Northwest Axis on Electrocardiogram: Decoding an Unusual Cardiac Axis in a Young Patient

Area of Science:

• Cardiology
• Pediatric Cardiology
• Cardiac Surgery

Background:

• A
• northwest
• cardiac axis, characterized by specific electrocardiographic patterns, is observed in a patient with Fontan circulation.
• The patient exhibits electrocardiographic features indicative of right ventricular (RV) pressure overload.
• This case highlights a unique presentation within the context of complex congenital heart disease management.

Purpose of the Study:

• To describe a patient with a
• northwest
• cardiac axis and RV pressure overload in Fontan circulation.
• To elucidate the underlying mechanisms and clinical significance of this specific electrocardiographic finding.

Main Methods:

• A 28-year-old woman with a history of Fontan procedure underwent routine follow-up.
• Electrocardiography revealed a frontal QRS axis between -90° and ±180°, consistent with RV pressure overload.
• Clinical examination included assessment of murmurs, oxygen saturation, and laboratory tests (hemoglobin, hematocrit).

Main Results:

• The patient presented with a
• northwest
• cardiac axis and signs of RV pressure overload.
• Physical examination revealed a pansystolic murmur, digital clubbing, and low oxygen saturation (85%).
• Laboratory results showed elevated hemoglobin (19 g/dL) and hematocrit (62%), suggesting chronic hypoxia.

Conclusions:

• In atrioventricular canal defects with Fontan circulation, a
• northwest
• cardiac axis on electrocardiography signifies altered RV activation and remodeling.
• This axis deviation often persists from childhood into adulthood.
• It is frequently secondary to RV outflow tract obstruction.