Asian Cardiovasc Thorac Ann 1999;7:93-95
© 1999 Asia Publishing EXchange Pte Ltd
Management of Cardiopulmonary Bypass During Minimally Invasive Cardiac Surgery
Bao Mei, MD,
Geng Jian Ying, MD,
Guo Bin, MD
Department of Cardiothoracic Surgery
Bethune International Peace Hospital
Hebei, People's Republic of China
|
|
For reprint information contact: Bao Mei, MD Tel: 86 311 799 8519 email: ctsgb{at}public.sj.he.cn Department of Cardiothoracic Surgery, Bethune International Peace Hospital, Shijiazhuang, Hebei 050082, People's Republic of China.
|
 |
Abstract
|
|---|
From December 1996 to December 1997, 58 patients underwent minimally invasive cardiac surgery in our institute. The operations comprised 10 for atrial septal defect, 26 for ventricular septal defect, 15 for mitral stenosis and insufficiency, 4 for aortic valve insufficiency, 2 for left atrial myxoma, and 1 for right ventricular myxoma. There were 21 men and 37 women with a mean age of 20 years (range, 5 to 46 years) and a mean weight of 35 kg (range, 15 to 68 kg). To establish cardiopulmonary bypass, femorofemoral and superior vena caval cannulation or femoral artery and two-stage cannulation was used. Normothermia with a beating heart or moderate hypothermia with aortic cross-clamping during cardiopulmonary bypass were employed. All patients resumed sinus rhythm spontaneously, except for one who was easily defibrillated. There were no deaths or neurologic complications and no problems with the cannulation sites. We concluded that these techniques of cardiopulmonary bypass were feasible and safe.
|
Introduction
|
|---|
Since the early 1980s, it has become evident that less invasive methods of surgery have produced fewer complications and reduced the incidence of mortality and morbidity.1 Minimally invasive cardiac surgery, defined as avoidance of a large sternotomy incision, with or without the use of cardiopulmonary bypass (CPB), has developed rapidly.2 Although coronary artery bypass grafting via a small incision can be performed without CPB, the heart-lung machine is essential for many other cardiac operations.3,4 Methods of cannulation and management of CPB must be modified to suit the different surgical approaches in minimally invasive cardiac surgery. We describe two methods of establishing CPB for a variety of cardiac operations performed via a small incision.
|
Patients and Methods
|
|---|
From December 1996 to December 1997, 58 patients underwent minimally invasive cardiac surgery in our institute. The operations comprised 10 for atrial septal defect, 26 for ventricular septal defect, 15 for mitral stenosis with mitral valve insufficiency, 4 for aortic valve insufficiency, 2 for left atrial myxoma, and 1 for right ventricular myxoma. There were 21 men and 37 women with a mean age of 20 years (range, 5 to 46 years) and a mean weight of 35 kg (range, 15 to 68 kg).
During surgery, patients were usually placed in the supine position and a right parasternal incision of 10 cm was made. CPB was employed under normothermic conditions with a beating heart in the 10 cases of atrial septal defect repair and under conditions of moderate hypothermia with aortic cross-clamping for the other operations. In the normothermic beating-heart group, the priming solution was pre-warmed to between 34°C and 36°C before CPB. At the onset of CPB, lidocaine hydrochloride (1 to 2 mg•kg–1) was given via the reservoir, the radial artery pressure was monitored and kept at more than 50 mm Hg. Hemodilution was maintained at 35 mL•kg–1, and the full bypass flow rate was set at 2 to 2.6 L•m–2•min–1.
In the moderate hypothermia group, hemodilution was maintained at 40 to 50 mL•kg–1 and cardioplegia was delivered via the aortic root. Initially, cold crystalloid cardioplegic solution was infused at a rate of 20 mL•kg–1, followed by cold blood cardioplegia at a rate of l0 mL•kg–1. The period of hypothermic infusion was 15 to 20 minutes, followed by warm blood infusion at a rate of 5 to 10 mL•kg–1 before declamping the aorta. Lidocaine hydrochloride (1 to 2 mg•kg–1) was administered before declamping the aorta and the mean radial artery pressure was monitored and maintained between 40 and 80 mm Hg during CPB.
Extracorporeal circulation was established using two methods of cannulation. Femoral artery and two-stage venous cannulation was used for aortic valve replacement; a standard femoral artery cannula was inserted and a venous cannula was placed in the right atrial appendage. Standard femorofemoral and superior vena caval cannulation was used in the other cases and adequate venous drainage was obtained by placing a right-angled venous cannula in the superior vena cava and inserting a long venous cannula into the inferior vena cava from the common femoral vein. After initiation of CPB, the superior and inferior venae cavae were snared, the aorta was cross-clamped, and antegrade cardioplegia was administered. Before declamping the aorta, air was removed from the heart through the aortic incision in aortic valve replacement patients and through an atrial septal incision from the left side of the heart in other patients. The circuit was primed with polygeline (Haemaccel; Behringwerke AG, Marberg, Germany), Ringer's lactate solution, and whole blood. Clean priming was used if the patient's body weight was more than 25 kg and the hematocrit was normal. When the patient's body weight was more than 60 kg and the hematocrit was normal, autologous blood (10% to 15% of the blood volume calculated from body weight) was obtained before CPB.
