Is pre-transplant vascular disease a risk factor for mortality and morbidity after heart transplantation?☆

BACKGROUND

Severe vascular disease is a relative contraindication to heart transplantation (HTx). We addressed the effect of vascular disease on HTx outcomes.

METHODS

This is a nonconcurrent cohort study of 402 patients who received HTx at our institution between 1985 and 2004. Pre-transplant vascular evaluation included carotid, lower extremity, and renal artery duplex studies, and CT angiogram when indicated. Patients with severe and nontreatable vascular disease were excluded. Patients were divided into Group 1: those with pre-transplant vasculopathy, and Group 2: those without pre-transplant vasculopathy. Group 1 had 24 patients with 25 vascular lesions: 1 aortic dissection, 2 abdominal aortic aneurysm (AAA)'s, 5 carotid artery stenoses, 1 renal artery stenosis, and 16 peripheral vascular lesions. Interventions were performed to 15 lesions prior to HTx and to 2 lesions after HTx.

RESULTS

Median follow-up was 5.5 years. Group 1 had higher incidence of ischemic cardiomyopathy (p<0.001), hypertension (p=0.028), chronic obstructive pulmonary disease (COPD) (p=0.004), and smoking history (p<0.001). There were no differences in sex, hyperlipidemia, diabetes, stroke, or renal dysfunction. Multivariate analysis revealed odds of post-transplant death in Group 1 was 1.4 (95% CI: 0.48-4.1, p=0.54) times greater than that in Group 2. Cox proportional hazards model for survival showed a 50% increase in the hazard of death in patients with pre-transplant vasculopathy, but without statistical significance. Group 1 had higher incidence of post-transplant stroke (p=0.001) but no difference in allograft coronary atherosclerosis.

CONCLUSIONS

Pre-transplant vascular disease seems to have negative effect on outcomes after HTx. Larger scale study is needed for further evaluation.

Effects of a statewide physician-led quality-improvement program on the quality of cardiac care

BACKGROUND

Several states have implemented mandatory public reporting of outcomes of cardiac revascularization procedures. Washington is the first to develop a nonmandatory, physician-led reporting program with public accountability and universal hospital participation. The purpose of this study was to determine whether quality improvement interventions resulted in the correction of data deficiencies and performance outliers for cardiac revascularization procedures.

METHODS

From 1999 through 2003, there were 18 hospitals with coronary bypass surgery and interventional cardiology programs and 12 with only the latter. All patients > or =18 years undergoing 24372 isolated coronary bypass surgeries and 59,656 percutaneous coronary interventions were included. After 1999 to 2001 data were analyzed in early 2002, the Clinical Outcomes Assessment Program implemented a 6-step quality-improvement intervention to measure and remeasure data quality, process compliance, and performance.

RESULTS

In 2003, 4 of the 18 surgery programs had 1 statistical outlier with respect to 4 performance measures, whereas 2 of 30 coronary intervention programs were mortality outliers. For bypass surgery, all programs maintained full compliance with program standards by adhering to timely and reliable submission of data, developing plans to address performance outliers, and demonstrating that outlier status did not persist from baseline to remeasurement. For coronary interventions, 1 program was a persistent outlier for mortality in 2002 and 2003.

CONCLUSIONS

The Clinical Outcomes Assessment Program has successfully monitored cardiac care patterns in Washington State over a 5-year period. Most hospitals that perform coronary revascularization procedures meet acceptable performance standards.

Expectant management is safe for cholelithiasis after heart transplant

BACKGROUND

The optimal management of cholelithiasis after heart transplant remains unclear. We use expectant management based on symptoms, without screening studies or prophylactic treatment. We hypothesized that expectant management for cholelithiasis after heart transplant does not result in significant mortality or morbidity from gallstone-associated disease.

METHODS

Between November 1985 and August 2004, 409 heart transplants were performed in 402 recipients at the University of Washington. This is a non-concurrent cohort study of these recipients.

