Subnormothermic preservation in somah: a novel approach for enhanced functional resuscitation of donor hearts for transplant.

Organ preservation at 4°C results in temporally irreversible injury to cellular structure and function. This study was designed to evaluate the possibility of storing hearts at ambient temperatures in novel organ preservation solution Somah to prevent damage and preserve optimum function by maintaining cellular energy over the temperature range of storage. Porcine hearts were stored in Celsior at 4°C and Somah at 4°C, 13°C and 21°C for 5 h thereafter reperfused and reanimated in vitro for 3 h. Heart weights, histopathology, ultrastructure and 2-dimensional echocardiography (2D-Echo) assessments showed preservation of structure in Somah groups. Tissue high-energy phosphate levels in Somah groups after storage were significantly greater than the Celsior hearts (p < 0.05) and highest in the 21°C Somah hearts. Upon reperfusion, myocardial O2 consumption and lactate levels quickly achieved steady state in 21°C hearts, but were delayed in Somah 4/13°C groups and severely depressed in the Celsior group. Inotrope and electroconversion requirements were inversely related to storage temperature. In vitro 2D Echo demonstrated a discordantly attenuated function in the Celsior group, moderate functionality in 4°C Somah group and superior reestablishment of performance in the Somah higher temperature groups. Hearts stored in Somah at 21°C were metabolically and functionally superior to any other groups.

Technique for routine use of heparin bonded circuits with a reduced anticoagulation protocol.

The use of heparin-bonded cardiopulmonary bypass circuits (HBCs) with reduced anticoagulation protocol during cardiac surgery attenuates some of the adverse pathophysiologic responses to cardiopulmonary bypass (CPB). The strategies of how to maximize improvements in clinical outcomes using this technique are still debated. This article describes in detail a comprehensive approach to strategies developed at Boston Medical Center and the West Roxbury Veteran Affairs Medical Center in over 4000 cases in which HBC with a reduced anticoagulation protocol is used routinely. Important elements of this technique include elimination of cardiotomy reservoir during coronary artery bypass graft surgery (CABG), autologous blood priming, normothermic CPB, and precise heparin and protamine titration. Adaptation and variation in this technique to specific clinical situations is also highlighted.

Decreased incidence of arterial thrombosis using heparin-bonded intraaortic balloons.

BACKGROUND: This experimental study sought to determine whether heparin-bonding of intraaortic balloons (IAB) would decrease the incidence of arterial thrombosis in the absence of systemic heparinization. METHODS: In 25 adult pigs, a 9F, 40-mL IAB was inserted into the femoral artery and positioned just below the takeoff of the left subclavian artery for 9 hours. Five animals received systemic heparin, 10 animals had no heparin, and another 10 animals received no heparin but the IAB was heparin-bonded (Duraflo II). Thrombus formation was assessed using a numerical scoring system (0 = no thrombosis to 3 = thrombus >5 cm or evidence of luminal compromise). RESULTS: Animals receiving heparin and heparin-bonded IAB had no thrombus formation around the IAB (mean +/- SE; 0 +/- 0.00 heparin versus 1.55 +/- 0.29 no heparin versus 0 +/- 0.00 heparin-bonded; p < 0.005), at the insertion site (0 +/- 0.00 heparin versus 1.55 +/- 0.29 no heparin versus 0 +/- 0.0 heparin-bonded; p < 0.005), and in the distal femoral artery (0 +/- 0.00 heparin versus 2.00 +/- 0.23 no heparin versus 0 +/- 0.00 heparin-bonded; p < 0.005). CONCLUSIONS: Heparin-bonding of the IAB significantly decreases thrombus formation in the absence of systemic heparinization.

Reduction of allogeneic blood transfusions after open heart operations by lowering cardiopulmonary bypass prime volume.

