From the Guidelines
Ventricular tachycardia (VT) management should prioritize optimization of underlying hemodynamic status, identification of potentially treatable residual hemodynamic problems, and careful evaluation of ventricular function, as indicated by the 2017 AHA/ACC/HRS guideline 1. When managing VT, it is crucial to consider the correlation between residual hemodynamic abnormalities and the risk of ventricular arrhythmias, particularly in patients with repaired tetralogy of Fallot (TOF) or other forms of congenital heart disease. Key factors to evaluate include right ventricular (RV) hypertension, residual pulmonary outflow tract obstruction or regurgitation, and RV dilation, as these have been identified as risk factors for VT and sudden cardiac death (SCD) 1. Some essential steps in managing VT include:
- Careful evaluation of hemodynamic status to identify potentially treatable residual problems, such as outflow tract stenosis or significant regurgitation, which may benefit from catheter or surgical intervention 1.
- Assessment of ventricular function, including exercise testing to evaluate functional capacity, as presentation with frequent or complex ventricular arrhythmias may indicate worsening hemodynamic function 1.
- Consideration of a combined approach of surgery for structural abnormalities with map-guided arrhythmia surgery for patients with repaired TOF or other forms of congenital heart disease, although this approach may have limitations due to the deep endocardial or left ventricular origin of VT 1. Overall, the management of VT should focus on addressing the underlying hemodynamic and structural issues contributing to the arrhythmia, with the goal of reducing the risk of SCD and improving quality of life for patients with ventricular arrhythmias.
From the Research
Tidal Volume and Ventilator Settings
- The use of high tidal volumes in mechanical ventilation has been associated with increased mortality in patients with congestive heart failure and post cardiac arrest 2.
- A study found that mechanical ventilation with high tidal volumes was associated with increased mortality in patients with congestive heart failure and post cardiac arrest, with an odds ratio for death of 9.0 (95% CI: 1.3-62.0, P = 0.03) with VT/PBW above the median 2.
- Another study found that a low tidal volume strategy did not result in a greater number of ventilator-free days than an intermediate tidal volume strategy in patients in the ICU without ARDS 3.
Respiratory Mechanics and Ventilator-Derived Parameters
- Ventilator-derived parameters such as intrinsic PEEP, peak and plateau pressures, driving pressure, transpulmonary pressure, mechanical energy, and mechanical power should be strictly monitored at bedside to develop a personalized approach to mechanical ventilation 4.
- The pressure generated 100 ms after onset of inspiratory effort (P0.1) and the pressure-time product per minute (PTP/min) should also be evaluated during assisted mechanical ventilation 4.
Tidal Volume and Inspiratory Effort
- Higher tidal volume per predicted body weight and heart rate at the end of a sweep gas-off trial were significantly associated with increased odds of unsafe liberation from VV-ECMO 5.
- Patients who had unsafe liberation from VV-ECMO also had significantly higher inspiratory efforts (esophageal pressure swings) and worse outcomes (longer MV duration, ICU and hospital length of stay) 5.
Pulse Pressure Variation and Fluid Responsiveness
- Pulse pressure variation (PPV) is a well-established method for predicting fluid responsiveness in mechanically ventilated patients, but its predictive accuracy is disputed for ventilation with low tidal volume or low heart-rate-to-respiratory-rate ratio 6.
- The effects of VT and RR on PPV and on PPV's ability to predict fluid responsiveness were investigated, and it was found that both PPV measures were nearly proportional to VT, and higher RR was associated with lower PPV 6.