Flashcards in Heart Block Deck (14):
How long is a normal QRS in seconds?
How long can a normal QT interval be?
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