Physiologic Pacing: The Next Frontier
Nov 11 2022 | Medicover Hospitals | Hyderabad - Hi-tech City
Permanent pacemakers represent an important therapy for patients with severe bradyarrhythmia. Conventionally, ventricular pacing is performed by implanting the lead in the right ventricle (RV), at the apex or septum. This abnormally activates the ventricles, leads to desynchrony of contraction, and can cause left ventricular systolic dysfunction and heart failure in the long run. The newer technique of conduction system pacing (CSP) aims to use the heart’s native conduction system to deliver pacing so that the ventricles are activated in a manner that is closely similar to their usual pattern of activation.
This provides a physiologic form of pacing and yields better long-term outcomes compared to conventional RV pacing. CSP can be performed by either His bundle pacing or left bundle branch area pacing (LBBP) and requires specialized technique and skill on the part of the operator. In this article, two cases of LBBP carried out at Medicover Hospitals, Hitech City is described.
A 62-year-old female diabetic, hypertensive presented with dyspnoea on exertion, fatigue, and dizziness. ECG showed a complete heart block (CHB) with a narrow QRS escape rhythm (Figure 3A). An echocardiogram showed normal LV systolic function. 3A: ECG showing complete heart block with narrow QRS escape. 3B: ECG after left bundle branch pacing showing narrow paced QRS,almost identical to the original native QRS.
The patient was taken up for dual-chamber permanent pacemaker implantation to perform CSP. A quadripolar electrophysiology diagnostic catheter was placed from the femoral route in the His location to have a ﬂuoroscopic landmark to guide the positioning of the ventricular lead. Using a Medtronic 3830 lead (Medtronic Parkway, Minneapolis, MN, USA) and a C315 His sheath (Medtronic limited, Croxley Park, Hatters Lane, Building 9, UK/Ireland). His Bundle pacing was ﬁrst attempted; however, due to an abnormally high location of the His, satisfactory lead stability could not be obtained.
Hence, the strategy was switched to LBBP. Using the same sheath and lead, the correct location in the interventricular septum was reached, guided by the location of the His catheter and QRS morphology on pacing through the lead. Then, ﬁve to six rapid turns with the lead were given to penetrate the interventricular septum. Using careful analysis of multiple parameters such as QRS morphology, lead impedance, measurement of activation times, and mapping of potentials, additional turns were given to position the lead at the right depth in the IVS to achieve optimal LB capture.Excessive penetration risks perforation into the LV cavity. After conﬁrming excellent LB capture parameters, the delivery sheath was slit, and lead secured.