Changes in blood volume shunting in patients with atrial septal defects: assessment of heart function with cardiovascular magnetic resonance during dobutamine stress

Clinical impact of novel cardiovascular magnetic resonance technology on patients with congenital heart disease: a scientific statement of the Association for European Pediatric and Congenital Cardiology and the European Association of Cardiovascular Imaging of the European Society of Cardiology

Cardiovascular magnetic resonance (CMR) imaging is recommended in patients with congenital heart disease (CHD) in clinical practice guidelines as the imaging standard for a large variety of diseases. As CMR is evolving, novel techniques are becoming available. Some of them are already used clinically, whereas others still need further evaluation. In this statement, the authors give an overview of relevant new CMR techniques for the assessment of CHD. Studies with reference values for these new techniques are listed in the Supplementary data online, supplement.

Adults with small, unrepaired atrial septal defects have reduced cardiac index during exercise

OBJECTIVES

Small, unrepaired atrial septal defects are considered a benign lesion with good prognosis. Recently, clinical and register-based studies discovered increased long-term mortality and morbidity. The nature of these findings is not fully understood. Therefore, MRI was performed to evaluate cardiac function at rest and during exercise.

METHODS

Adults with open or spontaneously closed atrial septal defects and healthy, matched controls underwent MRI for evaluation of cardiac chamber volume. Quantitative flow scans measured blood flow in the ascending aorta and the proximal pulmonary artery at rest and during increasing supine exercise.

RESULTS

In total, 15 open defects (39 ± 11 years) and 15 matched controls (38 ± 12 years) were included, along with 20 spontaneously closed (36 ± 13 years) and 20 controls (36 ± 11 years). Cardiac chamber volumes and flow measurements at rest were comparable between groups, as were heart rates and workloads during exercise. At maximal exercise, open defects reached 31% lower cardiac index and had 38% higher retrograde flow in the pulmonary artery than their controls, p < 0.01. Shunt ratio remained unchanged during exercise, 1.2 ± 0.2. Closed defects reached 18% lower cardiac index, p = 0.02, with comparable pulmonary retrograde flow. Maximal cardiac index was inversely correlated with increasing age for patients only.

CONCLUSION

Adults with a small, open or spontaneously closed atrial septal defects exhibit markedly lower exercise capacity compared with healthy peers. Moreover, open defects exhibit higher retrograde flows with increasing exercise. Finally, increasing age is related to poorer results in patients but not healthy controls. Longitudinal studies are necessary in order to determine potential accelerated worsening of physical capacity along with age-related changes in patients.

Deep learning can yield clinically useful right ventricular segmentations faster than fully manual analysis

Right ventricular (RV) volumes are commonly obtained through time-consuming manual delineations of cardiac magnetic resonance (CMR) images. Deep learning-based methods can generate RV delineations, but few studies have assessed their ability to accelerate clinical practice. Therefore, we aimed to develop a clinical pipeline for deep learning-based RV delineations and validate its ability to reduce the manual delineation time. Quality-controlled delineations in short-axis CMR scans from 1114 subjects were used for development. Time reduction was assessed by two observers using 50 additional clinical scans. Automated delineations were subjectively rated as (A) sufficient for clinical use, or as needing (B) minor or (C) major corrections. Times were measured for manual corrections of delineations rated as B or C, and for fully manual delineations on all 50 scans. Fifty-eight % of automated delineations were rated as A, 42% as B, and none as C. The average time was 6 min for a fully manual delineation, 2 s for an automated delineation, and 2 min for a minor correction, yielding a time reduction of 87%. The deep learning-based pipeline could substantially reduce the time needed to manually obtain clinically applicable delineations, indicating ability to yield right ventricular assessments faster than fully manual analysis in clinical practice. However, these results may not generalize to clinics using other RV delineation guidelines.

Cardiopulmonary haemodynamics after sieve-shaped atrial septal defect repair: a multicenter study

OBJECTIVE

The study aimed to collect case data on cardiopulmonary bypass (CPB) sieve-shaped (S-S) and non-sieve-shaped (N-S-S) atrial septal defects (ASDs).

