Jeffrey F. Smallhorn

Novel insights into RV adaptation and function in hypoplastic left heart syndrome between the first 2 stages of surgical palliation.

OBJECTIVESnThis study sought to examine the changes in ventricular function of hypoplastic left heart syndrome (HLHS) between the first 2 stages of surgical palliation.nnnBACKGROUNDnThe mortality risk between first and second stages of surgical palliation in HLHS remains high. Right ventricular (RV) dysfunction predicts mortality. Postulated mechanisms include a maladaptive contraction pattern, myocardial ischemia, or contraction asynchrony. Speckle tracking imaging allows accurate measurement of myocardial deformation without geometric assumptions.nnnMETHODSnProspective echocardiography pre-Norwood and pre-bidirectional cavopulmonary anastomosis (BCPA) examinations were performed in 20 HLHS patients, with comparisons made between stages. Measurements of ventricular function included: longitudinal/circumferential strain ratio, reflecting changes in contraction pattern; post-systolic strain index, a potential marker of myocardial ischemia; and mechanical dyssynchrony index. Relationships between echocardiographic variables and magnetic resonance imaging RV parameters before BCPA were examined.nnnRESULTSnBefore BCPA, myocardial contractility estimated by isovolumic acceleration and strain rate was reduced, paralleled by an increased in post-systolic strain index (p < 0.01). Right ventricular longitudinal/circumferential strain ratio decreased, becoming similar to a left ventricle-like contraction pattern, and this correlated with decreased mechanical dyssynchrony index (r = 0.65, p < 0.01), magnetic resonance imaging RV end-diastolic volume (r = 0.65, p < 0.05) and mass (r = 0.71, p < 0.01). Ventricular strain (r = -0.72, p < 0.01), strain rate (r = -0.85, p < 0.001), and mechanical dyssynchrony index (r = -0.73, p < 0.01) correlated linearly with magnetic resonance imaging-derived RV ejection fraction.nnnCONCLUSIONSnReduced RV contractility occurred before BCPA. RV with a left ventricle-like contraction pattern was associated with improved contraction synchrony as well as a reduction in RV size and mass in HLHS. The finding of increased post-systolic strain index before BCPA is novel and its potential link with myocardial ischemia warrants further investigation. RV strain, strain rate, and contraction synchrony measured by speckle tracking imaging correlated closely with ventricular function and might be useful for monitoring ventricular function in HLHS.

Normal Rotational, Torsion and Untwisting Data in Children, Adolescents and Young Adults

BACKGROUNDnLeft ventricular (LV) torsion and untwisting are important components of LV performance, but there is little information on the effect of age, particularly in younger populations.nnnMETHODSnLV rotation and LV rotation rate, torsion, recoiling, and untwisting were measured in normal subjects (n=111) aged 3 to 40 years (mean age, 19.3 years) using speckle-tracking imaging.nnnRESULTSnLV torsion increased with age because of the augmentation of apical LV rotation, but this disappeared when normalized by LV length. Although peak LV torsion and apical LV rotation increased with age, the normalized peak torsion rate decreased. As well, the peak untwisting rate decreased with age and was enhanced when normalized by LV length. Younger hearts demonstrated greater untwisting and recoiling of the apex during isovolumic relaxation and early diastole. The time difference between apical and basal events decreased with advancing age.nnnCONCLUSIONnThe heart maintains a constant LV torsion and LV rotation profile when normalized by length and cardiac cycle. Younger hearts tend to twist, untwist, and deform faster.

Two-Dimensional Versus Transthoracic Real-Time Three-Dimensional Echocardiography in the Evaluation of the Mechanisms and Sites of Atrioventricular Valve Regurgitation in a Congenital Heart Disease Population

