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Benefits of Cardiac Resynchronization Therapy in an Asynchronous Heart Failure Model Induced by Left Bundle Branch Ablation and Rapid Pacing
Published on: December 11, 2017
Non-contact left ventricular endocardial mapping in cardiac resynchronisation therapy
P D Lambiase1, A Rinaldi, J Hauck
1Department of Cardiology, St Thomas' Hospital, London, UK.
Insights
Cardiac resynchronisation therapy (CRT) failure in heart failure patients may stem from lead placement in slow conduction zones. Optimizing lead position outside these areas significantly improves hemodynamic function.
Area of Science:
- Cardiology
- Electrophysiology
- Medical Devices
Background:
- Up to 30% of heart failure patients do not respond to cardiac resynchronisation therapy (CRT).
- Suboptimal response may be due to coronary sinus lead placement in slow conduction regions, despite current positioning criteria.
- Identifying these slow conduction areas is crucial for improving CRT efficacy.
Purpose of the Study:
- To characterize left ventricular activation using non-contact mapping during CRT.
- To investigate electrophysiological factors influencing optimal left ventricular lead placement.
- To correlate lead position with conduction velocity and hemodynamic outcomes.
Main Methods:
- Non-contact mapping was used in 10 patients with biventricular pacemakers.
- Conduction velocity was measured in regions with and without the coronary sinus lead.
- Hemodynamic parameters (cardiac output, dP/dt(max)) were assessed under different pacing strategies.
Main Results:
- Six patients had leads in slow conduction regions (0.4 m/s vs. 1.8 m/s in normal regions).
- Pacing outside slow conduction areas significantly reduced left ventricular activation time.
- Optimized biventricular pacing improved mean velocity time integral and fusion of depolarization wavefronts.
Conclusions:
- Non-contact mapping effectively identifies slow conduction zones for CRT lead placement.
- Pacing outside identified slow conduction areas leads to significant hemodynamic improvements.
- Failure to achieve CRT benefits may be overcome by repositioning leads away from slow conduction areas.
Background:
Up to 30% of patients with heart failure do not respond to cardiac resynchronisation therapy (CRT). This may reflect placement of the coronary sinus lead in regions of slow conduction despite optimal positioning on current criteria.
Objectives:
To characterise the effect of CRT on left ventricular activation using non-contact mapping and to examine the electrophysiological factors influencing optimal left ventricular lead placement.
Methods:
and results: 10 patients implanted with biventricular pacemakers were studied. In six, the coronary sinus lead was found to be positioned in a region of slow conduction with an average conduction velocity of 0.4 m/s, v 1.8 m/s in normal regions (p < 0.02). Biventricular pacing with the left ventricle paced 32 ms before the right induced the optimal mean velocity time integral and timing for fusion of depolarisation wavefronts from the right and left ventricular pacing sites. Pacing outside regions of slow conduction decreased left ventricular activation time and increased cardiac output and dP/dt(max) significantly.
Conclusions:
In patients undergoing CRT for heart failure, non-contact mapping can identify regions of slow conduction. Significant haemodynamic improvements can occur when the site of left ventricular pacing is outside these slow conduction areas. Failure of CRT to produce clinical benefits may reflect left ventricular lead placement in regions of slow conduction which can be overcome by pacing in more normally activating regions.
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