Electro-energetics of Biventricular, Septal and Conduction System Pacing

Abnormal electrical activation of the ventricles creates abnormalities in cardiac mechanics. Local contraction patterns, as reflected by strain, are not only out of phase, but also show opposing length changes in early and late activated regions. Consequently, the efficiency of cardiac pump function (the amount of stroke work generated by a unit of oxygen consumed), is approximately 30% lower in dyssynchronous than in synchronous hearts. Maintaining good cardiac efficiency appears important for long-term outcomes. Biventricular, left ventricular septal, His bundle and left bundle branch pacing may minimise the amount of pacing-induced dyssynchrony and efficiency loss when compared to conventional right ventricular pacing. An extensive animal study indicates maintenance of mechanical synchrony and efficiency during left ventricular septal pacing and data from a few clinical studies support the idea that this is also the case for left bundle branch pacing and His bundle pacing. This review discusses electro-mechanics and mechano-energetics under the various paced conditions and provides suggestions for future research.

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Prospective evaluation of clinical safety and efficacy of left bundle branch area pacing in comparison with right ventricular sepal pacing

10.21203/rs.3.rs-613528/v1 ◽

2021 ◽

Author(s):

Xing Liu ◽

Wenbin Li ◽

Jianping Zeng ◽

He Huang ◽

Lei Wang ◽

...

Keyword(s):

Right Ventricular ◽

Left Ventricular ◽

Left Ventricular Ejection ◽

Clinical Trial Registry ◽

Clinical Safety ◽

Ventricular Ejection Fraction ◽

Safety And Efficacy ◽

His Bundle ◽

Mechanical Synchrony

Abstract BackgroundLeft bundle branch area pacing (LBBaP) has recently emerged as alternative a new physiologic strategy of pacing to His-bundle pacing (HBP) associated with difficulty of lead implantation, His bundle damage, high and unstable thresholds.ObjectiveThe purpose of this study is to compare clinical safety and efficacy of LBBaP with right ventricular sepal pacing (RVSP).MethodsFrom February 2019 to May 2020, consecutive pacing-indicated patients were prospectively enrolled and divided into two groups. Ventricular synchrony index such as QRS duration (QRSd), interventricular mechanical delay (IVMD) and septal-posterior wall motion delay (SPWMD), left ventricular function such as left ventricular end-diastolic diameter (LVEDD) and left ventricular ejection fraction (LVEF), pacing parameters, and complications were evaluated in perioperative period and during follow-up.ResultsLBBaP was successful in 45 patients (88.2%), and finally 46 patients underwent RVSP. With LBBaP, the ventricular electrical- mechanical synchrony were similar with the native-conduction system (P = .784). However, the ventricular electrical synchrony (QRSd, 108.47 ± 7.64 vs 130.63 ± 13.63 ms, P < .0001) and mechanical synchrony (IVMD, 27.68 ± 4.33 vs 39.88 ± 5.83, P < .0001; SPWMD, 40.39 ± 23.21 vs 96.36 ± 11.55, P < .0001) in the LBBaP group were significantly superior to the RVSP group. No significant differences in LVEDD (46 [44-48.5] vs 47 [44–52] mm, P = .488) and LVEF% (66 [62.5–70] vs 64 [61–68], P = .759) were noted in both two groups at last follow-up. But, in the subgroup analysis, LVEDD was shorter (46 [44–49] vs 50 [47–58] mm, P = .032) and the LVEF% was higher (65 [62–68] vs 63 [58–65], P = .022) in the LBBaP-H (high ventricular pacing ratio > 40%) group compared with RVSP-H group at last follow-up. There was lower capture thresholds (0.59 ± 0.18V vs. 0.71 ± 0.26V, P = 0.011) at implantation in the LBBaP group than RVSP group, and R-wave amplitudes and pacing impedances did not differ between the two groups. No serious complications were found in both two groups at implantation and follow-ups.ConclusionThis study confirms the clinical safety and efficacy of LBBaP, and that produces better ventricular electrical-mechanical synchrony than RVSP. The event of pacing-induced left ventricular dysfunction is lower in the LBBaP-H group than RVSP-H group.Trial registrationTrial registration Chinese Clinical Trial Registry, ChiCTR2100046901, Registered 30 May 2021—Retrospectively registered, http://www.chictr.org.cn/searchproj.aspx?regstatus=1008001.

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Cardiac mechanics

Oxford Textbook of Advanced Critical Care Echocardiography ◽

10.1093/med/9780198749288.003.0004 ◽

2020 ◽

pp. 53-72

Author(s):

Stephen Huang

Keyword(s):

Left Ventricular Pressure ◽

Wall Stress ◽

Cardiac Mechanics ◽

Left Ventricular ◽

Physical Factors ◽

Ventricular Wall ◽

Ventricular Contractility ◽

Intrinsic Properties ◽

Extrinsic Factors ◽

Cardiac Pump Function

Cardiac mechanics involves the study of the mechanical properties of the heart (ventricles) as a pump, and the physical factors that alter these properties. Neurohumoral factors aside, the function of the heart is determined by its intrinsic physical properties as well as extrinsic physical factors. The intrinsic properties include ventricular wall stress, elastance (stiffness) of the ventricle, contractility, and heart rate. The main extrinsic physical factors are blood volume, vessels properties, and extracardiac pressures. This chapter will review these intrinsic properties and how they interact with extrinsic factors to alter the cardiac (pump) function. Neurohumoral factors are excluded in this consideration. LaPlace’s law will be introduced to explain the idea of ventricular wall stress, hence the concepts of preload and afterload. The left ventricular pressure–volume relationship will be reviewed to explain how preload, afterload, and ventricular contractility interact and affect stroke volume. Finally, for completeness, the Frank–Starling relationship and Guyton’s venous return graph will be covered to explain steady state cardiac output.