BACKGROUND: Despite recent advances in blood conservation techniques, up to 30% to 80% of patients undergoing open heart operations require allogeneic blood transfusions. A prospective, randomized study was performed to test the effect of lowering cardiopulmonary bypass prime volume (as an additional component of an integrated blood conservation strategy) on clinical outcome and allogeneic blood transfusion. METHODS: One hundred fourteen patients undergoing open heart operations were randomized to either full prime (FP) volume (1,400 mL of Plasmalyte solution) or reduced prime (RP) volume (600 to 800 mL). The reduction of prime volume was achieved by slowly draining the cardiopulmonary bypass circuit into a cell-saving device before the initiation of bypass. Firm transfusion thresholds were observed. RESULTS: There were no significant differences between the groups with respect to baseline characteristics, body surface area, type and urgency of the procedures, perfusion technique, and hematologic profile. Mortality (FP, 1.7%; RP, 0%; p approximately 1.0) and overall morbidity (FP, 28.1%; RP, 22.8%; p = 0.53) were similar. However, transfusion requirements were significantly lower in the RP group: total donor exposure, 3.8 +/- 10.1 versus 1.0 +/- 2.4 units (p = 0.044); percentage of patients transfused, 54% (n = 31) versus 35% (n = 20) (p = 0.036). Twenty-four-hour chest tube drainage was similar: 455 +/- 223 mL for FP versus 472 +/- 173 mL for RP (p = 0.66). The lowest hematocrit on bypass was significantly higher in the RP group: 29.3% +/- 4% versus 26.3% +/- 5.3% (p = 0.009). CONCLUSIONS: Lowering cardiopulmonary bypass prime volume resulted in a significant decrease in allogeneic blood product use. Because postoperative 24-hour chest tube drainage was similar in both groups, and hematocrit during bypass was higher in the RP group, the reduction in allogeneic blood transfusions appears to be related to a decrease in prime-induced hemodilution. This technique is effective, simple, and safe. It therefore should be strongly considered for patients undergoing operations using normothermic or near-normothermic cardiopulmonary bypass who are at high risk for allogeneic blood transfusion.

Effect of anticoagulation protocol on outcome in patients undergoing CABG with heparin-bonded cardiopulmonary bypass circuits.

BACKGROUND: We have demonstrated that the use of heparin-bonded cardiopulmonary bypass circuits (HBCs) combined with a lower anticoagulation protocol as an adjunct to an integrated blood conservation strategy decreases the incidence and magnitude of homologous transfusion and improves clinical outcome in patients undergoing primary coronary artery bypass grafting. It is not known whether it is the lower anticoagulation protocol that influences outcome in patients treated with HBCs. Furthermore, the thrombogenic risk of using lower anticoagulation with HBCs still is debated. METHODS: To answer these questions, a prospective randomized study was conducted in which 244 patients undergoing primary coronary artery bypass grafting were treated with HBCs and randomized to undergo either a full (activated clotting time, > 450 seconds) or a lower (activated clotting time, > 250 seconds) anticoagulation protocol. In addition to clinical outcome, levels of thrombin generation markers during and after cardiopulmonary bypass were assessed in a consecutive subset of 58 patients (full anticoagulation profile = 28, lower anticoagulation profile = 30) by measuring thrombin-antithrombin complexes and prothrombin fragment 1.2. Levels of these markers also were correlated with the activated clotting time during cardiopulmonary bypass. RESULTS: Preoperative and intraoperative risk profiles and other characteristics were similar in both groups, with more than 60% of patients undergoing nonelective operation. Compared with the full anticoagulation protocol group, patients in the lower anticoagulation protocol group were less likely to require blood products (24.2% versus 35.8%, respectively; p = 0.047) and received substantially fewer homologous donor units (0.50 +/- 0.92 versus 1.08 +/- 2.10 U, respectively; p = 0.005). Clinical outcomes were uniformly outstanding (but similar) in both treatment groups, with a modest reduction in the length of the hospital stay in the lower anticoagulation protocol group (5.26 +/- 1.23 versus 5.63 +/- 1.73 days, respectively; p = 0.05). The use of HBCs with a lower anticoagulation protocol was not associated with any adverse clinical events. Thrombin generation increased during cardiopulmonary bypass in both treatment groups, but was unrelated to the anticoagulation protocol or the activated clotting time (r2 = 0.03). No differences between the full and lower anticoagulation protocol groups were noted in the number of microemboli detected by transcranial Doppler analyses during cardiopulmonary bypass (n = 40) or in the postoperative neurologic and neuropsychologic outcomes (n = 30). CONCLUSIONS: This study definitively demonstrates that, when used appropriately, patients who are treated with HBCs and a lower anticoagulation protocol have a lower incidence and magnitude of homologous transfusion and are not at any added risk for clinical, hematologic (thrombin-antithrombin complex and fragment 1.2 measurements), or microscopic (transcranial Doppler analyses) thromboembolic complications or for neurologic or neuropsychologic deficits.

