1
|
Moustafa AT, Tang ASL, Khan HR. Conduction system pacing on track to replace CRT? Review of current evidence and prospects of conduction system pacing. Front Cardiovasc Med 2023; 10:1220709. [PMID: 37649666 PMCID: PMC10463741 DOI: 10.3389/fcvm.2023.1220709] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2023] [Accepted: 07/31/2023] [Indexed: 09/01/2023] Open
Abstract
Conduction system pacing (CSP) has been emerging over the last decade as a pacing option instead of conventional right ventricular (RV) pacing and biventricular (BiV) pacing. Numerous case reports, some observational studies and a few randomized control trials have looked at optimum pacing strategies for heart failure (HF) with left bundle branch block (LBBB) or cases where left ventricular (LV) dysfunction is anticipated due to chronic RV pacing (RVP). Evolution of pacing strategies from standard RVP to septal RVP, BiV pacing and now CSP have shown improving hemodynamic responses and possible ease of implantation of CSP systems. In this review article, we review the literature on the evolution of CSP and common scenarios where it might be beneficial.
Collapse
Affiliation(s)
| | | | - Habib Rehman Khan
- Schulich School of Medicine and Dentistry, University of Western Ontario, London, ON, Canada
| |
Collapse
|
2
|
Salatzki J, Fischer T, Riffel J, André F, Hirschberg K, Ochs A, Hund H, Müller-Hennessen M, Giannitsis E, Friedrich MG, Scholz E, Frey N, Katus HA, Ochs M. Presence of contractile impairment appears crucial for structural remodeling in idiopathic left bundle-branch block. J Cardiovasc Magn Reson 2021; 23:39. [PMID: 33789682 PMCID: PMC8015193 DOI: 10.1186/s12968-021-00731-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Accepted: 02/08/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND To differentiate effects of ventricular asynchrony from an underlying hypocontractile cardiomyopathy this study aimed to enhance the understanding of functional impairment and structural remodeling in idiopathic left bundle-branch block (LBBB). We hypothesize, that functional asynchrony with septal flash volume effects alone might not entirely explain the degree of functional impairment. Hence, we suggest the presence of a superimposed contractile cardiomyopathy. METHODS In this retrospective study, 53 patients with idiopathic LBBB were identified and matched to controls with and without cardiovascular risk factors. Cardiovascular magnetic resonance (CMR) was used to evaluate cardiac function, volumes and myocardial fibrosis using native T1 mapping and late gadolinium enhancement (LGE). Septal flash volume was assessed by CMR volumetric measurements and allowed to stratify patients with systolic dysfunction solely due to isolated ventricular asynchrony or superimposed contractile impairment. RESULTS Reduced systolic LV-function, increased LV-volumes and septal myocardial fibrosis were found in patients with idiopathic LBBB compared to healthy controls. LV-volumes increased and systolic LV-function declined with prolonged QRS duration. Fibrosis was typically located at the right ventricular insertion points. Subgroups with superimposed contractile impairment appeared with pronounced LV dilation and increased fibrotic remodeling compared to individuals with isolated ventricular asynchrony. CONCLUSIONS The presence of superimposed contractile impairment in idiopathic LBBB is crucial to identify patients with enhanced structural remodeling. This finding suggests an underlying cardiomyopathy. Future studies are needed to assess a possible prognostic impact of this entity and the development of heart failure. TRIAL REGISTRATION This study was retrospectively registered.
Collapse
Affiliation(s)
- Janek Salatzki
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany.
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany.
