Mohr R

Primary coronary artery bypass grafting without cardiopulmonary bypass in impaired left ventricular function

BACKGROUNDnConventional coronary artery bypass grafting using cardiopulmonary bypass carries relatively high mortality and morbidity for patients with left ventricular dysfunction.nnnMETHODSnSeventy-five patients with ejection fraction less than or equal to 0.35 underwent primary coronary artery bypass grafting without cardiopulmonary bypass between December 1991 and December 1994. Thirty-two patients (43%) had congestive heart failure, 11 (15%) were referred for operation within the first 24 hours of evolving myocardial infarction, and 21 (28%) up to 1 week after acute myocardial infarction. Eighteen patients (24%), 6 of whom were in cardiogenic shock, underwent emergency operations.nnnRESULTSnMean number of grafts/patient was 1.9 (range, 1 to 4), and internal mammary artery was used in 66 patients (85%). Only 17 patients (23%) received a graft to a circumflex marginal artery. Two patients (2.7%) died perioperatively, and 1 (1.3%) sustained stroke. At mean follow-up of 28 months, 13 patients had died, and angina had returned in 7 (10.5%). One- and four-year actuarial survival was 96% and 73%, respectively.nnnCONCLUSIONSnCoronary artery bypass grafting without cardiopulmonary bypass is a viable alternative to conventional coronary artery bypass grafting particularly for patients with extreme left ventricular dysfunction or those with coexisting risk factors, such as acute myocardial infarction and cardiogenic shock.

Comparison of myocardial revascularization without cardiopulmonary bypass to standard open heart technique in patients with left ventricular dysfunction.

OBJECTIVEnTo compare myocardial revascularization without cardiopulmonary bypass to standard open heart technique in patients with left ventricular (LV) dysfunction.nnnMETHODSn117 patients with LV dysfunction (ejection fraction (EF) < 35%) underwent coronary artery bypass surgery between January 1991 and July 1994. Sixty-four (group A) were operated on without a cardiopulmonary bypass, and 53 (group B) with one. Prevalence of EF < 20% (17 vs. 6%) and emergency operations (22 vs. 7%, P = 0.03) was higher in group A. The average number of grafts was 1.9 +/- 0.8/pt in group A and 3.5 +/- 0.9/pt in group B (P < 0.01), and the internal mammary artery was used in 54 (84%) and 42 (79%) patients, respectively. Only 16 patients (25%) in group A received a graft to a circumflex marginal artery compared to 51 (96%) in group B (P < 0.0001).nnnRESULTSnTwo patients (3.1%) died perioperatively in group A compared to 7 (13%) in group B (P = NS). In two patients from group A (3.1%) and in four (7.5%) from group B intra-aortic balloon pump was inserted postoperatively (P = NS). One year actuarial survival was 91 and 79% (P = 0.03) and 2-year survival was 86 and 65% (P = 0.04), respectively. Return of angina occurred in five (8%) and three (6%) patients (P = NS).nnnCONCLUSIONSnThese results show a trend for lower operative risk resulting in better overall survival in selected patients with LV dysfunction undergoing coronary artery bypass surgery without cardiopulmonary bypass.

Fresh blood units contain large potent platelets that improve hemostasis after open heart operations

Twenty units of fresh whole blood were separated into fresh packed red blood cells (PC) and platelet-rich plasma (PRP) and were transfused to 40 patients immediately after coronary bypass grafting. Patients were preoperatively randomized to receive either PRP (group A, 20 patients) or PC (group B, 20 patients). Platelet number in the PRP group was greater, but not significantly greater, than in the PC group (7.5 +/- 3 versus 5.9 +/- 2.2 x 10(10); p = not significant). However, mean platelet volume in the PC group was significantly greater (8.75 +/- 1.1 versus 6 +/- 0.7 fL). Postoperatively, group A patients bled more than group B (566 +/- 164 versus 327 +/- 41 mL; p less than 0.01) and received more red blood cell units (2.7 +/- 1.2 versus 1.6 +/- 0.7 U; p less than 0.05) and a larger number of blood products (5.9 +/- 3.7 versus 2.6 +/- 1.2 U; p less than 0.05). Transfusion of PRP to group A increased platelet count from 128 +/- 20 to 148 +/- 110 x 10(9)/L; however, platelet functions did not improve. Administration of PC to group B increased platelet count from 139 +/- 22 to 156 +/- 23 x 10(9)/L, improved platelet aggregation (with collagen from 33% +/- 20% to 53% +/- 23%, with epinephrine from 36% +/- 24% to 51% +/- 20%; p less than 0.05), and corrected the prolonged bleeding time. The results suggest that the improved hemostasis observed after fresh whole blood administration is related to the large, potent platelets that remained in the PC and were not separated to the PRP during standard platelet concentrate preparation.

