Methods other than tilt testing for diagnosing neurocardiogenic (neurally mediated) syncope

Carotid Sinus Massage in Syncope Evaluation: A Nonspecific and Dubious Diagnostic Method

BACKGROUND

Carotid sinus hypersensitivity (CSH) is a frequent finding in the evaluation of syncope. However, its significance in the clinical setting is still dubious. A new criterion was proposed by Solari et al. with a symptomatic systolic blood pressure (SBP) cut-off value of ≤ 85 mmHg to refine the vasodepressor (VD) response diagnosis.

OBJECTIVE

To determine and compare the response to carotid sinus massage (CSM) in patients with and without syncope according to standard and proposed criteria.

METHODS

CSM was performed in 99 patients with and 66 patients without syncope. CSH was defined as cardioinhibitory (CI) for asystole ≥ 3 seconds, or as VD for SBP decrease ≥ 50 mmHg.

RESULTS

No differences in the hemodynamic responses were observed during CSM between the groups, with 24.2% and 25.8% CI, and 8.1% and 13.6% VD in the symptomatic and asymptomatic groups, respectively (p = 0.466). A p value < 0.050 was considered statistically significant. During the maneuvers, 45 (45.45%) and 34 (51.5%) patients in the symptomatic and asymptomatic groups achieved SBP below ≤ 85 mmHg. Symptoms were reported especially in those patients in whom CSM caused a SBP decrease to below 90 mmHg and/or asystole > 2.5 seconds, regardless of the pattern of response or the presence of previous syncope.

CONCLUSION

The response to CSM in patients with and without syncope was similar; therefore, CSH may be an unspecific condition. Clinical correlation and other methods of evaluation, such as long-lasting ECG monitoring, may be necessary to confirm CSH as the cause of syncope.

Metabolische Störungen

Im folgenden Kapitel werden die verschiedenen metabolischen Störungen betrachtet. Zunächst wird auf die allgemeinen und spezifischen neurologischen Komplikationen bei Organtransplantation eingegangen. Dann geht es um die metabolischen Enzephalopathien: Störungen der Gehirntätigkeit bei angeborenen und erworbenen Stoffwechselerkrankungen im engeren Sinn, Elektrolytstörungen, Hypovitaminosen, zerebrale Folgen einzelner Organdysfunktionen, zerebrale Hypoxien, Endotheliopathien und Mitochondropathien. Anschließend werden das Alkoholdelir und die Wernicke-Enzephalopathie erörtert. Bei zahlreichen akuten Erkrankungen von Gehirn, Rückenmark und peripherem Nervensystem treten typische Störungen vegetativer Systeme auf, deren Erkennung und Therapie insbesondere bei Intensivpatienten eine vitale Bedeutung haben kann: die autonomen Störungen. Bei der zentralen pontinen Myelinolyse kommt es zu einer akuten, vorwiegend fokal-symmetrischen Demyelinisierung im Hirnparenchym. Auch Basalganglienerkrankungen können intensivmedizinisch relevant werden. Und schließlich wird die akute Stressreaktion betrachtet, die aufgrund der vielfältigen metabolischen und endokrinen Veränderungen bei kritischen Erkrankungen entsteht. Gerade das RCVS als neuere Krankheitsentität und wichtige Differenzialdiagnose zur Vaskulitis des ZNS verdient einen eigenen Platz, in diesem Unterkapitel werden ebenfalls verwandte Syndrome wie die hypertensive Enzephalopathie und das PRES abgehandelt.

