Pulmonary regurgitation is a powerful factor influencing QRS duration in patients after surgical repair of tetralogy of Fallot

Repaired Tetralogy of Fallot: Have We Understood the Right Timing of PVR?

Despite many advances in surgical repair during the past few decades, the majority of tetralogy of Fallot patients continue to experience residual hemodynamic and electrophysiological abnormalities. The actual issue, which has yet to be solved, is understanding how this disease evolves in each individual patient and, as a result, who is truly at risk of sudden death, as well as the proper timing of pulmonary valve replacement (PVR). Our responsibility should be to select the most appropriate time for each patient, going above and beyond imaging criteria used up to now to make such a clinically crucial decision. Despite several studies on timing, indications, procedures, and outcomes of PVR, there is still much uncertainty about whether PVR reduces arrhythmia burden or improves survival in these patients and how to appropriately manage this population. This review summarizes the most recent research on the evolution of repaired tetralogy of Fallot (from adolescence onwards) and risk factor variables that may favor or delay PVR.

Biventricular myocardial adaptation in patients with repaired tetralogy of Fallot: Mechanistic insights from magnetic resonance imaging tissue phase mapping

BACKGROUND

The myocardial adaptive mechanism in patients with repaired tetralogy of Fallot (rTOF) is less understood. We aimed to investigate biventricular myocardial adaptive remodeling in rTOF patients.

METHODS

We recruited 32 rTOF patients and 38 age- and sex-matched normal controls. The pulmonary stenosis of rTOF patients was measured using catheterized pressure gradient between right ventricle (RV) and pulmonary artery (PGRVPA). rTOF patients with PGRVPA < 15 mmHg and ≥15 mmHg were classified as low pulmonary stenosis (rTOFlow, n = 19) and high pulmonary stenosis (rTOFhigh, n = 13) subgroups, respectively. Magnetic resonance imaging tissue phase mapping was employed to evaluate the voxelwise biventricular myocardial motion in longitudinal (Vz), radial (Vr), and circumferential (Vφ) directions.

RESULTS

The rTOFlow subgroup presented higher pulmonary regurgitation fraction than rTOFhigh subgroup (p < 0.001). Compared with the normal group, only rTOFlow subgroup presented a decreased RV ejection fraction (RVEF) (p < 0.05). The rTOFlow subgroup showed decreased systolic and diastolic Vz in RV and LV, whereas rTOFhigh subgroup showed such change only in RV. In rTOFlow subgroup, RVEF significantly correlated with RV systolic Vr (r = 0.56, p < 0.05), whereas LVEF correlated with LV systolic Vz (r = 0.51, p = 0.02). Prolonged QRS correlated with RV systolic Vr (r = -0.58, p < 0.01) and LV diastolic Vr (r = 0.81, p < 0.001). No such correlations occurred in rTOFhigh subgroup.

CONCLUSIONS

The avoidance of unfavorable functional interaction in RV and LV in rTOFhigh subgroup suggested that adequate pulmonary stenosis (PGRVPA ≥ 15 mmHg in this sereis) has a protective effect against pulmonary regurgitation.

Electrocardiogram QRS duration and associations with telomere length: A cross-sectional analysis in Australian rural diabetic and non-diabetic population

