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Ann Thorac Surg 2000;70:74-78
© 2000 The Society of Thoracic Surgeons

Original articles: Cardiovascular

The LAST operation is safe and effective: MIDCABG clinical and angiographic evaluation

Alberto Repossini, MDa, Stefano Moriggia, MDa, Vincenzo Cianci, MDa, Oberdan Parodi, MDa, Paolo Sganzerla, MDa, Giorgio Baldrighi, MDa, Franco Bortone, MDa, Vincenzo Arena, MDa

a Cardiovascular Department, Cliniche Gavazzeni, Bergamo, Italy

Address reprint requests to Dr Repossini, Dipartimento Cardiovascolare, Cliniche Gavazzeni, Via Gavazzeni 21, 24100 Bergamo, Italy
e-mail: arepossini{at}clinichegavazzeni.bg.it


   Abstract
Top
 Abstract
Introduction
 Material and methods
 Results
 Comment
 References
 
Background. The aim of this study was to prospectively evaluate the angiographic results of a cohort of consecutive patients who underwent minimally invasive coronary artery revascularization.

Methods. From May 1997 to December 1998, 150 consecutive patients underwent left internal mammary artery to left anterior descending artery anastomosis through a left minithoracotomy on a beating heart in the Cardiovascular Department of Cliniche Gavazzeni, Bergamo, Italy. The mean age was 61.6 years (range, 36 to 84 years); 121 patients (81%) were men. Isolated left anterior descending artery disease was present in 74 patients.

Results. In-hospital patency was observed in 100% of the 149 angiographically controlled patients with no anomalies in 99.3% of the anastomoses. Anastomosis was performed on a diseased tract of the target vessel in 3 patients and a stenosis of the target vessel beyond the anastomosis was documented in 3 patients. In one case early angiographic control was not performed due to death of the patient on the 1st postoperative day. The morbidity included postoperative bleeding that required reopening (3.3%) and intraoperative myocardial infarction (2%).

Conclusions. A left internal mammary artery to left anterior descending artery anastomosis on a beating heart through a left minithoracotomy is an alternative approach to myocardial revascularization. Surgical invasiveness is limited, cardiopulmonary bypass risks are avoided, and the procedure is safe and effective. In our consecutive series, postoperative angiographic controls demonstrated graft patency in all patients and very high quality anastomoses. Midterm clinical follow-up (14 months) appears favorable.


   Introduction
Top
 Abstract
 Introduction
Material and methods
 Results
 Comment
 References
 
In the last 3 years, minimally invasive coronary artery bypass graft operation has become an accepted surgical technique. Left anterior descending coronary artery (LAD) grafting using the left internal mammary artery (LIMA) through a left anterior small thoracotomy (LAST) became popular starting in 1994, when Benetti and Ballester [1] revisited this approach after the pioneering work of Kolessov [2]. At first the operation was performed without any stabilizing device and the results were not very good, causing most surgeons and cardiologists to consider LAST really "the last operation to be proposed to their patients."

The recent introduction of stabilizers and instruments to help in LIMA harvesting improved results and the operation became widely accepted as minimally invasive direct coronary artery bypass grafting (MIDCABG). However, only postoperative routine angiographic control in a large consecutive series can confirm the effectiveness of the technique, showing quality of grafts and anastomosis comparable with standard operations. The present study reports our results obtained with this technique in 150 consecutive patients undergoing LAD revascularization.


   Material and methods
Top
 Abstract
 Introduction
 Material and methods
Results
 Comment
 References
 
In the Cardiovascular Department of Cliniche Gavazzeni, Bergamo, Italy, from May 1997 to December 1998, 150 consecutive patients underwent LIMA to LAD anastomosis through a left minithoracotomy (MIDCABG) on a beating heart. No patient receiving only LIMA–LAD was operated on using full sternotomy (with or without cardiopulmonary bypass). In 4 patients (not included in our series) the operation was converted to median sternotomy for different reasons.