Heparin-bonded circuits decrease myocardial ischemic damage: an experimental study.

BACKGROUND: Heparin-bonded cardiopulmonary bypass circuits reduce complement activation, but their effect on myocardial function is unknown. This study was undertaken to determine whether heparin-bonded circuits reduce myocardial damage during acute surgical revascularization. METHODS: In 16 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 45 minutes of cardioplegic arrest and 180 minutes of reperfusion with the snares released. During the period of coronary occlusion, all animals were placed on percutaneous bypass followed by standard cardiopulmonary bypass during the periods of cardioplegic arrest and reperfusion. In 8 pigs, heparin-bonded circuits were used, whereas 8 other pigs received nonbonded circuits. RESULTS: Animals treated with heparin-bonded circuits had the best preservation of wall motion scores (3.5 +/- 0.3 versus 2.3 +/- 0.2; 4 = normal to -1 = dyskinesis; p < 0.05), least tissue acidosis (change in pH = -0.31 +/- 0.02 versus -0.64 +/- 0.08; p < 0.05), smallest increase in lung H2O (1.7% +/- 0.7% versus 6.1% +/- .5%; p < 0.05), and the lowest area of necrosis/area of risk (20.3% +/- 2.2% versus 40.4% +/- 1.6%; p < 0.05). CONCLUSIONS: We conclude that heparin-bonded circuits significantly decrease myocardial ischemic damage during acute surgical revascularization.

Heparin-bonded circuits improve clinical outcomes in emergency coronary artery bypass grafting.

Compared to patients undergoing elective or urgent coronary artery bypass grafting (CABG), those undergoing emergency CABG (EM-CABG) have a higher morbidity and mortality. The use of heparin-bonded circuits (HBC) has been shown to improve clinical outcomes in nonemergent CABG patients. It is not known, however, whether the improved hemostasis and attenuation of the inflammatory response to cardiopulmonary bypass, conferred by HBC, can overcome the high incidence of comorbid risk factors in (EM-CABG) patients and improve their outcomes. A retrospective analysis of 206 consecutive patients undergoing EM-CABG over 4 years (1993-1997) at one institution was performed. Eighty-one patients were treated with conventional non-heparin-bonded circuits (NHBC) with full anticoagulation protocol (FAP, activated clotting time [ACT] > 480 sec); 125 patients were treated with HBC and a lower anticoagulation protocol (LAP, ACT > 280 seconds). Outcomes and results were collected prospectively and are presented as mean +/- SD. Preoperative risk profiles were similar in both treatment groups. Postoperatively, compared with the NHBC group, patients treated with HBC/LAP required fewer homologous donor units (4.1 +/- 10.7 vs 8.2 +/- 13.6 units, p = 0.005), were less likely to require inotropic support (18.6% vs 38.3%, p = 0.005), and had a lower incidence of perioperative myocardial infarction (MI, 3.2% vs 12.3%, p = 0.04) and pulmonary complications (4.0% vs 12.3%, p = 0.04). The use of HBC/LAP resulted in a decreased incidence of postoperative complications (12.8% vs 28.4%, p = 0.01, odds ratio 0.37 with 95% confidence interval [CI] 0.18-0.76). This resulted in a shorter duration of ventilatory support (30.5 +/- 54.0 vs 72.8 +/- 16.7 hours, p = 0.009), ICU stay (38.2 +/- 36.5 vs 91.5 +/- 68.7 hours, p = 0.009), hospital stay (8.0 +/- 7.1 vs 11.0 +/- 8.9 days, p = 0.008), and therefore cost. In conclusion, the use of HBC/LAP in EM-CABG resulted in a reduction of homologous transfusion and postoperative complications associated with decreased hospital stays and cost.

Heparin-bonded circuits with a reduced anticoagulation protocol in primary CABG: a prospective, randomized study.

