ECG Flashcards
Two methods to calculate heart rate
- 300/Large squares between R waves
- Count R waves in strip and multiply by 6
Definition of Bradycardia and the causes
< 60bpm
- Fitness
- Hypothyroidism
- Hypothermia
- Beta-blockers
- Digoxin
- Amiodarone
- MI
- Vasovagal syncope
Definition of Tachycardia and the causes
> 100bpm
- Hyperthyroidism
- Anaemia
- Fever
- Pregnancy
- Exercise
- Congestive cardiac failure
- AF
- PE
- MI
- Hypovolaemic shock
Definition of Sinus Rhythm
Normal rhythm where the electrical stimuli initiates at the sinoatrial node and leads to ventricular dpolarisation
- Normal sinus rhythm - 60-100, with p waves
- Sinus bradycardia - < 60, with p waves
- Sinus tachycardia - > 100, with p waves
What leads are positive and negative in normal, left and right axis deviation
- Normal Axis - QRS positive in lead I and aVF
- Left axis deviation - QRS positive in lead I, lead 2 is negative and aVF is negative
- Right axis deviation - QRS negative in lead I and positive in aVF
Causes of Left axis deviation
- LVH
- Left anterior fascicular block
- LBBB
- Inferior MI
- Wolff-Parkinson-White syndrome
Causes of right axis deviation
- RVH
- Left posterior fascicular block
- RBBB
- Dextrocardia
- Lateral wall MI
- Wolff-Parkinson-White syndrome
What is a P wave, and what is P mitrale and P pulmonale
P wave is atrial depolarisation
- P mitrale - bifid P wave = left atrial enlargement
- P pulmonale - peaked P wave = right atrial enlargement
What causes increased amplitude of the QRS complex
Left ventricular hyprtrophy - increase R wave amplitude in left side leads (V4-6, I, aVL) and increased S wave amplitude in right side leads (II, aVR, V1-3)
If the QRS is greater than 120ms what may cause it?
Bundle Branch Blockages
- LBBB - WiLLiaM
- RBBB - MaRRoW
Causes of LBBB
- IHD
- AS
- HTN
- Dilated cardiomyopathy
- Hyperkalaemia
- Digoxin
In which leads should the T wave be -ve and +ve
T waves can be inverted in V1,2 but should be +ve in V3-6
Causes of RBBB
- RVH
- PE
- IHD
- RHD
- Myocarditis
What is a U wave
- +ve deflection after T wave
- seen in low rates
- best seen in leads V2, V3
- Large = Hypo - K, Ca, Mg
- Inverted = MI, Cardiomyopathy
Cause of small or large or inverted T waves
T wave represents ventricular repolarisation
- Small = hypokalaemia
- Large = hyperkalaemia
- Inverted = MI, BBB, PE, ventricular hypertrophy
What are the types of AV blocks associated with prolonged PR interval >200ms
1) First degree AV block - prolonged PR interval
2) Second degree AV block
- Mobitz type 1 (Wecknebach) - progressive prolongation of PR interval culminating in a non-conducted P wave. Usually temporary.
Causes: Beta-blockers, Ca-channel blockers, Inferior MI, myocarditis - Mobitz type 2 - intermittent non-conducted P waves without progressive prolongation of the PR interval. Usually not temporary.
Causes: Beta-blockers, Ca-channel blockers, Anterior MI
3) Third degree AV block - no P waves are transmitted to ventricles. High risk of sudden death - need pacemaker.
