March/April - West Virginia State Medical Association

Scientific Article |
Table 1: Class I indications for ICD implantation in patients with structural heart disease. Adapted from ACC
Guidelines, 2008. 12
Class I ICD indications in patients with structural heart disease
1) In survivors of cardiac arrest due to VF or hemodynamically unstable VT after excluding any completely reversible
cause
2) With structural heart disease and spontaneous sustained VT
3) With syncope of undetermined origin with sustained VT or VF induced at EP study
4) With LVEF < 35% who are at least 40-days post MI or 3-months post intervention (PCI or CABG) and who are
NYHA CHF class II or III
5) With nonischemic dilated cardiomyopathy and LVEF < 35% and who are NYHA CHF class II or III
6) LVEF < 30 % who are at least 40-days post MI or 3-months post intervention (PCI or CABG) and who are NYHA
CHF class I
7) With non-sustained VT and prior MI, LVEF < 40%, and inducible VF or sustained VT at EP study
Figure 1.
3-dimensional electroanatomic map of left atrium with markers representing a typical
lesion set encircling the left and right pulmonary veins along with radiofrequency ablation
performed along the roof of the left atrium connecting the encircling lesion sets.
(ICD) technology has changed
the management of ventricular
arrhythmias (VA). Both primary
prevention (identifying and
prophylactically treating individuals
to prevent sudden cardiac death
(SCD) before an episode of
ventricular tachycardia (VT) or
ventricular fibrillation (VF) occurs)
and secondary prevention (treating
individuals who have suffered and
survived an episode of VT or VF)
has become common place in the
daily practice of cardiology and
electrophysiology. As medical and
device based treatment has improved,
survival of patients with more severe
heart disease and heart failure is
likewise improving. Practitioners
have to deal with VA almost on
a daily basis. It is important to
understand both the pathophysiology
and the treatment options available
to individuals with VA.
Ninety percent of patients with VA
have structural heart disease (SHD). 9
This is mostly scar-related reentry
occurring either at the border zone
of a scar from myocardial infarction,
or in areas of scar in nonischemic
dilated cardiomyopathy, or around
surgical scars. Reentry has either an
isthmus bounded by two scars or a
scar and a line of anatomic barrier
or physiologic conduction block. 10 In
general, most scar-based VT arises in
the left ventricle (LV). VTs with right
bundle branch block (RBBB) patterns
always arise in the LV, and VTs with
left bundle branch block patterns
almost always arise in or adjacent
to the LV septum. 11 The QRS axis is
critical to identifying the exit site of
the VT. A superior axis (negative in
inferior leads) suggests an inferior
wall exit site whereas an inferior axis
(positive in inferior leads) suggests an
anterior wall exit site. Scar-based VTs
typically have QRS duration greater
than 140 msec and the presence
of a Q-wave is often suggestive
of a scar-based mechanism.
Patients who present with
polymorphic VT or VF and ischemic
symptoms should be evaluated for
active myocardial ischemia. Patients
with sustained monomorphic VT
often have stable coronary artery
disease (CAD) with previous
myocardial infarction allowing for
scar-based reentry. The American
College of Cardiology has published
32 West Virginia Medical Journal