Medical Care: Most of the patients who present with PSVT have AVNRT or AVRT. These arrhythmias depend on AV nodal conduction and therefore can be terminated by transiently blocking AV nodal conduction.
Vagal maneuvers are the first-line treatment in hemodynamically stable patients. Vagal maneuvers, such as breath-holding and the Valsalva maneuver (ie, having the patient bear down as though having a bowel movement), all slow conduction in the AV node and can potentially interrupt the reentrant circuit.
Carotid massage is another vagal maneuver that can slow AV nodal conduction. Massage the carotid sinus for several seconds on the nondominant cerebral hemisphere side. This maneuver is usually reserved for young patients. Due to the risk of stroke from emboli, auscultate for bruits before attempting this maneuver. Do not perform carotid massage on both sides. A Valsalva maneuver, if performed properly by the patient, can frequently avert an attack.
Synchronized cardioversion starting at 50 J can be used immediately in patients who are hypotensive, have pulmonary edema, have chest pain with ischemia, or are otherwise unstable.
" Short-term medical management
o When SVT is not terminated by vagal maneuvers, short-term management involves intravenous adenosine or calcium channel blockers. Adenosine is a short-acting drug that blocks AV node conduction; it terminates 90% of tachycardias due to AVNRT or AVRT (Pieper, 1995; Campbell, 1997; Connors, 1997; Etheridge, 1999; Trohman, 2000). Adenosine does not usually terminate atrial tachycardia, although it is effective for terminating SNRT (Pieper, 1995; Campbell, 1997; Connors, 1997; Gold, 1999; Trohman, 2000). Typical adverse effects of adenosine include flushing, chest pain, and dizziness. These effects are temporary because adenosine has a very short half-life of 10-20 seconds (Siberry, 2000).
o Other alternatives for the acute treatment of SVT include calcium channel blockers like verapamil, diltiazem or beta-blockers like metoprolol or esmolol. Verapamil is a calcium channel blocker that also has AV blocking properties. Verapamil has a longer half-life than adenosine and may help maintain sinus rhythm following the termination of SVT. It is also advantageous for controlling the ventricular rate in patients with atrial tachyarrhythmia (Ganz, 1995; Campbell, 1997; Connors, 1997; Levy, 1997; Xie, 1998; Gold, 1999; Siberry, 2000; Josephson, 2001).
o Acute management of a wide complex tachycardia in a hemodynamically unstable patient requires immediate cardioversion whereas in a stable patient, IV procainamide, sotalol, or amiodarone is acceptable. Amiodarone is preferred in patients with impaired left ventricular function or in patients with heart failure (Blomstrom-Lundqvist, 2003).
o Treatment of AF and atrial flutter involves controlling the ventricular rate, restoring the sinus rhythm, and preventing embolic complications. The ventricular rate is controlled with calcium channel blockers, digoxin, amiodarone, and beta-blockers. The sinus rhythm may be restored with either pharmacological agents or electrical cardioversion. Pharmacological agents such as ibutilide convert AF and atrial flutter of short duration to sinus rhythm in approximately 30% and 60% of patients, respectively.
o Electrical cardioversion is the most effective method for restoring sinus rhythm. If AF has been present for longer than 24-48 hours, defer cardioversion until the patient has been adequately anticoagulated to prevent thromboembolic complications (Pieper, 1995; Campbell, 1997; Connors, 1997; Levy, 1997; Reimold, 1997; Gold, 1999; Siberry, 2000; Trohman, 2000).
" Long-term medical management
o The choice of long-term therapy for patients with SVT depends on the type of tachyarrhythmia and the frequency and duration of episodes, symptoms, and risks associated with the arrhythmia (eg, heart failure, sudden death). Evaluate patients on an individual basis, and tailor the best therapy for the specific tachyarrhythmia.
o Patients with PSVT may initially be treated with calcium channel blockers, digoxin, and/or beta-blockers. Class IA, IC, or III antiarrhythmic agents are used less frequently because of the success of radiofrequency catheter ablation (Pieper, 1995; Campbell, 1997; Connors, 1997; Levy, 1997; Reimold, 1997; Gold, 1999; Siberry, 2000; Trohman, 2000). Consider radiofrequency ablation for any patient with symptomatic PSVT in whom long-term medical treatment is not effectively tolerated or desired. In addition, because of the risk of sudden cardiac death, perform catheter ablation on patients with symptomatic WPW syndrome. Radiofrequency catheter ablation is more than 90% effective in curing PSVT (Ganz, 1995; Pieper, 1995; Xie, 1998; Trohman, 2000; Ganz, 2002).
o Radiofrequency ablation involves focally ablating the crucial component of the arrhythmia mechanism. For example, in AVNRT, the slow pathway is ablated, which prevents the reentry cycle. The accessory pathway is targeted in patients with AVRT. Focal atrial tachycardia, atrial flutter, and, in some cases, AF can also be cured with ablation. Radiofrequency ablation has a high success rate and is performed using conscious sedation in an outpatient setting or with overnight hospitalization. Complications, which occur at a rate of 1-3%, include deep vein thrombosis, systemic embolism, infection, cardiac tamponade, and hemorrhage. The risk of death is approximately 0.1%. The lifetime risk of fatal malignancy as a result of radiation exposure is low.
o Radiofrequency ablation is cost-effective for patients who have frequent episodes of SVT that require antiarrhythmic agents and frequent emergency visits. It is also indicated for patients with incessant tachycardia and for patients with symptomatic WPW syndrome. The optimal management strategy for patients with asymptomatic preexcitation syndromes remains uncertain (Scheinman, 1992; Strickberger, 1993; Lesh, 1994; Ganz, 1995; Ganz, 2002).
Surgical Care: Prior to the advent of percutaneous radiofrequency catheter ablation, open cardiac surgical procedures were the only means of curing PSVT. Currently, open surgical procedures are rarely performed.
Diet:
" Dietary changes depend on underlying medical problems.
Activity:
" Changes in physical activity depend on underlying cardiac problems and other comorbidities.
DRUG TREATMENT :
1. ANTIARRHYTHMICS :
- ADENOSINE - FIRST LINE MEDICAL TREATMENT
2. CALCIUM CHANNEL BLOCKERS ( NONDIHYDROPYRIDINE ) :
- VERAPAMIL
- DILTIAZEM
3. BETA BLOCKERS :
- PROPRANOLOL
- ESMOLOL
4. CARDIAC GLYCOSIDES :
- DIGOXIN