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Ann Thorac Surg 1999;68:1482-1485
© 1999 The Society of Thoracic Surgeons
a Thoracic and Cardiovascular Surgery, ETMC Cardiovascular Institute, Mother Frances Heart Institute, Tyler, Texas, USA
Address reprint requests to Dr Turner, PO Box 150, Tyler, TX 75710
e-mail: wftjr{at}tyler.net
Presented at Evolving Techniques and Technologies in Minimally Invasive Cardiac Surgery, San Antonio, TX, Jan 22–23, 1999.
Abstract
Background. In an effort to avoid the adverse effects of cardiopulmonary bypass, "off-pump" myocardial revascularization has been rediscovered and refined. This study reviews the first 100 off-pump coronary artery bypass procedures performed in Tyler, TX, and compares the results with those reported in the Seventh Annual Report of the Society of Thoracic Surgeons (STS) Cardiac Surgery Database.
Methods. Coronary artery bypass was performed on 100 patients without cardiopulmonary bypass over a 24-month period. Postoperative morbidity, mortality, and length of stay were recorded.
Results. Operative mortality was 3%. The incidences of postoperative complications for the off-pump group versus the STS database were as follows: reoperation for bleeding, 1% vs 2.2%; transfused patients, 15% vs 35%; atrial fibrillation, 5% vs 18.2%; infection, 2% vs 1.3%; neurologic, 0% vs 5.1%; renal failure, 0% vs 3.12%; ventilation more than 1 day, 0% vs. 5.69%. The postoperative length of stay for the off-pump group versus the STS group was 4.4 vs 6.6 days.
Conclusions. Early results suggest that off-pump coronary artery bypass grafting is a safe and effective means of coronary revascularization with excellent short-term results and minimal morbidity.
Although current techniques of coronary artery bypass grafting (CABG) utilizing cardiopulmonary bypass (CPB) seem both safe and effective, the adverse cerebral effects and risk of blood transfusion should not be underestimated.
Stroke after coronary surgical procedures is usually embolic and related to cardiopulmonary bypass, cannulation, or surgical manipulation of the aorta. Subtle neurological and cognitive deficits can be detected through neuropsychological testing, and have been reported in up to 50% of patients after CPB [1, 2].
In addition, blood contact with artificial surfaces of the CPB circuit produce a well-documented systemic inflammatory responsive that affects multiple organ systems [3, 4]. Specific adverse effects of this inflammatory response have been documented in the heart, lungs, central nervous system, kidneys, and gastrointestinal tract, and are felt to be a major cause of postoperative morbidity. In an effort to avoid the adverse effects of CPB, "off-pump" myocardial revascularization has been rediscovered and redefined.
CABG was first performed without the use of CPB in the late 1960s [5, 6], but this technique was largely abandoned after the widespread adoption of CPB and cardioplegic arrest.
Recently, Calafiore [7], Benetti [8], and Subramanian [9] and associates independently reported large series that suggest off-pump cardiopulmonary bypass (OPCPB) grafting is a safe and effective means of coronary revascularization in patients with single- and multi-vessel coronary artery disease (CAD) with excellent short-term results and minimal morbidity.
This study reviews the clinical experience of the first 100 OPCAB bypass grafting procedures performed by a single surgeon in Tyler, TX. Clinical outcomes are compared with those reported in the Seventh Annual Report of the Society of Thoracic Surgeons (STS) Cardiac Surgery Database [10].
Material and methods
CAB was performed on 100 patients without cardiopulmonary bypass by a single surgeon from July 1996 through June 1998. After review of coronary angiograms, patients were selected based on the location and size of target arteries and level of left ventricular function.
The patient group underwent primarily elective single- and multi-vessel CABG through a left anterior mini-thoracotomy and partial or full median sternotomy approaches.
Early in the series, only patients with single-vessel disease involving the anterior descending coronary artery or right coronary arteries were considered for off-pump myocardial revascularization. Indications for surgery in this group were patients who were felt to be unsuitable for catheter-based intervention by the referring cardiologist or who had presented with restenosis after angioplasty or stent placement. In addition, patients with multiple medical comorbidities such as uncontrolled diabetes mellitus, renal failure, malignancies, and cerebrovascular disease, who were felt to be at increased risk for CPB, were also referred for OPCAB grafting. Encouraged by our early success with single-vessel disease, we began to consider all patients with multivessel CAD as potential candidates for off-pump myocardial revascularization.
