A telemonitoring platform for the investigation of blood pressure profiles in pacemaker patients.

Rate responsive pacemakers (PM) use different strategies to adapt the patient paced rate, with the aim of having the best hemodynamic performance in response to internal or external conditions. Closed-loop stimulation (CLS) uses intracardiac impedance as a sensor principle. The evaluation of impact of different pacing modalities and technologies on the blood pressure (BP) profiles is mainly investigated in short-term laboratory settings, mainly due to the need of reliable daily-based BP values. The impact of CLS pacing on systemic blood pressure (BP) has been studied on short term basis, but data on long term effects are scarse. This study present a telemedicine platform designed for evaluating the effect of the rate responsive technology on daily systolic and diastolic BP data. BP and pacemaker data were collected daily from fourteen patients during a 3 month period. The total number of monitoring days was 1277 (91 day/patient), for a total number of 4455 BP measures. On average 3.5 measure/day/patient were received). The analysis of the BP data showed that CLS pacing results in diastolic pressure closer to the normal values than accelerometer-based pacing, which were associated to lower diastolic pressures.

[Performance indicators: INCA (cardiovascular indicators) project]. / Indicatori di performance: progetto INCA (INdicatori CArdiovascolari).

The objective of INCA project was the development and implementation of Acute Myocardial Infarction (AMI type ST elevation) process and outcome indicators for the regional cardiology units, testing the possibility of using regional healthcare information data to evaluate the quality of provided healthcare within the regional healthcare accreditation process. The project is introduced by an overview of major concepts of evaluating and managing quality of healthcare. We performed a literature review of structure, process and outcome indicators in cardiology and of accreditation standards for cardiology at national and international level. Through consensus procedures and according to international evidence based literature a set of 18 process and outcome indicators for AMI was defined. A specific procedure for data collection has been developed. Education and training of participants on procedures, quality and accreditation was achieved. Expected verifiable end-points have been achieved over a three months period of data collecting throughout 21 cardiology units, differentiated for level of complexity and location, for a total of 409 clinical observed cases of AMI. Analysis of data was followed by the diffusion of results. Successful data collection of clinical performance indicators on a regional basis was achieved. Participants have been trained to quality sciences. Results will be useful to evaluate and design implementation strategies of regional accreditation of health care services within a shared framework. Benchmarking within Regional hospital cardiology care services will be developed following self evaluation and continuous quality improvement cycle activities.

Analysis of rhythm variation during spontaneous cardioinhibitory neurally-mediated syncope. Implications for RDR pacing optimization: an ISSUE 2 substudy.

BACKGROUND: Little is known of the variations of the heart rate during spontaneous cardioinhibitory neurally-mediated syncope. Their knowledge has both academic and practical implications for the optimization of rate drop response (RDR) pacing mode. METHODS AND RESULTS: We describe variations of the rhythm occurring during 48 syncopal episodes documented by implantable loop recorder. The presyncopal phase of 18 s (interquartile range 9-65) was characterized by a fall in heart rate from 83 +/- 20 bpm to maximal bradycardia or (multiple) asystolic pauses which lasted a median of 19 s (10-30). The recovery phase lasted 22 s (7-52). The total duration of the cardioinhibitory reflex was 85 s (47-116). We then calculated the potential increase in benefit that an optimally programmed drop rate detection could provide compared with a reference Lower Rate detection. Compared with Lower Rate detection (defined as two consecutive beats at 40 bpm), drop rate detection (assumed to be drop size = 20 bpm, detection window = 1 min, and drop rate = 50 bpm) would have been able to introduce intervention pacing, a median of 5.7 s (interquartile range -5.1- -10.4) earlier in 28 cases (58%). CONCLUSION: Cardioinhibitory neurally-mediated reflex varies widely from a few seconds to some minutes. In our data the total duration was <2 min. Optimal RDR programming, being potentially able to anticipate the detection of the cardioinhibitory reflex by a few seconds, could provide an increase in benefit for cardiac pacing therapy in prevention of syncope.

Exercise-related syncope in young competitive athletes without evidence of structural heart disease. Clinical presentation and long-term outcome.

