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Ann Thorac Surg 1998;66:1036-1040
© 1998 The Society of Thoracic Surgeons

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Supplement

Minimally invasive coronary artery bypass grafting: port-access approach versus off-pump techniques

^a Department of Cardiac Surgery, University Hospital Munich-Grosshadern, Munich, Germany

Address reprint requests to Dr Reichenspurner, Department of Cardiac Surgery, University Hospital Munich-Grosshadern, Marchioninistr 15, D-81377 Munich, Germany
e-mail: (hcr{at}hch.med.uni-muenchen.de)

Presented at "Facts and Myths of Minimally Invasive Cardiac Surgery: Current Trends in Thoracic Surgery IV," New Orleans, LA, Jan 24, 1998.

Abstract

Background. Within the past 5 years several surgical techniques have been developed for less invasive surgical treatment of coronary artery disease. The aim of this study was to define specific indications for the various minimally invasive coronary artery surgical procedures.

Methods. Minimally invasive direct coronary artery bypass grafting through a minithoracotomy was performed in 67 patients. The left internal mammary artery was anastomosed on the beating heart with the use of a pressure or suction stabilizer without the use of extracorporeal circulation. In 58 other patients with multivessel disease, the off-pump coronary artery bypass grafting technique through a sternotomy was applied with a left internal mammary artery to left anterior descending artery and additional vein grafts without extracorporeal circulation. In a third group, Port-Access (Heartport Inc, Redwood City, CA) coronary artery bypass grafting was performed through a left minithoracotomy with the use of an endovascular extracorporeal circulation system and cardioplegic arrest. Angiographic follow-up was complete in 64% of the patients.

Results. There was minimal perioperative or postoperative mortality (0.5%). The medium surgical procedure time for all minimally invasive and off-pump procedures was 2.5 hours; it was 4.5 hours for Port-Access procedures. The median postoperative intensive care unit stay was 1.0 days, and the median hospitalization was 5.0 days. Overall graft patency was 97.3%; in 8 patients (4.1%) a stenosis either at or distal to the graft anastomosis was dilated with coronary angioplasty.

Conclusions. For single-vessel disease of the left anterior descending artery, the minimally invasive coronary artery bypass grafting procedure can be performed safely without the use of extracorporeal circulation. In case of hemodynamic instability or anatomic variation, the Port-Access procedure can be applied without additional necessity for sternotomy. For multivessel disease, the off-pump bypass grafting procedure with sternotomy can be recommended depending on the coronary arteries involved. In case of necessary grafts to the lateral marginal or circumflex branches, Port-Access grafting can be recommended and may play an important role in the future for the development of fully endoscopic robot-assisted coronary artery bypass grafting.

Within the past few years several techniques have been developed to allow the performance of less invasive cardiac surgical procedures for the treatment of a variety of cardiac diseases. For coronary artery bypass grafting (CABG), different options are available: One technique allows the coronary artery surgical procedure to be done through a small thoracic access and uses an endovascular bypass system to allow extracorporeal circulation and cardioplegic arrest (Port-Access [Heartport Inc, Redwood City, CA] CABG). This system requires femoral arterial and venous access for cardiopulmonary bypass (CPB) and the use of a transfemoral endoaortic occlusion catheter (Endoaortic Clamp; Heartport Inc) for aortic occlusion, root venting, and application of antegrade cardioplegia. After extensive animal studies, a phase I Food and Drug Administration trial was performed at the Stanford University School of Medicine [1, 2]. In March 1996, a clinical program of Port-Access CABG was started at the University of Dresden [3].

Several surgeons in South America, Italy, and the United States started to do CABG through small accesses on the beating heart. This technique was first published by Kolessov in 1967 [4]. In 1994, Benetti and associates [5, 6] described the preparation of the left internal mammary artery (LIMA) through a small anterior thoracotomy and the performance of an LIMA to left anterior descending artery (LAD) anastomosis on the beating heart without the use of CPB. This procedure has been termed minimally invasive direct coronary artery bypass (MIDCAB; Cardiothoracic Systems, Inc, Cupertino, CA). Furthermore, using different accesses, such as partial or total sternotomy, multivessel revascularization was introduced using off-pump techniques [7].

Patients and methods

Port-access coronary artery bypass grafting
In our first study performed between March 1996 and February 1997, 42 patients with isolated significant lesions of the LAD were treated with Port-Access CABG at the University of Dresden [3]. Since February 1997 another 17 patients have been operated on with this technique at the University of Munich. Twelve patients had single-vessel and 5 patients had multivessel coronary artery disease. The various coronary arteries revascularized with the Port-Access technique were as follows: LAD, 54; LAD + intermediate branch, 2; LAD + circumflex artery, 2; and LAD + circumflex artery + posterior descending artery, 1. The median age of the patients was 58 ± 12.5 years (range, 31 to 78 years); 45 patients were male and 14 were female. The preoperative left ventricular ejection fraction ranged from 0.35 to 0.78 (median ± standard error, 0.65 ± 0.2). All patients suffered from angina pectoris and were mainly in Canadian Cardiovascular Society stage 2 or 3.

