Which of. The heart rhythms would be least likely to present in an unresponsive patient who you believe has experienced a severe heart attack and is in cardiac arrest?

A. Ventricular tachycardia
B. Asystole
C. Ventricular fibrillation
D. Normal sinus rhythm

Answer: D. Normal sinus rhythm
In a normally functioning heart, the heart's electrical impulse is generated from the sinoatrial node. The electrical impulse then travels through the heart;s conduction system, depolarization the muscle in an organized fashion and producing the contractions that pump blood into the ventricles and then through the body. This electrical activity is called normal sinus rhythm. It will produce an ECG pattern of regularly spaced peaks that occur between 60 an 100 times each minute, separated by nearly flat lines. A patient who is unresponsive and is not in cardiac arrest it's a heart attack is more likely to have a rapid heart rate (tachycardia). If the patient is unresponsive and in cardiac arrest, statistically the presenting rhythm in the first minutes after arrest are either ventricular fibrillation or pulseless ventricular tachycardia. After prolonged period of unresponsiveness and arrest, the rhythm will eventually become asystole.