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Eur J Cardiothorac Surg 1999;16:S53-S57
© 1999 Elsevier Science NL

Perioperative management in minimally invasive coronary surgery

Department of Thoracic and Cardiovascular Surgery, La Pitié Hospital, Boulevard de l'Hôpital, 75013 Paris, France

^* Corresponding author. Tel.: +33-1-4217-7041; fax: +33-1-4217-7030 (Email: alain.pavie{at}psl.ap-hop-paris.fr).

	Abstract

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 
Objective: It is important to apply the same rules used for classical coronary revascularization to beating heart coronary surgery. The surgeons must have a strategy, and be prepared for adverse events, and complications. Methods: A careful analysis of the coronarography is essential to predict eventual contraindications or causes of possible operative difficulties. All the team must be involved in the surgical protocol. Three main problems need to be solved: the prevention of ischemia during the procedure, good stabilization of the anastomotic site and arterial occlusion. The first goal is reached by using a pre-conditioning technique or an intracoronary shunt. Vessel stabilization may be obtained by several methods: pressure adhesion devices, patch technique or suction devices. The final problem is to have a blood free field, this requires arterial occlusion which may be achieved in several ways: silastic Snares or sutures, aclan clamps, coronary occluder. Results: We have developed at la Pitié a protocol to apply all these principles. From February 1997 to November 1998, multiple revascularization was performed on 167 patients. A total of 344 coronary anastomosis were carried out (mean: 2.05 graft/patient). Conclusion: Some simple rules had to be applied to reduce the rate of complications to the minimum: a good clinical case selection, use of a routine protocol, and recognize the need to adapt the indications to the learning curve of the operator.

Key Words: Minimally invasive coronary artery revascularization • Beating-heart technique • Stabilization • Operative management

	1. Introduction

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 
The field of cardiac surgery was recently hit by the wave of the so called ‘mini-invasive surgery'. With surgical enthusiasm, numerous techniques have been proposed accompanied by claims sometimes rather exaggerated; at least often premature. However it must be said that this enthusiasm from all four corners of the world is in fact a real expression of clinical observations and definite technical progress. Many advances have been made in this field [1–4].

In the first phase, the proposed techniques were applicable to coronary surgery involving a single vessel, in particular the left anterior descending artery. The difficulties encountered had at least the merit to provoke ideas and stimulate the development of instruments allowing us at the present time to enlarge our indications to include certain patients with multiple vessel disease who may now be operated on without cardio-pulmonary bypass, however, by means of incisions which are not necessarily smaller than those used in classical surgery.

The learning curve phase of this field is probably complete. To day, it is time to standardize surgical procedures. It is important to try to apply to open coronary artery bypass (OPCAB) and minimal invasive direct coronary artery bypass (MIDCAB) the same rules used for classical coronary revascularization.

	2. General principles

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 
For MIDCAB and OPCAB, like for classical coronary surgery, it is essential not only to prepare a surgical strategy before commencing the procedure. But also to be prepared for complications, and to be able to change strategy as required. As for all surgical procedures the operative plan must be drawn up mentally before beginning in the operating room.

2.1 Coronarography analysis
The preparation of the surgical strategy begins with a careful analysis of the coronarography. It is essential to analyze: the number and nature of the vessels for grafting the anatomical data on each vessel: position, diameter, possible local difficulties such as calcifications, and intramyocardial situations. With the analysis of the coronarography and the clinical data, it is possible to predict some eventual contraindication or causes of possible operative difficulties.

If you consider that it is better to do a classical coronary revascularization with extra corporeal circulation, this must remain the technique of choice.

On the other hand, if you consider that with the given data and your own experience, it is possible to carry out a beating heart procedure, you have to choose the revascularization strategy, depending on single or multiple revascularization: type of revascularization, arterial or saphenous vein; the type of surgical incision: mini-incision such as mini-anterior thoracotomy, posterior thoracotomy, inferior incision, or full incision by sternotomy.

2.2 Surgical procedure
All the team has to be involved in the surgical procedure: surgeon, assistant and also anesthesiologist, nurses and perfusionnists. All must be trained and the different protocols must be written up to be used as a check list.

The anesthesiologist plays an important role, as usual, but particularly during beating heart surgery. He follows the whole duration of the procedure, and after having chosen the type of anesthesia, he controls the hemodynamic monitoring and the administration of cardiac drugs as required.

For beating heart surgery, three main problems need to be solved: the prevention of ischemia during the procedure; a good stabilization of the anastomotic site; and arterial occlusion.

2.2.1 Avoid ischemia
The first crucial point is the protection of the distal run-off site during fashioning of the anastomosis in order to avoid the occurrence of ischemia.

Some teams prefer a pre-conditioning technique. It is an indirect approach aimed to enhance myocardial tolerance during ischemic injury by exposing the myocardium to brief transient ischemia. A 5-min test occlusion was performed to determine the hemodynamic effect of artery occlusion, and 5 min of reperfusion was then allowed.

