Cardiac Contractility Modulation: A Technical Review

Figures

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  Figure 1:. Optimizer Smart™ implantable pulse generator and Mini Charger™. Images courtesy of Impulse Dynamics.

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  Figure 2:. Chest radiograph of a cardiac contractility modulation (CCM) implant. Displayed are (A) a 3-lead CCM system only, (B) a 2-lead CCM system only, and (C) a 2-lead CCM system with a dual-chamber implantable cardioverter-defibrillator. Of note, the designation of the septal CCM leads as “LS” and “RV” is not determined by location, but rather the differential timing of sensing on each lead at implant. Abbreviations: CCM, cardiac contractility modulation; ICD, implantable cardioverter-defibrillator; IPG, implanted pulse generator; LS, local sense; RA, right atrial; RAI, right atrial ICD; RV, right ventricular; RVI, right ventricular implantable cardioverter-defibrillator.

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  Figure 3:. The OMNI™ II programmer system (A) and boot-up (B) and main screens (C). (B, C) Images courtesy of Impulse Dynamics.

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  Figure 4:. Cardiac contractility modulation (CCM) timing for OVO and ODO modes. OVO mode timing is shown in panels A–E. Additional criteria for ODO function are displayed in panel F. A: A V channel sense (“time zero”) begins the process and opens the local sense alert window (LSAW). B: An LS channel sense closes the LSAW and triggers the LS-CCM delay. C: CCM therapy delivers at the end of the LS-CCM delay absent an additional LS channel sense. Normal programmed timing variants may occur with an LSAW beginning a short time after D: or before E: an RV channel sense. E: The implantable pulse generator looks back from time zero for an LS channel sense that occurs earlier in time, but within the LSAW, to trigger an LS-CCM delay. The LS-CCM delay is adjusted in both variants (D and E) to time the CCM pulse properly. F: Atrial sensing within the long and short atrioventricular windows is required after an RV channel sense to initiate the LSAW in the ODO mode. Only following atrial sensing in this window does the process continue as seen in A–C. Otherwise, CCM is not delivered for that beat. Abbreviations: A, atrial; AV, atrioventricular; CCM, cardiac contractility modulation; IPG, implantable…

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  Figure 5:. Twelve-lead electrocardiogram with cardiac contractility modulation (CCM) in the OVO mode. The implantable pulse generator recognizes the seventh beat as a premature ventricular contraction under the upper rate limit of 110 bpm (red arrow), inhibiting CCM therapy. The post-inhibition response is programmed to “0” indicated by CCM being delivered with the next atrial paced and conducted beat (black arrow).

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  Figure 6:. Anteroposterior and 40° left anterior oblique fluoroscopic ventricular lead positions during cardiac contractility modulation (CCM) implant. The implantable cardioverter-defibrillator lead was previously implanted high in the outflow tract. The initial CCM ventricular lead positions show dyssynchronous movement, and the tips move apart with beating (A and B). Repositioning the ventricular leads results in tandem movement without tip separation (C and D). The superior CCM lead is felt to be appropriately distanced from the base of the heart. See Videos 2A–2D for more information.

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  Figure 7:. Native signal undersensing from cardiac contractility modulation (CCM) before ventricular fibrillation (VF) induction. The single-chamber defibrillator has a non-programmable ventricular blanking period. The red arrows indicate the undersensed native signals on the near-field ventricular electrogram. The automatic gain function results in only CCM signal sensing by the defibrillator initially (black arrows). CCM therapy is immediately inhibited with induction and remains inhibited during VF. VF detection is not delayed nor is VF undersensed.

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  Figure 8:. LS scan test and LS setup on the OMNI™ II Programmer. A: LS channel signals measured with repeat sampling at 0.3–1.7 mV (blue histograms) and with respect to right ventricular (RV) channel sensing (time zero) after the “Automatic Scan” button is selected. More sensitive settings detect signals that are not specific for the near-field LS pacemaker lead and sense the single local beat multiple times. The scan suggests an LS channel sensitivity of 1.7 mV for programming. B: The display when “Go to LS setup” is chosen. The LS channel sensitivity, refractory periods, local sense alert window (LSAW), and LS-CCM delay are programmed here. The LSAW begins +6 ms after V channel sensing and extends out to +36 ms from time zero. The LSAW (yellow) and LS-CCM delay (blue) windows are shown in a linear timeline at the top of the panel. Images courtesy of Impulse Dynamics.