Lack of correlation between the responses to tilt testing and adenosine triphosphate test and the mechanism of spontaneous neurally mediated syncope

AIMS

We prospectively correlated the results of tilt testing (TT) and adenosine triphosphate test (ATP) with the findings observed during a spontaneous syncopal relapse by means of an implantable loop recorder (ILR) in patients with a clinical diagnosis of neurally mediated syncope.

METHODS AND RESULTS

We included patients with three or more clinically severe syncopal episodes in the last 2 years without significant electrocardiographic and cardiac abnormalities. Patients with orthostatic hypotension and carotid sinus syncope were excluded. After ILR implantation, patients were followed until the first documented syncope. Among 392 enrolled patients, 343 underwent TT, which was positive in 164 (48%), and 180 ATP test, which was positive in 53 (29%). Syncope was documented by ILR in 106 (26%) patients after a median of 3 months. Patients with positive and negative TT had similar baseline characteristics, syncopal recurrence rate, and mechanism of syncope, but those with positive TT had more frequently no or slight rhythm variations during spontaneous syncope (45 vs. 21%, P=0.02). An asystolic pause was more frequently found during spontaneous syncope than during TT (45 vs. 21%, P=0.02), but there was a trend for those with an asystolic response during TT also to have an asystolic response during spontaneous syncope (75 vs. 37%, P=0.1). Patients with positive ATP test responses showed syncopal recurrence rates and mechanism of syncope similar to those with negative ATP tests.

CONCLUSION

In patients with neurally mediated syncope, clinical characteristics, outcome, and mechanism of syncope are poorly correlated and not predicted by the results of TT and ATP test. Therefore, these tests are of little or no value in guiding specific therapy.

Head-up tilt testing for diagnosing vasovagal syncope: a meta-analysis

BACKGROUND

A systematic evaluation focused on sensitivity and specificity of head-up tilt testing (HUT) for diagnosing vasovagal syncope has not been previously performed. We conducted a meta-analysis of studies comparing HUT outcome between patients with syncope of unknown origin and control subjects without previous syncope.

METHODS

We searched Pubmed and Embase databases for all English-only articles concerning case-control studies estimating the diagnostic yield of HUT, and selected 55 articles, published before March 2012, including 4361 patients and 1791 controls. The influence of age, test duration, tilt angle, and nitroglycerine or isoproterenol stimulation on tilt testing outcome was analyzed.

RESULTS

Head-up tilt testing demonstrated to have a good overall ability to discriminate between symptomatic patients and asymptomatic controls with an area under the summary receiver-operating characteristics curve of 0.84 and an adjusted diagnostic odds ratio of 12.15 (p<0.001). A significant inverse relationship between sensitivity and specificity of tilt testing for each study was observed (p<0.001). At multivariate analysis, advancing age and a 60° tilt angle showed a significant effect in reducing sensitivity and increasing specificity of the test. Nitroglycerine significantly raised tilt testing sensitivity by maintaining a similar specificity in comparison to isoproterenol.

CONCLUSIONS

The results from this meta-analysis show the high overall performance of HUT for diagnosing vasovagal syncope. Our findings provide useful information for evaluating clinical and instrumental parameters together with pharmacological stressors influencing HUT accuracy. This could allow the drawing of tilt testing protocols tailored on the diagnostic needs of each patient with unexplained syncope.

Specificity of head-up tilt testing in adolescents: effect of various degrees of tilt challenge in normal control subjects

OBJECTIVES

This study sought to determine the specificity of commonly used tilt protocols in children.

BACKGROUND

Tilt table testing is commonly utilized in the evaluation of children and adolescents with syncope despite a lack of uniformity in tilt protocols and a lack of studies of specificity in normal control subjects.

METHODS

Sixty-nine normal control volunteers (12 to 18 years old, 38 male, 31 female) with no previous history of syncope, presyncope or arrhythmia underwent tilting to 80 degrees, 70 degrees or 60 degrees for a maximum of 30 min on a motorized table with a footboard support. Autonomic maneuvers, including deep breathing, carotid massage, Valsalva maneuver and diving reflex, were performed before tilt testing to determine whether the response to these maneuvers could identify subjects prone to fainting during tilt testing.

