Intraoperative Biventricular Pacing Applications, Techniques, Early Results Vincent A. Gaudiani, MD Luis J. Castro, MD Audrey L. Fisher, MPH Published in The Heart Surgery Forum, Volume 6, Issue 6, 2003.

Traditional Pacing - What Is It? Traditional Pacing Unipolar Pacing – requires a single dipole from the active electrode on the heart to the ground on the skinUnipolar Pacing – requires a single dipole from the active electrode on the heart to the ground on the skin Bipolar Pacing – requires a single dipole from the active electrode on the heart to a ground on the heartBipolar Pacing – requires a single dipole from the active electrode on the heart to a ground on the heart

Biventricular Pacing - What Is It? Biventricular Pacing Requires two dipoles about 180 degrees apart on heart. A dipole from an active electrode on the anterior RV to a ground and a second dipole from an active electrode on the posterolateral LV to a ground.Requires two dipoles about 180 degrees apart on heart. A dipole from an active electrode on the anterior RV to a ground and a second dipole from an active electrode on the posterolateral LV to a ground.

Why Biventricular Pacing? With two dipoles far apart activating the ventricles simultaneously, electrical activation is quicker (90 – 110 ms) than traditional pacing and therefore mechanical activation is more synchronous.With two dipoles far apart activating the ventricles simultaneously, electrical activation is quicker (90 – 110 ms) than traditional pacing and therefore mechanical activation is more synchronous.

Biventricular Pacing Another term for biventricular pacing is cardiac resynchronization therapy (CRT).Another term for biventricular pacing is cardiac resynchronization therapy (CRT).

Biventricular Pacing What are the common clinical examples of suboptimal ventricular synchronization? 1.LBBB 2.Pacemaker Syndrome 3.Some VT’s 4.Any QRS > 130 ms (IVCD’s)

Biventricular Pacing Which patient groups are most likely to suffer reduced cardiac output when poorly synchronized? Patients with a combination of: Large LVIDd’sLarge LVIDd’s QRS > 130 msQRS > 130 ms Low EF’sLow EF’s

Biventricular Pacing What are the clinical consequences of ventricular dyssynchrony? Abnormal septal wall motionAbnormal septal wall motion Reduced dP/dtReduced dP/dt Reduced diastolic filling timeReduced diastolic filling time Prolonged MR durationProlonged MR duration

Cardiac Resynchronization Therapy Cardiac resynchronization in association with an optimized AV delay improves hemodynamic performance by forcing the left ventricle to complete contraction and begin relaxation earlier, allowing an increase in ventricular filling time.Cardiac resynchronization in association with an optimized AV delay improves hemodynamic performance by forcing the left ventricle to complete contraction and begin relaxation earlier, allowing an increase in ventricular filling time. Coordinated activation of the ventricles and septum.Coordinated activation of the ventricles and septum. ECG depicting cardiac resynchronization ECG depicting IVCD

Transvenous ApproachTransvenous Approach –Standard pacing leads in RA and RV –Specially designed left heart lead placed in a left ventricular cardiac vein via the coronary sinus Achieving Cardiac Resynchronization Mechanical Goal: Pace Right and Left Ventricles Cardiac Resynchronization System

Proposed Mechanisms of Cardiac Resynchronization More synchronous left ventricular contraction (towards its own center of mass)More synchronous left ventricular contraction (towards its own center of mass) Improved AV interval optimizationImproved AV interval optimization Mitral valve closure earlier in systoleMitral valve closure earlier in systole

LV Pacing Dobutamine Nelson et al. Circulation 2000;102: CRT Improves Cardiac Function at Diminished Energy Cost p< 0.05

Is Cardiac Resynchronization Pro-arrhythmic? ± ± 20 Ventricular Arrhythmia Duration (min) ± ± 3 PVC Runs NS 3,394 ± 2,970 1,255 ± 1,535 PVC Count P Without CR With CR Sinus Rhythm Group; N=12 Walker, et al. Am J Cardiol 2000;86:231-3.

