- Email: [email protected]
P6-91
Poster 6 Methods: We followed 52 pts with an InSync Sentry™ (88% male, age 67⫾1 years, 60% ICM, 40% DCM) for 12⫾1 weeks. OptiVol™ Alert was ‘on‘ with a programmable threshold of 60 (nominal value). Devices were interrogated, CHF status evaluated and NT-proBNP measured if pts presented for routine follow-up, with cardiac decompensation and /or an OptiVol™ Alert. CHF was classified into ‘stable‘ or ‘decompensated‘ utilizing a scoring system based on changes in NYHA class, physical examination, 6 min. walk test, NT-proBNP and chest-⫻-ray. Results: To date there were 34 alert events in 17 pts. Eight events were excluded from analysis because CHF status could not be evaluated in time (e.g. alarm not heard). Seven pts presented with CHF decompensation without concomitant alert. Overall, the OptiVol™ Alert detected CHF decompensation with 68% sensitivity (17/25) and a positive predictive value of 65% (17/26). At baseline, average intrathoracic impedance was 66⫾2 and NT-proBNP 2976⫾758 ng/l. During follow-up, a significant correlation was present between individual changes in impedance and NT-proBNP (r⫽-0.49, p⬍0.001). Conclusions: 1) Individual changes in intrathoracic impedance, as measured by an implanted device, correlate with NT-proBNP. 2) An audible alert, triggered by a decrease in impedance, facilitates the detection of CHF decompensation. 3) Using nominal device programming, the OptiVol™ Alert does not detect CHF decompensation in 1/3 of the cases, while deterioration of CHF can not be verified in 35% of the alert events.
P6-89 ESTIMATED VERSUS DIRECT MEASURED MET LEVELS IN ASSESSING CHRONOTROPIC RESPONSE: IS IT SUFFICIENT? Roger A. Freedman, MD, John F. Macgregor, MD, Lizbeth M. Mino, PhD, Kira Q. Stolen, PhD, Donald Hopper, PhD, Stacia Merkel, BS, Timothy E. Meyer, PhD, Kenneth Beck, PhD and James A. Coman, MD. University of Utah Medical Center, Salt Lake City, UT, Guidant Corporation, Salt Lake City, UT, Guidant Corporation, St. Paul, MN and Oklahoma Heart Institute, Tulsa, OK. Background: Inadequate heart rate response to exercise, or chronotropic incompetence, can be clinically assessed and defined using several methods. The most rigorous method uses analysis of cardiopulmonary gas exchange (CPX), which allows direct measurement of metabolic (MET) level during exercise and yields an absolute measurement of metabolic chronotropic relation (MCR). A less rigorous method, devised by Wilkoff, yields estimated MCR using treadmill speed and grade. The current analysis compares these two methods of estimating the MCR slope. Methods: Seventy-six patients enrolled in the Limiting Chronotropic Incompetence for Pacemaker Recipients (LIFE) Study, a study of chronotropic responsiveness, underwent CPX testing for the purpose of comparing estimated MET levels to directly measured MET levels. All patients were indicated for dual chamber pacemaker and completed a Chronotropic Assessment Exercise Protocol (CAEP) treadmill test with CPX measurements 30 days post pacemaker implant. Pacemakers were programmed to a lower pacing rate of 60 ppm with rate responsive pacing turned off. All patients achieved a perceived exertion rating ⱖ16 on the Borg scale and had a respiratory exchange ratio between 0.9 - 1.3. MCR slope was calculated using direct oxygen uptake measurements with CPX (SLOPECPX) and using Wilkoff method (SLOPEEST). Results: A significant positive correlation was found between SLOPEEST and SLOPECPX (r⫽ 0.96; p⬍0.0001). On average, SLOPEEST was significantly (p⬍0.001) but only slightly greater than SLOPECPX (median difference -0.03). Conclusion: The above data demonstrate that calculating the MCR slope using estimated MET levels from treadmill speed and grade is adequate for assessing chronotropic response in the vast majority of patients in a bradycardia population.
