HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Johannes M. Albes Karl R. Karsch Gerhard Ziemer Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Menon, A. K. Articles by Ziemer, G. Search for Related Content PubMed PubMed Citation Articles by Menon, A. K. Articles by Ziemer, G. Related Collections Minimally invasive surgery

Ann Thorac Surg 2002;73:1418-1423
© 2002 The Society of Thoracic Surgeons

---

Original article: cardiovascular

Occlusion versus shunting during MIDCAB: effects on left ventricular function and quality of anastomosis

^a Department of Thoracic, Cardiac and Vascular Surgery, Eberhard-Karls-University, Tübingen, Germany
^b Department of Cardiology, Eberhard-Karls-University, Tübingen, Germany

Accepted for publication January 23, 2002.

* Address reprint requests to Dr Menon, Department of Thoracic, Cardiac, and Vascular Surgery, Eberhard-Karls-University, Hoppe-Seyler-Strasse 3, D-72076 Tübingen, Germany
e-mail: asmenon{at}med.uni-tuebingen.de

	Abstract

Top Abstract Introduction Material and methods Results Comment References

 
Background. Minimally invasive direct coronary artery bypass is an established clinical procedure for revascularization of the left anterior descending coronary artery. Mechanical stabilization and temporary occlusion is currently used to perform the anastomosis of the internal thoracic artery to the left anterior descending coronary artery. However, critical reduction of cardiac function can occur as a result of temporary ischemia. The purpose of this study was to evaluate whether ischemic sequelae can be avoided by using temporary intraluminal shunts and whether this alters early outcome.

Methods. Thirty-five patients underwent minimally invasive direct coronary artery bypass revascularization using a mechanical stabilizer. In group A (n = 20), the anastomotic site was temporarily occluded by tourniquets. In group B (n = 15), temporary intraluminal shunts were inserted into the anastomotic site without any occlusion of the left anterior descending coronary artery. Anastomosis of the internal thoracic artery to the left anterior descending coronary artery was performed in an identical fashion. A Swan-Ganz catheter was inserted, and transesophageal echocardiographic measurements were obtained for analysis of left ventricular (LV) function. Regional wall motion, cardiac index, stroke volume index, systolic and diastolic LV diameters, and fractional area change were measured during four periods: at the start of the operation (baseline), placement of the stabilizer (stabilization), left anterior descending coronary artery occlusion (occlusion) or insertion of temporary intraluminal shunts (shunt), and 30 minutes after reperfusion (reperfusion). Angiograms were obtained 4 to 6 days postoperatively.

Results. In group A, LV performance, cardiac index, stroke volume index, and fractional area change decreased during occlusion whereas systolic diameters increased. Almost two myocardial segments per patient developed severe hypokinesia in the perfusion area. These changes disappeared after 30 minutes of reperfusion, with increased LV function. In group B, LV function remained stable whereas hypokinetic wall motion was only detected in 2 patients. Early angiograms revealed 90% of the grafts were patent in group A versus 100% in group B. The need for percutaneous intervention during the first 6 months was 20% in group A versus 6.7% in group B.

Conclusions. The use of temporary intraluminal shunts resulted in reduced acute ischemia and revealed wall motion abnormalities and maintained LV function. Furthermore, this technique suggests an improvement of early graft patency and a lower reintervention rate within the first 6 postoperative months. Thus, use of temporary intraluminal shunts appears to be superior to the occlusion technique early after minimally invasive direct coronary artery bypass procedures.

	Introduction

Top Abstract Introduction Material and methods Results Comment References

 
During the last 5 years, minimally invasive direct coronary bypass (MIDCAB), ie, the anastomosis of the internal thoracic artery (ITA) to the left anterior descending coronary artery occlusion (LAD) through a left anterior mini-thoracotomy without the use of cardiopulmonary bypass, has become an established procedure. First described by Kolesov in 1967 [1], it was revitalized by Benetti and colleagues in 1989 [2], but found wider acceptance when used by Subramanian and associates [3] and Calafiore and coworkers [4] in larger series.

