How to manage R on T events in patients with temporary transvenous pacing?

From the Guidelines

To manage R on T events in patients with temporary transvenous pacing, immediately adjust the pacing settings to prevent further episodes, prioritizing asynchronous pacing mode and ensuring proper sensing thresholds are set, as these events can trigger life-threatening arrhythmias. The management of R on T events in this context is critical due to the potential for ventricular tachycardia or fibrillation, especially in patients with acute ischemia, electrolyte disturbances, or structural heart disease 1.

Key Considerations

• Decrease the pacing output to reduce the risk of myocardial stimulation during the vulnerable period, typically to 3-5 mA.
• Switch to asynchronous pacing mode (VOO or DOO) if the R on T phenomenon is occurring due to sensing issues in demand modes.
• Ensure proper sensing thresholds are set, typically 2 mV for ventricular sensing, and adjust sensitivity settings if oversensing is contributing to the problem.
• Correct any electrolyte abnormalities, particularly potassium and magnesium, as these can increase myocardial irritability.
• Consider antiarrhythmic medications such as amiodarone if R on T events persist despite pacing adjustments, with a protocol of 150 mg IV bolus followed by 1 mg/min infusion for 6 hours, then 0.5 mg/min.

Clinical Context

The use of temporary transvenous pacing should be limited to cases where it is absolutely necessary, such as high-degree AV block without escape rhythm or life-threatening bradyarrhythmias, due to the associated risks and complications 1. The preference for positive chronotropic drug infusion over temporary pacing, unless contraindicated, highlights the need for careful consideration in the management of such patients. Given the higher risk of complications with temporary transvenous pacemakers compared to permanent ones, including loss of capture, lead perforation, or dislodgement 1, meticulous monitoring and adjustment of pacing settings are crucial to prevent adverse outcomes like R on T events.

From the Research

R on T Events Caused by Temporary Transvenous Pacing

• R on T events refer to the occurrence of a ventricular premature beat falling on the T wave of the preceding beat, which can lead to life-threatening arrhythmias such as ventricular tachycardia or fibrillation 2.
• Temporary transvenous pacing (TTP) is a medical procedure used to treat life-threatening arrhythmias, and it can cause R on T events due to the pacing stimulus falling on the T wave of the preceding beat.

Management of R on T Events in Patients with Temporary Transvenous Pacing

• The management of R on T events in patients with TTP involves careful monitoring of the patient's cardiac rhythm and adjustment of the pacing parameters to avoid triggering ventricular arrhythmias 3.
• The use of anti-arrhythmic medications, such as beta-blockers, can also help reduce the risk of R on T events by slowing the heart rate and reducing the excitability of the ventricular myocardium 2.
• In some cases, the use of a temporary transvenous pacemaker with a built-in algorithm to detect and prevent R on T events may be necessary 4.

Complications and Outcomes of Temporary Transvenous Pacing

• The complications of TTP include pericardial tamponade, pneumothorax, and non-pericardial bleeding, which can occur in up to 37.9% of patients 5.
• The outcomes of TTP are generally good, with a low incidence of pericardial complications, but clinicians should be mindful of infrequent but serious complications and take steps to mitigate them 5.
• The use of TTP is generally safe, but it requires careful monitoring and management to minimize the risk of complications, including R on T events 6, 3, 4, 5.