Complete Off-Pump Coronary Revascularization in Patients with Dialysis-Dependent Renal Disease

Abstract

Patients who have dialysis-dependent renal disease frequently present with coronary artery disease but are considered at high risk for coronary artery bypass grafting.

From 1 September 2000 through 31 August 2003, we performed complete off-pump coronary revascularization in 6 patients who had end-stage dialysis-dependent renal failure, and we prospectively studied the perioperative and early postoperative results. The effect of off-pump coronary artery bypass grafting on mortality, morbidity, postoperative complications, and transfusion requirements in this group of patients was investigated. No perioperative deaths or ischemic cardiac events were observed after off-pump coronary artery bypass grafting. In all patients, anginal symptoms were relieved during the postoperative period. The mean duration of follow-up was 17.2 ± 12.4 months.

Patients with dialysis-dependent chronic renal failure who present with coronary artery disease should be thoroughly evaluated preoperatively for risk factors and coexistent severe diseases. We believe that in patients with end-stage dialysis-dependent chronic renal failure, off-pump coronary revascularization is a good alternative.

Cardiac diseases are reportedly responsible for about 44% of the deaths among patients who are in chronic renal failure. ¹ Due to frequent hypotensive episodes or angina, dialysis sessions may need to be performed in a limited fashion or even stopped prematurely.

About two thirds of all cases of chronic renal failure are caused by primary hypertension, diabetes mellitus, or both. Indeed renal failure and diabetes are closely associated with cardiovascular disorders. This coexistence makes the treatment of patients with renal failure highly complex. Just as in diabetes, the atherosclerotic process follows an aggressive course in renal failure. The presence of hypertension, hyperlipidemia, and abnormal carbohydrate metabolism all contribute to this accelerated atherosclerosis. ² The optimal management of patients who have all the diseases mentioned here—the pre- and postoperative measures, and the choice of operative strategy—has very important implications. Potential problems associated with cardiopulmonary bypass (CPB), such as fluid-electrolyte balance, hemoglobin concentration, and hemostasis, all make optimal perioperative management indispensable.

It is widely known that end-stage renal failure is a major risk factor for cardiac operations in which CPB is used. ³ The general condition of the patient, the coexistence of the above-mentioned diseases, the probability of infection, and the susceptibility of these patients to coagulopathy together make off-pump coronary revascularization a suitable alternative strategy. In this prospective study, we report the results, in 6 dialysis-dependent, end-stage renal failure patients, of complete revascularization with use of an off-pump coronary artery bypass surgery technique.

Patients and Methods

At Kosuyolu Heart and Research Hospital, from 1 September 2000 through 31 August 2003, we performed off-pump coronary artery bypass surgery on 6 dialysis-dependent end-stage chronic renal failure patients (2 men and 4 women). The mean age of the patients was 54.5 ± 9.3 years (range, 41–56 years) at the time of the operation. All patients were on hemodialysis, but none on peritoneal dialysis. Renal failure had been caused by hypertensive nephropathy in 3 patients (one of whom had renal artery stenosis), by diabetes mellitus in 2 patients (one of whom was insulin-dependent), and by systemic lupus erythematosus in the remaining patient. The mean duration of preoperative dialysis was 2.4 ± 1.6 years. The preoperative characteristics of the patients are presented in Table I. The mean ejection fraction of the 6 patients was 0.43 ± 0.05 (range, 0.35−0.50). The preoperative creatinine value was 6.51 ± 2.77 mg/dL. Because our patient with renal artery stenosis had end-stage renal disease and controlled blood pressure, we did not attempt correction of the renal stenosis before coronary revascularization. The patient with lupus erythematosus was not in an acute flare-up stage of the lupus at the time of revascularization.

