Totally endoscopic myocardial revascularization (experimental study).

Background. The purpose of this study is to examine the feasibility of performing totally endoscopic myocardial revascularization through abdominal cavity.

Methods. 46 human cadavers were operated on in order to develop a surgical approach of totally endoscopic myocardial revascularization. A right gastroepiploic artery (RGEA) was harvested endoscopically in all cases through 3 troacars inserted into abdominal cavity. The average length of conduit was 27 ± 2.5 cm. The meantime of harvesting was 45min ± 25 min. Then a hole of 5 cm was made in corpus tendineum of diaphragm to exposure the right coronary artery (RCA). With the help of two vacuum pods inserted in pericardium via 10 mm extra incisions we fixed a site of RCA and made an RGEA-RCA anastomosis using endoscopic instruments. In 20 cases continuous prolene suture was used and in 26 experiments we applied a sutureless technique.

Results. A patency rate was 50% (23 anastomosis were patent).

Conclusions. Despite of comparatively low patency rate, the transabdominal approach of totally endoscopic bypass grafting is promising and demands further investigation.

Minimally invasive surgical concept has gained acceptance in all cardiac surgery subspecialties. Despite of the fact that the first presentations regarding minimally invasive direct coronary artery bypass (MIDCAB) were made just four years ago, excellent results have been obtained with MIDCAB all over the World (1). This field has been developed in several directions: — the most commonly performed minimally invasive procedure is bypass grafting of the left anterior descending artery (LAD) with the use of the left internal mammary artery (LIMA) through a limited thoracotomy (2); — MIDCAB with thoracoscopic support (3,10); — port-access coronary surgery performed on the basis of femorofemoral cardiopulmonary bypass (CPB). In literature there are just a few articles devoted to the first experimental (4) or clinical (5) experience of the totally thoracoscopic coronary bypass grafting with the use of `Heartport` system (Heartport, Inc., Redwood, Calif.) for CPB. Besides its obvious advantages, this approach requires CPB, what may limits the indications for this procedure, particularly in higher risk patients. Meanwhile, experimental studies of the fully thoracoscopic coronary artery bypass grafting on the beating heart have been continued which, in our opinion, corresponds to the MIDCAB concept completely (6,7).

For the most part, MIDCAB procedure is limited by the single-vessel disease, usually that of the LAD, although some experience with bypass of the diagonal, intermediate branches of the left coronary artery and the right coronary artery (RCA) exist (8). In the case of the RCA lesion one of the conduits of choice for MIDCAB surgery is the right gastroepiploic artery (RGEA) (2,9), however, harvesting of this conduit by the traditional technique may be accompanied by certain complications: intestinal paralysis, adhesion process, hernias. An endoscopic approach of the RGEA harvesting leads to solving these problems (11).

The Material and Methods

Since 1997 our team of cardiac surgeons has carried out more than 200 experiments on the application of the endoscopic technique in MIDCAB surgery. Both cadaver and dog experiments were performed in order to develop thoracoscopic and laparoscopic approach for harvesting of the IMAs and the RGEA, to gain manual practice, working with endoscopic instruments and performing coronary anastomosis through limited access on the beating heart. All animals have received humane care in compliance with “Guide for the Care and Use of Laboratory Animals” (NIH publication 85−23, revised 1985). We have subsequently developed technique for the coronary anastomosis on the beating heart, which included heart protection (B-blockers, Ca-channel blockers) and stabilization as well; technique of the thoracoscopic dissection of the LIMA via left-sided ports; technique of the thoracoscopic dissection of the RIMA via right-sided ports; technique of both the LIMA and the RIMA dissection via left-sided ports; technique of the RGEA endoscopic mobilization and taking it into the pericardium and a surgical method for the fully endoscopic RCA bypass grafting with the use of the RGEA.

Human cadavers and mongrel dogs weighting 20 to 25 kg were used to determine a surgical method for laparoscopic dissection of the RGEA. We used 30−degree thoracoscope without magnification and endoscopic instruments, which are usually used for laparoscopic surgery.

Air insufflation into the abdominal cavity was performed through the `Veress` needle and then three 10−mm ports were inserted — for thoracoscope always via annulus umbilicalis.

