Heart Blocks and Heart failure Flashcards
What causes an upward deflection on the recording of an ECG?
Net current towards the electrode
PR interval normal length
0.12-.2 seconds
QRS complex normal length
0.8-0.1seconds
QT interval normal length?
0.4-0.43 seconds
ST interval normal length
0.32 seconds
What could a high amplitude of the P wave be caused by?
Atrial hypertrophy
When might the T wave be inverted?
Mobitz 1
What causes a longer ST interval?
Mobitz 1
What are the heart rates at tachycardia, flutter and fibrillation?
150-200, 200-300, 300
First degree heart block caused by?
Blockage between SA and AV node so slows conduction
What does first degree heart block show on an ECG?
Prolonged PR interval
What does Mobitz 1 show on an ECG?
progressive prolongation of the PR interval culminating in a non-conducted P wave thus the QRS complex is not evoked. PR interval is longest immediately before dropped beat
What does Mobitz 2 show on an ECG?
Intermittent non- conducted P waves- RR interval surrounding P wave is always a multiple
What is Mobitz 1 caused by?
Progressive fatigue of AV nodal cells
What is Mobitz 2 caused by?
Failure of Bundle of His to conduct. Likely to be due to structural damage, patients already have left bundle branch block and 2nd degree AV block is produced by intermittent failure of the remaining fasicles
What does 3rd degree heart block show on an ECG?
Complete dissociation of P wave and QRS complex
What are the symptoms of 3rd degree heart block?
Severe bradycardia with independent atrial and ventricular rates
What are the consequences of 3rd degree heart block?
Chamber contractions ou to sync, so atrial contact against closed tricuspid result in cannon wave where the blood goes back into jugular vein and the external jugular vein can be seen pulsing
What are symptoms of atrial fibrillation?
Usually asymptomatic but sometimes gives congestive symptoms
Treatment for atrial fibrillation
Flecanide, B blockers, Amodarone, Dronedarone
Why does atrial fibrillation need to be treated?
As blood pools develop in atria- clots form- mural thrombosis
Circus movements of heart?
electrical signal doesn’t complete its circuit but takes an alternative one due to the tissue being in abnormal non-refractory state
What causes non-refractory state?
Unidirectional block and transient bidirectional block
