BACKGROUND:In patients with heart failure and reduced left ventricular ejection fraction (LVEF), the effect of upgrading from right ventricular (RV) apical to biventricular pacing on RV and left ventricular (LV) volumes and ejection fraction (EF) is unknown. Also, the relationship of symptom improvement after biventricular upgrade to RV and LV volumes and EF has not been clarified.METHODS AND RESULTS:Nineteen patients with long-standing persistent RV apical pacing who had heart failure symptoms and echocardiographic LVEF of 0.40 or less underwent upgrade to biventricular pacing. Patients had single-photon emission computed tomographic equilibrium radionuclide angiocardiography immediately before and at 3-6 months after the upgrade procedure, to measure RV and LV volumes and EF. Biventricular upgrade was associated with increase in LVEF and decrease in LV end-diastolic and end-systolic volumes; right ventricular ejection fraction (RVEF) and end-diastolic and end-systolic volumes were unaltered. Patients with improvement in New York Heart Association heart failure class of I or more had larger initial LV end-diastolic volumes than patients without an improvement and had decreased LV end-diastolic and end-systolic volumes comparatively. Symptom improvement was not associated with RVEF and volume change.CONCLUSION:Symptom improvement with LV remodeling, but not RV remodeling, occurs 3-6 months after biventricular upgrade in patients with heart failure.

Background: A left ventricular (EF) ejection fraction (EF) of 0.35 or less is an important criterion when considering the need for cardiac resychronization therapy (CRT). Current guidelines do not distinguish between methods of LVEF measurement. This study was undertaken to determine if differences existed between echocardiographic (ECHO) and equilibrium radionuclide angiocardiographic (ERNA) estimates of LVEF and to determine if these differences could be clinically relevant when considering CRT. Patients and Methods: Twenty-six patients with heart failure and chronic right ventricular pacing scheduled for CRT were studied. All patients had LVEF of 0.35 or less by ECHO. These patients also underwent both planar and tomographic ERNA prior to CRT; tomographic ERNA had been previously successfully validated against computed tomographic angiography for LV assessment. Results: LVEF measured by ECHO was 0.27±0.06 and was similar to that measured by planar ERNA (0.26±0.08); both ECHO and planar ERNA LVEF were significantly less (p=0.01 and p=<0.0001 respectively) than that measured by tomographic ERNA (0.33±0.10). Markedly different ranges of LVEF were seen amongst the three methods: ECHO range 0.16 to 0.35, planar ERNA range 0.13 to 0.43 and tomographic ERNA range 0.15 to 0.51. Of note, 3 (12%) patients had LVEF>0.35 with planar ERNA and 10 (38%) had LVEF>0.35 with tomographic ERNA. Conclusions: There was considerable variation between LVEF measured by ECHO and planar and tomographic ERNA. Over a tenth of patients following planar and over a third following tomographic ERNA did not have LVEF of 0.35 or less. Thus the method of LVEF determination may have impact on the decision to initiate CRT and the measurement of the response to CRT. These findings suggest that the method of LVEF measurement should be considered when planning clinical trials to assess CRT.

Introduction: Cardiac resynchronization therapy (CRT) can improve left ventricular (LV) hemodynamics and function. Recent data suggest the energy cost of such improvement is favorable. The effects of sequential CRT on myocardial oxidative metabolism (MVO2) and efficiency have not been previously assessed. Methods and Results: Eight patients with NYHA class III heart failure were studied 196 ± 180 days after CRT implant. Dynamic [11C]acetate positron emission tomography (PET) and echocardiography were performed after 1 hour of: 1) AAI pacing, 2) simultaneous CRT, and 3) sequential CRT. MVO2 was calculated using the monoexponential clearance rate of [11C]acetate (kmono). Myocardial efficiency was expressed in terms of the work metabolic index (WMI). P values represent overall significance from repeated measures analysis. Global LV and right ventricular (RV) MVO2 were not significantly different between pacing modes, but the septal/lateral MVO2 ratio differed significantly with the change in pacing mode (AAI pacing = 0.696 ± 0.094 min−1, simultaneous CRT = 0.975 ± 0.143 min−1, and sequential CRT = 0.938 ± 0.189 min−1; overall P = 0.001). Stroke volume index (SVI) (AAI pacing = 26.7 ± 10.4 mL/m2, simultaneous CRT = 30.6 ± 11.2 mL/m2, sequential CRT = 33.5 ± 12.2 mL/m2; overall P < 0.001) and WMI (AAI pacing = 3.29 ± 1.34 mmHg*mL/m2*106, simultaneous CRT = 4.29 ± 1.72 mmHg*mL/m2*106, sequential CRT = 4.79 ± 1.92 mmHg*mL/m2*106; overall P = 0.002) also differed between pacing modes. Compared with simultaneous CRT, additional changes in septal/lateral MVO2, SVI, and WMI with sequential CRT were not statistically significant on post hoc analysis. Conclusion: In this small selected population, CRT increases LV SVI without increasing MVO2, resulting in improved myocardial efficiency. Additional improvements in LV work, oxidative metabolism, and efficiency from simultaneous to sequential CRT were not significant.