| | - Theresa Fischer
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Johannes Riffel
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Florian André
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Kristóf Hirschberg
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- Semmelweis University Heart and Vascular Center, Budapest, Hungary
| | - Andreas Ochs
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Hauke Hund
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
| | - Matthias Müller-Hennessen
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Evangelos Giannitsis
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Matthias G Friedrich
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
- Division of Cardiology, Departments of Medicine and Diagnostic Radiology, Mc-Gill University Health Centre, Montreal, Canada
| | - Eberhard Scholz
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Norbert Frey
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Hugo A Katus
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| | - Marco Ochs
- Department of Cardiology, Angiology and Pneumology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120, Heidelberg, Germany
- DZHK (German Centre for Cardiovascular Research), Partner site Heidelberg, Heidelberg, Germany
| |
Collapse
|
3
|
Akhtari S, Chuang ML, Salton CJ, Berg S, Kissinger KV, Goddu B, O’Donnell CJ, Manning WJ. Effect of isolated left bundle-branch block on biventricular volumes and ejection fraction: a cardiovascular magnetic resonance assessment. J Cardiovasc Magn Reson 2018; 20:66. [PMID: 30231875 PMCID: PMC6146610 DOI: 10.1186/s12968-018-0457-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 05/08/2018] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Left bundle branch block (LBBB) is associated with abnormal left ventricular (LV) contraction, and is frequently associated with co-morbid cardiovascular disease, but the effect of an isolated (i.e. in the absence of cardiovascular dissease) LBBB on biventricular volumes and ejection fraction (EF) is not well characterized. The objective of this study was to compare LV and right ventricular (RV) volumes and EF in adults with an isolated LBBB to matched healthy controls and to population-derived normative values, using cardiovascular magnetic resonance (CMR) imaging. METHODS We reviewed our clinical echocardiography database and the Framingham Heart Study Offspring cohort CMR database to identify adults with an isolated LBBB. Age-, sex-, hypertension-status, and body-surface area (BSA)-matched controls were identified from the Offspring cohort. All study subjects were scanned using the same CMR hardware and imaging sequence. Isolated-LBBB cases were compared with matched controls using Wilcoxon paired signed-rank test, and to normative reference values via Z-score. RESULTS Isolated-LBBB subjects (n = 18, 10F) ranged in age from 37 to 82 years. An isolated LBBB was associated with larger LV end-diastolic and end-systolic volumes (both p < 0.01) and lower LVEF (56+/- 7% vs. 68+/- 6%; p <0.001) with similar myocardial contraction fraction. LVEF in isolated LBBB was nearly two standard deviations (Z = - 1.95) below mean sex and age-matched group values. LV stroke volume, cardiac output, and mass, and all RV parameters were similar (p = NS) between the groups. CONCLUSIONS Adults with an isolated LBBB have greater LV volumes and markedly reduced LVEF, despite the absence of overt cardiovascular disease. These data may be useful toward the clinical interpretation of imaging studies performed on patients with an isolated LBBB.
Collapse
MESH Headings
- Adult
- Aged
- Aged, 80 and over
- Bundle-Branch Block/complications
- Bundle-Branch Block/diagnostic imaging
- Bundle-Branch Block/physiopathology
- Case-Control Studies
- Databases, Factual
- Female
- Humans
- Hypertrophy, Left Ventricular/diagnostic imaging
- Hypertrophy, Left Ventricular/etiology
- Hypertrophy, Left Ventricular/physiopathology
- Magnetic Resonance Imaging
- Male
- Middle Aged
- Myocardial Contraction
- Predictive Value of Tests
- Stroke Volume
- Ventricular Dysfunction, Left/diagnostic imaging
- Ventricular Dysfunction, Left/etiology
- Ventricular Dysfunction, Left/physiopathology
- Ventricular Function, Left
- Ventricular Function, Right
Collapse
Affiliation(s)
- Shadi Akhtari
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
| | - Michael L. Chuang
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
- The NHLBI’s Framingham Heart Study, Framingham, MA USA
| | - Carol J. Salton
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
| | - Sophie Berg
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
| | - Kraig V. Kissinger
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
| | - Beth Goddu
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
| | - Christopher J. O’Donnell
- The NHLBI’s Framingham Heart Study, Framingham, MA USA
- Cardiology Section, Veterans Affairs Healthcare System, Boston, MA USA
| | - Warren J. Manning
- Department of Medicine, Cardiovascular Division, Beth Israel Deaconess Medical Center, Harvard Medical School, 330 Brookline Avenue, Boston, MA 02215 USA
- Department of Radiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA USA
| |
Collapse
|
4
|
Lu X, Yang R, Xie Q, Ou S, Zha Y, Wang D. Nonrigid registration with corresponding points constraint for automatic segmentation of cardiac DSCT images. Biomed Eng Online 2017; 16:39. [PMID: 28351368 PMCID: PMC5370472 DOI: 10.1186/s12938-017-0323-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Accepted: 02/10/2017] [Indexed: 12/01/2022] Open
Abstract
Background Dual-source computed tomography (DSCT) is a very effective way for diagnosis and treatment of heart disease. The quantitative information of spatiotemporal DSCT images can be important for the evaluation of cardiac function. To avoid the shortcoming of manual delineation, it is imperative to develop an automatic segmentation technique for 4D cardiac images. Methods In this paper, we implement the heart segmentation-propagation framework based on nonrigid registration. The corresponding points of anatomical substructures are extracted by using the extension of n-dimensional scale invariant feature transform method. They are considered as a constraint term of nonrigid registration using the free-form deformation, in order to restrain the large variations and boundary ambiguity between subjects. Results We validate our method on 15 patients at ten time phases. Atlases are constructed by the training dataset from ten patients. On the remaining data the median overlap is shown to improve significantly compared to original mutual information, in particular from 0.4703 to 0.5015 (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$ p = 5.0 \times 10^{ - 4} $$\end{document}p=5.0×10-4) for left ventricle myocardium and from 0.6307 to 0.6519 (\documentclass[12pt]{minimal}
\usepackage{amsmath}
\usepackage{wasysym}
\usepackage{amsfonts}
\usepackage{amssymb}
\usepackage{amsbsy}
\usepackage{mathrsfs}
\usepackage{upgreek}
\setlength{\oddsidemargin}{-69pt}
\begin{document}$$ p = 6.0 \times 10^{ - 4} $$\end{document}p=6.0×10-4) for right atrium. Conclusions The proposed method outperforms standard mutual information of intensity only. The segmentation errors had been significantly reduced at the left ventricle myocardium and the right atrium. The mean surface distance of using our framework is around 1.73 mm for the whole heart.