RESULTS

Among recipients, 24 underwent cholecystectomy before heart transplant. After transplant, in the remaining 378 patients, 34 were found to have gallstones during the observation period. There was no mortality from gallstone-associated disease. Thirty patients developed morbidity from gallstones, including 25 cases of biliary colic, 3 of acute cholecystitis and 2 of pancreatitis, and there was 1 abnormal liver function test. Acute cholecystitis and pancreatitis were treated with conservative management followed by cholecystectomy. Cholecystectomy was performed in 32 patients after transplant. Indications included symptomatic cholelithiasis in 31, and prophylactic cholecystectomy prior to kidney transplant in 1. The laparoscopic approach was performed in 25 of these 32 patients. There was no mortality from cholecystectomy, but there were 4 complications: surgical site infections (n = 2); wound dehiscence (n = 1); and bile duct injury (n = 1). Median hospital stay was 1 day.

CONCLUSIONS

Our expectant management for cholelithiasis after heart transplant resulted in no mortality or significant morbidity related to delay in treatment. Symptomatic cholelithiasis was successfully treated with cholecystectomy, mostly with the laparoscopic approach. We believe expectant management is safe for patients after heart transplant.

Strategies to reduce hemostatic activation during cardiopulmonary bypass

INTRODUCTION

We evaluated whether a modified protocol for cardiopulmonary bypass (CPB) could reduced the systemic hemostatic activation associated with this procedure.

MATERIALS AND METHODS

The in vivo rates of thrombin, fibrin, plasmin and D-dimer generation were determined in each subject during CPB using measured levels of hemostatic factors combined with a computer model of the cardiovascular and hemostatic systems. A standard CPB group using uncoated circuits, standard heparin levels and direct shed blood reinfusion (n=9) was compared to a modified CPB group using heparin-coated circuits, shed blood collection, washing and reinfusion post-operatively, lower heparin levels and epsilon-amino-caproic acid (n=10).

RESULTS AND CONCLUSIONS

Standard CPB increased average thrombin generation 9-fold, decreased fibrin generation 2-fold, increased plasmin generation 11-fold and increased fibrin degradation and D-dimer generation 19-fold. During CPB in the modified group thrombin generation was not increased beyond surgical levels, lower heparin concentrations allowed each thrombin to make more fibrin prior to inhibition, while fibrin degradation was suppressed by epsilon-amino-caproic acid. At baseline for every 100 fibrins formed only 1-2 were degraded to D-dimer. During standard CPB for every 100 fibrins generated on average 34 fibrins were degraded with some subjects showing a net fibrin loss. In contrast, in the modified CPB group for every 100 fibrins formed only 4 fibrins were degraded (p<0.0001 vs. standard group). Kinetic modeling of hemostasis in individual patients showed that a modified CPB protocol could reduce excessive thrombin generation during CPB and suppress fibrin degradation moving hemostatic regulation back towards normal.

Open-chest management after heart transplantation

Postcardiotomy open-chest management has been widely used in cardiac surgery. Although this strategy can be applied to heart transplantation, the use of immunosuppressants in transplant recipients raises particular concerns about sternal wound infection and impaired healing. We performed a retrospective review of 403 patients who had undergone 410 heart transplantations at our institution from 1985 through 2004. Among them, 9 patients (2.2%) had open-chest management postoperatively. There were 8 men and 1 woman, with a mean age of 58 +/- 7 years. The graft ischemic time ranged from 130 to 374 minutes (mean, 218 +/- 99 min), and the cardiopulmonary bypass time ranged from 98 to 360 minutes (mean, 210 +/- 69 min). In all cases, the reason for open-chest management was hemodynamic lability that precluded chest closure after transplantation. One patient also experienced postoperative bleeding. All patients underwent delayed sternal closure between postoperative days 1 and 11 (median, 4 days). Delayed sternal closure did not cause any significant hemodynamic changes. One patient died of stroke on postoperative day 22. No patient had sternal wound infection or impaired wound healing during the follow-up period. We conclude that, when required, open-chest management is an effective and safe measure for hemodynamically unstable heart transplant patients.

A Phase III, Double-blind, Placebo-controlled, Multicenter Study on the Efficacy of Recombinant Human Antithrombin in Heparin-resistant Patients Scheduled to Undergo Cardiac Surgery Necessitating Cardiopulmonary Bypass

Background

The study evaluated the efficacy of recombinant human antithrombin (rhAT) for restoring heparin responsiveness in heparin resistant patients undergoing cardiac surgery.