RESULTS

Symptoms of presyncope and frank syncope were elicited in 24 of 69 subjects (13 male, 11 female): 6 (60%) of 10 were tilted at 80 degrees, 9 (29%) of 31 at 70 degrees and 9 (32%) of 28 at 60 degrees. Tilt testing at 80 degrees was terminated after the tenth subject by the institutional review board. The mean time to a positive test response was 10.5 min at 80 degrees, 14.2 min at 70 degrees and 13.2 min at 60 degrees. In the 80 degrees tilt, 4 of 10 subjects had a positive response within 10 minutes, whereas only 3 of 31 and 2 of 28 had a positive response within < 10 min at 70 degrees and 60 degrees tilt angles, respectively. Subjects with and without a positive response to tilt testing were similar with respect to age; gender; PR, QRS and QT intervals; and baseline heart rate and blood pressure. Likewise, responses to other autonomic function tests performed were similar in tilt-positive and tilt-negative patients. The power for detecting a significant difference between patients tilted at 80 degrees versus 60 degrees and 70 degrees was 0.45 and for detecting differences in autonomic tone between tilt-positive (n = 24) and tilt-negative (n = 45) subjects was 0.8.

CONCLUSIONS

Children appear to be more susceptible to orthostatic stress than adults. Therefore, tilt protocols commonly used in adults lack specificity in teenage patients. A specificity > 85% may be obtained by performing the tilt test at 60 degrees or 70 degrees for no longer than 10 min.

'Front-loaded' head-up tilt table testing: validation of a rapid first line nitrate-provoked tilt protocol for the diagnosis of vasovagal syncope

Head-up tilt testing is the investigation of choice in the diagnosis of vasovagal syncope. The test is time consuming and labour intensive, with conventional tilt testing taking up to 45 min. We compared a shortened 'front-loaded' 20-min glyceryl trinitrate-provoked head-up tilt (FLGTN-HUT) with the standard 40-min passive tilt (HUT) as first line investigations in patients with unexplained syncope and asymptomatic controls. In the study, 149 consecutive patients with unexplained syncope and 83 asymptomatic controls were enrolled. Subjects were randomly assigned to FLGTN-HUT (800 mcg, metred spray) or HUT, then the opposite tilt-test 1 week later. Seventeen (11.4%) patients had diagnostic haemodynamic changes and symptom reproduction during HUT and 54 (36.2%) during FLGTN-HUT. A total of 24.8% more patients had a positive test with FLGTN-HUT than with passive HUT (95% CI: 16.3%, 33.4%). Nine (10.8%) controls had significant haemodynamic changes during HUT and 23 (27.7%) during GTN provocation. Seven controls had haemodynamic changes on both HUT and FLGTN-HUT testing. The controls group had 16.8% more significant haemodynamic changes with FLGTN-HUT than with HUT (95% CI: 0.06, 27.4). The front-loaded GTN protocol provided a higher diagnostic rate than passive tilt testing, and provides a rapid alternative to conventional methods, though false positivity rates are higher.

Responses to the prolonged head-up tilt followed by sublingual nitrate provocation in asymptomatic older adults

BACKGROUND

prolonged head-up tilt testing and sublingual nitrate provocation are increasingly used in the diagnosis of neurocardiogenic syncope. However there are few data regarding the results of these tests in asymptomatic older subjects.

OBJECTIVE

to assess the responses to the prolonged head-up tilt test followed by sublingual glyceryl trinitrate provocation in asymptomatic subjects over the age of 60 years.

DESIGN

observational study.

