A Novel Approach to Coronary Revascularization in Patients with Severely Diseased Aorta

Abstract

Atheromatous disease of the aorta significantly increases morbidity and mortality during coronary revascularization. The surgical approach must be modified for patients in whom this condition is identified. In this report, we describe a technique that uses bilateral internal thoracic arteries as composite grafts with reverse saphenous veins. The operation is performed without cardiopulmonary bypass. We report the cases of 2 patients who underwent this procedure. Neither patient experienced signs or symptoms of atheromatous embolization, and there was no perioperative morbidity or mortality. Off-pump myocardial revascularization using bilateral internal thoracic arteries is an attractive surgical approach for patients who have atheromatous aortas or other conditions in which it is advantageous to avoid aortic manipulation, cannulation, cross-clamping, and cardiopulmonary bypass.

Atheromatous embolization is of major concern during myocardial revascularization. A prospective study of routine coronary artery bypass grafting (CABG) found that the incidence of stroke or other serious neurologic outcome was approximately 3.1%, and this incidence increases dramatically with age. ¹ In addition, atheroemboli may affect the peripheral extremities and organs such as the kidneys, spleen, liver, and adrenal glands. ^2,3 These complications may lead to significant debilitation or death. ^1,2 In an autopsy series, Blauth and colleagues ³ reported that atheroembolic events occurred in 37.4% of patients who had severe disease of the ascending aorta. Cannulation or manipulation of an atheromatous aorta places the patient at a significant risk of atheroembolic event, and patients who are found intraoperatively to have a diseased aorta require modification in surgical technique. Several authors ^4–7 have previously described the aortic no-touch technique. However, in these patients cardiopulmonary bypass (CPB) and hypothermic fibrillatory arrest were performed, along with femoral or axillary cannulation. In this report, we present 2 patients who were completely revascularized without CPB. In both patients, we constructed composite grafts using both internal thoracic arteries (ITA) in combination with reversed saphenous veins (RSV).

Surgical Procedure

Anesthetic Technique

Both patients underwent cardiac revascularization without CPB, as described by Jansen and co-workers. ⁸ Anesthesia was induced with sufentanil and pancuronium. Intraoperatively, hemodynamic status was monitored with an arterial line, a Swan-Ganz catheter, and transesophageal echocardiography. Heart rate was maintained at approximately 60 beats/minute using esmolol. Mean arterial pressure was maintained at approximately 65 to 75 mmHg using phenylephrine and 100 to 250 cc boluses of lactated Ringer's solution as needed. Both patients were extubated within the first 12 hours after surgery.

Patient 1

A 78-year-old man with a history of hypertension, hypercholesterolemia, and angina presented to his primary physician complaining of dyspnea. He underwent cardiac catheterization, which demonstrated triple-vessel disease with preservation of ventricular function. He was referred to our institution for surgery.

The heart was exposed via a median sternotomy. Upon exploration, we found that the aorta was extensively calcified. To avoid manipulation of the aorta, we harvested both the right and the left ITA in situ. We used a mechanical suction stabilizer (Medtronic Octopus®2; Medtronic, Inc.; Minneapolis, Minn) to locally immobilize the target vessels for each anastomosis and placed an occluding suture to stop blood flow at the arteriotomy anastomosis site until an intraluminal shunt was placed.

We positioned the heart by using posterior pericardial retraction sutures, and we opened the right pleura in order to rotate the heart into the right hemithorax and thereby avoid compression of the right ventricle. The area surrounding each vessel was stabilized by using the suction stabilizer. As shown in Figure 1A, we constructed RSV grafts to the obtuse marginal (OM) and the 1st diagonal arteries. We grafted the in situ left ITA to the mid-portion of the left anterior descending artery (LAD). We anastomosed the end of the diagonal graft to the side of the OM graft. The right ITA was used to provide inflow to the 2 RSV grafts.

Fig. 1 Schematic representations of myocardial revascularization in Patients 1 (A) and 2 (B).

LITA = left internal thoracic artery; RITA = right internal thoracic artery; RSVG = reversed saphenous vein graft

Postoperatively, the patient was hemodynamically stable and showed no signs of atheroembolization. The patient developed ileus, which resolved on the 4th postoperative day. He was discharged on the 6th postoperative day.

