Background
Head up Tilt‐table Test (HUTT) is a practical examination of the most common type of pediatrics syncope. The electrocardiographic (ECG) changes during this test, show the autonomic defects ...that cause neuraly‐mediated syncope in response to tilting process.
Methods
All pediatric syncope patients referred to our center in a 1‐year period, were included in the study. HUTT was performed and patients were classified into two groups of Negative and Positive HUTT results, and the latter group was subclassified as three subgroups of “vasodepressor”, “cardioinhibitory” and “mixed type” responses to HUTT. QT and corrected QT (QTc) dispersion was measured by the baseline standard 12‐lead ECG obtained before HUTT.
Results
Eighty‐six patients with a mean age of 12.19 ± 5.34 were included. Patients with positive HUTT were significantly younger and male gender was more prevalent in this group. Mean QT dispersion was significantly higher in patients with positive HUTT result and also in patients with mixed response to HUTT compared to isolated vasodepressor response. Duration of QTc interval did not change between different study groups. Reciever‐Operating‐Characteristic (ROC) analysis showed that QT dispersion higher than 32 ms is a significant predictor of positive HUTT result (with 92% sensitivity and 98% specificity) and values higher than 40 ms can predict the mixed type of response to HUTT (with 84% sensitivity and 63% specificity).
Conclusions
Baseline myocardial repolarization disparity significantly correlates with susceptibility to symptomatic vasovagal syncope. This pathology seems to play its role mainly via excessive vagotonic response to sympathetic activation during HUTT process (known as cardioinhibitory response).
Highlights • Tilt table testing helps to differentiate the forms of transient loss of consciousness (TLOC) and of syncope. • Tilt table testing adds to history taking, and cannot be used as its ...substitution. • Neurologists and clinical neurophysiologists can play an important role diagnosing syncope or other forms of TLOC, given their experience with extensive history taking.
•Sensitive, validated, noninvasive electrodiagnostic tests of autonomic function have been developed.•An international expert panel provides evidence-based recommendations to guide autonomic ...testing.•Recommendations allow for standardized assessment of severity and distribution of autonomic failure.
Evaluation of disorders of the autonomic nervous system is both an art and a science, calling upon the physician’s most astute clinical skills as well as knowledge of autonomic neurology and physiology. Over the last three decades, the development of noninvasive clinical tests that assess the function of autonomic nerves, the validation and standardization of these tests, and the growth of a large body of literature characterizing test results in patients with autonomic disorders have equipped clinical practice further with a valuable set of objective tools to assist diagnosis and prognosis. This review, based on current evidence, outlines an international expert consensus set of recommendations to guide clinical electrodiagnostic autonomic testing. Grading and localization of autonomic deficits incorporates scores from sympathetic cardiovascular adrenergic, parasympathetic cardiovagal, and sudomotor testing, as no single test alone is sufficient to diagnose the degree or distribution of autonomic failure. The composite autonomic severity score (CASS) is a useful score of autonomic failure that is normalized for age and gender. Valid indications for autonomic testing include generalized autonomic failure, regional or selective system syndromes of autonomic impairment, peripheral autonomic neuropathy and ganglionopathy, small fiber neuropathy, orthostatic hypotension, orthostatic intolerance, syncope, neurodegenerative disorders, autonomic hyperactivity, and anhidrosis.
Opinions differ regarding the effectiveness of cardiac pacing in patients affected by reflex syncope. We assessed a standardized guideline-based algorithm in different forms of reflex syncope.
In ...this prospective, multi-centre, observational study, patients aged >40 years, affected by severe unpredictable recurrent reflex syncopes, underwent carotid sinus massage (CSM), followed by tilt testing (TT) if CSM was negative, followed by implantation of an implantable loop recorder (ILR) if TT was negative. Those who had an asystolic response to one of these tests received a dual-chamber pacemaker.
253 patients, mean age 70 ± 12 years, median 4 (3-6) syncopes, 89% without or with short prodromes. Of these patients, 120 (47%) received a pacemaker and 106 were followed up for a mean of 13 ± 7 months: syncope recurred in 10 (9%). The recurrence rate was similar in 61 CSM+ (11%), 30 TT+ (7%), and 15 ILR+ (7%) patients. The actuarial total syncope recurrence rate was 9% (95% confidence interval (CI), 6-12) at 1 year and 15% (95% CI, 10-20) at 2 years and was significantly lower than that observed in the group of 124 patients with non-diagnostic tests who had received an ILR: i.e. 22% (95% CI, 18-26) at 1 year and 37% (95% CI, 30-43) at 2 years (P = 0.004).
About half of older patients with severe recurrent syncopes without prodromes have an asystolic reflex for which cardiac pacing goes along with a low recurrence rate. The study supports the clinical utility of the algorithm for the selection of candidates to cardiac pacing in everyday clinical practice.
http://www.clinicaltrials.gov. Unique identifier: NCT01509534.
Abstract
Aims
A dual-chamber pacemaker with closed-loop stimulation (CLS) mode is effective in reducing syncopal recurrences in patients with asystolic vasovagal syncope (VVS). In this study, we ...explored the haemodynamic and temporal relationship of CLS during a tilt-induced vasovagal reflex.
