The Patient: This ECG was obtained from an elderly man who was suffering an exacerbation of congestive heart failure. He had a history of CHF and hypertension. We do not have other history available to us.
The ECG: The rhythm is sinus at 97 bpm (fast for this patient). It is regular with no ectopy. The PR interval is 155 ms (.15 seconds), and the P waves are upright in the inferior leads. The frontal plane QRS axis is -56 degrees – abnormally leftward. Notice that Leads II, III, and aVF are all negative. AVR is equiphasic – the axis travels perpendicular to the positive electrode of aVR, toward the patient’s left shoulder. The QRS duration is 111 ms (.11 sec.). This is very close to being wide enough for a diagnosis of left bundle branch block, and represents poor conduction throughout the ventricles. On the chest leads side, there is poor R wave progression. V1 through V4 look almost the same, small r and large S.
The ST segments are generally concave up, and the J points are at the baseline – no ST elevation or depression. There are no pathological Q waves, unless we count V1, which may have lost it’s Q wave as part of the general poor R wave progression.
Interpretation: The fast rate is probably attributable to the patient’s difficulty breathing, as this ECG was obtained in the Emergency Department before treatment had a chance to alleviate his symptoms. The other most noticeable abnormality on this ECG is the axis shift – normally, Lead II is positive. While there are many reasons for axis shift (myocardial infarction, chamber enlargement, body habitus, etc.), nearly all can be ruled out in this patient. Instead, he has the ECG signs of left anterior fascicular block, also called left anterior hemiblock. Think of it as half a left bundle branch block, because the left anterior fascicle is blocked while the posterior fascicle is still conducting. The effects on the ECG are:
· Left axis deviation, greater than -45 degrees.
· A slightly widened QRS.
· qR pattern in Leads I and aVL (lateral leads).
· rS pattern in inferior leads.
· Possible interference in normal R wave progression, producing a pattern that resembles anterior M.I.
Studies have shown some association of LAFB with other cardiac conditions like CHF and atrial fib. But, as a single ECG finding, it is considered rather benign, possibly signaling fibrosis or other disease beginning to affect the interventricular conduction system.
EDIT: After writing this, Drs Grauer, Jones, and Parrinello were kind enough to weigh in on the significance of the wide QRS and the tall T waves. Please read their comments below for a fuller understanding of this ECG.
Had we more information about the patient, we would not have to speculate. ECGs are best evaluated with full clinical information.