Collapse
Affiliation(s)
- Xuesong Lu
- College of Biomedical Engineering, South-Central University for Nationalities, Wuhan, 430074, People's Republic of China
| | - Rongqian Yang
- School of Materials Science and Engineering, South China University of Technology, Guangzhou, 510006, People's Republic of China.
| | - Qinlan Xie
- College of Biomedical Engineering, South-Central University for Nationalities, Wuhan, 430074, People's Republic of China
| | - Shanxing Ou
- Radiology Department, Guangzhou General Hospital of Guangzhou Military Area Command, Guangzhou, 510010, People's Republic of China
| | - Yunfei Zha
- Department of Radiology, Remin Hospital of Wuhan University, Wuhan, 430060, People's Republic of China
| | - Defeng Wang
- Research Center for Medical Image Computing, Department of Imaging and Interventional Radiology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China. .,Shenzhen Research Institute, The Chinese University of Hong Kong, Shenzhen, China.
| |
Collapse
|
5
|
Cardiovascular magnetic resonance features of mechanical dyssynchrony in patients with left bundle branch block. Int J Cardiovasc Imaging 2016; 32:1427-1438. [PMID: 27306621 DOI: 10.1007/s10554-016-0925-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 06/02/2016] [Indexed: 10/21/2022]
Abstract
Patients with left bundle branch block (LBBB) can exhibit mechanical dyssynchrony which may contribute to heart failure; such patients may benefit from cardiac resynchronization treatment (CRT). While cardiac magnetic resonance imaging (CMR) has become a common part of heart failure work-up, CMR features of mechanical dyssynchrony in patients with LBBB have not been well characterized. This study aims to investigate the potential of CMR to characterize mechanical features of LBBB. CMR examinations from 43 patients with LBBB on their electrocardiogram, but without significant focal structural abnormalities, and from 43 age- and gender-matched normal controls were retrospectively reviewed. The following mechanical features of LBBB were evaluated: septal flash (SF), apical rocking (AR), delayed aortic valve opening measured relative to both end-diastole (AVOED) and pulmonic valve opening (AVOPVO), delayed left-ventricular (LV) free-wall contraction, and curvatures of the septum and LV free-wall. Septal displacement curves were also generated, using feature-tracking techniques. The echocardiographic findings of LBBB were also reviewed in those subjects for whom they were available. LBBB was significantly associated with the presence of SF and AR; within the LBBB group, 79 % had SF and 65 % had AR. Delayed AVOED, AVOPVO, and delayed LV free-wall contraction were significantly associated with LBBB. AVOED and AVOPVO positively correlated with QRS duration and negatively correlated with ejection fraction. Hearts with electrocardiographic evidence of LBBB showed lower septal-to-LV free-wall curvature ratios at end-diastole compared to normal controls. CMR can be used to identify and evaluate mechanical dyssynchrony in patients with LBBB. None of the normal controls showed the mechanical features associated with LBBB. Moreover, not all patients with LBBB showed the same degree of mechanical dyssynchrony, which could have implications for CRT.