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P6-90 EFFECT OF VENTRICULAR PACING ON CARDIAC APEX ROTATION ASSESSED BY AN IMPLANTED CORIOLIS FORCE SENSOR Emanuela Marcelli, PhD, Gianni Plicchi, PhD, Laura Cercenelli, PhD and Mario Parlapiano, MD. Bologna University, Bologna, Italy. Background: Cardiac Apex Rotation (CAR) has been shown to provide a sensitive index of both systolic and diastolic Left Ventricle (LV) dynamics. As an alternative to sophisticated techniques (i.e. radiopacque markers and tagged magnetic resonance) not suitable for a chronic monitoring of LV dynamics we recently proposed the use of an implanted gyroscopic sensor (Gyro) based on Coriolis force to quantify CAR. The purpose of this study was to evaluate in a sheep model the effects of asynchronous contraction and relaxation resulting from ventricular pacing on the rotational mechanics of LV over the full cycle. Materials and Methods: The sheep heart was initially paced from right atrium (RA) and subsequently from apex of right ventricle (RVa), pacing simultaneously the RA to override the intrinsic sinoatrial node excitation. To assess CAR, left-sided thoracotomy was performed and a small Gyro (CG-L53, Nec-Tokin, 16x8x5mm) was epicardially glued on the cardiac apex; LV pressure (LVP) was assessed using a Millar pressure catheter. Angle of CAR () was obtained by integration of apex twist rate () measured by the Gyro. Variations of maximum systolic twist rate (max_s) and maximum diastolic untwist rate (max_d) were compared to variations of the hemodynamic parameters of systolic (LVdP/dtmax) and diastolic (LVdP/dtmin) cardiac function derived by LVP. Results: From RA to RVa pacing an increase of max_s (⫹7.9⫾0.7%) and a marked decrease of max_d (-20.0⫾0.6%) resulted, while minimally changed (-2.6⫾14.1%). Conversely, LVdP/dt showed slight variations (-2.9⫾5.2% for LVdP/dtmax, ⫹5.0⫾2.5%, for LVdP/dtmin). Conclusions: Results suggest that the asynchronous contraction resulting from RVa pacing alters the normal physiological LV twist patterns, particularly affecting the maximum diastolic untwist rate (max_d) assessed by an epicardial gyroscopic sensor.
P6-91 ENDOCARDIAL TEMPERATURE SENSORS TO LOCATE THE CORONARY SINUS FOR CARDIAC RESYNCHRONISATION THERAPY -A NOVEL APPROACH David J. Fox, MRCP, Rogier Receveur, BSc, Vincent Larik, BSc, Sanjiv Petkar, MRCP, Neil C. Davidson, MD, FRCP and Adam P. Fitzpatrick, MD, FRCP. Manchester Heart Centre, Manchester, United Kingdom, Bakken Research Center, Maastricht, The Netherlands and North West
S332 Regional Cardiac Centre, Wythenshawe Hospital, Manchester, United Kingdom. Introduction: Cannulation of the coronary sinus (CS) for cardiac resynchronisation therapy (CRT) can be time consuming. A high contrast load may be needed to identify the CS and pre-existing renal dysfunction may be exacerbated by contrast induced nephropathy. Hypothesis: We hypothesised that sensitive temperature sensors (TS) could assist in identifying the CS. Previous studies have identified venous blood exiting the CS as being approximately 0.15oC warmer than right atrial blood due to the intense metabolic activity of the heart. Methods: 4 male patients receiving CRT were recruited. We developed a sensitive (0.01oC) and responsive (80msec) endocardial temperature measurement device (TS) that can accurately display real time temperatures from within the heart. The TS had an audible tone, the pitch of which increased at higher temperatures. The device had a TS on a pacing electrode which was deployed down the CS guide catheter. The TS was deployed under X-ray control, 2mm outside the guide catheter ostium for cannulating the CS. Multiple cannulations of the CS were performed per patient, with a delay of 1 minute between each cannulation. Results: All patients had a rise in both temperature and audible tone on entering the ostium of the CS. An average of 7.5 measurements