METHODS

We analysed and summarized the postoperative blood flow in the cardiopulmonary system. We retrospectively collected 86 patients who underwent CPB S-S and N-S-S ASD repair. The data collected included sex, age, CPB time, ASD area, percentage change in ventricular value (PVV) (preoperative/postoperative), left ventricular wall thickness, ejection fraction (EF) (preoperative/postoperative), fluid inflow value, pulmonary arterial pressure/pulmonary venous pressure, percentage change in total lung resistance (PTLR) (preoperative/postoperative) for statistical analysis and comparison.

RESULTS

There were 86 eligible patients in this study, 37 and 49 of whom had S-S and N-S-S ASDs, respectively. The PVV, PTLR, and pulmonary arterial pressure/pulmonary venous pressure (postoperative) were significantly different between the S-S and N-S-S groups. The mean PTLR in the S-S and N-S-S groups was 0.78±0.24 and 0.62±0.28, respectively. The mean PVV in the S-S group was 11.53±7.63, and that in the N-S-S group was 16.47±9.71. Multivariate analysis revealed PVV (OR, 0.143; 95% CI, 0.026-0.790; P=0.026), PTLR (OR, 0.156; 95% CI, 0.049-0.500; P=0.002), and pulmonary arterial pressure/pulmonary venous pressure (postoperative) (OR, 9.014; 95% CI, 2.480-32.755; P=0.001) as significant factors. The rate of pulmonary infection absence postoperatively in the S-S group was 76.52%, and that in the N-S-S group was 42.75%.

CONCLUSION

Due to the differences in heart structure between the S-S and N-S-S groups, the haemodynamic index (PVV and PTLR, postoperative pulmonary arterial pressure/pulmonary venous pressure) changes after S-S ASD repair were less than those after N-S-S ASD repair, so the postoperative pulmonary infection rate was higher after N-S-S ASD repair. The pulmonary infection rate was low after S-S ASD repair, and drugs should be reasonably administered to prevent infection.

Impact of Right Ventricular Dilatation in Patients with Atrial Septal Defect

Objective

The aim of this study was to examine the relationship between right ventricular (RV) volume and exercise capacity in adult patients with atrial septal defect (ASD) and to determine the degree of RV dilatation for transcatheter ASD closure.

Background

RV dilatation is an indication of transcatheter ASD closure; however, few studies have reported the clinical significance of RV dilatation.

Methods

We enrolled 82 consecutive patients (mean age, 49 ± 18 years; female, 68%) who underwent cardiac magnetic resonance imaging and symptom-limited cardiopulmonary exercise test before ASD closure. The relationship between RV volume and peak oxygen uptake (VO₂) was evaluated.

Results

The mean RV end-diastolic volume index was 108 ± 27 ml/m² (range, 46 to 180 ml/m²). The mean peak VO₂ was 24 ± 7 ml/min/kg (range, 14 to 48 ml/min/kg), and the mean predicted peak VO₂ was 90 ± 23%. There were significant negative relationships of RV end-diastolic volume index with peak VO₂ (r = -0.28, p < 0.01) and predicted peak VO₂ (r = -0.29, p < 0.01). The cutoff value of RV end-diastolic volume index <80% of predicted peak VO₂ was 120 ml/m², with the sensitivity of 49% and the specificity of 89%.

Conclusions

There was a relationship between RV dilatation and exercise capacity in adult patients with ASD. RV end-diastolic volume index ≥120 ml/m² was related to the reduction in peak VO₂. This criterion of RV dilatation may be valuable for the indication of transcatheter ASD closure.

