Abstract
BackgroundData on left ventricular (LV) function in patients with neurocardiogenic syncope (NS) is conflicting in adults and lacking in children. The aim of this study was to analyze LV myocardial performance in children with NS at rest and during head-up tilt-table (HUTT) testing.MethodsThis is the first study to combine HUTT and speckle-tracking echocardiography (STE) in children with NS. 43 consecutive normotensive pediatric patients with NS (mean age 13.9 ± 2.6 years, 51% female) and 41 sex- and age-matched healthy controls were included in the study. The study groups consisted of 21 patients with a positive HUTT reaction (HUTT+) and 22 with a negative HUTT reaction (HUTT-). STE was used to analyze peak systolic LV myocardial strain and strain rate.ResultsConventional echocardiographic parameters were similar in all analyzed groups. When compared to healthy controls, children with NS had depressed levels of circumferential strain rate (p = 0.032) and significantly depressed longitudinal strain rate (p < 0.001) at rest. Interestingly, during HUTT testing LV global strain and strain rate were similar in both groups. LV strain rate was lowest in HUTT+ followed by HUTT- and control subjects both at rest and during HUTT.ConclusionsResting LV longitudinal strain rate is attenuated in children with NS, especially in those with a positive HUTT response. This is further evidence that NS patients feature altered cardiac mechanics rendering them prone to vasovagal perturbations that can ultimately result in collapse.Trial registrationWitten/Herdecke University ethics committee clinical study number: UWH-73-2014.
Highlights
Data on left ventricular (LV) function in patients with neurocardiogenic syncope (NS) is conflicting in adults and lacking in children
The presence of any acute or chronic condition that might affect the cardiovascular system, ECG abnormalities, chronic medication use and the lack of cooperation to participate in this voluntary head-up tilt-table (HUTT) study were strict exclusion criteria. 60 patients were excluded from the study due to various reasons: 53 were incompliant regarding the HUTT challenge, 2 patients were obese (BMI > 30), 2 had insufficient image quality at baseline and in 3 patients the continuous ECG signal was corrupted due to technical difficulties which made consecutive speckle tracking postprocessing impossible
Height (p = 0.375), body weight (p = 0. 101), body mass index (p = 0.1) and body surface area (p = 0.165) were not statistically different between the three groups. All these values were within normal limits as evaluated by Z-scores
Summary
Data on left ventricular (LV) function in patients with neurocardiogenic syncope (NS) is conflicting in adults and lacking in children. The “ventricular hypothesis” on the other hand is based on an increase in left ventricular (LV) contractility – i.e. due to ventricular underfilling, sympathetic overactivity or hypovolemia. This may result in LV mechanoreceptor activation, the Bezold-Jarisch reflex, which in turn causes systemic hypotension, peripheral vasodilation and severe bradycardia [8]. The origin of the precipitating hemodynamic changes and the specific underlying pathomechanisms resulting in vasovagal syncope in children yet remain a subject of considerable speculation
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