All the patients underwent preoperative assessment of the abdominal aorta and the iliac and femoral arteries with Doppler sonography. In addition, transesophageal echocardiography (TEE) was performed in all patients to evaluate the condition of the ascending and descending aorta to exclude severe atherosclerotic disease of the aorta and major aortic valve incompetence.

The endovascular CPB system used consisted of a Y-shaped femoral arterial return cannula, a femoral venous cannula for drainage of the right atrium, an Endopulmonary Vent Catheter and an endoaortic balloon occlusion catheter (Endoaortic Clamp; Heartport Inc) (Fig 1).

View larger version (37K): [in this window] [in a new window]   Fig 1. Endovascular cardiopulmonary bypass system consisting of Endovenous Drainage Cannula, Endopulmonary Vent catheter, Endocoronary Sinus Catheter (if needed), and endoaortic occlusion catheter (Endoaortic Clamp) (Heartport Inc, Redwood City, CA).

The patient was placed in a supine position with the left shoulder being elevated about 30 degrees. The patient was prepared and draped in such way that the whole chest and both groins were accessable in case the operation had to be converted to a conventional procedure with median sternotomy.

A small (5 to 8 cm; median, 7.5 cm) incision was made parasternally above the fourth intercostal space. The LIMA was dissected distally down to below the sixth rib and proximally up to the first rib with preparation, ligation, and division of all the major side branches including the second intercostal branch in all patients and the first intercostal branch in 50% of the patients.

As the LIMA was being prepared, the femoral vessels were dissected through a small incision made above the right groin and surrounded by umbilical tapes. The Y-shaped femoral arterial return cannula was placed into the femoral artery. A long (100 mm) guidewire was used to ensure correct placement of the arterial canula. Thereafter, the 28F venous cannula was inserted into the femoral vein and positioned in the right atrium under TEE control. The Endoaortic Clamp was placed with a guidewire through the second opening of the Y-shaped arterial cannula. The guidewire and the occlusion catheter were moved forward into the descending and ascending aorta under fluoroscopic and TEE control.

After correct placement of the Endoaortic Clamp, CPB was started. The pericardium was then incised above the LAD and the incision was extended proximally above the ascending aorta. Pericardial stitches were placed left and right to the ascending aorta and stitched to the skin incision in that way that the ascending aorta became visible and pulled toward the skin incision. In our experience of multivessel Port-Access CABG, the proximal anastomoses of the vein grafts were performed first, with use of a side-biting clamp on the ascending aorta (Fig 2). Thereafter the balloon of the Endoaortic Clamp was inflated with diluted radiocontrast agent. The balloon was placed 2 cm above the aortic valve with careful monitoring of the right radial artery pressure to avoid occlusion of the bracheocephalic trunk. After full inflation of the balloon, the balloon pressure and the aortic root pressure were monitored continuously. Cardioplegia was then administered through the proximal end of the Endoaortic Clamp and cardioplegic arrest was achieved. After the administration of cardioplegia, additional root venting was achieved through the distal end of the Endoaortic Clamp catheter.

View larger version (144K): [in this window] [in a new window]   Fig 2. Performance of a proximal anastomosis in a Port-Access (Heartport Inc, Redwood City, CA) coronary artery bypass grafting procedure through a small anterior thoracotomy.

Beating heart techniques
Minimally invasive coronary artery bypass grafting
Sixty-seven patients were operated with the MIDCAB technique (median age ± standard error, 55.3 ± 8.5 years; 48 men and 19 women). The position and draping of the patient and preparation of the LIMA were done as in Port-Access CABG. After preparation of the LIMA, a special thoracic retractor was used in combination with a pressure stabilizer (Cardiothoracic Systems, Inc) to achieve stabilization of the LAD. The LAD was surrounded proximal and distal to the region of the anastomosis with 5.0 Prolene (Ethicon, Somerville, NJ) stitches. After initial occlusion of the LAD, the ECG and TEE were checked for signs of major myocardial ischemia. After achievement of correct stabilization and a bloodless surgical field, the LIMA to LAD anastomosis was performed on the beating heart with 7.0 Prolene sutures.

Octopus technique
For multivessel beating heart revascularization, the Octopus suction stabilizer (Medtronic GmbH, Düsseldorf, Germany) was used (Fig 3). A total of 58 patients (39 men and 19 women; median age ± standard error, 62.5 ± 6.8 years) underwent coronary revascularization of the following vessels: LAD, 13; LAD + diagonal artery, 10; LAD + intermediate branch, 5; LAD + obtuse marginal branch, 3; LAD + right coronary artery, 22; and LAD + diagonal artery + right coronary artery, 5.

