Non-invasive in-utero quantification of vascular reactivity in human placenta.

OBJECTIVE: Placental vascular reactivity (PlVR) indicates the ability of the placental vasculature to match blood supply to fetal demand. Many pregnancy disorders alter the characteristics of PlVR, resulting in suboptimal oxygen delivery, although current understanding is limited by the lack of non-invasive, repeatable methods to measure PlVR in utero. Our objective was to quantify PlVR by measuring the placental response to transient changes in maternal carbon dioxide (CO2) using blood-oxygen-level-dependent (BOLD) magnetic resonance imaging (MRI). We hypothesized that PlVR will increase with gestational age to meet the changing demands of a growing fetus, and that PlVR will be driven by a maternal response to changes in CO2 concentration. METHODS: This was a cross-sectional study of 35 women with a healthy singleton pregnancy, of whom 31 were included in the analysis. The median gestational age was 32.6 (range, 22.6-38.4) weeks. Pregnant women were instructed to follow audiovisual breathing cues during a MRI scan. Maternal end-tidal CO2 (EtCO2) was measured concurrently with resting placental BOLD MRI for a total of 7-8 min. Preprocessing of magnetic resonance images consisted of manual delineation of placental anatomy and motion correction. In each placental voxel, vascular reactivity was computed using a coherence-weighted general linear model between MRI signal and EtCO2 stimulus. Global PlVR was computed as the mean of voxel-wise PlVR values across the placenta. RESULTS: PlVR, quantified by the placental response to induced, transient changes in maternal CO2, was consistently measured in utero using BOLD MRI. PlVR increased non-linearly with advancing gestational age (P < 0.001) and was higher on the fetal side of the placenta. PlVR was associated positively with fetal brain volume after accounting for gestational age. PlVR did not show any significant associations with maternal characteristics. CONCLUSIONS: We present, for the first time, a non-invasive paradigm to quantify PlVR in ongoing human pregnancies without the use of exogenous gases or contrast agents. Our findings suggest that PlVR is driven by a fetal response to changes in maternal CO2. Ease of translation to the clinical setting makes PlVR a promising biomarker for the identification and management of high-risk pregnancies. © 2023 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Bisphosphonate therapy in an infant with generalized arterial calcification with an ABCC6 mutation.

Generalized arterial calcification of infancy (GACI) is a rare genetic disorder with high infantile mortality, described to be due to ENPP1, and less commonly ABCC6 mutations. Bisphosphonate treatment has been described to improve survival in ENPP1-positive GACI patients, but few studies have described bisphosphonate treatment in ABCC6-positive patients. Without therapy, patients will die before 6 months of age. Our patient is now 3 years old, former recipient twin of twin-to-twin transfusion syndrome (TTTS). Initial fetal echocardiogram at 19 weeks showed calcifications of the ascending aorta and pulmonary artery (PA). She underwent utero laser therapy, and despite resolution of the TTTS, her follow-up scans showed progressive calcification of the aorta and PA. Postnatal echocardiogram showed calcification and supravalvar stenosis of the aorta and PA. CT on day of life 6 showed calcifications in the PAs, aortic arch, and descending aorta. Quantification of valvular calcification can be difficult; in our patient, increasing outflow tract gradient on echocardiogram was used to monitor disease progression. Molecular testing revealed an ABCC6 gene mutation. She was started on weekly IV pamidronate (0.1-0.3 mg/kg/week) on day 8 of life then transitioned to oral etidronate (15-20 mg/kg/day). Given progressive supravalvar aortic and pulmonary stenosis, she underwent surgical repair with patch augmentation of the PA and ascending aorta at 4 months old. She has done well post-operatively, continuing on enteral bisphosphonate therapy with no side effects to date. Her identical twin was confirmed to have the same mutation and remains asymptomatic with no calcifications. Aggressive bisphosphonate therapy should be started as soon as possible in patients with infantile arterial calcinosis due to ABCC6 or ENPP1 mutations. Echocardiographic evaluation can be used to monitor disease progression by arterial gradients. Molecular testing is also essential to evaluate for possible co-morbidities in these patients and pregnancy management for the future.

Assessment of fetal cardiomyopathy in early-stage twin-twin transfusion syndrome: comparison between commonly reported cardiovascular assessment scores.

OBJECTIVES: To assess the relationship between commonly reported fetal cardiomyopathy scoring systems in early-stage twin-twin transfusion syndrome (TTTS). METHODS: We reviewed retrospectively 100 cases of Quintero Stages I and II TTTS referred to our center for evaluation from 2008 to 2010. The cases were divided into groups of 25, representing each of four grades of TTTS cardiomyopathy as assessed by Cincinnati stage: no cardiomyopathy, Stage IIIa, Stage IIIb and Stage IIIc. Spearman correlation (rs ) was calculated between the Children's Hospital of Philadelphia (CHOP) score, cardiovascular profile score (CVPS), Cincinnati stage and myocardial performance index (MPI). RESULTS: There was a weak correlation between the Cincinnati stage and the CHOP score (rs = 0.36) and CVPS (rs = -0.39), while correlation was strong between the CHOP score and CVPS (rs = -0.72). MPI elevation was concordant with Cincinnati stage more frequently (82% of cases) than were ventricular hypertrophy (43%) or atrioventricular valve regurgitation (28%). 51% of fetuses with minimally elevated CHOP score (0-1) and 48% of fetuses with minimally depressed CVPS (9-10) had significant elevation (Z-score ≥ +3) in right ventricular or left ventricular MPI. CONCLUSIONS: MPI has a strong influence on grading the severity of fetal cardiomyopathy using the Cincinnati stage among fetuses with mild TTTS. Furthermore, significant elevation of the MPI is common among fetuses with mild disease as assessed by the CHOP score and CVPS. These differences should be understood when assessing and grading cardiomyopathy in TTTS, particularly in early (Quintero Stages I and II) disease.

Bosentan for increased pulmonary vascular resistance in a patient with single ventricle physiology and a bidirectional Glenn shunt.

We present a case of the successful use of bosentan for increased pulmonary vascular resistance (PVR) in a 10-year-old male who underwent late single ventricle surgical palliation for double-inlet left ventricle with pulmonary artery banding and a bidirectional Glenn shunt. The patient was treated with bosentan for 16 weeks, with decreases in mean pulmonary artery pressure from 23 to 16 mmHg on the right and from 31 to 21 mmHg on the left, and a decrease of the transpulmonary gradient by 7-8 mmHg. Cardiopulmonary exercise testing demonstrated an increase in peak oxygen consumption (VO2) by 8% and peak work rate by 10%. Bosentan is a relatively new oral therapy option for increased PVR in patients with single ventricle physiology and bidirectional Glenn shunts.