BACKGROUNDnData are lacking on the utility of real-time three-dimensional (3D) echocardiography (RT3DE) in congenital abnormalities of the atrioventricular (AV) valves. The purpose of this study was to determine whether transthoracic RT3DE is superior to combined transthoracic echocardiography and two-dimensional (2D) transesophageal echocardiography in determining mechanisms and sites of AV valve regurgitation in congenital heart disease.nnnMETHODSnBetween January 2005 and November 2007, 48 consecutive patients were studied prior to AV valve repair (22 left AV valves and 26 tricuspid valves) using 2D transthoracic echocardiography, 2D transesophageal echocardiography, and transthoracic RT3DE. Ages ranged from 24 days to 30 years. The 2D data were reviewed by blinded observers, and the real-time 3D data by a separate observer. In all patients, surgical findings were documented by a surgical report, while in 40, video recordings were also available. Surgical findings were used as the reference standard for structural abnormalities; RT3DE was the reference standard for the site of AV valve regurgitation.nnnRESULTSnCompared with 2D echocardiography, RT3DE provided superior detail of the mural leaflet and anterior commissural abnormalities for the left AV valve. For the tricuspid valve, improved detection of leaflet abnormalities, prolapse of the anterior and posterior leaflets, and commissural pathology was observed by RT3DE. Apart from a central location, surgical saline testing correlated poorly with jet location on RT3DE.nnnCONCLUSIONnRT3DE provides complementary information as to the mechanisms and sites of AV valve failure in congenital heart disease.

Real-Time 3-Dimensional Echocardiography Provides New Insight Into Mechanisms of Tricuspid Valve Regurgitation in Patients With Hypoplastic Left Heart Syndrome

Background— Tricuspid regurgitation in hypoplastic left heart syndrome has an impact on outcome, but its mechanisms remain unclear. Methods and Results— Real-time 3-dimensional echocardiography was performed in 35 patients with hypoplastic left heart syndrome (age, 1 month to 10 years; 10 after first-stage Norwood, 12 after superior cavopulmonary shunt, 13 after Fontan). From the 3-dimensional data set, we marked the annulus in systole and diastole. At mid systole, we marked the location of the papillary muscle tip and point of chordal attachment to the leaflet. We traced the surfaces of the tricuspid valve leaflets and measured the volume of leaflet prolapse, tethering, annular and septal leaflet areas, and papillary muscle position. Seventeen patients had moderate tricuspid regurgitation (prolapse, 7; tethered leaflets, 7) and 18 mild (prolapse, 0; tethered leaflets, 7). Multiple linear regression analysis revealed that moderate tricuspid regurgitation is associated with leaflet tethering and prolapse; that in hypoplastic left heart syndrome with tethered leaflets, the papillary muscle is displaced laterally and the tricuspid annulus is more planar; and that enlargement of the annulus at mid systole, small septal leaflet area, and age affect the degree of prolapse. Conclusion— In hypoplastic left heart syndrome, moderate tricuspid regurgitation may be associated with increasing age, geometrical changes of the annulus, leaflet prolapse, lateral papillary muscle displacement, and subsequent leaflet tethering, as well as a smaller septal leaflet.

Serial Assessment of Right Ventricular Volume and Function in Surgically Palliated Hypoplastic Left Heart Syndrome Using Real-Time Transthoracic Three-Dimensional Echocardiography

BACKGROUNDnRight ventricular (RV) failure is a major cause of morbidity and mortality in patients with hypoplastic left heart syndrome (HLHS), but the longitudinal course of RV volumes through staged palliation (SP) has not been previously investigated. The aim of this study was to evaluate RV volume and function longitudinally through SP of HLHS using real-time three-dimensional echocardiography.nnnMETHODSnA total of 18 subjects with HLHS were prospectively studied at four time points from diagnosis through stage 2 (SP2). Real-time three-dimensional echocardiographic full-volume data sets were acquired in high-frame rate mode with electrocardiographic gating. Volumetric and functional analyses were performed using a semiautomatic contour detection algorithm. Eighteen age-matched and sex-matched normal infants (aged 0-6 months) were studied at comparable time points as controls.nnnRESULTSnPresurgical examinations (pre-stage 1 [SP1]; n = 18) were performed at a mean age of 4 days, post-SP1 examinations (n = 17) at a mean age of 20 days, pre-SP2 examinations (n = 14) at a mean age of 4.6 months, and post-SP2 examinations (n = 14) at a mean age of 5.5 months, constituting a total of 63 examinations. The mean values of RV end-diastolic volume indexed to body surface area (EDVi) at the four time points were 87 ± 30, 104 ± 39, 112 ± 34, and 102 ± 35 mL/m(2), respectively. There was an increase in EDVi (P = .024) from pre-SP1 to post-SP1 but no significant change between post-SP1 and pre-SP2. The decrease in EDVi after SP2 did not reach statistical significance. Mean RV ejection fractions (EFs) were 50 ± 5%, 45 ± 5%, 46 ± 5%, and 38 ± 4%, respectively. There was a trend toward decreasing EF throughout SP, with statistically significant decreases from pre-SP1 to post-SP1 (P = .003) and from pre-SP2 to post-SP2 (P < .001). In normal infants, the mean RV EDVi was 50 ± 10 mL/m(2) (approximately half that of patients with HLHS), and the mean EF was 51 ± 3%. There was good interobserver agreement for EDVi, end-systolic volume indexed to body surface area, and EF.nnnCONCLUSIONSnReal-time three-dimensional echocardiography is a reproducible means for evaluating RV volumes and EFs in patients with HLHS. Indexed RV diastolic volume remains stable to slightly increased, and RV EF deteriorates as the first two stages of surgical palliation are accomplished. The findings of this study highlight the adverse physiology of HLHS, which deteriorates even among early survivors despite SP.

