Combined Coronary Artery and Abdominal Aortic Surgery without Cardiopulmonary Bypass

Abstract

To determine the effects of beating heart surgery on patients undergoing simultaneous coronary artery bypass grafting and abdominal aortic surgery, we performed such surgery on 20 patients (mean age, 64.55 ± 7.96 SD years). Abdominal aortic disease was defined as an abdominal aortic aneurysm larger than 5 cm in diameter or as end-stage aortic occlusive disease. Hemodynamic measurements, inotropic requirements, and incidence of perioperative myocardial infarction and arrhythmias were recorded, as were subsystem clinical outcomes, length of intensive care unit and hospital stays, blood loss, and transfusion requirements.

There was no incidence of death, perioperative myocardial infarction, stroke, or acute renal failure. The mean number of grafts per patient was 1.95 ± 0.69. Only 4 minor postoperative complications were observed: three patients (15%) had evidence of supraventricular tachyarrhythmias, and 1 patient (5%) had chest infection that required a longer-than-average intubation period. Six patients (30%) required minimal-to-moderate inotropic support. The mean blood loss was 673 ± 246.8 mL and transfusion requirements were low. The mean intensive care unit and hospital lengths of stay were 2.12 ± 0.33 days and 7.08 ± 1.44 days, respectively. Clinical follow-up (mean, 10 months) showed all patients to be in New York Heart Association functional class I or II with no late cardiac or abdominal events.

We conclude that simultaneous coronary artery bypass grafting and abdominal aortic surgery on the beating heart is safe and effective, and has a low perioperative clinical morbidity rate. To our knowledge, ours is the 1st report on this procedure. Larger studies with longer follow-up are needed.

Coronary artery disease frequently coexists with marked abdominal aortic disease. ¹ In comparison with a 2-staged surgical approach to treat these conditions, combined procedures have been reported to have a lower incidence of perioperative myocardial infarction and postoperative rupture of abdominal aortic aneurysm (AAA). ^2–5

Current methods of coronary artery bypass grafting (CABG) are generally safe and effective. Morbidity rates are still high, however, mostly because of the whole-body response to the nonphysiologic nature of cardiopulmonary bypass (CPB) ⁶ and cardioplegic arrest. ⁷ Recently, there has been a revival of interest in performing CABG on the beating heart ^7–10 to improve myocardial function ⁷ and eliminate the inflammatory response due to CPB. ⁸ We hypothesized that using such a strategy for combined CABG and abdominal aortic surgery could further decrease the early perioperative morbidity rates, while maintaining the advantages of a simultaneous approach.

We report the effects of beating heart surgery in patients undergoing combined coronary artery and abdominal aortic surgery, in terms of perioperative morbidity.

Patients and Methods

Twenty patients (18 men and 2 women) were enrolled in a study to determine the effects of simultaneous CABG and abdominal aortic surgery performed on the beating heart. The mean age of these patients was 64.5 ± 7.9 SD years; the age range was 52–76 years. Exclusion criteria comprised recent myocardial infarction (<1 month), coronary artery disease involving the distal branches of the circumflex coronary artery, and reoperation. All patients underwent elective CABG in combination with abdominal aortic surgery, either for an AAA larger than 5 cm in diameter or for end-stage aortic occlusive disease. Diagnosis was made through routine abdominal angiography during coronary evaluation. All patients underwent surgery without CPB.

Administration of Anesthesia and Heparin. Intravenous anesthesia was administered with a propofol infusion at 3 mg · kg⁻¹ · hr⁻¹ combined with fentanyl at 10 to 15 mcg · kg⁻¹ · min⁻¹. Neuromuscular blockade was achieved with use of 0.1 to 0.15 mg/kg pancuronium or vecuronium bromide. The lungs were ventilated to normocapnia with air and oxygen (45%–50%), without positive end-expiratory pressure. A mean arterial pressure of 60 mmHg or more was maintained with vasoconstrictors or volume as dictated by the patient's individual hemodynamic condition. A 1-mg bolus of propranolol was given and was increased by increments as necessary to maintain a heart rate of less than 70 beats/min.

Before the 1st coronary anastomosis was begun, heparin (100 IU/kg) was administered to achieve an activated clotting time (ACT) of 250 to 350 seconds. This ACT level was also maintained during the abdominal procedure. When the abdominal surgery was completed, protamine was given to reverse the effect of the heparin and to restore a preoperative ACT level.

