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The arterial switch operation (ASO) is the standard surgical treatment for transposition of the great arteries (TGA). Postoperative complications such as branch pulmonary artery (PA) stenosis are commonly observed. This study aimed to investigate the possible potential anatomical mechanisms contributing to isolated branch PA stenosis using cardiac computed tomography (CCT). A retrospective, single-center study was conducted on pediatric patients under 18 years of age diagnosed with TGA, with or without ventricular septal defect (VSD), who underwent ASO and cardiac CCT between January 2004 and October 2022. Baseline characteristics, echocardiographic data, and CCT findings were compared between patients with and without isolated branch PA stenosis. Special attention was given to the angle between the PA bifurcation and the ascending aorta (AAO). Among 30 patients enrolled, 46.67% (14/30) had isolated branch PA stenosis, while 53.33% (16/30) had no stenosis. Baseline and echocardiographic variables showed no significant differences between groups, except for the PA bifurcation angle relative to the AAO. Patients with isolated right PA (RPA) stenosis demonstrated significantly greater leftward angulation (median angle: 25° [IQR: 24, 30]) compared to the no-stenosis group (median angle: -2° [IQR: -8, 6.5]). Similarly, isolated left PA (LPA) stenosis was associated with greater rightward angulation (median angle: -22° [IQR: -32, -20]) compared to the no-stenosis group (P = 0.042). Alterations in the PA bifurcation angle relative to the AAO may contribute to the development of isolated branch PA stenosis following ASO. Preoperative planning to optimize the PA bifurcation angle to within ±20 degrees may help reduce the risk of postoperative stenosis. A larger study incorporating advanced cardiac imaging into routine ASO follow-up is warranted.

Iron bioavailability has been identified as a factor that influences cellular hypoxia sensing, putatively via an action on the hypoxia-inducible factor (HIF) pathway. We therefore hypothesized that clinical iron deficiency would disturb integrated human responses to hypoxia. We performed a prospective, controlled, observational study of the effects of iron status on hypoxic pulmonary hypertension. Individuals with absolute iron deficiency (ID) and an iron-replete (IR) control group were exposed to two 6-hour periods of isocapnic hypoxia. The second hypoxic exposure was preceded by i.v. infusion of iron. Pulmonary artery systolic pressure (PASP) was serially assessed with Doppler echocardiography. Thirteen ID individuals completed the study and were age- and sex-matched with controls. PASP did not differ by group or study day before each hypoxic exposure. During the first 6-hour hypoxic exposure, the rise in PASP was 6.2 mmHg greater in the ID group (absolute rises 16.1 and 10.7 mmHg, respectively; 95% CI for difference, 2.7-9.7 mmHg, P = 0.001). Intravenous iron attenuated the PASP rise in both groups; however, the effect was greater in ID participants than in controls (absolute reductions 11.1 and 6.8 mmHg, respectively; 95% CI for difference in change, -8.3 to -0.3 mmHg, P = 0.035). Serum erythropoietin responses to hypoxia also differed between groups. Clinical iron deficiency disturbs normal responses to hypoxia, as evidenced by exaggerated hypoxic pulmonary hypertension that is reversed by subsequent iron administration. Disturbed hypoxia sensing and signaling provides a mechanism through which iron deficiency may be detrimental to human health. ClinicalTrials.gov (NCT01847352). M.C. Frise is the recipient of a British Heart Foundation Clinical Research Training Fellowship (FS/14/48/30828). K.L. Dorrington is supported by the Dunhill Medical Trust (R178/1110). D.J. Roberts was supported by R&D funding from National Health Service (NHS) Blood and Transplant and a National Institute for Health Research (NIHR) Programme grant (RP-PG-0310-1004). This research was funded by the NIHR Oxford Biomedical Research Centre Programme.