METHODS

we recruited 64 asymptomatic subjects over the age of 60 (39 men, 25 women) from two general practice lists in Nottingham and Leicester. Exclusion criteria were: history of syncope, ischaemic heart disease, cerebrovascular disease, marked aortic stenosis, carotid artery disease and being unable to stand for the duration of the test. All subjects underwent a full clinical examination, a 12-lead electrocardiogram and a 30-40-min head-up tilt test, during which we monitored the heart rate and blood pressure continuously. We ended the test prematurely if the subjects developed syncope or symptoms of presyncope associated with hypotension with or without bradycardia. If they remained asymptomatic at the end of this period, they received 400 microg of sublingual glyceryl trinitrate and monitoring continued for another 15 min.

SETTINGS

two teaching hospitals in Nottingham and Leicester.

RESULTS

six (9%) of the subjects had a positive response (syncope or presyncope) to the prolonged head-up tilt test prior to glyceryl trinitrate provocation. After provocation, 30 (52%) of the remaining 58 subjects had a positive response.

CONCLUSION

the role of sublingual glyceryl trinitrate provocation following prolonged head-up tilt testing in the diagnosis of neurocardiogenic (vasovagal) syncope in older people is questionable, as many asymptomatic older subjects demonstrate syncopal or presyncopal symptoms.

Cardiovascular dysautonomia of patients with end-stage renal disease and type I or type II diabetes

BACKGROUND

End-stage renal disease and diabetes mellitus are known to cause autonomic dysfunctions that are responsible for poor outcomes. Studies suggest that 24-hour heart rate variability with power spectral analysis is more sensitive to early changes in autonomic function than laboratory-evoked measures.

OBJECTIVES

To evaluate cardiovascular autonomic function in patients (a) awaiting kidney or pancreas-kidney transplantation, (b) without diabetes (NonDM), (c) with Type I insulin dependent diabetes mellitus (IDDM), and (d) with Type II noninsulin dependent diabetes mellitus (NIDDM), and to compare the results of the laboratory-evoked cardiovascular autonomic tests with those from 24-hour heart rate variability monitoring with power spectral analysis.

METHOD

This cross-sectional study examined autonomic function in prekidney transplant patients with and without diabetes (N=96), comparing laboratory-evoked measures to 24-hour measures.

RESULTS

The nondiabetic group had a normal change in heart rate with deep breathing, Valsalva ratio, and change in systolic blood pressure with tilt. Both diabetic groups had poorer values for all measures of heart rate variability; demonstrated abnormal changes in heart rate with deep breathing and borderline Valsalva ratios; demonstrated a greater decrease in circadian rhythmicity; and had lower SDNNS, pNN50s, and rMSSDs than the nondiabetic group.

CONCLUSIONS

Results showed that 24-hour measures are more sensitive, that patients with end-stage renal disease and diabetes regardless of type experience significantly poorer function than do patients without diabetes, and that these values approach those associated with sudden cardiac death.

Usefulness of clinical factors in predicting outcomes of passive tilt tests in patients with syncope

Pretest patient selection affects the outcome of many diagnostic tests; this may be true for tilt-table tests. We assessed the impact of patient age, sex, and symptom burden on the outcome of passive tilt tests. Two hundred one patients with idiopathic syncope (87 men, aged 45 +/- 20 years, median 5 fainting spells each) underwent passive, drug-free tilt tests for 45 minutes. Positive tests were defined as those ending in clinically reminiscent presyncope or syncope. Seventy-eight patients (39%) had a positive tilt test. Patients had a wide range of symptom burden, having a median 5 syncopal spells (interquartile range [IQR] 2.5 to 17.5) over a median 52.5 months (IQR 12 to 180) with a median frequency of 0.17 spells/month (IQR 0.042 to 0.67). None of these measures of symptom burden predicted tilt-test outcome (p = 0.33 to 0.46). In contrast, the age of the patient strongly predicted tilt-test outcome. The likelihood of a positive test was 75% in 36 patients < 25 years old and 31% in 165 patients > or = 25 years of age (p < 0.0001, chi-square for 2 x 5 table). Younger patients also fainted more quickly: patients < 25 years old fainted within 22 minutes of tilt and reached a clearly asymptotic value, whereas the likelihood of a positive tilt in patients > or = 25 years old increased linearly with time, and did not reach an asymptote. Measures of symptom burden do not predict test outcome, and younger patients are more likely to faint during passive tilt testing.