Methods and results
Twenty patients underwent a tilt test under video recording 3.9 years after CLS pacemaker implantation. Three patients were excluded from the analysis because of no VVS induced by the tilt test (n = 1) and protocol violation (n = 2). In 14 of the remaining 17 patients, CLS pacing emerged during the pre-syncopal phase of circulatory instability when the mean intrinsic heart rate (HR) was 88 ± 12 b.p.m. and systolic blood pressure (SBP) was 108 ± 19 mmHg. The CLS pacing rate thereafter rapidly increased to 105 ± 14 b.p.m. within a median of 0.1 min inter-quartile range (IQR), 0.1–0.7 min when the SBP was 99 ± 21 mmHg. At the time of maximum vasovagal effect (syncope or pre-syncope), SBP was 63 ± 17 mmHg and the CLS rate was 95 ± 13 b.p.m. The onset of CLS pacing was 1.7 min (IQR, 1.5–3.4) before syncope or lowest SBP. The total duration of CLS pacing was 5.0 min (IQR, 3.3–8.3). Closed-loop stimulation pacing was not observed in three patients who had a similar SBP decrease from 142 ± 22 mmHg at baseline to 69 ± 4 mmHg at the time of maximum vasovagal effect, but there was no significant increase in HR (59 ± 1 b.p.m.).
Conclusion
The reproducibility of a vasovagal reflex was high. High-rate CLS pacing was observed early during the pre-syncopal phase in most patients and persisted, although attenuated, at the time of maximum vasovagal effect.
Registration
ClinicalTrials.gov identifier: NCT06038708
Graphical Abstract
Graphical Abstract
Background: Patients with unexplained syncope should undergo the tilt table test, it is the only clinical laboratory test indicated to identify susceptibility to vasovagal fainting.The Aim of the ...work: To evaluate the effect of sublingual nitrates Nitroglycerine on the result of tilt table test in patients with unexplained syncope.Patients and Methods: This was prospective observational study enrolled 60 patients with history of unexplained syncope. patients with cardiac or neurologic syncope were excluded. All patients were subjected to thorough history taking, physical examination blood pressure, pulse and complete cardiac examination, standard 12 lead electro-cardiography, transthoracic echocardiography, passive tilt table test for 45 minutes with negative response and provocation tilt table test by sublingual isosorbide dinitrate for 15 minutes.Results: After provocation by isosorbide dinitrate 5 mg, 38 patients 63.3 % turned from negative to a positive response. The most common type was Vasodepressor 35 %. There was a statistically significant increase in heart rate from passive stage to provocation stage in positive patients P <0.001 and in negative patients P <0.001, While there was a statistically significant decrease in blood pressure in positive patients P <0.001 and in negative patients P <0.001. There is no statistically significant difference between males and females regarding test results P = 0.464 or type of response P = 0.727. There was no statistically significant difference between positive and negative patients regarding comorbidities, smoking P =0.552, diabetes mellitus P = 0.879, hypertension P = 0.338, or medications, angiotensin converting enzyme inhibitors P = 0.419, beta blockers P = 0.636, calcium channel blockers P = 0.616.Conclusion: The sublingual nitroglycerine has positive impact on the result of tilt table test in individuals with unexplained syncope. Gender, comorbidities and medications didn’t affect the result of tilt table test.
Background: Distinguishing between seizure and neurally mediated syncope is challenging because of similar consequences and medical history. A head-up tilt test (HUTT) is a non-invasive, simple, and ...easy test to distinguish between epilepsy and syncope besides detailed history taking. Objectives: This study aimed to differentiate between epileptic events and reflex syncope (any different type of syncope) using the head-upright tilt test. Methods: We studied 59 patients (37 boys and 22 girls) between 4 to 18 years old (mean age, 10.5 ± 3.7 years) with a previous diagnosis of seizure who did not respond well to treatment. All patients underwent HUTT, and the test was positive in 26 patients. There were no significant differences in sex, age, provocative factors, associated syndrome, and family history between negative and positive groups. Results: There was a history of actual syncope in 26.9% of the positive tilt test group compared to 15.15% of the negative test group. Also, there was a positive family history of syncope in the positive tilt test group. Among 26 patients with a positive tilt test, 17 were diagnosed with vasovagal syncope (VVS) vasodepressor type and 9 with mixed type. Antiepileptic drugs were tapered for patients diagnosed with VVS, and they did not show any seizures after 18 ± 6 months of follow-up. Overemphasizing positive family history and inattention to history taking are 2 crucial factors leading to the misdiagnosis of epilepsy. Conclusions: Our study showed that HUTT is a non-invasive test that can be useful, especially for early and proper diagnosis in children with refractory epilepsy.
In part I of this study, we found that the classical studies on vasovagal syncope, conducted in fit young subjects, overstated vasodilatation as the dominant hypotensive mechanism. Since 1980, blood ...pressure and cardiac output have been measured continuously using noninvasive methods during tilt, mainly in patients with recurrent syncope, including women and the elderly. This has allowed us to analyze in more detail the complex sequence of hemodynamic changes leading up to syncope in the laboratory. All tilt-sensitive patients appear to progress through 4 phases: (1) early stabilization, (2) circulatory instability, (3) terminal hypotension, and (4) recovery. The physiology responsible for each phase is discussed. Although the order of phases is consistent, the time spent in each phase may vary. In teenagers and young adults, progressive hypotension during phases 2 and 3 can be driven by vasodilatation or falling cardiac output. The fall in cardiac output is secondary to a progressive decrease in stroke volume because blood is pooled in the splanchnic veins. In adults a fall in cardiac output is the dominant hypotensive mechanism because systemic vascular resistance always remains above baseline levels.
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