The Story of Managed Ventricular Pacing

Figure 1:. A: ECG and Marker Channel™ captured in the AAI/R+ mode, MVP™’s predominant operating mode in patients with intact conduction. B: Example showing issuance of a backup ventricular pace following a singular nonconducted atrial event. C: Conversion to a temporary DDD/R mode in the event of high-degree heart block (ie, two of four intervals without a ventricular sense). Not shown is the AAI/R+ restoration method, which involves dropping a ventricular pace periodically and which is deemed successful if a ventricular sense occurs prior to the next atrial event.

Figure 2:. A: ECG/marker strip taken during 1:1 AV pacing at a rate of 120 ppm. Atrial capture verification was complicated by an overlap of atrial pacing and the terminal end of the ventricular paced complex. B: ECG/marker strip taken during 2:1 AV pacing at a rate of 120 ppm. Note that, by liberating isoelectric time, atrial capture assessment on alternating intervals is visually unhampered. C: Sustained ADI pacing in the event of 1:1 AV conduction. Loss of atrial capture (LOAC) is indicated by an abrupt and sustained fallback in heart rate with the appearance of native p-waves on the ECG.

Figure 3:. Simulated failure to detect rapid VT due to long AV delay programming and interference from post-Ap and post-Vp ventricular blanking periods during sensor-driven pacing at 100 bpm and during VT at a rate of 200 bpm. Programmed DDDR, lower rate (LR) =60 bpm, upper sensor rate (USR) = 130 bpm, paced AV (PAV) = 280 ms, tachycardia detection interval (TDI) = 280 ms, and fibrillation detection interval (FDI) = 320 ms (VS markers are not denoted as TS as the above could only be simulated). UR: upper rate.

Figure 4:. Timeline showing the evolution of MVP™ from preconception to final release. FAPTT refers to a facilitated atrial threshold test. Preferred ADI/R was the original name for MVP™. On the left, Dr. Michael O. Sweeney is pictured with the first MVP™ patient during the Gem III DR download study. On the right, David Casavant, Paul Belk, Medtronic founder Earl Bakken, and Tom Mullen are pictured after receiving the Medtronic Patent of Distinction Award, the 12th award granted in Medtronic’s history of more than 65 years recognizing disruptive innovation.