Coronary Artery Bypass Grafting Nine Months after Pneumonectomy

Abstract

We performed coronary artery bypass grafting on a 58-year-old man who only 9 months earlier had undergone right pneumonectomy for bronchial carcinoma. Although his preoperative pulmonary function had been poor, coronary artery bypass surgery was successful, and the patient was discharged on the 9th postoperative day. Two years after surgery, he remained in New York Heart Association functional class I. We attribute this success to special management before, during, and after the operation. On the 32nd postoperative month, this patient died of multiple tumor metastases.

Impairment of pulmonary function is one of the most common and severe postoperative complications of coronary artery bypass grafting (CABG). The chance that this complication will occur, and its severity when it does occur, vary in accordance with the patient's preoperative respiratory reserves. Patients who have mildly impaired or normal pulmonary function can easily tolerate moderate pulmonary impairment after CABG. ^1,2 But this complication is not tolerated well by patients who have undergone pneumonectomy, because of their limited pulmonary function and reserves.

There are few published reports on the subject of CABG after pneumonectomy. ^3,4 In 1994, Medalion and associates ³ sent a questionnaire to 118 members of the Society of Thoracic Surgeons and received responses on 27 patients. According to this survey, patients had undergone open-heart procedures at a mean of 18 ± 13 years after pneumonectomy. Although our patient had undergone pneumonectomy only 9 months earlier, we performed CABG because of his unstable angina pectoris.

The purpose of this report is to introduce and discuss the topic of successful coronary artery bypass surgery after pneumonectomy.

Case Report

In July 1998, a 58-year-old man presented at our institution with unstable angina. Nine months before, he had undergone a right pneumonectomy because of bronchial carcinoma. He had diabetes mellitus and hypertension. Prior to his pneumonectomy, he had smoked cigarettes for 40 years. His medications included verapamil, isosorbide dinitrate, and an oral antidiabetic agent.

His temperature, pulse rate, and blood pressure were all within normal limits. Breath sounds over the left hemithorax were normal and right breath sounds were absent. Results of routine laboratory tests were within normal limits. The electrocardiogram revealed a normal sinus rhythm, with right-axis deviation. Postero-anterior radiography and computed tomographic imaging of the chest showed a shift of the trachea and mediastinum to the right and hyperinflation of the left lung (Fig. 1).

Fig. 1 Chest radiography (A) and computed tomographic imaging (B) show a shift of the trachea and mediastinum to the right side and hyperinflation of the left lung.

On the echocardiogram, the right ventricle was enlarged and the left ventricle was normal. A pulmonary function test showed both obstruction of the airway and restriction of the remaining lung. Arterial blood gases displayed an alkaline pH and hypoxemia (Table I). Coronary angiography revealed 85% stenosis of the proximal left anterior descending coronary artery, 90% stenosis of the 2nd obtuse marginal branch, and 80% stenosis of the proximal right coronary artery. During cardiac catheterization, the pulmonary artery, pulmonary capillary wedge, and central venous pressures were 35/18 mmHg, 12 mmHg, and 12 mmHg, respectively.

TABLE I. Pulmonary Function Test Results and Arterial Blood Gas Levels on Room Air

During the 7 days before CABG, our patient underwent preoperative pulmonary rehabilitation, including steroid administration, bronchodilation, and chest physiotherapy.

Anesthesia.

Before the patient was taken to the operating room, he was given 3 mg of midazolam intravenously. Prior to induction of anesthesia, an intra-arterial 22-gauge catheter was inserted into a radial artery for blood-pressure monitoring and blood sampling. Anesthesia was induced with thiopental, 4 to 7 mg/kg; fentanyl, 15 μg/kg; and vecuronium bromide, 0.1 mg/kg. Maintenance anesthesia included a 50/50 mixture of oxygen and air, together with 0.1% to 1% isoflurane (Siemens 710). Fentanyl, 15 μg/kg, and vecuronium, 0.1 mg/kg, were also administered during maintenance. After induction, a 7.5-F introducer was inserted into the right internal jugular vein to monitor pulmonary artery pressure.

