Eur J Cardiothorac Surg 1998;14:S31-S37
© 1998 Elsevier Science NL
Mammary coronary artery anastomosis without cardiopulmonary bypass through minithoracotomy: one year clinical experience 1
Yugal Mishra*,
Yatin Mehta,
Sanjay Mittal,
Mahendra Mairal,
Anil Karlekar,
Ashok Seth,
Tarlochan Singh Kler,
Naresh Trehan
Escorts Heart Institute and Research Centre, Okhla Road, New Delhi 110 025, India
* Corresponding author. Tel.: +91 11 6844820/6833641/6838889; fax: +91 11 6832506; e-mail: ehirc@giasd1.01.vsnl.net.in
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Abstract
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Objective: The recent concept of minimally invasive coronary artery surgery in selected patients has dramatically affected surgical management of coronary artery disease. We explored the possibility of coronary artery bypass grafting of anterior coronary arteries with in situ internal mammary artery through a limited anterior thoracotomy on beating heart. Method: Minithoracotomy and direct coronary artery surgery without cardiopulmonary bypass (CPB) was attempted in 116 patients. The procedure was completed in 108 cases while in eight cases minithoracotomy was converted to mid sternotomy. In 107 cases, left internal mammary artery (LIMA) to left anterior descending (LAD) coronary artery anastomosis was done through left anterior minithoracotomy and in one case LIMA to LAD and right internal mammary artery (RIMA) to right coronary artery (RCA) anastomosis was done through bilateral minithoracotomy. Left anterior minithoracotomy through 4th intercostal space and right anterior minithoracotomy through 5th intercostal space was used for left and right internal mammary artery dissection respectively. With this approach 4–8 cm length of mammary artery was easily dissected. Mammary coronary artery anastomosis were performed on a beating heart without CPB through window pericardiotomy. Two patients also underwent left carotid endarterectomy along with LIMA to LAD anastomosis. In two patients complementary percutaneous transluminal coronary angioplasty (PTCA) to circumflex artery was done 5 days after minithoracotomy and LIMA to LAD anastomosis. Results: Forty-two patients were extubated in the operating room and 66 in the intensive care unit 2–10 h after surgery. Blood transfusion was used in one case who was reexplored for postoperative bleeding due to a displaced hemoclip from the internal mammary artery branch. None of these patients required inotropic support. Postoperative predischarge check angiogram in 53 cases revealed adequate mammary coronary flow in 51 cases, the remaining two had anastomotic problems, one was subjected to PTCA and the other for redo coronary bypass grafting through mid sternotomy. Doppler flow assessment of anastomosis was done in 102 cases, of which two showed problems which was confirmed on check angiography. One-hundred and six patients are in our regular follow-up (mean follow-up 10±1.5 months), 98 of them are in functional class I. Conclusion: In our experience mammary coronary artery anastomosis without CPB through minithoracotomy is a safe, simple and minimally invasive procedure. Favorable cost/benefit ratio, has been achieved due to no early/late mortality and minimal early morbidity. Postoperative check angiogram and Doppler flow study revealed excellent mid term results.
Key Words: Minimally invasive coronary artery surgery • Minithoracotomy • Without cardiopulmonary bypass • Mammary coronary artery anastomosis
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1. Introduction
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Cost containment and reducing risks of conventional coronary artery bypass graft surgery (CABG) has led to myocardial revascularization without cardiopulmonary bypass (CPB) in selected cases [2, 5, 7, 16]. The use of a left thoracotomy to graft one or more coronary arteries was the first approach to revascularize myocardium with the help of internal mammary artery [11]and is today widely used in redo operations [4]. In an attempt to further reduce the invasiveness of coronary artery bypass grafting and retain the benefit of mammary artery grafting, the mini-anterior mediastinal approach [17], partial sternotomy approach and minilateral thoracotomy [19]have recently been described.
Harvesting internal mammary artery through minithoracotomy and anastomosis performed without CPB obviates its potential risks. This procedure is minimally invasive, there is early extubation, shorter intensive care unit (ICU) stay and early hospital discharge [3]. In October, 1995 we started grafting left internal mammary artery (LIMA) on beating heart via a left anterior minithoracotomy. Here, we report 1-year clinical results of patients who underwent this procedure.
