Ann Thorac Surg 2006;82:2292-2294
© 2006 The Society of Thoracic Surgeons
Case Reports
Left Ventricular Pacing Site-Timing Optimization During Biventricular Pacing Using a Multi-Electrode Patch
George Berberian, MDa,
Santos E. Cabreriza, MBAa,
Thomas Alexander Quinn, MSb,
Cara A. Garofalo, MDc,
Henry M. Spotnitz, MDa,*
a Department of Surgery, Columbia University, College of Physicians and Surgeons, New York, New York
b Department of Biomedical Engineering, Columbia University, College of Physicians and Surgeons, New York, New York
c Department of Pediatrics, Columbia University, College of Physicians and Surgeons, New York, New York
Accepted for publication April 27, 2006.
* Address correspondence to Dr Spotnitz, Department of Surgery, Columbia College of Physicians and Surgeons, 622 W 168th St, New York, NY 10032. (Email: hms2{at}columbia.edu).
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Abstract
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A 71-year-old man with class IV congestive heart failure and an infected pacemaker/implantable cardioverter defibrillator (ICD) underwent median sternotomy for removal of endocardial leads with a 15-mm vegetation. Cardiac output during biventricular pacing was optimized with an aortic flow probe, a multi-electrode left ventricular patch, and a randomized protocol assessing 54 combinations of pacing site and right ventricle–left ventricle delay. Results that were assessed with response surface methodology determined permanent epicardial lead position and timing. The difference between the best and worst site-timing combinations altered cardiac index by nearly 70%. This experience demonstrates potential importance of the epicardial approach to site-timing optimization for biventricular pacing.
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Introduction
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Clinical trials have demonstrated that the addition of a left ventricle (LV) pacing lead through the coronary sinus to standard dual chamber mode lead configurations can narrow the QRS duration, improve exercise capacity and quality of life, and reduce mortality in patients with severe heart failure and intraventricular conduction delays [1]. This case report details the relative importance of site and timing in a patient who met current criteria for implementation of biventricular pacing (BiVP).
A 71-year-old man with dilated cardiomyopathy and class IV congestive heart failure was referred for Staphylococcus epidermidis bacteremia. Transesophageal echocardiography revealed a mobile, 15-mm echodensity on the right atrial lead of a dual chamber pacemaker/implantable cardioverter defibrillator (ICD) system. The QRS duration was 220 ms on electrocardiogram. Ejection fraction was estimated at 15% with moderate mitral regurgitation and dyssynchrony of contraction between the interventricular septum and left ventricular free wall.
The patient underwent a median sternotomy with extraction of endocardial pacemaker/ICD leads on cardiopulmonary bypass and removal of the ICD generator. In anticipation of permanent BiVP, temporary BiVP was tested before cardiopulmonary bypass. Mapping of the LV was performed using an aortic flow probe, a multi-electrode patch, and a randomized protocol to identify the optimal lead position and right ventricle–left ventricle delay (RLD) [1–2]. Permanent LV epicardial leads were implanted at the conclusion of the procedure, and temporary leads were used for perioperative BiVP.
Informed consent was obtained by an approved protocol of the institutional review board. The chest was entered through a standard midline sternotomy and a pericardial well was created. The pericardial space was free of adhesions with clear fluid. During anticoagulation, cannulation, and excision of the ICD generator and leads from the chest wall, temporary pacing was established through the right atrial appendage and anterior right ventricle (RV). An epicardial pacing patch incorporating six bipolar pacing leads was placed behind the posterolateral LV and was connected to a temporary pacing unit containing a Medtronic InSync III pacemaker (Medtronic Inc, Minneapolis, MN). A 90-mm electromagnetic flow probe (Carolina Medical Inc, King, NC) was placed around the ascending aorta. Dual chamber mode BiVP was initiated at a heart rate of 90 and an atrioventricular delay of 150 ms. Fifty-four combinations of nine RLDs and six LV sites were tested at 15-second consecutive intervals in a randomized sequence. The LV sites were apex, inferomedial, inferolateral, posterior descending artery, circumflex, and obtuse margin. The RLDs covered a range from 80 ms (right ventricle first pacing) to –80 ms (LV first pacing) in 20 ms increments.