Methods

This was a multicenter, randomized, double-blind, placebo-controlled study in heparin-resistant patients undergoing cardiac surgery with cardiopulmonary bypass. Heparin resistance was diagnosed when the activated clotting time was less than 480 s after 400 U/kg heparin. Fifty-four heparin-resistant patients were randomized. One cohort received 75 U/kg rhAT, and the other received normal saline. If the activated clotting time remained less than 480 s, this was considered treatment failure, and 2 units fresh frozen plasma was transfused. Patients were monitored for adverse events.

Results

Only 19% of patients in the rhAT group received fresh frozen plasma, compared with 81% of patients in the placebo group (P &lt; 0.001). During their hospitalization, 48% of patients in the rhAT group received fresh frozen plasma, compared with 85% of patients in the placebo group (P = 0.009). Patients in the placebo group required higher heparin doses (P &lt; 0.005) for anticoagulation. There was no increase in serious adverse events associated with rhAT. There was increased blood loss 12 h postoperatively (P = 0.05) with a trend toward increased 24-h bleeding in the rhAT group (P = 0.06). There was no difference between the groups in blood and platelet transfusions.

Conclusion

Treatment with 75 U/kg rhAT is effective in restoring heparin responsiveness and promoting therapeutic anticoagulation in the majority of heparin-resistant patients. Treating heparin-resistant patients with rhAT may decrease the requirement for heparin and fresh frozen plasma.

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.

Reducing Hemostatic Activation During Cardiopulmonary Bypass: A Combined Approach

Interventions such as heparin-coated circuits, epsilon-aminocaproic acid, and reduced shed blood reinfusion have shown mixed results when applied individually for limiting hemostatic activation during cardiopulmonary bypass (CPB). We compared coagulation and fibrinolytic activation during conventional CPB (control) (CTRL) using noncoated circuits, no antifibrinolytics, and open cardiotomy with a combined strategy (HAC) that used heparin-coated circuits, epsilon-aminocaproic acid, and closed cardiotomy. Blood samples were drawn before, during, and after CPB for primary coronary bypass grafting surgery from 9 CTRL patients and 10 HAC patients. Thrombin-antithrombin complex and fibrinopeptide A levels (markers of thrombin and fibrin generation) were reduced in the HAC versus CTRL group after 30 min of CPB (P < 0.05). Average tissue plasminogen activator (tPA) levels were significantly lower in the HAC group by 30 min on CPB (P < 0.05), resulting in preservation of plasminogen activator inhibitor (PAI)-1 during CPB (P < 0.05). D-Dimer, a measure of intravascular fibrin formation and removal, was reduced in the HAC group during and after CPB (P < 0.005). Overall, the combined strategy was associated with a reduction in CPB-induced increases in markers of thrombin generation, fibrin formation, tPA release, and fibrin degradation and better preservation of PAI-1.

IMPLICATIONS

A combined approach during cardiopulmonary bypass (CPB) that uses heparin-coated circuits, epsilon-aminocaproic acid, and limited reinfusion of shed pericardial blood is associated with reduced activation of the coagulation and fibrinolytic systems that typically occurs during conventional CPB.

The effect of left internal mammary artery utilization on short-term outcomes after coronary revascularization

BACKGROUND

The purpose of this study was to determine whether use of the left internal mammary artery (LIMA) during coronary revascularization influences short-term morbidity in all patients undergoing revascularization, as well as in patients over the age of 75 years, female patients, and patients with diabetes. The study also explored variability in the utilization of LIMA grafts across an entire state.

METHODS

Using the Clinical Outcomes Assessment Program (COAP) of the state of Washington, procedural outcomes were compared for patients receiving and patients not receiving LIMA grafts as part of revascularization procedures from January 1, 1999 to December 31, 2000. Mortality and major complications were examined, both as unadjusted rates and after adjusting for baseline patient risk factors.

RESULTS

A total of 16 centers performed 8,797 nonemergent coronary artery revascularizations, including 81.7% with LIMA grafts. The use of a LIMA graft was associated with a significantly lower mortality (3.7% No LIMA vs 1.6% LIMA), as well as decreases in ventricular arrhythmias, need for postoperative dialysis, need for transfusions, ventilator dependence, and length of hospital stay. These trends were true for the population as a whole as well as for all subgroups analyzed, and they persisted after correcting for differences in comorbid conditions. In addition, there was wide variability in the use of LIMA grafts from center to center in the state.