We studied several ports` positions for the instruments and concluded that their location to the left of thoracoscope (in the left mesogastrium) is the best position. Dissection was begun in the middle portion of the RGEA towards to its proximal and distal ends with endoscopic scissors and forceps. Surgical clips and electrocautery were applied to secure the side branches of the RGEA. In cadaver group sometimes we used an additional port with the `Babcock` forceps to retract the stomach. After complete dissection the artery was cut off in the distal part and positioned via diaphragm into pericardium, with care taken to avoid twisting.

In clinical practice we started with performing the anastomosis between the LAD and the thoracoscopically harvested LIMA through the limited anterior thoracotomy. Endoscopic technique allowed us to gain maximal conduit length, avoid kinking, eliminate any concern regarding side branch `steal` of the LIMA, and performed really minimal access of 4 to 5 cm. Then we began to use endoscopic technique in patients with two-vessel lesions. The surgical method of thoracoscopic harvesting of both the LIMA and the RIMA via left-sided ports with subsequent using of the RIMA as a free graft, anastomosing `end to side` with the LIMA through the anterior thoracotomy was applied in patients with the LAD and the diagonal branch lesions. In patients with the LAD and the RCA atherosclerosis we used the endoscopic harvesting of the LIMA and the RGEA and two limited incisions, consequently, the left anterior thoracotomy and the lower ministernotomy. The employment of the endoscopic technique for the RGEA harvesting, in our opinion has some obvious advantages: — less traumatic then laparotomy or minilaparotomy; — elimination of any concern regarding kinking; — easy control of feasible intraoperative bleeding; — prevention of hernias and adhesion process. Recently, we have successfully applied endoscopic support in a few patients with three-vessel lesions.

Anatomical proximity of the pericardium and the diaphragm gave us the idea of transdiaphragmal approach for endoscopic anastomosis of the RGEA to the RCA and our experimental and clinical experience allowed us to start developing of a totally endoscopic technique of the RCA bypass grafting. Our current experimental studies are devoted to this problem. All experiments were carried on in the operating room, where V.P.Demikhov used to operate in, which was a matter of our great inspiration.

Method.

46 cadavers were used in our current studies. They were divided in two groups — 1 — N=20; 2 — N=26. In the first group the experiments started with harvesting of the RGEA through three 10−mm ports as described above. The incision of 5 cm in corpus tendineum of the diaphragm was made to expose the RCA. Three additional 10−mm ports were inserted into abdominal cavity in the right mesogastrium.

An endoscopic atraumatic temporary occlusion clamp was applied to the RGEA and then the conduit was positioned into the pericardium. The utmost right and the utmost left ports were used for vacuum pods in order to stabilize the target site of the RCA and they also retracted the diaphragm improving the exposure of the RCA. A five to seven millimeter arteriotomy was made and the RGEA was anastomosed with the RCA with a running continuous suture. The surgeon controlled endoscopic instruments: microvascular anastomosis suture needle holder and microvascular forceps, and the assistant guided the endoscope and microvascular forceps. A `U` stitch was placed in the heel of the RGEA, with both needles passing from out to in, to facilitate the anastomosis. The needles were then both passed from within the heel of the RCA to out, before one arm was sewn up each side toward the toe. On completion of the anastomosis, an instrument tie was performed. The temporary occlusion clamps on the RCA applied near the anastomotic site were released. The time of the complete anastomosis was 25 to 40 min.

In the second group, experiments were begun with harvesting of the RGEA and taking it into the pericardium. Then a sutureless technique was applied: a frame construction specially developed for sutureless anastomosis was put on the distal part of the RGEA. Four `U`stitches were placed in the heel, in the toe and in both sides of the RGEA. Pulling all the ligatures the surgeon and the assistant turned the edge inside out on the frame construction and inserted the conduit with the frame construction on into the distal part of the RCA. The time of the performing of the anastomosis was 18 to 25 min. At this stage the experiments were completed.

Results.

The endoscopic technique of the RGEA harvesting allowed the dissection of the whole length from pylorus till splenic arteries breves. The average length of conduit was in human 27+−2.5cm. The length of the artery in the pericardium (8 to 14 cm) was enough to perform anastomosis with the RCA in retrograde or anterograde directions and even with any other coronary artery. The meantime of the harvesting was 45min+−25 min. Even in the first experiments it did not take more than 70 min to harvest the whole length of the RGEA. Neither the RGEA nor the stomach damage to occur. On completion of each experiment we checked the patency of the anastomoses. In the first group fifteen of twentieth anastomoses were patent and were free of narrowing. In the second group only eight anastomoses were normal and patent, nine — were patent but narrowed. The main problem we faced while inserting the RGEA with the frame construction on into the RCA was the deformation of the anastomosis due to some shortcomings of the construction. Thus twenty-three anastomoses (50%) were successful.