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2. Materials and methods
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From October 1995 to February 1997, 116 patients underwent minithoracotomy and direct CABG without CPB. Procedure was completed in 108 cases while in eight patients due to technical reasons minithoracotomy was converted to midsternotomy and LIMA to LAD anastomosis was done on beating heart without CPB in seven cases and in one case LIMA to LAD anastomosis was performed on CPB with cardioplegic arrest. In 108 cases the procedure was completed through minithoracotomy, LIMA to LAD anastomosis was done in 107 cases and in one case LIMA to LAD and right internal mammary artery (RIMA) to right coronary artery (RCA) anastomosis was done through bilateral minithoracotomy. Two patients also underwent left carotid endarterectomy along with LIMA to LAD anastomosis. Preoperative data of these patients are shown in Table 1
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2.1 Surgical indications
Patients who were included in the present series were the following: (1) cases with isolated LAD lesions who were not candidates for PTCA due to proximal or complex stenoses; (2) with LAD lesion and a second vessel (right coronary or circumflex arteries) occluded and recanalized or with a mild stenosis or stenosis that could be dilated by PTCA; (3) LAD disease and disease of two other vessels with a combination of the situations previously described; (4) patients with multiple vessel disease in whom CPB had a presumed high morbidity (renal dysfunction, severe respiratory insufficiency, diffuse cerebrovascular disease, aortic atheroma and old age); (5) redo cases whose LIMA was not used in previous operation and LAD was the only vessel to be bypassed.
2.2 Anesthetic technique
Patients were premedicated with lorazepam and morphine. Anesthesia was induced with diazepam, morphine sulphate, vecuronium bromide and thiopentone sodium and maintained with halothane/isoflurane and nitrous oxide in oxygen. Monitoring included seven lead electrocardiogram (ECG) with ST segment analysis, pulse oximetry, end tidal carbon dioxide estimation, pulmonary artery pressures, cardiac output by thermodilution pulmonary artery catheter, transesophageal echocardiography (TEE) and continuous EEG in patients undergoing carotid endarterectomy. In the first 10 cases, the trachea was intubated with a double lumen endobronchial tube with the aim to facilitate IMA harvesting. It was however observed that ventilating both lungs did not hamper dissection of the IMA. We now ventilate both lungs with the regular endotracheal tube using high frequency positive pressure ventilation with a respiratory rate of 60 breaths per min and tidal volume of about 150 ml during dissection of IMA and during the period of coronary anastomosis. Continuous infusion of nitroglycerine (0.5 µg/kg per min) was used to promote venodilation. Mephenteramine/ephedrine was used to maintain systolic blood pressure between 80 and 100 mmHg. Esmolol infusion was titrated to achieve a heart rate of 60–80/min. Pediatric size internal defibrillator paddles were kept at hand and the facility to go on CPB, kept in readiness. Postoperative pain management with bupivacaine hydrochloride included epidural analgesia in 52 patients, intrapleural analgesia in 47 patients, and intercostal block in four patients; the remaining five patients were managed only with analgesic drugs either orally or parentally. We have compared intrapleural analgesia with thoracic epidural analgesia for MIDCAB procedures and found both to be equally effective. Intrapleural analgesia has the advantage of simplicity and avoidance of risk of epidural hematoma. In our practice intrapleural analgesia is the preferred mode of postoperative pain relief in MIDCAB procedures.
