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Ann Thorac Surg 2000;70:1066-1069
© 2000 The Society of Thoracic Surgeons

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Supplement: cardiothoracic techniques & technologies

Angiographic evaluation of graft patency in minimally invasive direct coronary artery bypass grafting

^a Heart Institute (In Cor), Brazil

Address reprint requests to Dr Jatene, Divisão Cirúrgica, Cerqueira César, Av Dr Enéas de Carvalho Aguiar, 44, São Paulo—SP, CEP 05403-000 Brazil
e-mail: fabiojatene{at}incor.usp.br

Presented at the Sixth Annual Cardiothoracic Techniques and Technologies Meeting 2000, Ft Lauderdale, FL, Jan 27–29, 2000.

	Abstract

Top Abstract Introduction Patients and methods Results Comment References

 
Background. The objective of this report is to describe our experience using minimally invasive direct coronary artery bypass grafting and to evaluate angiographic patency of anastomoses.

Methods. A total of 120 patients (86 men) were operated on, with ages ranging from 30 to 83 years (mean = 61.2 years). Two access routes were used: for single left anterior descending coronary artery lesions an 8 cm anterior minithoracotomy was performed at the fourth left intercostal space. Extracorporeal circulation was not used. In the last 82 patients a restraining device was used for the regional reduction of heart beats. Coronary cineangiography was carried out between postoperative days 1 and 3 in 84 (70%) patients. Anastomoses were graded: grade A, no blocks; grade B, blocks of more than 50%; grade C, occlusion. This evaluation was performed for two different periods: in the first period a restraining device was not used and in the second period a restraining device was used.

Results. In the first study period (38 anastomoses) coronary cineangiography showed grade A, 79%, grade B, 5.2%, and grade C, 15.8%. In the second study period (62 anastomoses), angiography showed grade A, 90.4%, grade B, 6.4%, and grade C, 3.2%. Early mortality was 1.6%.

Conclusions. Minimally invasive coronary artery bypass grafting is a good alternative for some groups of patients. Anastomotic results seem to be better when a restraining device is used.

	Introduction

Top Abstract Introduction Patients and methods Results Comment References

 
Coronary artery bypass grafting is a well-established therapy in the treatment of coronary insufficiency, especially with the use of the left internal mammary artery (LIMA). Grafting has shown excellent functional results, and remains patent in the long-term, especially when LIMA is used in the left anterior descending (LAD) coronary artery. Nevertheless, transluminal percutaneous angioplasty has been the choice for the treatment of these lesions, although comparative studies of these techniques show a lower complication rate, such as symptomatology recurrence and need for new operations.

To combine the greater benefits of the conventional coronary artery bypass graft, especially anastomosis between LIMA and LAD, with several of the angioplasty benefits, some groups have used the minimally invasive coronary artery bypass graft. The so-called minimally invasive surgery has been progressively more accepted in the several surgical specialties, including thoracic procedures [1]. The procedures have changed in the last few years, especially with regard to the access route and surgical techniques. Initially, the procedure by small left thoracotomy without extracorporeal circulation (ECC), to treat one or two arteries, was an interesting choice and a significant technological improvement. However, it was gradually replaced by techniques using partial or total sternotomy, without ECC, using a restraining device that may treat several coronary arteries.

The objective of this study was to report our experience with this approach and some of our observations, especially the analysis of the angiographic patency of the anastomoses performed.

	Patients and methods

Top Abstract Introduction Patients and methods Results Comment References

 
Of the 120 operated patients 86 (71.6%) were men and 34 (28.4%) were women. Ages ranged from 30 to 83 years (mean 61.2 years).

The patients showed unilateral or bilateral artery lesions greater than 80% of the coronary lumen; 98 (81.6%) patients had unilateral lesions and 22 (18.4%) had bilateral lesions. Of those with unilateral artery lesions, 79.2% were LAD lesions, 1.6% were diagonal artery (Dg) lesions and 0.8% right coronary artery (RCA) lesions. Those with bilateral artery lesions had 17.6% of LAD and Dg lesions and 0.8% of LAD and obtusal marginal circumflex artery (OMg) lesions. Ninety-eight patients (81.6%) received one graft, of which 95 (79.2%) were from the LIMA to the RCA, 2 (1.6%) were from the LIMA to the Dg, and 1 (0.8%) was from the right internal mammary artery (RIMA) to the RCA. In 22 patients (18.4%) two grafts were performed, using LIMA in an artificial Y combined with the saphenous vein or with the radial artery. Twenty-one (17.6%) of these cases were for the LAD/Dg, of which 12 (10%) grafts were LIMA with the saphenous veins and for 9 (7.6%) anastomosis was carried out in Y with the radial artery. In 1 (0.8%) patient LAD/OMg anastomosis and the artificial Y with saphenous vein segment were carried out (Table 1). In 12 (10.0%) patients LIMA was elongated with a segment of the saphenous veins or the radial or epigastric artery. One hundred forty-four anastomoses were carried out in the 120 patients.