Another solution, inspired by the perfusion catheters of the angioplasty cardiologist, is the development of short flexible intracoronary shunts which may be introduced through the arteriotomy. The distal run-off site is thus perfused and safe from ischemia. After some controversy on the real benefit of these shunts, to day the benefit on the ventricular function is clearly proven for the left anterior descending artery (LAD) [5]. At La Pitié, we try to use shunts systematically, the only contraindication being difficulty of insertion due to the presence of plaques, calcifications or a very tortuous artery; where a high risk of damaging the endothelium exists. The need to have a shunt is particularly important in the case of a very large right coronary artery with a non-critical stenosis. Some others teams use the shunt only in selective conditions: proximal lesion, moderate stenosis on a great vessel, or when ischemia appears during the procedure (ST change or bradycardia). The shunt also allows the better control of bleeding in case of multiple collaterals, nevertheless the quality of the shunt is essential: transparency is of value in order to visualize the proper functioning of the shunt, it should be smooth and short to avoid endothelial damage [6].

During beating heart surgery, ischemic control is essential. The control of the ST segment on the EKG is mandatory [7].

It is clear that all these techniques must be applied very selectively and be subject to a rigorous evaluation and clinical follow-up.

The presence of connected defibrillators pads, on the operative field is essential. Pacing wires, specially in case of right coronary revascularization are useful in case of the occurrence of bradycardia. Troponine levels reflect ischemic consequences, many studies had already proven that they remain at a low level during beating heart surgery [8].

2.2.2 Vessel stabilization
Vessel stabilization is the second point to consider for beating heart surgery.

Initially a pharmacological approach was used by numerous teams in order to reduce the heart rate in a temporary or prolonged fashion. Adenosine [9], ß blockers of short duration of action such as esmolol or calcium inhibitors such as diltiazem [7] were used in this manner. At present, it is clear that with the improvement in the different types of stabilizers, they are less and less useful.

Much progress has been made in the mechanical methods of stabilization, initially assured by traction sutures, different models of stabilizing devices have been developed [10]. They can be classified in two families: (1) the pressure adhesion devices; and (2) the suction device. First of all stabilizers with limbs, which were fixed to the retractor. Whatever the model concerned all systems are based on the same principle, stability of the anastomotic site is obtained by exerting a certain pressure on the epicardium.

At la Pitié, we have developed a new ‘patch stabilization technique' (Fig. 1): two sutures (2.0 Ethibond) were passed under the artery proximally and distally to the selected anastomotic site, deeply into the myocardium. Two other sutures were placed on each side of the anastomotic site, parallel to the vessel. A square of PTFE patch (4x4 cm) was fenestrated to keep a peripheral edge of about 1 cm. Two adjacent sutures were passed through the patch in each corner fenestration and tied together. Gentle traction on the four tied sutures, allowed immobilization and exposure of the selected area.

View larger version (71K): [in this window] [in a new window]   Fig. 1. The ‘patch technique stabilization' from la Pitié.

2.2.3 Arterial occlusion
The last problem is to achieve a bloodless field, for this arterial occlusion is necessary. Several methods can be used: silastic Snares or sutures, aclan clamps, coronary occluder. An intra coronary shunt is an elegant way to solve the problem, it allows occlusion and perfusion. To reduce the risk of damage the endothelium, it is better to undersize the diameter of the shunt. Blowers are also useful with each technique.

2.2.4 Hemodynamic control
During the operation hemodynamic control is necessary. Classical techniques are sufficient. More sophisticated techniques such as Swan Ganz monitoring, analysis of left ventricular function by transesophageal echocardiography, were used initially to prove the efficacy and safety of the beating heart procedures. Today they are not necessary, except for research purposes.

On the other hand, it seems always necessary to have a perfusionnist on stand by. Even if with increased experience, the rate of conversion to CPB is very low, it can happens at any minute. The CPB circuit has to be systematically mounted and primed, however only in border line cases with very severe hemodynamic instability.

For each case, it is necessary to pre-load the patient, very often coronary patients have a low central venous pressure, it is necessary to start early. It is also important to have drugs prepared to be infused in case of need. Cell saver or similar techniques can be useful to reduce the need for transfusion.

Some general surgical principles may be applied, but it is necessary to adapt to each clinical case. Firstly it is necessary to choose the target vessel and, to avoid hemodynamic instability. It is also useful to try to reduce the duration of ischemia by first, implanting the saphenous vein on the ascending aorta.

Hemodynamic stability may be improved with a degree of Trendelenburg or lateral rotation of the table. ‘LIMA' Traction stitches on the Pericardium (described by Dr Ricardo LIMA in Brazil) facilitate the rotation of the heart to reach posterior circumflex branches.

Of course it necessary to be prepared at each moment for a change of strategy if an adverse situation occurs. A conversion to CPB is today very rare with the increased experience, but, it can happen. The procedure to has to be planned in advance.