CONCLUSIONS

The use of LIMA grafts for coronary revascularization is associated with decreased mortality and morbidity. Despite these advantages, there is great variability in its application across the state of Washington.

Biphasic shocks compared with monophasic damped sine wave shocks for direct ventricular defibrillation during open heart surgery

BACKGROUND

Biphasic waveform shocks are more effective than monophasic shocks for transchest ventricular defibrillation, atrial cardioversion, and defibrillation with implantable defibrillators but have not been studied for open chest, intraoperative defibrillation. This prospective, blinded, randomized clinical study compares biphasic and monophasic shock effectiveness and establishes intraoperative energy dose-response curves.

METHODS

Patients undergoing cardiothoracic surgery with bypass cardioplegia were randomly assigned to the monophasic or biphasic shock group. Ventricular fibrillation occurring after aortic clamp removal was treated with escalating energies of 2, 5, 7, 10, and 20 J until defibrillation occurred. If ventricular fibrillation persisted, a 20-J crossover shock of the other waveform was used.

RESULTS

Cumulative defibrillation success at 5 J, the primary end point of the study, was higher in the biphasic group than in the monophasic group (25 of 50 vs. 9 of 41 defibrillated; P = 0.011). In addition, the biphasic group required lower threshold energy (6.8 vs. 11.0 J; P = 0.003), less cumulative energy (12.6 vs. 23.4 J; P = 0.002), and fewer shocks (2.5 vs. 3.5; P = 0.002). Crossover-shock effectiveness did not differ between groups. Dose-response curves show biphasic shocks to have higher cumulative success rates at all energies tested.

CONCLUSIONS

Biphasic shocks are substantially more effective than monophasic shocks for direct defibrillation. The dose-response curve guides selection of first-shock energy for traditional step-up protocols. Starting at 5 J optimizes for lowest threshold and cumulative energy, whereas 10 or 20 J optimizes for more rapid defibrillation and fewer shocks.

Use of off-pump and on-pump CABG strategies in current clinical practice: the Clinical Outcomes Assessment Program of the state of Washington

BACKGROUND

The purpose of this study is to assess clinical outcomes and regional differences in the use of on-pump and off-pump CABG in current clinical practice.

METHODS

Between January 1, 1999, and December 31, 2000, there were 10,429 CABG procedures performed in 16 Washington state hospitals, all of which participate in Clinical Outcomes Assessment Program database. This analysis excluded patients with a history of prior CABG as well as those who underwent emergent surgery. After applying these exclusion criteria, 8402 patients (7169 on-pump and 1233 off-pump CABG procedures) were evaluated and presented as both unadjusted and risk-adjusted outcomes.

OUTCOMES

Off-pump CABG constituted 14.7% of all surgical revascularization procedures. These varied enormously among individual centers from an incidence of 0% to 68.9%. The use of off-pump CABG was not associated with a decreased risk of risk-adjusted hospital mortality or stroke, but was associated with a reduction in hospital stay > 7 days (OR 0.62, CI 0.51-0.76), ventilator > 24 hours (OR 0.52, CI 0.34-0.81), dialysis (OR 0.34, CI 0.14-0.86), and RBC transfusion (OR 0.5, CI 0.40-0.61).

CONCLUSIONS

Despite its highly variable use, off-pump CABG seems to be judiciously used in current clinical practice in the State of Washington and is associated with a decrease in morbidity in appropriately selected patients.

A review of leukofiltration in cardiac surgery: the time course of reperfusion injury may facilitate study design of anti-inflammatory effects

The systemic inflammatory response syndrome (SIRS) is a well-recognized phenomenon attending cardiopulmonary bypass (CPB) surgery. SIRS leads to costly complications and several strategies intended to ameliorate the symptoms have been studied, including leukocyte reduction using filtration. Although the body of work suggests that leukoreduction attenuates SIRS, discrepancies remain within the literature. The recent literature is reviewed, highlighting the areas where concordance is lacking. Investigations into many promising device-related technologies are often deterred by the high costs of clinical trials. Adding to costs is the fact that clinical end points generally require large sample sizes. An understanding, however, of the pathogenesis of reperfusion injury can guide the investigator to choose physiologic response measures that correlate well with clinical outcome, but feature low inherent variability, allowing for clinical trials with smaller sample sizes. With this goal in mind, a model for the pathogenesis of reperfusion injury is described. Using a model of reperfusion injury as underpinnings for the design of prospective pilot studies, we show that salvaged blood reinfused following CPB elicits time-dependent effects on pulmonary function as predicted by the model. Data are illustrative of principles that could expand the scope of clinical investigations designed to validate the use of physiologic response measures as correlates of clinical outcome. Such investigations would target surrogate markers of clinical outcome, measured at clinically relevant times. Once validated, these surrogate markers would, thereafter, become economical screening tools for clinical studies of device-related or pharmacological anti- inflammatory interventions.