In the remaining 24 (20%) cases, 2 (1.6%) of the patients had unilateral artery lesions and 22 (18.4%) bilateral artery lesions and limited median sternotomy was used, with the incisions ranging from 10 to 12 cm and removal of up to 6 cm of the sternal borders (Table 2).

For anterior or parasternal minithoracotomy, the patient was placed in the lateral decubitus position with 30-degree rotation. In only one case, the operation was carried out on in the right side (RIMA to RCA), and in the other cases on the left side. The usual anesthesia technique with orotracheal intubation and double-lumen catheter was used, aiming at allowing unilateral lung collapse and facilitating IMA dissection and exhibition by minithoracotomy.

Left anterior minithoracotomy of 8 to 10 cm was carried out at the fourth intercostal space. The instruments required for LIMA dissection were placed through this incision. Video-assisted thoracoscopy was used for complete LIMA dissection. The branches were ligated with clips and the smaller branches were cauterized. Once dissected, LIMA was clipped caudally after the administration of 1.5 mg/kg heparin. The pericardium was opened longitudinally and repaired to facilitate the exposure of the artery to be revascularized.

In left or right parasternal minithoracotomy, a parasternal incision of approximately 8 to 10 cm is performed with resection of two to three costochondral cartilage and the retractor is placed allowing optimal exposure of the surgical field. With this technique, a smaller LIMA dissection was carried out with partial branch ligature.

In limited median sternotomy the patients were maintained in horizontal decubitus dorsalis and were intubated with a simple orotracheal cannula, with a 10- to 12-cm incision, starting 5 cm below the sternal furcula. A complete sternal longitudinal section was performed and the bone trabeculae were separated for up to 6 cm. This exposure was enough to allow the dissection and ligature of all LIMA branches. Heparin was administered prior to caudal LIMA ligature.

In the three types of approach ECC was not used and the aorta was not manipulated or approached.

Intravenous nitroglycerin was used during the procedure in addition to CO₂ to keep the surgical field bloodless. Heparin was used at the dose of 1.5 mg/kg, and the activated coagulation time was maintained above 250 seconds. Proximal and distal tourniquets were used in the coronary artery.

In the last 82 patients, a restraining device manufactured in the institution’s bioengineering department or a CTS restraining device (CardioThoracic Systems, Inc, Cupertino, CA), whose stabilization principle was local compression, was used.

Anastomosis with continuous suture was performed with one or two 7-0 polypropylene threads. The surgical material used in conventional myocardial revascularization operations was used in this study.

Coronary cineangiography was carried out between the first and third postoperative days in 84 (70%) of the patients, whose evaluation was based on the following findings, according to anastomosis: grade A, no obstructions; grade B, obstruction of more than 50%; grade C, occlusion. This evaluation was carried out in two different periods: in the first period (January 1996 to January 1997) without the restraining device and in the second period (February 1997 to August 1999) with the restraining device.

Fisher’s exact test was used to compare anastomosis impairment in the first and second study periods.

	Results

Top Abstract Introduction Patients and methods Results Comment References

 
One hundred nineteen (99.2%) patients had a good postoperative course, with no electrocardiographic or enzymatic alterations that may have characterized perioperative infarct. One patient (0.8%) showed postoperative enzymatic increase; however, the coronary cineangiography did not show any lesions.

Coronary cineangiography was carried out between the first and third postoperative day in 84 (70%) patients (36 in the first study period and 48 in the second study period). In the first study period with 36 patients and 38 anastomoses, 30 (79%) of the 38 anastomoses were classified as grade A, 2 (5.2%) as grade B, and 6 (15.8%) as grade C. In the second study period, using a restraining device for 48 patients and 62 anastomoses, 56 (90.4%) of the 62 anastomoses were grade A, 4 (6.4%) were grade B, and 2 (3.2%) were grade C (Fig 1).

View larger version (20K): [in this window] [in a new window]   Fig 1. Angiographic evaluation with and without the restraining device.

Patients with Grade B lesions were maintained under clinical treatment. In 5 (4.0%) patients wound healing was delayed due to secretion from the subcutaneous cellular tissue. In 4 (3.2%) patients subcutaneous emphysema developed at the incision site in the early postoperative period that was reabsorbed spontaneously after 72 hours; in 4 (3.2%) patients there was atelectasia, in 3 (2.4%) there was bleeding (the patients were reoperated to review hemostasis), and in 3 (2.4%) there was bronchopneumonia.

Early mortality was 1.6%, due to bronchopneumonia combined with stroke in 1 (0.8%) case and sepsis in 1 (0.8%). Overall mortality was 14.2%.