were taken per patient (range n⫽1-10). Results are the mean increase in temperature (in o C): Patient (P) 1 mean 0.19 SEM n/a, P2 mean 0.1 SEM 0.06, P3 mean 0.1 SEM 0.02, P4 mean 0.1 SEM 0.03. The ability to enter the CS without the use of contrast was seen in all patients, with subsequent confirmation of CS location with contrast. Mean CS blood temperature was significantly warmer than right atrial blood (p⬍0.0001). The rise in temperature was seen at the CS ostium. Mean increase of all the measurements was 0.12 oC, SD 0.04. Conclusions: A TS deployed as an adjunct to a guide catheter may reduce the amount of contrast required and speed up cannulation of the CS. A reduction of contrast usage may also reduce the incidence of contrast induced nephropathy. This is the first reported use of a TS as an adjunct to left heart lead placement in CRT. P6-92 SCAR BURDEN PREDICTS LEFT VENTRICULAR RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY Daniel H. Cooper, MD, Alan D. Waggoner, MS, Victor G. Davila-Roman, MD, Marye J. Gleva, MD and Mitchell N. Faddis, MD, PhD. Washington University School of Medicine, St. Louis, MO. Background: Cardiac Resynchronization Therapy (CRT) improves dyssynchronous ventricular contraction. However, up to 30% of patients fail to respond despite meeting accepted implant criteria. A potential mechanism of non-response to CRT is the presence of a large burden of myocardial scar that contributes to dyssynchrony but does not respond to CRT. Objective: The purpose of this study was to examine the relationship between CRT response and myocardial scar burden determined by preoperative nuclear stress imaging. Methods: Twenty-one patients with LV dysfunction (LVEF⬍35%), NYHA class III-IV, and QRS⬎130 ms received biventricular devices. LV end systolic volume (LVESV), LV ejection fraction (LVEF), and NYHA class were measured pre-CRT and at 3 months post-CRT. Myocardial viability was determined by review of stress thallium results obtained prior to CRT. Resting perfusion defects indicative of infarct were assessed in all myocardial segments and classified as small, moderate, or large and then summed to give an objective measure of scar burden. Results: 21 patients were classified as responders (R) or non-responders (NR) based on a ⱖ 10% decrease in LVESV obtained at their 3 month follow-up echocardiogram. There was no difference in clinical response observed between groups with 12 out of 14 in the R group and 5 out of 7 in the NR group demonstrating an improvement in NYHA class. The R group had a mean scar burden score of 3.9 ⫾ 3.2% vs. 7.6 ⫾ 3.6 in the NR group (p⫽0.03). A linear regression applied to the data set revealed a significant (p ⫽ 0.04, r ⫽ -0.44) inverse relationship between LVESV (%
Heart Rhythm, Vol 3, No 5, May Supplement 2006 decrease) and scar burden (See Fig. 1). The R group had a mean LVEF increase of 8.4% ⫾ 5.7% vs. 3.5% ⫾ 3.4% in the NR group (p⫽0.058). Conclusions: Myocardial scar burden, as determined by nuclear imaging, is a significant predictor of the degree of LV remodeling observed with CRT.
P6-93 DO ATRIAL AND VENTRICULAR SEPTAL LEAD POSITIONS RESULT IN A SHORTER SENSED AV DELAY? Mårten Rosenqvist, MD, PhD, Fikru Maru, MD and Fredrik Gadler, MD. South Hospital, Stockholm, Sweden, Danderyd Hospital, Stockholm, Sweden and Karolinska Institute, Stockholm, Sweden. Background: Ventricular apical pacing might cause atrial fibrillation and a dilatation of the left ventricle with a risk for development of congestive heart failure. Ventricular pacing should thus be avoided in patients with spontaneous heart activity. We hypothesized that the sensed atrioventricular (AV) interval could be decreased by placing the pacemaker leads in the inferior atrial septum (IAS) and at the right ventricular septum (RVS), thereby facilitating spontaneous conduction. Methods: 18 patients with the tachycardia-bradycardia