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441 Targeted Cardiac Resynchronization Therapy Using MRI-Based 3-Dimensional Cardiac Models: A Pilot Feasibility Study
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and heart rate responses, electrocardiographic recordings, and oxygen saturation measurement among participants who pedaled against a ramp protocol based on body weight. All participants exercised to exhaustion. Six patients with incomplete data were excluded from analysis. RESULTS: Peak systolic and diastolic blood pressures were significantly different among the two groups, with higher values obtained supine. Maximum VO2 (VO2 ⫽ maximum oxygen uptake, mL/ min), VO2 at anaerobic threshold, and VO2 at RER1 (respiratory exchange ratio) were significantly higher in the upright position. CONCLUSIONS: Higher VO2 at anaerobic threshold, VO2 at RER1, and maximum VO2 in the upright position during graded exercise is supported by some literature, although this is the first large pediatric study to demonstrate this. Several physiologic mechanisms have been proposed. Increased blood flow and higher perfusion pressures to the leg muscles in the upright position, as well as better mechanical efficiency may allow improved performance. Also the involvement of relatively less muscle mass, and unfamiliarity with cycling in the recumbent position may contribute.
Canadian Journal of Cardiology Volume 28 2012
anatomy is variable and may be affected by dilatation of cardiac chambers. The purpose of this randomized pilot study was to determine the role of pre procedural multidetector coronary sinus CT Scan and its impact on coronary sinus lead implantation success rate in patients receiving CRT. METHODS: A randomized pilot study including 40 patients referred for CRT-ICD, were randomized to either MDCT guided CRT-implant group or the standard CRT implant (control group). 18 patients underwent MDCT for imaging and 3D reconstruction of the coronary sinus and tributary veins. See table 1. RESULTS: See figure 1 CONCLUSION: This pilot feasibility study demonstrated that coronary sinus anatomy can be defined in detail using MDCT. No advantages with MDCT regarding LV lead positioning were observed. Further research is needed to determine the role of preprocedural MDCT in patients undergoing CRT-ICD implantation.
Canadian Cardiovascular Society (CCS) CCS186 Oral CARDIAC RESYNCHRONIZATION THERAPY Monday, October 29, 2012 440 ROLE OF PRE-PROCEDURAL MULTIDETECTOR CARDIAC CT SCAN IN LEFT VENTRICULAR LEAD PLACEMENT IN CARDIAC RESYNCHRONIZATION THERAPY (CRT): A PILOT STUDY
441 TARGETED CARDIAC RESYNCHRONIZATION THERAPY USING MRI-BASED 3-DIMENSIONAL CARDIAC MODELS: A PILOT FEASIBILITY STUDY J Stirrat, R Yee, A Krahn, L Gula, P Leong-Sit, GJ Klein, D Scholl, A Goela, M Drangova, JA White
JA Palazzolo, M Ellins, M Valenza, P Nery, JS Healey, GM Nair, W Meyer, V Malcolm, CA Morillo
London, Ontario
Hamilton, Ontario
BACKGROUND: Cardiac resynchronization therapy (CRT) aims
Cardiac Resynchronization Therapy (CRT) has become a standard therapy in patients with refractory heart failure. Acute procedure success is determined by appropriate placement of the left ventricular lead in the coronary sinus. Coronary sinus
to reduce dyssynchronous contraction through simultaneous pacing of the right ventricular (RV) septum and left ventricular (LV) lateral wall. Up to 40% of patients do not respond, largely attributed to lack of dyssynchrony and/or transmural scar at
BACKGROUND:
S265
Abstracts
pacing sites. In this pilot study we tested the feasibility of guiding LV and RV leads to “optimal” segmental targets using a MRI-based 3D surface rendered cardiac model. METHODS: Twenty-two consecutive patients planned for CRT were recruited. All patients underwent cardiac MRI inclusive of cine and delayed enhancement (DE) imaging using a 3T scanner. A blinded interpreter determined the time to maximal radial wall thickening (TmWT) and myocardial scar burden for each of 16 myocardial segments. All potential LV lead segmental targets were ranked, first according to scar burden (lowest first) and then by TmWT (highest first). All potential RV lead segmental targets were also ranked according to scar burden (lowest first). These rankings were encoded onto a surface rendered cardiac model, displayed in standard fluoroscopic views (Figure 1A) and used intraprocedurally to direct lead placement using fluoroscopy. A cardiac gated CT was then performed at 1-month (Figure 1B) to assess procedural success for target achievement. RESULTS: Mean age and LVEF were 64.7 ⫾ 8.2 years and 25.7 ⫾ 7.9%, with a mean NYHA class of 2.8 ⫾ 0.5. Planned LV and RV pacing sites differed from conventional siting (basal posterolateral segment and RV apex) in 17 and 5 patients, respectively. All patients successfully underwent CRT device implantation with a mean fluoroscopy time of 26 ⫾ 17 minutes, and a mean procedure time of 152.0 ⫾ 40.1 minutes. CT imaging showed LV and RV leads to be successfully delivered to the planned or immediately adjacent segment in 86.3% and 90.9% of patients, respectively. Two patients had complications; a small pericardial effusion in a patient that was prescribed conventional lead positioning by the model, and a lead dislodgement in a patient prescribed unconventional LV lead placement (Basal anterior segment). CONCLUSION: In this pilot study we demonstrate that a targeted approach to CRT lead placement using an MRI-based cardiac model is clinically feasible. A prospective clinical trial evaluating the clinical benefit of this approach is planned.
442 QUADRIPOLAR LV LEAD PROVIDES PHRENIC NERVE STIMULATION AVOIDANCE F Philippon, F Molin, WH Fung, J Deharo, F Anselme, PP Delnoy, H Crijns, C Morillo, F Maru, A Krahn, J Delumeau, L Liu, K Gutleben Ste-Foy, Québec
Placement of an LV lead is often constrained by phrenic nerve stimulation (PNS). To address the challenge, the Left Ventricular Lead Acute Clinical Study (LILAC) was conducted to evaluate the ability of a new investigational quadripolar LV lead to map the PNS occurrence and mitigate it with single lead insertion at implant using multipolar configurations. This non-randomized study was conducted at 9 international centers and enrolled 54 patients indicated for CRT implantation. METHODS: The lead design tested was intended to provide electrode contact in two different LV zones simultaneously (mid-apex (MA) and mid-base (MB)). Two lead models with short (S) and long (L) electrode spacing were included to provide the implanter with the ability to select an electrode spacing that matched the patient’s individual anatomy. After acquiring a venogram, the implanter tested 1 or 2 lead models by wedging the lead in a selected target vein and recorded the lead testing positions via fluoro images. Unipolar pacing thresholds (PT) and PNS thresholds at each electrode were collected. RESULTS: Fifty patients were tested successfully with additional 2 attempts and 2 intents. The PNS occurrence and threshold are summarized in Table 1. By basing lead selection on individual venograms (no repositioning of the lead), 90% of cases demonstrated that at least one electrode in either zone had a PT ⱕ 2.5V without PNS. In addition, 70% of patients achieved dual zone stimulation with a PT of ⱕ 2.5V without PNS in MB and MA zones simultaneously. Mean thresholds from the best electrodes in MB and MA zones were 1.7⫾1.4V vs. 1.6⫾1.6V (p⫽ns) accordingly. Of the 24 patients with PNS, electrode switching resulted in no PNS in 20 patients at a PT of ⱕ 2.5V and in 23 patients at ⱕ 3.5V with unipolar pacing configuration only. CONCLUSION: The LILAC quadripolar mapping data suggests PNS mostly occur in MA region with low stimulation threshold compared to MB region. Using this family of quadripolar leads, implanters would be able to achieve low PT and PNS avoidance at either MA or MB zone without repositioning the lead at implant. BACKGROUND:
443 LEARNING FROM THE BEST: A CASE SERIES EXAMINATION OF TWENTY “SUPER-RESPONDERS” TO CARDIAC RESYNCHRONIZATION THERAPY A Wassef, R Yee, J Wong, D Scholl, L Gula, D McCarty, A Krahn, A Skanes, P Leong-Sit, A Goela, A Islam, G Klein, M Drangova, J White HSF Clinician Scientist Award, HSF Grant in Aid, POEM
London, Ontario
and heart rate responses, electrocardiographic recordings, and oxygen saturation measurement among participants who pedaled against a ramp protocol based on body weight. All participants exercised to exhaustion. Six patients with incomplete data were excluded from analysis. RESULTS: Peak systolic and diastolic blood pressures were significantly different among the two groups, with higher values obtained supine. Maximum VO2 (VO2 ⫽ maximum oxygen uptake, mL/ min), VO2 at anaerobic threshold, and VO2 at RER1 (respiratory exchange ratio) were significantly higher in the upright position. CONCLUSIONS: Higher VO2 at anaerobic threshold, VO2 at RER1, and maximum VO2 in the upright position during graded exercise is supported by some literature, although this is the first large pediatric study to demonstrate this. Several physiologic mechanisms have been proposed. Increased blood flow and higher perfusion pressures to the leg muscles in the upright position, as well as better mechanical efficiency may allow improved performance. Also the involvement of relatively less muscle mass, and unfamiliarity with cycling in the recumbent position may contribute.