BACKGROUND: A substantial proportion of patients undergoing primary coronary revascularization require homologous transfusions. To address this problem, a comprehensive strategy to diminish perioperative blood loss was developed. METHODS: A prospective randomized trial was undertaken to test the hypothesis that "tip-to-tip" heparin-bonded cardiopulmonary bypass circuits (HBC) can further enhance blood conservation and clinical outcomes in patients undergoing primary coronary artery bypass grafting. Two hundred thirty-four patients were treated with either HBC and lower anticoagulation therapy (activated clotting time > 280 seconds) or with conventional, nonheparin-bonded circuits and full anticoagulation therapy (activated clotting time > 480 seconds). RESULTS: Preoperative and intraoperative risk profiles and characteristics were similar in both groups, with 69.7% of the patients undergoing nonelective coronary artery bypass grafting. Compared with the group with nonheparin-bonded circuits, patients treated with HBC had a lower chest tube output in the first 24 hours (561 +/- 257 versus 651 +/- 403; p = 0.04), were less likely to receive blood products (31.6% versus 47.9%; p = 0.01), and required substantially fewer homologous donor units (1.98 +/- 4.8 versus 4.29 +/- 10.1; p = 0.029). Patients treated with HBC required a shorter duration of ventilatory support (13.2 +/- 16.9 versus 23.4 +/- 50.0 hours; p = 0.04), spent less time in the surgical intensive care unit (20.7 +/- 17.4 versus 35.5 +/- 61.7 hours; p = 0.01), spent fewer days in the hospital (6.0 +/- 2.5 versus 7.3 +/- 5.2 days; p = 0.02), and had fewer postoperative complications (25.6% versus 39.3%; p = 0.03). The use of HBC with a lower anticoagulation protocol was not associated with any adverse events. CONCLUSIONS: This study demonstrates that the use of HBC with a lower anticoagulation protocol in primary coronary artery bypass grafting safely and effectively reduces the incidence and magnitude of homologous transfusion, the duration of ventilation, and surgical intensive care unit and hospital stays.

Enhanced blood conservation in primary coronary artery bypass surgery using heparin-bonded circuits with lower anticoagulation.

BACKGROUND: Despite many advances in blood conservation techniques, a significant proportion of patients undergoing primary coronary revascularization still require homologous transfusions. A comprehensive strategy to diminish perioperative blood loss was developed by integrating many individual components to create an improved blood conservation environment and was prospectively applied to 557 patients undergoing primary coronary artery bypass grafting (CABG) procedures performed in our medical center over a 14-month period. METHODS: The first 455 patients were treated with conventional, nonheparinbonded circuits (NHBCs) and full anticoagulation (activated clotting time [ACT] > 480 sec). We wanted to test the hypothesis of whether "tip-to-tip" heparin-bonded circuits (HBCs) used in conjunction with lower anticoagulation (ACT > 280 sec) when added to our current blood conservation environment can further enhance clinical outcomes. We prospectively applied this technique to a consecutive group of patients (n = 102). RESULTS: Compared to patients treated with NHBCs, patients treated with HBCs had a significantly lower mediastinal and pleural chest tube output in the first 24 hours (683 +/- 561 mL vs 984 +/- 616 mL, p < 0.00001) were less likely to be transfused (52% vs 68.1%, p < 0.01) and had a lower exposure to different blood donor units (4.1 +/- 8.4 vs 9.3 +/- 10.3, p < 0.000003). There were no complications directly related to HBCs used in conjunction with lower anticoagulation. Morbidity and mortality rates were similar in both treatment groups. CONCLUSION: In summary, HBCs in conjunction with lower anticoagulation were safely applied in patients undergoing primary CABG with marked improvement in blood conservation, and should be considered for broader clinical use.

Effective use of heparin-bonded circuits and lower anticoagulation for coronary artery bypass grafting in Jehovah's Witnesses.

