Syncope is common among pediatric patients and is rarely pathologic. The mechanisms for symptoms during exercise are less well understood than the resting mechanisms. Additionally, inert gas rebreathing analysis, a non-invasive examination of haemodynamics including cardiac output, has not previously been studied in youth with neurocardiogenic syncope.

This was a retrospective (2017–2023), single-center cohort study in pediatric patients ≤ 21 years with prior peri-exertional syncope evaluated with echocardiography and cardiopulmonary exercise testing with inert gas rebreathing analysis performed on the same day. Patients with and without symptoms during or immediately following exercise were noted.

Of the 101 patients (15.2 ± 2.3 years; 31% male), there were 22 patients with symptoms during exercise testing or recovery. Resting echocardiography stroke volume correlated with resting (r = 0.53, p < 0.0001) and peak stroke volume (r = 0.32, p = 0.009) by inert gas rebreathing and with peak oxygen pulse (r = 0.61, p < 0.0001). Patients with syncopal symptoms peri-exercise had lower left ventricular end-diastolic volume (Z-score –1.2 ± 1.3 vs. –0.36 ± 1.3, p = 0.01) and end-systolic volume (Z-score –1.0 ± 1.4 vs. −0.1 ± 1.1, p = 0.001) by echocardiography, lower percent predicted peak oxygen pulse during exercise (95.5 ± 14.0 vs. 104.6 ± 18.5%, p = 0.04), and slower post-exercise heart rate recovery (31.0 ± 12.7 vs. 37.8 ± 13.2 bpm, p = 0.03).

Among youth with a history of peri-exertional syncope, those who become syncopal with exercise testing have lower left ventricular volumes at rest, decreased peak oxygen pulse, and slower heart rate recovery after exercise than those who remain asymptomatic. Peak oxygen pulse and resting stroke volume on inert gas rebreathing are associated with stroke volume on echocardiogram.

Haematopoietic stem cell transplantation is an important and effective treatment strategy for many malignancies, marrow failure syndromes, and immunodeficiencies in children, adolescents, and young adults. Despite advances in supportive care, patients undergoing transplant are at increased risk to develop cardiovascular co-morbidities.

This study was performed as a feasibility study of a rapid cardiac MRI protocol to substitute for echocardiography in the assessment of left ventricular size and function, pericardial effusion, and right ventricular hypertension.

A total of 13 patients were enrolled for the study (age 17.5 ± 7.7 years, 77% male, 77% white). Mean study time was 13.2 ± 5.6 minutes for MRI and 18.8 ± 5.7 minutes for echocardiogram (p = 0.064). Correlation between left ventricular ejection fraction by MRI and echocardiogram was good (ICC 0.76; 95% CI 0.47, 0.92). None of the patients had documented right ventricular hypertension. Patients were given a survey regarding their experiences, with the majority both perceiving that the echocardiogram took longer (7/13) and indicating they would prefer the MRI if given a choice (10/13).

A rapid cardiac MRI protocol was shown feasible to substitute for echocardiogram in the assessment of key factors prior to or in follow-up after haematopoietic stem cell transplantation.

Operators are mindful of the balloon-to-aortic annulus ratio when performing balloon aortic valvuloplasty. The method of measurement of the aortic valve annulus has not been standardised.

Patients who underwent aortic valvuloplasty at two paediatric centres between 2007 and 2014 were included. The valve annulus measured by echocardiography and angiography was used to calculate the balloon-to-aortic annulus ratio and measurements were compared. The primary endpoint was an increase in aortic insufficiency by ≥2 degrees. Ninety-eight patients with a median age at valvuloplasty of 2.1 months (Interquartile range (IQR): 0.2–105.5) were included. The angiographic-based annulus was 8.2 mm (IQR: 6.8–16.0), which was greater than echocardiogram-based annulus of 7.5 mm (IQR: 6.1–14.8) (p < 0.001). This corresponded to a significantly lower angiographic balloon-to-aortic annulus ratio of 0.9 (IQR: 0.9–1.0), compared to an echocardiographic ratio of 1.1 (IQR: 1.0–1.1) (p < 0.001). The degree of discrepancy in measured diameter increased with smaller valve diameters (p = 0.041) and in neonates (p = 0.044). There was significant disagreement between angiographic and echocardiographic balloon-to-aortic annulus ratio measures regarding “High” ratio of >1.2, with angiographic ratio flagging only 2/12 (16.7%) of patients flagged by echocardiographic ratio as “High” (p = 0.012). Patients who had an increase in the degree of aortic insufficiency post valvuloplasty, only 3 (5.5%) had angiographic ratio > 1.1, while 21 (38%) had echocardiographic ratio >1.1 (p < 0.001). Patients with resultant ≥ moderate insufficiency more often had an echocardiographic ratio of >1.1 than angiographic ratio of >1.1 There was no association between increase in balloon-to-aortic annulus ratio and gradient reduction.

Angiographic measurement is associated with a greater measured aortic valve annulus and the development of aortic insufficiency. Operators should use caution when relying solely on angiographic measurement when performing balloon aortic valvuloplasty.