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Abstract 2162: Mechano-energetic Superiority Of Left Ventricular Apex And Left Ventricular Septal Pacing

Circulation ◽

10.1161/circ.118.suppl_18.s_679 ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Robert W Mills ◽

Larry J Mulligan ◽

Marion Kuiper ◽

Arne van Hunnik ◽

Anniek Lampert ◽

...

Keyword(s):

Coronary Flow ◽

Myocardial Oxygen Consumption ◽

Mechanical Efficiency ◽

Left Ventricular ◽

Stroke Work ◽

Conductance Catheter ◽

Arterial Elastance ◽

Septal Pacing ◽

Effective Arterial Elastance ◽

Cost Figure

Objective: Previous studies showed hemodynamic benefits over right ventricular (RV) apex pacing by left ventricular (LV) septal or LV apex pacing. We investigated whether this benefit is also reflected in mechanical efficiency. Methods: After AV-nodal ablation, dogs received 16 weeks of VDD pacing at the RV apex (RVa; n = 8), LV apex (LVa; n = 7) or LV septum (LVs; n = 8; transventricular-septal approach). After chronic pacing, LV stroke work (SW; conductance catheter) was measured, as well as relative myocardial oxygen consumption (MVO 2 , coronary flow velocity and arterial-coronary sinus O 2 difference). Baseline efficiency (SW/MVO 2 ) was assessed during implant site (IS), RVa, LVa, and RVa + LV lateral (BiV) pacing. In order to investigate the effect of pacing site udner different conditions, measurements were performed during baseline and dobutamine infusion +/− partial aortic occlusion. The O 2 cost of generating SW, corrected for end-systolic elastance and effective arterial elastance, was calculated using the Suga model of mechano-energetics. Results: RVa pacing after chronic LV pacing reduced SW/MVO 2 (Figure a ; mean ± SD, *p<0.05 vs. 1) and increased O 2 cost (Figure b ) in combination with a 12% fall in LV dP/dt-max. However, LVa or BiV pacing after chronic RVa pacing did not significantly alter efficiency, despite a 12% increase in LV dP/dt-max. LVa pacing improved efficiency over LVs and collectively over BiV pacing (p<0.05). Conclusions: Acutely, LVa pacing results in the greatest mechanical efficiency. The lack of improvement in efficiency despite increasing contractility when switching from chronic RVa pacing to LV based pacing may indicate contractile remodeling.

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Feasibility and cardiac synchrony of permanent left bundle branch pacing through the interventricular septum

EP Europace ◽

10.1093/europace/euz188 ◽

2019 ◽

Vol 21 (11) ◽

pp. 1694-1702 ◽

Cited By ~ 45

Author(s):

Xiaofeng Hou ◽

Zhiyong Qian ◽

Yao Wang ◽

Yuanhao Qiu ◽

Xing Chen ◽

...

Keyword(s):

Interventricular Septum ◽

Left Ventricular ◽

Spect Myocardial Perfusion ◽

Septal Pacing ◽

Pacing Lead ◽

Qrs Duration ◽

Mechanical Synchrony ◽

R Wave Amplitude ◽

Normal Cardiac Function

Abstract Aims Left bundle branch pacing (LBBP) recently emerges as a novel pacing modality. We aimed to evaluate the feasibility and cardiac synchrony of permanent LBBP in bradycardia patients. Methods and results Left bundle branch pacing was successfully performed in 56 pacemaker-indicated patients with normal cardiac function. Left bundle branch pacing was achieved by penetrating the interventricular septum (IVS) into the left side sub-endocardium with the pacing lead. His-bundle pacing (HBP) was successfully performed in another 29 patients, 19 of whom had right ventricular septal pacing (RVSP) for backup pacing. The QRS duration, left ventricular (LV) activation time (LVAT), and mechanical synchrony using phase analysis of gated SPECT myocardial perfusion imaging were evaluated. Paced QRS duration in LBBP group was significantly shorter than that in RVSP group (117.8 ± 11.0 ms vs. 158.1 ± 11.1 ms, P < 0.0001) and wider than that in HBP group (99.7 ± 15.6 ms, P < 0.0001). Left bundle branch potential was recorded during procedure in 37 patients (67.3%). Left bundle branch pacing patients with potential had shorter LVAT than those without potential (73.1 ± 11.3 ms vs. 83.2 ± 16.8 ms, P = 0.03). Left bundle branch pacing patients with potential had similar LV mechanical synchrony to those in HBP group. R-wave amplitude and capture threshold of LBBP were 17.0 ± 6.7 mV and 0.5 ± 0.1 V, respectively at implant and remained stable during a mean follow-up of 4.5 months without lead-related complications. Conclusion Permanent LBBP through IVS is safe and feasible in bradycardia patients. Left bundle branch pacing could achieve favourable cardiac electrical and LV mechanical synchrony.