Can stroke volume and cardiac output be determined reliably in a tilt-table test using the pulse contour method?

The applicability of the finger pressure-derived pulse contour (PC) technique was evaluated in the measurement of stroke volume (SV), cardiac output (CO) and their changes in different phases of the tilt-table test. The reference method was whole-body impedance cardiography (ICG). A total number of 40 physically active patients, aged 41 +/- 19 years, were randomly chosen from a pool of 230. Specifically speaking, 20 of the patients experienced (pre)syncope (tilt+ patients) during the head-up tilt (HUT), and 20 did not (tilt-). A total number of three measurement periods, 30-60 s each, were analysed: supine position, 5 min after the commencement of HUT, and 1 min before set down. SV and CO values measured by PC underestimated significantly those measured by ICG (biases +/- SD 19 +/- 14 ml and 1.55 +/- 1.14 l min-1, respectively) in agreement with earlier reports. The bias between the methods was almost the same in the different phases of the test. However, the SD of the bias was bigger for tilt+ (P < 0.05). When the bias between the methods was eliminated by scaling the first measurement to 100%, the agreement between the methods in the second and third measurements was clearly better than without scaling. Both methods showed a physiological drop in SV after the commencement of HUT. These results indicate that PC suffices in tracking the changes in CO and SV, but for absolute values it is not reliable.

Formal analysis of the optimal duration of tilt testing for the diagnosis of neurally mediated syncope

BACKGROUND

Although tilt testing has emerged as the test of choice for assessing patients with suspected neurally mediated syncope, the optimum duration of tilt testing is poorly defined. This in part relates to the absence of a gold standard to assess test performance.

OBJECTIVE

Our purpose was to formally estimate the effects of varying duration of drug-free tilt testing on test performance in diagnosing neurally mediated syncope.

DESIGN

If a test's specificity is known, then in the absence of a gold standard an imputed (estimated) sensitivity may be calculated on the basis of the observed diagnostic yield in a given population as a function of assumed population prevalence. We determined the relationship of specificity to drug-free tilt test duration by use of data from 11 previous studies reporting the results of drug-free tilt testing in a total of 435 control subjects (60 to 80 degrees of tilt, footboard support, 15- to 60-minute duration). Data (weighted for study size) were fit to an exponential function relating specificity to tilt duration. Test yield was evaluated as a function of tilt duration in 213 consecutive patients referred to our laboratory for the evaluation of suspected neurally mediated syncope who underwent passive tilt testing for up to 30 to 60 minutes.

RESULTS

The estimated specificity of tilt testing was 94% at 30 minutes, 92% at 40 minutes, and 88% after 60 minutes of passive tilt. The cumulative yield of tilt testing was only 17% at 30 minutes, 22% at 40 minutes, and 28% after 60 minutes. On the basis of an estimated population prevalence of 25% to 50% in this referral population, imputed sensitivity is 27% to 48% at 30 minutes, 36% to 64% at 40 minutes, and 43% to 74% after 60 minutes of passive tilt. The overall diagnostic accuracy was not strongly influenced by tilt duration beyond 30 minutes and ranged from 60% to 84%.

CONCLUSIONS

Passive tilt testing (ie, tilt testing without pharmacologic provocation) for durations of up to 60 minutes has limited sensitivity for diagnosing neurally mediated syncope. For populations with a pretest likelihood of 25% to 50%, test results are inaccurate in one to two fifths of patients.

Test-retest reliability and four-week changes in cardiopulmonary fitness in stroke patients: evaluation using a robotics-assisted tilt table

BACKGROUND

Exercise testing devices for evaluating cardiopulmonary fitness in patients with severe disability after stroke are lacking, but we have adapted a robotics-assisted tilt table (RATT) for cardiopulmonary exercise testing (CPET). Using the RATT in a sample of patients after stroke, this study aimed to investigate test-retest reliability and repeatability of CPET and to prospectively investigate changes in cardiopulmonary outcomes over a period of four weeks.

