Surgery for ventricular tachycardia in patients undergoing surgical ventricular restoration

Thứ sáu, 13 Tháng 5 2011 20:23 vietduc
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Surgery for ventricular tachycardia in patients undergoing surgical ventricular restoration{star}

Dan Lindbloma,b,*, Anders Albågea,b and Ulrik Sartipya,b

a Department of Cardiothoracic Surgery and Anesthesiology, Karolinska University Hospital, 171 76 Stockholm, Sweden
b Department of Molecular Medicine and Surgery, Karolinska Institutet, 171 76 Stockholm, Sweden

* Corresponding author: * Tel.: +46 8 517 700 00; fax: +46 8 33 19 31 Địa chỉ email này đã được bảo vệ từ spam bots, bạn cần kích hoạt Javascript để xem nó.

Summary

This article is a presentation of direct surgery for ventricular tachycardia in patients undergoing surgical ventricular restoration. The procedure includes a non-electrophysiologically guided subtotal endocardiectomy and cryoablation in addition to endoventricular patch plasty of the left ventricle. Coronary artery bypass surgery and mitral valve repair are performed concomitantly as needed. In our experience, this procedure yielded a 90% success rate in terms of freedom from spontaneous ventricular tachycardia, with an early mortality rate of 3.8%. Perioperative considerations and a short overview of the literature are presented.

Key Words: Cardiac surgical procedures • Coronary arteriosclerosis • Heart aneurysm • Heart failure, congestive • Ventricular remodeling • Ventricular tachycardia


History
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Surgical technique

Indications
In addition to the generally accepted indications for SVR, as presented by Menicanti and Di Donato [9], patients planned for SVR are assessed for presence of spontaneous or inducible-only ventricular arrhythmias (Schematic 1). We perform programmed electrical stimulation (PES) before surgery and after surgery, preferably in patients free from anti-arrhythmic medication, using a standard protocol including double or triple extra stimuli, three stimulation rates, and two locations. The protocol is terminated if sustained VT is induced. Sustained VT is defined as a tachycardia lasting more than 30 s or clinically requiring intervention before that [10]. In patients with preoperatively verified either spontaneous or inducible-only VT, we perform specific arrhythmia surgery in addition to SVR. Coronary artery bypass grafting and mitral valve repair is also performed when needed.


Figure 1
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 Schematic 1 Investigations and decision making in patients planned for surgical ventricular restoration.

SVR, surgical ventricular restoration; ICD, implantable cardioverter-defibrillator; PES, programmed electrical stimulation; VT, ventricular tachycardia.

Surgical procedure
Surgical ventricular restoration is performed with the technique described by Dor [11]. The operative procedure has been well illustrated by Menicanti and Di Donato [9].

Cardiopulmonary bypass and moderate systemic hypothermia is used. Transesophageal echocardiography is used to evaluate preoperative and postoperative left ventricular and mitral valve function, filling and de-airing. The aorta is cross-clamped, and myocardial protection is achieved with intermittent cold antegrade and retrograde blood cardioplegia.

The left ventricle is incised parallel to the interventricular septum and the left anterior descending artery (Video 1).


Figure 1
Click on image to view video		 Video 1 Opening of the left ventricle.

The left ventricle is incised parallel to the interventricular septum and the left anterior descending artery. If clots are present, they are removed. Four stay sutures will provide excellent exposure of the inside of the left ventricle and the mitral valve. The border-zone between aneurysm and normal myocardium is identified and the mitral apparatus is evaluated.

If present, mitral regurgitation is repaired by the Alfieri edge-to-edge technique (Video 2).


Figure 2
Click on image to view video		 Video 2 Edge-to-edge mitral repair.

If there is more than I+ mitral regurgitation the valve is repaired by a transventricular approach using the Alfieri edge-to-edge technique [12] in this case without annuloplasty. A 4-0 polypropylene suture, reinforced by pledgets of autologous pericardium is placed in the center of the anterior and posterior leaflets, creating a double-orifice mitral valve.

Concerns regarding sub-optimal long-term durability of the edge-to-edge plasty without annuloplasty in combination with SVR [13] have convinced us to change our policy and since 2003 we add annuloplasty to mitral valve repair during SVR, usually as a posterior plication suture as described by Menicanti et al. [14].

Endocardiectomy is performed on the interventricular septum, apex and anterolateral wall (Video 3).


Figure 3
Click on image to view video		 Video 3 Endocardiectomy.

An extensive, visually guided endocardiectomy is performed on the interventricular septum, apex and anterolateral wall. The endocardial resection is circumferential and extensive on all sides of the walls. The fibrotic endocardial tissue is removed by means of blunt and sharp dissection, effectively eliminating the substrate for arrhythmias. After completion of the endocardiectomy, the right ventricle is filled by partially occluding the venous line to identify and repair any small lesions in the interventricular septum. (From reference [18]. Reproduced with kind permission from Springer Science and Business Media.)

