Slide 1: 28-year-old male with a history of recurring URIs. Chief concern is dyspnea and cough. What’s the EKG finding?

Slide 2: What’s the axis and why? Step 1. Examine the QRS deflection in Lead one. If it is positive, continue to step 2. If it is negative consider right axis deviation. Step 2. Examine the QRS deflection in aVF. If it is positive, normal axis. Negative 30 degrees to 90 degrees. If it is negative, continue to step 3. Step 3. Up in lead one and down in aVF? Look at Lead two. If it is positive, normal axis. If it is negative, left axis deviation. Graphic showing left axis deviation, normal axis and right axis deviation. Normal vectors with “positive” lead deflection. Our patient has negative lead one and positive aVF. That’s a right axis deviation!

Slide 3: Right axis differential diagnosis. Most common cause? Limb-lead reversal. Right axis deviation can be normal in children or very thin adults. Primary cardiac issues. Dextrocardia, left posterior fascicular block, right ventricular hypertrophy, prior lateral/apical MI, ventricular pre-excitations (i.e. WPW), pulmonic stenosis. Secondary cardiac causes. Elevated pulmonary vascular resistance. Acute includes pulmonary embolism and pulmonary vein occlusion. Chronic includes hypertension and mitral stenosis. Chronic right-sided volume overload i.e. ASD with shunt, tricuspid regurgitation, pulmonic insufficiency, anomalous pulmonary venous return. Chronic lung disease/hypoxia.

Slide 4: What’s the cause of the right axis? Check out the precordial leads. R wave tallest in V1 (typical V1 and V2 tracings appear reversed here). Here, V4 through 6 have small down going deflections. R-wave should increase with normal progression across precordial leads. Bonus limb-lead findings! Catch the negative P waves in lead one? S wave in lead one is very abnormal (depolarizing is always moving away from the left). These clues should alert you to possible dextrocardia!

Slide 5: How do we confirm dextrocardia? A right-sided EKG should show normal progression. With right sided limb leads and precordial leads. Appears normal! Confirm your suspicion with further imaging! Atrial and ventricular depolarization begin on the left and spread to the right in dextrocardia. Graphic showing direction of depolarization in heart. X-ray with cardiac border and stomach bubble labeled.

Slide 6: Associated conditions. Isolated dextrocardia. Right-sided heart. Situs inversus totalis. Reversal of abdominal and thoracic structures i.e. left-sided liver, right-sided stomach, etc. Kartagener’s syndrome. Subgroup of primary ciliary dyskinesia. Triad of situs inversus, chronic sinusitis, and bronchiectasis.

References

  • Ritchie JV, Juliano ML, Thurman RJ. ECG Abnormalities. The Atlas of Emergency Medicine, 4E. Ch 23. Link.

Tags: , , , , ,