Correspondence-
Dr Debasis Acharya, Department of cardiology, All India Institute of
Medical Sciences. Bhubaneswar, Odisha, India 751019.
Email: debasisacharyabhu@gmail.com
Mob No- +917675992616
Keywords: Incessant, Repolarisation.
Disclosures: None
Funding: None
Conflict of interest: None
Case : 35 year female with structurally normal heart presented
with incessant long RP tachycardia (Fig-1). Interestingly the T wave
morphology and amplitude were changing with each alternate beat
suggestive of macro T wave alternans (TWA). Serum electrolytes
(Na+, K+,Ca++,
Mg++) were within normal limit. Electrophysiology
study revealed constant VA interval with same eccentric(earliest A
signal in CS7-8 pole) atrial activation pattern in all beats.
Tachycardia was confirmed to be orthodromic atrioventricular re-entrant
tachycardia through right posteroseptal pathway which was successfully
ablated.
Discussion : Macro T wave alternans or repolarisation alternans
is a rare electrical phenomenon. It suggests inhomogeneity in
refractoriness of the myocardium which cause unidirectional functional
block and re-entry resulting in malignant ventricular arrhythmias. It is
commonly seen in QT prolongation, electrolyte imbalance, acute
myocardial ischemia and in patients with severe left ventricular
systolic dysfunction. QRS alternans in orthodromic AVRT is a well known
entity but T wave alternans as described in our case is rare one to be
reported. Tomcsayni J et.al have reported a case of atrial tachycardia
with TWA which disappeared after termination of tachycardia.
Differential recovery of Ca++ channels in cardiac
myocytes in incessant AVRT may be the plausible explanation.
Figure Legends :
Fig-1 Narrow complex regular tachycardia showing T wave alternans.
Fig-2 Corresponding electrograms (EGM) also showing macro T wave
alternans (TWA) with same VA interval and atrial activation pattern
which suggests that there is no beat to beat variation of RP interval
and P wave morphology; thus confirming it T wave alternans.
Fig-3 Post ablation electrocardiogram showing no T wave alternans.