Ventricular Arrhythmias and Heart Blocks MCQs

Answer- A. Left ventricular hypertrophy Normally, QRS axis ranges from -30° to 90°C An axis more negative than -30° is referred to as left axis deviation and an axis more positive than +100° is called right axis deviation Left axis deviation Axis more negative than -30° Associated with Left ventricular hypertrophy Left anterior fascicular block Inferior M.I.

Asymptomatic patients with first- or second-degree Mobitz type I AV block do not require any specific therapy. Patients should undergo treatment of any potentially reversible cause (ie, myocardial ischemia or medication effect) Symptomatic patients with any degree of heart block should be treated urgently with atropine (initial dose 0.5 mg given intravenously) or temporary pacing (transcutaneous or transvenous). Indications for permanent pacing: Symptomatic Brady arrhythmias with any degree of AV block Asymptomatic high-degree AV block (second degree Mobitz type II or third- degree heart block) with slow ventricular rates (less than 40 beats/min). Patients with presumed cardiac syncope with normal heart rates and rhythm but bifascicular or trifascicular block on ECG Reference: Harrison's Principles of Internal Medicine 21 st edition Page 1883

A cardiac electrophysiological study would be necessary to help confirm whether this patient has inducible ventricular tachycardia, and ablation of the pathways if so. However in a young patient with no coronary artery disease demonstrable to revascularize, ICD is necessary to treat a possible further cardiac arrest. Reference: Harrison's Principles of Internal Medicine 21 st edition Page 1873

The patient is likely to have ventricular tachycardia in view of the very fast ventricular rate and broad complexes on ECG. Amiodarone is the preferred pharmacological agent for acute agent in VT without hemodynamic compromise. Verapamil is contraindicated in VT because it can cause the blood pressure to drop drastically due to negative inotropic action. Reference: Harrison's Principles of Internal Medicine 21 st edition Page 1922

The electrocardiogram waveforms are labelled alphabetically, beginning with the P wave, which represents atrial depolarization. PR interval shows the AV nodal delay to allow for the filling of ventricles The QRS complex represents ventricular depolarization, and the ST-T-U complex (STsegment, T wave, and U wave) represents ventricular repolarization. The J point is the junction between the end of the QRS complex and the beginning of the ST segment. Atrial Repolarization (STa and Ta) is usually too low in amplitude to be detected, but it may become apparent in conditions such as acute pericarditis and atrial infarction. Reference: Harrison's Principles of Internal Medicine 21 st edition Page 1866

Torsades de pointes is characterised by twisting pattern of ventricular tachycardia in ECG that occurs in the background of prolonged QT interval The drugs, metabolic abnormalities etc. that can prolong QTc can potentially lead to torsades de pointes. IV Magnesium sulphate given at a bolus dose of 1-2 gm is considered to be effective in this condition and is considered the treatment of choice Metoprolol and lignocaine may also be effective in some cases but are not the first line agents. Amiodarone is avoided in such patients as it can further prolong the QTc interval Reference: Harrison's Principles of Internal Medicine 21 st edition Page 1924

Metoprolol is a beta blocker. It causes bradycardia by acting on the β 1 receptor in the heart. Verapamil is a calcium channel blocker and is an AV nodal blocking agent . It causes bradycardia by blocking the AV node. In the sinoatrial and atrioventricular nodes, where depolarization is due primarily to a Ca2+-dependent slow inward current, the Verapamil slow the sinus pacemaker and inhibit atrioventricular conduction. So the combined effect will be bradycardia with AV blocks.

Answer is C (LBBB) Left Bundle Branch Block (LBBB) is typically associated with Reversed or Paradoxical Splitting of S2 Paradoxical splitting of second heart sound is caused by delayed A2 or early P2. Left Bundle Branch Block (LBBB) is associated with delayed Aortic closure (delayed A2) due to delayed electrical activation of the left ventricle. ASD and RBBB are associated with a wide physiological (non- paradoxical) split of second heart sound due to delayed pulmonic closure (Delayed P2) while VSD is associated with a wide physiological (non-paradoxical) split second heart sound from early aortic closure (Early A2).