Canadian Journal of Cardiology Volume 28 2012
anatomy is variable and may be affected by dilatation of cardiac chambers. The purpose of this randomized pilot study was to determine the role of pre procedural multidetector coronary sinus CT Scan and its impact on coronary sinus lead implantation success rate in patients receiving CRT. METHODS: A randomized pilot study including 40 patients referred for CRT-ICD, were randomized to either MDCT guided CRT-implant group or the standard CRT implant (control group). 18 patients underwent MDCT for imaging and 3D reconstruction of the coronary sinus and tributary veins. See table 1. RESULTS: See figure 1 CONCLUSION: This pilot feasibility study demonstrated that coronary sinus anatomy can be defined in detail using MDCT. No advantages with MDCT regarding LV lead positioning were observed. Further research is needed to determine the role of preprocedural MDCT in patients undergoing CRT-ICD implantation.
Canadian Cardiovascular Society (CCS) CCS186 Oral CARDIAC RESYNCHRONIZATION THERAPY Monday, October 29, 2012 440 ROLE OF PRE-PROCEDURAL MULTIDETECTOR CARDIAC CT SCAN IN LEFT VENTRICULAR LEAD PLACEMENT IN CARDIAC RESYNCHRONIZATION THERAPY (CRT): A PILOT STUDY
441 TARGETED CARDIAC RESYNCHRONIZATION THERAPY USING MRI-BASED 3-DIMENSIONAL CARDIAC MODELS: A PILOT FEASIBILITY STUDY J Stirrat, R Yee, A Krahn, L Gula, P Leong-Sit, GJ Klein, D Scholl, A Goela, M Drangova, JA White
JA Palazzolo, M Ellins, M Valenza, P Nery, JS Healey, GM Nair, W Meyer, V Malcolm, CA Morillo
London, Ontario
Hamilton, Ontario
BACKGROUND: Cardiac resynchronization therapy (CRT) aims
Cardiac Resynchronization Therapy (CRT) has become a standard therapy in patients with refractory heart failure. Acute procedure success is determined by appropriate placement of the left ventricular lead in the coronary sinus. Coronary sinus
to reduce dyssynchronous contraction through simultaneous pacing of the right ventricular (RV) septum and left ventricular (LV) lateral wall. Up to 40% of patients do not respond, largely attributed to lack of dyssynchrony and/or transmural scar at
BACKGROUND:
S265
Abstracts
pacing sites. In this pilot study we tested the feasibility of guiding LV and RV leads to “optimal” segmental targets using a MRI-based 3D surface rendered cardiac model. METHODS: Twenty-two consecutive patients planned for CRT were recruited. All patients underwent cardiac MRI inclusive of cine and delayed enhancement (DE) imaging using a 3T scanner. A blinded interpreter determined the time to maximal radial wall thickening (TmWT) and myocardial scar burden for each of 16 myocardial segments. All potential LV lead segmental targets were ranked, first according to scar burden (lowest first) and then by TmWT (highest first). All potential RV lead segmental targets were also ranked according to scar burden (lowest first). These rankings were encoded onto a surface rendered cardiac model, displayed in standard fluoroscopic views (Figure 1A) and used intraprocedurally to direct lead placement using fluoroscopy. A cardiac gated CT was then performed at 1-month (Figure 1B) to assess procedural success for target achievement. RESULTS: Mean age and LVEF were 64.7 ⫾ 8.2 years and 25.7 ⫾ 7.9%, with a mean NYHA class of 2.8 ⫾ 0.5. Planned LV and RV pacing sites differed from conventional siting (basal posterolateral segment and RV apex) in 17 and 5 patients, respectively. All patients successfully