Paroxysmal atrioventricular block in young patients

We describe 17 patients (8 girls, and 9 boys), aged 9.6 +/- 5.7 years, with paroxysmal atrioventricular block (PAVB), a condition rarely described in children. Holter monitoring documented the PAVB in 15 patients, and tilt test was performed in 4 patients (positive in 1). The electrocardiograph (ECG) was normal in 7 patients. Two patients had acquired and 11 patients had congenital heart disease (CHD). Syncope or presyncope were present in 7 patients. A normal ECG was significantly more frequent in symptomatic patients. Pauses were significantly longer in girls and in children <5 years. PAVB was recorded only during nocturnal hours in 6 patients and throughout the day in the others. The sinus rate decreased during PAVB in 6 patients and increased in 4 (generally younger girls with symptoms). Permanent pacemakers were implanted in 13 patients, including 7 asymptomatic patients with CHD and severe bradycardia. During follow-up (3.7 +/- 2.5 years), 1 patient developed complete AVB. Although PAVB was still present in 91% of paced patients, symptoms did not recur because pacing prevented the pauses. In conclusion, PAVB is a rare arrhythmia. Autonomic nervous system dysfunction seems to play an etiological role and permanent pacing was an effective treatment.

[Value and limitations of carotid sinus massage in healthy elderly individuals. Evaluation of diagnostic criteria for hypersensitive carotid sinus syndrome]

OBJECTIVE

To study the value and limitations of carotid sinus massage in healthy individuals older then 50 years of age, in order to assess the validity of the widely used criteria for the diagnosis of hypersensitive carotid sinus syndrome.

METHODS

Right and left carotid sinus massage was performed in 120 healthy individuals older then 50 years of age (74 males and 46 females aged 59 +/- 7 years) who had no prior history of syncope, pre-syncope, or abnormal bradyarrhythmia, during EKG monitoring.

RESULTS

Hypersensitivity of the carotid sinus (HSCS) defined as a pause > 3 s, was found in 28 individuals (23.3%). The pause was induced by right carotid sinus massage in 20 cases and by left carotid sinus massage in 8 cases. Patients demonstrating HSCS were older compared to those who did not develop a pause. One or multiple blocked P wave was seen in 16 cases when carotid sinus massage was performed on the left side compared to 8 with right carotid sinus massage.

CONCLUSION

In healthy individuals older than 50 years of age, it is not rare to induce a significant pause following carotid sinus massage. This limits the validity of the widely used criteria for the diagnosis of hypersensitive carotid sinus syndrome. Additional criteria are proposed to make this diagnosis in front of a brief loss of consciousness.

Dual-chamber pacing in the treatment of neurally mediated tilt-positive cardioinhibitory syncope : pacemaker versus no therapy: a multicenter randomized study. The Vasovagal Syncope International Study (VASIS) Investigators

BACKGROUND-This study was performed to compare implantation of a DDI pacemaker with rate hysteresis with no implant in respect to syncopal recurrences in patients with severe cardioinhibitory tilt-positive neurally mediated syncope. METHODS AND RESULTS-Forty-two patients from 18 European centers were randomized to receive a DDI pacemaker programmed to 80 bpm with hysteresis of 45 bpm (19 patients) or no pacemaker (23 patients). Inclusion criteria were >/=3 syncopes over the last 2 years and a positive cardioinhibitory (Vasovagal Syncope International Study types 2A and 2B) response to tilt testing. The median number of previous syncopal episodes was 6; asystolic response to tilt testing was present in 36 patients (86%) (mean asystole, 13.9+/-10.2 seconds). All patients were followed up for a minimum of 1.0 years and a maximum of 6.7 years (mean, 3.7+/-2.2). One patient (5%) in the pacemaker arm experienced recurrence of syncope compared with 14 patients (61%) in the no-pacemaker arm (P=0.0006). In the no-pacemaker arm, the median time to first syncopal recurrence was 5 months, with a rate of 0.44 per year. On repeated tilt testing performed within 15 days after enrollment, positive responses were observed in 59% of patients with pacemakers and in 61% of patients without pacemakers (P=NS). CONCLUSIONS-In a limited, select group of patients with tilt-positive cardioinhibitory syncope, DDI pacing with hysteresis reduced the likelihood of syncope. The benefit of the therapy was maintained over the long term. Even in untreated patients, the syncopal recurrence burden was low. A negative result of tilt testing was not a useful means to evaluate therapy efficacy.

