Asian Cardiovasc Thorac Ann 2008;16:159-161
© 2008 Asia Publishing EXchange Ltd
Left Heart Pump-Assisted Beating Heart Coronary Surgery in High-Risk Patients
Paolo Pepino, MD,
Piermario Oliviero, MD,
Francesco Petteruti, MD,
Luigi di Tommaso, MD1,
Mario Monaco, MD1,
Paolo Stassano, MD1
Department of Cardiothoracic Surgery, Clinica Pineta Grande, Castel Volturno
1 Department of Cardiac Surgery, University "Federico II", Naples, Italy
For reprint information contact: Paolo Pepino, MD, Tel: 39 082 385 4246, Fax: 39 082 385 4439, Email: paolo.pepino{at}fastwebnet.it, Via A. Manzoni 78, 80123 Naples, Italy.
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ABSTRACT
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A simple technique of left ventricular assistance, offering the advantages of both cardiopulmonary bypass and off-pump revascularization, was adopted for high-risk patients. It was used in 56 patients with critical left main stenosis and occluded right coronary artery, severely reduced ejection fraction and/or unstable angina. All patients underwent complete and successful myocardial revascularization (3.4 grafts per patient). Weaning from the pump was uncomplicated, and none required conversion to full cardiopulmonary bypass.
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INTRODUCTION
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Improvements in cardiopulmonary bypass (CPB) technology have been substantial and have helped to improve the results of surgery. Despite these advances, adverse effects of CPB are important and well documented.1,2 Beating heart myocardial revascularization was introduced to offset the disadvantages of CPB, with the promise of reductions in the inflammatory reaction, complications, postoperative bleeding and incidence of organ dysfunction.2 However, even with the use of off-pump techniques, there remains a group of patients with low ejection fraction (EF), left main stenosis, or unstable angina in whom a brief hemodynamic derangement may have serious consequences, leading to incomplete revascularization or conversion to CPB with less satisfactory results.3 We adopted a simple technique of left ventricular (LV) assistance with the intent of offering the advantages of both CPB and off-pump revascularization to this small group of difficult patients.
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TECHNIQUE
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All operations are performed through a median sternotomy. A cell saver (Fresenius HemoCare GmbH, Bad Homburg, Germany) is routinely used. The pericardium is opened and the internal thoracic arteries (ITAs) are harvested as pedicled conduits; bilateral ITA harvesting is avoided in patients with age > 60 years, insulin-dependent diabetes, obesity or chronic obstructive pulmonary disease. Simultaneously, the radial artery in the nondominant arm, and/or the saphenous vein are harvested. The patients are heparinized with an initial dose of 1 mg·kg–1 heparin and an activated clotting time of more than 300 sec is obtained and maintained throughout the operation. A double pursestring suture is placed on the ascending aorta, and a 20F–22F arterial cannula (DLP; Medtronic, Minneapolis, MN, USA) is introduced into the ascending aorta. A pursestring suture is placed near the right pulmonary vein and under water seal, a 24F venous cannula (DLP; Medtronic) is introduced into the left atrium and advanced to the left ventricle. The two cannulas are connected to a centrifugal pump (Jostra, em-tec GmbH, Gewerbering, Germany) without an oxygenator or heater/cooler and placed near the patient’s head. Therefore, the tubing length is < 100 cm, and the priming volume is reduced (120 mL). On starting the system, blood is sucked from the left ventricle and pumped into the aorta; a flow of 2–4 L·min–1 is obtained, achieving normal cardiac output and hemodynamic stability throughout the procedure.
The occurrence of ST segment elevation, ventricular arrhythmia, or hemodynamic instability may dictate the institution of ventricular support shortly after opening the sternum and before the arterial conduits have been completely harvested. In this way, all the arterial conduits are isolated without duress, and the arterial anastomoses (radial artery and/or right internal thoracic artery on the left internal thoracic artery) may be performed securely and calmly. To facilitate cardiac elevation and coronary vessel exposure, a deep pericardial suture is placed near the right pulmonary vein and the superior vena cava, and secured to a tape. To reduce the amplitude of ventricular wall movement, a suction-type mechanical stabilizer (Octopus; Medtronic) is used. The coronary artery is exposed and incised, and vascular control is obtained with an intracoronary shunt (Viewline; Medtronic). A blower-mister is routinely used to achieve a bloodless field. We routinely construct an arterial Y-graft with 8/0 polypropylene continuous sutures. First, the distal anastomoses are constructed with a continuous 7/0 polypropylene suture. The proximal anastomoses on the ascending aorta (if needed) are then performed using a single partial clamp and a 6/0 continuous polypropylene suture. At the end of the procedure, the cannulas are easily removed and protamine is given.