Contraindications to surgery for both single-vessel and multivessel OPCAB grafting included patients with very large hearts that do not tolerate manipulation, decompensated heart failure, intramyocardial coronary arteries, inaccessible calcified coronary arteries, and small coronary arteries (less than 1.5 mm in diameter).
Standard cardiac anesthetic techniques were used, including a Swan-Ganz catheter in all patients. Changes in ST segments were monitored using an on-line three-channel electrocardiogram (ECG; precordial leads II, V5, and AVL). Temporary single-lung ventilation could be performed with a double-lumen endotracheal tube. The operating room was warmed and the unoperated body of the patient was covered by a warm air flow blanket to sustain body temperature greater than 36.5°C. For single-vessel left anterior descending coronary artery grafting, the procedure was accomplished through a left anterior mini-thoracotomy (approximately 8 cm) made in the fourth intercostal space. The left internal mammary artery was harvested through this incision with a commercially available retractor (Cardiothoracic Systems, Cupertino, CA) Heparin (3 mg/kg) was administered before division of the internal mammary artery. The artery was treated with an intraluminal administration of a solution consisting of verapamil 5.0 mg, nitroglycerin 2.5 mg, heparin 500 U, 8.4% sodium bicarbonate 0.2 mL, and Ringer’s solution at 300 mL [11].
After dissection of the target artery, arterial occlusion was accomplished by a single, proximal, encircling silicone vascular loop (Quest Medical, Inc, Allen, TX), leaving the distal artery undisturbed. A commercial mechanical stabilizer was utilized during the anastomosis.
The distal anastomosis was sewn using 7-0 polypropylene sutures in continuous manner under direct vision. A humidified sterile carbon dioxide "blower" was used to clear the field of blood. Ischemic preconditioning, intraluminal coronary shunts, and pharmacological stabilization with adenosine and beta-blockers were rarely used.
A partial lower sternotomy was preferentially used for single right coronary artery grafting. Using this approach, a 10-cm incision was made over the lower one-third of the sternum with division completed to a point below the second intercostal space. Sternal vision was extended to the right side, thus creating a "trap door."
In cases involving multivessel OPCAB grafting, the procedure was performed through a median sternotomy. This incision offers excellent exposure for safe internal mammary artery harvest and precise coronary artery anastomosis, and allows rapid conversion to CPB if necessary. In cases where multiple grafts are indicated, a predetermined sequence of grafting was utilized to decrease the magnitude of systemic effects resulting from local ischemia during occlusion of the coronary artery.
In general, the left anterior descending coronary artery is bypassed first to secure revascularization to the anterior wall and intraventricular septum. After this anastomosis, the collateralized (occluded or highly stenotic) artery is bypassed before the collateralizing artery. Exposure to the anterior descending and circumflex coronary arteries was improved by deeply placed traction sutures in the left pericardium that caused the heart to rotate forward and immediately. Hypotension that accompanied cardiac manipulation was counteracted by placing the patient in the steep Trendelenburg position combined with a volume infusion of 1 to 1.5 L of normal saline.
Stabilization and anastomotic techniques were similar to those used for single-vessel OPCAB grafting. Heparin was fully reversed with protamine sulfate.
Transthoracic Doppler flow evaluation of the artery was performed postoperatively in the intensive care unit and at 3, 6, and 12 months in the first 50 patients undergoing single-vessel off-pump myocardial revascularization. Postoperative morbidity, mortality, and length of stay were recorded.
Results
Group comparisons were made on the basis of preoperative demographics and major risk factors, and postoperative morbidity, mortality, and length of stay. For the purpose of this study, two-group comparisons were made. All off-pump patients (thoracotomy and sternotomy approaches) were considered together and compared with patients reported in the Seventh Annual Report of the STS Cardiac Surgery Database.
Due to the small number of cases reported in this early series, statistical analysis to determine significant differences between the two groups could not be performed.
Tables 1 and 2 show the preoperative demographics and major risk factors between the two groups. The two groups were examined on the basis of age, gender, operative status, (elective/emergent; redo), ejection fraction, and seven major risk factors. Table 3 reviews the postoperative results. The large number of single-vessel bypass operations reflects our early philosophy of limiting OPCAB grafting to patients with single-vessel CAD.
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Every patient in this study received at least one internal thoracic coronary artery graft.
