Indira 70/ F Retd. Matron GSH came with chief complains of Fever since 20-25 days Intermittent ,high grade asso. with chills n rigors Taking some oral medication from pvt. K/c/o SHT and DM since 15 yrs on Rx. 2 days later she had a cardiac arrest with the following ECG pattern
ECG findings :- Heart Rate – 50 bpm Regular Sinus rhythm Normal Axis P wave - normal PR interval - 0.12 sec QRS complex – normal width and shape QT interval – 0.56 sec QTc interval - 0.509 sec T wave – normal Impression :- Bradycardia with acquired prolonged QT syndrome Pt. was shifted to ICCU.
She developed cardiac arrest . Pulse – not felt BP - not recordable ECG showed Vent. Tachycardia 200 J Biphasic DC shock was given and was reverted to sinus rhythm
A Temporary Cardiac Pacemaker was inserted following Rt. Femoral Vein Catheterization and she was reverted to sinus rhythm over the next 2 days
QT interval : beginning of Q-wave upto the end of T-wave. QT interval : total duration of ventricular activity. Need for QTc Interval : The QT interval varies with RR interval. False high values may be noted in Bradycardias. LONG QT SYNDROME
Formula accepted for QTc is: BAZETT’s Formula : QTc = QT ∕√ (RR) A useful rule of thumb is that, with a normal heart rate ( 60 - 100 bpm), the QT interval SHOULD NOT exceed half the RR interval.
LONG QT SYNDROME CONGENITAL ACQUIRED Due to Genetic defects in K+ channels involved during repolarization. Severe form Includes: 1. Jervell Lange Syndrome (deafness, syncopal attacks , sudden death ) 2. Romano Ward Syndrome (similar to Jervell Lange syndrome but without deafness )
Congenital LONG QT SYNDROME LQT1 Gene Most common type QT interval fails to shorten post exercise T wave is broad and occupies majority QT interval Most common triggers: exercise, emotional stress. 80% have first presentation < 20 yrs Jervell Lange syndrome and Romano Ward syndrome are severe forms. LQT2 Gene T wave tends to be bifid and notched Additional Triger factors are sleep, auditory stimulation Respond to B-Blockers LQT3 Gene Poorest prognosis amongst all T wave is asymmetrical or Late biphasic Trigger factor : Bradycardia ( sleep ) B-Blockers Contraindicated Exercise is not Restricted
Complications OF Long qt syndrome Torsades des pointes ( polymorphic ventricular tachycardia ) More commonly seen in women Manifestation of subclinical LQTS Potentiated by bradycardia and hypokalemia drug usually blocks Ikr channel triggered by early afterdepolarizations due to intracellular Ca+ accumulation from a prolonged actin potential plateau heterogenicity of myocardial repolarisation predisposes to polymorphic ventricular activity
Treatment Caution has to be exercised during administering multiple drug regimes. They may cause QT Prolongation and TDP. Correction of K+ and Mg++ levels Temporary Pacing Cautious Infusion of Isoprotenol Class 1B anti arrythmics(no QT prolongation seen)