2.3 Surgical technique
The patients were positioned supine. Left anterior thoracotomy was performed through the 4th intercostal space for LIMA dissection (Fig. 1
), while RIMA was dissected through a right anterior thoracotomy in the 5th intercostal space. In the patient who needed bilateral minithoracotomy, left was performed first. In the initial 22 cases, we excised the 4th left costal cartilage to facilitate LIMA harvesting. Subsequently, we found that dislocation of the 4th costo-sternal joint provided better retraction for LIMA dissection. Pleural cavity is opened routinely, ribs are retracted and pericardium is incised vertically (parallel to the sternum). LAD or RCA is inspected for the feasibility of surgery. An intramyocardial, calcified, or small LAD and LAD located beneath the sternum makes the anastomosis very difficult through this route. When any of these occurs, the chest is closed and the sternal approach is used. If LAD is abnormally lateral, inferior epigastric artery or saphenous vein is used to lengthen LIMA. In present series we used inferior epigastric artery once and saphenous vein graft twice to lengthen LIMA to reach laterally placed LAD. Inferior epigastric artery and saphenous vein grafts were anastomosed end to end with LIMA to get extra length. We did LIMA lengthening procedure in our initial experience. Now the length of LIMA does not pose a problem to bypass even laterally placed LAD, as we can dissect the LIMA up to the first rib with the help of CTS mammary retractor.
We always harvest IMA under direct vision. Length of IMA harvested is dependent on the location of target coronary artery. In our experience we have dissected the length of IMAs in the range of 4–8 cm. IMA is harvested skeletonized in the majority of cases to achieve more length. After systemic heparinization (1.5 mg/kg), IMA is divided distally and soft bulldog clamp applied at the tip. LAD or RCA is then occluded proximally and distally using a 3/0 prolene (Ethicon, Somerville, NJ, USA) suture with a 25 mm needle passed twice to surround the vessel. To avoid any direct compression of the suture on the coronary vessel wall, the needle, after the first bite, is passed through a small piece of silicone tubing.
Distal IMA is prepared as usual. The anastomotic site of LAD is dissected. LAD is then incised with a knife (sharp points, 15 degrees) for 4–5 mm. Anastomosis is performed using two 8/0 prolene with a 6 mm needle separately for heal and apex. After completion of anastomosis IMA and coronary artery are unclamped and hemostasis is carefully checked. A drain is positioned in the pleural cavity and if desired a small catheter is also placed in pleural cavity to infuse bupivacaine for postoperative analgesia. The wound is closed as usual.
In two patients we also performed left carotid endarterectomy along with LIMA to LAD anastomosis for symptomatic carotid artery disease. In both these cases carotid endarterectomy was performed first followed by minithoracotomy and LIMA to LAD anastomosis.
Two patients who had lesions in other coronary arteries along with LAD, underwent PTCA to circumflex artery 5 days after minithoracotomy and LIMA to LAD anastomosis.
2.4 Postoperative course
All patients were admitted to ICU where blood samples, chest roentgenograms, and electrocardiograms were obtained. Patients who were still on ventilators were extubated once they showed adequate respiratory effort with satisfactory blood gases. The drain and intrapleural catheter were removed on the morning of the first postoperative day. Doppler flow evaluation of mammary coronary artery anastomosis was done on the 5th postoperative day. In our earlier, cases predischarge angiography was scheduled for each patient on the 5th postoperative day. Recently this examination has been performed only in the presence of a doubtful or negative Doppler flow evaluation, as the sensitivity and specificity of the Doppler flow evaluation were found to be quite high. For postoperative LIMA graft study the origin of LIMA was studied from the left supraclavicular fossa utilizing a 7.5/5.5 MHz phased array transducer probe on a HP Sonos 2500 echocardiography machine. The vertical course of IMA was studied transthoracically using 7.5 MHz linear array probe.
2.5 Follow-up
Patients were followed up at our outpatient clinic at 3 and 6 months postoperatively. All patients were subjected to a stress test and Doppler flow evaluation of mammary coronary anastomosis. In patients who failed to report for postoperative follow-up, questionnaires were sent to know their general condition and functional status.
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3. Results
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The results are summarized in Table 2
. In eight patients the LAD was not found or considered to be too small or too laterally placed hence LIMA was unable to reach at the target site. The chest was closed and all these patients underwent LIMA to LAD grafting via a median sternotomy, with (n=1) or without (n=7) CPB. The remaining 108 patients underwent mammary coronary artery anastomosis without CPB through minithoracotomy. In 107 patients, LIMA to LAD anastomosis was done while in one case LIMA to LAD and RIMA to RCA anastomosis was done through bilateral minithoracotomy. Technical details are shown in Table 2. In two patients who had significant carotid artery disease, left carotid endarterectomy was also done simultaneously along with LIMA to LAD grafting. Both of those patients had uneventful postoperative recovery.
