PROLONGED QT INTERVAL The QT interval is the time from the start of the Q wave to the end of the T wave. It represents the time taken for ventricular depolarisation and repolarisation, effectively the period of ventricular systole from ventricular isovolumetric contraction to isovolumetric relaxation The QT interval is inversely proportional to heart rate: The QT shortens at faster heart rates The QT lengthens at slower heart rates An abnormally prolonged QT is associated with an increased risk of ventricular arrhythmias, especially Torsades de Pointes. The recently described congenital short QT syndrome has been found to be associated with an increased risk of paroxysmal atrial and ventricular fibrillation and sudden cardiac death How to measure QT The QT interval should be measured in either lead II or V5-6 Several successive beats should be measured, with the maximum interval taken Large U waves (> 1mm) that are fused to the T wave should be included in the measurement Smaller U waves and those that are separate from the T wave should be excluded The maximum slope intercept method is used to define the end of the T wave (see below) Corrected QT The corrected QT interval (QTc) estimates the QT interval at a heart rate of 60 bpm. There are multiple formulas used to estimate QTc (see below). It is not clear which formula is the most useful. Bazett’s formula: QTC = QT / √ RR Fredericia’s formula: QTC = QT / RR 1/3 Framingham formula: QTC = QT + 0.154 (1 – RR) Hodges formula: QTC = QT + 1.75 (heart rate – 60) Prolonged QT QTc is prolonged if > 440ms in men or > 460ms in women QTc > 500 is associated with increased risk of torsades de pointes QTc is abnormally short if < 350ms A useful rule of thumb is that a normal QT is less than half the preceding RR interval Causes of a prolonged QTc (>440ms) Hypokalaemia Hypomagnesaemia Hypocalcaemia Hypothermia Myocardial ischemia Post-cardiac arrest Raised intracranial pressure Congenital long QT syndrome DRUGS

male aged 35yrs presented with complain of dizziness ,on antihypertensive his BP is 130/80 his ecg and cxr are attached please comment

26 year old lady presented with sudden unconsciousness while eating followed by full recovery. She has no known disease for which she needs to be on medications. No history of premature death in family member. What is the diagnosis?

70 yrs old male pt admitted for acute retention of urine. .His ecg attached. . plz discuss about the ecg findings. ..and treatment for CAD in this pt..

A young female patient with previous cardiac arrest and a secondary prevention ICD attended following episodes of syncope. She had recently given birth to a healthy baby (<2 weeks previously). Here is the ECG strip from the ambulance service and the device interrogation from her ICD. What is the mechanism for this arrhythmia and the possible causes ?