Tobias Rutz

Compressed sensing single-breath-hold CMR for fast quantification of LV function, volumes, and mass.

OBJECTIVES The purpose of this study was to compare a novel compressed sensing (CS)-based single-breath-hold multislice magnetic resonance cine technique with the standard multi-breath-hold technique for the assessment of left ventricular (LV) volumes and function. BACKGROUND Cardiac magnetic resonance is generally accepted as the gold standard for LV volume and function assessment. LV function is 1 of the most important cardiac parameters for diagnosis and the monitoring of treatment effects. Recently, CS techniques have emerged as a means to accelerate data acquisition. METHODS The prototype CS cine sequence acquires 3 long-axis and 4 short-axis cine loops in 1 single breath-hold (temporal/spatial resolution: 30 ms/1.5 × 1.5 mm(2); acceleration factor 11.0) to measure left ventricular ejection fraction (LVEF(CS)) as well as LV volumes and LV mass using LV model-based 4D software. For comparison, a conventional stack of multi-breath-hold cine images was acquired (temporal/spatial resolution 40 ms/1.2 × 1.6 mm(2)). As a reference for the left ventricular stroke volume (LVSV), aortic flow was measured by phase-contrast acquisition. RESULTS In 94% of the 33 participants (12 volunteers: mean age 33 ± 7 years; 21 patients: mean age 63 ± 13 years with different LV pathologies), the image quality of the CS acquisitions was excellent. LVEF(CS) and LVEF(standard) were similar (48.5 ± 15.9% vs. 49.8 ± 15.8%; p = 0.11; r = 0.96; slope 0.97; p < 0.00001). Agreement of LVSV(CS) with aortic flow was superior to that of LVSV(standard) (overestimation vs. aortic flow: 5.6 ± 6.5 ml vs. 16.2 ± 11.7 ml, respectively; p = 0.012) with less variability (r = 0.91; p < 0.00001 for the CS technique vs. r = 0.71; p < 0.01 for the standard technique). The intraobserver and interobserver agreement for all CS parameters was good (slopes 0.93 to 1.06; r = 0.90 to 0.99). CONCLUSIONS The results demonstrated the feasibility of applying the CS strategy to evaluate LV function and volumes with high accuracy in patients. The single-breath-hold CS strategy has the potential to replace the multi-breath-hold standard cardiac magnetic resonance technique.

Right ventricular absolute myocardial blood flow in complex congenital heart disease

Objective A consequence in patients with d-transposition of the great arteries (d-TGA) and tetralogy of Fallot (TOF) is right ventricular hypertrophy (RVH) and right ventricular failure. Myocardial contrast echocardiography (MCE) permits the determination of the myocardial microvascular density reflected by the relative myocardial blood volume (rBV; ml/ml). This study was conducted to elucidate the relationship between RVH and myocardial microvascular changes by quantitative MCE in patients with d-TGA and TOF. Methods Three groups of individuals were included in the study: 22 patients with d-TGA, 18 patients with TOF and 22 healthy individuals (controls). MCE was performed at rest and during adenosine-induced hyperaemia. rBV and myocardial blood flow (MBF; ml/min per gram) were derived from steady state and refill sequences of ultrasound contrast agent. Results Hyperaemic septal rBV differed significantly between the groups and was highest in controls: d-TGA 0.141±0.060 ml/ml, TOF 0.134±0.080 ml/ml, controls 0.189±0.074 ml/ml, p=0.005. Myocardial blood flow reserve (MBFR), that is the ratio of hyperaemic to baseline MBF, differed significantly between the groups and was lowest in d-TGA (2.68±1.13) versus TOF (3.37±1.57) and controls (4.22±1.17, p=0.001). Hyperaemic septal rBV, MBF and MBFR showed a significant correlation with right ventricular systolic function as determined by tricuspid annular plane systolic excursion. Conclusions Right ventricular myocardial microvascular density of the septal wall in d-TGA and TOF patients with RVH due to pressure and/or volume overload is reduced. This appears to be related to a reduced myocardial perfusion reserve and impaired right ventricular systolic function.

Distensibility and Diameter of Ascending Aorta Assessed by Cardiac Magnetic Resonance Imaging in Adults With Tetralogy of Fallot or Complete Transposition