Forty-two patients were extubated in operating room; 66 of the remaining patients were extubated in ICU 2–10 h after surgery. None of the patients required inotropic support.
One patient was re-explored for postoperative bleeding, an intercostal artery from the LIMA was bleeding due to dislodgement of the hemoclip. This was the only patient who required blood transfusion.
There was no incidence of peri-operative myocardial infarction, which was evaluated on the basis of appearance of new Q waves on ECG and an increase in the level of myocardial-specific isoenzyme of creatine kinase. Postoperative Doppler flow study of LIMA to LAD anastomosis was performed in 102 patients before discharge from hospital. In 100 patients diastolic flow was excellent (Fig. 2
) whereas in two patients there was no diastolic flow which was confirmed on angiography (Fig. 3
Fig. 4
). Postoperative angiograms, performed in 53 patients, showed adequate flow at LIMA to LAD junction in 51 patients (Fig. 5
). One patient had narrowing at this site, which was significantly relieved by PTCA. In another patient LIMA was not visualized distally on angiography hence the patient was re-explored through mid line sternotomy and thrombosis of the distal 1 cm of LIMA was found. The whole length of LIMA was then harvested and LIMA to LAD anastomosis was performed on a beating heart without CPB. Both these patients are presently in functional class I.
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Fig. 2. Left side of figure shows Doppler flow signals of an intact RIMA as reference, and right side of figure shows Doppler flow signals after LIMA to LAD anastomosis. Note: diastolic augmentation on right hand side indicating patent anastomosis.
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Fig. 3. Doppler flow study done on the 5th postoperative day. Note: there is no diastolic flow signals indicating blocked LIMA.
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Four patients had superficial chest wound disruption, in two chest wound discharge was culture positive. All of the four cases were managed with wound debridement and secondary suturing. All the patients were asymptomatic at the time of discharge from the hospital. The average postoperative hospital stay was 5 days. There was no early or late mortality in this series. Mean follow-up was 10±1.5 months with a follow-up rate of 97.2% (106 of 108 patients). Ninety-eight patients were in functional class I, and stress test showed no ischemia in any patient, eight patients are in angina class II and are now on medical therapy, six of these patients had pre-operative left ventricular ejection fraction 
30% and the remaining two patients were redo cases with ungraftable vessel in the posterolateral wall. In five of these patients late angiography (5–7 months) was done and in all five cases LIMA to LAD anastomosis was patent.
Two patients underwent complementary PTCA to circumflex artery after minithoracotomy and LIMA to LAD anastomosis and had excellent results with negative stress test for inducible ischemia.
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4. Discussion
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Myocardial revascularization through minimally invasive and video assisted surgical techniques, percutaneous CPB, aortic occlusion and delivery of cardioplegic solution, and total endoscopic myocardial revascularization in the animal model are the most current evolutions in cardiac surgery [1]. Minimally invasive coronary artery bypass grafting is developing rapidly and provides several benefits to the patients. It avoids median sternotomy and CPB, and shortens hospital stay [14, 15, 18]. It contains cost and can be performed in patients at a high risk of complications from conventional CABG. Stroke, derangement of hemostatic mechanism, transfusion of homologous blood and blood products, air embolization, and neurocognitive changes also can be avoided to a large extent [8–10].
Mammary to coronary artery anastomosis in a beating heart via minithoracotomy is a different approach to the surgical treatment of coronary artery disease for different reasons. Surgical invasiveness is minimal and the patients comfort is high; furthermore, postoperative hospital stay is much shorter with this procedure than conventional CABG. This is primarily due to avoidance of CPB and not due to the position or length of the incision. Other authors [17]are using other routes, using femoro femoral bypass and including cold ventricular fibrillation.
