ECG Conduction Problems Flashcards
Second degree block
Mobitz type2 occasional no conducted beats Wenckeback progressive lengthening of the PR interval, then no conducted p wave, followed by repetition of cycle 2:1 or 3:1 block 2 or 3 p waves per QRS
Third degree complete block
No relationship between p wave and QRS Usually wide QRS complexes QRS rate less than 50 min Sometimes narrow QRS 50-60min
RBBB
QRS 120ms RSR pattern Usually dominant R1 wave in lead V1 Inverted T waves V1 sometimes V2 V3 Deep S wave lead V6
Left anterior hemiblock
Left axis div Deep S waves 2 and 3 Slightly wide QRS
LBBB
QRS greater than 120ms M pattern V6 sometimes in V4 -V5 No septal Q waves Inverted T waves 1,VL, V5,V6 sometimes V4
Common super ventricular rhythms
most commom SVT are caused by reentry phenomenon
Sinus rhythms
Atrial extra systole Junctional (AV nodal )
Atrial tachy
Atrial flutter
Junctional (AV nodal) tachy Junctional (AV nodal)
Atrial fibrillation
Rhythm abnormalities
Extra systole single early beats suppressing the next sinus beat Escape beat absence of sinus beat followed by late single beat Tachy Brady
Common ventricular rhythms
Ventricular extra systole
Accelerated idioventricular rhythm
Ventricular escape single beats or complete heart block Ventricular fibrillation
Myocardial infarction Sequence of ECG change
1 normal ECG
2 raised ST segment
3 Appearance of Q waves
4 normalisation of ST segment
5 inversion of 5 waves
Site of infarction Anterior infarction changes classically in leads
V3 V4 but often seen V2 And V5
Site of Inferior infarction changes in leads
3 and VF
Lateral infarction changes in leads
1, VL, V5 and V6
true posterior infarction dominant R wave in lead V1
Pulmonary Embolism Possible patterns
Normal ECG with sinus tachy
Peaked P waves
RAD RBBB
Dominant R waves V1
Inverted T waves in leads V1 V3
Deep S waves in V6
S waves in 1 Q and inverted T waves in 3
Right ventricular hypertrophy
RAD
Tall R waves lead 1
T wave inversion in lead V1 V2 sometime V3 and even V4
Deep S wave in V6
Sometimes RBBB
Left ventricular hypertrophy
R waves in lead V5 or V6 greater than 25 mm
S waves in lead V1 or V2 greater than 35mm
Inverted T waves in leads 1, VL, V5 V6 sometimes V4
Left atrial hypertrophy How would the P waves look
Bifid P waves
Right atrial hypertrophy How would the P waves look
Peaked P waves
P QRS apparently not 1 to 1 consider what
1 P wave is actually present but not easily seen try
2 V1 2 QRS is irregular the rhythm is probably atrial fib and what seem to be p waves or not
3 if the QRS rate is rapid and no P waves a wide QRS indicates ventricular tachy and narrow QRS indicates junctional (AV nodal) tachy If QRS is rate is slow, it’s probably an escape rhythm
P QRS more than 1 to 1 Consider what
If P wave rate >300min is atrial flutter
If P wave rate 150-200 min two P waves per QRS atrial tachy with block
If the P wave rate is normal 60-100min 2 to 1 SR second degree block
PR interval appears to be different with each beat third degree block
Wide QRS greater than 120ms
SR
BBB
WPW
Ventricular extra systole
Ventricular tachycardia
Complete heart block
Q waves normal left to right depolarisation interventricular septum
Small (septal) Q waves normal seen in leads 1 VL andV5 V6
Q waves in 3 and avr is normal variant
Q waves in more than one lead longer than 40ms and deeper 2mm indicate infarction
Q waves indicate site of infarction
under normal circumstances q waves should been seen in right side leads v1_v3
ST segment depression
Digoxin: ST slopes downwards depression Ischaemia: ST flat segment depression
T wave inversion
normal t wave amplitude limb / precordial
Normal in leads VR V1 and V2 and V3 in black people Ventricular rhythms BBB Mi Right and left ventricular hypertrophy WPW
less than 5mm limb
Less than 15mm precordial
First degree block
One P wave per QRS PR interval greater than 200ms