Defining Left Ventricular Apex-to-Base Twist Mechanics Computed From High-Resolution 3D Echocardiography: Validation Against Sonomicrometry

OBJECTIVESnTo compute left ventricular (LV) twist from 3-dimensional (3D) echocardiography.nnnBACKGROUNDnLV twist is a sensitive index of cardiac performance. Conventional 2-dimensional based methods of computing LV twist are cumbersome and subject to errors.nnnMETHODSnWe studied 10 adult open-chest pigs. The pre-load to the heart was altered by temporary controlled occlusion of the inferior vena cava, and myocardial ischemia was produced by ligating the left anterior descending coronary artery. Full-volume 3D loops were reconstructed by stitching of pyramidal volumes acquired from 7 consecutive heart beats with electrocardiography gating on a Philips IE33 system (Philips Medical Systems, Andover, Massachusetts) at baseline and other steady states. Polar coordinate data of the 3D images were entered into an envelope detection program implemented in MatLab (The MathWorks, Inc., Natick, Massachusetts), and speckle motion was tracked using nonrigid image registration with spline-based transformation parameterization. The 3D displacement field was obtained, and rotation at apical and basal planes was computed. LV twist was derived as the net difference of apical and basal rotation. Sonomicrometry data of cardiac motion were also acquired from crystals anchored to epicardium in apical and basal planes at all states.nnnRESULTSnThe 3D dense tracking slightly overestimated the LV twist, but detected changes in LV twist at different states and showed good correlation (r = 0.89) when compared with sonomicrometry-derived twist at all steady states. In open chest pigs, peak cardiac twist was increased with reduction of pre-load from inferior vena cava occlusion from 6.25 degrees +/- 1.65 degrees to 9.45 degrees +/- 1.95 degrees . With myocardial ischemia from left anterior descending coronary artery ligation, twist was decreased to 4.90 degrees +/- 0.85 degrees (r = 0.8759).nnnCONCLUSIONSnDespite lower spatiotemporal resolution of 3D echocardiography, LV twist and torsion can be computed accurately.

Single Right Ventricles Have Impaired Systolic and Diastolic Function Compared to Those of Left Ventricular Morphology

BACKGROUNDnDifferences in single right ventricle (SRV) and single left ventricles (SLV) function are poorly described, although myocardial dysfunction is an important risk factor for morbidity and mortality. The aims of this study were to compare function between patients with SRVs and those with SLVs using newer echocardiographic techniques and to determine differences across staged palliation.nnnMETHODSnIn this cross-sectional study comparing 30 patients with SRVs and 30 with SLVs of similar ages (2.5 ± 1.7 vs 2.6 ± 1.6 years), patients were matched for surgical stage (20 pre-bidirectional cavopulmonary anastomosis, 20 pre-Fontan, and 20 post-Fontan patients). Circumferential and longitudinal strain, strain rate (SR), early diastolic SR, postsystolic strain index, and myocardial dyssynchrony index were measured. Comparisons between SRV and SLV parameters were made as a whole group and by subanalysis at each surgical stage.nnnRESULTSnPatients with SRVs had reduced systolic SRs (circumferential: -1.0%/sec vs -1.2%/sec, Pxa0= .01; longitudinal: -1.1%/sec vs -1.3%/sec, Pxa0= .002), reduced early diastolic SRs (circumferential: 1.4%/sec vs 1.9%/sec, Pxa0= .03; longitudinal: 1.6%/sec vs 2.2%/sec, Pxa0= .001), and increased circumferential postsystolic strain indexes (8% vs 0%, P < .0001). Subanalysis at each surgical stage showed that the greatest disparity in systolic parameters occurred before bidirectional cavopulmonary anastomosis (longitudinal SR, Pxa0= .009; postsystolic strain index, Pxa0= .005) and that parity was regained after the Fontan procedure, while traditional diastolic parameters (E velocity, Pxa0= .004; E/E ratio, Pxa0= .0003) were reduced in patients with SRVs after the Fontan procedure.nnnCONCLUSIONSnThe SRV has reduced contractility and diastolic function compared with the SLV. Ventricular systolic performance in patients with SRVs was poorest before bidirectional cavopulmonary anastomosis, while differences in diastolic function were more prominent after Fontan completion.