AIMS: Exercise-related syncopal spells in athletes receive great attention and are a source of anxiety in the sporting world. The aim of the present study is to describe the clinical presentation, the yield of the initial diagnostic work-up and the long-term outcome of a series of consecutive competitive athletes with recurrent exercise-related syncopal spells. METHODS AND RESULTS: The study cohort included 33 athletes (20 females, mean age 21.4+/-3.2 years) referred for recurrent unexplained episodes of exercise-related syncope (mean number of spells before evaluation 4.66+/-1.97). All athletes underwent an extensive evaluation, including echocardiography, 24-h electrocardiographic monitoring, exercise testing, cardiac electrophysiological study and head-up tilt testing. The echocardiographic examination revealed the presence of a mitral valve prolapse in two cases (6.0%). During maximal exercise testing, four athletes (12.1%) developed hypotension associated with pre-syncope. Twenty-two subjects (66.6%) showed a positive response to head-up tilt testing. During follow-up (33.5+/-17.2 months) 11/33 athletes (33.3%) showed at least one recurrence of exercise-related syncope (mean time to first recurrence 20.4+/-14.5 months). No other adverse event of any kind was noted during follow-up. The Kaplan-Meier estimates of first recurrence of exercise-related syncope after 12, 36 and 60 months were 9.1%, 24.4% and 42.9%. The number and frequency of exercise-related syncopal spells before evaluation were found to be univariate predictors of syncope recurrence (P<0.001). However, in the multivariate analysis, the number of exercise-related syncopal spells before evaluation was found to be the only independent predictor of syncope recurrence (P<0.05). CONCLUSIONS: These findings support the idea that recurrent exercise related-syncope is not associated with an adverse outcome in athletes without cardiac disease.

Permanent cardiac pacing versus medical treatment for the prevention of recurrent vasovagal syncope: a multicenter, randomized, controlled trial.

BACKGROUND: This clinical investigation was performed to compare the effects of permanent dual-chamber cardiac pacing with pharmacological therapy in patients with recurrent vasovagal syncope. METHODS AND RESULTS: Patients from 14 centers were randomized to receive either a DDD pacemaker provided with rate-drop response function or the beta-blocker atenolol at the dosage of 100 mg once a day. Inclusion criteria were age >35 years, >/=3 syncopal spells in the preceding 2 years, and positive response to tilt table testing with syncope occurring in association with relative bradycardia. The primary outcome was the first recurrence of syncope after randomization. Enrollment was started in December 1997, and the first formal interim analysis was performed on July 30, 2000. By that time, 93 patients (38 men and 55 women; mean age, 58.1+/-14.3 years) had been enrolled and randomized, although follow-up data were available for all patients (46 patients in the pacemaker arm, 47 patients in the pharmacological arm). The interim analysis showed a significant effect in favor of permanent cardiac pacing (recurrence of syncope in 2 patients [4.3%] after a median of 390 days) compared with medical treatment (recurrence of syncope in 12 patients [25.5%] after a median of 135 days; OR, 0.133; 95% CI, 0.028 to 0.632; P=0.004). Consequently, enrollment and follow-up were terminated. CONCLUSIONS: DDD pacing with rate-drop response function is more effective than beta-blockade for the prevention of syncopal recurrences in highly symptomatic vasovagal fainters with relative bradycardia during tilt-induced syncope.

Prevalence and correlates of syncope-related traumatic injuries in tilt-induced vasovagal syncope.

BACKGROUND: Vasovagal syncope represents the most common form of syncope in the general population and is usually considered as a benign affection. However, syncope-related traumatic injuries may represent a major complication of such a condition in a relevant percentage of cases. The aim of this study was to assess the prevalence and clinical correlates of syncope-related trauma in a cohort of consecutive patients with recurrent vasovagal syncope. METHODS: Three hundred and forty-six consecutive patients were studied in whom a diagnosis of vasovagal syncope was established. All subjects were interviewed with a standard questionnaire in order to collect all possible information about their clinical history and the occurrence of trauma during syncopal spells. RESULTS: Ninety-four of the 346 patients (27.2%) reported at least one syncope-related traumatic injury. In 31/346 cases (8.9%) the severity of trauma had determined hospital admission and surgical treatment. When compared to the rest of the study population, patients with syncope-related trauma showed a higher prevalence of male gender (p < 0.01), a higher absolute number (p < 0.01) and frequency (p < 0.01) of syncopal episodes in their history. Patients with trauma also reported a shorter duration of warning symptoms preceding syncope (p < 0.01), while showing a higher prevalence of positive cardioinhibitory response to tilt table testing (p < 0.01). Moreover, the number of syncope-related injuries was found to correlate significantly with the number of syncopal spells (r = 0.64, p < 0.01). CONCLUSIONS: Most practicing physicians consider vasovagal syncope as simply a benign affection in young people. However, such a clinical view should be partially revised, as recurrent vasovagal syncope is associated with significant trauma-related morbidity.