Surgical Technique. A routine median sternotomy was performed. Heart exposure and stabilization to perform the anastomosis was achieved by use of the CTS retractor and stabilizer (Guidant: formerly CardioThoracic Systems, Inc.; Cupertino, Calif). ¹¹ The target vessel was then exposed and snared above the anastomotic site using a GORE-TEX suture with a soft plastic snugger to prevent coronary injury. The coronary artery was then opened and the anastomosis performed. Visibility was improved by use of a surgical blower-humidifier. The proximal anastomoses were then performed with partial clamping. After a standard sternal approximation, a midline xipho-pubic incision was made, the abdominal viscera were mobilized, and the AAA was controlled. The abdominal aorta was then clamped and the operation was performed with our standard technique. After aortic declamping, protamine was administered to restore a preoperative ACT value, and the abdomen was closed.

Hemodynamic Measurements and Inotropic Management. Hemodynamic measurements were obtained by inserting a Swan-Ganz catheter as a part of the anesthetic protocol. The evaluation was performed preoperatively and at 1, 4, 12, 24, 36, and 48 hours postoperatively. Inotropic administration was predefined as follows: minimal, dopamine infusion of 3 mcg · kg⁻¹ · min⁻¹; moderate, dopamine infusion of 3 to 5 mcg · kg⁻¹ · min⁻¹; and maximal, adrenaline or enoximone infusion.

Perioperative Clinical Outcome. Perioperative myocardial infarction, stroke, acute renal failure, and gastrointestinal events were defined and recorded as major complications. The incidence of minor complications related to the clinical function of each subsystem was also systematically recorded.

Results

Preoperative and operative variables are shown in Tables I and II, respectively. The mean number of grafts placed per patient was 1.95 ± 0.69 grafts; there were 38 distal coronary anastomoses in all. The abdominal aortic surgeries included the insertion of 16 straight tube grafts and 4 bifurcated grafts. The mean aortic cross-clamping time for the abdominal surgeries was 54.6 ± 9.8 minutes.

Table I. Preoperative Clinical Data in 20 Study Patients

Table II. Surgical Data in 20 Patients Undergoing CABG and AAS without CPB

Perioperative myocardial infarction was defined as the occurrence of new Q waves longer than 0.04 ms or a reduction in R waves of more than 25% in at least 2 leads. However, no perioperative myocardial infarction occurred; nor was there any perioperative death, stroke, or acute renal failure. Hemodynamic values are shown in Table III. Six patients (30%) required minimal-to-moderate temporary inotropic support. Perioperative clinical outcomes are reported in Table IV. There were only 4 minor complications (20%): 3 patients (15%) had evidence of supraventricular tachyarrhythmias, and 1 patient (5%) had a chest infection, confirmed by positive sputum culture, which required antibiotic treatment and slightly prolonged intubation.

Table III. Hemodynamic Values in 20 Patients Undergoing CABG and AAS without CPB

Table IV. Perioperative Clinical Outcomes in 20 Patients

The mean blood loss was 673 ± 246.8 mL at 24 hours. This low blood loss meant that the transfusion requirements, in terms of whole blood or packed cells (mean, 0.20 ± 0.52 units) and fresh frozen plasma (mean, 0.10 ± 0.45 units), were also low. No platelets were required, and no reoperation for bleeding was necessary. The mean length of stay in the intensive care unit (ICU) was 2.15 ± 0.37 days, and the mean length of stay in the hospital was 7.10 ± 1.48 days.

Complete clinical follow-up at a mean of 10 months showed all patients to be in New York Heart Association functional class I or II. No late cardiac or abdominal events occurred.

Discussion

The combination of coronary artery disease and abdominal aortic disease is a common medical phenomenon in elderly patients. ¹ Up to 80% of patients with abdominal aortic disease show angiographic evidence of atherosclerosis in at least 1 coronary vessel. ¹² Several authors ^2–4 have reported that undetected coronary artery disease is a major determinant of both early and late mortality due to perioperative myocardial infarction in patients undergoing peripheral vascular surgery. Moreover, it has been reported that a delay of more than 2 weeks in performing AAA repair after a CABG procedure may lead to increased patient mortality as a result of aneurysmal rupture. ² During the 1990s, this evidence prompted the initiation of several studies that used a combined surgical approach, which proved safer and more effective than 2-staged operations. ^1–4,13

Recently, beating heart surgery has been attracting renewed attention. ^7–10 This is due, at least in part, to the introduction of mechanical stabilization of the myocardial wall, which allows the surgeon to suture anastomoses more precisely than was previously possible.