Although MIDCAB is widely and successfully used in selected patients, there are still some technical problems that are leading to left ventricular (LV) ischemia owing to temporary LAD occlusion during suturing the anastomosis. This ischemia can lead to reduced LV function and to a reduction in cardiac output [5]. The deleterious effect of snugger occlusion of the LAD caused by the use of polyethylene sutures has been described previously [6, 7].

Preliminary clinical data suggest that the use of temporary intraluminal shunts (TILS) during beating heart operations through a sternotomy may be safer [8]. Long-term follow-up data, however, especially with angiograms, are limited and do not allow meaningful analysis. Early experimental data showed a possible protective effect of TILS on the myocardium when compared with the occlusion technique [8]. It is still open to question whether a temporary shunt inserted behind the critical lesion indeed will allow sufficient blood flow to the distal vasculature to avoid ischemia and to conserve normal LV function. Another important problem is the quality of anastomosis in the subacute and follow-up period, also in regard to reintervention rates.

The purpose of this clinical trial was to determine whether the use of TILS can reduce or avoid ischemia in comparison to the conventional technique and whether the use of TILS has advantages on the restenosis rate during early follow-up.

	Material and methods

Top Abstract Introduction Material and methods Results Comment References

 
Thirty-five consecutive patients with single-vessel (62.9%) or double-vessel (37.1%) coronary artery disease underwent MIDCAB procedure performed by one surgeon. Two groups of patients were compared retrospectively: Patients of group A were operated on from March to November 1998 with standard temporary LAD occlusion (n = 20). From November 1998 to June 1999 a TILS was inserted during every operation (group B) in 15 patients. This was because these shunts were not available for us before November 1998.

The demographic data are provided in Table 1. The majority of the patients had severe LAD stenosis of more than 70%, 3 patients had an occlusion of the LAD (8.6%). Age and body surface area were similar in both groups. All patients had normal or slightly reduced LV function with an ejection fraction of more than 40%. Although most patients showed a hypokinetic anterior wall, none of them had an akinetic or dyskinetic anterior wall preoperatively. In the patients with LAD occlusion, a myocardial scintigram exhibited viability of the anterior wall.

One male patient in group B had had mechanical aortic valve replacement several years ago and showed a subtotal LAD lesion. All operations were performed on an elective basis.

Operative technique
The patients were placed under general anesthesia and ventilated with a double-lumen endotracheal tube, allowing for single-lung ventilation when clinically necessary.

As described previously [5], hemodynamic monitoring was established using a radial artery catheter, a triple-lumen central venous catheter, and a Swan-Ganz thermodilution pulmonary artery catheter. A 3.7/5.0-MHz multiplan transesophageal echocardiography transducer (Hewlett-Packard HP OmniPlan, Hewlett-Packard, Boeblingen, Germany) was advanced to the transgastric level, exhibiting the midpapillary area of the LV for monitoring of LV function by means of the short-axis and long-axis view. It was connected to the console of a Hewlett-Packard HP Sonos 2500.

Skin electrodes were applied to allow for external defibrillation or pacing, and the patient was placed in 20° to 30° right anterolateral decubitus position. A skin incision of 8 to 10 cm was performed in the fourth intercostal space on the anterior part of the left chest. After insertion of a Cardio Thoracic Systems retractor (CTS MIDCAB System, Cardio Thoracic Systems, Cupertino, CA), the left ITA was mobilized over three intercostal spaces toward the apex of the left chest.

The pericardium was opened using an oblique incision, followed by identification of the LAD. After the anastomotic site was selected, 100 IU heparin per kilogram body weight was given intravenously, and the ITA was dissected distally. One hundred milligrams of lidocaine was administered intravenously before direct manipulations on the heart.

