Standardization and validation of neoLVOT assessment using three-dimensional trans-esophageal echocardiography before trans-catheter mitral valve replacement.

BACKGROUND: Trans-catheter mitral valve replacement (TMVR) procedures had emerged as an alternative solution for patients who are at high risk for mitral valve surgery. Although cardiac computed tomography (CT) remains the standard method for procedural planning, there is no full agreement on the best systolic phase for quantitation of the neoLVOT. Furthermore, a new three-dimensional trans-esophageal echocardiography (3DTEE) based software was developed to serve as filter and or an alternative for patients who cannot have CT due to any contraindication. AIM: To determine the systolic phase of the cardiac cycle that shows the narrowest NeoLVOT area in order to standardize the way of using these software and then to validate the 3DTEE-based software against the CT-based one as a gold standard, in mitral valve annulus (MA) and NeoLVOT assessment. METHODS: A single center, observational, retrospective study. Initially, a sample of 20 patients (age 62 ± 4 years, 70% men) had CT-based analysis at mid-diastole (80%), early-systole (10%), mid-systole (20%), late-systole (30%-40%), in order to detect the best systolic phase at which the neoLVOT area is the narrowest after TMVR. Then, the end systolic phase was standardized for the analysis of 49 patients (age 57 ± 6 years, 60% men), using both the commercially available CT-based software and the newly available 3DTEE-based software (3mensio Structural Heart, Pie Medical Imaging, The Netherlands). The 3DTEE derived parameters were compared with the gold standard CT-based measurements. RESULTS: The neoLVOT area was significantly narrower at end-systole (224 ± 62 mm2), compared to early-systole (299 ± 70 mm2) and mid-systole (261 ± 75 mm2), (p = .005). Excellent correlation was found between 3DTEE and CT measurements for MA AP diameter (r = .96), IC diameter (r = .92), MA area (r = .96), MA perimeter (r = .94) and NeoLVOT area (r = .96), (all p-values < .0001). Virtual valve sizing was based on annulus measurement and was identical between CT and 3DTEE. Interobserver and intraobserver agreements were excellent for all the measurements with ICCs > .80. CONCLUSIONS: End-systole is the phase that shows the narrowest neoLVOT and hence should be the standard phase used during the analysis. The 3DTEE based analysis using this new software is reliable compared to the CT-based analysis and can be serve as an alternative analysis tool in patients who cannot have CT for any clinical contraindication or as a screening test and/or filter for all patients before proceeding to a detailed CT scan.

A quantitative assessment of aorta root rotation in patients with tetralogy of Fallot evaluated by MSCT.

Lack of conal rotation and conal malseptation is a characteristic anatomical feature for TOF which lead to dextroposed position of aorta and significant RVOT narrowing. The quantitative assessment of these anatomical features using modern cardiac imaging modality has been rarely discussed in the literature. All TOF scanned had in our center from 2013 till 2019 were included. The angle of aortic root rotation was recorded by measuring the angle between a line connecting the midpoint of the non-coronary sinus to the anterior commissure and another line along the interatrial septum. Rotation angles were correlated with proximal main pulmonary artery (MPA) size indexed to BSA. 287 TOF patients were included, 258 patients (91%) had TOF with pulmonary stenosis (TOF-PS) including 138 male (54%), median age 2 years (2 months-40 years), and 29 patients (9%) had TOF with pulmonary atresia (TOF-PA) including 17 male (59%), median age 5 years (1 m-33 years). The whole cases demonstrated clockwise rotation of the aortic root. The mean rotation angle in TOF-PS group was 52.6 ± 20.9° and in TOF-PA group was 64.9 ± 13.9°. Proximal MPA diameter was 11.1 ± 5.9 mm/m2. There was a significant negative correlation between aortic root rotation angle and proximal MPA diameter (r = - 0.262, P = 0.000). The rotation angle of aortic root was significantly higher in TOF-PA compared to TOF-PS (64.9 ± 13.9° vs. 52.6 ± 20.9°, P = 0.001, respectively). MSCT provide a quantitative measurement methodology of conal malseptation and its effect in TOF patients. There is a clockwise rotation angle of the aortic root in TOF patients that correlates negatively with proximal MPA size. TOF-PA have a larger rotation angle of aortic root.

Multiparametric Rest and Dobutamine Stress Magnetic Resonance in Assessment of Myocardial Viability.

BACKGROUND: MR feature-tracking (FT) is a novel technique that quantitatively calculates myocardial strain and can assess myocardial viability. PURPOSE: To evaluate the feasibility of FT at rest and with low-dose dobutamine (LDD), visual assessment of contractility with LDD and left ventricle (LV) end-diastolic wall thickness (EDWT) in the assessment of viability in ischemic cardiomyopathy (ICM) patients compared to delayed gadolinium enhancement (DGE). STUDY TYPE: Prospective. SUBJECTS: Thirty ICM patients and 30 healthy volunteers. FIELD STRENGTH/SEQUENCES: A 1.5 T with balanced steady-state free precession (bSSFP) cine and phase-sensitive inversion prepared segmented gradient echo sequences. ASSESSMENT: LDD (5 µg/kg/min and 10 µg/kg/min) was administered in the patient group. LV was divided into 16 segments and MR-FT was derived from bSSFP cine images using dedicated software. Viable segments were defined as those with a dobutamine-induced increase in resting MR-FT values >20%, a dobutamine-induced increase in systolic wall thickening ≥2 mm by visual assessment, ≤50% fibrosis on DGE, and resting EDWT ≥5.5 mm. STATISTICAL TESTS: One-way analysis of variance (ANOVA), two-sampled t-test, paired samples t-test, and receiver operating characteristic (ROC) curve analysis. A P value < 0.05 was considered statistically significant. RESULTS: Resting peak global circumferential (Ecc) and radial (Err) strains were significantly impaired in patients compared to controls (-11.7 ± 7.9 vs. -20.1 ± 5.7 and 19.7 ± 13.9 vs. 32.7 ± 15.4, respectively). Segments with no DGE (n = 354) and ≤ 50% (n = 38) DGE showed significant improvement of both Ecc and Err with LDD while segments with >50% DGE (n = 88) showed no improvement. In comparison to viable and nonviable segments identified by reference-standard DGE, the sensitivity, specificity, and diagnostic accuracy of the four methods were: 74%, 92%, and 89%, respectively, for Ecc; 70%, 89%, and 86%, respectively, for Err; 67%, 88%, and 84% for visual assessment; and 39%, 90%, and 80% for EDWT. DATA CONCLUSION: Quantitative assessment of MR-FT, along with EDWT and qualitative visual assessment of myocardial contractility with LDD, are feasible alternative methods for the assessment of myocardial viability with moderate sensitivity and high specificity. LEVEL OF EVIDENCE: 1 TECHNICAL EFFICACY: Stage: 2.