Spontaneous paroxysmal atrioventricular block in patients with positive tilt tests and negative electrophysiologic studies

A subgroup of patients with neurocardiogenic syncope and negative electrophysiologic studies and adenosine tests (in 5 of 6 cases), who developed symptomatic paroxysmal atrioventricular block in the natural, ambulatory state, had positive tilt tests without advanced block. Lack of concordance between electrocardiographic changes may have reflected differential effects of the autonomic nervous system in the sinus and atrioventricular nodes, occurring in diverse circumstances and less likely because of the protocol used for tilt testing.

Reproducibility of the adenosine-5'-triphosphate test in vasovagal syndrome

INTRODUCTION

Adenosine-5'-triphosphate (ATP) provokes negative chronotropic and dromotropic vagal effects. In vasovagal syndrome, ATP test (20-mg i.v. bolus infusion) represents a promising technique for identifying patients at risk of severe cardioinhibitory response of vagal origin. The electrocardiographic and related symptom reproducibility of this descriptive test must be assessed.

METHODS AND RESULTS

In order to achieve this objective, ATP tests were performed twice in 80 patients (44 men, 36 women; mean age 72.3+/-12.2 years) by using the recently published test procedure and criteria of positivity. The second test was repeated shortly after the initial test (mean: 7 days) in 43 patients and long-term (mean: 3.7 years) in 37 patients. The initial ATP test provoked a cardiac pause > 10 seconds in 31 patients (39%) and a short cardiac pause (< or =10 sec) or no pause in 49 patients (61%). The electrocardiographic outcome was reproduced during the second ATP test in 36 patients (84%) of the short-term group and in 29 patients (78%) of the long-term group. Similarly, symptoms were reproduced in 38 patients (88%) of the short-term group and 29 patients (78%) of the long-term group, reflecting the severity of the electrocardiographic outcome.

CONCLUSION

The negative chronotropic and dromotropic vagal effect of ATP can be reproduced short term and long term in 84% and 78% of patients, respectively. Associated symptoms were related to the severity of the electrocardiographic outcome.

Variable cerebral dysfunction during tilt induced vasovagal syncope

Electroencephalographic (EEG) monitoring was performed during head-up tilt testing (HUT) in a group of 63 consecutive patients (27 males, 36 females, mean age 41.5 years) with a history of recurrent syncope of unknown origin despite extensive clinical and laboratory evaluation. Syncope occurred in 27/63 patients (42.8%) during HUT and was cardioinhibitory in 11/27 (40.7%) and vasodepressor in 16/27 (59.3%). All patients with a negative response to HUT had no significant EEG modifications. In patients with vasodepressor syncope a generalized high amplitude 4-5 Hz (theta range) slowing of EEG activity appeared at the onset of syncope, followed by an increase in brain wave amplitude with a reduction of frequency at 1.5-3 Hz (delta range). The return to the supine position was associated with brain wave amplitude reduction and frequency increase to 4-5 Hz, followed by restoration of a normal EEG pattern and arousal (mean total duration of syncope 23.2 s). In patients with cardioinhibitory syncope, a generalized high amplitude EEG slowing in the theta range was noted at the onset of syncope, followed by a brain wave amplitude increase and slowing in the delta range. A sudden reduction of brain wave amplitude ensued leading to the disappearance of electroencephalographic activity ("flat" EEG). The return to the supine position was not followed by immediate resolution of EEG abnormalities or consciousness recovery, both occurring after a longer time interval (mean total duration of syncope 41.4 s). EEG monitoring during HUT allowed the recording and systematic description of electroencephalographic abnormalities developing in the course of tilt induced vasovagal syncope.