In group A, the selected LAD segment was locally occluded by means of two 4-0 Prolene (Ethicon, Somerville, NJ) tourniquet sutures over silicone tubes. If no adverse events occurred, such as critical hemodynamic compromise, changes of wall motion of LV segments, or significant ST-segment elevations detected within 2 minutes, the LAD was incised and the ITA was anastomosed using one running 7-0 monofilament suture.

In group B, an AnastaFLO (Baxter, Unterschleissheim, Germany) intraluminal shunt (TILS) was chosen according to the size of the anastomotic area of the target vessel. The epicardial stabilizer (CTS MIDCAB System) was applied to the epicardium under gentle pressure until sufficient immobilization of the anastomotic site of the LAD was achieved. The LAD then was incised, and an appropriate intraluminal shunt from 1.5 to 2.0 mm diameter was inserted. Special care was taken not to occlude the vessel at any time. The anastomosis was performed in the identical fashion as described above. Before final knotting, the TILS was removed, again without any occlusion of the vessel. The ITA pedicle was fixed at the epicardium with a single suture. A chest tube was inserted for drainage of the left chest cavity, and 50 IU/kg protamine was administered.

During all echocardiographic and hemodynamic measurements any application of positive inotropic drugs, ß-adrenergic blockers, or calcium-channel antagonists was completely avoided. The central venous pressure was maintained between 7 and 10 mm Hg.

Data acquisition
A complete set of hemodynamic variables was measured by means of the Swan-Ganz pulmonary artery catheter and thermodilution cardiac output computer (Hewlett- Packard).

The multiplane transesophageal echocardiography transducer (3.7/5.0 MHz; Omniplan; Hewlett-Packard) was positioned at the height of the midpapillary muscle area of the LV. The end-diastolic and end-systolic diameters in both, and the anterior-posterior and septal-lateral planes were determined in the short-axis view, as well as the end-diastolic and end-systolic diameter in the apical region in the long-axis view.

Analysis of LV function was performed by continuous calculation of the fractional area change (FAC) based on acoustic quantification by Hewlett-Packard equipment.

Data were sampled at four time intervals before, during, and after the operation: at the beginning of the operation (baseline), after application of the epimyocardial stabilizer (stabilizer), after an average of 10 to 15 minutes of LAD occlusion in group A (occlusion), after insertion of the temporary intraluminal shunt (TILS) in group B, and finally after 30 minutes of restoration of blood flow from the ITA to the LAD (reperfusion) with the stabilizer being removed. Data were analyzed using commercially available software programs for personal computers. For comparison of group means the Student’s t test for paired data was used.

	Results

Top Abstract Introduction Material and methods Results Comment References

 
Situs preparation
Baseline data
No significant differences were seen in the echocardiographic measurements of LV diameters (Tables 2, 3), as well as LV function (FAC) cardiac index (CI), and stroke volume index (SI) between the groups before intervention (Figs 1–3).

View larger version (29K): [in this window] [in a new window]   Fig 1. Fractional area change for patients undergoing operation with either occlusion of the left anterior descending coronary artery (black bars) or placement of a temporary intraluminal shunt (gray bars). Data are shown as mean ± standard deviation. (*p < 0.05 versus previous condition.)

View larger version (29K): [in this window] [in a new window]   Fig 2. Cardiac index for patients undergoing operation with either occlusion of the left anterior descending coronary artery (black bars) or placement of a temporary intraluminal shunt (gray bars). Data are shown as mean ± standard deviation. (*p < 0.05 versus previous condition.)

View larger version (33K): [in this window] [in a new window]   Fig 3. Stroke volume index for patients undergoing operation with either occlusion of the left anterior descending coronary artery (black bars) or placement of a temporary intraluminal shunt (gray bars). Data are shown as mean ± standard deviation. (*p < 0.05 versus previous condition.)

Anastomotic procedure
The mean time for performing the anastomosis was slightly longer in group B than in group A (25.4 versus 23 minutes.).