causes: same as second degree heart block, which progresses
What causes reduced PR wave (<120ms)
Wolff-Parkinson-White (pre-excitation syndrome)
- Involves presnce of an accessory pathway connecting the atria and ventricles. Because this pathway isnt slowed at the AV node, there is a short PR interval
- On ECG –> Short PR interval, Delta wave (Slurred upstroke of QRS), widened QRS complex
What is a pathological Q wave
- Seen in leads V1-3
- Greater than 25% depth of QRS complex
- Greater than 2mm deep and wider than 40ms
Pathological Q waves indicate current or previous MI
Causes of poor R wave progression
- LVH
- Prior anterio-sepctal MI
- Inaccurate lead placement
Causes of ST elevation
- MI (STEMI)
- Pericarditis - widespread concave ST elevation associated with PR depression in multiple leads
- coronary vasospasm
- LBBB
Cause of ST depression
- Posterior MI
- Myocardial ischaemia in NSTEMI
- Digoxin - hockey stick depression
- Hypokalaemia
- RBBB
Causes of prolonged QT interval (QT>440 in men, >460 in women or QTc >500)
- Drugs (Antipsychotics, anti-arrhythmics, anti-depressants)
- Hypo - K, Mg, Ca
- MI
What condition is a long QT interval associated with
Torsades de Pointes
- It is characterized by rapid, irregular QRS complexes, which appear to be twisting around the ECG baseline. This arrhythmia may cease spontaneously or degenerate into ventricular fibrillation.
ECG charactristics of hypokalaemia
- Increased amplitude of P wavs
- prolongation of PR intrval
- T wave flattening or inversion
- ST depression
- Prominent U waves
ECG charactristics of hyperkalaemia
- T wave peaks
- P waves lost
- QRS widens - eventually widens to become sine wave
ECG changes in PE
- Tachycardia
- SI QIII TIII
- Right axis dviation
- T wave inversion in V1-4
- P pulmonale
What is Brugada syndrome and what are the ECG characteristics
Inherited channelopathy affecting the myocardial sodium channels, which leads to paroxysmal ventricular arrhythmias and sudden cardiac death in young patients
- ST segment elevation followedby negative T wave
Atrial Fibrillation ECG changes
- Loss of P waves
- Irregularly irregular rhythm
- Narrow QRS complex
ECG changes in Sinus Ventricular Tachycardia
- Regular rate
- Tachycardia
- P and T waves merged
- Narrow complex (Note VT is sam but with broad complex)
ECG changes in Atrial Flutter
- Regular rhythm
- P waves occur before every QRS complex
- Sawtooth appearance of regular P waves especially in leads II, III, aVF
- Narrow QRS
This tracing is Sinus Bradycardia. Look for rhythm that is regular, with heart rate that is slow (< 60 bpm). Notice that the P wave is normal. The PR interval is normal (0.12-0.20 sec). The QRS is typically normal (0.06-0.10 sec).
This tracing is Premature Ventricular Complex Trigeminy. Look for rhythm that is irregular, with heart rate that is the underlying rate. Notice that the P wave is absent. The PR interval is not measurable. The QRS is typically wide (> 0.10 sec), bizarre appearance. PVC appears every third beat.
This tracing is Premature Junctional Complex. Look for rhythm that is regular with premature beats, with heart rate that is the underlying rate. Notice that the P wave is present before, during (hidden) or after qrs, if visible it is inverted. The PR interval is absent or short. The QRS is typically normal (0.06-0.10 sec).
Electrical Impulse originated from AV node. Caused by cardiotoxic drugs, electrolyte imbalance, mitral valve surgery.
This tracing is Supraventricular Tachycardia. Look for rhythm that is regular, with heart rate that is fast (150-250 bpm). Notice that the P wave is merged with t wave. The PR interval is normal (0.12 sec). The QRS is typically normal (.10 sec). PR interval can be difficult to measure.
This tracing is Second Degree Heart Block Type I. Look for rhythm that is irregular but with progressively longer pr interval lengthening, with heart rate that is the underlying rate. Notice that the P wave is normal. The PR interval is progressively longer until a qrs complex is missed, then cycle repeats. The QRS is typically normal (0.06-0.10 sec)
This tracing is Sinus Arrhythmia. Look for rhythm that is irregular, varying with respiration, with heart rate that is normal (60-100 bpm) and rate may increase during inspiration. Notice that the P wave is normal. The PR interval is normal (0.12-0.20 sec). The QRS is typically normal (0.06-0.10 sec). Heart rate frequently increases with inspiration, decreasing with expiration.
This tracing is Ventricular Tachycardia. Look for rhythm that is regular, with heart rate that is fast (100-250 bpm). Notice that the P wave is absent. The PR interval is not measurable. The QRS is typically wide (>0.10 sec), bizarre appearance.