Operative mortality was defined as death that occurred during the same hospitalization or less than 30 days after operation. [12] The operative mortality was 3% (3 patients). The causes of death were cardiogenic shock (a patient with severe left ventricular systolic dysfunction who underwent redo-redo single-vessel minimally invasive direct coronary artery bypass [MIDCAB]), septic shock (a patient who underwent an emergent triple-vessel OPCAB during an evolving anterior myocardial infarction who subsequently developed gangrenous necrosis of the small bowel), and malignant ventricular tachycardia refractory to resuscitative measures (a patient with preoperative severe ventricular dysfunction with multiple episodes of recurrent ventricular tachycardia who underwent a triple-vessel OPCAB).
The average postoperative length of stay is shown in Table 3. Patients undergoing multivessel OPCAB grafting were hospitalized approximately 1 day longer than those who underwent single-vessel OPCAB grafting.
The instances of postoperative complication are shown in Table 4. Reoperations for bleeding, infections, and dysrhythmias were rare. There were no postoperative neurologic, renal, or pulmonary complications.
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Angiography was mandatory in a patient with a suspicion of an anastomotic malfunction as suggested by echo Doppler assessment, or clinical suspicion of recurrent angina.
Table 5 shows the postoperative assessment of graft patency with Doppler echocardiography and/or angiography performed on the first 50 patients.
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A well-functioning left internal mammary artery, detected by an echo Doppler or angiography, was obtained in 46 patients (92%).
Pioneered by Benetti [8] and Buffalo [14] almost 20 years ago, CABG without CPB continues to be a procedure in evolution. Following the success of minimally invasive bypass procedures using a left internal mammary artery bypass to the left anterior descending artery via a left anterior small thoracotomy without CPB [7], rapid developments in surgical techniques enabled OPCAB grafting to be performed through a sternotomy for patients with multivessel CAD.
In addition to the extensive experience of Benetti and Buffalo, which span more than a decade, recent reports by others have documented that myocardial revascularization without CPB can be performed safely and applied to a large population of patients with single- and multi-vessel CAD [8, 9].
Although the small numbers of this early experience precluded meaningful statistical analysis, the results presented here suggest that OPCAB grafting is a safe and effective means of coronary revascularization in patients with single- and multivessel CAD with excellent short-term results and minimal morbidity.
As older, sicker patients are referred for CABG, an increased proportion of patients may have a relative contraindication for CPB. In addition, as changes in the clinical practice of operation are increasingly driven by economic considerations, the emphasis in cardiac operation is on techniques that are performed with lower overall morbidity and mortality, and result in shorter length of stay and lower hospital cost.
In summary, this report reviews an initial experience with 100 patients undergoing CABG without CPB. With new emerging technologies designed to optimize anastomotic precision combined with standardization of surgical technique and team experience, the proportion of patients undergoing OPCAB grafting versus conventional CABG with CPB is likely to increase and the clinical results are likely to improve.
References
This article has been cited by other articles:
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  R A Archbold and N P Curzen Off-pump coronary artery bypass graft surgery: the incidence of postoperative atrial fibrillation Heart, October 1, 2003; 89(10): 1134 - 1137. [Abstract] [Full Text] [PDF]
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 S. J. George, S. Al-Ruzzeh, and M. Amrani Mitral annulus distortion during beating heart surgery: a potential cause for hemodynamic disturbance--a three-dimensional echocardiography reconstruction study Ann. Thorac. Surg., May 1, 2002; 73(5): 1424 - 1430. [Abstract] [Full Text] [PDF]
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A. C. Anyanwu, S. Al-Ruzzeh, S. J. George, R. Patel, M. H. Yacoub, and M. Amrani Conversion to off-pump coronary bypass without increased morbidity or change in practice Ann. Thorac. Surg., March 1, 2002; 73(3): 798 - 802. [Abstract] [Full Text] [PDF]
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 B. T. Lorenz and K. M. Coyte Coronary Artery Bypass Graft Surgery Without Cardiopulmonary Bypass: A Review and Nursing Implications Crit. Care Nurse, February 1, 2002; 22(1): 51 - 60. [Full Text] [PDF]
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 D. L Zarro, D. A Palanzo, and R. M Montesano A comparison of several variables of off-pump coronary artery bypass procedures versus myocardial revascularization utilizing cardiopulmonary bypass Perfusion, January 1, 2002; 17(1): 9 - 14. [Abstract] [PDF]
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 D. Varghese, M. H. Yacoub, R. Trimlett, and M. Amrani Outcome of non-elective coronary artery bypass grafting without cardio-pulmonary bypass Eur. J. Cardiothorac. Surg., March 1, 2001; 19(3): 245 - 248. [Abstract] [Full Text] [PDF]
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