A 43-year-old guy is examined for sporadic heart palpitations brought on by stress. The patient recalls a quick onset of lightheadedness and shortness of breath, as well as a hammering sensation in the chest. He's never had syncope. The patient's family history is ordinary, and they have no history of cardiac disease. Following a preliminary examination, he receives verapamil treatment and reports a significant decrease in the frequency of palpitation events. The electrical activity of a particular class of cardiac cells in the patient's heart is depicted in the trace below. Which of the following effects would verapamil administration most likely have on these cells?

Question

A 43-year-old guy is examined for sporadic heart palpitations brought on by stress. The patient recalls a quick onset of lightheadedness and shortness of breath, as well as a hammering sensation in the chest. He's never had syncope. The patient's family history is ordinary, and they have no history of cardiac disease. Following a preliminary examination, he receives verapamil treatment and reports a significant decrease in the frequency of palpitation events. The electrical activity of a particular class of cardiac cells in the patient's heart is depicted in the trace below.  Which of the following effects would verapamil administration most likely have on these cells?

Quizplus · Accepted Answer

Eductional Objective: Recurrent nodal arrhythmias are frequently prevented by the use of class IV antiarrhythmics, such as verapamil and diltiazem (eg, paroxysmal supraventricular tachycardia). Phase 4 (spontaneous depolarization) and phase 0 of the heart's slow-responding cardiac tissues are slowed by their blockage of calcium channels (upstroke). The sinoatrial and atrioventricular nodes' impulse conduction velocity is slowed down as a result.

A 43-Year-Old Guy Is Examined for Sporadic Heart Palpitations Brought