METHODS

Stroke patients with all degrees of disability underwent 3 separate CPET sessions: 2 tests at baseline (TB1 and TB2) and 1 test at follow up (TF). TB1 and TB2 were at least 24 h apart. TB2 and TF were 4 weeks apart. A RATT equipped with force sensors in the thigh cuffs, a work rate estimation algorithm and a real-time visual feedback system was used to guide the patients' exercise work rate during CPET. Test-retest reliability and repeatability of CPET variables were analysed using paired t-tests, the intraclass correlation coefficient (ICC), the coefficient of variation (CoV), and Bland and Altman limits of agreement. Changes in cardiopulmonary fitness during four weeks were analysed using paired t-tests.

RESULTS

Seventeen sub-acute and chronic stroke patients (age 62.7 ± 10.4 years [mean ± SD]; 8 females) completed the test sessions. The median time post stroke was 350 days. There were 4 severely disabled, 1 moderately disabled and 12 mildly disabled patients. For test-retest, there were no statistically significant differences between TB1 and TB2 for most CPET variables. Peak oxygen uptake, peak heart rate, peak work rate and oxygen uptake at the ventilatory anaerobic threshold (VAT) and respiratory compensation point (RCP) showed good to excellent test-retest reliability (ICC 0.65-0.94). For all CPET variables, CoV was 4.1-14.5 %. The mean difference was close to zero in most of the CPET variables. There were no significant changes in most cardiopulmonary performance parameters during the 4-week period (TB2 vs TF).

CONCLUSIONS

These findings provide the first evidence of test-retest reliability and repeatability of the principal CPET variables using the novel RATT system and testing methodology, and high success rates in identification of VAT and RCP: good to excellent test-retest reliability and repeatability were found for all submaximal and maximal CPET variables. Reliability and repeatability of the main CPET parameters in stroke patients on the RATT were comparable to previous findings in stroke patients using standard exercise testing devices. The RATT has potential to be used as an alternative exercise testing device in patients who have limitations for use of standard exercise testing devices.

Mechanisms of tilt-induced vasovagal syncope in healthy volunteers and postural tachycardia syndrome patients without past history of syncope

Upright tilt table testing has been used to test for vasovagal syncope (VVS) but can result in "false positives" in which tilt-induced fainting (tilt+) occurs in the absence of real-world fainting. Tilt+ occurs in healthy volunteers and in patients with postural tachycardia syndrome (POTS) and show enhanced susceptibility to orthostatic hypotension. We hypothesized that the mechanisms for hypotensive susceptibility differs between tilt+ healthy volunteers (Control-Faint (N = 12)), tilt+ POTS patients (POTS-Faint (N = 12)) and a non-fainter control group of (Control-noFaint) (N = 10). Subjects were studied supine and during 70° upright tilt while blood pressure (BP), cardiac output (CO), and systemic vascular resistance (SVR), were measured continuously. Impedance plethysmography estimated regional blood volumes, flows, and vascular resistance. Heart rate was increased while central blood volume was decreased in both Faint groups. CO increased in Control-Faint because of reduced splanchnic vascular resistance; splanchnic pooling was similar to Control-noFaint. Splanchnic blood flow in POTS-Faint decreased and resistance increased similar to Control-noFaint but splanchnic blood volume was markedly increased. Decreased SVR and splanchnic arterial vasoconstriction is the mechanism for faint in Control-Faint. Decreased CO caused by enhanced splanchnic pooling is the mechanism for faint in POTS-Faint. We propose that intrahepatic resistance is increased in POTS-Faint resulting in pooling and that both intrahepatic resistance and splanchnic arterial vasoconstriction are reduced in Control-Faint resulting in increased splanchnic blood flow and reduced splanchnic resistance.

