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The Effect of Atrial-Ventricular and Interventricular Delays on Gas Exchange during Excercise
The 16th Annual Scientific Meeting
HFSA
S55
CRT, the improvement of LVEF, LVESD, PASP and mitral regurgitation were comparable in 3 groups (PO.05). The survival estimate was the best in class I-II group and the worst in class IV group (P!.001, figure). Univariate and multivariate analysis showed that left bundle branch block (HR 0.73, CI 0.58-0.93, P5.012), age per 10 years (HR 1.43, CI 1.25-1.64, P!.001), ischemic cardiomyopathy (HR 1.70, CI 1.29-2.23, P!.001) and NYHA class IV (HR 2.48, CI 1.35-4.55, P5.003) were independent predictors for mortality. Conclusions: Patients with mild to moderate HF symptoms achieve comparable benefit from CRT in improving LV systolic function and reverse remodeling as in severe HF groups. However, NYHA functional class remains an independent predictor for all-cause mortality.
176 The Effect of Atrial-Ventricular and Interventricular Delays on Gas Exchange during Excercise Chul-Ho Kim, Yong-Mei Cha, Lyle J. Olson, Kathy A. O’Malley, Dean MacCarter, Bruce D. Johnson; Cardiovascular Diseases, Mayo Clinic, Rochester, MN Background: Cardiac resynchronization therapy (CRT) has been an important treatment for patients with HF. However, 25-30% of CRT recipients do not demonstrate improvements of heart failure symptoms and/or left ventricular function after CRT. Whether altering AV and VV timing intervals would improve CRT outcomes has been controversial. The lungs are intimately linked with cardiac function. They lie hemodynamically in series with the heart and are influenced by acute changes in left heart pressure. In addition, changes in respiratory patterns and gas exchange are dynamic and may thus be influenced by timing delays. Light exercise enhances these heart and lung interactions. Purpose: The purpose of this study was to investigate changes in non-invasive gas exchange measures by optimizing AV and VV timing intervals during low intensity exercise. Methods: This prospective study included 12 males (6869 yr) and 3 females (7065 yr) who reported to the laboratory one month after CRT implantation and performed 2 walking tests on a treadmill. The protocol evaluated AV delay settings first, followed by VV delays while gas exchange was assessed. Following a 5 min warm-up (2min rest + 3min dynamic phase), there were five, 2 min intervals during which the AV delay values were programmed to 5 discrete settings 20 msec apart using an increasing AV interval sequence of 100, 120, 140, 160 & 180 msec. Then, the same procedure with 3 discrete settings (0, -20 and -40msec) was repeated for VV delays. Results: Prior to implantation, mean NYHA52.860.5, LVEF52767 and QOL 545630. As a group there was no consistent pattern of change (increase or decrease) in key gas exchange variables (e.g., O2 pulse, PetCO2, VE/VCO2) across AV and VV timing intervals (pO0.05). However, there were modest changes in these variables on an individual basis with variations in VE/VCO2 averaging 14%, O2 pulse 12% and PetCO2 10% across AV timing intervals. For VV timing intervals, variations in VE/VCO2, O2 pulse and PetCO2 were smaller and averaged 4%, 7% and 3%, respectively. However, the AV and VV timing interval that resulted in the most improved gas exchange differed from nominal settings in 12 of 15 subjects. Conclusion: These results suggest that on an individual subject basis, gas exchange measures can be improved by optimization of AV and VV timing delay and thus this technique could be used to individualize the approach to CRT optimization.