Abstract Rationale Vascular alteration of small pulmonary vessels is one of the characteristic features of pulmonary hypertension in chronic obstructive pulmonary disease. The in vivo relationship between pulmonary hypertension and morphological alteration of the small pulmonary vessels has not been assessed in patients with severe emphysema. Objectives We evaluated the correlation of total cross-sectional area of small pulmonary vessels (CSA) assessed on computed tomography (CT) scans with the degree of pulmonary hypertension estimated by right heart catheterization. Methods In 79 patients with severe emphysema enrolled in the National Emphysema Treatment Trial (NETT), we measured CSA less than 5 mm2 (CSA<5) and 5 to 10 mm2 (CSA5−10), and calculated the percentage of total CSA for the lung area (%CSA<5 and %CSA5–10, respectively). The correlations of %CSA<5 and %CSA5–10 with pulmonary arterial mean pressure (Ppa¯) obtained by right heart catheterization were evaluated. Multiple linear regression analysis using Ppa¯ as the dependent outcome was also performed. Measurements and Main Results The %CSA<5 had a significant negative correlation with Ppa¯ (r = −0.512, P < 0.0001), whereas the correlation between %CSA5–10 and Ppa¯ did not reach statistical significance (r = −0.196, P = 0.083). Multiple linear regression analysis showed that %CSA<5 and diffusing capacity of carbon monoxide (DlCO) % predicted were independent predictors of Ppa¯ (r2 = 0.541): %CSA <5 (P < 0.0001), and DlCO % predicted (P = 0.022). Conclusions The %CSA<5 measured on CT images is significantly correlated to Ppa¯ in severe emphysema and can estimate the degree of pulmonary hypertension.

Objectives To evaluate the feasibility of T1w-3D black-blood turbo spin echo (TSE) sequence with variable flip angles for the diagnosis of thoracic large vessel vasculitis (LVV). Methods Thirty-five patients with LVV, diagnosed according to the current standard of reference, and 35 controls were imaged at 3.0T using 1.2 × 1.3 × 2.0 mm 3 fat-suppressed, T1w-3D, modified Volumetric Isotropic TSE Acquisition (mVISTA) pre- and post-contrast. Applying a navigator and peripheral pulse unit triggering (PPU), the total scan time was 10–12 min. Thoracic aorta and subclavian and pulmonary arteries were evaluated for image quality (IQ), flow artefact intensity, diagnostic confidence, concentric wall thickening and contrast enhancement (CWT, CCE) using a 4-point scale. Results IQ was good in all examinations (3.25 ± 0.72) and good to excellent in 342 of 408 evaluated segments (83.8 %), while 84.1 % showed no or minor flow artefacts. The interobserver reproducibility for the identification of CCE and CWT was 0.969 and 0.971 (p < 0.001) with an average diagnostic confidence of 3.47 ± 0.64. CCE and CWT were strongly correlated (Cohen’s k = 0.87; P < 0.001) and significantly more frequent in the LVV-group (52.8 % vs. 1.0 %; 59.8 % vs. 2.4 %; P < 0.001). Conclusions Navigated fat-suppressed T1w-3D black-blood MRI with PPU-triggering allows diagnosis of thoracic LVV. Key Points • Cross-sectional imaging is frequently applied in the diagnosis of LVV. • Navigated, PPU-triggered, T1w-3D mVISTA pre- and post contrast takes 10–12 min. • In this prospective, single-centre study, T1w-3D mVISTA accurately depicted large thoracic vessels. • T1w-3D mVISTA visualized CWT/CCW as correlates of mural inflammation in LVV. • T1w-3D mVISTA might be an alternative diagnostic tool without ionizing radiation.

Objectives To investigate the effect of a device-assisted suction against resistance Mueller maneuver (MM) on transient interruption of contrast (TIC) in the aorta and pulmonary trunk (PT) on computed tomography pulmonary angiogram (CTPA). Methods In this prospective single-center study, 150 patients with suspected pulmonary artery embolism were assigned randomly with two different breathing maneuvers (Mueller maneuver (MM) or standard end-inspiratory breath-hold command (SBC)) during routine CTPA. The MM was performed using a patented prototype (Contrast Booster™) which allows both the patient by means of visual feedback and the medical staff in the CT scanning room to monitor whether the patient is sucking sufficiently or not. Mean Hounsfield attenuation in descending aorta and PT was measured and compared. Results Overall, patients with MM showed an attenuation of 338.24 HU in the pulmonary trunk, compared to 313.71 HU in SBC ( p  = 0.157). In the aorta, the values for MM were lower compared to SBC (134.42 HU vs. 177.83 HU, p  = 0.001). The TP-aortic ratio was significantly higher in the MM group at 3.86 compared to the SBC group at 2.26, p  = 0.001. TIC phenomenon was absent in the MM group, whereas it was present in 9 patients (12.3%) in the SBC group ( p  = 0.005). Overall contrast was better on all levels for MM ( p  < 0.001). The presence of breathing artifacts was higher in the MM group (48.1% vs. 30.1%, p  = 0.038), without clinical consequence. Conclusions Performing the MM with the application of the prototype is an effective way of preventing the TIC phenomenon during i.v. contrast-enhanced CTPA scanning compared to the standard end-inspiratory breathing command. Clinical relevance Compared to standard end-inspiratory breathing command, the device-assisted Mueller maneuver (MM) improves contrast enhancement and prevents the transient interruption of contrast (TIC) phenomenon in CTPA. Therefore, it may offer optimized diagnostic workup and timely treatment for patients with pulmonary embolism. Key Points • Transient interruption of contrast (TIC) may impair image quality in CTPA. • Mueller Maneuver using a device prototype could lower the rate of TIC. • Device application in clinical routine may increase diagnostic accuracy.