Analog data for electrocardiogram, arterial blood pressure, and aortic flow velocity (Fig 1) were acquired and transferred through a 16 channel analog to digital converter (MacLab, ADInstruments Inc, Milford, MA) to a personal computer (iMac, Apple Computer, Cupertino, CA). Data were then imported into Matlab (The MathWorks, Inc, Natick, MA). Using customized routines, a relatively small number of arrhythmic beats were eliminated. Aortic flow velocity was integrated over each 15-second interval to give cardiac output and was divided by body surface area to give cardiac index. Results were plotted using response surface methodology producing a two-dimensional plot in which percentage change in cardiac index was indicated by color.
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Fig 1. Representative data from Chart 3.6.3/s include cardiac electrocardiogram (EKG) in mV, arterial pressure (AP) in mm Hg, and aortic (Ao) flow velocity in L/min/sec. Transition between two consecutive left ventricular pacing site/right ventricle-left ventricle delay combinations is associated with a sharp drop in arterial pressure and aortic flow velocity. (IL = inferolateral; LVPS = left ventricular pacing site; OM = obtuse margin; RLD = right ventricle–left ventricle delay.)
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Pacing the obtuse margin site at a RLD of –40 or 0 and the circumflex site at a RLD of 0 yielded the highest cardiac index, 64% to 66% greater than the worst combination, pacing the inferolateral site at a RLD of –80. Figure 2
represents a response surface plot of percentage change of cardiac index from each LV site/RLD combination. This plot, constructed retrospectively, allowed greater insight into the effects of BiVP in this patient than was available during real time analysis in the operating room.
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Fig 2. Response surface plot illustrates percentage change in cardiac index for each left ventricular pacing site/right ventricle–left ventricle delay (RLD) combination. Solid black lines indicate a 1% change in cardiac index. (APEX = apical; CIRC = circumflex; IL = inferolateral; IM = inferomedial; LVPS = left ventricular pacing site; OM = obtuse margin; PDA = posterior descending artery.)
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After removal of the infected leads and closure of the atriotomy, permanent epicardial pacing leads were positioned on the LV epicardium directly over the circumflex site on the pacing array. Temporary leads were placed in the right atrial appendage, anterior right ventricle, and circumflex and obtuse margin sites of the LV. The patient was weaned from cardiopulmonary bypass with temporary BiVP and dobutamine and transferred to the intensive care unit. The permanent leads were capped and stored in a subcutaneous pocket in the right upper abdomen. As there was little advantage of a RLD offset, simultaneous BiVP was implemented with a RLD equal to 0 ms.
Biventricular pacing was objectively compared with no pacing on several occasions. On the first postoperative day, cardiac index increased 13% with BiVP. At the time of permanent pacemaker/ICD implantation, initiation of BiVP immediately increased radial artery systolic pressure from 104 to 148 mm Hg. The patient was discharged from the hospital after completion of antibiotic therapy and implantation of a new pacemaker/ICD with BiVP capability.
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Comment
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Recent studies of endocardial BiVP differ in suggesting that cardiac function is maximized by localization of LV pacing leads in the mid-lateral region of the LV [3, 4] or other locations [5, 6]. Endocardial LV lead position is limited by anatomy of the cardiac veins. Furthermore, many locations are unstable or inaccessible, resulting in implantation failure in 5% to 14% of attempts [7, 8]. Consequently, only a limited subset of LV pacing sites has been mapped, and the relative importance of site and timing in BiVP have been inferred but not directly measured. Thoracoscopy has been used to map the epicardial surface of the LV, but randomized study of site and timing has not been previously reported [9].