178 Can Anodal Pacing Be Utilized To Reduce Energy Requirements during Cardiac Resynchronization Therapy? Imran Niazi1, Kyungmoo Ryu2, Rebecca Dahme2, Indrajit Choudhuri1, Arshad Jahangir1, Masood Akhtar1, Jasbir Sra1; 1Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke’s Medical Centers, University of Wisconsin School of Medicine and Public Health, Milwaukee, WI; 2St. Jude Medical Inc., St. Paul, MN Introduction: Studies show that inadvertent anodal pacing occurs commonly in left ventricular (LV) leads without apparent ill effects. Hypothesis: Deliberate anodal pacing could be employed to allow multisite LV stimulation or reduce current drain if adequate right ventricular anodal thresholds can be obtained. We assessed the anodal thresholds of LV and right ventricular (RV) electrodes during cardiac resynchronization therapy (CRT) implant and compared them to cathodal thresholds at the same electrodes. Methods: Cathodal and anodal thresholds were measured in both RV and LV in 71 sequential patients undergoing CRT implant who had standard indications for CRT implant (QRS duration O120 ms, left ventricular ejection fraction !35%, New York Heart Association Class II-IV heart failure). Thresholds were measured three times using a consistent decremental method at 0.5-ms pacing pulse width, and the results averaged. The tip electrode was assessed for RV lead; all electrodes with capture were assessed for bipolar LV leads. Only equipolar LV transvenous leads from various manufacturers were included in analysis. Results: A clinically acceptable anodal threshold (!3 V at 0.5 ms pulse width) could be obtained at the RV tip lead electrode in all patients and at LV lead electrodes in at least one pacing configuration in 33 of 57 patients (58%). On average, the anodal threshold was 0.1 6 0.7 V greater than the cathodal threshold in RV lead electrode (p50.30) and 1.5 6 1.8 V greater than the cathodal threshold in LV lead electrodes (p5!0.001). There was a modest correlation between anodal and cathodal thresholds (R50.59). Conclusion: An adequate anodal threshold can be obtained in 58% of bipolar LV leads, and 100% of RV leads. Anodal pacing for multisite stimulation and energy reduction should be explored. Anodal and Cathodal Thresholds By Pacing Site Lead/ Cathodal Cathodal Anodal Anodal Electrode threshold (volts) impedance (ohms) threshold (volts) impedance (ohms)
177 Are Unipolar Pacing Thresholds Lower Than Bipolar Pacing Thresholds in Multipolar Left Ventricular Leads? Imran Niazi1, Gery Tomassoni2, James Baker3, Raffaele Corbisiero4, Charles Love5, David Martin6, Robert Sheppard7, Seth Worley8, Nicole Harbert9; 1Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke’s Medical Centers, University of Wisconsin School of Medicine and Public Health, Milwaukee, WI; 2 Lexington Cardiology Consultants, Lexington, KY; 3St. Thomas Hospital, Nashville, TN; 4Deborah Heart and Lung Center, Browns Mills, NJ; 5The Ohio State University Medical Center, Columbus, OH; 6Lahey Clinic Medical Center, Burlington, MA; 7The Heart and Vascular Institute of Florida, St. Petersburg, FL; 8 Lancaster Heart Foundation, Lancaster, PA; 9St. Jude Medical Center, Sylmar, CA Introduction: The novel QuartetÔ quadripolar lead/PromoteÔ Q CRT-D system (St. Jude Medical, Sylmar, CA, USA) offers 4 unipolar and 6 bipolar left ventricular pacing vectors. We compared unipolar to bipolar pacing thresholds at each electrode. Methods: In a prospective multicenter study, pacing thresholds for each of the 10 vectors were measured at predischarge (PD) evaluation and again at 3 months. Thresholds were determined using a consistent decremental protocol at 0.5-ms pulse width. Student’s t-test was used to compare unipolar and bipolar pacing vectors. Results: 170 patients (68.8% male, 57.6% with ischemic cardiomyopathy, mean left ventricular ejection fraction of 25 6 7%) were included in the study. The quadripolar lead was placed in a lateral or posterolateral vein in 84% of cases, and anterior, posterior or middle cardiac vein in 16% of cases. Table 1 summarizes capture thresholds for the 10 vectors and compares the bipolar and unipolar capture thresholds measured at PD and 3-month follow-up. Conclusion: For the distal 3 left ventricular lead electrodes, unipolar pacing thresholds were significantly lower than bipolar pacing thresholds. Both unipolar and bipolar capture thresholds were acceptable and remained stable over 3 months follow-up.