The Single Ventricle Reconstruction (SVR) Trial was a randomized prospective trial designed to determine survival advantage of the modified Blalock-Taussig-Thomas shunt (BTTS) vs the right ventricle to pulmonary artery conduit (RVPAS) for patients with hypoplastic left heart syndrome. The primary aim of the long-term follow-up (SVRIII) was to determine the impact of shunt type on RV function. In this work, we describe the use of CMR in a large cohort follow up from the SVR Trial as a focused study of single ventricle function. The SVRIII protocol included short axis steady-state free precession imaging to assess single ventricle systolic function and flow quantification. There were 313 eligible SVRIII participants and 237 enrolled, ages ranging from 10 to 12.5 years. 177/237 (75%) participants underwent CMR. The most common reasons for not undergoing CMR exam were requirement for anesthesia ( n  = 14) or ICD/pacemaker ( n  = 11). A total of 168/177 (94%) CMR studies were diagnostic for RVEF. Median exam time was 54 [IQR 40–74] minutes, cine function exam time 20 [IQR 14–27] minutes, and flow quantification time 18 [IQR 12–25] minutes. There were 69/177 (39%) studies noted to have intra-thoracic artifacts, most common being susceptibility artifact from intra-thoracic metal. Not all artifacts resulted in non-diagnostic exams. These data describe the use and limitations of CMR for the assessment of cardiac function in a prospective trial setting in a grade-school-aged pediatric population with congenital heart disease. Many of the limitations are expected to decrease with the continued advancement of CMR technology.

To assess the feasibility and outcome of stent strut dilation after arterial duct stenting with associated branch pulmonary artery (BPA) stenosis. Stenting of arterial duct in infants with duct-dependent pulmonary circulation is technically challenging. The presence of BPA stenosis is a relative contraindication for stent implantation. Infants with duct-dependent pulmonary circulation and associated BPA stenosis were assessed either by transthoracic echocardiogram alone or additional computerized tomography angiogram when required. Following ductal stenting, the stent struts of the stenosed BPA were crossed with an additional 0.014″ coronary guide wire and dilated using coronary balloons (2.0 or 2.5 mm in diameter). Seventeen (12 male) patients were considered for the procedure. The median age and weight were 27 days (range 2–94) and 2.6 kg (range 2.2–5), respectively. Fourteen patients (82.4%) underwent stent strut dilation after arterial duct stenting. Struts to left pulmonary artery was opened in 9 (64.3%) and right pulmonary artery in 5 (35.7%). The mean systemic oxygen saturation increased from 66.23 ± 8.9% at baseline to 86 ± 2.2% immediately after the stent deployment and final saturations after stent strut dilation were 89.29 ± 4.3%. Angiographic pulmonary flow improved in all cases. Stent strut dilation could not be done in 3 patients due to unfavorable anatomy. One patient had acute stent thrombosis and died in the hospital. Two others died during follow-up, during an acute febrile illness and gastroenteritis. All survivors underwent cardiac surgery and were on regular follow-up. Strut dilation of BPA stenosis is feasible to augment pulmonary blood flow, following arterial duct stenting. This procedure may be useful in selected patients with BPA stenosis to have uniform growth of pulmonary arteries.