Candidates were patients with isolated LAD disease (class M—monovessel) in whom a percutaneous transluminal coronary angioplasty (PTCA) was not advisable (type B and C lesions) or not possible (occluded LAD), patients with LAD disease and a second vessel with a stenosis that should not be treated anyway for irreversible damage, distal hypoplasia (class BM—bivascular, functionally mono), patients with LAD disease and a second vessel disease that could be treated by PTCA after surgical treatment and evaluation of residual ischemia (class B—bivascular), and patients with multiple vessel disease in whom cardiopulmonary bypass (CPB) had a presumed high morbidity (cancer, severe renal failure, diffuse cerebrovascular disease) and MIDCABG was performed as a palliative procedure (class T—triple vessel). Preoperative data are shown in Table 1.


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  		Table 1. Main Preoperative Data

 
The chest was opened through an anterior left minithoracotomy in the fourth intercostal space. The LIMA was harvested skeletonized from the fifth rib to the first intercostal space with the Thoralift (U.S. Surgical Corporation, Norwalk, CT). The pericardium was incised horizontally (parallel to the intercostal space) and the LAD was explored. If the LAD was lateral or the lung approach was particularly invasive, the operator harvested the LIMA to the fifth intercostal space, disarticulating the cartilage of the fifth rib or to the sixth rib by a fifth intercostal space approach. After systemic heparinization (100 IU/kg) the LIMA was clipped distally. At the beginning of our experience, the LAD quality and LIMA length evaluations were performed after the LIMA was harvested for a short length and the LIMA was interrupted at that moment. More recently we have harvested the whole length of the LIMA without interrupting the artery. The LAD was then occluded proximally and distally using a 4-0 polypropylene suture passed once around the vessel and through a small piece of silicone tubing to avoid any direct compression of the suture on the coronary wall. An 8-minute preconditioning was performed. If hemodynamic changes, major arrhythmias, or significant ST-T changes did not occur within this period, the LAD was incised after 1-minute reperfusion. Otherwise, further preconditioning was performed until a period of about 10 minutes free from alterations was achieved. The anastomosis was performed with a single 8-0 or 7-0 polypropylene running suture. Local immobilization of the myocardial surface was achieved using the CTS (CardioThoracicSystem Inc, Cupertino, CA) stabilization device. All patients were admitted to the intensive care unit (ICU). LIMA angiographic control was performed in all patients on the 3rd postoperative day. In a few selected cases (difficult anastomosis, postoperative electrocardiographic changes), angiography was performed at the end of the surgical procedure. These precautions were taken to avoid early ICU readmissions for complications and to evaluate the incidence of complications and the efficacy of the procedure.


   Results
Top
 Abstract
 Introduction
 Material and methods
 Results
Comment
 References
 
Surgical and postoperative results
We performed 150 LIMA–LAD anastomoses on beating hearts without CPB through a left minithoracotomy.

Of the 58 patients with two-vessel disease, 38 were true bivascular patients (B), and 16 (42.1%) received an additional PTCA of the other coronary artery (hybrid procedure) during the same hospital stay. We decided to treat only severe stenosis on anatomically relevant second coronary artery. In case of subcritical stenosis or small branches, PTCA was performed only after scintigraphic evidence of residual ischemia.

In 39 patients (26%) the ejection fraction was lower than 0.35, nevertheless, their perioperative course was uneventful.

After an initial learning period the total time to perform the procedure was reduced from a mean time of 128 minutes to 91 minutes. LAD occlusion time was relatively constant with a mean of 17.5 minutes (range, 8 to 23 minutes).

Intraoperative hemodynamics were without major changes in all patients but 2 (1.3%) who required intravenous infusion of dobutamine for ventricular output decrease and elevation of pulmonary artery pressure. No conversion to CBP was necessary due to hemodynamic impairment. No ventricular fibrillation occurred. A direct anastomosis of LIMA to LAD was obtained in all cases and no LIMA elongation was required.

