His frowning face was pallid and quivered.

Calvin was of middle stature; his complexion was somewhat pallid and dark; his eyes, to the latest clear and lustrous, bespoke the acumen of his genius.

An electrocardiogram (ECG, EKG) that records the electrical activity in the heart may be used to check for heart rhythm abnormalities, such as long QT syndrome, in children who have had a pallid breath holding spell.

Up to 17 percent of children with pallid BHS will experience syncope (fainting spells) as adults, usually in response to fear, injury, or emotional stress.

In a pallid BHS the brain sends a signal via the vagus nerve that severely slows the heart rate, leading to a temporary cessation of breathing and loss of consciousness.