Despite many advances in blood conservation techniques, a significant proportion of patients undergoing primary coronary revascularization still require homologous transfusions. Based on a large clinical experience with high-risk patients during coronary artery bypass, a comprehensive strategy to diminish perioperative blood loss was developed by integrating many individual components. An integral component in this strategy is the use of lower heparinization (activated clotting time [ACT] > 280 sec) in conjunction with "tip-to-tip" heparin-bonded cardiopulmonary bypass (CPB) circuits (HBC). This technique was prospectively applied to a group of Jehovah's Witnesses (JW) patients who refuse blood transfusion on religious grounds (n = 9). Outcome was compared to a matched group of patients treated with full heparinization (ACT > 480 sec) used with conventional, nonheparin-bonded CPB circuits (NHBC) performed within the same academic year (n = 455). There were no complications in JW patients who had a significantly lower mediastinal and pleural tube output in the first 24 hours (323 67 mL vs 984 616 mL, p < 0.01). In comparison to JW patients who received no transfusions, 68.1% of patients treated with NHBC were transfused (p 0.0001). In summary, HBC in conjunction with lower anticoagulation was effectively and safely applied to JW patients undergoing coronary artery bypass grafting. This technique should be considered for broader clinical use.

Role of leukocyte depletion during cardiopulmonary bypass and cardioplegic arrest.

BACKGROUND: Leukocyte depletion (LD) has been shown to be beneficial during the reperfusion of acutely ischemic myocardium; however, its role during cardiopulmonary bypass (CPB) in hearts protected with blood cardioplegia (BCP) is unknown. This experimental study sought to determine whether LD filters inserted in the CPB circuit before cardioplegic arrest and in the BCP circuit during arrest would decrease ischemic myocardial damage. METHODS: In 20 pigs, the second and third diagonal vessels were occluded for 90 minutes, followed by 45 minutes of BCP arrest and 180 minutes of reperfusion on CPB. In 5 pigs, LD filters were inserted in both the CPB and BCP circuits (LD-CPB+BCP). Five pigs had LD during BCP (LD-BCP), 5 pigs had LD during CPB (LD-CPB), and 5 pigs had no LD. Ischemic damage was assessed by wall motion scores using two-dimensional echocardiography and the area of necrosis/area of risk. RESULTS: The LD-CPB and LD-CPB+BCP groups had the highest wall motion scores and the lowest area of necrosis/area of risk. The addition of LD to BCP alone did not significantly alter wall motion scores or the area of necrosis/area of risk. CONCLUSION: Leukocyte depletion filters significantly reduce ischemic damage during acute surgical revascularization and appear to be most effective when placed in the CPB circuit before cardioplegic arrest.

Combining percutaneous bypass with coronary retroperfusion limits myocardial necrosis.

After an acute coronary occlusion that results in hemodynamic instability, the institution of percutaneous bypass (PB) can effectively support the failing myocardium. However, PB cannot augment coronary blood flow, and substantial regional myocardial necrosis can still occur. This experimental study was undertaken to determine whether combining PB with coronary venous retroperfusion using pressure-controlled intermittent coronary sinus occlusion (PICSO) would limit myocardial necrosis after an acute coronary occlusion. In 30 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 30 minutes of cardioplegic arrest and 180 minutes of reperfusion with the snares released. During the period of coronary occlusion, 10 pigs were placed on PB, 10 pigs received PB+PICSO, and 10 pigs received no support (unmodified). Hearts treated with the combination of PB+PICSO had the highest wall motion scores (unmodified, 1.4 +/- 0.3; PB, 1.4 +/- 0.3; PB+PICSO, 2.8 +/- 0.3 [p < 0.05 versus unmodified and PB]) and the lowest area of necrosis in the area at risk (unmodified, 73% +/- 3%; PB, 43% +/- 2%; PB+PICSO, 14% +/- 2% [p < 0.05, PB and PB+PICSO versus unmodified; p < 0.05, PB+PICSO versus PB]). We conclude that combining PB with coronary venous retroperfusion significantly limits myocardial necrosis.

Intraoperative assessment of the stunned versus infarcted myocardium with the simultaneous use of transesophageal echocardiography and the measurement of myocardial pH: two case studies.

The ability to differentiate intraoperatively between myocardial stunning, which is reversible, and irreversible myocardial infarction has major implications because it provides a rational approach to the use or withholding of ventricular assist devices in patients with severe postcardiotomy ventricular dysfunction. Two illustrative cases are presented.

Enhanced recovery of ischemic myocardium by combining percutaneous bypass with intraaortic balloon pump support.