Four conversions to sternotomy and CBP were necessary (patients not included in this series); causes were not visible LAD in 2 patients, calcified LAD in 1 patient, and too lateral LAD with distal stenosis in 1 patient. The postoperative course was uneventful in all these patients. One patient died the 1st postoperative day after sudden cardiac arrest unresponsive to resuscitation techniques. An emergency CPB was started and surgical revision revealed LIMA avulsion: a saphenous bypass was performed and a centrifugal pump was employed as left ventricular assist device; nevertheless, the patient died due to irreversible cardiogenic shock. Postoperative acute myocardial infarction (AMI) occurred in 3 patients: in 1 patient a thromboendarterectomy (TEA) of the LAD had to be performed due to massive calcifications and postoperative angiography showed reduced LAD runoff. In another patient the procedure was performed as a redo operation and postoperative angiography revealed distal occlusion of the apical portion of the LAD due to embolization from the occluded saphenous graft during manipulation in LIMA harvesting. In the third patient the AMI diagnosis was referred to as CK-MB elevation in the absence of hemodynamic and wall motion alterations. In all 3 patients the anastomoses were patent with no anomalies. In 4 patients the LAD was intramyocardial; in 3 patients careful dissection of myocardial tissue was performed under stabilization and LAD was found; in 1 patient a diagonal branch was bypassed erroneously and after angiographic control the patient was reoperated on through sternotomy and CPB.

Four patients had to be operated on for bleeding at the beginning of our experience. In all 4 patients the bleeding was caused by collateral branches of the mammary satellite veins. Early redo was necessary in 1 patient in whom a diagonal branch was bypassed erroneously. The LIMA was found deeply intramyocardial under the diagonal branch (CBP and sternotomy).

Average bleeding was 255 ± 65 mL; mean orotracheal intubation time was 13 ± 5 hours and mean ICU stay was 1.23 ± 0.4 days. Although surgical access is minimally invasive, it is not painless. Regarding pain treatment on the 1st and 2nd postoperative days, patients were treated with 20 cc intrapleural bupivacaine 0.5% given every 6 hours through a catheter inserted intraoperatively and/or 1.25 mg/kg tramadol administered intravenously every 6 hours. Postoperative data are shown in Table 2.


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  		Table 2. Postoperative Data

 
Quality control of the anastomoses
In-hospital angiographic control was performed in all patients. In all 149 patients LIMA, anastomosis, and the target vessel were patent, with no anomalies in 138, therefore an overall LIMA–LAD patency of 100% was observed. Anastomoses were reviewed and graded in three groups as described by FitzGibbon and colleagues [3]: grade A (excellent graft with unimpaired runoff); grade B (stenosis < 50%); grade O (occluded). Grade A anastomosis was found in 148/149 (99.3%) patients and grade B anastomosis was found in 1 (0.7%) patient. In 5 patients a sharp angulation of the LIMA in the distal part before the anastomosis was observed, with hemodynamic significance (stenosis 50%) in only 1 patient. In 3 patients the anastomosis was performed on a diseased tract of the LAD and in 3 patients the target vessel had a distal stenosis. All these 6 patients had complete LAD occlusion at preoperative angiography with retrograde incomplete visualization from the right coronary artery. No further procedures were performed in these patients as exercise stress test was negative shortly before discharge. Early angiographic results are shown in Table 3.


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  		Table 3. Early Angiographic Results

 
In the 11 patients in whom anomalies were found, a further angiographic control was performed 3 months after operation. All LIMA anomalies disappeared or were strongly reduced; in particular, the 4 patients with LIMA stenosis less than 50% showed a complete normalization of the lumen, whereas in the patient with 60% stenosis a residual 20% stenosis was found.

Follow-up data
After a mean follow-up of 14.4 ± 5 months (range, 7 to 25 months), 147 patients are alive and asymptomatic, without need of redo or PTCA. No patients had AMI.

