Heart block and other conduction failures Flashcards
First Degree
PR interval > 5 little boxesA
All P waves followed by QRS
Often asymptomatic
Delayed AV node transmission
Type 1 Second Degree
PR interval gets longer until QRS wave fails to follow P wave
Likely cause AV node damage
Type 2 Second Degree
Some P waves blocked and not followed by QRS
PR interval remains the same
Problem in Bundle of His
Treatment: implant pacemaker
Third Degree
Atrial signals consistently fail to arrive at ventricles Consistent ventricular rate 30-40 bmp PR interval varies radically Intrinsic Ventricular rate (<60 bpm) Atrial beats consistent
Escape Beats
Late
Triggered by natural rhythmicity of non-atrial tissue
Occur when atrial signal is delayed
Premature Beats
Early
Due to irritable tissue
Triggered often in ventricular tissue or by AV node - ectopic beats
Atrial Fibrillation
Disorganised electrical activity in atria
No P wave - flat wiggly line instead
Fast and irregular ventricular rate - Many signals reach AV node
Common in elderly
Stroke risk - can lead to thrombus formation
ST segment Elevation
Interval = duration from start of x to end of y
Segment = from end of x to start of y
ST segment - end of QRS to start of T - elevation = sign of acute MI
Isoelectric baseline - end of T to next P
Premature ventricular contraction
Unusually wide, weird-looking ventricular electrical activity
No S wave - instead a wide negative dip where T wave should be
Often beat triggered in middle of myocardium - ventricles electrically unsynchronised
Delayed inefficient conduction
Respiratory Sinus Arrythmia
Heart beat faster on inspiration than expiration
Children and athletes
Observe ventricular rate - inverse of RR interval