ECG Interpretation Flashcards
Left anterior Fasciular block
+ QR complexes in lateral leads
- RS complexes in inferior leads
- Left axis deviation
- slightly widened Qr complexes
ECG criteria to diagnose left anterior fascicular block
Left axis deviation (usually -45 to -90 degrees)
qR complexes in leads I, aVL (lateral-antero leads)
rS complexes in leads II, III, aVF (inferior leads)
Prolonged R wave peak time in aVL > 45ms
causes of left anterior fasciaulr block
In the absence of manifest heart disease and in association with aging, left anterior fascicular block is attributed to degenerative disease of the conducting system,27 sclerosis of the left side of the cardiac skeleton,28 or myocardial fibrosis
ECG diagnostic criteria for left bundle branch block
Broad S wave in V1
Long QRS duration >120 ms
broad, notched “M-shaped” R wave in V6.
“wiLLiaM”-Left block= S and M wave
Label R and S wave
qR wave is positive, qS wave is nefative
LBBB
LBBB with AF: Note the appropriate discordance manifesting as ST depression in leads V5-6, as well as mild ST elevation in leads V2-3.
Causes of left bundle branch block
Aortic stenosis
Ischaemic heart disease
Hypertension
Dilated cardiomyopathy
Anterior MI
Lenègre-Lev disease: primary degenerative disease (fibrosis) of the conducting system
Hyperkalaemia
Digoxin toxicity
Incomplete LBBB is diagnosed when typical LBBB morphology is associated with _____
Incomplete LBBB is diagnosed when typical LBBB morphology is associated with a QRS duration < 120ms.
normal duration for QRS complex
under 120
normal QT interval
In general, the normal QT interval is below 400 to 440 milliseconds (ms), or 0.4 to 0.44 seconds. Women have a longer QT interval than men. Lower heart rates also result in a longer QT interval.
ECG diagnostic criteria for right bundle branch block
- “M” waves on anterior V1 leads (R wave, sometimes notched like bunny ears
- W waves on V5/6 leads (negative S waves), slurred.
- QRS duration >120ms
MaRrOW
Is T wave invesion appropriate in RBBB in V1?
yes, because the R wave is huge. It’s okay to have idscordant T waves
Appropriate discordance with ST depression and/or T-wave inversion in right precordial leads (V1-3).
RBBB
Causes of RBB
Right ventricular hypertrophy / cor pulmonale
Pulmonary embolus
Ischaemic heart disease
Rheumatic heart disease
Congenital heart disease (e.g. atrial septal defect)
Myocarditis
Cardiomyopathy
Lenègre-Lev disease: primary degenerative disease (fibrosis) of the conducting system
malignant syndrome that can look like right bundle branch block
Brugada syndrome
Brugada syndrome is due to a mutation in the cardiac ___ channel gene. This is often referred to as a ___ channelopathy. O
Brugada syndrome is due to a mutation in the cardiac sodium channel gene. This is often referred to as a sodium channelopathy. O
diagnostic criteria for right ventricular hypertrophy
- right axis deviation
- dominant R wave in V1 (R/S ratio >1)
- Dominant S wave in V5 or V6 (R/S ratio <1)
- QUS duration <120 ms (ie NOT RBBB)
Supporting criteria
Right atrial enlargement (P pulmonale).
Right ventricular strain pattern = ST depression / T wave inversion in the right precordial (V1-4) and inferior (II, III, aVF) leads.
S1 S2 S3 pattern = far right axis deviation with dominant S waves in leads I, II and III.
Deep S waves in the lateral leads (I, aVL, V5-V6).
Other abnormalities caused by RVH
Right bundle branch block (complete or incomplete).