Group A: effect of regional left anterior descending coronary artery occlusion
After 10 minutes of LAD occlusion, the FAC showed a significant decrease (p = 0.004) compared with values after stabilizer placement (Table 2, Fig 1). This was associated by a decrease of CI and SI (p = 0.001; Figs 2, 3). In addition significantly larger end-systolic diameters of the LV (Table 2) compared with the measurements under stabilization alone could be detected.

All patients with previously normal wall motion showed new regional wall motion abnormalities in the perfusion area of the LAD. In patients with preexisting wall motion abnormalities, a worsening to akinesia was observed. The incidence of wall motion abnormalities was higher in the septal and apical areas (Table 4). Furthermore, these changes occurred in an average of 1.8 segments per patient. Two patients with preexisting LAD occlusion revealed no change in regional wall motion.

Reperfusion
Thirty minutes after completion of the anastomosis and reperfusion of the LAD in group A, the end-systolic diameters in the midpapillary area (end-systolic diameter anterior-posterior and end-systolic diameter septal-lateral of LV) showed a significantly improved fractional shortening (p = 0.001 [anterior-posterior]; p = 0.001 [septal-lateral]), although the diastolic diameters remained unchanged (Table 2) when compared with the occlusion and the baseline data. As a consequence, the increase of the FAC indicated a significantly improved LV function (p = 0.001; Fig 1). The hemodynamic variables showed a hyperemic phenomenon: CI (p = 0.002) and SI (p = 0.041) significantly exceeded the baseline and occlusion values (Figs 2 and 3).

There was a complete normalization of newly acquired wall motion abnormalities 30 minutes after restoration of blood flow to the LAD.

In group B, the FAC as well as the CI and SI showed moderate increase (Figs 1–3). The end-systolic diameters of the septum and apex of the LV decreased, whereas the diastolic diameter values remained unchanged (Table 3). In contrast to group A, no significant changes compared with the previous measurements with the shunt in situ were observed (Table 2 versus 3).

Postoperative angiography
Between days 4 and 6 all 35 patients after MIDCAB underwent angiography of the ITA graft. The results are provided in Table 5. The patency rate was 90% in group A versus 100% in group B. In 2 patients of group A and 1 patient of group B, significant lesions at the site of the distal anastomosis were found, and all 3 patients underwent subsequent percutaneous transluminal coronary angioplasty. Two additional patients of group A showed luminal irregularities before or after the anastomotic site, which correspond to the position of the occluder. Although no relevant lesions were present, these patients had a close clinical and angiogram during follow-up.

	Comment

Top Abstract Introduction Material and methods Results Comment References

In our first experience with the MIDCAB procedure with on-line evaluation of LV function and registration of hemodynamic changes during this operation, we were able to demonstrate a significant impairment of local LV wall motion and LV function when mechanical stabilization and temporary LAD occlusion was used [5]. We could show that the epimyocardial stabilizer did not lead to deterioration of LV function whereas the LAD occlusion led to severe impairment of FAC, CI, and SI. These changes were most probably related to the extent of ischemia induced by occlusion of the LAD (Table 4). These ischemia-related effects were followed by a hyperemic response after 30 minutes of reperfusion (Figs 1–3). Recently, use of TILS has been advocated to be superior to LAD occlusion technique in early experimental and clinical trials.

Dapunt and coworkers [9] described an experimental MIDCAB model in pigs, and Rivetti and Gandara [8] and Lucchetti and colleagues [10] demonstrated positive effects of temporary shunts during LAD revascularization. However, these procedures were performed during conventional sternotomy and under beating heart conditions. Furthermore, the postoperative quality of the anastomosis was not verified by angiography in the subacute state and during follow-up [8, 10].