Development of a new method for assessing the cardiac baroreflex: response to downward tilting in patients with diabetes mellitus

OBJECTIVE

To investigate the clinical value of a new non-invasive method for assessing baroreflex sensitivity using downward tilting.

PATIENTS

34 patients with diabetes mellitus, mean (SD) age, 53.6 (11.8) years.

DESIGN

Arterial blood pressure and ECG were recorded simultaneously while the patients were on a tilt table. After 20 minutes at a 70 degrees upright tilt, the patients were returned to the supine position at a speed of 3.2 degrees /s (downward tilting baroreflex sensitivity test, DT-BRS). A beat to beat systolic blood pressure increase associated with a corresponding lengthening of the RR interval was noted during downward tilting. Baroreflex sensitivity was also assessed using the conventional method of an intravenous injection of phenylephrine (Phe-BRS). Heart rate variability was analysed during rest and tilting.

RESULTS

The slope of the regression line for systolic blood pressure v RR interval during downward tilting was highly correlated with Phe-BRS (r = 0.83, p < 0.0001). Both DT-BRS and Phe-BRS were correlated with the high frequency (HF) component of resting heart rate variability (p < 0.005) and with the ratio of the low frequency to the high frequency component (LF/HF) during upright tilting (p < 0.005). DT-BRS and Phe-BRS were also correlated with the difference between rest and tilting values of HF and LF/HF (p < 0.005).

CONCLUSIONS

DT-BRS provides a physiological, non-invasive method for determining baroreflex sensitivity and may be a useful index of reflex cardiac vagal and sympathetic function in patients with diabetes mellitus.

Specificity and total positive rate of head-up tilt testing potentiated with sublingual nitroglycerin in older patients with unexplained syncope

The aim of this study was to assess the specificity and total positive rate of head-up tilt testing (HUTT) potentiated with sublingual nitroglycerin in detecting the vasovagal origin of unexplained syncope in the elderly, since the diagnostic value of this non-invasive test has not yet been proven in this age group. In a period of 3 years, 128 elderly patients (mean age 71.6+/-5.1 years, 50% males) with syncope of unknown origin, and 101 control subjects matched for age and gender were tilted upright to 60 degrees for 45 minutes. If syncope did not occur, sublingual nitroglycerin (0.4 mg) was administered, and observation was continued for 20 minutes. The positive response was defined as the reproduction of syncope or pre-syncope according to VASIS definition. During the unmedicated phase, syncope occurred in 26 patients (20.3%) and in no members of the control group. After nitroglycerin, 53 patients (41.4%) and 2 control subjects (2%) displayed syncope. The total positive rate of the test was 61.8% with a specificity of 98.0%. In conclusion, HUTT potentiated with sublingual nitroglycerin provides an adequate specificity and total positive rate in old patients with unexplained syncope; therefore it can be proposed as a useful diagnostic tool to detect the vasovagal origin of syncope not only in middle but also in advanced age.

[Role of tilt test in the diagnostic and therapeutic management of syncopes]

Following confirmation of one or several episodes of syncope, the most important step is identification of the cause. Unfortunately, despite a careful actiological work-up, a cause is not found in about 30 to 40% of cases, but the tilt test can attribute some of these cases to a vagal cause. The test must be performed according to a rigorous methodology and interpretation must be based on a good knowledge of abnormalities of the autonomic nervous system, particularly the pathophysiology of vagal syncope. The tilt-test can also be useful to evaluate the efficacy of drug treatment prescribed to prevent recurrent syncope.

Can standing replace upright tilt table testing in the diagnosis of postural tachycardia syndrome (POTS) in the young?

PURPOSE

We compared standing and upright tilt in patients with postural tachycardia syndrome (POTS) and healthy volunteers to determine whether standing accurately tests for POTS in youngsters < 19 years. POTS in adolescents is defined by orthostatic intolerance plus sustained excessive upright tachycardia, without hypotension during upright tilt. We examined whether active standing is a valid classifier for POTS in adolescents compared to tilt.