syndrome being candidates for permanent pacing received a DDDR pacemaker. The atrial (A) lead was placed in the IAS and the V lead in the RV septum. In a control group of 17 patients with similar clinical characteristics the electrodes were located in the right atrial appendage and the RV apex. Spontaneously sensed AV and PQ intervals were measured in a blinded fashion. Results: The sensed AV interval was significantly shorter in the experimental group compared with the control group (167 ms vs. 209 ms p⫽0.004 (95% CI -69 to -14 ms). There were no difference in the spontaneous PQ interval between the two groups . Conclusion: By optimizing the electrode position in the atrium and the ventricle a shorter sensed AV interval is achieved. This should facilitate preservation of conducted spontaneous heart rhythm in the presence of a DDDR pacemaker. P6-94 HEMODYNAMIC EFFECTS OF COUPLED PACING WITH HIGHFREQUENCY PULSE TRAINS IN THE PORCINE HEART Vincent Splett, MS and David Euler, PhD. Medtronic, Minneapolis, MN. Background: Post-extrasystolic potentiation (PESP) is a well-established property of cardiac muscle whereby premature stimulation of ventricle increases contractility of successive beats. Delivery of an extrastimulus after every intrinsic ventricular depolarization (coupled pacing) results in sustained PESP. Since previous studies of coupled pacing used single extrastimuli, this study investigated the hemodynamic effect of coupled pacing with high-frequency pulse trains. Methods: Experiments were performed in 6 close-chest anesthetized pigs with normal cardiac function. Left ventricular and aortic pressure was
P6-89 ESTIMATED VERSUS DIRECT MEASURED MET LEVELS IN ASSESSING CHRONOTROPIC RESPONSE: IS IT SUFFICIENT? Roger A. Freedman, MD, John F. Macgregor, MD, Lizbeth M. Mino, PhD, Kira Q. Stolen, PhD, Donald Hopper, PhD, Stacia Merkel, BS, Timothy E. Meyer, PhD, Kenneth Beck, PhD and James A. Coman, MD. University of Utah Medical Center, Salt Lake City, UT, Guidant Corporation, Salt Lake City, UT, Guidant Corporation, St. Paul, MN and Oklahoma Heart Institute, Tulsa, OK. Background: Inadequate heart rate response to exercise, or chronotropic incompetence, can be clinically assessed and defined using several methods. The most rigorous method uses analysis of cardiopulmonary gas exchange (CPX), which allows direct measurement of metabolic (MET) level during exercise and yields an absolute measurement of metabolic chronotropic relation (MCR). A less rigorous method, devised by Wilkoff, yields estimated MCR using treadmill speed and grade. The current analysis compares these two methods of estimating the MCR slope. Methods: Seventy-six patients enrolled in the Limiting Chronotropic Incompetence for Pacemaker Recipients (LIFE) Study, a study of chronotropic responsiveness, underwent CPX testing for the purpose of comparing estimated MET levels to directly measured MET levels. All patients were indicated for dual chamber pacemaker and completed a Chronotropic Assessment Exercise Protocol (CAEP) treadmill test with CPX measurements 30 days post pacemaker implant. Pacemakers were programmed to a lower pacing rate of 60 ppm with rate responsive pacing turned off. All patients achieved a perceived exertion rating ⱖ16 on the Borg scale and had a respiratory exchange ratio between 0.9 - 1.3. MCR slope was calculated using direct oxygen uptake measurements with CPX (SLOPECPX) and using Wilkoff method (SLOPEEST). Results: A significant positive correlation was found between SLOPEEST and SLOPECPX (r⫽ 0.96; p⬍0.0001). On average, SLOPEEST was significantly (p⬍0.001) but only slightly greater than SLOPECPX (median difference -0.03). Conclusion: The above data demonstrate that calculating the MCR slope using estimated MET levels from treadmill speed and grade is adequate for assessing chronotropic response in the vast majority of patients in a bradycardia population.
