WBR0359
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| Author | Neeraja Danda M.B.B.S |
|---|---|
| Exam Type | USMLE Step 2 CK |
| Main Category | Internal medicine |
| Sub Category | Cardiovascular |
| Prompt | A 48 year old male presented to the emergency room with chest pain and diaphoresis . Electrocardiogram showed ST segment elevation in leads II, III, aVF. Angiogram revealed 75% stenosis in the right coronary artery and angioplasty was performed. While in the Intensive care unit the patient suddenly complains of dizziness , and dyspnea . Electrocardiogram on the monitor displays uncoordinated P waves and QRS complexes with an atrial rate of 90 beats per minute and ventricular rate of 45 beats per minute. What is the most likely diagnosis? |
| Answer A | Reinfarction |
| Answer A Explanation | incorrect Reinfarction would show new ST elevations or depressions on electrocardiogram. |
| Answer B | Sinus bradycardia |
| Answer B Explanation | Incorrect Sinus bradycardia refers to a heart rate less than 60 per minute with regular rhythm on electrocardiogram. |
| Answer C | Third degree atrioventricular block |
| Answer C Explanation | Uncoordinated firing of the atria and ventricles accompanied by dizziness, and dyspnea strongly suggest third degree heart block |
| Answer D | Multifocal atrial tachycardia |
| Answer D Explanation | Incorrect Multifocal atrial tachycardia is characterized by polymorphic P waves on electrocardiogram. |
| Answer E | Ventricular Tachycardia |
| Answer E Explanation | Incorrect Ventricular tachycardia is characterized by a wide QRS complex tachycardia on electrocardiogram |
| Right Answer | C |
| Explanation | Complications of myocardial infarction is a high-yield topic for USMLE exams. Sinus bradycardia, heart block, ventricular tachycardia, ventricular fibrillation, valvular or septal rupture and pericarditis are complications of myocardial infarction.Dizziness,dyspnea and an electrocardiogram showing uncoordinated P and QRS suggest third degree heart block.
Educational Objective: Uncoordinated firing of the atria and ventricles accompanied by dizziness, and dyspnea strongly suggest third degree heart block . References:Page 71, 551, 552, 553, 558 Master the boards Step 2 Ck second edition, Page 73 Master the boards Step 3 2009 edition. |
| Approved | Yes |
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