Modified Endoventricular Circular Plasty (Dor procedure)

Patient Selection

Certain patients who present following a transmural anterior wall myocardial infarct with an akinetic or dyskinetic wall segment, have been shown to benefit from endoventricular circular patch plasty as described by Dor.

Reconstructive surgery of the altered left ventricular topography results in a permanent improvement in the ventricular wall function, including non-ischemic zones remote from the anterior wall left ventricular aneurysm.

Operative Steps

The patient is anesthetized in the supine position and intubated with a single lumen endotracheal tube.

The patient should be prepped and draped for full sternotomy. A transesophageal echography probe is passed to assess left ventricle function, evaluate the aneurysm, assess for the presence of intracavitary thrombus and rule out associated valve disease. It is also useful to assess the clearance of intracardiac air at the completion of the procedure. Approximate 90% of the patients undergo concomitant coronary artery bypass grafting and 45% undergo Mitral Valve repair.

A median sternotomy is performed and the heart exposed. After the patient is heparinized, an aortic cannula is inserted in the distal ascending aorta, and double stage venous cannula is placed into the right atrium. The patient is placed on cardiopulmonary bypass and maintained warm.

If coronary artery bypass is to be performed, a retrograde cardioplegia cannula is inserted through the right atrium into the coronary sinus. The aorta is cross-clamped and antegrade cold blood cardioplegia is given. This is followed by cold blood retrograde cardioplegia, which is repeated every 15 minutes.

After the associated pathologies are treated, a dose of warm retrograde cardioplegia is given and the aorta is unclamped. With the heart contracting, the aneurysm (which most of the time is located in the apical anterior wall) is examined. If clot was identified in the aneurysm on TEE this aneurysm is opened and the clot removed prior to removing the clamp.

The aneurysm is entered using 15-blade knife. Make sure that the entrance point is at least 1.5 to 2.0 cm from the LAD, which will facilitate subsequent closure.

The cavity of the left ventricle is carefully examined and any intracavitary thrombus extracted. Visual inspection and palpation identify the edgebetween the aneurysmal scar tissue and viable contracting myocardial.

After the extension of the endocardial scarring is determined, a purse-string suture of 2-0 polypropylene is placed around the entire circumference of the base of the aneurysm at the junction of the scar and normal myocardium. The purse-string suture is then tied down snuggly from the inside restoring the ventricular cavity geometry.The degree of tightening of this suture will determine the size of the remaining opening of the ventricle.

If the remaining opening of the ventricle is larger than 3 centimeters, a second purse-string suture of 2-0 polypropelene can be placed 4 mm distal to the first one. With the use of this second purse-string we have been successful decreasing the size of the ventricular opening to less than 3 cm and avoid the use of patch material to close the ventricle.

If the ventricular opening is larger than 3 cm despite the second purse-string, it can be closed using a hemashield patch, as described by Dor. The endocardial patch is secured in place with interrupted vertical mattress sutures of 3-0 polypropylene placed through the edges of the patch and then transmurally from the endocardium to the epicardium at the level of the purse-string suture and tied over a felt pledget.

The edges of the ventricular free wall are then approximated using a interrupted mattress sutures of 3-0 polypropylene tied over felt strip and reinforced with a continuous running suture of 3-0 polypropylene.

Hemostasis is ascertained and patient is slowly weaned from cardiopulmonary bypass, after transesophageal echocardiogram confirms adequate deairing of the left ventricle. Transesophageal echocardiogram is repeated, at this time, to reevaluate the left ventricle contractility and the mitral valve function.

Anticoagulation is reversed and the aorta and right atrium are decannulated. Atrial and ventricular pacing wires are inserted and secured. Mediastinal drainage tubes are placed. The sternotomy is approximated with stainless steel wire. The pectoralis fascia, subcutaneous tissue and skin are closed with absorbable suture.

No anticoagulation is necessary postop, unless required for associated pathologies.

Tips & Pitfalls

1. Intra-operative transesophageal echocardiography is mandatory to evaluate the contractility of the left ventricle, rule out mitral or aortic valve pathology, and the presence of intracavitary thrombus or intracardiac shunts.
2. Direct palpation of the left ventriclar wall with the heart beating, after the cross clamp has been removed, greatly assists in the differentiation of non-contractile scar tissue from viable myocardium.
3. For patients with a dilated mitral valve annulus and mitral insufficiency, repair of the mitral valve can be accomplished through the ventriculotomy using an Alfieri stitch.
4. For patients presenting with recurrent ventricular tachycardia and a calcified aneurysm, a subendocardial resection of the scar tissue and cryoablation at the level of the transitional zone can be performed with good results.
5. Following endoventricular circular plasty, patching of the remaining ventricular opening may be important for patients with large ventricular aneurysms. For some of these patients, the remaining ventricular cavity may become too small to generate an adequate stroke volume. Patching the ventricular opening will increase the left ventricular end-diastolic volume and consequently the stroke volume.

References

1. DiDonato M, Sabatier M, Toso A, Barletta G, Baroni M, Dor V, Fantini F. Regional myocardial performance of non-ischaemic zones remote from anterior wall left ventricular aneurysm. Eur Heart J 1995;16:1285-92.
2. DiDonato M, Sabatier M, Dor V, Toso A, Maioli M, Fantini F. Akinetic versus dyskinetic postinfarction scar: Relation to surgical outcome in patients undergoing endoventricular circular patch plasty repair. J Am Coll Cardiol 1997;29(7):1569-75.
3. Dor V, Saab M, Coste P, Kornaszewska M, Montiglio I. Left ventricular aneurysm: a new surgical approach. Thorac Cardiovasc Surg 1989;37:11-19.
4. McCarthy PM, Young JB, Sarling RC, Blackstone EH, Smedira NG, Buda T, Goormastic M, Navia JL, Hoercher KJ. Anterior infarct exclusion surgery for ischemic cardiomyopathy. Circulation 1999;100:18:I-514