Few authors have reported early perioperative outcome after combined surgery for coronary artery and abdominal aortic disease on the beating heart. Of these, Lachat and coworkers ¹⁴ performed minimally invasive coronary artery bypass combined with vascular and general abdominal procedures on 8 of 40 high-risk patients, and the incidence of perioperative morbidity was low.

To our knowledge, ours is the 1st report of combined surgery for coronary artery and abdominal aortic disease on the beating heart. Advantages of performing CABG on the beating heart through a median sternotomy include multiple coronary grafting capabilities; a minimal inflammatory response; better myocardial protection; and reduced neurological deficits caused by under-perfusion, emboli from the CPB pump, and aortic cross-clamping. ^7,15 Our purpose was to extend these advantages to high-risk patients with coronary artery disease who also required abdominal aortic surgery.

In 1998, Brasil and colleagues ⁹ detected no inflammatory response after performing CABG on the beating heart. That same year, King and co-authors ¹ speculated that the inflammatory response caused by CPB might have a direct effect on the aneurysm wall, leading to decreased tensile strength and further dilation. Because collagen is thought to be the main constituent of the aneurysm wall, the increased collagenase activity occurring after major surgical procedures might be responsible for early aneurysmal expansion and rupture, as suggested by Busuttil's group ¹⁶ in 1980.

Our study clearly shows a low perioperative morbidity rate (20%) in comparison with rates found in other studies (38% ⁵ and 52.2% ¹³) after combined procedures performed with CPB. The absence of perioperative myocardial infarction and the low incidence of arrhythmias and inotropic support requirements may account for the lack of myocardial injury with beating heart surgery. This benefit, along with the elimination of the need for atrial cannulation, could explain the lower incidence of supraventricular tachyarrhythmias compared with rates as high as 30% to 40% in elective CABG procedures performed with CPB. ¹⁷

The cause of pulmonary dysfunction after open heart surgery is thought to be multifactorial, including the effects of prolonged anesthesia, CPB, and surgical trauma. Cardiopulmonary bypass is known to activate inflammatory processes, which increase pulmonary capillary permeability and damage the lung parenchyma. ⁶ In our opinion, this is particularly true when abdominal surgery is involved, because of the transient impairment of diaphragmatic function. Gade and associates ⁵ performed a retrospective review of 26 patients who underwent combined CABG and AAA repair. A comparative analysis of nonsurvivors (n = 3) and survivors (n = 23) revealed that prolonged CPB and postoperative respiratory failure were associated with higher mortality. Our study shows a very low incidence of respiratory complications, which suggests that the avoidance of CPB may be important in terms of preventing chest infection—especially when there are concomitant risk factors, such as internal mammary artery harvesting, abdominal surgery, and prolonged intubation time. The patients in our study had a low blood loss and low transfusion requirement, as well as a short length of stay in the ICU and hospital. These results, of course, have an important impact on total cost. In addition, other positive effects, such as the avoidance of bleeding-related complications (tamponade, renal failure, prolonged mechanical ventilation, atrial arrhythmias, and death), can be inferred. ¹⁸ The reduction of transfusion-related complications, such as the transmission of AIDS and hepatitis B and C, ¹⁹ as well as sternal infection, ²⁰ should also be taken into account.

Limitations of this study include the relatively small number of patients enrolled and the relatively short follow-up period. Continued follow-up and further clinical studies should be carried out to ensure that postoperative morbidity and mortality rates remain low and that there are no long-term complications, particularly any that would require reoperation or percutaneous transluminal coronary angioplasty.

In conclusion, this study comprising 20 patients clearly shows that a simultaneous surgical approach for CABG and abdominal aortic surgery on the beating heart is a safe and effective procedure with a low morbidity rate in the perioperative period. Studies involving both larger numbers of patients and longer follow-up are needed to strengthen these findings.