Our assumption was that MIDCAB offers ideal conditions to test the hypothesis that ischemia can be reduced and operative success might be improved by the use of TILS. After a short learning curve, the handling of these shunts was easy. In the two patients with hypokinetic LV areas under use of TILS, there was no significant change in LV function. Both of these vessels showed a small diameter of barely 1.5 mm; it is possible this led to an inadequate flow through the shunt.

The option of continuous perfusion allows more time for preparation of the anastomosis, thus making the procedure safer and less traumatizing than during ischemic conditions with LAD occlusion. In addition, LAD snaring and occlusion with vessel injury caused by the tourniquets can be avoided, resulting in a better long-term outcome [6, 7].

Our results demonstrate that LV performance as determined by the end-diastolic and end-systolic diameters is stable during operation using TILS, which was obviously a result of the alleviation of ischemia. No major changes could be detected in the hemodynamics, namely CI and SI (Figs 2, 3), and the echocardiographic-sampled FAC (Fig 1).

In both our previously performed and the current study, no signs of myocardial stunning could be found after reperfusion as had been reported by Dapunt and coworkers [9]. The major reason for this discrepancy might be related to the animal model used without coronary artery disease and relatively long occlusion.

Aside from the acute intraoperative benefits of TILS, this technique was also superior to coronary occlusion in the short-term and long-term follow-up period. Patients operated on with the use of TILS had a considerably better outcome with fewer restenoses and reinterventions. However, because of the limited number of patients enrolled in this pilot study, these differences are preliminary and need validation in a larger trial.

From the surgeon’s perspective, the use of TILS in MIDCAB procedures is safe and beneficial. It provides an unimpaired LV function during operation and allows easier and safer accomplishment of the anastomosis.

	References

Top Abstract Introduction Material and methods Results Comment References

 

1. Kolesov V.I. Mammary artery-coronary artery anastomosis as method of treatment for angina pectoris. J Thorac Cardiovasc Surg 1967;54:535-544.[Medline]
2. Benetti V.J., Naselli G., Wood M., Geffner L. Direct myocardial revascularization without extracorporeal circulation: experience in 700 patients. Chest 1991;100:312-316.[Medline]
3. Subramanian V.A., Sani G., Benetti F.J., Calafiore A.M. Minimally invasive coronary bypass surgery: a miulticenter report of preliminary clinical experience. Circulation 1995;92(Suppl 1):1-645.[Abstract/Free Full Text]
4. 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]
5. Jurmann M.J., Menon A.K., Haeberle L., Salehi-Gilani S., Ziemer G. Left ventricular geometry and cardiac function during minimally invasive coronary artery bypass. Ann Thorac Surg 1998;66:1082-1086.[Abstract/Free Full Text]
6. Hangler H.B., Pfaller K, Antretter H., Miller L.C., Bonatti J.O. Human coronary artery injury after local occlusion on the beating heart. Poster and short oral presentation (C150) at the 2nd annual meeting of the International Society for Minimally Invasive Cardiac Surgery (ISMICS). Paris, France: Palais de Congrès, 1999:21-22.
7. Hake U., Hillker M., Oelert H. ‘Soft’ snaring of the coronary artery in minimally invasive coronary surgery. Thorac Cardiovasc Surg 1998;46:380-381.[Medline]
8. Rivetti L.A., Gandara S.M.A. Initial experience using an intraluminal shunt during revascularization of the beating heart. Ann Thorac Surg 1997;63:1742-1747.[Abstract/Free Full Text]
9. Dapunt O.E., Raji M.R., Jeschkeit S., et al. Intracoronary shunt insertion prevents myocardial stunning in a juvenile porcine model absent of coronary artery disease. Eur J Cardiothorac Surg 1999;15:173-179.[Abstract/Free Full Text]
10. Lucchetti V., Capasso F., Caputo M., et al. Intracoronary shunt prevents left ventricular function impairment during beating heart coronary revascularization. Eur J Cardiothorac Surg 1999;15:255-259.[Abstract/Free Full Text]

