ECG Flashcards
Describe sinus tachycardia on ECG.
All QRS complexes are preceded by a normal p wave with a normal PR interval. HR >100. all impulses are initiated in the sinoatrial node.
Describe sinus bradycardia on ECG.
Sinus rhythm at a rate of <60bpm.
Causes for sinus bradycardia. (7)
Physical fitness. Vasovagal syncope, sinus node dysfunction, drugs (b-blockers, digoxin, amiodarone, non-dihydropyridine, CCBs), hypothyroidism, hypothermia, ^ICP.
Common causes for atrial fibrillation. (6)
Ischaemic heart disease, thyrotoxicosis, hypertension, obesity, heart failure, alcohol.
Heart block→ definition
Disrupted passage of electrical impulse through the AV node or his-purkinje system.
Causes of 1st and 2nd degree heart block.
Normal variant, athleticism, sinus node dysfunction. Ischaemic heart disease (especially inferior MI), acute myocarditis, drugs (digoxin, b-blockers).
Describe first degree heart block on ECG.
Delayed AV conduction. The PR interval is prolonged and unchanging; no missed beats.
Describe second degree: Mobitz I (Wenckebach) heart block.
Intermittent block within the AV node. The PR interval progressively lengthens until a QRS complex is missed. The pattern then resets.
Describe second degree: mobitz II heard block.
Dysfunction of the his-purkinje pathway. The PR interval of the conducted beats is constant until one or more p waves is not followed by a QRS complex. This rhythm is dangerous as it may progress to complete heart block.
Describe third degree heart block.
No impulses are passed rom the atria to the ventricles, so p waves and QRS complexes appear independently of each other. As tissue distal to the AV node paces slowly, the patient becomes very bradycardia and may develop haemodynamic compromise.
Causes of complete heart block. (7)
Ischaemic heart disease (especially inferior MIs, idiopathic (fibrosis), congenital, infective endocarditis, cardiac surgery/ trauma, digoxin toxicity,
Infiltration (abscesses, granulomas, tumours, parasites).
Describe the right ventricular strain pattern seen with pulmonary embolism.
R axis deviation
Dominant r wave
T wave inversion/st depression in V, + V2
Describe the rare S1Q3T3 pattern seen in pulmonary embolism.
Deep S waves in I
pathological Q waves in iii
Inverted T waves in iii
What heart territory is represented by leads I, aVL, V4-V6.
Lateral, circumflex artery
What heart territory is represented by vi-v3?
Anteroseptal, left anterior descending artery.
What heart territory is represented by leads II, iii, aVF?
Inferior, right coronary artery in 80%, circumflex in 20% “left dominant”.
What heart territory is represented by leads V7-V9?
Posterior, circumflex artery
When would you consider moving leads v4 -V6 to under the left scapula?
If ST depression in vi-v3 or R/S amplitude ratio in v1 Or V2 is >1. To detect posterior infarcts.