Diagnosing syncope in clinical practice. Implementation of a simplified diagnostic algorithm in a multicentre prospective trial - the OESIL 2 study (Osservatorio Epidemiologico della Sincope nel Lazio)

BACKGROUND: In some patients with syncope health care is inappropriate and ineffective. In a recent observational investigation in community hospitals of the Lazio region of Italy (the OESIL study) 54.4% of patients admitted with syncope from the emergency room were discharged without a conclusive diagnosis. AIM OF THE STUDY: A simplified two-step diagnostic algorithm was developed and prospectively implemented in nine community hospitals of the Lazio region of Italy in order to improve the diagnostic performance of clinicians, thereby reducing the number of undiagnosed patients. STUDY POPULATION: The study population included 195 consecutive patients (85 males and 110 females, mean age 62.5 years, range 13-95 years) presenting with a syncopal spell at the emergency room of one of the nine participating hospitals in a 2-month period. RESULTS: The systematic implementation of the proposed diagnostic algorithm resulted in a striking reduction of undiagnosed cases. The percentage of patients discharged without a conclusive diagnosis decreased from 54.4% to 17.5%. Neurally mediated syncope was diagnosed in 35.2% of cases, cardiac syncope in 20.9% and neurological syncope in 13.8%. CONCLUSIONS: The use of specific, simplified diagnostic guidelines and algorithms results in an improvement of overall clinical performance. However, the development of such decision-making aids should carefully consider the local circumstances of daily clinical practice.

Transoesophageal low-energy cardioversion of atrial fibrillation. Results with the oesophageal-right atrial lead configuration.

BACKGROUND: Low energy internal cardioversion is a safe and effective procedure to restore sinus rhythm in patients with atrial fibrillation refractory to external cardioversion. However the procedure is invasive and fluoroscopy is mandatory. Aim of the study To assess the efficacy, safety and tolerability of a new simplified procedure of low energy internal cardioversion. METHODS: Twenty-five consecutive patients (19 males and 6 females) with persistent atrial fibrillation were submitted to low energy internal cardioversion using a step-up protocol (in steps of 50 V, starting from 300 V). A large surface area lead (cathode) was positioned in the oesophagus, 45 cm from the nasal orifice. A second large surface area lead (anode) was positioned in the right atrium. A quadripolar lead was positioned at the right ventricular apex to achieve ventricular synchronization and back-up pacing. Oesophageal endoscopy was performed within 24 h of the end of the procedure and repeated after 48 h, if injury to the oesophageal mucosa had occurred. RESULTS: Sinus rhythm was restored in 23 patients (92%) with a mean delivered energy of 15.74 J (range 5-27) and a mean impedance of 48 Omega. In two patients, endoscopy revealed that small burns had occurred in the oesophageal mucosa. Such lesions spontaneously healed after 48 h. CONCLUSIONS: This new technique of performing low energy internal cardioversion is effective and safe and avoids the positioning of a lead in the coronary sinus or in the left pulmonary artery, thereby simplifying the procedure.

[The tilt test enhanced with oral nitroglycerin in patients with unexplained syncope: the Italian Protocol. The Working Group on Syncope of the Associazione Italiana di Aritmologia e Cardiostimolazione--the Arrhythmia Area of the Associazione Nazionale Medici Cardiologi Ospedalieri]. / Tilt test potenziato con nitroglicerina orale nei pazienti con sincope inspiegata: "Il Protocollo Italiano". Gruppo di Lavoro sulla Sincope AIAC--Area Aritmie ANMCO.