Patient 2

A 67-year-old man with a history of hypertension, cerebrovascular accident, myocardial infarction, and peptic ulcer presented to his primary physician complaining of nocturnal dyspnea. The patient was transferred to our institution for testing. Transthoracic echocardiography disclosed mild mitral regurgitation, mild dilatation of the left atrium and the aortic root, and hypertrophy of the left ventricle with severe inferior wall hypokinesis. Cardiac catheterization showed triple-vessel disease with total occlusion of the mid-portion of the LAD and collateral vessels arising from the posterior descending artery (PDA) and circumflex artery. The ejection fraction was estimated to be 30%.

We performed a median sternotomy to expose the heart and harvested both the right and the left ITA in situ. The heart was positioned with posterior pericardial retraction sutures. Using a mechanical suction stabilizer (Medtronic Octopus®2), we anastomosed a RSV graft to the diagonal artery (Fig. 1B). We then anastomosed the left ITA to the mid-portion of the LAD and grafted a separate RSV to the PDA. Local perfusion was maintained during each anastamosis by using intraluminal shunts. We created an oblique end-to-end anastomosis between the vein grafts. Finally, we anastomosed the right ITA, which was used as the inflow vessel, to the vein, near the site of the veno-venous anastomosis.

Postoperatively, the patient was hemodynamically stable. He experienced no complications, and he was discharged on the 5th postoperative day.

Discussion

Atheromatous aorta may be detected preoperatively or intraoperatively by ultrasonography. Diagnosis of this condition should prompt the surgeon to modify or eliminate aortic manipulation. ⁹ We believe that, in cases of severe aortic disease, aortic manipulation should be avoided by use of a no-touch technique. Mills and Everson ¹⁰ constructed a composite graft, using the in situ left ITA, a RSV, and a free inferior epigastric artery as grafts to the LAD, 2nd diagonal, and OM arteries. In addition, they grafted a right gastroepiploic artery and a RSV to the PDA and right posteriolateral arteries. This operation was performed with use of CPB and vented fibrillatory arrest.

We have presented the cases of 2 patients who underwent total myocardial revascularization off-pump, using both ITAs in combination with RSV grafts. This method obviates the risks of aortic or peripheral cannulation and CPB. We prefer to leave the left ITA as the sole source of inflow to the LAD without using it to perfuse other conduits. In most cases, patency of the graft from the left ITA to the LAD is critical to long-term survival. Because both short- and long-term survival of the patient can be substantially affected if a technical failure occurs secondary to multiple side-to-side or end-to-side anastomoses, we have chosen to use the right ITA as the source of inflow to composite RSV grafts that supply myocardium not perfused by the LAD.

Hart and co-workers, ¹¹ in a report of 374 patients who underwent coronary revascularization without CPB, reported neurologic deficit in only 0.26% of the patients. They suggested that off-pump myocardial revascularization may offer an advantage in reducing morbidity and mortality. Specifically, they noted a reduction in renal, respiratory, and cerebrovascular complications. We believe that this novel combination of off-pump, no-touch technique is a viable approach for patients who have an atheromatous aorta and who may therefore be predisposed to embolic events when the aorta is cannulated. This procedure may be applied to other patients in whom aortic cannulation and partial occlusion are hazardous, such as those with a thickened or dilated aortic wall.

The use of bilateral ITA grafts for myocardial revascularization may predispose some patients to complications. In their review of 246 patients who received bilateral ITA grafts, Kouchoukos and colleagues ¹² reported a 6.9% rate of sternal wound infection; the rate was 1.3% in patients who were revascularized with a unilateral IMA. Other risk factors for sternal wound infections included diabetes, obesity, and prolonged mechanical ventilation. Grossi and colleagues ¹³ reported that the risk of sternal wound infection increased 13.9 fold in diabetic patients who received bilateral ITA grafts. Given this significantly increased risk of sternal wound infection in diabetics, we would advocate, when possible, creation of an alternative arterial inflow, such as the right gastroepiploic artery, to avoid harvesting the right ITA. We have also used saphenous or free radial grafts, supplied directly by the subclavian artery, when the ITA and the gastroepiploic arteries were not available.

Although the long-term patency of coronary grafts performed without CPB remains to be studied, we believe that the benefits of not manipulating an atheromatous aorta and of avoiding CPB outweigh the risk of early graft occlusion. In recent studies, the safety and efficacy of off-pump myocardial revascularization is becoming evident. The off-pump, no-touch technique is an attractive option for patients who are at high risk of cerebrovascular or other systemic embolization.