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Novelties in cardiac pacing. Left bundle branch pacing, a step-by-step guide

In a good rythm ◽

10.5604/01.3001.0015.4536 ◽

2021 ◽

Vol 2 (59) ◽

pp. 27-41

Author(s):

Marek Jastrzębski

Keyword(s):

Cardiac Pacing ◽

Left Ventricular ◽

Conduction System ◽

Target Area ◽

His Bundle ◽

His Bundle Pacing ◽

Septal Pacing ◽

Rotation Technique ◽

Ventricular Activity ◽

Pace Mapping

Left bundle branch pacing (LBBP) technique is a new method for conduction system pacing that is useful for both bradyarrhythmia and heart failure indications. LBBP, while less physiological than His bundle pacing, offers several practical advantages. Namely, lower and stable pacing thresholds, good sensing of the intrinsic ventricular activity and easiness in localizing the pacing target. The LBBP method more often than His bundle pacing results in engagement of the conduction system distal to the area of the block. A step-by-step approach to LBBP was described. Attention was given to the following phases of the procedure: 1) localization of the target area on the septum, 2) the lead rotation technique with an interpretation of the lead responses (drill effect, screwdriver effect, entanglement effect), 3) methods for monitoring the lead depth in the septum to avoid perforation (fixation beats, continuous pace mapping, impedance), and 4) methods to differentiate between LBBP and left ventricular septal pacing.

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Physiological (His-bundle or Left Septal) Pacing – Lead Stability Study

Heart Lung and Circulation ◽

10.1016/j.hlc.2021.06.160 ◽

2021 ◽

Vol 30 ◽

pp. S164

Author(s):

C. Chow ◽

P. Crane ◽

H. Lim ◽

U. Mohamed

Keyword(s):

Stability Study ◽

His Bundle ◽

Septal Pacing ◽

Pacing Lead

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Comparing Ventricular Synchrony in Left Bundle Branch and Left Ventricular Septal Pacing in Pacemaker Patients

Journal of Clinical Medicine ◽

10.3390/jcm10040822 ◽

2021 ◽

Vol 10 (4) ◽

pp. 822

Author(s):

Luuk I.B. Heckman ◽

Justin G.L.M. Luermans ◽

Karol Curila ◽

Antonius M.W. Van Stipdonk ◽

Sjoerd Westra ◽

...

Keyword(s):

Left Ventricular ◽

Activation Time ◽

Ventricular Synchrony ◽

Septal Pacing ◽

Ventricular Activation ◽

Qrs Morphology ◽

Conversion Matrix ◽

Qrs Duration ◽

The Right ◽

Electrophysiological Effects

Background: Left bundle branch area pacing (LBBAP) has recently been introduced as a novel physiological pacing strategy. Within LBBAP, distinction is made between left bundle branch pacing (LBBP) and left ventricular septal pacing (LVSP, no left bundle capture). Objective: To investigate acute electrophysiological effects of LBBP and LVSP as compared to intrinsic ventricular conduction. Methods: Fifty patients with normal cardiac function and pacemaker indication for bradycardia underwent LBBAP. Electrocardiography (ECG) characteristics were evaluated during pacing at various depths within the septum: starting at the right ventricular (RV) side of the septum: the last position with QS morphology, the first position with r’ morphology, LVSP and—in patients where left bundle branch (LBB) capture was achieved—LBBP. From the ECG’s QRS duration and QRS morphology in lead V1, the stimulus- left ventricular activation time left ventricular activation time (LVAT) interval were measured. After conversion of the ECG into vectorcardiogram (VCG) (Kors conversion matrix), QRS area and QRS vector in transverse plane (Azimuth) were determined. Results: QRS area significantly decreased from 82 ± 29 µVs during RV septal pacing (RVSP) to 46 ± 12 µVs during LVSP. In the subgroup where LBB capture was achieved (n = 31), QRS area significantly decreased from 46 ± 17 µVs during LVSP to 38 ± 15 µVs during LBBP, while LVAT was not significantly different between LVSP and LBBP. In patients with normal ventricular activation and narrow QRS, QRS area during LBBP was not significantly different from that during intrinsic activation (37 ± 16 vs. 35 ± 19 µVs, respectively). The Azimuth significantly changed from RVSP (−46 ± 33°) to LVSP (19 ± 16°) and LBBP (−22 ± 14°). The Azimuth during both LVSP and LBBP were not significantly different from normal ventricular activation. QRS area and LVAT correlated moderately (Spearman’s R = 0.58). Conclusions: ECG and VCG indices demonstrate that both LVSP and LBBP improve ventricular dyssynchrony considerably as compared to RVSP, to values close to normal ventricular activation. LBBP seems to result in a small, but significant, improvement in ventricular synchrony as compared to LVSP.

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