Heart Block Flashcards
Extra systole
1) record the normal hr
2) connect first electrode around hook and connect second electrode around ventricle
3) two electrodes must not touch each other
4) stimulate heart first time during systole and second time during diastole
Results
Effect of stimulus while heart in systole: no effect & heart is in arp
Effect of stimulus while heart in diastole:
Extrasystole followed by compensatory pause then stronger contraction than normal
the heart in relative refractory period
Mention causes of extrasystole in humans (risk factors)
Alcohol, nicotine, caffeine.
Anxiety/ heart condition.
more strain during physical activities/ high blood pressure
What is the cause of compensatory pause that follows an extra systole beat then stronger contraction
The normal Sinus P wave isn’t able to reach the ventricles because
the ventricles in the refractory period of the 2nd stimulus prolongs the diastole time and ventricular filling
resulting
in a stronger contraction
Heart block Steps
Record heart rate
Put loop of thread around atrioventricular junction (gradual tighten)
Record heart rate
Note decrease in heart rate till stop, then appearance of idioventricular rhythm
Release the ligature and record the recover
First degree block
Prolonged interval between atrial and
ventricular contraction
Second degree block
Some impulses fail to reach ventricles and ratio of ataxia to ventricular beats is 2:1 3:1 5:1 and 8:1
Third-degree block
Complete heart block
All impulses fail to pass through an node to bundle
Ventricles may contact by its own independent idoventricular rhythm
What is stokes Adam syndrome
Sudden, brief loss of consciousness due to marked drop in CO with complete heart block
What is Wenckebach phenomenon
Progressive lengthening of conduction time, followed by a non-conducted impulse, or dropped beat