TABLE I. Patients' Preoperative Characteristics

In 5 patients, the indication for surgery was Canadian Cardiovascular Society (CCS) grade III–IV angina that was unresponsive to medical treatment; in the other patient, the indication was symptomatic congestive heart failure secondary to ischemic heart disease. Preoperatively, 2 patients were in New York Heart Association (NYHA) functional classes I–II, and the remaining 4 were in NYHA classes III–IV (Table I).

Surgery and Perioperative Care

All patients underwent a hemodialysis procedure 24 hours before the operation so that they would have optimal fluid-electrolyte and urea-creatinine values at surgery. All coronary artery bypass grafting (CABG) operations were performed through median sternotomies. In total, 15 distal anastomoses were performed. Table II shows the preoperative angiographic lesions of the patients and the arteries that underwent bypass (or in 1 case, stenting). A saphenous vein graft was used for revascularization of the left anterior descending coronary artery (LAD) in 1 patient who had peripheral arterial disease; the left internal mammary artery (LIMA) was used in the remaining 5 patients. In 5 patients, the Genzyme immobilizer (Genzyme Surgical Products; Fall River, Mass) was used. We used the Starfish 2 Heart Positioner (Medtronic; Minneapolis, Minn) in the other patient. In all 6 patients, anticoagulation was maintained with 50 mg of heparin, which enabled us to keep the activated clotting time (ACT) between 200 and 250 seconds. All the anastomoses were secured with 7/0 or 8/0 Prolene continuous sutures. At the time of the operation, optimal fluid balance was reached, and caution was taken not to administer excessive fluids. Potassium-rich solutions were not used and hemoglobin levels were kept above 10 g/dL to the extent possible. To optimize the preload, fresh plasma was used when fluid replacement was needed, and packed red blood cells were used to increase the hematocrit levels when needed. Extubation was done in accordance with the standard regimen that we follow for every bypass surgery patient. In our series, we did not observe any cardiac complication, and minimal inotropic support was needed in only 1 patient, whose preoperative ejection fraction was below 0.35.

TABLE II. Angiographic Results and Surgical Intervention

If potassium levels and urea-creatinine values were stable and if volume status was normal, hemodialysis was not started until the 2nd postoperative day.

Results

We did not observe any perioperative mortality. None of the patients needed early dialysis. In the event of high potassium levels, we easily reduced them to normal through use of balanced glucose-insulin solutions. Kayexelate was not used in any of the patients. The frequency of the dialysis was determined on an individual basis by closely monitoring laboratory results and the status of the patients. The thoracic drainage tubes were taken out on the 2nd postoperative day. No ischemic electrocardiographic changes were observed perioperatively. The patient whose preoperative ejection fraction had been 0.35 received small amounts of inotropic solutions. Strict control of bleeding yielded an average intraoperative blood loss of 286.7 ± 64.4 mL (range, 190–380 mL). No cell-saver was needed for autotransfusion due to intraoperative blood loss. Intraoperatively, none of our patients required whole blood or freshly frozen plasma, but a mean of 0.50 ± 0.4 IU packed red blood cells was transfused. Postoperatively, the mean drainage amount was 600 ± 459.34 mL (range, 200–1,500 mL); 0.75 ± 0.61 IU of whole blood, 1 IU of freshly frozen plasma, and 1.75 IU of packed red blood cells were administered to each patient. After the dialysis procedure, none of the patients had any drainage problems.

Hemofiltration was not needed for any patient in the intensive care unit. The frequency of postoperative hemodialysis was unchanged from that of preoperative hemodialysis.

The mean duration of mechanical ventilation was 9.8 ± 5.5 hours (range, 6–20 hours), and the mean duration of the intensive care unit stay was about 2.83 ± 1.47 days (range, 1–5 days). The mean duration of the hospital stay was 20.5 ± 10.2 days (range, 6–37 days). The anginal symptoms of all patients improved during the early postoperative period. The mean duration of follow-up was 17.2 ± 12.4 months (range, 2–39 months), and none of our patients presented with ischemic complaints or cardiac problems during follow-up. Four of the 6 patients had CCS grade I angina during follow-up. Postoperatively, 4 of the 6 patients were in NYHA functional class I, and the remaining 2 were in NYHA class II.

