Hemodynamic deterioration during simulated supraventricular tachycardia in patients after the Fontan operation

Supraventricular tachycardia (SVT) is becoming of great concern for patients long after the Fontan operation and arterial blood pressure (BP) decreases during SVT may be associated with their morbidity and mortality.

We investigated the BP during supraventricular pacing (SVP) to simulate SVT in these patients. We measured femoral venous pressure (FVP) and plasma norepinephrine (NE) during SVP at 150 and 180 per minute in 20 Fontan patients and recorded the initial BP fall, its recovery and steady-state BP.

Wide QRS duration had a significant impact on a greater BP decline and increases in steady-state FVP and NE at 150 SVP. Changes in BP, FVP and NE were greater at 180 SVP and in adult patients. In addition to a greater impact of baseline BP and age on the initial BP drop and steady-state BP (p<0.01); older age at Fontan repair, lower ventricular ejection fraction and heart rate variability were major determinants of greater BP fluctuation during 180 SVP (p<0.05). Patients with a history of SVT (n=5) exhibited a greater initial BP drop and increase in FVP during 180 SVP (p<0.01). The type of Fontan procedure had no influence on BP dynamics during SVP.

In Fontan patients, wide QRS duration causes a greater hemodynamic fluctuation at slower SVT. Higher baseline BP and age, impaired ventricular function, late Fontan repair and a history of SVT were major determinants of hemodynamic deterioration during faster SVT.