The surgical procedure described in this report allowed BiVP optimization under an approved protocol of the institutional review board. The effect of posterior, inferior, and lateral LV pacing as well as timing were defined, and a distinct effect of both LV site and RLD on cardiac index was demonstrated.
The hemodynamic benefits of BiVP in this patient were particularly profound. Biventricular pacing is more likely to be effective as ejection fraction decreases and as intraventricular conduction delay, LV dyssynchrony, and mitral regurgitation increase [10]. Our patient’s cardiomyopathy was relatively advanced in all of these respects. The precise mechanism of benefit in this patient may include restoration of synchronous contraction of the free wall and septum, reduction of mitral regurgitation, or both. Most importantly, we do not know whether the profound benefit experienced by this patient reflects the advanced nature of his cardiomyopathy or mapping of the optimal site-timing relation. However, it is clear that additional studies in this area are needed and that the question of how to best optimize clinical results of BiVP may need further attention.
Despite limitations, this is the first clinical report of the relative importance of site and timing in BiVP. Results indicate that BiVP optimization can increase cardiac output by 66% when best and worst pacing protocols are compared and provide a rational basis for additional studies aimed at maximizing the clinical response to pacing for heart failure.
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Acknowledgments
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Supported in part by the National Heart, Lung and Blood Institute of the National Institutes of Health (RO1 HL 48109 to Dr Spotnitz) and in part by the Department of Surgery, Columbia University College of Physicians and Surgeons, New York, NY.
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References
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- Cazeau S, Leclercq C, Lavergne T, et al. Effects of multi-site biventricular pacing in patients with heart failure and intraventricular conduction delay N Eng J Med 2001;344:873-880.[Abstract/Free Full Text]
- Dekker LAJ, Phelps B, Dijkman B, et al. Epicardial left ventricular lead placement for cardiac resynchronization therapy: Optimal pace site selection with pressure-volume loops J Thoracic Cardiovasc Surg 2004;127:1641-1647.[Abstract/Free Full Text]
- Auricchio A, Klein H, Tockman B, et al. Transvenous biventricular pacing for heart failure: can the obstacles be oversome? Am J Cardiol 1999;83:136D-142D.[Medline]
- Butter C, Auricchio A, Stellbrink C, et al. Should stimulation site be tailored in the individual heart failure patient? Am J Cardiol 2000;86:K144-K151.[Medline]
- Pappone C, Rosanio S, Oreto G, et al. Cardiac pacing in heart failure patients with left bundle branch block: impact of pacing site for optimizing left ventricular resynchronization Ital Heart J 2000;1:464-469.[Medline]
- Ansalone G, Giannantoni P, Ricci R, Trambaiolo P, Fedele F, Santini M. Doppler myocardial imaging to evaluate the effectiveness of pacing sites in patients receiving biventricular pacing J Am Coll Cardiol 2002;39:489-499.[Abstract/Free Full Text]
- Alonso C, Leclercq C, d’Allonnes FR, et al. Six year experience of transvenous left ventricular lead implantation for permanent biventricular pacing in patients with advanced heart failure: technical aspects Heart 2001;86:405-410.[Abstract/Free Full Text]
- Valls-Bertault V, Mansourati J, Gilard M, Etienne Y, Munier S, Blanc JJ. Adverse events with transvenous left ventricular pacing in patients with severe heart failure: early experience from a single centre Europace 2001;3:60-63.[Abstract/Free Full Text]
- Maessen JG, Phelps B, Dekker LAJ, Dijkman B. Minimal invasive epicardial lead implantation: optimizing cardiac resynchronization with a new mapping device for epicardial lead placement Eur J Cardiothorac Surg 2004;25:894-896.[Abstract/Free Full Text]
- Abraham WT. Cardiac resynchronization therapy: a review of clinical trials and criteria for identifying the appropriate patient Rev Cardiovasc Med 2003;4:S30-S37.
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Abstract
Introduction