The head-up tilt testing potentiated with oral nitroglycerin, devised by an Italian group, is a simple, safe and powerful, but still not a standardized, diagnostic tool. In fact, owing to its rapid diffusion, the original protocol received, often arbitrarily, subsequent modifications. Thus a task force of experienced cardiologists defined the best methodology for the test on strictly evidence-based criteria. Particular attention was reserved to some controversial topics, such as the tilting angle, the duration of the passive and pharmacological stages of the test, the type and dosage of the drug utilized. We hope that the enclosed protocol, named by us as "The Italian Protocol", will be accepted as the standard methodology of the head-up tilt testing potentiated with oral nitrates.

'The Italian Protocol': a simplified head-up tilt testing potentiated with oral nitroglycerin to assess patients with unexplained syncope.

Head-up tilt testing potentiated by sublingual nitroglycerin (NTG), advocated by an Italian group, is a simple and safe but still not a standardized, diagnostic tool for the investigation of syncope. In fact, owing to its rapid spread, the original protocol received, often arbitrarily, many subsequent modifications. We now define the best methodology of the test on strictly evidence-based criteria as: stabilization phase of 5 min in the supine position; passive phase of 20 min at a tilt angle of 60 degrees; provocation phase of further 15 min after 400 micrograms NTG sublingual spray. Test interruption is made when the protocol is completed in the absence of symptoms, or there is occurrence of syncope, or occurrence of progressive (> 5 min) orthostatic hypotension. We intend that this protocol, named by us as 'The Italian Protocol', will be accepted as the standard methodology of the tilt test potentiated by sublingual nitrates.

The effect of atropine in vasovagal syncope induced by head-up tilt testing.

AIMS: This single-blinded, randomized, placebo-controlled study was designed and undertaken to assess the efficacy of intravenous atropine administration on haemodynamic impairment induced by head-up tilt testing in patients with vasovagal syncope. METHODS AND RESULTS: One hundred and thirteen consecutive patients (62 male and 51 female, mean age 46.3 years) with recurrent syncope, no evidence of cardiac, neurological or metabolic disease and a positive head-up tilt test were included in the study. Within 2 weeks of the first head-up tilt test all patients underwent a second tilt test. During this second test, all patients were randomized to receive a bolus of either atropine (0.02 mg. kg(-1)) or placebo (isotonic saline solution). The administration of atropine or placebo was performed at the onset of the haemodynamic modifications (heart rate and/or blood pressure fall) in conjunction with typical vasovagal prodromal symptoms. Treatment was taken as effective when symptoms aborted and the test was completed. In 29 of 113 patients the second tilt test was negative and these patients were excluded from final data analysis. Forty-one patients received placebo, which was effective in nine cases (21.9%). Atropine was administered to 43 patients and was effective in 30 cases (69.7%, P<0.01 vs placebo). The effects of treatment were analysed further to consider the haemodynamic patterns of tilt-induced vasovagal reflex. In the cardio-inhibitory form, placebo was never effective (15 cases), while atropine was effective in 15 of 18 cases (83.3%, P<0.001 vs placebo). In the vasodepressor form, placebo was effective in nine of 26 patients (34.6%), while atropine was effective in 15 of 25 cases (60.0%, no significant difference vs placebo). CONCLUSIONS: Atropine is fully effective in the cardio-inhibitory form of tilt-induced vasovagal reflex, but is limited in the vasodepressor form.

Single shock endocavitary low energy intracardiac cardioversion of chronic atrial fibrillation.

BACKGROUND: Discomfort related to low-energy internal cardioversion (LEIC) represents a real problem in patients (pts) with atrial fibrillation (AF). The aim of our study was to verify if a single shock could restore sinus rhythm (SR) with a lower discomfort for the pt. METHODS: Thirty pts with chronic AF were randomized to receive a single 350 V shock (15 pts) or multiple shocks of increasing energy (15 pts). Three leads were positioned, respectively, in the coronary sinus and in the lateral right wall for shock delivery, and in the right ventricular apex for R wave synchronization. Truncated, biphasic shocks were used. In the first group a single 350 V shock was directly delivered and a second 400 V shock was given only if SR has not been restored. In the second group, beginning at 50 volts the voltage was increased in steps of 50 volts until SR restoration. No patient was sedated. After each shock the pts were asked to rate their discomfort on a scale of 1 to 5 (1 = not perceived, 5 = severe discomfort). RESULTS: SR was restored in all the subjects. In group 1 SR was obtained in 12/15 (80%) pts with the first 350 V (8.1 +/- 0.8 joules) shock, while the remaining 3 patients required the second 400 V (10.2 +/- 0.3 joules) shock. In group 2 the mean atrial defibrillation threshold was 346.7 +/- 1029.7 volts (8.0 +/- 101.5 joules). Then discomfort score was 2.5 +/- 0.6 in group 1 and 3.3 +/- 10.6 in group 2 (p < 0.01). CONCLUSIONS: A single shock of 350 V restores SR in the majority of pts with chronic AF; by use this new approach, LEIC is tolerated better than the multiple shocks step-up protocol.