One patient died after 36 days due to extracardiac causes (cerebrovascular) and 1 patient died after 64 days due to cardiac failure; the latter was a three-vessel patient with depressed (0.26) ejection fraction and severe chronic obstructive pulmonary disease (COPD).

Actuarial survival at 25 months was 98% (Fig 1).



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  		Fig 1. Follow-up at 14.4 ± 5 months (range, 7 to 25 months). Actuarial survival at 25 months was 98%.

 

   Comment
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
References
 
A minimally invasive coronary bypass surgical program was started at our center in May 1997, after a period of training in Chieti Hospital (Dr Calafiore) and in the "stabilization era" [4].

As LIMA patency is the most important determinant of survival and event-free survival after coronary revascularization [5], LAD stabilization allowed us to reproduce the conditions of the arrested heart in terms of anastomosis quality. As postoperative angiography is the gold standard in graft patency assessment, we planned to perform LIMA catheterization in all patients postoperatively. The left humeral or radial percutaneous approach provided a fast and less invasive procedure, and was well accepted and tolerated by all patients.

From the beginning, we considered MIDCABG revascularization a challenging technique that required more technical skills, especially in LIMA harvesting, which is the most critical part of the procedure as well as anastomotic site preparation and stabilization.

A great improvement in LIMA harvesting was achieved with the use of the Thoralift, which in our hands allowed optimal rib retraction providing enough space for harvesting LIMA under direct vision to the first intercostal space; no thoracoscopy was necessary.

In our opinion harvesting should be done proximally as far as possible to achieve maximum LIMA length and mobilization. In our center the harvesting technique of choice is LIMA skeletonization with hemoclips, so we performed this procedure in every case of MIDCABG and found it very effective in terms of LIMA length and harvesting bed hemostasis. Additional LIMA length was provided, when necessary, by further fifth intercostal space approach.

We agree with Calafiore and colleagues [6] that the side branches of the LIMA can be left intact during a partial dissection without causing a steal syndrome as long as the anastomosis to the LAD is accurate, but we also believe that the LIMA must be completely dissected to reach the LAD with a wide curve and no tension, especially in patients with COPD and a lateral LAD (far from the hemisternal line). In our experience the LAD was not accessible for a MIDCABG in 4 patients (excluded from these series). An intramyocardial running LAD was found in 6 patients, and in 3 we succeeded in performing the operation with the LAST operation, even with enhanced difficulties; however, we do not recommend the operation in these cases. Moreover, when the LAD is too far away from the hemisternal line or is diffusely calcified, a more liberal policy for early conversion to sternotomy is recommended to avoid the risk of graft failure. In 3 patients (2%) a partial TEA was performed on the LAD in the presence of diffuse calcification in the anastomotic site. In 1 patient postoperative angiography showed a type A anastomosis with reduced LAD runoff, but the patient had acute myocardial infarction, without hemodynamic complications.

In 1 patient during LIMA harvesting we experienced acute anterior myocardial infarction (possibly due to graft embolization) with patent type A LIMA–LAD anastomosis and distal occlusion of the apical portion of LAD at control angiography. Temporary occlusion of the LAD for the time necessary to perform the anastomosis has no adverse effect in patients with stenosis greater than 80% and we believe, as previously described [7], that the less stenosis of the LAD, the greater the risk of intraoperative ischemia to be expected.