Cryo lesions are applied at the border of the endocardial resection line (Video 4).


Figure 4
Click on image to view video		 Video 4 Cryoablation.

A series of cryo lesions (Frigitronics CCS-200, CooperSurgical Inc., Trumbull, CT, USA –MMCTSLink 159) producing a continuous linear lesion are applied at remaining fibrotic tissue at the border of the endocardial resection line. We do not have experience with other devices, but in our opinion, any cryoablation device could be used. We routinely use a linear (T-shaped) probe, which is different from the one shown in the video. After cryoablation, the myocardium will need thawing by flooding the left ventricle with saline. (From reference [18]. Reproduced with kind permission from Springer Science and Business Media.)

The time to perform the endocardiectomy is 10 min and the total time for VT surgery (endocardiectomy and cryoablation) is approximately 20 min.

A purse-string suture is placed around the circumference of the left ventricle at the transition zone between aneurysm and normal myocardium (Video 5).


Figure 5
Click on image to view video		 Video 5 The Fontan suture.

A purse-string suture (2-0 polypropylene suture) is placed around the circumference of the left ventricle at the transition zone between aneurysm and normal myocardium (usually near the base of the papillary muscles) and tied down to determine the size of the new ventricular cavity. A sizing device (SVRTM System, Chase Medical, Richardson, TX, USA – MMCTSLink 160), not shown in this video, can be used to optimize size and shape of the reconstructed ventricle.

An endoventricular patch is secured over the ventricular opening (Video 6).


Figure 6
Click on image to view video		 Video 6 Endoventricular patch.

A bovine pericardial patch (Peri-Guard, Synovis Life Technologies Inc, St Paul, MN, USA –MMCTSLink 161), as in this patient, or a dacron patch (SVRTM System) is then secured over the ventricular opening with a running 2-0 polypropylene suture ensuring that all bites of this suture are placed around the Fontan suture to decrease the risk of patch dehiscence.

The ventricular free wall is then closed over the patch (Video 7).


Figure 7
Click on image to view video		 Video 7 Closing the left ventricle.

The ventricular free wall is then closed over the patch with a double running 2-0 polypropylene suture. These sutures are placed as deep as possible to minimize dead space outside the patch but at the same time protecting the left anterior descending artery.

The distal coronary anastomoses are usually performed after closure of the ventricle. If epiaortic scanning has excluded the presence of ascending aortic atheromatosis, proximal anastomoses are done with a sidebiting clamp, otherwise we use a single clamp technique.

Postoperative considerations (Schematic 1)
In patients with preoperative spontaneous VT, we perform an early postoperative PES before hospital discharge. If the PES is positive we provide the patient with an implantable cardioverter-defibrillator (ICD), otherwise not. In patients with preoperative, inducible-only VT, but no history of spontaneous VT, we perform a late PES after 3–6 months. If the PES is positive, we recommend implantation of an ICD, otherwise not.


Results

From July 1997 to December 2003, 53 consecutive patients underwent SVR including VT surgery for post-infarction, dyskinetic left ventricular aneurysm and VT at the Karolinska University Hospital [10]. There were no intraoperative deaths, but two patients died in the intensive care unit 1 and 50 days postoperatively, respectively, thus early mortality was 3.8%. Mean follow-up of operative survivors was 3.7±2.0 years. Overall survival was 94% at one year, 80% at three years, and 59% at five years. There was no arrhythmia-related death, no sudden death and no loss to follow-up. There was no difference in survival between patients with preoperative spontaneous or inducible-only VT. Surgical success in terms of arrhythmia control was defined as freedom from postoperative spontaneous VT in operative survivors. Five patients had spontaneous VT postoperatively, thus overall success rate was 90% (46 of 51 patients) [10].


Discussion

Studies have indicated that patients remain at high risk of ventricular arrhythmias after left ventricular reconstruction [15] and that there is a high incidence of sudden death late after surgery for left ventricular aneurysm without concomitant anti-arrhythmic surgery [16].

Adding direct surgery for VT (cryoablation and endocardiectomy) in patients undergoing SVR, as originally described by Dor [7], does not seem to increase morbidity or mortality [17].

Therefore, it is our conclusion that patients scheduled for SVR should be preoperatively assessed for ventricular arrhythmias.If ventricular tachycardia is present (spontaneous or inducible-only), specific arrhythmia surgery should be performed concomitantly. The postoperative results should be verified by means of electrophysiology studies. If ventricular tachycardia can no longer be induced, the patient should be considered cured in this aspect and implantation of an ICD should be avoided.



Footnotes

{star} The authors have no potential conflicts of interest to disclose. Back


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