Discussion.

At the present stage the method is not well worked out yet. At the very beginning we had to solve the problem of the length of the endoscopic instruments. In order to manipulate in the pericardium through transabdominal approach we had to lengthen the instruments up to 45 cm. Quite a few problems are to be solved. One of them is a closing of the incision in the diaphragm. It is obligatory but not a simple procedure and we have not developed it yet. During the experiment six to eight ports are to be inserted, which causes more intensive insufflation, which in its turn may cause cooling of the patient. In our opinion, using of the alternative to air insufflation — laparolifter is not convenient because of changing the geometry of the abdominal cavity.

The main unsolved problem still is oxygen supply of the myocardium during the cross clamping of the RCA. According to our clinical practice the RCA is the most sensible and unpredictable to oxygen insufficiency of coronary arteries. So one of the possible ways to solve the problem is to shorten the time of the RCA clamping and on the other hand, to fasten the anastomosis performing. Quite a few alternatives to an endoscopically sutured anastomosis have been examined including laser tissue wielding, tissue gluing and vascular staplers, a sutured anastomosis remains to be the most applicable (7). However, appearance of the new coronary anastomosis staplers for endoscopic coronary surgery, similar to those anastomosis staplers for conventional coronary surgery which are already exist, may cause a great progress of endoscopic myocardial revascularization.

Our experimental studies demonstrate that the performance of totally endoscopic coronary bypass grafting through abdominal cavity is principally possible.

Conclusion.

Our efforts are devoted toward extending the MIDCAB surgery and making it even less invasive. According to our experience, the most limiting factors for fully endoscopic coronary surgery are: — the lack of the surgeon’s experience in performing an exact arterial conduit-coronary artery anastomosis with endoscopic instruments on the beating heart; — the lack of the specially made endoscopic instruments. We hope that as surgeons gain more experience and enabling technologies simplify the technique, the procedure can be extended.

Despite comparatively low patency rate the transabdominal approach of totally endoscopic bypass grafting is promising and may be a great contribute to promoting the strategy of the fully endoscopic coronary surgery on the beating heart.

References:

1. Benetti FJ Ballester C, Sani G, et al. Videoassisted coronary bypass surgery. // J Cardiac Surg 1995; 10: 620−5.

2. Subramanian V., McCabe J.C., Geller C.M. Minimally invasive direct coronary artery bypass grafting: two-year clinical experience. // Ann Thorac Surg 1997; 64: 1648−55

3. Nataf P., Lima L., Vaissier E., et al. Video-assisted coronary artery surgery: Clinical Experience. // J. Cardivasc. Surg., 1996, 4 (Suppl. 1), Abstracts, p 14

4. Gilles Soulez, Michel Gagner, Eric Therasse et al. Catheter-Assisted Totally Thoracoscopic Coronary Artery Bypass Grafting: A Feasibility Study // (Ann Thorac Surg 1997; 64: 1036−40

5. 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: 567−73

6. Mack M. Minimally invasive thoracoscopically assisted coronary artery bypass surgery. In: 10−th Annual Meeting the European association for cardiothoracic surgery. Prague, 1996, N 21, p 112.

7. Jansen E.W.L. Towards minimally invasive coronary artery bypass grafting. 1998, Brouwer Uithof, Utrecht.

8. Calafiore A. M., Angelini G.D., Bergsland J. et al. Minimally invasive coronary artery bypass grafting. // Ann Thorac Surg 1996; 62: 1545−8.

9. Grandjean JG, Mariani MA, Ebels T. Coronary reoperation via small laparotomy using right gastroepiploic artery without CPB. // Ann of Thorac Surg 1996; 61: 1853−5.

10. Mack M.J., Acuff T.E., Casimir-Ahn H. et al. Video-assisted coronary bypass grafting on the beating heart. // Ann Thorac Surg 1997; 63: S 100−3

11. Vlassov G.P., Deyneka K.S., Travine N.O. et al. Perviy opit maloinvasivnoy revaskulyarizacii myocarda s endoscopicheskoy podderzhkoy. // Grudnaya i serdechno-sosudistaya chirurgia, 1998, N3, p.4−7

 

 

Биорастворимый коронарный стент - новая техника лечения стенокардии

Сердечно сосудистые заболевания. Лечение сердечно-сосудистых заболеваний