Heart Blocks Flashcards
1
Q
What’s the Block?
A
1st Degree Heart Block
- PR interval > 0.20secs (5 small squares)
- Usually regular
- Usually benign
- No specific treatment required
2
Q
What’s the Block?
A
2nd Degree Heart Block Mobitz 1 (Wenckebach)
- PR interval extends until a P wave is not followed by a corresponding QRS complex
- Following PR interval is short/normal and the cycle starts again
- QRS complex must be seen at least twice in a row in order to see this pattern
- Usually benign, asymptomatic pt do not require treatment, permanent pacing rarely required
- Symptomatic pt usually respond to atropine
3
Q
What’s the Block?
A
2nd Degree Heart Block Mobitz 2
- Intermittently P waves are not followed by a QRS, with no real pattern
- P waves remain at a constant rate
- Whenever there is a QRS, the PR interval remains constant throughout
- Type 2 is of greater concern than Type 1 and sometimes requires pacing
- Extended RR interval will be an exact multiple of the number of dropped beats
- Likely to progress into bradycardia or 3rd degree block, can cause syncope and sudden cardiac death
- Immediate admission for cardiac monitoring and likely permanent pacing
4
Q
What’s the Block?
A
3rd Degree/Complete Heart Block
- No relationship between the P waves and the QRS complexes
- Usually more P waves than QRS complexes
- P & QRS are both regular but independantly of each other
- Ventricular response is usually bradycardic and the QRS are often wide and bizarre
- Typically pt will present as severe bradycardia with independant atrial/ventricular rates
- P likely to suffer ventricular standstill causing syncope or sudden cardiac death
- Urgent admission for cardiac monitoring, usually permanent pacing
5
Q
What’s the Block?
A
Left Bundle Branch Block (LBBB)
- Wide QRS with possible absence of Q in lateral leads
- Tall R waves Lateral I, V5-V6
- Deep S waves anterior V1-V3
- Broad ‘notched’ or ‘M’ shaped R wave in lateral leads
Traditionally LBBB accompanied by chest pain was criteria for thrombolysis
6
Q
What’s the Block?
A
Right Bundle Branch Block (RBBB)
- Broad QRS > 120 ms
- RSR’ pattern in the anterior leads V1-3 (‘M-shaped’ QRS complex)
- Wide, slurred S wave in the lateral leads (I, aVL, V5-6)
7
Q
What’s the Rhythm?
A
Bifascicular Block
RBBB
+
Left Axis Deviation
8
Q
What’s the Rhythm?
A
Trifascicular Block
RBBB
+
Left Axis Deviation
+
1st Degree Heart Block
May progress to 3rd degree/complete heart block then require permanent pacing
