A patient is admitted to the emergency room for evaluation of a possible myocardial infarction (MI). Which diagnostic procedure would be the priority?

Choice A rationale:

Digoxin is a medication that slows the heart rate. It would be contraindicated in this patient because they are already bradycardic.

Administering digoxin could further slow the heart rate and worsen the patient's symptoms.

Additionally, digoxin can have a negative inotropic effect, which could further compromise the patient's hemodynamic status. Choice B rationale:

While it is important to continue to monitor the patient, this is not an intervention that will address the patient's bradycardia and hypotension.

The patient is already symptomatic, and their heart rate and blood pressure are likely to continue to decline without intervention. Choice C rationale:

Defibrillation is used to treat life-threatening arrhythmias such as ventricular fibrillation and pulseless ventricular tachycardia.

It is not indicated for sinus bradycardia.

Choice D rationale:

Transcutaneous pacing is a non-invasive method of pacing the heart.

It can be used to temporarily increase the heart rate in patients with symptomatic bradycardia.

This is the most appropriate intervention for this patient because it will address the underlying problem of bradycardia and improve the patient's hemodynamic status.

Choice A rationale:

Blocking impulse transmission to the AV node is not the primary function of an ICD. This is typically achieved through medications such as beta blockers or calcium channel blockers, or through a procedure called AV node ablation.

While ICDs can sometimes have a secondary effect of slowing AV node conduction, their primary purpose is to actively monitor heart rhythm and deliver electrical shocks when necessary to restore normal rhythm.

Choice B rationale:

Assuming the function of the SA node is not the primary function of an ICD. The SA node, located in the right atrium, is the natural pacemaker of the heart, responsible for initiating electrical impulses that trigger each heartbeat.

While ICDs can sometimes pace the heart if the SA node is not functioning properly, their primary purpose is to intervene when life-threatening arrhythmias occur, rather than to continuously regulate heart rate.

Choice C rationale:

Triggering electrical impulses to the heart is the core function of an ICD. It continuously monitors heart rhythm and can deliver electrical shocks to restore normal rhythm when it detects potentially dangerous arrhythmias, such as ventricular tachycardia or ventricular fibrillation.

These shocks are designed to interrupt chaotic electrical activity in the heart and allow the natural pacemaker to regain control, preventing cardiac arrest and sudden cardiac death.

Choice D rationale:

Increasing ventricular conduction is not the primary function of an ICD. In fact, in some cases, ICDs may actually slow down ventricular conduction to prevent certain types of arrhythmias.

Medications or procedures such as cardiac resynchronization therapy (CRT) are specifically designed to improve ventricular conduction in patients with heart failure.