In the cryosurgical approach the atrial incisions of the standard maze procedure are replaced by linear cryolesions. The cryosurgical procedure results in a shorter and technically less demanding procedure. Whether surgical incisions or cryolesions are used to perform the Maze procedure, it is essential to create transmural atrial lesions to prevent late recurrence of atrial fibrillation. Since the cryolesions actually can be observed as they develop it is a simple matter to determine when transmural ablation has or has not occurred.
The cryosurgical surgical technique described herein has become our standard procedure for the treatment of all types of medically refractory atrial fibrillation with and without associated acquired or congenital heart diseases.
The right atrial cryolesions can be performed without the use of cardiopulmonary bypass, but after full heparinization.
A purse-string suture is placed in the posterior-lateral right atrium and a linear cryoprobe is inserted through the purse-string into the inside of the right atrium. A cryolesion is placed in a cephalad direction into the postero-lateral aspect of the superior vena cava (SVC) orifice and away from the SA node [Figure 2]. Using the same purse-string suture, a second cryolesion is placed into the orifice of the inferior vena cava (IVC) to complete the longitudinal lesion from the SVC to the IVC [Figure 3]. Through the same purse-string a third lesion is made along the lateral wall of the right atrium down to inter-atrial septum and the right pulmonary veins is placed [Figure 4 - closed arrow]. The first purse-string suture is tied and a second purse-string is placed near the AV groove of the free-wall of the right atrium. The cryoprobe is inserted through this second purse-string suture to create the linear “T” lesion across the lower right atrium [Figure 5]. Using the same purse-string suture, the cryolesion is extended down to the level of the tricuspid valve annulus at the junction of the anterior and posterior commissures [Figure 5 and 6 – closed white arrows].
|Figure 2||Figure 3||Figure 4|
|Figure 5||Figure 6|
After the completion of the right atrial cryolesions, cardiopulmonary bypass is instituted. For placement of the left atrial cryolesions we use slightly different techniques for patients having an isolated Maze procedure and those who are also undergoing mitral valve surgery. The technique also varies in a few details depending upon whether the surgical approach is through a median sternotomy or a small right thoracotomy.
The inter-atrial groove is dissected completely and the right superior and right inferior pulmonary veins are dissected free circumferentially. One linear cryoprobe is placed posterior to the right pulmonary veins as they enter the left atrium. A second identical cryoprobe is placed on the anterior surface of the veins in the same plane. The cryoprobes are then “squeezed” together firmly and two-minute cryolesion is created by freezing with both probes. This result is a transmural cryolesion around the orifices of the right pulmonary veins. A left ventricular vent is placed via the right superior pulmonary vein [Figure 7]
A standard left atriotomy is performed after placement of the aortic cross clamp and instituting cardioplegic arrest. A lesion connecting the inferior right and left inferior pulmonary veins is performed using the linear cryoprobe [Figure 9]. Creating a lesion from the pulmonary veins connecting line down to the posterior mitral valve annulus with the linear cryoprobe and ablation of the coronary sinus with the 15mm right angle probe concludes the procedure [Figure 10- arrows]. Cryoablation of the coronary sinus is performed on the epicardial surface [Figure 10- open arrow].
|Figure 9||Figure 10|
This technique decreases the aortic cross-clamp time by reducing the number of cryolesions that are necessary after opening the left atrium to three for those that are marked with arrows in figures 9-10.
If an isolated cryomaze procedure is being performed the left atriotomy is then closed, and the procedure completed; however, if a combined mitral valve procedure is required, the valve surgery is performed at this time.
Nodal rhythm management
Publication Date: 18-Mar-2005
Last Modified: 18-Mar-2005