|
Results
|
|---|
The duration of CPB ranged from 34 to 123 minutes (mean, 67 minutes), aortic cross-clamp time was 14 to 74 minutes (mean, 44 minutes). All patients resumed sinus rhythm spontaneously, except for one who was easily defibrillated. Mechanical ventilation was maintained for 4 to 12 hours postoperatively and intensive care stay ranged from 2 to 4.5 days (mean, 3.6 days). There was less trauma and these patients reported less pain than those undergoing sternotomy. There were no postoperative complications, all patients recovered without evidence of neurologic dysfunction, and there were no problems related to the cannulation sites.
|
Discussion
|
|---|
Minimally invasive surgery is one of the great innovations of healthcare in the 20th century.5 In cardiac surgery, a smaller incision has many potential advantages; there is less trauma and less pain reported by the patients, and it reduces the risks of wound infection and blood loss. The traditional methods of cannulation for CPB have to be modified for minimally invasive cardiac surgery because of the small incision. In our practice, two methods of cannulation were performed; femorofemoral and superior vena caval CPB was instituted for patients with a body weight of more than 15 kg, femoral and two-stage cannula was applied in patients undergoing aortic valve replacement. To insure adequate perfusion, the arterial cannula should be as large as possible and the femoral vein cannula must be inserted into the inferior vena cava for sufficient drainage.
In the situation of a beating heart during CPB, it is important to maintain optimal arterial pressure and to avoid arrhythmias. Although some perfusionists have reported that phenylephrine can prevent hypotension during CPB, others consider that it can cause abnormal regional perfusion during normothermic bypass and should be avoided.6–8 In our series, the mean radial artery pressure was maintained at more than 60 mm Hg before CPB and the priming solution was kept at 34°C to 36°C. Lidocaine was added to the reservoir and the pump flow rate was increased step by step, starting with one third of the full bypass flow, increasing to half, and then to full flow. Increments in pump flow rate were dependent on blood pressure and heart rhythm.
Exposure of the heart in minimally invasive cardiac surgery is limited compared to conventional open heart procedures and the filling condition of the heart cannot be observed directly or clearly. The blood volume should be increased slowly according to the mean radial pressure, central venous pressure, and urine output after aortic declamping, to avoid overfilling of the heart.
De-airing was not found to be difficult in our experience of minimally invasive surgery. Adequate removal of air was achieved by filling the heart with blood or saline before closure of the aortic or atrial septal incision. It was necessary for the anesthetist to expand both lungs to displace air from the left atrium, pulmonary veins, and ventricle. Aortic root venting and placing the patient in a head-down position were also useful for removing residual air from the heart. All patients in this series woke promptly after arrival in the intensive care unit without evidence of air embolization.
Lower extremity ischemia and necrosis have been reported in some patients after CPB via femoral cannulation.9 In our group, the maximum duration of CPB was 123 minutes and there were no complications related to the femoral cannulation sites. We concluded that these techniques of cardiopulmonary bypass were feasible and safe.
|
References
|
|---|
-
Wickham JEA. Minimally invasive surgery. BMJ 1994;308:193–6.[Free Full Text]
-
Lytle BW. Minimally invasive cardiac surgery. J Thorac Cardiovasc Surg 1996;111:554–5.
-
Navia JL, Cosgrove DM III. Minimally invasive mitral valve operations. Ann Thorac Surg 1996;62:1542–4.[Abstract/Free Full Text]
-
Emery RW, Emery AM, Flavin TF, Nissen MD, Mooney MR, Arom KV, et al. Revascularization using angioplasty and minimally invasive techniques documented by thermal imaging. Ann Thorac Surg 1996;62:591–3.[Abstract/Free Full Text]
-
Banta HD. Minimally invasive surgery. Implications for hospitals, health workers, and patients. BMJ 1993;307:1546–9.
-
Martin TD, Craver JM, Gott JP, Weintraub WS, Ramsay J, Mora CT, et al. Prospective, randomized trial of retrograde warm blood cardioplegia: myocardial benefit and neurologic threat. Ann Thorac Surg 1994;57:298.[Abstract]
-
Singh AK, Bert AA, Feng WC, Rotenberg FA. Stroke during coronary artery bypass grafting using hypothermic versus normothermic perfusion. Ann Thorac Surg 1995;59:84–9.[Abstract/Free Full Text]
-
O'Dwyer C, Woodson LC, Conroy BP, Lin CY, Deyo DJ, Uchida T, et al. Regional perfusion abnormalities with phenylephrine during normothermic bypass. Ann Thorac Surg 1997;63:728–35.[Abstract/Free Full Text]
-
van der Salm TJ. Prevention of lower extremity ischemia during cardiopulmonary bypass via femoral cannulation. Ann Thorac Surg 1997;63:251–2.[Abstract/Free Full Text]
TOP
Abstract
Introduction