Structural abnormalities of the medial aorta have been described for conotruncal defects (e.g., tetralogy of Fallot [TOF] and complete transposition of the great arteries (dextrotransposition [d]-TGA). In TOF, progressive aortic dilation is a frequent finding. In patients with d-TGA with an atrial switch, this problem is less often described. The aim of the present study was to compare the extent of dilative aortopathy and aortic distensibility in adults with an atrial switch procedure (n = 39) to that in adults with repaired TOF (n = 39) and controls (n = 39), using cardiac magnetic resonance imaging. The groups were matched for age and gender. Diameters of the aorta indexed to the body surface area were significantly increased in the patients with d-TGA and TOF compared to that of the controls at the aortic sinus up to the level of the right pulmonary artery. On multivariate testing, the diagnosis of a conotruncal defect (β = 0.260; p = 0.003) and aortic regurgitant fraction (β = 0.405; p <0.001) were independent predictors of an increased aortic sinus diameter. Ascending aorta distensibility was significantly reduced in those with d-TGA and TOF compared to controls: 3.6 (interquartile range 1.5 to 4.4) versus 2.8 (interquartile range 2.0 to 3.7) versus 5.5 (interquartile range 4.8 to 6.9) ×10(-3) mm Hg(-1) (p <0.001). The independent predictors of ascending aorta distensibility were the diagnosis of a conotruncal defect (p <0.001) and age (p = 0.028). In conclusion, intrinsic aortopathy, manifested as increased ascending aortic diameters and reduced ascending aortic distensibility, is not only evident in adults with TOF, but also in adults with d-TGA and an atrial switch procedure. Long-term follow-up is needed to monitor the aortic size in both patient groups.

Quantitative myocardial contrast echocardiography: a new method for the non-invasive detection of chronic heart transplant rejection

BACKGROUND Chronic heart transplant rejection, i.e. cardiac allograft vasculopathy (CAV) is a major adverse prognostic factor after heart transplantation (HTx). This study tested the hypothesis that the relative myocardial blood volume (rBV) as quantified by myocardial contrast echocardiography accurately detects severe CAV as defined by coronary intravascular ultrasound (IVUS). METHODS AND RESULTS Forty-five HTx patients underwent a total of 50 quantitative IVUS measurements for intima thickness assessment (>1 mm = severe CAV; the reference method). Simultaneously, the two factors constituting myocardial perfusion (mL/min/g) were obtained by transthoracic contrast echocardiography at rest: rBV (the test method), a measure of microvascular density (mL/mL), and its exchange rate β (1/s; a measure of coronary conductance) after mechanical contrast bubble disruption.Sixty-nine per cent (31 of 45) of the HTx patients showed severe CAV. rBV at rest was equal to 0.17 ± 0.05 in the group without severe CAV, and it was equal to 0.12 ± 0.07 in the group with severe CAV (P = 0.0157). Conversely, β amounted to 6.4 ± 4.5 in the former and to 10.3 ± 6.2 in the latter group (P = 0.0410), thus, maintaining normal resting myocardial perfusion at 1 mL/min/g. IVUS determined intima thickness correlated significantly and inversely with rBV at rest. An rBV value at rest <0.14 accurately detected severe CAV (intima thickness >1 mm): area under the receiver operating characteristics curve = 0.844, P = 0.004, sensitivity = 0.90, specificity = 0.75. CONCLUSION Severe CAV can be detected using the non-invasive method of quantitative myocardial contrast echocardiography. rBV at rest amounting to <14% of the surrounding tissue accurately detects coronary intima thickness >1 mm as determined invasively by IVUS. CLINICAL TRIAL NUMBER NCT00414895.

Comparison of MR flow quantification in peripheral and main pulmonary arteries in patients after right ventricular outflow tract surgery: A retrospective study: MR Flow Measurements in RVOT Pathologies

To compare the quantification of pulmonary stroke volume (SV) by phase contrast magnetic resonance (PC‐MR) in the main pulmonary artery (MPA) to the sum of SVs in both peripheral pulmonary arteries (PPA) in different right ventricular (RV) outflow pathologies.

Effect of phosphodiesterase-5 inhibition with Tadalafil on SystEmic Right VEntricular size and function – A multi-center, double-blind, randomized, placebo-controlled clinical trial – SERVE trial - Rational and design

BACKGROUND Patients with a systemic right ventricle (RV) have a compromised late outcome caused by ventricular dysfunction. Standard medical heart failure therapy has not been shown to improve RV function and survival in these patients. Phosphodiesterase (PDE)-5 inhibition increases contractility in experimental models of RV hypertrophy, but not in the normal RV. In clinical practice, the effects of PDE-5 inhibition on systemic RV function and exercise capacity in adults with a systemic RV have not been tested. METHODS The SERVE protocol is a double-blind, randomized placebo-controlled multicenter superiority trial to study the effect of PDE-5 inhibition with Tadalafil on RV volumes and function in patients with either D-transposition of the great arteries repaired with an atrial switch procedure or with congenitally corrected transposition of the great arteries. Tadalafil 20mg or placebo will be given over a study period of 3years. The primary endpoint is the change in mean end-systolic RV volumes from baseline to study end at 3years of follow-up (or at the time of permanent discontinuation of the randomized treatment if stopped before 3- years of follow-up), and will be measured by cardiovascular magnetic resonance imaging (CMR) or by cardiac computed tomography in patients with contraindications for CMR. Secondary endpoints are changes in RV ejection fraction, VO2max and NT-proBNP. CONCLUSION The objective of this study is to assess the effect of PDE-5 inhibition with Tadalafil on RV size and function, exercise capacity and neurohumoral activation in adults with a systemic RV over a 3-year follow-up period.