Prolonged electrocardiogram QRS durations are often present in aging populations. Shorter telomere length is considered a biomarker of cellular aging. Decreased telomere length has been associated with coronary artery risk, and ventricular remodeling. However, the association between telomeres and cardiac conduction abnormalities, such as increased QRS duration are not well understood. A retrospective cross-sectional population was obtained from the CSU Diabetes Screening Research Initiative database where 273 participants had both ECG-derived QRS duration and DNA to permit leukocyte telomere length (LTL) determination. Telomere length was determined using the monochrome multiplex quantitative PCR method to measure mean relative LTL. Resting 12-lead electrocardiograms were obtained from each subject using a Welch Allyn PC-Based ECG system. Relative LTL was moderately negatively associated with QRS duration in type 2 diabetes mellitus (T2DM) patients (R²=0.055), compared to controls (R²=0.010). In general linear models with no adjustments a significant interaction between QRS duration and LTL is observed for a combined population of T2DM and non-diabetics. When we compared T2DM to non-diabetics, we found that T2DM increased the effect size for relative LTL on QRS duration in comparison to controls. Hence, for each 0.1 unit of relative LTL attrition, QRS duration in T2DM patients increased by 3.24ms (95% CI, -63.00 to -1.84), compared to 1.65ms in controls (95% CI, -40.44 to 7.40). In summary we have observed an association between LTL in a rural aging mixed population of T2DM and non-diabetes. We have observed an unadjusted association between QRS duration and LTL in T2DM. We noted that the control group demonstrated no such association. This highlights the complexity of T2DM when exploring disease phenotype-telomere interactions.

Dimensions of the ascending aorta in children and adolescents with repaired Tetralogy of Fallot obtained by cardiac magnetic resonance angiography

Introduction

Dilatation of the ascending aorta is a common finding in Tetralogy of fallot (TOF). We sought to provide aortic dimensions in children and adolescents after corrected TOF obtained by contrast-enhanced cardiac-magnetic-resonance angiography (CE-CMRA) that could serve as reference values.

Materials and methods

We enrolled 101 children and adolescents (56 male) with a median age of 10.9 years. All patients underwent CE-CMRA imaging using a 3-dimensional spoiled gradient-echo-sequence. Aortic diameters were measured at the level of the aortic valve (AV), aortic sinus (AS), sino-tubular junction (STJ) and the ascending aorta (AA) and compared with normal values obtained from literature. Sex-specific aortic dimensions are given as percentile curves as well as z scores. Furthermore CMR volumetric and functional parameters as well as clinical and anamnestic data were analyzed to identify parameters that are associated with aortic dilatation.

Results

Diameters for aortic size for males were 3.6 + 16.6*BSA^0.5 at the AV level, 7.0 + 19.5*BSA^0.5 at the AS level, 7.0 + 14.4*BSA^0.5 at the STJ level and 7.3 + 15.5*BSA^0.5 at the AA level. Diameters for females were 5.8 + 14.1*BSA^0.5 at the AV level, 7.2 + 17.6*BSA^0.5 at the AS level, 5.2 + 15.4*BSA^0.5 at the STJ level and 2.0 + 17.8*BSA^0.5 at the AA level. All diameters in TOF patients were larger compared with normal values. The postoperative interval and age at examination were the only parameters associated with aortic size at all measured levels.

Conclusion

We provide CE-CMRA data of aortic dimensions in children and adolescents after correction of TOF. Our data might be useful for an estimation of the “normal” aortic size in this patient cohort and can serve as a basis for future longitudinal studies adding prognostic data.

Semi-automatic vortex extraction in 4D PC-MRI cardiac blood flow data using line predicates

Cardiovascular diseases (CVD) are the leading cause of death worldwide. Their initiation and evolution depends strongly on the blood flow characteristics. In recent years, advances in 4D PC-MRI acquisition enable reliable and time-resolved 3D flow measuring, which allows a qualitative and quantitative analysis of the patient-specific hemodynamics. Currently, medical researchers investigate the relation between characteristic flow patterns like vortices and different pathologies. The manual extraction and evaluation is tedious and requires expert knowledge. Standardized, (semi-)automatic and reliable techniques are necessary to make the analysis of 4D PC-MRI applicable for the clinical routine. In this work, we present an approach for the extraction of vortex flow in the aorta and pulmonary artery incorporating line predicates. We provide an extensive comparison of existent vortex extraction methods to determine the most suitable vortex criterion for cardiac blood flow and apply our approach to ten datasets with different pathologies like coarctations, Tetralogy of Fallot and aneurysms. For two cases we provide a detailed discussion how our results are capable to complement existent diagnosis information. To ensure real-time feedback for the domain experts we implement our method completely on the GPU.