Signs of right heart strain/right ventricular strain
- ST depression and T wave inversion in leads corresponding to right ventricle (ie, AvR, V1, V2, V3)
- +/- right axis deviation
- Dominant R wave in V1
- Dominant S wave in V5 or V6/
causes of right heart hypertrophy and strain
Pulmonary hypertension *(left heart strain is the number one cause of right heart strain)
Mitral stenosis
Pulmonary embolism
Chronic lung disease (cor pulmonale)
Congenital heart disease (e.g. Tetralogy of Fallot, pulmonary stenosis)
Arrhythmogenic right ventricular dysplasia (ARVD)
person comes in with shortness of breath after long haul flight
- S1Q3T3 present
- normal axis
- T wave inversion (concordant with negative S waves = bad) in V1-V3
overall, right ventricular strain pattern dur to pulmonary embolism
this person had corpulmonale
re; core pulmonale is a finding in COPD where you get:
Chronic hypoxaemia causes reflex vasoconstriction in the pulmonary arterioles (“hypoxic pulmonary vasoconstriction”), with consequent elevation of pulmonary arterial pressures
Destruction of lung tissue with loss of pulmonary capillaries increases the resistance of the pulmonary vascular bed by reducing its effective surface area
Over time, this chronic elevation of pulmonary arterial pressures results in compensatory right atrial and right ventricular hypertrophy
IN this ecg, you have:
- St depression and T wave inversion in V1-V4, and lead III
- Right axis deviation, plus dominant R wave in V1.
overall, RAD= right ventricular hypertrophy finding, and ST dep in V1-V4= right ventricular strain.
3 key findings in hypokalemia
- T wave inversion
- U wave
- ST depression
4 key findings in hyperkalemia
- bradycardia (if bad)
- peaked T waves
- flattened P waves, PR prolongation
- long QRS complex
Potassium is vital for regulating the normal electrical activity of the heart. Increased extracellular potassium reduces myocardial excitability, with depression of both pacemaking and conducting tissues.
Progressively worsening hyperkalaemia leads to suppression of impulse generation by the SA node and reduced conduction by the AV node and His-Purkinje system, resulting in bradycardia and conduction blocks and ultimately cardiac arrest.
This ECG displays many of the features of hyperkalaemia:
- Prolonged PR interval.
- Broad, bizarre QRS complexes — these merge with both the preceding P wave and subsequent T wave.
- Peaked T waves.
This patient had a serum K+ of 9.3
phenomenon that severe hypokalemia can trigger
hypokalemia
a prolonged QT interval can decompensate into ___
torsade des points
- Common causes for torsades de pointes include drug-induced QT prolongation and less often diarrhea, low serum magnesium, and low serum potassium or congenital long QT syndrome
Massive pericardial effusion produces a characteristic ECG triad of:
Low QRS voltage
Tachycardia
Electrical alternans
A pleural effusion can be caused by pericarditis or cardiac tamponade
Characteristic ECG findings of pericarditis
Widespread concave ST elevation and PR depression throughout most of the limb leads (I, II, III, aVL, aVF) and precordial leads (V2-6)
Reciprocal ST depression and PR elevation in lead aVR (± V1)
Sinus tachycardia is also common in acute pericarditis due to pain and/or pericardial effusion
Causes of pericarditis
Classification can be primary versus secondary, acute versus chronic, or infectious versus immune-mediated.
Infectious – mainly viral (e.g. coxsackie virus); occasionally bacterial, fungal, TB.
Immunological – SLE, rheumatic fever
Uraemia
Post-myocardial infarction or following cardiac surgery (Dressler’s syndrome)
Trauma
Paraneoplastic syndromes
Drug-induced (e.g. isoniazid, cyclosporin)
Post-radiotherapy
Acute Pericarditis:
Widespread concave ST elevation and PR depression is present throughout the precordial (V2-6) and limb leads (I, II, aVL, aVF).
There is reciprocal ST depression and PR elevation in aVR.
Spodick Sign of Pericarditis
Downsloping TP segment seen as an early ECG manifestation in ~80% of patients with pericarditis, best visualised in leads II and the lateral precordial leads
