Surgery for Atrial Fibrillation

AORN Journal,  July, 2007  by Patricia C. Seifert,  Jill Collins,  Niv Ad

• E-mail
• Print
• Link

PREVENTION OF THROMBOEMBOLISM. The Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) (19) study demonstrated no advantage of rhythm control over rate control in asymptomatic patients. These results have encouraged the use of rate control with anticoagulation to reduce the incidence of intracavity clot formation as an acceptable therapy for patients who have a rate-controllable disorder that can be made asymptomatic by this treatment regimen. For patients who do not benefit from a rate-control strategy, rhythm control or nonpharmacologic treatments are implemented. Unfortunately, the strategy of rate control with anticoagulation does not reduce the potential ill effects of AF (ie, stasis of blood) and is unsuitable in patients for whom anticoagulation is contraindicated (eg, individuals with bleeding disorders).

ADDITIONAL THERAPIES. Additional therapies include antihypertensive medications to reduce intracardiac and intrapulmonary blood pressures. Supplemental electrolytes may be ordered to stabilize existing electrolyte imbalances in the heart. (1)

NONPHARMACOLOGIC THERAPY

When pharmacologic intervention is unsuccessful in treating AF, nonpharmacologic therapy is instituted. Treatments include synchronized cardioversion to electrically shock the fibrillating atrium back to normal sinus rhythm, percutaneous catheter-based interventional ablative techniques, and surgery.

CARDIOVERSION. Cardioversion is an electrical shock administered to the patient in an attempt to restore normal sinus rhythm. Cardioversion differs from defibrillation in that the former is an electrical shock synchronized to the R wave in the patient's ECG. In other words, there is a ventricular R wave and some form of conduction pattern. Defibrillation, on the other hand, employs electrical energy to shock a fibrillating ventricle that has no regular ventricular electrical pattern in order to regain a functional rhythm. The patient must be adequately anticoagulated during cardioversion so the electrical shock does not disrupt a pre-existing intracardiac thrombus, causing it to embolize to the brain or other portion of the systemic circulation. (4)

CATHETER-BASED ABLATION TECHNIQUES. Catheter-based ablation techniques, which are performed in the electrophysiology (EP) laboratory or catheter-based interventional suite if there is no dedicated EP laboratory, initially were developed as a result of Cox's pioneering work with the Maze procedure. (20) These techniques also have been influenced by research demonstrating ectopic foci surrounding the pulmonary veins. Three-dimensional mapping/ imaging systems have been valuable for better defining the anatomy, thereby improving the precision of ablation techniques. (21)

After the patient is heparinized, the electrophysiologist percutaneously inserts a catheter into the femoral vein and threads it to the right atrium. The electrophysiologist accesses the left atrium via an interatrial septal puncture and creates lesions around the pulmonary veins using cryoenergy or radio-frequency (RF) energy. Newer energy sources include lasers, microwaves, and ultrasound (Table 4). Interventional techniques have shown better success in treating patients with paroxysmal AF compared to those individuals with an enlarged left atrium and persistent or permanent AF. (18) Complications include pulmonary vein stenosis, cerebrovascular accident, and cardiac tamponade. (20)