Limitation of thrombin generation, platelet activation, and inflammation by elimination of cardiotomy suction in patients undergoing coronary artery bypass grafting treated with heparin-bonded circuits

OBJECTIVE

Reports evaluating the efficacy of heparin-bonded circuits to blunt inflammation, platelet dysfunction, and thrombin generation in response to cardiopulmonary bypass have varied. We hypothesized that this variability may in part be related to the use of cardiotomy suction, which has been demonstrated to reintroduce procoagulant and proinflammatory factors into the systemic circulation during cardiopulmonary bypass. A prospective, randomized study was undertaken to evaluate the specific effects of cardiotomy suction.

METHODS

Thirty-six patients undergoing first-time, nonemergency coronary artery bypass grafting with cardiopulmonary bypass were randomly assigned to one of three treatment groups: group I, non-heparin-bonded circuits with the use of cardiotomy suction (n = 12); group II, Duraflo II (BCR-3500; Jostra Bentley Corp, Irvine, Calif) heparin-bonded circuits with cardiotomy suction (n = 12); and group III, Duraflo II heparin-bonded circuits without cardiotomy suction (n = 12). Thrombin generation, neutrophil activation (polymorphonuclear elastase), platelet activation (beta-thromboglobulin), and neuronal injury (neuron-specific enolase) were analyzed by enzyme-linked immunosorbent assays after cardiopulmonary bypass and compared with prebypass levels. Results are presented as mean +/- SEM.

RESULTS

Prebypass levels of all markers were similar among treatment groups. However, postbypass levels were significantly and consistently highest in group I relative to groups II and III. Thrombin generation levels were 5.0 +/- 0.9 nmol/L in group I, 3.0 +/- 0.6 nmol/L in group II, and 1.5 +/- 0.1 nmol/L in group III (P <.05 vs group II and P <.001 vs group I). Polymorphonuclear elastase levels were 307 +/- 64 microg/L in group I, 128 +/- 24 microg/L in group II (P <.05 vs group I), and 75 +/- 14 microg/L in group III (P <.001 vs group I). beta-Thromboglobulin levels were 2692 +/- 401 IU/mL in group I, 912 +/- 99 IU/mL in group II (P =.001 vs group I), and 646 +/- 133 IU/mL in group III (P =.001 vs group I). Neuron-specific enolase levels were 9.8 +/- 0.9 ng/mL in group I, 10.5 +/- 1.6 ng/mL in group II, and 4.2 +/- 0.5 ng/mL in group III (P =.001 vs groups I and II).

CONCLUSIONS

Use of cardiotomy suction resulted in significant increases in thrombin, neutrophil, and platelet activation, as well as the release of neuron-specific enolase, after cardiopulmonary bypass. Limiting increases in these markers would be best accomplished by eliminating cardiotomy suction and routinely using heparin-bonded circuits whenever possible.

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.

What constitutes optimal surgical revascularization? Answers from the Bypass Angioplasty Revascularization Investigation (BARI)

OBJECTIVES

The study was done to derive the optimum definition of complete revascularization in coronary artery bypass surgery.

BACKGROUND

"Complete revascularization" has been considered the goal of coronary artery bypass operations, but various definitions of completeness exist.

METHODS

We evaluated the Bypass Angioplasty Revascularization Investigation (BARI) surgical results in the seven years after operation. Different definitions of completeness of revascularization were retrospectively applied to the 1,507 patients in the combined randomized/registry group to derive the definition of complete operative revascularization with the best discrimination in long-term results between those with and without complete revascularization as defined. Four definitions were evaluated: 1) traditional complete revascularization with one graft to each major diseased artery system; 2) functional complete revascularization with one graft to all diseased major or primary segmental vessels; 3) number of distal anastomoses greater than, equal to or less than the number of diseased coronary segments; and 4) number of distal anastomoses to the major coronary systems equal to 1 or greater than 1.