A new vessel segmentation algorithm for robust blood flow quantification from two-dimensional phase-contrast magnetic resonance images

Blood flow measurements in the ascending aorta and pulmonary artery from phase-contrast magnetic resonance images require accurate time-resolved vessel segmentation over the cardiac cycle. Current semi-automatic segmentation methods often involve time-consuming manual correction, relying on user experience for accurate results. The purpose of this study was to develop a semi-automatic vessel segmentation algorithm with shape constraints based on manual vessel delineations for robust segmentation of the ascending aorta and pulmonary artery, to evaluate the proposed method in healthy volunteers and patients with heart failure and congenital heart disease, to validate the method in a pulsatile flow phantom experiment, and to make the method freely available for research purposes. Algorithm shape constraints were extracted from manual reference delineations of the ascending aorta (n = 20) and pulmonary artery (n = 20) and were included in a semi-automatic segmentation method only requiring manual delineation in one image. Bias and variability (bias ± SD) for flow volume of the proposed algorithm versus manual reference delineations were 0·0 ± 1·9 ml in the ascending aorta (n = 151; seven healthy volunteers; 144 heart failure patients) and -1·7 ± 2·9 ml in the pulmonary artery (n = 40; 25 healthy volunteers; 15 patients with atrial septal defect). Interobserver bias and variability were lower (P = 0·008) for the proposed semi-automatic method (-0·1 ± 0·9 ml) compared to manual reference delineations (1·5 ± 5·1 ml). Phantom validation showed good agreement between the proposed method and timer-and-beaker flow volumes (0·4 ± 2·7 ml). In conclusion, the proposed semi-automatic vessel segmentation algorithm can be used for efficient analysis of flow and shunt volumes in the aorta and pulmonary artery.

Aerobic capacity in adolescence is associated with time to intervention in adult men with atrial septal defects

BACKGROUND

Atrial septal defect (ASD) is a congenital heart lesion that often remains undiagnosed until adulthood. The reasons for this may be multifactorial. It is, however, known that closure of a hemodynamically significant ASD improves exercise capacity. This study aimed to explore whether the aerobic capacity in late adolescence is associated with time to diagnosis and intervention in adult men with late diagnosis of an atrial shunt.

METHODS

The Swedish Military Conscription Service Register contains data on exercise tests performed in late adolescence. By linking these data with the National Patient Register, 254 men with a later intervention for an ASD were identified.

RESULTS

Interventions were performed at a mean of 26.5 ± 7.9 years after the initial exercise tests. The mean absolute workload among those with a later diagnosed ASD was similar to those without a later diagnosed ASD (274 ± 51 W vs. 276 ± 52 W, p = 0.49). Men with a higher exercise capacity (≥1 SD) had their intervention earlier (21.9 ± 8.6 years vs. 27.5 ± 7.4 years, p < 0.001).

CONCLUSIONS

The aerobic exercise capacity was similar in adolescent men with later interventions for ASD compared to the reference population. Furthermore, those with high exercise capacity appeared to be diagnosed earlier. Thus, low exercise capacity may not be a feature of ASD during adolescence, but rather develop later in life as a natural progression of the disease.

The year 2017 in the European Heart Journal-Cardiovascular Imaging: Part II

European Heart Journal - Cardiovascular Imaging was launched in 2012 as a multimodality cardiovascular imaging journal. It has gained an impressive impact factor of 8.366 during its first 5 years and is now established as one of the top 10 cardiovascular journals and has become the most important cardiovascular imaging journal in Europe. The most important studies from 2017 will be highlighted in two reports. Part I of the review will focus on studies about myocardial function and risk prediction, myocardial ischaemia, and emerging techniques in cardiovascular imaging, while Part II will focus on valvular heart disease, heart failure, cardiomyopathies, and congenital heart disease.

Atrial septal defect and exercise capacity: value of cardio-pulmonary exercise test in assessment and follow-up

