12 Lead Mastery
Regular narrow complex tachycardia at about 150; flutter waves are best seen in inferior leads and V1; and may be hidden in the QRS
What is atrial flutter with 2 to 1 AV conduction
This structure normally initiates the heartbeat; its intrinsic rate is about 60 to 100
What is the SA node
The pathophysiologic driver of angina is mismatch between oxygen supply and demand causing this
What is myocardial ischemia
First line medication for symptomatic bradycardia when no contraindication; it blocks vagal tone at the SA and AV nodes
What is atropine
Cardiac output = heart rate x this variable
What is stroke volume
ST elevation in leads II, III, and aVF with reciprocal ST depression in I and aVL
What is an inferior STEMI
This phase of the ventricular action potential is driven mainly by calcium influx and is the target for nondihydropyridine calcium channel blockers
What is phase 2; the plateau
In right ventricular infarction; preload dependence makes this medication class risky if hypotension is present
What are nitrates
For torsades de pointes; this medication is first line even if magnesium level is normal
What is magnesium sulfate
Beck triad is classically associated with this cause of obstructive shock
What is cardiac tamponade
ST elevation in V1 through V4 with reciprocal ST depression in II, III, and aVF
What is an anteroseptal STEMI from LAD occlusion
This interval represents ventricular depolarization plus repolarization; prolongation increases risk for torsades
What is the QT interval
This coronary artery most commonly causes inferior wall MI
What is the right coronary artery
In cardiogenic pulmonary edema with hypertension; this medication reduces preload and afterload by venodilation at low doses
What is nitroglycerin
In massive pulmonary embolism causing obstructive shock; the primary failing chamber is typically this one first
What is the right ventricle
Diffuse ST depression in multiple leads with ST elevation in aVR; especially when paired with hypotension or ongoing chest pain
What is left main or proximal LAD ischemia; or severe multivessel ischemia
This bundle branch block pattern shows RSR prime in V1 with a wide terminal S in leads I and V6
What is right bundle branch block
ST elevation in V1 to V4 with possible reciprocal inferior changes suggests occlusion in this artery territory
What is the LAD; anterior wall infarct
In pre-excited atrial fibrillation; avoid AV nodal blockers because they can accelerate conduction through accessory pathway; name one AV nodal blocker class to avoid
What are calcium channel blockers
In cardiogenic shock; lung findings and hemodynamics often include this; elevated left sided filling pressure and pulmonary edema
What is elevated Pulmonary Capillary Wedge Pressure; pulmonary congestion
Horizontal ST depression in V1 to V3 with tall R waves and upright T waves; often with posterior pain pattern; and improved with V7 to V9 placement
What is a posterior myocardial infarction; posterior STEMI equivalent
In WPW; the accessory pathway bypasses the AV node; this produces this ECG feature in sinus rhythm
What is a delta wave; with short PR interval and widened QRS
Papillary muscle rupture after MI can cause sudden pulmonary edema because it produces this acute valve problem
What is acute mitral regurgitation
This antiarrhythmic is preferred for stable wide complex tachycardia due to sodium channel blockade and is specifically useful in AF with WPW when available by protocol
What is procainamide
A post MI patient becomes acutely dyspneic with frothy sputum; has new loud holosystolic murmur; hypotension; and rapidly worsening pulmonary edema; explain the most likely mechanical complication and the immediate hemodynamic priority in one phrase
What is papillary muscle rupture causing acute severe mitral regurgitation; prioritize afterload reduction and forward flow support while preparing for definitive surgical management