Randomized Clinical Trials MIRACLEMIRACLE –Multicenter InSync ® Randomized Clinical Evaluation MUSTICMUSTIC –Multisite Stimulation in Cardiomyopathy Data from these trials document symptomatic improvement and increased exercise capacity in patients who have moderate to severe heart failure and ventricular dysynchrony when treated with cardiac resynchronization therapy.

Measurable Outcomes NYHA functional classificationNYHA functional classification Quality of LifeQuality of Life 6-Minute Hall Walk Distance6-Minute Hall Walk Distance Peak VO 2Peak VO 2

Comparison of Clinical Results  8% improvement Peak VO 2  23% improvement 6-Minute Hall Walk  32% improvement Quality of Life Improvement Not assessed NYHA Functional Class MIRACLE ** Trial MUSTIC * Trial * Cazeau S, Leclercq C, Lavergne T, et al. N Engl J Med. 2001; 344: ** Abraham WT, et al. ACC/NASPE 2001 Scientific Sessions. Results not yet published. + Results consistent with MUSTIC trial results

Results of the DAVID Trial 506 patients on maximal medical therapy indicated for ICD506 patients on maximal medical therapy indicated for ICD Randomized to ventricular back-up pacing (40/min) or dual-chamber rate-responsive pacing (70/min)Randomized to ventricular back-up pacing (40/min) or dual-chamber rate-responsive pacing (70/min)

Results of the DAVID Trial Ventricular Backup Pacing 40/min Dual-chamber Rate-responsive 70/min Endpoint: One-year survival free composite time to death or first hospitalization for CHF 83.9% 1-yr free of death or CHF hospitalization Results: *p < 0.03 Conclusion: “Dual-chamber pacing offers no clinical advantage over ventricular backup pacing and may be detrimental by increasing… death or hospitalization for CHF,” for patients with standard indications for ICD therapy, EF<40%, and no indication for bradycardic pacing. 73.3% 1-yr free of death or CHF hospitalization

Results of the COMPANION Trial 1600 patients with active CHF and QRS > 120 ms with maximal medical therapy Endpoint: Combined All-Cause Mortality and All-Cause Hospitalization Biventricular Pacer + ICD Biventricular Pacer Only Medical Therapy Only 0 -20% -40% % Reduction in Mortality +/- Hospitalization

Biventricular Pacing How can biventricular pacing help cardiac surgery patients? Use temporary DDD biventricular pacing in all patients with large LV’s, low EF’s + wide QRS’sUse temporary DDD biventricular pacing in all patients with large LV’s, low EF’s + wide QRS’s Implant permanent LV epicardial electrode in those likely to benefitImplant permanent LV epicardial electrode in those likely to benefit

How To Do Temporary BiV Pacing 1.Sew temporary electrodes to anterior RV and posterolateral LV 2.Attach BOTH to the negative pole of the gray cable 3.Place a skin ground in the positive pole You have now created TWO unipolar pacing dipoles that will activate the RV + LV simultaneously

Temporary BiV Lead Placement

Biventricular Pacing Virtually all cardiac surgery patients with poor LV function who require temporary pacing postoperatively should have temporary biventricular leads as well as atrial leads.Virtually all cardiac surgery patients with poor LV function who require temporary pacing postoperatively should have temporary biventricular leads as well as atrial leads. Who should have a permanent LV lateral electrode placed at the time of operation?Who should have a permanent LV lateral electrode placed at the time of operation?

Biventricular Pacing The following groups may benefit from a posterolateral LV epicardial electrode placed at the time of cardiac operation: Those with pacers already in placeThose with pacers already in place Those with large, hypocontractile LV’s who are likely to need pacingThose with large, hypocontractile LV’s who are likely to need pacing Some Maze patientsSome Maze patients Those who may need ICD’sThose who may need ICD’s

How To Do Permanent BiV Pacing Sew a steroid eluting epicardial pacing wire posterolaterally on all those with large LVIDd and low EF: Who already have pacers in placeWho already have pacers in place Who are likely to need permanent pacingWho are likely to need permanent pacing Leave it buried under clavicleLeave it buried under clavicle

Permanent BiV Lead Placement

How To Do Permanent BiV Pacing Where is the optimal location for the LV wire?