Nearly four decades ago, the World Health Organization stated that functional capacity explorations best reflected the impact of a chronic disease on quality of life. Today, cardio-pulmonary exercise test (CPET) is recommended in the follow-up of patients with congenital heart diseases (CHDs). Indeed, the maximum oxygen uptake (VO_2max) and the ventilatory efficiency (VE/VCO₂ slope) correlate with both the prognosis and the quality of life in this population. Atrial septal defects (ASDs) represent the second most frequent CHD and are usually considered as simple CHDs. However, the exercise capacity of ASD patients may be impaired. Therefore, the CPET provides important information in assessment and follow-up of patients with ASDs, for both children and adults. Exercise capacity of patients with unrepaired ASDs depends on the importance of the shunt, the right ventricular (RV) function and volume overload, the level of pulmonary arterial pressure, and the occurrence of arrhythmias. For repaired ASDs, exercise capacity also depends on the delay before closure and the type of procedure (catheter or surgery). In most cases, the exercise capacity is nearly normal and CPET contributes to promote sports participation. In addition, a regular CPET follow-up is necessary to evaluate the occurrence, severity and physiological mechanisms of comorbidities, i.e., heart failure, pulmonary hypertension and arrhythmia. Furthermore, CPET follow-up in patients with ASDs may detect early onset of muscular deconditioning, for which cardiac rehabilitation may be considered.

Alterations in ventricular pumping in patients with atrial septal defect at rest, during dobutamine stress and after defect closure

BACKGROUND

Regional ventricular pumping mechanisms in patients with volume-loaded right ventricles (RV) are altered, but the cause is unknown. The aim was to determine whether these changes in ventricular pumping mechanisms are influenced by the RV dilatation itself or the aetiology behind it.

METHODS

Seventeen patients with atrial septal defects (ASD) and 10 healthy controls underwent cardiovascular magnetic resonance (CMR) at rest and during dobutamine/atropine stress. Sixteen patients underwent transcutaneous ASD closure. Follow-up CMR at rest was performed the following day. Thirty patients with RV overload due to pulmonary regurgitation (PR) underwent CMR at rest. Cine images were used to measure left ventricular (LV) and RV volumes as well as septal, longitudinal and lateral contributions to LV and RV stroke volume (SV).

RESULTS

At rest, septal contribution to LVSV was lower in ASD patients than controls (-1% versus 7%, P<0·05), but there was no difference in longitudinal or lateral contribution to SV. Patients with PR had lower longitudinal contribution to RV with increased lateral and septal contribution. During dobutamine stress, longitudinal contribution to LV and RVSV decreased and lateral contribution increased for ASD patients and controls. The day after ASD closure, septal contribution to LVSV was 6%, longitudinal contribution had increased for RVSV (P<0·05) and decreased for LVSV (P<0·01).

CONCLUSION

Pumping mechanisms in patients with RV volume overload depend on the aetiology for the RV dilation and not the size of the RV.

Left ventricular dispersion as a parameter for augmented left ventricular stroke volume in patients with atrial septal defect following transcatheter closure

OBJECTIVES

The closure of atrial septal defect (ASD) results in normalized left ventricular (LV) and right ventricular (RV) geometry, and can increase LV stroke volume (LVSV), but the parameters associated with this increase after the closure of ASD remain uncertain.

METHODS

Seventy ASD patients, who underwent transcatheter closure, were studied. Their mean age was 57.80 ± 16.88 years, 42 (60%) were female, and LV ejection fraction (LVEF) was 66.76% ± 7.91% (all ≥55%). Transthoracic echocardiography was performed before and 3 months after the procedure. Global longitudinal strain (GLS) was determined as the average peak speckle tracking strain of 18 segments from the 3 standard apical views, LV dispersion was defined as standard deviation of time-to-peak strain from the same views, and RV systolic function was calculated by averaging the 3-regional peak speckle tracking longitudinal strains from the RV free wall. A significant relative increase in LVSV between before and 3 months after the closure was defined as ∆LVSV ≥15%. Twenty age-, gender-, and LVEF-matched controls served as the control group.

RESULTS

Global longitudinal strain (GLS) and RV free wall strain were similar for ASD patients and controls, but LV dispersion in ASD patients was significantly larger. Global longitudinal strain (GLS) remained unchanged after transcatheter closure, whereas RV free wall strain and LV dispersion decreased significantly. An important finding of the multivariate logistic regression analysis showed that ∆LV dispersion was the only independent determinant of increased LVSV after the closure (OR 1.023; 95% CI 1.001-1.046; P < .01).

CONCLUSIONS

The assessment of LV dispersion may well have clinical implications for better management of ASD patients after transcatheter closure.