UNLABELLED:PET absolute myocardial blood flow (MBF) with H(2)15O and 13NH3 are widely used in clinical and research settings. However, their reproducibility with a 16-myocardial segment model has not been examined in chronic coronary artery disease (CAD). We examined the short-term reproducibility of PET H(2)15O MBF and PET 13NH3 MBF in an animal model of chronic CAD.METHODS:Twelve swine (mean weight +/- SD, 38 +/- 5 kg) underwent percutaneous placement of a copper stent in the mid circumflex coronary artery, resulting in an intense inflammatory fibrotic reaction with luminal stenosis at 4 wk. Each animal underwent repeated resting MBF measurements by PET H(2)15O and PET 13NH3. Attenuation-corrected images were analyzed using commercial software to yield absolute MBF (mL/min/g) in 16 myocardial segments. MBF was also normalized to the rate.pressure product (RPP).RESULTS:By Bland-Altman reproducibility plots, the mean difference was 0.01 +/- 0.18 mL/min/g and 0.01 +/- 0.11 mL/min/g, with confidence limits of +/-0.36 and +/-0.22 mL/min/g for uncorrected regional PET H(2)15O MBF and for uncorrected regional PET 13NH3 MBF, respectively. The repeatability coefficient ranged from 0.09 to 0.43 mL/min/g for H(2)15O and from 0.09 to 0.18 mL/min/g for 13NH3 regional MBF. RPP correction did not improve reproducibility for either PET H(2)15O or PET 13NH3 MBF. The mean difference in PET H(2)15O MBF was 0.03 +/- 0.14 mL/min/g and 0.02 +/- 0.19 mL/min/g for infarcted and remote regions, respectively, and in PET 13NH3 MBF was 0.03 +/- 0.11 mL/min/g and 0.00 +/- 0.09 mL/min/g for infarcted and remote regions, respectively.CONCLUSION:PET H(2)15O and PET 13NH3 resting MBF showed excellent reproducibility in a closed-chest animal model of chronic CAD. Resting PET 13NH3 MBF was more reproducible than resting PET H(2)15O MBF. A high level of reproducibility was maintained in areas of lower flow with infarction for both isotopes.

PET absolute myocardial blood flow (MBF) with (H2O)-O-15 and (NH3)-N-13 are widely used in clinical and research settings. However, their reproducibility with a 16-myocardial segment model has not been examined in chronic coronary artery disease (CAD). We examined the short-term reproducibility of PET (H2O)-O-15 MBF and PET 13NH3 MBF in an animal model of chronic CAD. Methods: Twelve swine (mean weight +/- SID, 38 +/- 5 kg) underwent percutaneous placement of a copper stent in the mid circumflex coronary artery, resulting in an intense inflammatory fibrotic reaction with luminal stenosis at 4 wk. Each animal underwent repeated resting MBF measurements by PET (H2O)-O-15 and PET 13NH3. Attenuation-corrected images were analyzed using commercial software to yield absolute MBF (mL/min/g) in 16 myocardial segments. MBF was also normalized to the rate-pressure product (RPP). Results: By Bland-Altman reproducibility plots, the mean difference was 0.01 +/- 0.18 mL/min/g and 0.01 +/- 0.11 mL/min/g, with confidence limits of +/- 0.36 and +/- 0.22 mL/min/g for uncorrected regional PET (H2O)-O-15 MBF and for uncorrected regional PET 13NH3 MBF, respectively. The repeatability coefficient ranged from 0.09 to 0.43 mL/min/g for (H2O)-O-15 and from 0.09 to 0.18 mL/min/g for (NH3)-N-13 regional MBF. RPP correction did not improve reproducibility for either PET (H2O)-O-15 or PET 13NH3 MBF The mean difference in PET (H2O)-O-15 MBF was 0.03 +/- 0.14 mL/min/g and 0.02 +/- 0.19 mL/min/g for infarcted and remote regions, respectively, and in PET 13NH3 MBF was 0.03 +/- 0.11 mL/min/g and 0.00 +/- 0.09 mL/min/g for infarcted and remote regions, respectively. Conclusion: PET (H2O)-O-15 and PET 13NH3 resting MBF showed excellent reproducibility in a closed-chest animal model of chronic CAD. Resting PET (NH3)-N-13 MBF was more reproducible than resting PET (H2O)-O-15 MBF A high level of reproducibility was maintained in areas of lower flow with infarction for both isotopes.

Background: Positron emission tomography (PET) with fluorine-18 fluorodeoxyglucose (FDG) can be utilized to assess myocardial viability. The objective of this study was to assess FDG PET image quality during the hyperinsulinemic euglycemic clamp (HE clamp) in patients with and without diabetes referred for myocardial viability assessment.

Journal of Cardiovascular ElectrophysiologyVolume 13, Issue 2 p. 200-200 Unusual Response to Atrial Extrastimulus Testing STUART D. CHRISTENSON M.D., STUART D. CHRISTENSON M.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this authorBRIAN OLSHANSKY M.D., BRIAN OLSHANSKY M.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this authorKALYANAM SHIVKUMAR M.D., Ph.D., KALYANAM SHIVKUMAR M.D., Ph.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this author STUART D. CHRISTENSON M.D., STUART D. CHRISTENSON M.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this authorBRIAN OLSHANSKY M.D., BRIAN OLSHANSKY M.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this authorKALYANAM SHIVKUMAR M.D., Ph.D., KALYANAM SHIVKUMAR M.D., Ph.D. *Cardiac Electrophysiology Section, Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IowaSearch for more papers by this author First published: 12 August 2003 https://doi.org/10.1046/j.1540-8167.2002.00200.xCitations: 1 Address for correspondence: Kalyanam Shivkumar, M.D., Ph.D., Division of Cardiology, Department of Medicine, University of Iowa Hospitals and Clinics, 4426 B, JCP, 200 Hawkins Drive, Iowa City, IA 52242-1081. Fax: 319-384-6247; E-mail: kalyanam-shivkumar@uiowa.edu AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat No abstract is available for this article.Citing Literature Volume13, Issue2February 2002Pages 200-200 RelatedInformation