Assessment of flow pattern of right ventricle outflow and pulmonary arteries in surgically corrected tetralogy of Fallot patients by four-dimensional cardiac magnetic resonance flow.

BACKGROUND: The most common post-surgical complication of tetralogy of Fallot (TOF) is pulmonary regurgitation (PR) which can lead to right ventricle (RV) dysfunction/failure. Cardiac magnetic resonance (CMR) is the imaging modality of choice to follow-up a repaired TOF. However, the conventional two-dimensional phase-contrast (2D-PC) flow usually underestimates PR as well as the pulmonary peak systolic velocity (PSV). Recently, four-dimensional (4D) CMR flow is introduced for more accurate quantitative flow assessment. This work aimed to compare between 4D-CMR and 2D-PC flow across the main (MPA), right (RPA), and left (LPA) pulmonary arteries (PAs) in surgically corrected TOF patients. RESULTS: This study was conducted on 20 repaired TOF patients (range 3-9 years, 50% males). All patients had CMR exam on 1.5T scanner. 4D-CMR and 2D-PC flows were obtained at the proximal segments of the MPA, RPA, and LPA. The stroke volume index (SVI), regurgitation fraction (RF), and PSV measured by 4D-CMR were compared to 2D-PC flow. The SVI across the PAs was nearly similar between both methods (P = 0.179 for MPA, 0.218 for RPA, and 0.091 for LPA). However, the RF was significantly higher by 4D-CMR in comparison to 2D-PC flow (P = 0.027 for MPA, 0.039 for RPA, and 0.046 for LPA). The PSV as well was significantly higher by 4D-CMR flow (P = 0.003 for MPA, < 0.001 for RPA, and 0.002 for LPA). The Bland-Altman plots showed a good agreement between 4D-CMR and 2D-PC flow for the SVI, RF, and PSV across the pulmonary arteries. CONCLUSION: A good agreement existed between the two studied methods regarding pulmonary flow measurements. Because of its major advantage of performing a comprehensive flow assessment in a shorter time, 4D-CMR flow plays an important role in the assessment of patients with complex CHD especially in the pediatric group.

Multi-detector computed tomography in the assessment of tetralogy of Fallot patients: is it a must?

BACKGROUND: Tetralogy of Fallot (TOF) accounts for 10% of all CHD. It classically consists of ventricular septal defect (VSD), aortic overriding, right ventricular outflow tract (RVOT) obstruction, and RV hypertrophy. There are many anatomic variants, associated intracardiac and extracardiac anomalies that must be taken into consideration when imaging and planning the surgical procedure needed. Multi-detector computed tomography (MDCT), with its high spatial and temporal resolution, has a pivotal role in the evaluation of complex anatomical findings in both unrepaired and repaired TOF patients. MAIN BODY: Though MDCT has a limited role in the initial diagnosis of TOF, it is particularly important when there is a question about anatomy of pulmonary arteries (PAs) (whether sizable, hypoplastic, or atretic), presence of major aorto-pulmonary collaterals (MAPCAs) and presence of additional VSDs. Additionally, MDCT is crucial in the diagnosis of different anatomical variants of TOF. TOF patients with absent pulmonary valve classically have hugely dilated PAs which raise an important question about the degree and severity of airways compression. This question can be accurately answered by MDCT. TOF with double-outlet RV (DORV) has variable degrees of aortic override which can be assessed by MDCT. An atrio-ventricular septal defect (AVSD) is seen in about 13% of TOF cases and typically occurs in patients with Down syndrome. MDCT can assess the size and extent of inlet VSD and size of both ventricles (balanced or unbalanced AVSD). Coronary artery anomalies are common and important association. MDCT can identify the presence of a major coronary artery crossing the RVOT, a left anterior descending (LAD) from RCA, or a dual LAD. The clinical importance of these anomalies is its susceptibility to injury during ventriculotomy incision required for TOF repair necessitating changing the usual approach of surgery. Patients with reduced pulmonary blood flow undergo a systemic to pulmonary shunt. MDCT can assess the patency of the shunt, stenotic, or occluded segments. In surgically repaired TOF patients, MDCT can identify the sequalae and long-term complications including residual RVOT obstruction, conduit stenosis, RVOT patch aneurysm, RVH, and aortic root dilatation. CONCLUSION: MDCT is a safe and reliable imaging modality that provides accurate assessment of anatomical variants and associated anomalies of TOF.