Monday, March 9, 2015

An asymptomatic 56-year-old gentleman presents for routine follow-up.

 An asymptomatic 56-year-old gentleman presents for routine follow-up.

1. What are the ECG fi ndings?

2. What ECG fi ndings would concern you during a preoperative evaluation?

What abnormalities are present on the ECG?

There is sinus rhythm at 66 beats/min. Th e axis is deviated left ward, evidenced by
the positive QRS complex in lead I and the negative QRS complex in leads II and
aVF. Th is left -axis deviation is associated with small q waves and large R waves in
leads I and aVL, and small r waves and large S waves in the inferior leads. Th ere is
no evidence of left ventricular hypertrophy or other chamber abnormalities. Th ere
are no pathologic Q waves suggesting prior infarction, and no ST-segment or T-wave
abnormalities. Th e presence of left ward axis deviation in the absence of left ventricular
hypertrophy or prior infarction with this pattern of qR complexes in leads I and
aVL and rS complexes in the inferior leads is consistent with left anterior hemiblock,
also known as left anterior fascicular block. Recall that the His bundle bifurcates into
the left and right bundle branches. Th e left bundle branch further branches into the
left anterior fascicle and the left posterior fascicle. Block in the left anterior fascicle is
more common than block in the left posterior fascicle. Hypertension, ischemic heart
disease, cardiomyopathy, and degenerative conduction system disease of the elderly
(Lev’s syndrome) are all associated with left anterior hemiblock. Th e QRS duration is
normal when left anterior hemiblock alone is present, although a delayed intrins icoid
defl ection (the duration between the onset of the QRS and the peak of the R wave) of
greater than 45 milliseconds should be observed in lead aVL as is present in this case.

What is the diff erential diagnosis for left-axis deviation?

Left -axis deviation can be associated with left anterior hemiblock (as in this case), left
ventricular hypertrophy, prior myocardial infarction, Wolff -Parkinson-White syndrome,
and atrial septal defect.


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