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RESULTS
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Fifty-six patients were treated for coronary artery disease with a technique employing central cannulation and LV assistance. Patient characteristics and postoperative results are summarized in Table 1
. The majority of patients were taken to the operating room with a preoperative status of unstable angina and ST-segment elevation, or with a critical left main lesion and an occluded right coronary artery. Six patients underwent institution of LV assistance shortly after sternotomy because of severe hemodynamic instability. No device-related complications occurred during the procedures. All patients underwent the planned complete myocardial revascularization, and none required conversion to conventional CPB. A mean of 3.4 grafts per patient were constructed. One patient developed ventricular fibrillation during the procedure, which was readily cardioverted while the centrifugal pump maintained a flow of 2 L·min–1. Importantly, the heart did not distend.
Weaning from left heart support was uncomplicated and only one patient required an intra-aortic balloon pump after surgery for a low cardiac output state, and this resolved within a few hours. No patient suffered a postoperative neurological complication. There were 2 deaths in patients with a preoperative EF < 30%.
Complete myocardial revascularization had been achieved in both cases and they did well in the early postoperative period, but pulmonary infection and multi-organ failure subsequently developed in both of them, and they died on the 12th and 23rd postoperative day. All other patients were discharged from the hospital in good condition. One patient died suddenly at home 2 months later. This patient had a preoperative EF of 20%, and after undergoing complete and uneventful quintuple bypass, had been discharged from the hospital in good health. The remaining patients are in good condition and have shown improved EF on echocardiography.
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DISCUSSION
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The field of coronary revascularization is evolving. Excellent results have been achieved for both percutaneous and open heart procedures. The high-risk patient, often defined as either elderly, hemodynamically unstable, having a low EF or manifesting serious comorbidities, may not be a candidate for percutaneous intervention. Therefore, surgical procedures that might reduce the untoward effects of CPB or permit beating heart surgery to be performed more easily, have been advocated by some surgeons. Off-pump myocardial revascularization was introduced with the aim of avoiding many of the drawbacks of conventional CPB. The early proponents of off-pump revascularization limited their surgery to the left anterior descending and right coronary arteries, but at present, with the aid of mechanical stabilizers and positioners, all coronary vessels may be reached and anastomoses may be performed with what has been claimed by some as the same quality as that performed on the arrested heart.4,5
Despite a sizable experience with off-pump surgical techniques, there remains a small group of patients with unstable angina and/or unfavorable anatomy (intramyocardial or calcified coronary arteries) in whom off-pump surgery may require urgent conversion to on-pump surgery. Altering the planned surgical procedure not infrequently results in fewer vessels revascularized, fewer arterial conduits used, and a poor postoperative course with an increased complication rate.3 Beating heart LV-assisted myocardial revascularization may be an alternative surgical procedure for this group of patients. We contend that this technique delivers the advantages of both beating heart surgery and CPB, while reducing the drawbacks of either technique. Left heart assistance allows for decompression of the left ventricle, facilitating manipulation, positioning, and stabilization of the heart without the need to apply an aortic crossclamp or to deliver cardioplegia. Lung ventilation continues throughout the procedure. Right heart distension has not been observed and is likely the result of LV decompression and low LV end-diastolic pressure, permitting more favorable unloading conditions for the right heart. Beating heart LV-assisted coronary revascularization lessens the risk and the cost of conventional CPB by eliminating the oxygenator and the cardiotomy reservoir, and by reducing tubing length. Moreover, the patient’s own lungs are perfused and ventilated, thus avoiding stasis and reperfusion injury.6 The priming volume is reduced which reduces hemodilution and the need for transfusion. The risk of air embolism is negligible because the left ventricle is not completely unloaded during CPB and, therefore, air entrapment is avoided. In addition, the initiation of LV assistance as described herein is unlike the initiation of true LV assist device support where the patient is already on CPB with the LV decompressed, and maneuvers to avoid air entrapment around the inflow cannula must be employed.
We have found that in selected unstable or technically challenging situations, the use of a readily implantable, low-cost and low-prime LV support system allows the surgeon to complete the planned surgical procedure on the decompressed beating heart. The procedure may then be completed without the need for full anticoagulation or a large-volume prime CPB circuit, with the increased likelihood of hemodilution and risk of transfusion, or the challenge of maintaining stable hemodynamics seen with off-pump surgery, comfortably and reliably positioning, and stabilizing the fully distended heart for revascularization.
Presented at the 17th Biennial Congress of the Association of Thoracic and Cardiovascular Surgeons of Asia, Manila, Philippines, November 20–23, 2005.
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ACKNOWLEDGMENTS
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We thank R Michler, MD, for editing the manuscript.
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REFERENCES
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[Abstract]
[Full Text]
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ABSTRACT
INTRODUCTION