Reoperative coronary artery bypass without cardiopulmonary bypass

BACKGROUNDnConventional reoperative coronary artery bypass grafting using cardiopulmonary bypass carries relatively high mortality and morbidity.nnnMETHODSnSeventy-seven patients underwent coronary artery bypass grafting without cardiopulmonary bypass in two centers between 1988 and 1994. Mean age was 65 +/- 8 years (mean +/- SD). Twenty-three (30%) were operated on urgently and 7 (9%) emergently. Nine (12%) were referred for operation up to 2 weeks after acute myocardial infarction. Fifteen patients (19%) had an ejection fraction less than or equal to 0.35. The mean number of grafts per patient was 1.7 (range, 1 to 3), and the internal mammary artery was used in 66 patients (86%). Only 18 patients (23%) received at least one graft to the circumflex artery. Hospital stay was 7.4 +/- 6.5 days.nnnRESULTSnEarly events included operative death in 4 patients (5.2%), nonfatal myocardial infarction in 3 (3.9%), sternal infection in 2 (2.6%), and stroke in 0 (0%). Follow-up (30 +/- 15 months) showed 11 deaths (5 cardiac, 6 noncardiac), 2 (2.8%) nonfatal myocardial infarctions, and return of angina in 9 patients (12.8%). One- and 4-year actuarial survival rates were 90% and 69%, respectively.nnnCONCLUSIONSnReoperative coronary artery bypass grafting without cardiopulmonary bypass has acceptable early and midterm outcome, and should be considered a viable alternative for properly selected patients.

Aprotinin improves hemostasis after cardiopulmonary bypass better than single-donor platelet concentrate

Platelet transfusion and aprotinin administration improve platelet function and clinical hemostasis after extracorporeal circulation. To compare two methods of improving postoperative hemostasis, we preoperatively randomized 40 patients undergoing various open heart procedures into two groups. Group A included 20 patients who, immediately after bypass, received single-donor plateletpheresis concentrates collected from ABO-compatible donors (Baxter Autopheresis-C System). They were compared with 20 patients who received high-dose aprotinin (6 x 10(6) KIU) before and during cardiopulmonary bypass (group B). Group A patients showed significantly higher platelet count after single-donor plateletpheresis concentrate transfusion (157 +/- 36 x 10(9)/L compared with 118 +/- 42 x 10(9)/L (p < 0.05). However, platelet aggregation on extracellular matrix was better in group B (3.4 +/- 0.7 versus 2.8 +/- 0.9; p < 0.05). Total 24-hour blood loss and exposure to homologous blood products were significantly less in group B (396 +/- 125 mL and 1.1 +/- 1.6 units compared with 617 +/- 233 mL and 5.4 +/- 3.4 units; p < 0.01). Despite higher platelet count in patients after single-donor plateletpheresis concentrates transfusion, hemostasis in patients receiving aprotinin is better due to improved platelet function.

Calculated Preoperative Mean Left Atrial Pressure as a Guide to Volume Load at the Termination of Aortocoronary Bypass Operation

The routine use of an arbitrary fixed left atrial (LA) pressure during volume load after aortocoronary bypass operation was compared with use of an individualized postoperative target LA pressure according to a calculated preoperative LA pressure in two groups of consecutive patients. The preoperative LA pressure of each patient was calculated from the preoperative left ventricular end-diastolic pressure (LVEDP) by the formula: mean LA pressure = 1.16 x LVEDP - 8.53. Left atrial pressure, mean arterial pressure, mean right atrial pressure, and cardiac output were measured simultaneously on arrival at the intensive care unit and 60 minutes later. Cardiac index (CI) and systemic vascular resistance (SVR) were calculated from the variables already mentioned. Results indicated a significantly higher CI and significantly lower SVR in patients in whom volume load was aimed at the calculated preoperative LA pressure. It was concluded that the optimal postoperative LA pressure is specific for each patient and depends on the preoperative LVEDP.