One hundred eighteen (98.4%) patients were discharged. Of these patients, 115 (95.8%) were discharged after 2 to 9 days (mean 4.6 ± 1.8 days) and 3 (2.4%) patients had extended hospitalization time due to pulmonary infectious process.

	Comment

Top Abstract Introduction Patients and methods Results Comment References

 
The use of LIMA in LAD revascularization is a well-established technique and when compared with medium- and long-term results, it results in less adverse events when compared with medical therapy and balloon angioplasty both in terms of symptoms, requirement of new procedures or related mortality [2].

Several researchers have reported perviousness of 94% to 97% after coronary artery bypass grafting by the conventional technique, up to 30 postoperative days. Other researchers studied graft patency in a period ranging from 1 month to 1 year and observed perviousness ranging from 88% to 93% [3–5].

In our study, 100 anastomoses of the 144 performed were evaluated. This represented 70 (84%) patients undergoing coronary angiography 24 to 96 hours after myocardial revascularization. A perviousness of 92% was obtained. In the first period of January 1996 to January 1997 36 patients received coronary artery bypass grafts and 38 anastomoses were studied without a restraining device and a perviousness of 84.2% was obtained. In the second period, from February 1997 to August 1999, 48 patients received coronary artery bypass grafts and 62 anastomoses were studied with a restraining device and a perviousness of 96.8% was obtained.

These data are similar to those obtained in literature in a series of some studies carried out to evaluate perviousness of anastomoses between IMA and the coronary artery by minimally invasive technique. Calafiore and coworkers [6] evaluated 271 patients in a period of less than a year and obtained patency of 93.7%. Subramanian and coworkers [7] obtained patency of 92% in 169 patients evaluated within 36 postoperative hours. Finally, Mack and coworkers [1] studied 100 patients intraoperatively (up to 96 hours) and obtained a perviousness of 99%.

Several techniques have been used to improve the results of minimally invasive coronary artery bypass grafting, trying to decrease myocardial rate and contractile power, as well as drugs inducing intermittent stop periods of the heart [8]. However, the consensus is that mechanical devices, the so-called restraining devices, improved the results. It is more comfortable to perform anastomosis with a partially immobilized heart, especially at the suture site [1, 6].

We have been using restraining devices since February 1997. Angiographic studies have shown a smaller number of anastomosis lesions when these devices are used.

Different techniques were used throughout this study and three types of minimally invasive surgery access were used: left anterior thoracotomy at the fourth intercostal space, parasternal thoracotomy, and median sternotomy with total sternal section. As we gained experience, it was established that for patients with unilateral lesions left anterior minithoracotomy was the choice procedure and for those with bilateral lesion, limited median thoracotomy was the choice procedure. In the latter group, the left radial artery was used with anastomosis in artificial Y with the IMA to avoid aorta manipulation.

In conclusion, minimally invasive coronary artery bypass grafting has proved to be a new alternative for patients with coronary failure. It enables a better esthetic result, lower cost, and faster recovery. Angiographic results for anastomosis showed a trend to greater patency when a restraining device was used.

	References

Top Abstract Introduction Patients and methods Results Comment References

 

1. Mack M.J., Osborne J.A., Shennib H. Arterial graft patency in coronary artery bypass grafting. Ann Thorac Surg 1998;66:1055-1059.[Abstract/Free Full Text]
2. Hueb W.A., Bellotti G., Oliveira S.A., et al. The Medicine, Angioplasty or Surgery Study (MASS). J Am Coll Cardiol 1995;26:1600-1605.[Abstract]
3. Tyras D.H., Barner H.B., Kaiser G.C., Codd J.E., Pennington D.G., Willman V.L. Bypass grafts to the left anterior descending coronary artery. J Thorac Cardiovasc Surg 1980;80:327-333.[Abstract]
4. Ivert T., Huttunen K., Landou C., Björk V.O. Angiographic studies of internal mammary artery grafts 11 years after coronary artery bypass grafting. J Thorac Cardiovasc Surg 1988;96:1-12.[Abstract]
5. Fitzgibbon G.M., Kafka H.P., Leach A.J., Keon W.J., Hooper G.D., Burton J.R. Coronary bypass graft fate and patient outcome. J Am Coll Cardiol 1996;28:616-626.[Abstract]
6. Calafiore A.M., Di Giammarco G., Teodori G., et al. Midterm results after minimally invasive coronary surgery. J Thorac Cardiovasc Surg 1998;115:763-771.[Abstract/Free Full Text]
7. Subramanian V.A., Sani G., Benetti F.J., Calafiore A.M. Minimally invasive coronary bypass surgery. Circulation 1995;92(Suppl 1):645.
8. Jatene F.B., Pêgo-Fernandes P.M., Hayata A.L., et al. VATS for complete dissection of LIMA in minimally invasive coronary artery bypass grafting. Ann Thorac Surg 1997;63(Suppl 6):S110-S113.

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