LIMA to LAD anastomosis is easier via left anterior minithoracotomy than via a median sternotomy. In fact, the heart in the latter situation rotates with every beat, as the pericardium is opened and the lungs are displaced, via minithoracotomy the heart moves up and down, as the pericardium and lungs remain in place [6]. In redo CABG via minithoracotomy the heart movements are minimal as the adhesions remains intact except in the area of target vessel. The use of two sutures to perform the anastomosis stabilizes the operative field and gives opportunity to suture heel and apex separately while the mammary artery is not brought down over the coronary arteriotomy.
In our experience in 6.8% of the cases we had to convert the minithoracotomy to midline sternotomy due to intramyocardial LAD in four cases, small LAD in one case and extreme laterally placed LAD in three cases. This happened in our initial experience. Now our conversion rate has gone down and in the last 50 cases we have not done any conversion. Coronary angioplasty, with a 33–60% restenosis rate at 6 months [12], remains the most popular coronary revascularization procedure despite more than 10 year patency of LIMA to LAD grafts of 85–90% [13]. This may be because of morbidity of CABG. This minimally invasive surgical technique may become an alternative, although it needs further larger studies to define indications, refine the surgical techniques, and have a long term follow-up [6].
Complementary PTCA along with minimally invasive coronary artery surgery is a good possibility. Two patients in our series underwent PTCA to circumflex arteries 5 days after the minithoracotomy and LIMA to LAD anastomosis. Both of these patients were high risks for CPB, one was a 70-year-old male with diffuse encephalopathy. He had complex LAD lesion not suitable for PTCA and 70% lesion in the circumflex artery. Another patient was a 60-year-old male with severe renal dysfunction. He had triple vessel disease and LAD was not suitable for PTCA. Both of these cases had successful PTCA after LIMA to LAD anastomosis.
Mortality and morbidity rates of reoperative CABG are higher than in primary CABG. Several independent determinants of operative mortality for reoperative CABG have been identified, but the danger of the reoperative CABG is mainly in the reopening of the sternum and in the manipulation of the heart and the old grafts. Therefore, minimally invasive direct CABG operations seems a good technique for re-operative CABG if only the LAD needs to be revascularized and the LIMA has not been used previously [4]. In the present series in five patients who came for redo CABG and LAD was the only vessel to be bypassed due to patent grafts or ungraftable vessels in other areas and had intact LIMA. Left minithoracotomy and LIMA to LAD anastomosis was done successfully. Patients showed improvement in their functional status; three of them are in functional class I and two in functional class II.
The technique described in this report combines minithoracotomy, direct-vision harvesting of IMA, and mammary-coronary artery anastomosis without CPB by a less invasive approach than standard CABG. In the present series the average postoperative hospital stay was 5 days, which is more than in other reported series. We kept the patient in the hospital longer to carry out postoperative Doppler flow studies and angiograms to evaluate the patency of the mammary-coronary artery anastomosis during the learning curve of the procedure. The procedure was found to be safe, simple, and without mortality. There was minimal morbidity in terms of chest wound problems in four patients. Patients had short ICU stays and excellent early and intermediate term results, as demonstrated by Doppler flow study, angiography and functional status.
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5. Conclusion
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Mammary-coronary artery anastomosis via minithoracotomy is a different approach to the treatment of coronary artery disease. This approach can be used to bypass the anterior coronary arteries (LAD, diagonal branch and RCA) on beating heart without CPB. In fact, reduction of postoperative morbidity and consequent shorter postoperative hospital stay are very important end points when cost containment is crucial for health care delivery system. Our one year clinical experience with mammary-coronary artery anastomosis via minithoracotomy allows us to state that this procedure is safe, and reproducible. We believe that this procedure is going to be used more frequently in future as a technique of myocardial revascularization in selected cases, although we recognize that longer follow-up and more experience are needed.
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Acknowledgments
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The authors wish to acknowledge the secretarial assistance given by Mrs. Priti Saxena and Ms. Pooja Arora for preparation of the manuscript.
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Footnotes
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1 Presented at the 1st World Congress on Minimally Invasive Cardiac Surgery, Paris, May 30–31, 1997. 