This tracing is Junctional Escape Rhythm. Look for rhythm that is regular, with heart rate that is slow (40-60 bpm). Notice that the P wave is present before, during (hidden) or after qrs, if visible it is inverted. The PR interval is not measurable. The QRS is typically normal (0.06-0.10 sec).
A junctional escape beat is a delayed heartbeatoriginating not from the atrium but from an ectopicfocus somewhere in the atrioventricular junction. It occurs when the rate of depolarization of the sinoatrial node falls below the rate of the atrioventricular node. This dysrhythmia also may occur when the electrical impulses from the SA node fail to reach the AV node because of SA or AV block.
This tracing is Idioventricular Rhythm. Look for rhythm that is regular, with heart rate that is slow (20-40 bpm). Notice that the P wave is absent. The PR interval is not measurable. The QRS is typically wide (>0.10 sec), bizarre appearance.
if the ventricle does not receive triggering signals at a rate high enough from either the SA node or the AV (Atrioventricular) node, the ventricular myocardium itself becomes the pacemaker
This tracing is Premature Atrial Complex. Look for rhythm that is irregular, with heart rate that is usually normal but depends on underlying rhythm. Notice that the P wave is premature, positive and shape is abnormal. The PR interval is normal or longer. The QRS is typically 0.10 sec or less. Wandering baseline artifact can be seen in this tracing.
This tracing is Pacemaker Single Chamber Ventricular. Wandering baseline artifact can be seen in this tracing.
In a single-chamber system, one lead is used, most commonly pacing the right ventricle. Dual-chamber pacemakers have two leads, placed in the right atrium and right ventricle.
This tracing is Pacemaker Single Chamber Atrial. Look for rhythm that is regular, with heart rate that is 60 bpm. Notice that the P wave is normal. The PR interval is normal. The QRS is typically normal.
This tracing is First Degree Heart Block. Look for rhythm that is regular, with heart rate that is the underlying rate. Notice that the P wave is normal. The PR interval is prolonged (>0.20 sec). The QRS is typically normal (0.06-0.10 sec). A first degree AV block occurs when electrical impulses moving through the Atrioventricular (AV) node are delayed (but not blocked). First degree indicates slowed conduction without missed beats.. Muscle tremor noise is present in this tracing.
This tracing is Third Degree Heart Block. Look for rhythm that is regular, but atrial and ventricular rhythms are independent, with heart rate that is characterized by atrial rate usually normal and faster than ventricular rate. Notice that the P wave is normal shape and size, may appear within qrs complexes. The PR interval is absent: the atria and ventricles beat independently.. The QRS is typically normal, but wide if junctional escape focus.
This tracing is Wolff-Parkinson-White Syndrome. Look for rhythm that is regular unless atrial fibrillation present, with heart rate that is normal (60-100 bpm). Notice that the P wave is normal. The PR interval is can be short (<0.12 sec). The QRS is typically usually wide (> 0.12 sec). Look for short PR interval and/or delta wave A delta wave (positive or negative) distorts the early part of the QRS complex.
This tracing is Sinus Tachycardia. Look for rhythm that is regular, with heart rate that is fast (> 100 bpm). Notice that the P wave is normal, may merge with t wave at very fast rates. The PR interval is normal (0.12-0.20 sec). The QRS is typically normal (0.06-0.10 sec). QT interval shortens with increasing heart rate.
This tracing is Atrial Flutter. Look for rhythm that is regular or irregular, with heart rate that is fast (250-350 bpm) for atrial, but ventricular rate is often slower. Notice that the P wave is not observable, but saw-toothed flutter waves are present. The PR interval is not measurable. The QRS is typically normal (0.06-0.10 sec).
This tracing is Ventricular Fibrillation. Look for rhythm that is highly irregular, with heart rate that is unmeasurable. Notice that the P wave is absent. The PR interval is not measurable. The QRS is typically none. EKG tracings is a wavy line.
This tracing is Supraventricular Tachycardia. Look for rhythm that is regular, with heart rate that is fast (150-250 bpm). Notice that the P wave is merged with t wave. The PR interval is normal (0.12 sec). The QRS is typically normal (.10 sec). PR interval can be difficult to measure