Surgical Technique.

A median sternotomy was performed. Because the mediastinum had shifted to the right hemithorax, the aorta and right atrium were displaced to the posterior and to the right. We cannulated the aorta easily and inserted standard 2-stage cannulae through the right atrium into the inferior vena cava. A membrane oxygenator and roller pump were used during cardiopulmonary bypass. We used saphenous vein grafts to bypass the left anterior descending artery, the 1st obtuse marginal branch, and the posterior descending branch of the right coronary artery. The patient was weaned from cardiopulmonary bypass without difficulty, after which methylprednisolone (250 mg) was administered. The aortic cross-clamping and cardiopulmonary bypass times were 47 and 110 minutes, respectively.

The patient was extubated 6 hours postoperatively. Steroid and bronchodilation therapy, and chest physiotherapy, were continued during the postoperative period, which was uneventful. The patient was discharged from the hospital on the 9th postoperative day. Twenty-four months postoperatively, he continued in New York Heart Association functional class I. On the 32nd postoperative month, he died of multiple tumor metastases.

Discussion

Pulmonary dysfunction is one of the more severe postoperative complications of CABG. After CABG, important changes occur in pulmonary function. Usually, on the 1st postoperative day, the observed decrement in forced vital capacity (FVC) is around 70% of the preoperative value. Ten days after surgery, when most patients are able to be discharged from the hospital, the FVC has increased but still remains 30% lower than the preoperative value. ¹ Such a change can be tolerated easily by patients who have normal lung reserves. However, patients who have undergone a pneumonectomy tolerate the change with difficulty, because respiratory reserves usually decrease around 50% to 55% as a consequence of pneumonectomy alone. ⁵

Although it is known that adaptive mechanisms can increase pulmonary capacity gradually over the years after pneumonectomy, we were able to perform successful CABG only 9 months after our patient underwent pneumonectomy. This implies that special management may be a more important determinant than adaptation time.

Short-term pulmonary rehabilitation, which is feasible and effective in improving pulmonary function before surgery, reduces surgical morbidity and decreases substantially the cost of postoperative care. Chest physical therapy, steroid therapy, and bronchodilation should be started preoperatively. ⁶

Perioperative Considerations.

Due to the risk of pneumothorax, central venous lines should be inserted on the side of the pneumonectomy. Dissection and cannulation can be difficult in patients after pneumonectomy because of the cardiac displacement. Diaphragmatic paralysis as a result of cold injury to the phrenic nerve is reported to occur in up to 30% of patients after cardiopulmonary bypass (CPB), and to persist in one third of those patients at 1 year. ⁷ Therefore, topical hypothermia of the heart should not be used in patients who have only 1 lung. We did not use topical hypothermia, and our patient experienced no diaphragmatic paralysis.

The left and right internal mammary arteries (IMAs) should not be used, because the pedicled left IMA may not reach its targeted vessel and may be kinked by the hyperinflated left lung. Moreover, various studies ^1,8,9 have shown that increased pain associated with IMA harvesting may be related to decreased postoperative pulmonary function. Therefore, patients with ventilatory impairment should be excluded from IMA grafting. ^1,8 We did not use the IMA.

After the operation, patients should be ventilated with low pressure to avoid pulmonary barotrauma, and they should be extubated as early as possible to avoid the complications of prolonged intubation. ¹⁰ Early mobilization is important to avoid the development of deep venous thrombosis and atelectasis. The patient should be treated with routine chest physiotherapy after surgery to reduce the possibility of atelectasis. The development of pulmonary congestion and bronchospasm can be avoided through the routine use of diuretics and systemic steroids. Postoperative pain, which can decrease pulmonary function, ⁹ should be treated with nonsteroidal anti-inflammatory drugs. Beta-adrenergic blockade may exacerbate the bronchospasm and should be avoided.

We have presented herein our experience with a patient who underwent CABG only 9 months after pneumonectomy. Twenty-four months postoperatively, he continued in New York Heart Association functional class I. Although a single case does not constitute proof, we believe that open-heart surgery, with special management, can be performed successfully mere months after pneumonectomy.