ECG REVISION Flashcards
Sinus Rythm - normal characteristics
- HR : 50-100 BEATS/MIN
- P wave precedes every QRS complex
- P wave is positive in lead II
- PR interval is constant
Causes of bradycardia
1.Sinus bradycardia
2.SA Block
3.Sinoatrial arrest / inhibition
4.2nd Degree AV block
5.3rd Degree AV block
Escape rythm may arise during bradycardia
Bradycardia due to dysfunction in SA node is referred to as sinus node dysfunction (SND)
Causes of tachycardia ( tachyarrythmia ) with narrow QRS complexes ( QRS duration <0,12s )
- Sinus tachycardia
- Inappropriate sinus tachycardia
- SA re-entry tachycardia
- Atrial fibrillation
- Atrial flutter
- Atrial tachycardia
- Multifocal atrial tachycardia
- AVNRT ,AVRT ( pre- excitation ,WPW )
Causes of tachycardia ( tachyarrythmias ) with wide QRS complexes ( QRS duration >= 12 s)
1.Ventricular tachycardia ( the most common cause )
In which leads P wave is always positive ?
II, III , aVF
P mitrale
Increased P wave duration , enchanced second humpin lead II and enhanched negative deflection in V1
P pulmonale
Increased P wave amplitudes in lead II and V1
PR INTERVAL > 0.22 s
1st degree AV block
PR interval < 0.12 s
Pre - excitation ( WPW syndrome )
2nd degree AV - block Mobitz type I ( Wenckebach block )
Repeated cycles of gradually increasing PR interval until an atrial impulse ( P wave ) is blocked in the AV node + QRS does not appear
2nd degree AV - block Mobitz type II
Intermittently blocked atrial impulses ( no QRS seen after P ) but PR = Constant
3rd degree AV - block
All atrial impulses ( P waves ) are blocked by the AV node .
An escape rythm arises ( cardiac arrest ensues otherwise ) which may have narrow or wide QRS complexes , depending on its origin
QRS duration must be less than ?
< 0.12 s
High voltage example
S wave V1 or V2 + R wave V5 > 35 mm
Pathological Q waves >= ?
> = 0.03s
Amplitude >= 25% of R wave amplitude in the same lead , in at least 2 anatomically contiguous leads
Wide QRS complex ( ORS duration > 0.12s )
- Left Bundle Branch Block
- Right Bundle Branch Block
- Hyperkalemia
- Class I antiarrythmics
- Trucyclic Antidepressants
- Ventricular Rythm + ventricular extrasystoles ( premature complexes )
- Artificial pacemaker which stimulates in the ventricle
- Abberant conduction ( Abberancy )
- Pre - excitation ( WPW syndrome )
High voltage
- Hypertrophy
- LBBB ( leads V5 ,V6 , I , avL )
- RBBB ( V1 - V3 )
Low voltage
- Normal variant. Misplaced lead
- Cardiomyopathy
- COPD
- Perimyocarditis
- Hypothyreosis ( typically accompanied by bradycardia)
- Pneumothorax
- Extensive myocardial infarction
- Obesity
- Pericardial effusion
- Pleural effusion
- Amyloidosis
Pathological Q waves
- MI
- Left - sided pneumothorax
- Dextrocardia
- Perimyocarditis
- Cardiomyopathy
- Amyloidosis
- Bundle Branch blocks
- Anterior Fascicular Block
- Pre- excitation
- Ventricular hypertrophy
- Acute cor pulmonare
- Myxoma
Abnormal R - wave progression
- MI
- Right ventricular hypertrophy ( reversed R wave progression )
- Left ventricular hypertrophy ( amplified Rwave progression )
- Cardiomyopathy
- Chronic cor pulmonale
- LBBB
- Pre - excitation
Right axis deviation
- Right ventricular hypertrophy
- Acute cor pulmonale ( COPD , pulmonary hypertension , pulmonary valve stenosis )
- Lateral ventricular infarction
- Pre - excitation
- Situs inversus
- Left posterior fascicular block is diagnosed when axis b/w : 90-180 with rS complex in I and avL as well as qR complex in III + avF ( with QRS <0.12s), provided that other causes of right axis deviation have been excluded
Left axis deviation
- LBBB
- Left ventricular hypertrophy
- Inferior infarction
- Pre - excitation
- Left anterior fascicular block is diagnosed if the axis is b/w 45 - 90 with qR complex in aVL + QRS > 0.12s , provided that other causes of left axis deviation have been excluded
Causes of ST segment elevation
- Ischemia
- ST segment elevation MI ( STEMI /STE - AKS)
- Prinzmetal’s angina ( coronary vasospasm )
- Early repolarization
- Perimyocarditis
- LBBB
- Left ventricular hypertrophy
- Hyperkalemia
- Pulmonary embolism
- Pre - excitation
- Aortic dissection engaging the coronary arteries
- Left ventricular aneurysm
Cause of ST segment depression
- Ischemia
- Non ST segment elevation MI ( NSTEMI / NSTE - AKS)
- Hyperventilation
- Hypokalemia
- High sympathetic tone
- Digoxin
- LBBB
- RBBB
- Pre - excitation
- Left ventricular hyperthrophy
- Right ventricular hypertrophy
- Heart failure
- Tachycardia
In limb leads the amplitude is highest in 1)____
In chest leads the amplitude is highest in V2-V3 2)____
1) Lead II
2) V2-V3
T wave inversion w/o simultaneous ST segment deviation
- Post ischemic sign
- Pulmonary embolism
- Perimyocarditis ( after normalization of the ST segment elevation , T waves become inverted in perimyocarditis )
- Cardiomyopathy
T wave inversion with simltaneous ST segment deviation
Acute ( ongoing ) myocardial ischemia
High T waves
1.Nrmal variant
2.Early repolarization
3.Hyperkalemia
4.Left ventricular hypertrophy
5.LBBB
6.Ocassionally perimyocarditis
High (hyperacute) Twaves may be seen in very early phase of STEMI
ECG features of Junctional Escape Rhythm
- Junctional rhythm with a rate of 40-60 bpm
- QRS complexes are typically narrow (< 120 ms)
- No relationship between the QRS complexes and any preceding atrial activity (e.g. P-waves, flutter waves, fibrillatory waves)
Terminology of junctional rhythms
Junctional bradycardia = junctional rhythm at a rate of < 40 bpm
Junctional escape rhythm = junctional rhythm at a rate of 40-60 bpm
Accelerated junctional rhythm = junctional rhythm at 60-100 bpm
Junctional tachycardia = junctional rhythm at > 100 bpm