RV tip LV tip LV other
1.0 6 0.6 1.7 6 1.7 1.6 6 1.2
770 6 400 693 6 247 522 6 187
1.2 6 0.7 2.7 6 2.2 2.9 6 1.9
724 6 328 665 6 242 524 6 149
LV 5 left ventricle; RV 5 right ventricle
179 Accumulative Premature Ventricular Contractions Can Be a Predictor of Heart Failure Hospitalization Omid Souresrafil1, Parviz Souresrafil2; 1SCH Cardiac Hospital/University of Sydney, Maple Grove, MN; 2Cardiology, SCH Cardiac Hospital, Sydney, Australia Background: Congestive Heart Failure (CHF) patients often exhibit episodes of arrhythmias including Atrial Fibrillaiton (AF) and Ventricular Tachycardias (VT) including Premature Ventricular Contractions (PVCs). In this study an attempt was made to correlate accumulative PVC burden in patients with Class III-IV HF. Methods: 393 patients with class III-IV HF implanted with an IPG were included in this study. Subjects were consented at routine device follow ups. Cumulative amount of progressive PVC burden were collected over a 12 month period. All patients were monitored for a Heart Failure Hospitalization (HFH) event. At the HFH visit the PVC burden was collected from the IPG. At the end of 12 months the amount of cumulative PVC burden was cross correlated with HFH visits. Results: Of the 393 patients, 141614 had a cumulative average PVC burden of 25% or more. The rest had an average less than 25%. Of the 141614 patients, 8369 (58%) were hospitalized for a HF event. 6367 (25%) from the low PVC group were also Hospitalized for HF events. Conclusions: Accumulative PVC burden can be indicator of a future Heart Failure Hospitalization event.
HFSA
S55
CRT, the improvement of LVEF, LVESD, PASP and mitral regurgitation were comparable in 3 groups (PO.05). The survival estimate was the best in class I-II group and the worst in class IV group (P!.001, figure). Univariate and multivariate analysis showed that left bundle branch block (HR 0.73, CI 0.58-0.93, P5.012), age per 10 years (HR 1.43, CI 1.25-1.64, P!.001), ischemic cardiomyopathy (HR 1.70, CI 1.29-2.23, P!.001) and NYHA class IV (HR 2.48, CI 1.35-4.55, P5.003) were independent predictors for mortality. Conclusions: Patients with mild to moderate HF symptoms achieve comparable benefit from CRT in improving LV systolic function and reverse remodeling as in severe HF groups. However, NYHA functional class remains an independent predictor for all-cause mortality.
