The goal of this clinical trial is to learn if backup pacing at an increased rate improves hemodynamics in adults with relative bradycardia, a permanent pacemaker, and cardiogenic shock. The main question it aims to answer is:

Does increasing the backup pacing rate to 100 beats per minute lead to improved cardiac index compared to a backup pacing rate of 75 beats per minute

Participants who are already hospitalized in the Cardiovascular Intensive Care Unit with a permanent pacemaker and pulmonary artery catheter in place will be enrolled in this study. Participants will be exposed to each pacemaker rate in a randomized order with hemodynamics assessed after 10 minutes at each rate.

Inclusion Criteria:

• Adults (age 18 and older)
• Located in the CVICU
• FDA approved permanent pacemaker in place (inclusive of dual-chamber and Bi-Ventricular ICDs) with labeling that allows backup pacing setting at 100 bpm.
• Receiving a vasopressor or Inotrope for at least 4 hours
• Average HR ≤ 75 bpm over the last hour (on Telemetry review)
• Pulmonary artery catheter in place with functioning thermistor and pulmonary artery port.

Exclusion Criteria:

• Single chamber Implantable Cardiac Defibrillator
• Sinus rhythm with a leadless pacemaker
• Ventricular Tachycardia or Ventricular Fibrillation arrest in last 48 hours
• Hemodynamic instability within the last 4 hours, defined as an increase in the dose of norepinephrine > 10 mcg/min, an increase of epinephrine > 10 mcg/kg/min, or initiation of a second vasopressor
• Alternative indication for pacing rate change (i.e Torsade de Pointes, Recurrent Ventricular Tachycardia)
• Comfort-focused care or anticipated death within 24 hours
• Mechanical circulatory support in place
• Newly discovered pacing system malfunction (lead displacement, loss of capture, elevated capture threshold, significant lead impedance change, battery depletion, undersensing or oversensing)
• Non-English Speaking