Electroencephalographic correlates of vasovagal syncope induced by head-up tilt testing

BACKGROUND AND PURPOSE

We sought to determine whether the introduction of EEG monitoring during head-up tilt testing could significantly improve the understanding of the cerebral events occurring during tilt-induced vasovagal syncope and the potential danger to the patient of this diagnostic procedure.

METHODS

EEG monitoring was performed during head-up tilt testing in a group of 63 consecutive patients (27 males and 36 females; mean age, 41.5 years) with a history of recurrent syncope of unknown origin despite extensive clinical and laboratory assessment.

RESULTS

Syncope occurred in 27 of 63 patients (42.8%) during head-up tilt testing and was found to be cardioinhibitory in 11 of 27 (40.7%) and vasodepressor in 16 of 27 (59.3%). All patients with a negative response to head-up tilt testing showed no significant EEG modifications. In patients with vasodepressor syncope, a generalized high-amplitude, 4- to 5-Hz (theta range) slowing of EEG activity appeared at the onset of syncope, followed by an increase of brain-wave amplitude with the reduction of frequency at 1.5 to 3 Hz (delta range). The return to the supine position was associated with brain-wave amplitude reduction and frequency increase to 4 to 5 Hz, followed by restoration of a normal EEG pattern and arousal (mean total duration of syncope, 23.2 seconds.). In patients with cardioinhibitory syncope, a generalized high-amplitude EEG slowing in the theta range was noted at the onset of syncope, followed by a brain-wave amplitude increase and slowing in the delta range. A sudden reduction of brain-wave amplitude then ensued, leading to the disappearance of electrocerebral activity ("flat" EEG). The return to the supine position did not allow either the immediate resolution of EEG abnormalities or consciousness recovery, both of which occurred after a further time interval (mean total duration of syncope, 41.4 seconds.).

CONCLUSIONS

EEG monitoring during head-up tilt testing allowed recording and systematic description of electrocerebral abnormalities developing in the course of tilt-induced vasovagal syncope.

Sudden Wenckebach periods and their relationship to neurocardiogenic syncope

Throughout a 9-month period during which 1,125 Holter tapes were reviewed prospectively we identified 13 nonmedicated patients with an arrhythmia, which for the purposes of this presentation was categorized, because of their mode of initiation, as sudden Wenckebach periods (WP). The episodes emerged abruptly from a normal (< or = 200 ms) PR interval with sudden prolongation of PR and PP intervals (and reversed PR-RP relationship) that took place over 1-8 cycles. The postpaced PR interval was shorter than that of the last conducted beat. The episodes were separated into two groups. Group I included 11 patients with symptoms other than syncope and Group II included 2 patients with syncope. There were 26 episodes of sudden WP in Group I. Twenty-five terminated in a single (and one in double) blocked P waves. Most episodes occurred between 10 PM and 7 AM. Symptoms did not correlate with the episodes. Mean 24-hour rates were < 90. In Group II there were 22 episodes, all occurring between 6 AM and 10 PM. The mean sinus cycle lengths before the phenomenon started to occur in Group I (861 +/- 185 ms) as well as the cycle lengths at the onset of block (1,096 +/- 215 ms) were statistically longer than those in Group II (591 +/- 40 ms and 747 +/- 63 ms, respectively, P < 0.0001). Although the mode of onset in the episodes in Group II was similar to Group I, 16 episodes terminated in 2-6 blocked P waves. Thus, the entire number of episodes could be categorized as an unusual type (because of the PR prolongation) of paroxysmal, or advanced second degree AV block. Because these patients had negative electrophysiological studies, positive tilt tests, and absent syncope after oral propranolol therapy, they were considered as having neurocardiogenic syncope. In addition, the faster than normal (> 100) mean 24-hour rates) suggested that they also had so-called inappropriate sinus tachycardia. In summary, Group I consisted of patients with a normal, benign, vagal-induced second-degree AV block, whereas the Holter findings in Group II appeared to reflect unusual (but natural, i.e., nonprovoked) electrocardiographic manifestations of certain patients with neurocardiogenic syncope.