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Flashcards in Heart Block Deck (14)
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How long is a normal QRS in seconds?

0.06-0.12 seconds


How long can a normal QT interval be?

0.44 seconds


What normally causes a heart block?

Abnormal conductance of the action potential at the AVN


What is a first degree heart block?

An extended PR interval of over 0.20, requires no treatment


Second degree mobitz type 1 heart block is?

Progressive prolongation of the PR interval culminating in a non-conducted P wave. Doesn't usually require any intervention either


Second degree mobitz type 2 heart block is?

Constant PR interval with intermittently non-conducted P waves and is caused by a conduction disorder in the bundle of Hiss. Always SINISTER and requires pacemaker


Third degree heart block is?

Complete AV node dissociation causing a ventricular escape rhythm at around 30BPM. Results in narrow QRS if from the bundle of Hiss and broad if it's originating in the ventricles. Requires pacemaker


What are bundle branch blocks

Abnormal conduction patterns causing the QRS to become longer than 0.12 as bundles conduct slowly and late


What does it mean for those reading the ECG of someone with a LBBB?

No interpretations can be made about the ST segment or T wave


Signs of RBBB

QRS >0.12 seconds and secondary R wave and slurred S wave. Results in M appearance in V1-3 and W appearance in V6


Signs of LBBB?

QRS >0.12 seconds M pattern in V5 and inverted T waves in leads I, aVL, V5-V6


Causes of RBBB

PE and pulmonary heart disease


Causes of LBBB

IHD, cardiomyopathy, idiopathic fibrosis


What is the normal length of a PR interval in seconds?

0.12-0.20 seconds