The converse situation may also arise. An expected coronary revascularization on CPB may be concerted to a beating heart procedure due to unsuitable conditions such as calcified aorta, atheromatous aorta on poly-vascular patients or recent acute myocardial infarct.

2.3 La Pitié MIDCAB protocol
Applying all these principles, we have defined a simple protocol for beating heart surgery.

After harvesting of the internal mammary artery and saphenous vein, heparin was administrated in a dose of 1.5 mg/kg to keep activated clotting time greater than 300 s.

The operative time proceeds as follows:

• preparation of tissue stabilizer: anticipate the correct shape;

• adaptation of operative table position to facilitate the procedure for the operator and to assure hemodynamic stability;

• exposure of the heart with ‘Lima stitches', eventually slings;

• when hemodynamic stabilization is obtained, applied tissue stabilizer;

• exposure and dissection of coronary artery;

• put proximal occlusion false loop (Fig. 2), eventually a second one, distally;

• optimization of exposure and stabilization;

• arteriotomy;

• enlargement of the arteriotomy and introduction of coronary shunt;

• removal traction on proximal false loop;

• beginning of anastomosis using continuous running suture, starting by the heel, using a blower/mister if necessary;

• before the end of anastomosis, removal of coronary shunt;

• flush graft and coronary artery to avoid air embolism;

• check the anastomosis;

• removal with caution the tissue stabilizers.

View larger version (18K): [in this window] [in a new window]   Fig. 2. ‘False' double loop technique for temporary coronary occlusion.

	3. Results

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 
Applying this technique at La Pitié we have performed 226 beating heart coronary revascularizations. One hundred and ten patients were operated through a small anterior thoracotomy; the mammary artery was harvested by videoscopy and anastomosed on to the LAD.

From February 1997 to November 1998, multiple revascularization was performed mainly by sternotomy (162 patients) or through a lateral approach (5 patients).The 167 patients were mainly men (136 patients), with a mean age of 62.34±11.9-years-old. The indications were summarized on Table 1 . The most common indication was high risk patient (64%) with an intercurrent disease increasing the risk of CPB, on the other hand 60 patients had classical indications for coronary revascularization, but due to suitable coronary anatomy the decision was taken to do the operation on the beating heart.

	4. Conclusion

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 
For a safe beating heart MIDCAB procedure, some simple rules have to be applied to reduce the rate of complications to the minimum: good selection of clinical cases, use a routine protocol, and adapt your indications to your own learning curve.

	Footnotes

 
Presented at the International Symposium ‘Present State of Minimally Invasive Cardiac Surgery – Meet the Experts', Dresden, Germany, December 3– 5, 1998.

	References

Top Abstract 1. Introduction 2. General principles 3. Results 4. Conclusion References

 

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4. Nataf P, Lima L, Regan M, Benarim S, Pavie A, Cabrol C, Gandjbakhch I. Minimally invasive coronary surgery with thoracoscopic internal mammary artery dissection: surgical technique. J Cardiovasc Surg 1996;11:288-292.
5. Capasso F, Luccheti V, Caputo M, Grimaldi G, Caprio S, Angelini GD. Intraluminal shunt prevents left ventricular function impairment during beating heart coronary revascularization. Communication 031. Annual meeting of the EACTS, Brussels, Belgium, 20-23 September, 1998..
6. Levinson MM, Fooks GS. Coronary grafting using a temporary intraluminal shunt instead of heart-lung bypass. Ann Thorac Surg 1995;60:1800.[Abstract/Free Full Text]
7. Calafiore AM, DI Giammarco G, Teodori G, Bosco G, D'Annunzio E, Barsotti A, Maddestra N, Paloscia LG, Sciarra A, Fino C, Contini M. Left anterior descending coronary artery grafting via left anterior small thoracotomy without cardiopulmonary bypass. Ann Thorac Surg 1996;61:1658-1663.[Abstract/Free Full Text]
8. Babatasi G, Masseti M, Nataf P, Fradin S, Agostini D, Grollier G, Gerard JL, Khayat A. Minimally invasive coronary surgery: surgical considerations and assessment of cardiac troponin I. Eur J Cardio-thorac Surg 1998;14(Suppl 1):S82-S87.[Abstract/Free Full Text]
9. Robinson MC, Thielmeier KA, Hill BB. Transient ventricular asystole using adenosine during minimally invasive and open sternotomy coronary artery bypass grafting. Ann Thorac Surg 1997;63(Suppl 6):S30-S34.[Medline]
10. Borst C, Jansen E, Tulleken C, Grundeman PF, Mansvelt Beck HJ, van Dongen JW, Hodde KC, Bredee JJ. Coronary artery bypass grafting without cardiopulmonary bypass and without interruption of native coronary flow using a novel anastomosis site restraining device (Octopus). J Ann Coll Cardiol 1996;27:1356-1364.

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