Discussion

The underlying cause of death in 40% to 50% of patients on hemodialysis is coronary artery disease. It is not well known whether the progression of the coronary artery disease has a more accelerated course in hemodialysis patients, but many studies report that cardiac disorders have a more serious outcome in the presence of coexisting diseases, including established renal failure. ⁴ Calcification of the heart valves, coronary arteries, and the conduction system, and the probability of septic events such as endocarditis, are typical complications of long-term hemodialysis. ⁵ In spite of the fact that reports on the outcomes of cardiac procedures and their effects on the long-term prognosis of patients with dialysis-dependent renal disease are scarce, recent findings indicate acceptable mid- and long-term results. ^6,7

Complications after coronary artery bypass surgery are seen more often in end-stage renal failure patients than in other patients. Accelerated atherosclerosis and diffuse cholesterol embolization produce cerebrovascular and visceral vascular complications. The high percentage of preoperative myocardial infarctions in these patients and the presence of triple-vessel disease and calcific arterial lesions all point to an accelerated progression of atherosclerotic disease. Postoperatively, the more frequent need of inotropic medications also indicates a higher risk of major cardiac events in these patients. In various studies, advanced age has been the most important predictive factor in survival of these patients, but cerebrovascular disease, an ejection fraction of less than 0.35, and the need for hemodialysis are other strong predictive factors. ⁸ Due to the presence of calcified coronary artery lesions, surgeons usually have had to perform incomplete revascularizations in dialysis-dependent patients. ⁹

Many of the complications associated with CABG in dialysis patients may be related to the use of CPB. ¹⁰ Disorders such as platelet dysfunction and susceptibility to infection increase the operative morbidity and mortality. The susceptibility to infections is related to decreased leukocyte chemotaxis and to leukopenia. During CPB, there is difficulty in maintaining the fluid-electrolyte balance in dialysis-dependent patients; and in dialysis patients who have undergone CPB, there is greater risk of bleeding complications. ¹⁰ Off-pump coronary artery bypass surgery minimizes these problems. Admittedly, our number of patients was small; nonetheless, we had only 1 bleeding problem in 1 patient and solved it without reoperation, which tends to support our way of thinking. The bleeding diathesis associated with end-stage renal disease was resolved in this patient with appropriate postoperative transfusions of whole blood and freshly frozen plasma. The decreased number of intraoperative transfusions lessened transfusion-related complications.

It is widely known that cerebrovascular accidents are seen more frequently in patients who undergo CPB. Obviating the need to cross-clamp the aorta in diffusely atherosclerotic renal failure patients has the further advantage of diminishing the risk of thromboembolic events. None of our patients experienced a cerebrovascular event.

The maintenance of a good fluid-electrolyte balance, the avoidance of potassium-rich solutions in volume replacement, the decreased need for blood transfusions, the avoidance of potassium-rich banked bloods, and the early use of balanced glucose-insulin solutions all helped to delay the need for hemodialysis until the 2nd day of the postoperative period. In this way, it may be possible to delay and thereby lessen the detrimental effects of hemodialysis on hemodynamic parameters and on the bleeding diathesis in the very early postoperative period.

Coronary artery disease is widely prevalent in chronic, end-stage renal failure patients, and the risk of cardiovascular interventions is substantial. Hemodialysis patients who undergo conventional CABG are at risk of CPB-related complications such as bleeding, volume overload, and cerebrovascular accidents. Because we did not observe any deaths or operation-related morbidity in the 6 patients upon whom we operated, and because their extubation times, cardiac complications, and times of intensive care stay were comparable with those of patients not in renal failure, we suggest that off-pump coronary artery bypass surgery is an excellent alternative for hemodialysis-dependent renal failure patients.