Outcomes

Biventricular Pacing: Preoperative Characteristics (n=25) Mean Age (yrs) 75 NYHA 3+80% Previous MI40% Previous Cardiac Surgery32% Diabetes32% Renal Failure20% Cerebrovascular Disease20% Peripheral Vascular Disease20%

Biventricular Pacing: Intraoperative Characteristics (n=25) Average # Cardiac Procedures 2.2 Concomitant Procedures: CAB56% MVV/R60% AVR/Ao Root Recon48% Maze16% TVV 8% LV Remodel 8% Ascending Ao Recon 8% 36% Double Valves Only 1 patient required IABP

Biventricular Pacing: Intraoperative BiV Pacing - # of Procedures Excluding pacing procedures,Excluding pacing procedures, – (8) pts had one procedure – (9) pts had two procedures – (7) pts had three procedures – (1) pt had five procedures PtsBiV Procedure List 4CAB 1CAB, LVA 2 AVR 1Redo AoRR 1Redo AoRR, ASC Ao 1Redo AVR, MVR 1ARE, MVR 1AoRR, MVV 3AVR, MVV, CAB 1AVR, MVR, CAB, ASC Ao, LVA 1Redo AVR, CAB, ASC Ao 3MVV, CAB, MAZE 1MVV,MAZE 1MVV, CAB 2121 MVV, TVV MVV

Biventricular Pacing: Distribution of LVIDd (n=25)

Biventricular Pacing: Procedural Categories (n=25)

Biventricular Pacing: Preoperative Characteristics Category Average LVEF AverageLVIDd Lead Only (5) 43%5.9 New Pacer (13) 29%6.8 Upgrade (7) 30%5.5 Total (25) 32%6.3

Biventricular Pacing: Patient Characteristics: EF vs. LV Size

NORMAL (QRS<120 ms & LVIDd<5.7 cm) Paced Preop Not Paced Preop Biventricular Pacing: Patient Characteristics: QRS vs. LV Size

Biventricular Pacing: Results 1 operative mortality1 operative mortality 3 late deaths3 late deaths 1 patient had two postop strokes1 patient had two postop strokes 1 patient required subsequent VT ablation1 patient required subsequent VT ablation

Biventricular Pacing: Postoperative Survival (Days)

Surgical Implications of CRT - Overall If we are to improve our knowledge of who will benefit from permanent LV electrodes, we must 1.Renew our interest in preoperative EKG, for instance RBBB v. LBBB 2.Improve our knowledge about intraoperative echo diagnosis of dyssynchrony 3.Learn optimal LV electrode placement

Surgical Implications of CRT – Ischemic MR Because dyssynchrony contributes to “ischemic” MR, we must consider it a correctable part of the syndrome that neither ring nor prosthetic valve placement addresses.Because dyssynchrony contributes to “ischemic” MR, we must consider it a correctable part of the syndrome that neither ring nor prosthetic valve placement addresses. Dyssynchrony tethers the posterior leaflet.Dyssynchrony tethers the posterior leaflet.

Surgical Implications of CRT - LV Remodeling LV aneurysmectomy to physically remodel the heart can no longer be complete unless we “electrically” remodel the heart as well.LV aneurysmectomy to physically remodel the heart can no longer be complete unless we “electrically” remodel the heart as well.

Surgical Implications of CRT - Maze The maze operation in some patients will no longer be complete unless we restore AV synchrony and LV synchrony as wellThe maze operation in some patients will no longer be complete unless we restore AV synchrony and LV synchrony as well

Surgical Implications of CRT - Paced Chronically paced patients with large, hypocontractile hearts who require cardiac operations are easy to upgrade to biventricular pacing and likely to benefitChronically paced patients with large, hypocontractile hearts who require cardiac operations are easy to upgrade to biventricular pacing and likely to benefit

Biventricular Pacing Conclusions We prefer temporary biventricular DDD pacing for postop pacing in all patients with large, low EF heartsWe prefer temporary biventricular DDD pacing for postop pacing in all patients with large, low EF hearts We consider placing a permanent epicardial lead in patients with poor LV function and prolonged QRS who are likely to need permanent pacing or who currently have permanent pacersWe consider placing a permanent epicardial lead in patients with poor LV function and prolonged QRS who are likely to need permanent pacing or who currently have permanent pacers