The Total Thoracoscopic Maze Procedure
As performed at The Ohio State University, the total thoracoscopic maze is a closed-chest, beating-heart, truly minimally invasive procedure. This innovative surgical treatment approach is teamed with comprehensive testing to assure that all potential causes are completely treated. Outcomes in patients who have had the total thoracoscopic maze procedure compare very favorably to those who have undergone catheter ablation or other types of maze surgery such as the Wolf Mini-Maze.
To begin the procedure, the patient is asleep and placed in the supine position, with a soft roll placed between the spine and the left scapula to elevate the left flank. Four tiny incisions of half an inch in length or less are made on each side of the chest. The pericardium, or fibrous sac enclosing the heart, is opened away from the phrenic nerve, which is responsible for innervating the diaphragm. In this, as in every maneuver of the operation, the thoracoscope provides clear, magnified visualization of all key anatomic structures. This technology enhances both the safety and precision of every maneuver. No computer-enhanced imaging is necessary, since all treated regions of the heart are seen in great detail with the thoracoscope.
If you would like more information about totally thoracoscopic maze surgery performed by Dr. John Sirak at The Ohio State University, request a phone consultation or call Dr. Sirak's appointment phone at 614-293-5502.
Total Thoracoscopic Maze Surgery in Detail
The total thoracoscopic maze consists of five major technical components which are all verified in real time, thereby systematically addressing all mechanisms responsible for atrial fibrillation.
- Bilateral pulmonary vein isolation
- Mapping and ablation of epicardial autonomics
- Extended lesions encompassing the roof and floor of the left atrium, with a separate connection to the annulus of the mitral valve
- Isolation of known potential sources of fibrillatory stimuli
- Ligation of the left atrial appendage
Bilateral Pulmonary Vein Isolation
A wide ablation of the inlets of the pulmonary veins into the left atrium isolates the most common source of abnormal electrical stimuli which may trigger atrial fibrillation. However, since this ablation is performed using a bidirectional clamp, the treated tissue is safely in the left atrium itself, away from the delicate pulmonary veins. This feature eliminates the risk of pulmonary vein stenosis, while achieving a complete, durable electrical isolation of the entire pulmonary vein complex.
Mapping and Ablation of Epicardial Autonomics
The autonomic nervous system is a part of the central nervous system responsible for the unconscious regulation of numerous bodily processes, including temperature, thirst, sweating, and heart rate. Nerve fibers from the autonomic system enter the external surface of the heart in localized areas which are easily accessible to the total thoracoscopic maze. In many patients with atrial fibrillation, abnormal impulses from the epicardial autonomics produce a shortened refractoriness, or resting period between firings, in the atrial muscle. The result is a lowered threshold at which the atrium sustains fibrillation.
In the total thoracoscopic maze, all abnormal epicardial autonomics are located using a high-frequency stimulation probe. The probe elicits an immediate, temporary slowing of heart rate, providing safe, definitive identification of all abnormal nerve fibers. The abnormal autonomics are ablated until all positive testing signals are extinguished.
Extended Lesions on the Left Atrium Roof and Floor
Particularly in advanced atrial fibrillation, structural changes in the left atrium involving atrial stretch or fibrosis result in uneven conduction across the atrial muscle. This differential in the rates of conduction allows for the formation of random sites in the atrium capable of auto-triggering fibrillation. The key anatomy in the left atrium for perpetuating atrial fibrillation is the annulus of the mitral valve, which serves as the hub for the random, circular movement of fibrillatory current.
The total thoracoscopic maze addresses the left atrium specifically with separate connecting lesions between both the superior and the inferior pulmonary veins, corresponding to the roof and floor of the left atrium, respectively. Each of these lines joins with the pulmonary vein isolation boxes at either end. The result is complete electrical isolation of the posterior left atrium - a large area of the substrate supporting fibrillation - from the remainder of the heart.
Additionally, a separate connection is made between the mitral annulus and the left atrial roof line. The net effect is a complete interruption of macro re-entry in two perpendicular planes relative to the mitral annulus.
Isolation of Known Potential Sources of Fibrillatory Stimuli
This component involves isolation of the superior vena cava and the coronary sinus. These structures have been implicated as potential sources of ectopic stimuli capable of initiating atrial fibrillation. The superior vena cava is quickly isolated just above its junction with the right atrium using a bipolar clamp device. The coronary sinus is readily treated with a linear bipolar ablation device.
Ligation of the Left Atrial Appendage
The last component of the operation consists of closing the left atrial appendage. The purpose for this maneuver is to reduce the risk of stroke. 90% of the potentially stroke-causing clots found in the heart in association with atrial fibrillation are located in the left atrial appendage. The appendage is an otherwise useless structure which is quickly closed using an endoscopic stapler. Real-time echocardiography confirms complete ligation of the appendage.
Real-Time 'Four-Box' Verification of All Procedure Goals
As performed at The Ohio State University, the clear distinguishing feature of the total thoracoscopic maze over all other anti-atrial fibrillation procedures is verification of all technical components with the most rigorous standards - nothing is assumed concerning the effectiveness of any given maneuver.
Using a novel "four box" verification technique pioneered at The Ohio State University, electrical isolation of all potential sources of atrial fibrillation is confirmed in real time for each patient. Separate testing of the four electrical compartments enables immediate identification of areas for additional treatment in case a leak is detected. As a final test, at the end of the procedure, all patients are checked for spontaneous conversion to normal sinus rhythm after being placed into atrial fibrillation with high frequency stimulation of the untreated atrium. This non-inducibility of atrial fibrillation further confirms complete treatment of all sources of fibrillation in any given patient.