Patterns of incidence rates of cardiac complications in patients with congenital heart disease

BACKGROUND This study aimed to evaluate age at the first onset of cardiac complications and variation of frequency of complications between different congenital heart defects. METHODS The analysis included participants of the Swiss Adult Congenital Heart Disease Registry (SACHER). For this study, cardiac complications up to the time of inclusion in SACHER were analysed. Complications included atrial fibrillation, atrial flutter, supraventricular tachycardia, ventricular tachycardia, complete heart block, heart failure, stroke, endocarditis, myocardial infarction, and pulmonary hypertension. Incidence rates (IR; incidence rate per 1000 patient-years) for different age categories and diagnosis groups were analysed. RESULTS Of 2731 patients (55% male, mean age 34 ± 14 years, 92,349 patient-years), a total of 767 (28%) had experienced at least 1 cardiac complication. The majority of complications (550; 72%) occurred in adulthood (> 18 years). Apart from perioperative stroke (IR: 1.77 in age group ≤ 4 years) and complete heart block (IR: 2.36 in age group ≤ 4 years), IR were much lower in childhood (IR < 1 for all complications between 5 and 17 years). Incidence of cardiac complications increased during adult life with highest IR for atrial fibrillation and atrial flutter in the age group ≥ 50 years (IR: 17.6 and 9.7, respectively). There were important variations of the distribution of complications among different diagnosis groups. CONCLUSIONS Cardiac complications are frequent in congenital heart disease. Apart from perioperative stroke and complete heart block, IR are low in childhood but the incidence increases during adult life. These data underscore the need of lifelong follow-up and may help for better allocation of resources maintaining follow-up.

Swiss Adult Congenital HEart disease Registry (SACHER) - rationale, design and first results.

BACKGROUND In 2013, a prospective registry for adults with congenital heart disease (CHD) was established in Switzerland, providing detailed data on disease characteristics and outcomes: Swiss Adult Congenital HEart disease Registry (SACHER). Its aim is to improve the knowledge base of outcomes in adults with CHD. The registry design and baseline patient characteristics are reported. METHODS All patients with structural congenital heart defects or hereditary aortopathies, followed-up at dedicated adult CHD clinics, are asked to participate in SACHER. Data of participants are pseudonymised and collected in an electronic, web-based, database (secuTrial®). Collected data include detailed diagnosis, type of repair procedures, previous complications and adverse outcomes during follow-up. RESULTS From May 2014 to December 2016, 2836 patients (54% male, mean age 34 ± 14 years), with a wide variety of congenital heart lesions, have been enrolled into SACHER. Most prevalent were valve lesions (25%), followed by shunt lesions (22%), cyanotic and other complex congenital heart disease (16%), diseases affecting the right heart, i.e., tetralogy of Fallot or Ebstein anomaly (15%), and diseases of the left ventricular outflow tract (13%); 337 patients (12%) had concomitant congenital syndromes. The majority had undergone previous repair procedures (71%), 47% of those had one or more reinterventions. CONCLUSION SACHER collects multicentre data on adults with CHD. Its structure enables prospective data analysis to assess detailed, lesion-specific outcomes with the aim to finally improve long-term outcomes.

Border sharpness of scar tissue after myocardial infarction as determined by self-navigated free-breathing isotropic 3D whole-heart inversion recovery magnetic resonance

Background The border zone of myocardial scar after myocardial infarction (MI) plays an important role for arrhythmia formation. For this reason, high-resolution 3D information of scar tissue for planning of electrophysiological interventions after MI is highly desirable. This study evaluates sharpness of the borders (SB) of scar after MI by a self-navigated isotropic 3D free-breathing wholeheart magnetic resonance with inversion recovery (3DSN-IR) in comparison to a standard 2D inversion recovery sequence.

Whole heart free breathing phase sensitive inversion recovery MRI integrated with iterative self navigation for 100% scan efficiency; a first patient study

Background Phase Sensitive Inversion Recovery (PSIR) [1] allows for the visualization of myocardial scars using late gadolinium enhancement (LGE), ensuring robustness with respect to sequence timing. 3D whole-heart PSIR has been integrated with diaphragmatic navigator-gating (NAV) [2] to compensate for respiratory motion. However, both NAV and the need for two different datasets to be acquired (IR and reference) lead to a prohibitively long scanning time. Thus, integrating 1D respiratory Self-Navigation (SN) [3] with 3D-PSIR to obtain 100% scan efficiency is desirable. Unfortunately, signal and contrast variations between the IR and the reference dataset pose a major challenge. Here, we hypothesized that a recently introduced contrast independent iterative approach to 1D SN (IT-SN) [4] effectively suppresses respiratory motion in 3D-PSIR acquisitions.