Although the physiologic benefit of ischemic preconditioning is not confirmed [8], we prefer this technique (8-minute occlusion + 1-minute reperfusion) and we employed it in all cases. Most likely the preconditioning occlusion time is too short [9], nevertheless it is a good test for toleration of ischemia before opening the coronary. We never experienced ventricular fibrillation or hemodynamic deterioration leading to emergency CPB. The surface stabilization provided by the CTS instrument was easy and effective in most of the procedures. For intraoperative quality control of the graft, Doppler flow measurement is recommended [9], but it is not available in our institution. Moreover, we believe that neither the quantitative flow measurement nor the more qualitative flow pattern reflects the true quality of the anastomosis [10], therefore, every patient underwent postoperative angiographic control. Results were surprisingly positive and we report a 100% graft patency rate. We experienced some problems in LIMA harvesting or positioning (all at the beginning of our experience) in 5 patients (3.3%) with sharp angulation (kinking) which disappeared or was markedly reduced at 3 month angiography. The intraoperative and postoperative courses were uneventful in most of the patients. Postoperative ventilation and ICU length of stay were standard, comparable with CPB operations. We did not follow any accelerated ICU protocol in order to carefully monitor the postoperative incidence of possible complications (ischemia, bleeding, respiratory distress). As the most critical complications are silent postoperative ischemia and ventricular fibrillation, we consider a 24-hour ICU stay mandatory in any kind of myocardial revascularization, unrelated to technical proceedings (CPB, MIDCABG, off-pump, or PTCA). Fast extubation is not considered an important factor in the early postoperative course and does not influence ICU length of stay.

Coughing and hyperinspiration may cause excessive tension of the LIMA and its consequent avulsion, as observed in the one fatal case. Moreover, this patient had a "lateral LAD," ie, far from the hemisternal line, requiring "per se" additional LIMA length.

In patients with severe COPD, MIDCABG operation may be dangerous and the only way to minimize risks is to harvest the LIMA as proximally as possible to allow its full length to lay under the lung. If complete LIMA harvesting is not possible, we suggest conversion to sternotomy.

In conclusion, MIDCABG without CPB is safe and effective in routine revascularization of the LAD. Using appropriate stabilization devices for LIMA harvesting and LAD stabilization, the technique is now standardized. The perioperative course is usually uneventful with early recovery and no complications.

In our consecutive series, postoperative angiographic controls demonstrated a graft patency in all patients and a very high quality of anastomosis. Midterm clinical follow-up (14 months) appears favorable while the angiographic control is running.


   References
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
 References
 

  1. Benetti F.J., Ballester C. Use of thoracoscopy and a minimal thoracotomy, in mammary-coronary bypass to left anterior descending artery, without extracorporeal circulation. Experience in 2 cases. J Cardiovasc Surg (Torino) 1995;36:159-161.[Medline]
  2. Kolessov V.I. Mammary artery-coronary artery anastomosis as method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967;54:535-544.[Medline]
  3. FitzGibbon G.M., Burton J.R., Leach A.J. Coronary bypass graft fate. Angiographic grading of 1,400 consecutive grafts early after operation and of 1,132 after one year. Circulation 1978;57:1070-1074.[Abstract/Free Full Text]
  4. Calafiore A.M., Vitolla G., Mazzei V., et al. The LAST operation. Ann Thorac Surg 1998;66:998-1001.[Abstract/Free Full Text]
  5. Loop F.D. Internal thoracic artery grafts—biologically better coronary arteries. N Engl J Med 1996;334:263-265.[Free Full Text]
  6. 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;61:1658-1665.[Abstract/Free Full Text]
  7. Diegeler A., Falk V., Matin M., et al. Minimally invasive coronary artery bypass grafting. Perfusion 1998;13:237-242.[Free Full Text]
  8. Flameng W.J. Role of myocardial protection for coronary artery bypass grafting on the beating heart. Ann Thorac Surg 1997;63:18-22.
  9. Malkowski M.J., Kramer C.M., Parvizi S.T., et al. Transient ischemia does not limit subsequent ischemic regional dysfunction in humans. J Am Coll Cardiol 1998;31:1035-1039.[Abstract/Free Full Text]
  10. Jaber S., Koenig S.C., Bhasker Rao B., et al. Role of graft flow measurement technique in anastomotic quality assessment in minimally invasive CABG. Ann Thorac Surg 1998;66:1087-1092.[Abstract/Free Full Text]
Accepted for publication January 27, 2000.





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