176 The Effect of Atrial-Ventricular and Interventricular Delays on Gas Exchange during Excercise Chul-Ho Kim, Yong-Mei Cha, Lyle J. Olson, Kathy A. O’Malley, Dean MacCarter, Bruce D. Johnson; Cardiovascular Diseases, Mayo Clinic, Rochester, MN Background: Cardiac resynchronization therapy (CRT) has been an important treatment for patients with HF. However, 25-30% of CRT recipients do not demonstrate improvements of heart failure symptoms and/or left ventricular function after CRT. Whether altering AV and VV timing intervals would improve CRT outcomes has been controversial. The lungs are intimately linked with cardiac function. They lie hemodynamically in series with the heart and are influenced by acute changes in left heart pressure. In addition, changes in respiratory patterns and gas exchange are dynamic and may thus be influenced by timing delays. Light exercise enhances these heart and lung interactions. Purpose: The purpose of this study was to investigate changes in non-invasive gas exchange measures by optimizing AV and VV timing intervals during low intensity exercise. Methods: This prospective study included 12 males (6869 yr) and 3 females (7065 yr) who reported to the laboratory one month after CRT implantation and performed 2 walking tests on a treadmill. The protocol evaluated AV delay settings first, followed by VV delays while gas exchange was assessed. Following a 5 min warm-up (2min rest + 3min dynamic phase), there were five, 2 min intervals during which the AV delay values were programmed to 5 discrete settings 20 msec apart using an increasing AV interval sequence of 100, 120, 140, 160 & 180 msec. Then, the same procedure with 3 discrete settings (0, -20 and -40msec) was repeated for VV delays. Results: Prior to implantation, mean NYHA52.860.5, LVEF52767 and QOL 545630. As a group there was no consistent pattern of change (increase or decrease) in key gas exchange variables (e.g., O2 pulse, PetCO2, VE/VCO2) across AV and VV timing intervals (pO0.05). However, there were modest changes in these variables on an individual basis with variations in VE/VCO2 averaging 14%, O2 pulse 12% and PetCO2 10% across AV timing intervals. For VV timing intervals, variations in VE/VCO2, O2 pulse and PetCO2 were smaller and averaged 4%, 7% and 3%, respectively. However, the AV and VV timing interval that resulted in the most improved gas exchange differed from nominal settings in 12 of 15 subjects. Conclusion: These results suggest that on an individual subject basis, gas exchange measures can be improved by optimization of AV and VV timing delay and thus this technique could be used to individualize the approach to CRT optimization.
178 Can Anodal Pacing Be Utilized To Reduce Energy Requirements during Cardiac Resynchronization Therapy? Imran Niazi1, Kyungmoo Ryu2, Rebecca Dahme2, Indrajit Choudhuri1, Arshad Jahangir1, Masood Akhtar1, Jasbir Sra1; 1Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke’s Medical Centers, University of Wisconsin School of Medicine and Public Health, Milwaukee, WI; 2St. Jude Medical Inc., St. Paul, MN Introduction: Studies show that inadvertent anodal pacing occurs commonly in left ventricular (LV) leads without apparent ill effects. Hypothesis: Deliberate anodal pacing could be employed to allow multisite LV stimulation or reduce current drain if adequate right ventricular anodal thresholds can be obtained. We assessed the anodal thresholds of LV and right ventricular (RV) electrodes during cardiac resynchronization therapy (CRT) implant and compared them to cathodal thresholds at the same electrodes. Methods: Cathodal and anodal thresholds were measured in both RV and LV in 71 sequential patients undergoing CRT implant who had standard indications for CRT implant (QRS duration O120 ms, left ventricular ejection fraction !35%, New York Heart Association Class II-IV heart failure). Thresholds were measured three times using a consistent decremental method at 0.5-ms pacing pulse width, and the results averaged. The tip electrode was assessed for RV lead; all electrodes with capture were assessed for bipolar LV leads. Only equipolar LV transvenous leads from various manufacturers were included in analysis. Results: A clinically acceptable anodal threshold (!3 V at 0.5 ms pulse width) could be obtained at the RV tip lead electrode in all patients and at LV lead