The systemic right ventricle in congenitally corrected transposition of the great arteries is different from the right ventricle in dextro-transposition after atrial switch: a cardiac magnetic resonance study

BACKGROUND

Patients with a congenitally corrected transposition of the great arteries show an increasing incidence of cardiac failure with age. In other systemic right ventricles, such as in dextro-transposition after atrial switch, excessive hypertrophy is a potential risk factor for impaired systolic function. In this trial, we sought to compare systemic function and volumes between patients with congenitally corrected transposition and those with dextro-transposition after atrial switch by using cardiac magnetic resonance imaging.

METHODS AND RESULTS

A total of 19 patients (nine male) with congenitally corrected transposition and 31 patients (21 male) with dextro-transposition after atrial switch were studied using a 1.5-Tesla scanner. Cine steady-state free-precession sequences in standard orientations were acquired for volumetric and functional imaging. Patient parameters were compared with those of a group of 25 healthy volunteers. Although patients with congenitally corrected transposition were older, they presented with higher right ventricular ejection fractions (p = 0.04) compared with patients with dextro-transposition. Patients with congenitally corrected transposition showed a weak negative correlation between age at examination and systemic ejection fraction (r = −0.18, p = 0.04) but no correlation between right ventricular myocardial mass index and ejection fraction. There was no significant difference in the right ventricular end-diastolic volumes between both patient groups.

CONCLUSION

Although patients with congenitally corrected transposition had a longer pressure load of the systemic right ventricle, ventricular function was better compared with that in patients with dextro-transposition after atrial switch. The results suggest that the systemic ventricles might have partly different physiologies. One difference could be the post-operative situation after atrial switch, which results in impaired atrial contribution to ventricular filling.

Numerical study for blood flow in pulmonary arteries after repair of tetralogy of Fallot

Pulmonary regurgitation (PR) is a common phenomenon in pulmonary arteries in patients after repair of tetralogy of Fallot (TOF). The regurgitation fraction of left pulmonary artery (LPA) is usually greater than right pulmonary artery (RPA) according to clinic data. It may be related to blood flow in pulmonary arteries. Therefore, understanding hemodynamics in pulmonary arteries helps to comprehend the reason. The aim of this study is to use 3D reconstructed pulmonary artery models from magnetic resonance imaging (MRI) and to use numerical approaches for simulation of flow variations in pulmonary arteries after repair of TOF. From the numerical results, the blood flow is influenced by the bifurcation angles and geometry of pulmonary artery. The regurgitation happens first in LPA after repair of TOF due to the small angle between LPA and main pulmonary artery (MPA). The recirculation region which obstructs forward blood flow to the left lung is found in LPA during acceleration of systole. We also analyze the pressure distribution; the extreme pressure variations are in dilation area of MPA. Numerical data including regurgitation in MPA, LPA, and RPA are compared with phase contrast MR measured data. Good agreements are found between numerical results and measured data.

Right ventricular hypertrophy after atrial switch operation: normal adaptation process or risk factor? A cardiac magnetic resonance study

Background

Systemic right ventricle (RV) hypertrophy and impaired function occur after atrial switch for dextro-transposition of the great arteries (d-TGA). Echocardiography is limited in its ability to assess the RV. We sought to evaluate systemic RV myocardial-mass index (MMI) and function after atrial switch and to analyse the role of hypertrophy for ventricular function with special consideration of the interventricular septal (IVS) movement.

Methods

Thirty-seven consecutive patients (median age 22.9 years) after atrial switch were studied using cardiac magnetic resonance imaging (1.5T Intera, Philips) with a dedicated 5-channel phased-array surface cardiac coil. Cine steady-state free-precession sequences were acquired to obtain myocardial masses and function. The systolic movement of the IVS was defined as positive when moving towards the centroid of the RV and was defined as non-positive otherwise. Patient parameters were compared to controls.