RESULTS

No independent survival advantage existed for traditional or functional complete revascularization as compared with incomplete revascularization. No survival advantage existed for any of the three arms of definition 3. For definition 4, seven-year death/myocardial infarction was highest (32.9%) when more than one anastomosis was constructed to any non-left anterior descending coronary artery (LAD) system (relative risk 1.37, p = 0.03). No increased risk was associated with constructing more than one anastomosis into the LAD system.

CONCLUSIONS

The construction of more than one graft to any system other than the LAD appears to confer no long-term advantage, and may actually be deleterious.

Delayed surgical management of a traumatic aortic arch injury

We report successful management of a blunt traumatic injury to the aortic arch with intentionally delayed surgical repair. The aorta was repaired after the stabilization of other, potentially fatal, traumatic injuries.

Effects of increased pressure inside or outside ventricles on total and regional myocardial blood flow

Increasing pressures to 30 mmHg in right (RV) and left (LV) ventricles and surrounding heart (SH) in isolated, arrested, maximally vasodilated, blood-perfused dog hearts shifted pressure-flow (PF) curves rightward and increased zero flow pressure (P(zf)) by an amount equal to the RV applied pressure, SH applied pressure, or two-thirds of the LV applied pressure. There were comparable increases in coronary venous pressures. Increasing LV or SH pressures decreased coronary blood flows, especially in the subendocardium. Decreases in driving pressure decreased flows in all layers, but even with driving pressure of 5 mmHg, a few subepicardial pieces had flow. We conclude with the following: 1) raising pressures inside or outside the heart shifts PF curves and raises P(zf) by increasing coronary venous pressure; 2) the effects are most prominent in the subendocardial muscle layer; and 3) as driving pressures are decreased, there is a range of P(zf) in the heart with the final P(zf) recorded due to the last little piece of muscle to be perfused.

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.

Nitroglycerin is preferable to diltiazem for prevention of coronary bypass conduit spasm

BACKGROUND

Diltiazem is widely used to prevent radial artery spasm after coronary bypass grafting (CABG). However, recent in vitro and in vivo studies have shown that nitroglycerin is a superior conduit vasodilator compared to diltiazem. A clinical comparison of these agents in patients undergoing CABG has not been previously performed.

METHODS

One hundred sixty-one consecutive patients undergoing isolated CABG with the radial artery were prospectively randomized to 24-hour intravenous infusion of nitroglycerin or diltiazem followed by 6-month treatment with a daily dose of isosorbide mononitrate (n = 84) or diltiazem CD (n = 77). Analyses were performed on "intention-to-treat" basis.

RESULTS

Crossovers because of low cardiac output, complete heart block, or sinus bradycardia occurred in 5 patients in the diltiazem group and none in the nitroglycerin group (p = 0.05). Operative mortality (nitroglycerin, 1.2% versus diltiazem, 1.3%), major morbidity (14% versus 16%), perioperative myocardial infarction (1.2% versus 0%), peak serum creatinine phosphokinase MB fraction levels (27 versus 21 U), intensive care unit stay (34+/-19 versus 38+/-30 hours) and total hospital length of stay (4.7+/-1.4 versus 4.7+/-1.3 days) were similar (p = not significant for all). Cardiac pacing was required more often in the diltiazem group (28% versus 13%, p = 0.01). Follow-up longer than 2 months was available in 145 patients (90%). Follow-up mortality (nitroglycerin, 1.2%; diltiazem, 1.3%), myocardial infarction (6%, versus 5%), and reintervention (8% versus 6%) rates and average angina class (1.3+/-0.7 versus 1.1+/-0.4) were similar (p = not significant for all). Thallium stress test obtained in 117 patients showed abnormal perfusion in the radial artery territory in only 4 patients (3%), 2 in each group (p = not significant). Treatment with diltiazem was more costly ($16,340 versus $1,096).

CONCLUSIONS

Nitroglycerin is preferable to diltiazem for prevention of conduit spasm. Nitroglycerin is safe, effective, better tolerated, and less costly than diltiazem, and therefore, should be the agent of choice.