Quantitative real-time three-dimensional echocardiography provides new insight into the mechanisms of mitral valve regurgitation post-repair of atrioventricular septal defect.

BACKGROUNDnMechanisms of mitral valve regurgitation after atrioventricular septal defect repair are unclear.nnnMETHODSnTo gain further insight into mitral valve regurgitation, real-time three-dimensional echocardiography was performed in 53 patients after atrioventricular septal defect repair (30 partial and 23 complete) and 40 controls. Mitral valve {x, y, z} coordinates from the annulus, leaflet surface, papillary muscle, and chordal attachments were recorded. Vena contracta area of the regurgitant jet(s) and volume of leaflet prolapse and tethering were measured.nnnRESULTSnTwenty-three patients had mild (group 1) and 30 moderate (group 2) mitral valve regurgitation. Patients in both groups 1 and 2 had more circular annuli than controls. Annular area was greater in group 2 than in group 1 and controls (P < .01). Group 2 had more frequent segmental prolapse in the superior-mural leaflet segment. The anterolateral papillary muscle was more laterally displaced in group 2 than in controls and group 1 at end-diastole (Pxa0= .01 and Pxa0= .05) and formed a more acute angle with the mitral valve annulus than in controls or group 1 (Pxa0= .01).nnnCONCLUSIONSnIn patients with atrioventricular septal defects, significant mitral valve regurgitation is associated with leaflet prolapse, larger annular area, and lateral papillary muscle displacement.

Evaluation of Atrioventricular Septal Defects by Three-Dimensional Echocardiography: Benefits of Navigating the Third Dimension

Atrioventricular septal defects comprise a disease spectrum characterized by deficient atrioventricular septation, with several common features seen in all affected hearts and variability in atrioventricular valve morphology and interatrial and interventricular communications. Atrioventricular septal defects are among the more common defects encountered by pediatric cardiologists and echocardiographers. Despite advances in understanding, standard two-dimensional echocardiography may not be the optimal method for the morphologic and functional evaluation of this lesion, particularly malformations of the atrioventricular valve(s). In this review, the authors summarize the role of three-dimensional echocardiography in the diagnostic evaluation of atrioventricular septal defects.

The Assessment of Atrial Function in Single Ventricle Hearts from Birth to Fontan: A Speckle-Tracking Study by Using Strain and Strain Rate

BACKGROUNDnSingle ventricle (SV) exercise performance is impaired and limited by reduced ventricular preload reserve. The atrium modulates ventricular filling, and enhancement of atrial compliance can increase cardiac performance. We aimed to study atrial mechanics in SV hearts across staged surgical palliation compared with healthy children by using novel speckle-tracking echocardiography techniques.nnnMETHODSnA cross-sectional study of 81 patients with SV (1 day to 6.5 years) at 4 stages of surgical palliation (presurgery, 22; prebidirectional cavopulmonary anastomosis, 23; pre-Fontan, 22; post-Fontan, 14). The dominant atrium was assessed with speckle-tracking echocardiography for active (εact), conduit (εcon), and reservoir (εres) strain; strain rate (SR); and εact/εres ratio before each stage of surgical palliation. Findings were compared with the left atrium of 51 healthy children (1 day to 5.5 years).nnnRESULTSnSingle ventricle atrial size was increased (P < .01), and atrial εres was decreased (P < .01) compared with healthy controls. SV atrial εcon (P < .01) and SRcon (P < .0001) was decreased, increased εact persisted (P < .05), and εact/εres was increased (P < .001) between surgical stages. Although the expected maturational trend of increasing εcon, decreasing εact, and εact/εres occurred in SV, they lagged behind healthy maturational changes (P < .0001).nnnCONCLUSIONnSingle ventricle atrium is dilated, has deceased compliance, decreased early diastolic emptying, and increased reliance on active atrial contraction for ventricular filling. This deviates from normal early childhood maturational changes and appears to parallel those of an atrium facing early ventricular diastolic dysfunction.