Collapse
|
6
|
Saporito S, van Assen HC, Houthuizen P, Aben JPMM, Strik M, van Middendorp LB, Prinzen FW, Mischi M. Assessment of left ventricular mechanical dyssynchrony in left bundle branch block canine model: Comparison between cine and tagged MRI. J Magn Reson Imaging 2016; 44:956-63. [PMID: 26973138 DOI: 10.1002/jmri.25225] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 02/23/2016] [Indexed: 11/09/2022] Open
Abstract
PURPOSE To compare cine and tagged magnetic resonance imaging (MRI) for left ventricular dyssynchrony assessment in left bundle branch block (LBBB), using the time-to-peak contraction timing, and a novel approach based on cross-correlation. MATERIALS AND METHODS We evaluated a canine model dataset (n = 10) before (pre-LBBB) and after induction of isolated LBBB (post-LBBB). Multislice short-axis tagged and cine MRI images were acquired using a 1.5 T scanner. We computed contraction time maps by cross-correlation, based on the timing of radial wall motion and of circumferential strain. Finally, we estimated dyssynchrony as the standard deviation of the contraction time over the different regions of the myocardium. RESULTS Induction of LBBB resulted in a significant increase in dyssynchrony (cine: 13.0 ± 3.9 msec for pre-LBBB, and 26.4 ± 5.0 msec for post-LBBB, P = 0.005; tagged: 17.1 ± 5.0 msec at for pre-LBBB, and 27.9 ± 9.8 msec for post-LBBB, P = 0.007). Dyssynchrony assessed by cine and tagged MRI were in agreement (r = 0.73, P = 0.0003); differences were in the order of time difference between successive frames of 20 msec (bias: -2.9 msec; limit of agreement: 10.1 msec). Contraction time maps were derived; agreement was found in the contraction patterns derived from cine and tagged MRI (mean difference in contraction time per segment: 3.6 ± 13.7 msec). CONCLUSION This study shows that the proposed method is able to quantify dyssynchrony after induced LBBB in an animal model. Cine-assessed dyssynchrony agreed with tagged-derived dyssynchrony, in terms of magnitude and spatial direction. J. MAGN. RESON. IMAGING 2016;44:956-963.
Collapse
Affiliation(s)
- Salvatore Saporito
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands.
| | - Hans C van Assen
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Patrick Houthuizen
- Department of Cardiology, Catharina Hospital Eindhoven, Eindhoven, the Netherlands
| | | | - Marc Strik
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
| | - Lars B van Middendorp
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
| | - Frits W Prinzen
- Department of Physiology, Maastricht University, Cardiovascular Research Institute Maastricht, Maastricht, the Netherlands
| | - Massimo Mischi
- Department of Electrical Engineering, Eindhoven University of Technology, Eindhoven, the Netherlands
| |
Collapse
|
7
|
Rathod RH, Prakash A, Kim YY, Germanakis IE, Powell AJ, Gauvreau K, Geva T. Cardiac magnetic resonance parameters predict transplantation-free survival in patients with fontan circulation. Circ Cardiovasc Imaging 2014; 7:502-9. [PMID: 24619103 DOI: 10.1161/circimaging.113.001473] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Several clinical risk factors for death and heart transplantation have been identified in patients with Fontan circulation. It is unknown whether cardiac magnetic resonance (CMR) measurements of ventricular size and function are independently associated with these outcomes and further improve risk stratification. METHODS AND RESULTS Data on patients with Fontan circulation who had a CMR study from January 2002 to January 2011 were retrospectively reviewed. The end point was time to death or listing for heart transplantation after the CMR study. The median age of the 215 patients was 18.3 years (25th, 75th percentiles: 14, 26) with a median age at Fontan of 3.6 years (2.3, 7.1). During a median post-CMR follow-up period of 4.1 years (2.6, 6.2), 24 patients (11%) reached the end point: 20 deaths, 3 transplantations, and 1 transplantation listing. In a multivariable Cox regression model with clinical parameters only, protein-losing enteropathy was associated with death or listing for transplant. A multivariable model, including clinical and CMR parameters, showed that in addition to protein-losing enteropathy, ventricular indexed end-diastolic volume >125 mL/body surface area raised to the 1.3 power was associated with the endpoint. A likelihood-ratio test comparing the 2 models showed that the addition of indexed end-diastolic volume resulted in a significantly improved end point prediction (P<0.001)-C-index increased from 0.63 to 0.79. CONCLUSIONS CMR-derived ventricular indexed end-diastolic volume is an independent predictor of death or transplant in patients late after the Fontan operation and adds incremental value over clinical symptoms alone for risk stratification.
Collapse
Affiliation(s)
- Rahul H Rathod
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA.
| | - Ashwin Prakash
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Yuli Y Kim
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Ioannis E Germanakis
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Andrew J Powell
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Kimberlee Gauvreau
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| | - Tal Geva
- From the Department of Cardiology, Boston Children's Hospital, Boston, MA; and Department of Pediatrics, Harvard Medical School, Boston, MA
| |
Collapse
|