electrodes in at least one pacing configuration in 33 of 57 patients (58%). On average, the anodal threshold was 0.1 6 0.7 V greater than the cathodal threshold in RV lead electrode (p50.30) and 1.5 6 1.8 V greater than the cathodal threshold in LV lead electrodes (p5!0.001). There was a modest correlation between anodal and cathodal thresholds (R50.59). Conclusion: An adequate anodal threshold can be obtained in 58% of bipolar LV leads, and 100% of RV leads. Anodal pacing for multisite stimulation and energy reduction should be explored. Anodal and Cathodal Thresholds By Pacing Site Lead/ Cathodal Cathodal Anodal Anodal Electrode threshold (volts) impedance (ohms) threshold (volts) impedance (ohms)
177 Are Unipolar Pacing Thresholds Lower Than Bipolar Pacing Thresholds in Multipolar Left Ventricular Leads? Imran Niazi1, Gery Tomassoni2, James Baker3, Raffaele Corbisiero4, Charles Love5, David Martin6, Robert Sheppard7, Seth Worley8, Nicole Harbert9; 1Aurora Cardiovascular Services, Aurora Sinai/Aurora St. Luke’s Medical Centers, University of Wisconsin School of Medicine and Public Health, Milwaukee, WI; 2 Lexington Cardiology Consultants, Lexington, KY; 3St. Thomas Hospital, Nashville, TN; 4Deborah Heart and Lung Center, Browns Mills, NJ; 5The Ohio State University Medical Center, Columbus, OH; 6Lahey Clinic Medical Center, Burlington, MA; 7The Heart and Vascular Institute of Florida, St. Petersburg, FL; 8 Lancaster Heart Foundation, Lancaster, PA; 9St. Jude Medical Center, Sylmar, CA Introduction: The novel QuartetÔ quadripolar lead/PromoteÔ Q CRT-D system (St. Jude Medical, Sylmar, CA, USA) offers 4 unipolar and 6 bipolar left ventricular pacing vectors. We compared unipolar to bipolar pacing thresholds at each electrode. Methods: In a prospective multicenter study, pacing thresholds for each of the 10 vectors were measured at predischarge (PD) evaluation and again at 3 months. Thresholds were determined using a consistent decremental protocol at 0.5-ms pulse width. Student’s t-test was used to compare unipolar and bipolar pacing vectors. Results: 170 patients (68.8% male, 57.6% with ischemic cardiomyopathy, mean left ventricular ejection fraction of 25 6 7%) were included in the study. The quadripolar lead was placed in a lateral or posterolateral vein in 84% of cases, and anterior, posterior or middle cardiac vein in 16% of cases. Table 1 summarizes capture thresholds for the 10 vectors and compares the bipolar and unipolar capture thresholds measured at PD and 3-month follow-up. Conclusion: For the distal 3 left ventricular lead electrodes, unipolar pacing thresholds were significantly lower than bipolar pacing thresholds. Both unipolar and bipolar capture thresholds were acceptable and remained stable over 3 months follow-up.
RV tip LV tip LV other
1.0 6 0.6 1.7 6 1.7 1.6 6 1.2
770 6 400 693 6 247 522 6 187
1.2 6 0.7 2.7 6 2.2 2.9 6 1.9
724 6 328 665 6 242 524 6 149
LV 5 left ventricle; RV 5 right ventricle
179 Accumulative Premature Ventricular Contractions Can Be a Predictor of Heart Failure Hospitalization Omid Souresrafil1, Parviz Souresrafil2; 1SCH Cardiac Hospital/University of Sydney, Maple Grove, MN; 2Cardiology, SCH Cardiac Hospital, Sydney, Australia Background: Congestive Heart Failure (CHF) patients often exhibit episodes of arrhythmias including Atrial Fibrillaiton (AF) and Ventricular Tachycardias (VT) including Premature Ventricular Contractions (PVCs). In this study an attempt was made to correlate accumulative PVC burden in patients with Class III-IV HF. Methods: 393 patients with class III-IV HF implanted with an IPG were included in this study. Subjects were consented at routine device follow ups. Cumulative amount of progressive PVC burden were collected over a 12 month period. All patients were monitored for a Heart Failure Hospitalization (HFH) event. At the HFH visit the PVC burden was collected from the IPG. At the end of 12 months the amount of cumulative PVC burden was cross correlated with HFH visits. Results: Of the 393 patients, 141614 had a cumulative average PVC burden of 25% or more. The rest had an average less than 25%. Of the 141614 patients, 8369 (58%) were hospitalized for a HF event. 6367 (25%) from the low PVC group were also Hospitalized for HF events. Conclusions: Accumulative PVC burden can be indicator of a future Heart Failure Hospitalization event.