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.

Cardiopulmonary exercise test (CPET) allows quantification of functional capacity of patients with Fontan. The objective of this study was to determine the role of CPET parameters in predicting a higher maximum oxygen consumption (VO2 max) and to analyse the role of CPET parameters in predicting an unfavourable outcome.

A retrospective, cross-sectional, descriptive study was carried out on 57 patients with Fontan, who had undergone incremental CPET with cycloergometer between 2010 and 2020. Determinants of VO2 max and determinants of clinical deterioration were analysed.

In the univariate analysis, the variables significantly related to VO2 max were: age, sex, body mass index (BMI), years of Fontan evolution, intracardiac Fontan, oxygen consumption at anaerobic threshold (VO2AT), CO2 equivalents at anaerobic threshold (VE/VCO2) and chronotropic insufficiency. The multiple linear regression model that best fitted the relationship between VO2 max and independent variables (correlation coefficient 0.73) included sex (correlation index 3.35; p = 0.02), BMI (−0.27; p = 0.02), chronotropic failure (−2.79; p = 0.01) and VO2AT (0.92; p < 0.0001). In the univariate analysis of the prognostic CPET variables related to an unfavourable clinical situation, significance was only obtained with chronotropic insufficiency (p = 0.003). In multivariate analysis, chronotropic insufficiency maintains its association [p= 0.017, OR = 4.65 (1.3–16.5)].

In conclusion, together with the anthropometric parameters universally related to VO2 max, chronotropic insufficiency and VO2AT are the main determinants of functional capacity in patients with Fontan. Moreover, chronotropic insufficiency is closely related to unfavourable clinical evolution. Our data would support the intensive treatment of chronotropic insufficiency in order to improve the quality of life and the clinical situation of patients with Fontan.

Regular evaluation of physical capacity takes a crucial part in long-term follow-up in patients with congenital heart disease (CHD). This study aims to examine the accuracy of self-estimated exercise capacity compared to objective assessments by cardiopulmonary exercise testing in patients with CHD of various complexity.

We conducted a single centre, cross-sectional study with retrospective analysis on 382 patients aged 8–68 years with various CHD who completed cardiopulmonary exercise tests. Peak oxygen uptake was measured. Additionally, questionnaires covering self-estimation of exercise capacity were completed. Peak oxygen uptake was compared to patient’s self-estimated exercise capacity with focus on differences between complex and non-complex defects.

Peak oxygen uptake was 25.5 ± 7.9 ml/minute/kg, corresponding to 75.1 ± 18.8% of age- and sex-specific reference values. Higher values of peak oxygen uptake were seen in patients with higher subjective rating of exercise capacity. However, oxygen uptake in patients rating their exercise capacity as good (mean oxygen uptake 78.5 ± 1.6%) or very good (mean oxygen uptake 84.8 ± 4.8%) was on average still reduced compared to normal. In patients with non-complex cardiac defects, we saw a significant correlation between peak oxygen uptake and self-estimated exercise capacity (spearman-rho −0.30, p < 0.001), whereas in patients with complex cardiac defects, no correlation was found (spearman-rho −0.11, p < 0.255).

The mismatch between self-estimated and objectively assessed exercise capacity is most prominent in patients with complex CHD.

Registration number at Charité Universitätsmedizin Berlin Ethics Committee: EA2/106/14.

A transannular patch is often used in the contemporary surgical repair of tetralogy of Fallot. This can lead to significant pulmonary insufficiency and increased right ventricular volumes and ultimately pulmonary valve replacement. Cardiopulmonary exercise testing is used to assess exercise capacity in tetralogy of Fallot patients before pulmonary valve replacement. There is only few published literatures on how lung function affects functional capacity in tetralogy of Fallot patients repaired with a transannular patch.

A retrospective chart review was done from 2015 to 2017 on patients with tetralogy of Fallot who underwent maximal effort cardiopulmonary exercise testing with cycle ergometry and with concurrent pulmonary function testing. Tetralogy of Fallot patients repaired with a transannular patch without pulmonary valve replacement were compared with age, gender, and size-matched normal controls.

In the tetralogy of Fallot group, 24 out of 57 patients underwent primary repair with a transannular patch. When compared to the normal controls, they demonstrated abnormal predicted forced expiratory volume in one second (79 ± 23.1% versus 90.7 ± 14.1%, p<0.05), predicted maximal voluntary ventilation (74 ± 18% versus 90.5 ± 16.2%, p<0.05) while having low-normal predicted forced vital capacity (80.5 ± 17.2% versus 90.2 ± 12.4%, p<0.05) and normal breathing reserve percentage (50.3 ± 11.3% versus 47.5 ± 17.3%, p = 0.52). Cardiopulmonary exercise testing abnormalities included significantly lower percent predicted oxygen consumption (63.2 ± 12.2% versus 87 ± 12.1%, p<0.05), maximal heart rate (171.8 ± 18.9 versus 184.6 ± 13.6, p<0.05), and percent predicted maximum workload (61.7 ± 15.9% versus 88.3 ± 21.5%, p<0.05).

Tetralogy of Fallot patients repaired with a transannular patch can have abnormal pulmonary function testing with poor exercise capacity in addition to chronotropic incompetence and impaired muscular power.

Systemic right ventricular systolic dysfunction is common late after atrial switch surgery for transposition of the great arteries. Total isovolumic time is the time that the ventricle is neither ejecting nor filling and is calculated without relying on geometric assumptions. We assessed resting total isovolumic time in this population and its relationship to exercise capacity.

A total of 40 adult patients with transposition of the great arteries after atrial switch – and 10 healthy controls – underwent transthoracic echocardiography and cardiopulmonary exercise testing from January, 2006 to January, 2009. Resting total isovolumic time was measured in seconds per minute: 60 minus total ejection time plus total filling time.

The mean age was 31.6 plus or minus 7.6 years, and 38.0% were men. There were 16 patients (40%) who had more than or equal to moderate systolic dysfunction of the right ventricle. Intra- and inter-observer agreement was good for total isovolumic time, which was significantly prolonged in patients compared with controls (12.0 plus or minus 3.9 seconds per minute versus 6.0 plus or minus 1.8 seconds per minute, p-value less than 0.001) and correlated significantly with peak oxygen consumption (r equals minus 0.63, p-value less than 0.001). The correlation strengthened (r equals minus 0.73, p-value less than 0.001) after excluding seven patients with exercise-induced cyanosis. No relationship was found between exercise capacity and right ventricular ejection fraction or long-axis amplitude.

Resting isovolumic time is prolonged after atrial switch for patients with transposition of the great arteries. It is highly reproducible and relates well to exercise capacity.