METHODS

Patients with POTS (N = 36, 12.2-18.8 years) and healthy volunteers (N = 39, 13.1-18.9 years) performed stand for a minimum of 5-min and were tilted to 70° for 10 min. Receiver operating characteristics analyses (ROC) were performed at 5-min stand, and at 5  and 10 min tilt for optimal threshold for heart rate (HR) increase (ΔHR), and test sensitivity and specificity.

RESULTS

Most subjects were unable to stand for 10 min. ΔHRs at 5 min stand were higher in POTS (31 ± 3) compared with control (21 ± 2) and elevated at 5- or 10-min tilt in POTS (51 ± 3 and 51 ± 2) versus control (26 ± 2 and 25 ± 2) compared with standing. ΔHR in POTS and controls for 10 min were not different from 5 min. For 5 min stand ROC threshold was 26 beats per min (bpm), sensitivity of 70.6%, and specificity of 68.2% compared with 39 bpm, 88.2%, and 95.1% for 5 min tilt, and 40 bpm, 94.1%, and 95.1% for 10-min tilt. A precision-recall graph confirmed the superior discriminating ability of 5 min and 10 min tilt compared to 5 min stand.

CONCLUSIONS

The stand test is relatively non-specific and imprecise compared to tilt and does not satisfactorily distinguish POTS from control in patients aged < 19 years old.

Diagnostic efficacy of transcranial Doppler combined with upright tilt test in vasovagal syncope

BACKGROUND

Vasovagal syncope (VVS) is the most common subtype of syncope, and it significantly impacts patients' quality of life and incurs substantial healthcare costs. Although the head-up tilt table test (HUTT) is the gold standard method for diagnosing VVS, its sensitivity and specificity are limited, which leads to diagnostic challenges. Combining HUTT with transcranial Doppler (TCD) can improve diagnostic accuracy by addressing limitations in monitoring cerebral blood flow during syncope evaluation. In this study, we aimed to analyze the diagnostic efficacy of combining the HUTT and TCD in patients with VVS.

METHODS

In this prospective study, we enrolled 102 patients with suspected VVS who underwent combined HUTT and TCD evaluation. The diagnostic performance of the combined approach was compared to that of the standalone HUTT, with a focus on sensitivity, specificity, and accuracy.

RESULTS

The multimodal testing group showed a 25.61% increase in sensitivity for diagnosing VVS compared to the standalone HUTT group, albeit with a 10.00% reduction in specificity. The false-negative rate decreased by 25.61%, while the false-positive rate increased by 10.00%. Furthermore, the positive likelihood ratio increased by 0.151, and the negative likelihood ratio decreased by 0.3701. The overall accuracy increased by 7.8%. Notably, the areas under the curve for systolic and mean cerebral blood flow velocities were 0.717 and 0.744, respectively.

CONCLUSIONS

The combination of HUTT and TCD significantly enhanced the diagnostic efficacy in patients with VVS, improving the prediction of syncope and reducing the risks associated with testing.

[Estimation of head-up tilt test in diagnosis of syncope of unknown origin. Can we come up with better results?]