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P6-90 EFFECT OF VENTRICULAR PACING ON CARDIAC APEX ROTATION ASSESSED BY AN IMPLANTED CORIOLIS FORCE SENSOR Emanuela Marcelli, PhD, Gianni Plicchi, PhD, Laura Cercenelli, PhD and Mario Parlapiano, MD. Bologna University, Bologna, Italy. Background: Cardiac Apex Rotation (CAR) has been shown to provide a sensitive index of both systolic and diastolic Left Ventricle (LV) dynamics. As an alternative to sophisticated techniques (i.e. radiopacque markers and tagged magnetic resonance) not suitable for a chronic monitoring of LV dynamics we recently proposed the use of an implanted gyroscopic sensor (Gyro) based on Coriolis force to quantify CAR. The purpose of this study was to evaluate in a sheep model the effects of asynchronous contraction and relaxation resulting from ventricular pacing on the rotational mechanics of LV over the full cycle. Materials and Methods: The sheep heart was initially paced from right atrium (RA) and subsequently from apex of right ventricle (RVa), pacing simultaneously the RA to override the intrinsic sinoatrial node excitation. To assess CAR, left-sided thoracotomy was performed and a small Gyro (CG-L53, Nec-Tokin, 16x8x5mm) was epicardially glued on the cardiac apex; LV pressure (LVP) was assessed using a Millar pressure catheter. Angle of CAR () was obtained by integration of apex twist rate () measured by the Gyro. Variations of maximum systolic twist rate (max_s) and maximum diastolic untwist rate (max_d) were compared to variations of the hemodynamic parameters of systolic (LVdP/dtmax) and diastolic (LVdP/dtmin) cardiac function derived by LVP. Results: From RA to RVa pacing an increase of max_s (⫹7.9⫾0.7%) and a marked decrease of max_d (-20.0⫾0.6%) resulted, while minimally changed (-2.6⫾14.1%). Conversely, LVdP/dt showed slight variations (-2.9⫾5.2% for LVdP/dtmax, ⫹5.0⫾2.5%, for LVdP/dtmin). Conclusions: Results suggest that the asynchronous contraction resulting from RVa pacing alters the normal physiological LV twist patterns, particularly affecting the maximum diastolic untwist rate (max_d) assessed by an epicardial gyroscopic sensor.
P6-91 ENDOCARDIAL TEMPERATURE SENSORS TO LOCATE THE CORONARY SINUS FOR CARDIAC RESYNCHRONISATION THERAPY -A NOVEL APPROACH David J. Fox, MRCP, Rogier Receveur, BSc, Vincent Larik, BSc, Sanjiv Petkar, MRCP, Neil C. Davidson, MD, FRCP and Adam P. Fitzpatrick, MD, FRCP. Manchester Heart Centre, Manchester, United Kingdom, Bakken Research Center, Maastricht, The Netherlands and North West
S332 Regional Cardiac Centre, Wythenshawe Hospital, Manchester, United Kingdom. Introduction: Cannulation of the coronary sinus (CS) for cardiac resynchronisation therapy (CRT) can be time consuming. A high contrast load may be needed to identify the CS and pre-existing renal dysfunction may be exacerbated by contrast induced nephropathy. Hypothesis: We hypothesised that sensitive temperature sensors (TS) could assist in identifying the CS. Previous studies have identified venous blood exiting the CS as being approximately 0.15oC warmer than right atrial blood due to the intense metabolic activity of the heart. Methods: 4 male patients receiving CRT were recruited. We developed a sensitive (0.01oC) and responsive (80msec) endocardial temperature measurement device (TS) that can accurately display real time temperatures from within the heart. The TS had an audible tone, the pitch of which increased at higher temperatures. The device had a TS on a pacing electrode which was deployed down the CS guide catheter. The TS was deployed under X-ray control, 2mm outside the guide catheter ostium for cannulating the CS. Multiple cannulations of the CS were performed per patient, with a delay of 1 minute between each cannulation. Results: All patients had a rise in both temperature and audible tone on entering the ostium of the CS. An average of 7.5 measurements were taken per patient (range n⫽1-10). Results are the mean increase in temperature (in o C): Patient (P) 1 mean 0.19 SEM n/a, P2 mean 0.1 SEM 0.06, P3 mean 0.1 SEM 0.02, P4 mean 0.1 SEM 0.03. The ability to enter the CS without the use of contrast was seen in all patients, with subsequent confirmation of CS location with contrast. Mean CS blood temperature was significantly warmer than right atrial blood (p⬍0.0001). The rise in temperature was seen at the CS ostium. Mean increase of all the measurements was 0.12 oC, SD 0.04. Conclusions: A TS deployed as an adjunct to a guide catheter may reduce the amount of contrast required and speed up cannulation of the CS. A reduction of contrast usage may also reduce the incidence of contrast induced nephropathy. This is the first reported use of a TS as