This article has been cited by other articles:

				D. Mukherjee, K. Ahmed, K. Baig, V. M. Patel, A. Darzi, and T. Athanasiou Conversion and Safety in Off-Pump Coronary Artery Bypass: A System Failure That Needs Re-Emphasis Ann. Thorac. Surg., February 1, 2011; 91(2): 630 - 639. [Abstract] [Full Text] [PDF]

				G. V. Letsou, G. L. Grunkemeier, A. L. Salaskar, C. Bavare, Y. Wu, and M. M. Rampurwala Selective Left Anterior Descending Shunting Provides Effective Off-pump Myocardial Protection Ann. Thorac. Surg., January 1, 2010; 89(1): 24 - 29. [Abstract] [Full Text] [PDF]

				J. Bergsland, P. S. Lingaas, H. Skulstad, P. K. Hol, P. S. Halvorsen, R. Andersen, M. Smastuen, R. Lundblad, J. Svennevig, K. Andersen, et al. Intracoronary Shunt Prevents Ischemia in Off-Pump Coronary Artery Bypass Surgery Ann. Thorac. Surg., January 1, 2009; 87(1): 54 - 60. [Abstract] [Full Text] [PDF]

				H. Hangler, L. Mueller, E. Ruttmann, H. Antretter, and K. Pfaller Shunt or Snare: Coronary Endothelial Damage due to Hemostatic Devices for Beating Heart Coronary Surgery Ann. Thorac. Surg., December 1, 2008; 86(6): 1873 - 1877. [Abstract] [Full Text] [PDF]

				R. M. Mentzer Jr, M. S. Jahania, and R. D. Lasley Myocardial Protection , January 1, 2008; 3(2008): 443 - 464. [Full Text]

				S. P. Collison, A. Agarwal, and N. Trehan Controversies in the use of intraluminal shunts during off-pump coronary artery bypass grafting surgery. Ann. Thorac. Surg., October 1, 2006; 82(4): 1559 - 1566. [Abstract] [Full Text] [PDF]

				J. Wippermann, J. M. Albes, R. Bruhin, M. Hartrumpf, R. Vollandt, H. Kosmehl, and T. Wahlers Chronic ultrastructural effects of temporary intraluminal shunts in a porcine off-pump model Ann. Thorac. Surg., August 1, 2004; 78(2): 543 - 548. [Abstract] [Full Text] [PDF]

				M. Zimarino, S. Gallina, M. Di Fulvio, M. Di Mauro, G. Di Giammarco, R. De Caterina, and A. M. Calafiore Intraoperative ischemia and long-term events after minimally invasive coronary surgery Ann. Thorac. Surg., July 1, 2004; 78(1): 135 - 141. [Abstract] [Full Text] [PDF]

				H. B. Hangler, K. Pfaller, E. Ruttmann, D. Hoefer, T. Schachner, G. Laufer, and H. Antretter Effects of intracoronary shunts on coronary endothelial coating in the human beating heart Ann. Thorac. Surg., March 1, 2004; 77(3): 776 - 780. [Abstract] [Full Text] [PDF]

				J. Wippermann, J. M. Albes, H. Brandes, H. Kosmehl, R. Bruhin, and T. Wahlers Acute effects of tourniquet occlusion and intraluminal shunts in beating heart surgery Eur J Cardiothorac Surg, November 1, 2003; 24(5): 757 - 761. [Abstract] [Full Text] [PDF]

				R. M. Mentzer Jr., M. S. Jahania, and R. D. Lasley Myocardial Protection , January 1, 2003; 2(2003): 413 - 438. [Full Text]

This Article Abstract Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Author home page(s): Johannes M. Albes Karl R. Karsch Gerhard Ziemer Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Menon, A. K. Articles by Ziemer, G. Search for Related Content PubMed PubMed Citation Articles by Menon, A. K. Articles by Ziemer, G. Related Collections Minimally invasive surgery