amiodarone). The risk of AV block is remote (less than 1%) unless
the accessory pathway is located close to the AV node in which
case the risk is higher. In infants and young children, on the other
hand, it is often worth deferring RF ablation if possible because
there is a chance that ventricular pre-excitation may resolve over a
few years.
In contrast to the above, arrhythmias such as AV nodal re-
entrant tachycardia often respond to acute or interval therapy
with one of the more benign AV nodal blocking agents e.g.
digoxin, beta blockers or calcium blocker. RF ablation should
therefore be reserved for recurrent or troublesome arrhythmia.
Situations that justify earlier RF ablative therapy include haemo-
dynamic instability during episodes, intolerance of drugs, desire
to avoid long term drug therapy or occupational constraints such
as in airline pilots. It is also worth bearing in mind that once a
patient requires more than two drugs for prophylaxis, it becomes
more cost effective to proceed to RF ablation. The risk of AV block
during RF ablation for AV nodal re-entrant tachycardia is
between 1 and 2%,^2 and is dependent on the experience of the
operator. In the younger patients, even this low rate of compli-
cation can be important considering life time commitment to
cardiac pacing in the event of heart block.
The risk of RF ablation is primarily that of AV block as noted
above. Other risks are those related to cardiac catheterisation
and include vascular damage, cardiac tamponade, myocardial
infarction, cerebrovascular or pulmonary embolism and rarely
damage to the valve in left sided pathways. In experienced
centres, the risk of serious complications is less than 1%.
RReeffeerreenncceess
1 Ganz LI, Friedman PL. Medical progress: supraventricular tachycardia.
N Engl J Med1995; 333322 : 162–73.
2 Kay GN, Epstein AE, Dailey SM et al. Role of radiofrequency ablation
in the management of supraventricular arrhythmias: experience in 760
consecutive patients. J Cardiovasc Electrophysiol1993; 44 : 371–89.