Although percutaneous bypass (PB) can support the failing myocardium, regional ischemic damage may still occur beyond a coronary occlusion. This study sought to determine whether the addition of intraaortic balloon pump (IABP) support to PB would result in more optimal salvage of ischemic myocardium. In 30 pigs, the second and third diagonal vessels were occluded with snares for 90 minutes followed by 30 minutes of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary artery occlusion, 10 pigs were placed on PB, 10 pigs received PB plus IABP support, and 10 pigs received no support (the unmodified group). The hearts treated with the combination of PB and IABP support exhibited the highest wall motion scores (3.3 +/- 0.20 for the PB plus IABP group [p < 0.05 from the unmodified group and from the PB group]; versus 1.40 +/- 0.30 for the PB group versus 1.37 +/- 0.33 for the unmodified group), the least tissue acidosis (change in pH, -0.30 +/- 0.2 for the PB plus IABP group [p < 0.05 from the PB group] versus -0.60 +/- 0.10 for the PB group versus -0.41 +/- 0.13 for the unmodified group), and the least area of necrosis (25% +/- 5% for the PB plus IABP group [p < 0.05 from the unmodified group and from the PB group]; versus 43% +/- 2% for the PB group [p < 0.05 from the unmodified group] versus 73% +/- 3% for the unmodified group).(ABSTRACT TRUNCATED AT 250 WORDS)

Detrimental effects of interrupting warm blood cardioplegia during coronary revascularization.

Warm blood cardioplegia has emerged as a substitute for cold blood cardioplegia as a method of myocardial protection. However, the continuous infusion of blood in this technique may obscure the operative field and necessitate interruption of warm blood cardioplegia. This experimental study was therefore undertaken to determine whether interrupting warm blood cardioplegia during coronary revascularization would increase myocardial damage. In 30 adult pigs, the second and third diagonal vessels were occluded with snares for 90 minutes. All animals underwent cardiopulmonary bypass and 45 minutes of cardioplegic arrest. During the period of cardioplegic arrest, 10 pigs received intermittent antegrade/retrograde infusion of cold blood cardioplegic solution (4 degrees C) 10 pigs received continuous retrograde infusion of warm blood cardioplegic solution (37 degrees C) at 100 ml/min, and 10 pigs received retrograde infusion of warm blood cardioplegic solution that was interrupted for three 7-minute periods. After aortic unclamping, the coronary snares were released and all hearts were reperfused for 180 minutes. Interrupting retrograde warm blood cardioplegia resulted in more tissue acidosis during cardioplegic arrest (6.20 +/- 0.16 interrupted retrograde warm blood cardioplegia and 6.45 +/- 0.12 continuous retrograde warm blood cardioplegia, both p < 0.05 compared with 6.98 +/- 0.17 intermittent antegrade and retrograde cold blood cardioplegia), decreased echocardiographic wall-motion scores (4 [normal] to -1 [dyskinesis]; 2.06 +/- 0.30 interrupted retrograde warm blood cardioplegia, p < 0.05 compared with 3.30 +/- 0.40 intermittent antegrade and retrograde cold blood cardioplegia, 2.80 +/- 0.40 continuous retrograde warm blood cardioplegia), and increased tissue necrosis as measured by the area of necrosis/area at risk (38% +/- 5% interrupted retrograde warm blood cardioplegia, p < 0.05 compared with 21% +/- 2% intermittent antegrade and retrograde cold blood cardioplegia; 25% +/- 2% continuous retrograde warm blood cardioplegia). We concluded that interrupting warm blood cardioplegia during coronary revascularization diminishes the effectiveness of warm blood cardioplegia and results in increased ischemic damage.

Warm versus cold blood cardioplegia--is there a difference?