Is Transfusion of Fresh Plasma After Cardiac Operations Indicated

Patients undergoing cardiac operations constitute the majority of recipients of fresh frozen plasma. In most centers the reason for transfusing fresh frozen plasma is to replace clotting factors. However, the decrease of clotting factors during cardiopulmonary bypass is not sufficient in most patients to cause abnormal bleeding. One of the major causes of nonsurgical bleeding after cardiac operations is acquired platelet dysfunction, which can be corrected by transfusion of 1 unit of fresh whole blood. Because plasmatic factors in fresh whole blood may be responsible for this improvement, a study was designated to evaluate the effect of transfusing fresh plasma on platelet function after cardiac operations. Forty patients undergoing cardiopulmonary bypass were randomized to receive either fresh plasma or the fresh packed cell fraction. Administration of packed cells increased platelet number (118 +/- 8.5 to 154 +/- 7.6 x 10(9)/L, p less than 0.05), shortened bleeding time (7.57 +/- 0.4 to 4.0 +/- 0.3 minutes, p less than 0.05), and improved platelet aggregation in response to collagen and epinephrine (32% +/- 4.7% to 50% +/- 5.6% and 37% +/- 5.8% to 50% +/- 5.8%, respectively, p less than 0.05). Fresh plasma, however, neither increased platelet number nor improved bleeding time or platelet aggregation. Each group later received the remainder of the blood unit, with similar results. The results suggest that improvement of platelet function in patients receiving fresh whole blood after cardiac operations is not related to plasmatic factors. Therefore the massive use of fresh frozen plasma in patients after cardiopulmonary bypass should be reconsidered.

The Hemostatic Effect of Transfusing Fresh Whole Blood Versus Platelet Concentrates After Cardiac Operations

The major cause of nonsurgical bleeding after cardiopulmonary bypass is delayed recovery of platelet count and function. Recovery of platelet count and function was compared in 27 patients who were randomized preoperatively to receive after cardiopulmonary bypass either 1 unit of fresh whole blood (15 patients) or 10 units of platelet concentrates (12 patients). Platelet count, bleeding time, platelet aggregation (adenosine diphosphate, collagen, epinephrine, and ristocetin) and platelet thromboxane formation were abnormal after cardiopulmonary bypass in all the patients. The increase of platelet count after 1 unit of fresh whole blood (from 115 +/- 32 X 10(9)/L to 148.5 +/- 36 X 10(9)/L) was similar to that achieved by 4 units of platelets (from 140 +/- 61 X 10(9)/L to 171 +/- 60 X 10(9)/L). The increase was doubled after 10 platelet units (from 140 +/- 61 X 10(9)/L to 209 +/- 55 X 10(9)/L). Bleeding time returned to normal values after fresh whole blood or after 8 platelet units. However, platelet thromboxane formation was higher after 1 unit of fresh whole blood than after 10 platelet units (95 +/- 25 versus 46 +/- 35 ng/ml, p less than 0.05), as was platelet aggregation response to collagen and epinephrine. The 24-hour blood loss was smaller in the fresh whole blood group (560 +/- 420 ml versus 770 +/- 360 ml), although the difference was not statistically significant. The results suggest that the hemostatic effect of 1 unit fresh whole blood after cardiopulmonary bypass is at least equal, if not superior, to the effect of 10 units of platelets.

Inaccuracy of Radial Artery Pressure Measurement After Cardiac Operations

The phenomenon of a pressure gradient between central and radial arteries was evaluated in 48 patients immediately after coronary artery bypass operations. All were in stable hemodynamic condition, none receiving catecholamine support. In eight patients (Group A) mean femoral pressure was significantly higher than mean radial pressure (range 10 to 30 mm Hg). In the remaining 40 (Group B) radial and femoral pressures were equal. Mean cardiac index (thermodilution) was 3.3 +/- 0.68 versus 2.1 +/- 0.4 L/min/m2, systemic vascular resistance 1,181 +/- 218.4 versus 2,049 +/- 501 dynes/sec/cm-5, toe temperature 23.8 degrees +/- 1.2 degrees C versus 24.02 degrees +/- 0.9 degrees C, core temperature 33.9 degrees +/- 0.5 degrees C versus 34.1 degrees +/- 0.6 degrees C, mixed venous oxygen saturation 78% +/- 3% versus 62% +/- 5%, and peak radial dP/dt 1,485 +/- 366 versus 2,028 +/- 392 in Groups A and B, respectively. These data indicate, first, that the low radial pressures measured in Group A patients did not represent the true central aortic pressures; that is, they were false. Second, these low pressures had nothing to do with compromised cardiac function; rather, they were due to peripheral constriction and volume factors and also probably to proximal shunting. It is therefore recommended that while the chest is still open, if a discrepancy exists between a low radial artery pressure, a high palpable aortic pressure, and a satisfactory cardiac contraction, a femoral cannula for pressure measurement should be inserted. Treatment is by blood infusion until the femoral-radial gradient has been abolished.