an adjunct to left heart lead placement in CRT. P6-92 SCAR BURDEN PREDICTS LEFT VENTRICULAR RESPONSE TO CARDIAC RESYNCHRONIZATION THERAPY Daniel H. Cooper, MD, Alan D. Waggoner, MS, Victor G. Davila-Roman, MD, Marye J. Gleva, MD and Mitchell N. Faddis, MD, PhD. Washington University School of Medicine, St. Louis, MO. Background: Cardiac Resynchronization Therapy (CRT) improves dyssynchronous ventricular contraction. However, up to 30% of patients fail to respond despite meeting accepted implant criteria. A potential mechanism of non-response to CRT is the presence of a large burden of myocardial scar that contributes to dyssynchrony but does not respond to CRT. Objective: The purpose of this study was to examine the relationship between CRT response and myocardial scar burden determined by preoperative nuclear stress imaging. Methods: Twenty-one patients with LV dysfunction (LVEF⬍35%), NYHA class III-IV, and QRS⬎130 ms received biventricular devices. LV end systolic volume (LVESV), LV ejection fraction (LVEF), and NYHA class were measured pre-CRT and at 3 months post-CRT. Myocardial viability was determined by review of stress thallium results obtained prior to CRT. Resting perfusion defects indicative of infarct were assessed in all myocardial segments and classified as small, moderate, or large and then summed to give an objective measure of scar burden. Results: 21 patients were classified as responders (R) or non-responders (NR) based on a ⱖ 10% decrease in LVESV obtained at their 3 month follow-up echocardiogram. There was no difference in clinical response observed between groups with 12 out of 14 in the R group and 5 out of 7 in the NR group demonstrating an improvement in NYHA class. The R group had a mean scar burden score of 3.9 ⫾ 3.2% vs. 7.6 ⫾ 3.6 in the NR group (p⫽0.03). A linear regression applied to the data set revealed a significant (p ⫽ 0.04, r ⫽ -0.44) inverse relationship between LVESV (%
Heart Rhythm, Vol 3, No 5, May Supplement 2006 decrease) and scar burden (See Fig. 1). The R group had a mean LVEF increase of 8.4% ⫾ 5.7% vs. 3.5% ⫾ 3.4% in the NR group (p⫽0.058). Conclusions: Myocardial scar burden, as determined by nuclear imaging, is a significant predictor of the degree of LV remodeling observed with CRT.
P6-93 DO ATRIAL AND VENTRICULAR SEPTAL LEAD POSITIONS RESULT IN A SHORTER SENSED AV DELAY? Mårten Rosenqvist, MD, PhD, Fikru Maru, MD and Fredrik Gadler, MD. South Hospital, Stockholm, Sweden, Danderyd Hospital, Stockholm, Sweden and Karolinska Institute, Stockholm, Sweden. Background: Ventricular apical pacing might cause atrial fibrillation and a dilatation of the left ventricle with a risk for development of congestive heart failure. Ventricular pacing should thus be avoided in patients with spontaneous heart activity. We hypothesized that the sensed atrioventricular (AV) interval could be decreased by placing the pacemaker leads in the inferior atrial septum (IAS) and at the right ventricular septum (RVS), thereby facilitating spontaneous conduction. Methods: 18 patients with the tachycardia-bradycardia syndrome being candidates for permanent pacing received a DDDR pacemaker. The atrial (A) lead was placed in the IAS and the V lead in the RV septum. In a control group of 17 patients with similar clinical characteristics the electrodes were located in the right atrial appendage and the RV apex. Spontaneously sensed AV and PQ intervals were measured in a blinded fashion. Results: The sensed AV interval was significantly shorter in the experimental group compared with the control group (167 ms vs. 209 ms p⫽0.004 (95% CI -69 to -14 ms). There were no difference in the spontaneous PQ interval between the two groups . Conclusion: By optimizing the electrode position in the atrium and the ventricle a shorter sensed AV interval is achieved. This should facilitate preservation of conducted spontaneous heart rhythm in the presence of a DDDR pacemaker. P6-94 HEMODYNAMIC EFFECTS OF COUPLED PACING WITH HIGHFREQUENCY PULSE TRAINS IN THE PORCINE HEART Vincent Splett, MS and David Euler, PhD. Medtronic, Minneapolis, MN. Background: Post-extrasystolic potentiation (PESP) is a well-established property of cardiac muscle whereby premature stimulation of ventricle increases contractility of successive beats. Delivery of an extrastimulus after every intrinsic ventricular depolarization (coupled pacing) results in sustained PESP. Since previous studies of coupled pacing used single extrastimuli, this study investigated the hemodynamic effect of coupled pacing with high-frequency pulse trains. Methods: Experiments were performed in 6 close-chest anesthetized pigs with normal cardiac function. Left ventricular and aortic pressure was