This experimental study sought to compare the effectiveness of warm blood cardioplegia versus cold blood cardioplegia in protecting areas of ischemic myocardium during urgent coronary revascularization. In 40 adult pigs, the second and third diagonal vessels were occluded with snares for 90 minutes. All animals were then placed on cardiopulmonary bypass and underwent 45 minutes of cardioplegic arrest followed by 3 hours of reperfusion during which time the coronary snares were released. During the period of cardioplegic arrest, 10 pigs received antegrade continuous warm blood cardioplegic solution (37 degrees C) at 100 ml/min; 10 animals received retrograde warm blood cardioplegic solution at 100 ml/min; 10 received intermittent, antegrade cold blood cardioplegic solution (4 degrees C), and 10 animals received intermittent, antegrade/retrograde cold blood cardioplegic solution. Hearts protected with antegrade warm blood cardioplegic solution had the lowest pH values in the area at risk (6.59 +/- 0.10 antegrade warm blood cardioplegia versus 6.80 +/- 0.10 retrograde warm blood cardioplegia versus 6.72 +/- 0.18 antegrade cold blood cardioplegia versus 6.85 +/- 0.15 antegrade/retrograde cold blood cardioplegia and the highest area of necrosis (42% +/- 3% antegrade warm blood cardioplegia versus 26% +/- 2% [p < 0.05 from antegrade warm blood cardioplegia] retrograde warm blood cardioplegia versus 31% +/- 2% [p < 0.05 from antegrade warm blood cardioplegia] antegrade cold blood cardioplegia versus 21% +/- 2% [p < 0.05 from antegrade warm blood cardioplegia] antegrade/retrograde cold blood cardioplegia). We conclude that in the presence of an acute coronary occlusion with ischemic myocardium, warm blood cardioplegic solution should be given in a continuous retrograde fashion and does not result in myocardial protection superior to the protection that can be achieved with antegrade/retrograde cold blood cardioplegic solution.

Retroperfusion and balloon support to improve coronary revascularization.

Coronary venous retroperfusion and Intra-Aortic Balloon Pump (IABP) support are methods currently utilized to reduce ischemic damage prior to revascularization of acutely ischemic myocardium. This study was undertaken to determine whether combining coronary venous retroperfusion using Pressure Controlled Intermittent Coronary Sinus Occlusion (PICSO) with the IABP would result in improved salvage of ischemic myocardium. In 40 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours followed by 1/2 hours of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion prior to arrest, 10 pigs received the IABP, 10 had PICSO, 10 had PICSO+IABP, while 10 had no intervention (Unmodified). Ischemic damage was assessed by echocardiographic wall motion scores, myocardial pH, and the area of necrosis/area of risk using histochemical staining. Both PICSO and the IABP alone significantly reduced ischemic damage. However, the best wall motion scores, highest pH, and least necrosis was seen in the IABP+PICSO group. We conclude that the combination of coronary venous retroperfusion using PICSO and the IABP results in the most optimal recovery of acutely ischemic myocardium during emergent surgical revascularization.

Role of percutaneous bypass in reducing infarct size after revascularization for acute coronary insufficiency.

This study compares the effectiveness of percutaneous bypass (PB) with that of the intra-aortic balloon pump (IABP) in reducing infarct size and ischemic damage after revascularization for acute coronary occlusion. In 30 adult pigs, the second and third diagonal vessels were occluded with snares for 1 1/2 hours, followed by 1/2 hour of cardioplegic arrest and 3 hours of reperfusion with the snares released. During the period of coronary occlusion before the institution of cardiopulmonary bypass, 10 pigs were placed on PB, 10 pigs received IABP, and 10 others received no intervention (unmodified). Ischemic damage in the area at risk was assessed by echo wall motion scores (ranging from 4 indicating normal to -1 indicating dyskinesia), changes in myocardial tissue pH (delta pH) from preischemia, and the area of necrosis/area of risk (AN/AR) ratio. Hearts treated with the IABP had the highest wall motion scores (1.27 +/- 0.33 for unmodified versus 1.40 +/- 0.30 for PB versus 2.04 +/- 0.30 for IABP), the least change in pH values from preischemia (delta pH: 0.41 +/- 0.13 for unmodified versus 0.60 +/- 0.10 for PB versus 0.25 +/- 0.09 for IABP, p less than 0.05 for IABP versus PB), and the least amount of myocardial necrosis (AN/AR ratio: 73 +/- 4% for unmodified versus 43 +/- 2 for PB versus 27 +/- 4 for IABP, p less than 0.05 for PB and IABP versus unmodified and for IABP versus PB). Although the PB group experienced less myocardial necrosis than did the unmodified group, the most optimal recovery occurred in the IABP group.