Results

The systemic RVs were significantly larger (p < 0.001) than the left ventricles of the control group, systolic function was significantly impaired (p < 0.001) and MMI including the IVS was comparable (p = n.s.). RV-MMI excluding the IVS and RV ejection fraction (EF) demonstrated a quadratic correlation (r = 0.6, p < 0.001), meaning that patients with RV-MMI ≤29 g/m² and >68 g/m² had a reduced level of systolic function. Positive septal movement improved RV function compared with non-positive septal movement (p = 0.024).

Conclusions

There seems to be a range of beneficial RV hypertrophy after atrial switch in which a sufficient RV-EF can be expected. A positive septal movement, probably the result of hypertrophic septal RV fibres, improves RV function and might be regarded as a beneficial contraction pattern.

Real-time transesophageal three-dimensional echocardiography for guidance of percutaneous cardiac interventions: first experience

Recently, a new generation of transesophageal echocardiography (TEE) probes with a novel matrix array technique was introduced, allowing three-dimensional (3D) presentation of cardiac structures in real-time. This article aims to describe our first experiences with this new technique in the guidance of percutaneous cardiac interventions in the catheter laboratory. We used a matrix array 3D TEE probe connected to a 3D-capable echocardiographic system. The 3D TEE system provides exact imaging of the pathomorphology of cardiac structures as well as intracardiac catheters and devices in real-time. We applied this innovative technique to monitor percutaneous cardiac interventions in the catheter laboratory, such as atrial septal defect (ASD) or patent foramen ovale (PFO) closures, revalving procedures such as percutaneous transvenous mitral valve annuloplasty (PTMA), aortic valve replacements, and electrophysiological procedures. Our findings demonstrate that real-time 3D TEE provides a novel imaging technique to guide interventions in the catheter laboratory, providing fast and complete information about the underlying pathomorphology, improving spatial orientation, and additionally monitoring online the procedure without loss of image quality. These benefits may accelerate the learning curve and improve confidence of the interventional cardiologist in order to increase safety, accuracy, and efficacy of interventional cardiac procedures.

Evaluation of postoperative pulmonary regurgitation after surgical repair of tetralogy of Fallot: comparison between Doppler echocardiography and MR velocity mapping

BACKGROUND

Pulmonary regurgitation is a common finding in patients after correction of tetralogy of Fallot (TOF). Right ventricular impairment and even ventricular arrhythmia have been ascribed to pulmonary valve insufficiency (PI), which is therefore an important issue in follow-up examinations.

OBJECTIVE

To compare PI measured by echocardiography (ECHO) with data provided by cardiac MRI (CMR).

MATERIALS AND METHODS

We studied 54 selected patients (18 female; median age 14.0 years, range 3.8-53.4 years) after surgical correction of TOF. To quantify pulmonary regurgitant fraction (PRF) by CMR, flow velocity mapping was performed. On Doppler ECHO, length, width and localization of regurgitant flow was measured. The severity of PI was categorized as mild, moderate or severe and compared to the data obtained by CMR.

RESULTS

On CMR the mean PRF was 29.2 +/- 13.4%. Patients with a transannular patch had a significantly higher PRF (39.9 +/- 11.6%) than patients with an intact annular ring (23.6 +/- 11.4%). Differentiation by Doppler ECHO between the categories mild, moderate and severe PI was confirmed by significant differences in PRF measured by CMR (mild vs. moderate P < 0.04; moderate vs. severe P < 0.014; mild vs. severe P < 0.001). Furthermore, PRF correlated with right ventricular end diastolic volume index (r = 0.45, P < 0.01) and right ventricular end systolic volume index (r = 0.39, P < 0.01).

CONCLUSION

Doppler ECHO can estimate the severity of PI after repair of TOF with acceptable results compared to CMR flow measurement. In univariate analysis there is only a weak influence of PRF on right ventricular volume.