The Lewis Lead for Detection of Ventriculoatrial Conduction Type

First-in-human noninvasive left ventricular ultrasound pacing: A potential screening tool for cardiac resynchronization therapy

Background

A screening tool to predict response to cardiac resynchronization therapy (CRT) could improve patient selection and outcomes.

Objective

The purpose of this study was to investigate the feasibility and safety of noninvasive CRT via transcutaneous ultrasonic left ventricular (LV) pacing applied as a screening test before CRT implants.

Methods

P-wave-triggered ultrasound stimuli were delivered during bolus dosing of an echocardiographic contrast agent to simulate CRT noninvasively. Ultrasound pacing was delivered at a variety of LV locations with a range of atrioventricular delays to achieve fusion with intrinsic ventricular activation. Three-dimensional cardiac activation maps were acquired via the Medtronic CardioInsight 252-electrode mapping vest during baseline, ultrasound pacing, and after CRT implantation. A separate control group received only the CRT implants.

Results

Ultrasound pacing was achieved in 10 patients with a mean of 81.2 ± 50.8 ultrasound paced beats per patient and up to 20 consecutive beats of ultrasound pacing. QRS width at baseline (168.2 ± 17.8 ms) decreased significantly to 117.3 ± 21.5 ms (P <.001) in the best ultrasound paced beat and to 125.8 ± 13.3 ms (P <.001) in the best CRT beat. Electrical activation patterns were similar between CRT pacing and ultrasound pacing with stimulation from the same area of the LV. Troponin results were similar between the ultrasound pacing and the control groups (P = .96), confirming safety.

Conclusion

Noninvasive ultrasound pacing before CRT is safe and feasible, and it estimates the degree of electrical resynchronization achievable with CRT. Further study of this promising technique to guide CRT patient selection is warranted.

ECG monitoring leads and special leads

ECG monitoring is common place in the hospital and even pre-hospital setting. The need for different types of lead systems in different settings has been emphasised. Simple three electrode bipolar recording is ubiquitous for monitoring. This can be used to record modified bipolar chest leads as well. Using five leads gives the option of getting a chest lead in addition to bipolar limb leads, enhancing detection of ischemia during procedures. Lead stability is important when the movement of the subject is maximum as in exercise testing. Mason-Likar modification with limb leads shifted to the torso is popular for exercise testing, though the diagnostic value of the ECG is altered. Lund system with leads on proximal part of limbs have both stability and fair diagnostic value. EASI lead system permits derivation of 12 leads from just five electrodes. Lewis lead and the newly devised modified limb lead system are useful in enhancing detection of atrial activity. Fontaine lead has been designed to improve visualization of Epsilon wave in arrhythmogenic right ventricular dysplasia.