Objectives To evaluate the image quality, radiation dose and diagnostic accuracy of 80kVp, high-pitch CT pulmonary angiography (CTPA) with iterative reconstruction using 20 ml of contrast agent. Methods One hundred patients with suspected pulmonary embolism (PE) were randomly divided into two groups ( n  = 50 each; group A, 100 kVp, 1.2 pitch, 60 ml of contrast medium and filtered back projection algorithm; group B, 80 kVp, 2.2 pitch, 20 ml of contrast medium and sinogram affirmed iterative reconstruction). Image quality, diagnostic accuracy and radiation dose were evaluated and compared. Results Mean CT numbers of pulmonary arteries in group B were higher than those in group A (all P  < 0.001). Contrast-to-noise ratio and signal-to-noise ratio of group B were higher than those of group A (both P  < 0.001). There was no significant difference in subjective image quality scores between two groups ( P  = 0.807). The interobserver agreement was excellent (k = 0.836). There was no significant difference in diagnostic accuracy between the two groups ( P  > 0.05). Compared with group A, radiation dose of group B was reduced by 50.3 % ( P  < 0.001). Conclusions High-pitch CTPA at 80 kVp can obtain sufficient image quality in normal-weight individuals with 20 ml of contrast agent and half the radiation dose of a conventional CTPA protocol. Key Points • CTPA is feasible at 80 kVp using only 20 ml of contrast agent. • High-pitch CTPA at 80 kVp has an effective dose under 1 mSv. • This CTPA protocol can obtain sufficient image quality in normal-weight individuals.

There is limited experience in evaluating abnormal ductus arteriosus (DA) insertion pattern by contrast-enhanced cardiac computed tomography (cardiac CT) in patients with right-sided obstructive cardiac defects. Retrospective review of 38 infants with right-sided obstructive cardiac defects who underwent a preoperative cardiac CT between 2016 and 2021. We reviewed the types of cardiac lesions, patterns of ductal insertion, frequency of pulmonary artery (PA) stenosis requiring intervention, total dose length product (DLP), and effective radiation dose. Of 38 infants, 45% were female, the median gestational age and weight were 37 (range 34–40) weeks and 2.95 (range 2–4) kg. The most common pathologies were pulmonary atresia with ventricular septal defect (24%) and tetralogy of Fallot (24%). The abnormal ductal insertion patterns were DA inserting into the left PA in 39%, DA bifurcating into branch PA in 32%, and DA inserting into the right PA in 13%. Of the 38 infants, 76% developed branch PA stenosis requiring intervention. Among patients with abnormal DA insertion, 44% required branch PA arterioplasty during their index surgery compared to 17% without abnormal DA insertion. Regardless of the type of abnormal DA insertion, 67% developed bilateral branch PA stenosis over time. The mean DLP was 8 mGy-cm and the mean calculated effective radiation dose was 0.312 mSv. The utilization of contrast-enhanced cardiac CT in infants with right-sided obstructive heart defects can offer crucial insights into abnormal ductus arteriosus insertion patterns. This information is valuable for effective procedure planning and for monitoring the development of branch pulmonary artery stenosis.

Computed tomography pulmonary angiography (CTPA) is usually used for pulmonary embolism (PE) detection. However, the determination of scan timing remains a challenge due to the short scan duration of CTPA. We aimed to develop an optimized test bolus to determine scan delay in CTPA. The time-enhancement curves were obtained by measuring the enhancement within a region of interest in the main pulmonary artery and vein. A total of 70 patients were randomly divided into two groups (n = 35 each): the control group underwent CTPA using the test bolus approach and the test group underwent CTPA using the biphasic time-enhancement curves approach. Tube voltages of 100 kVp and 80 kVp and 20 ml and 10 ml contrast agent were adopted in the control and test groups, respectively. The CT numbers, image quality, PE detection was evaluated. There was a point of intersection between the pulmonary artery and vein test bolus enhancement curves. The scan delay time (T DELAY ) was obtained based on the time at intersection (T CROSS ) and the scan duration (T SD ): T DELAY  = T CROSS − T SD . The mean CT numbers for pulmonary vein in the control were higher than those in the test group (all p < 0.001). The image quality for the pulmonary arteries in the test group was better than that in the control group (p < 0.01), with artifact reduction in the superior vena cava. Segmental PE could be detected using the optimized protocol. The radiation dose and iodine load in the test group were all lower than those in the control (p < 0.01). We established an approach to calculate the scan delay of CTPA, and this approach could be used for CTPA at 80 kVp with 10 ml contrast agent.