Why do patients with dual chamber pacemaker (DUAL SIS) syndrome go into cardiac arrest

From the Guidelines

Patients with dual chamber pacemaker syndrome can go into cardiac arrest due to inappropriate pacemaker timing that causes hemodynamic compromise, and management includes immediate reprogramming of the pacemaker to optimize AV synchrony, as supported by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.

Pathophysiology of Dual Chamber Pacemaker Syndrome

The primary mechanism involves retrograde ventriculoatrial conduction, where ventricular pacing causes blood to flow backward into the atria during contraction, reducing ventricular filling and subsequently decreasing stroke volume and blood pressure. This occurs when there is suboptimal coordination between atrial and ventricular contractions, leading to decreased cardiac output.

Risk Factors for Severe Manifestations

Patients with pre-existing heart failure or structural heart disease are at higher risk for severe manifestations of this syndrome, as they have less cardiac reserve to compensate for the hemodynamic changes.

Management and Prevention

Management includes immediate reprogramming of the pacemaker to optimize AV synchrony, typically by adjusting the AV delay or changing the pacing mode to DDD if the patient was in a non-physiologic pacing mode. In severe cases, temporary pacing may be needed while the permanent device is reprogrammed. The use of dual-chamber pacemakers may be beneficial in preventing hemodynamic compromise and improving symptom recurrence in older adults with concomitant sinus node dysfunction or conduction system disease, as suggested by the 2013 ACCF/AHA/HRS focused update incorporated into the ACCF/AHA/HRS 2008 guidelines for device-based therapy of cardiac rhythm abnormalities 1.

Key Considerations

• The 2019 ACC/AHA/HRS versus ESC guidelines for the diagnosis and management of syncope highlight the importance of pacemaker implantation in patients with recurrent reflex syncope, particularly those with cardioinhibitory or mixed forms of carotid sinus syndrome 1.
• The task force on sudden cardiac death of the European Society of Cardiology notes that malignant ventricular arrhythmia remains the commonest single cause of sudden cardiac death in patients with dilated cardiomyopathy, and deaths due to this mechanism account for the majority of sudden cardiac deaths in patients with less severe disease 1.

Recommendations

• Optimize AV synchrony by adjusting the AV delay or changing the pacing mode to DDD, as needed, to prevent hemodynamic compromise and improve symptom recurrence in patients with dual chamber pacemaker syndrome.
• Consider dual-chamber pacemaker implantation in patients with carotid sinus syndrome who require permanent pacing, as supported by the 2017 ACC/AHA/HRS guideline for the evaluation and management of patients with syncope 1.

From the Research

Dual Chamber Pacemaker (DUAL SIS) Syndrome and Cardiac Arrest

• The provided studies do not directly address why patients with dual chamber pacemaker (DUAL SIS) syndrome go into cardiac arrest.
• However, the studies discuss the management of cardiac arrest, including the use of medications such as epinephrine, vasopressin, and antiarrhythmics 2, 3, 4, 5, 6.
• These medications are used to try to restore a normal heart rhythm and improve survival rates, but their effectiveness is still debated 2, 3, 5, 6.
• The studies suggest that while these medications may improve short-term survival, they may not necessarily improve long-term survival or functional recovery 2, 3, 6.
• There is no direct evidence in the provided studies to explain why patients with DUAL SIS syndrome are at risk of cardiac arrest.

Cardiac Arrest Management

• The American Heart Association (AHA) guidelines emphasize the importance of immediate recognition and activation of the emergency response team, effective chest compressions, rapid defibrillation, effective advanced life support (ALS), and integrated postresuscitation care 4.
• The use of cardioactive medications, such as epinephrine, vasopressin, and antiarrhythmics, is part of the ALS protocol 4, 5.
• The effectiveness of these medications in improving survival rates and functional recovery is still being researched and debated 2, 3, 5, 6.

Medications Used in Cardiac Arrest

• Epinephrine is the primary drug administered during cardiopulmonary resuscitation (CPR) to reverse cardiac arrest 2, 6.
• Vasopressin and antiarrhythmics, such as amiodarone and lidocaine, are also used in cardiac arrest management 2, 3, 4, 5.
• The use of these medications is guided by the AHA guidelines and is based on the patient's specific condition and the underlying cause of the cardiac arrest 4, 5.