View larger version (124K): [in this window] [in a new window]   Fig 3. The Octopus (Medtronic GmbH, Düsseldorf, Germany) system used for mechanical stabilization of the coronary arteries.

Data collection
In all patients, irrespective of the surgical technique used, the intraoperative data (total operative time, LIMA harvesting time, duration of CPB, duration of cardioplegic arrest, and duration of coronary ischemia in the beating heart cases) were carefully monitored. After each patient’s transferral to the intensive care unit, the duration of ventilation, length of intensive care unit stay, and total hospital stay were also recorded. The patients were followed up until their discharge, and any intraoperative and perioperative complications were recorded. Angiographic follow-up was obtained in 64% of the patients after the operation.

Results

The intraoperative and postoperative data for the Port-Access CABG group, the MIDCAB group, and the Octopus group are listed in Table 1. Combining our experience with Port-Access CABG at the University of Dresden [3] and the University of Munich, 58 of the 59 patients survived and recovered well (98.3%). As a major complication, one retrograde aortic dissection occurred; the first generation of Endoaortic Clamps was used in this patient, who had also preoperative evidence of peripheral vascular disease. Since the second generation of Endoaortic Clamps was introduced in October 1996 and used, no further arterial dissection has been observed. In addition, one iliac artery dissection occurred and 1 patient required femoral artery patch reconstruction after removal of the arterial cannula. All other complications recorded were minor and comprised small wound infections (n = 3), pleural effusions (n = 3), postoperative hemorrhage (n = 3), and lymphatic fistula in the groin (n = 2). Furthermore, 1 patient had a transient hemiparesis for 24 hours, probably caused by an air embolism, followed by complete recovery. At postoperative angiography, the studies revealed patent anastomoses in 98%; 3 patients had evidence of diffuse stenotic LAD disease either at the site of the anastomosis (n = 1) or distal to the anastomosis (n = 2), which was treated successfully with subsequent percutaneous transluminal coronary angioplasty (see Table 1). No patient required a reoperation.

Similar results were achieved in the off-pump CABG group. All patients survived the operation. In 2 patients (9%) the procedure was converted to include cardiopulmonary bypass intraoperatively because of the development of severe bradycardia and hemodynamic insufficiency, which occurred during occlusion of the right coronary artery. No other complication was observed in the perioperative follow-up. At angiographic control, 53 of the 54 grafts (98%) showed patent anastomoses; 4 patients required a subsequent PTCA because of a narrowing within the region of or distal to the LAD anastomosis (see Table 1).

Comment

In comparison with conventional CABG, there are currently several different less invasive surgical procedures available. The Port-Access technique enables the surgical treatment of single-vessel and multivessel coronary artery disease through small thoracic incisions with the use of an endovascular CPB system. Our experience is based on 59 Port-Access CABG operations with a mortality of 1.7% and an anastomotic patency at follow-up of 98% [3]. The incidence of retrograde aortic dissections in the total population was 1.6%. Since the exclusion of patients with peripheral vascular disease and the use of the second-generation Endoaortic Clamp in the last 65 cases, arterial or aortic dissection has been avoided completely. It is important to note that evidence of major peripheral vascular disease is a contraindication to the use of the Port-Access system.

The Port-Access Registry currently reports on more than 600 Port-Access CABG procedures including 57% single-vessel and 43% multivessel revascularizations. The report from the Port-Access Registry [8] shows a mean procedure time for single-vessel CABG of 4.2 hours; double-vessel CABG, 4.8 hours; and triple-vessel CABG, 5.4 hours. The median length of stay was 4.0 days for all three revascularization procedures. The mortality within the Port-Access procedures was 1.9%; the stroke rate, 1.6%; the rate of myocardial infarction, 1.1%; and the incidence of new-onset atrial fibrillation, 6.7%.

The advantage of the Port-Access technique is that because of the use of CPB and cardioplegic arrest, all coronary arteries can be reached for revascularization through a small anterior thoracotomy. The anastomoses can safely be performed on the arrested heart, and the myocardium is protected during the surgical procedure. In addition, the ascending aorta can be mobilized and also proximal bypass anastomoses can be performed through the same incision. Because the operation itself is done through limited incisions, the patients usually can be mobilized faster and discharged earlier when compared with regular CABG patients [3]. A possible disadvantage is the risk of arterial injury, particularly in patients with peripheral vascular disease. The operating times are currently still longer and additional costs for material and staff arise when this procedure is used.

