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.

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.

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.

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.