underwent CRT device implantation with a mean fluoroscopy time of 26 ⫾ 17 minutes, and a mean procedure time of 152.0 ⫾ 40.1 minutes. CT imaging showed LV and RV leads to be successfully delivered to the planned or immediately adjacent segment in 86.3% and 90.9% of patients, respectively. Two patients had complications; a small pericardial effusion in a patient that was prescribed conventional lead positioning by the model, and a lead dislodgement in a patient prescribed unconventional LV lead placement (Basal anterior segment). CONCLUSION: In this pilot study we demonstrate that a targeted approach to CRT lead placement using an MRI-based cardiac model is clinically feasible. A prospective clinical trial evaluating the clinical benefit of this approach is planned.
442 QUADRIPOLAR LV LEAD PROVIDES PHRENIC NERVE STIMULATION AVOIDANCE F Philippon, F Molin, WH Fung, J Deharo, F Anselme, PP Delnoy, H Crijns, C Morillo, F Maru, A Krahn, J Delumeau, L Liu, K Gutleben Ste-Foy, Québec
Placement of an LV lead is often constrained by phrenic nerve stimulation (PNS). To address the challenge, the Left Ventricular Lead Acute Clinical Study (LILAC) was conducted to evaluate the ability of a new investigational quadripolar LV lead to map the PNS occurrence and mitigate it with single lead insertion at implant using multipolar configurations. This non-randomized study was conducted at 9 international centers and enrolled 54 patients indicated for CRT implantation. METHODS: The lead design tested was intended to provide electrode contact in two different LV zones simultaneously (mid-apex (MA) and mid-base (MB)). Two lead models with short (S) and long (L) electrode spacing were included to provide the implanter with the ability to select an electrode spacing that matched the patient’s individual anatomy. After acquiring a venogram, the implanter tested 1 or 2 lead models by wedging the lead in a selected target vein and recorded the lead testing positions via fluoro images. Unipolar pacing thresholds (PT) and PNS thresholds at each electrode were collected. RESULTS: Fifty patients were tested successfully with additional 2 attempts and 2 intents. The PNS occurrence and threshold are summarized in Table 1. By basing lead selection on individual venograms (no repositioning of the lead), 90% of cases demonstrated that at least one electrode in either zone had a PT ⱕ 2.5V without PNS. In addition, 70% of patients achieved dual zone stimulation with a PT of ⱕ 2.5V without PNS in MB and MA zones simultaneously. Mean thresholds from the best electrodes in MB and MA zones were 1.7⫾1.4V vs. 1.6⫾1.6V (p⫽ns) accordingly. Of the 24 patients with PNS, electrode switching resulted in no PNS in 20 patients at a PT of ⱕ 2.5V and in 23 patients at ⱕ 3.5V with unipolar pacing configuration only. CONCLUSION: The LILAC quadripolar mapping data suggests PNS mostly occur in MA region with low stimulation threshold compared to MB region. Using this family of quadripolar leads, implanters would be able to achieve low PT and PNS avoidance at either MA or MB zone without repositioning the lead at implant. BACKGROUND:
443 LEARNING FROM THE BEST: A CASE SERIES EXAMINATION OF TWENTY “SUPER-RESPONDERS” TO CARDIAC RESYNCHRONIZATION THERAPY A Wassef, R Yee, J Wong, D Scholl, L Gula, D McCarty, A Krahn, A Skanes, P Leong-Sit, A Goela, A Islam, G Klein, M Drangova, J White HSF Clinician Scientist Award, HSF Grant in Aid, POEM
London, Ontario