Optimal conditions in assessment of diagnostic head-up tilt test (TT) value required classification, which identified reactions with syncope and discreet disturbance of consciousness. The aim of the study was to assess of usefulness TT in diagnosis of syncope of unknown origin investigated by classification, which take into consideration vasovagal and nonvasovagal types of neurocardiogenic reactions. We studied 218 pts (115M, 103F), mean age 39.7 +/- 16.1 and 35.2 +/- 17.7 years (adequately for male and female), with 2 or more syncope on unknown origin in last 6 months. Control group was 84 healthy volunteers (43M, 41F), mean age 37.41 +/- 2.6 years, range 18 to 73 years, with no syncope in anamnesis. All patients and controls underwent a TT in Westminster protocol. In case of negative TT, we performed next 20 min TT with 0.25 mg NTG sublinqualis (TT with NTG). Type of vasovagal syncope was defined according to American Experts Classification described in official guidelines of American College of Cardiology (ACC). In the case of vasovagal syncope, detailed specification of syncope was performed according to VASIS classification (the vasovagal Syncope International Study). Passive TT was positive in 51 (23%) pts. In control group passive TT was positive in 6 (7%) pts. TT with NTG generates syncope in additional 99 (45%) pts resulting in number of diagnosed group to 150 (68%) pts. In control group TT with NTG was positive in additional 21 (25%) pts. False positive TT with NTG was diagnosed in 19 (9%) pts in study group and 11 (13%) in control group. Subpopulation of study group with vasovagal syncope was larger than subpopulation with other, nonvasovagal type of reaction (108 vs. 23; p < 0.0001). Taking into consideration this dual types of reaction (vaso- and nonvasovagal) allowed to reveal that there were no statistical significance between sex, age, type of syncope provocation and defined types of vasovagal reactions. ACC classification in comparison to VASIS criteria, was more sensitive (60% vs. 49%), have better diagnostic value to positive (89% vs. 84%) and negative (44% vs. 39%) result of TT and accuracy of diagnosis (66% vs. 47%) with slightly worse specificity of TT (81% vs. 83%).

CONCLUSIONS

1. TT results assessment according to ACC classification is more sensitive and almost the same specificity method in diagnosing patients with syncope of unknown origin than VASIS classification. 2. Improvement in diagnostic values of TT concerns passive TT and NTG TT. 3. Nonvasovagal types of reaction of cardiovascular system to orthostatic stress defined in ACC classification are, as the symptomatically syncope, significant clinical indicator of vegetative system instability.

Evaluating tilt table testing in syncope 2: management options

This is a two-part unit on syncope and the value of tilt table testing. Part 1 discussed the physiology of syncope, the procedure of tilt table testing, and indications and contraindications for it. This second part outlines the four common non-cardiac causes of syncope, treatment and management options.

The fainting patient: value of the head-upright tilt-table test in adult patients with orthostatic intolerance

The head-upright tilt-table (HUT) test is used primarily for the investigation of orthostatic symptoms. Although this test is frequently the gold standard for the evaluation of neurocardiogenic syncope, dysautonomia and postural orthostatic tachycardia syndrome, there is a debate over its diagnostic value and method. The authors review the physiologic basis of the HUT test, the method, patterns of response, indications and contraindications, and diagnostic validity. Despite its limitations, the HUT test is useful in patients with a variety of clinical manifestations induced by orthostatism. It is most useful in documenting objective measures of orthostatic hypertension that cannot be obtained in a clinical setting.

Tilt testing for syncope: a reappraisal

PURPOSE OF REVIEW

Tilt-table tests have provided a diagnostic window on the most common cause of syncope, the common faint. The purpose of this review is to summarize the major contributions of tilt tests and provide a critical assessment of the true validity and usefulness of this diagnostic test.

RECENT FINDINGS

Tilt-table tests have provided mixed benefits in the field of neurally mediated syncope. They have greatly improved informed care of syncope patients and have led to a revived interest in the field. They have provided study populations having at least one objective finding in common for diagnostic studies, long-term observational studies, and randomized clinical trials. Tilt tests have been used as platforms for physiologic studies and pilot treatment studies. However, more specific benefits have proven illusive. The main problem is that the neurally mediated syncope syndrome is defined by the test, rather than by evidence-based and widely accepted clinical criteria. Tilt tests have a complex mix of significant methodological variables, have not been validated against gold standard populations, are only moderately reproducible, do not provide prognostic predictive power, and have not been shown useful in selecting efficacious therapies. It may be difficult to achieve important advances in the field until a clinical reflex syncope syndrome is defined by evidence-based diagnostic criteria.

SUMMARY

Tilt tests have made neurally mediated syncope amenable to clinical study, but their true usefulness will only be known when an evidence-based, widely accepted definition of this syndrome is developed.