Horizontal Heart

Report:

Sinus rhythm

Normal axis (-14o)

Horizontal heart position

Late transition

ECG within normal limits

Comment:

The electrical heart position is defined by leads aVL and aVF alone; the term is a descriptive one, only useful if there is no abnormal right or left axis deviation. The horizontal position is present when the two leads diverge from each other, as in this patient. It is associated with stocky, pyknic build and obesity; one can but speculate that this candidate for cholecystectomy was fit, fat, fair, fertile, forty-to-fifty and flatulent, perhaps with a family history of cholelithiasis!

As Marriott puts it, “there are times when it is convenient to refer to a heart with an axis in the neighbourhood of 0o to – 30o as a horizontal heart, and to one with an axis between +60o and +90o as a vertical heart”107. That’s all there is to it.

Late transition refers to equiphasic QRS in lead V5 instead of V3 or V4; it is synonymous with clockwise rotation. As (again) Marriott would put it, “such rotations are not necessarily abnormal”108. This, too, is a purely descriptive term. Note how, in lead V5, the stage of respiratory cycle affects the R/S ratio, shifting the transitional zone to and from V6. This is of some significance, since R/S ration of less than 1.0 in V5 could be considered abnormal; it is less than 1.0 in V5 and V6 in less than 2.5% normal subjects.