to the defoaming sock, aspiration of stagnant pericardial blood into the systemic circulation, and the entrainment of both fatty and gaseous microemboli. The purpose of this paper is to describe a technique using heparin-bonded cardiopulmonary circuits (HBCs) without the use of a cardiotomy reservoir or cardiotomy suction. Our group has previously demonstrated improved clinical outcomes using HBCs and a low-dose anti-coagulation protocol. It is our goal to further improve clinical outcomes and further attenuate the deleterious effects of cardiopulmonary bypass by eliminating the potential complications attributed to the use of cardiotomy suction.