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References
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- Acuff TL, Landreneau RJ, Griffith BP, Mack MT. Minimally invasive coronary artery bypass grafting. Ann Thorac Surg 1996;61:135-137.[Abstract/Free Full Text]
- Benetti FJ, Naselli G, Wood M, Geffner L. Direct myocardial revascularization without extracorporeal circulation. Experience in 700 patients. Chest 1991;100:312-316.[Abstract/Free Full Text]
- Benetti FJ, Ballester C, Sani G, Boonstra P, Grandjean J. Video assisted coronary bypass surgery. J Card Surg 1995;10:620-625.[Medline]
- Boonstra PW, Grandjean JG, Mariani MA. Re-operative coronary bypass grafting without cardiopulmonary bypass through small thoracotomy. Ann Thorac Surg 1997;63:405-407.[Abstract/Free Full Text]
- Buffolo E, Silva de Andrade JC, Rodrigues Branco JNR, Teles CA, Aguiar LF, Gomes WJ. Coronary artery bypass surgery without cardiopulmonary bypass. Ann Thorac Surg 1996;61:63-66.[Abstract/Free Full Text]
- Calafiore AM, Di Giammarco G, Teodori G, Bosco G, D'Annunzio E, Baarsotti A, Moddestra N, Paloscia L, Vitolla G, Sciarra A, Fino C, Coritini M. Left anterior descending coronary artery grafting via left anterior small thoracotomy without cardiopulmonary bypass. Ann Thorac Surg 1996;61:1658-1665.[Abstract/Free Full Text]
- Fanning WJ, Kakos GS, Williams Jr. TE. Reoperative coronary artery grafting without cardiopulmonary bypass. Ann Thorac Surg 1993;55:486-489.[Abstract]
- Gayes JM, Emery RW, Nissen MD. Anesthetic considerations for patients undergoing minimally invasive coronary artery bypass surgery: mini-sternotomy and mini-thoracotomy approaches. J Cardiothoracic Vasc Anesth 1996;10:531-535.[Medline]
- Hensley FA. Minimally invasive revascularisation surgery. Here to stay?. J Cardiothoracic Vasc Anesth 1996;10:445-446.[Medline]
- Juneja R, Mehta Y, Mishra Y, Trehan N. Minimally invasive coronary artery surgery – anesthetic consideration. J Cardiothorac Vasc Anesth 1997;11(i):123-124.[Medline]
- Kolessov VI. Mammary artery-coronary artery anastomosis as a method of treatment for angina pectoris. J Thoracic Cardiovasc Surg 1967;94:535-544.
- Landan C, Lange RA, Hills LD. Percutaneous transluminal coronary angioplasty. N Engl J Med 1994;330:981-993.[Free Full Text]
- Loop FD, Lytle BW, Cosgrove DM, Stewart RW. Influence of the internal mammary artery graft of 10 year survival and other cardiac events. N Engl J Med 1986;314:1-6.[Abstract]
- Lytle BW. Minimally invasive cardiac surgery. J Thorac Cardiovasc Surg 1996;111:554-555.[Medline]
- Mishra YK, Mehta Y, Juneja R, Kasliwal RR, Mittal S, Trehan N. Mammary coronary artery anastomosis without cardiopulmonary bypass through minithoracotomy. Ann Thorac Surg 1997;63:S114-S118.[Medline]
- Pfister AJ, Zaki MS, Garcia JM, Mispireta LA, Corso PJ, Qazi AG, Boyce SW, Coughlin TR, Gurny P. Coronary artery bypass without cardiopulmonary bypass. Ann Thorac Surg 1992;54:1085-1092.[Abstract]
- Robinson MC, Gross DR, Zeman W, Stedje-Larsen E, et al. Minimally invasive coronary artery bypass grafting: a new method using anterior mediastinotomy. J Card Surg 1995;10:529-536.[Medline]
- Standbridge R, De L, Symons GV, Banwell PE. Minimal access surgery for coronary artery revascularization. Lancet 1995;346:837.[Medline]
- Subramanian VA, Sani G, Benetti FJ, Calafiore AM. Minimally invasive coronary bypass surgery: a multi center report of preliminary clinical experience. Circulation 1995;92(Suppl):1645.
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Abstract
1. Introduction