In addition to the Port-Access method, beating heart surgical techniques are applied for single-vessel and multivessel coronary revascularization without the use of CPB. The MIDCAB procedure through a small anterior thoracotomy is currently used for anterior wall revascularization, such as LAD or LAD + diagonal artery. These coronary arteries can be easily reached through this incision and stabilized well by either pressure or suction stabilizers. Tourniquet sutures help to achieve an almost bloodless field for the time of the anastomosis. In case of some residual bleeding, a combined blowing and spraying device can be used to enable safe grafting. Worldwide, more than 3,000 MIDCAB procedures have been performed. In recent publications, the mortality after MIDCAB procedures ranges between 0.6% and 2.3%. At angiographic follow-up, the patency rate of the anastomosis is reported to be between 92% and 100% [6, 9]. Thus, particularly for single-vessel revascularization of the LAD, the MIDCAB procedure can be recommended without any significant increase in perioperative morbidity or mortality or any compromise in anastomosis quality. However, as a backup procedure in case of an intramyocardial LAD or severe hemodynamic deterioration during occlusion of the LAD, the Port-Access CABG method can be highly recommended instead of conversion of the procedure to a full sternotomy with regular CPB.

Multivessel revascularization using the Octopus suction stabilizers is possible. The mortality in recent reports is 0%, and the patency rate of the performed anastomoses is 95% [7]. Some of the coronary arteries, such as lateral marginal or circumflex artery branches are, however, more difficult to access using these stabilizers. Experienced surgical skills are necessary for these cases, and care must be taken to perform anastomoses with good quality. Particularly during occlusion of the right coronary artery, bradycardia and hemodynamic instability is not uncommon, necessitating a conversion to CPB. The use of intracoronary shunts might improve this conversion rate [10].

In conclusion, these different less invasive techniques for coronary artery bypass grafting are not necessarily competitive but should rather be used according to the specific indication. The MIDCAB procedure is an ideal technique for revascularization of coronary single-vessel disease involving the LAD and the diagonal branches. For multivessel revascularization, both the beating heart (off-pump) method and the Port-Access CABG technique can be safely performed without significant perioperative morbidity or mortality. With use of the Octopus technique, CPB can be avoided and most of the coronary arteries can be reached through a partial or full median sternotomy. Port-Access CABG offers the advantage of a limited access and, with use of CPB and cardioplegic arrest, allows a safe anastomosis to be performed on any coronary artery. Port-Access CABG allows further development of new, even less invasive techniques and is a very valuable option for the performance of true endoscopic robot-assisted coronary artery surgery in the near future. In addition, Port-Access CABG is an excellent backup technique for MIDCAB procedures without the necessity of a full sternotomy.

Footnotes

¹ Doctor Reichenspurner worked as a clinical consultant for Heartport Inc, Redwood City, CA.

References

1. Stevens J.H., Burdon T.A., Peters W.S., et al. Port-Access coronary artery bypass grafting: a proposed surgical method. J Thorac Cardiovasc Surg 1996;111:567-573.[Abstract/Free Full Text]
2. St. Goar F.G., Siegel L.C., Stevens J.H., et al. Catheter based cardioplegic arrest facilitates Port-Access cardiac surgery. Circulation 1996;94(Suppl 1):52.[Abstract/Free Full Text]
3. Reichenspurner H., Gulielmos V., Wunderlich J., et al. Port-Access coronary artery bypass grafting with the use of cardiopulmonary bypass and cardioplegic arrest. Ann Thorac Surg 1998;65:413-419.[Abstract/Free Full Text]
4. Kolessov V.I. Mammary artery-coronary anastomosis as a method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967;54:535-544.[Medline]
5. Benetti F.J., Ballester C. Uso de la tarascopia en cirurgia coronaria para diseccion de la mammaria interna. Brensa Med Argent 1994;81:877-879.
6. Benetti F., Mariani M.A., Sanig G., et al. Video assisted minimally invasive coronary operations without cardiopulmonary bypass: a multicenter study. J Thorac Cardiovasc Surg 1996;112:1478-1484.[Abstract/Free Full Text]
7. Jansen E.W.L., Gründeman P.F., Borst C., et al. Less invasive off-pump CABG using a suction device for immobilization: the "Octopus" method. Eur J Cardiothorac Surg 1997;12:406-412.[Abstract/Free Full Text]
8. Siegel L. The Port-Access Registry. Presented at the Stanford Symposium on Minimally Invasive Cardiac Surgery, La Quinta, CA, Oct 24–25, 1997.
9. Calafiore A.M., Di Giammarco G., Teodori G., et al. Left anterior descending coronary artery grafting via left anterior small thoracotomy without cardiopulmonary bypass. Ann Thorac Surg 1996;61:1658-1663.[Abstract/Free Full Text]
10. Rivetti L.A., Gandra S.M.A. An intraluminal shunt for off-pump coronary artery bypass grafting. Report of 501 consecutive cases and review of the technique. Heart Surg Forum 1998;1:30-36.[Medline]

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