25/03/2017
EKG Findings and Arrhythmias - USMLE Step 2 CK exam
EKG Findings and Arrhythmias – USMLE Step 2 CK exam BY PAUL CIURYSEK, MD /
TUESDAY, 08 JUNE 2010 /
PUBLISHED IN INTERNAL MEDICINE
EKG findings and Arrhythmias Heart Blocks: First-degree AV block – normal sinus rhythm with PR interval ³ 0.2ms Second-degree, type 1 (Weckenbach) block – PR interval elongates from beat to beat until a PR is dropped Second-degree, type 2 (Mobitz) block – PR interval fixed but there are regular non-conducted P-waves leading to dropped beats Third-degree block – no relationship between P waves and QRS complexes. Presents with junctional escape rhythms or ventricular escape rhythm
Atrial Fibrillation The most common chronic arrhythmia From ischemia, atrial dilatation, surgical history, pulmonary diseases, toxic syndromes https://www.usmlesuccess.net/ekg-findings-and-arrhythmias-usmle-step-2-ck-exam Classically, the pulse is irregularly irregular
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25/03/2017
EKG Findings and Arrhythmias - USMLE Step 2 CK exam
Signs and Symptoms: Chest discomfort Palpitations Tachycardia, Hypotension + syncope Treatment: Control rate with b-blockers, CCB’s, and digoxin (not acutely) If fibrillations last >24hr then should anticoagulate with warfarin for at least 3 weeks before cardioversion (prevents embolisms) If you cannot convert to normal sinus rhythm, the patient will require long-term anticoagulation. 1st line is warfarin, 2nd line is aspirin Cardioversion to convert to normal rhythm: 1st line – IV procainamide, sotalol, amiodarone Electrical à shock of 100-200J followed by 360J Atrial Flutter Less stable than Afib The rate is slower than that of atrial fibrillation (approximately 250-350bpm) Ventricular rate in atrial flutter is at risk of going too fast, thus atrial flutter is considered to be more dangerous (medically slowing this rate can cause a paradoxical increase in ventricular rates) Classic rhythm is an atrial flutter rate of 300bpm with a 2:1 block resulting in a ventricular rate of 150bpm Signs and symptoms similar to those of atrial fibrillation Complications include syncope, embolization, ischemia, heart failure Classic EKG finding is a “sawtooth” pattern:
Treatment: If patient is stable, slow the ventricular rate with CCB’s or b-blockers (avoid procainamide because it can result in increased ventricular rate as the atrial rate slows down) If cardioversion is going to take place be sure to anticoagulate for 3 weeks If patient is unstable must cardiovert à start at only 50J because is easier to convert to normal sinus rhythm than atrial fibrillation Multifocal Atrial Tachycardia (MFAT) An irregularly irregular rhythm where there are multiple concurrent pacemakers in the atria. Commonly found in pts with COPD EKG shows tachycardia with ³ 3 distinct P waves
https://www.usmlesuccess.net/ekg-findings-and-arrhythmias-usmle-step-2-ck-exam
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25/03/2017
EKG Findings and Arrhythmias - USMLE Step 2 CK exam
Treatment: Verapamil Treat any underlying condition Supraventricular Tachycardia Many tachyarrhythmias originating above the ventricle Pacemaker may be in atrium or AV junction, having multiple pacemakers active at any one time Differentiating from ventricular arrhythmia may be difficult if there is also the presence of a bundle branch block Treatment: Very dependent on etiology May need to correct electrolyte imbalance May need to correct ventricular rate [digoxin, CCB, b-blockers, adenosine (breaks 90% of SVT)] If unstable requires cardioversion Carotid massage if patient has paroxysmal SVT Ventricular Tachycardia VTach is defined as ³ 3 consecutive premature ventricular contractions If sustained, the tachycardic periods last a minimum of 30s. Sustained tachycardia requires immediate cardioversion due to risk of going into ventricular fibrillation
Treatment: If hypotensive or no pulse existent do emergency defibrillation (200, then 300, then 360J) If patient is asymptomatic and not hypotensive, the first line treatment is amiodarone or lidocaine because it can convert rhythm back to normal Ventricular Fibrillation Erratic ventricular rhythm is a fatal condition. Has no rhyme or rhythm
Signs and Symptoms: Syncope Severe hypotension Sudden death https://www.usmlesuccess.net/ekg-findings-and-arrhythmias-usmle-step-2-ck-exam
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