[The management of syncope in the hospital: the OESIL Study (Osservatorio Epidemiologico della Sincope nel Lazio)]. / Gestione della sincope in ospedale: lo Studio OESIL (Osservatorio Epidemiologico della Sincope nel Lazio).

BACKGROUND: While syncope is generally considered a frequent finding in clinical practice, no clear epidemiological evidence is available about the relevance of such an event in the general population of Italy. METHODS: The OESIL Study was designed and undertaken in 15 hospitals of the Italian region of Latium in order to assess the percentage of emergency-room visits and admissions due to syncope, as well as to analyze the in-hospital diagnostic work-up performed for this condition. RESULTS: During a two-month observation period, 781 (372 males and 409 females, mean age 55.2 (22.8 years) consecutive patients came to the emergency rooms of the 15 hospitals included in the investigation due to a syncope spell (0.9% of emergency room visits); 450/781 patients (57.6%) were subsequently hospitalized (1.3% of all admissions): 48.0% of the admissions were admitted to a general medical ward, 29.3% to an observation ward, 13.3% to a cardiology section, 1.6% to a neurology section and 7.8% to other clinical sections (neurosurgery, general surgery). The mean duration of in-hospital stay was 6.9 (5.8 days; range 1-40 days). During the hospitalization period, 93.1% of patients underwent an ECG, 51.0% an EEG, 44.3% a CT scan of the central nervous system, 40.2% an echocardiogram and 19.5% a tilt-test. The syncope spell was considered to have a cardiovascular origin in 33.8% of the cases and a non-cardiovascular in 11.6% of the cases, while the origin was unknown in 54.4% of the cases. CONCLUSIONS: Collected data support the idea that syncope represents a frequent event in the general population and is responsible for a significant percentage of emergency-room visits and hospital admissions. However, the performance of conventional diagnostic work-ups is far from being satisfactory.

Spatial extension of local pacing capture in the lateral free wall of the right atrium during clinical chronic atrial fibrillation.

OBJECTIVES: The aims of our study were to define the spatial extension of local atrial pacing capture (LAPC) in the right lateral atrial wall and to verify the effects of antiarrhythmic drugs on capture extension. BACKGROUND: Recently, LAPC during spontaneous chronic atrial fibrillation (AF) has been demonstrated directly in humans, but no systematic attempt has been made to evaluate its spatial extension. METHODS: The study was conducted in 14 consecutive patients with chronic AF, nine of whom were taking antiarrhythmic drugs. A Franz catheter for pacing and monophasic action potential recording was positioned in the lateral right atrial wall. An octopolar recording lead was positioned about 10 mm apart. The presence of atrial capture and its extension (number of captured bipolar pairs) were evaluated during decremental pacing. RESULTS: Forty-eight atrial capture attempts were made. LAPC was achieved in all the performed attempts. The AF types immediately before capture were type 1 in 35 (73%) and type 2 in 13 (27%) episodes. In 32 episodes, the capture was lost within 15 seconds and in the remaining 16 pacing was stopped after 15 seconds of stable capture. In 26 episodes, capture extended radially up to 4 cm from the pacing site, in 18 up to 3 cm, in 3 up 1 cm and in 1 up 1 cm. The mean extension in patients being treated with antiarrhythmic drugs was significantly greater than what was seen in untreated patients (3.8 +/- 0.4 vs 2.9 +/- 0.7 cm, p < 0.00001). Capture loss was less frequently observed when all four of the bipolar recording sites had been captured (13/25, 52% vs 19/23, 82%, respectively, p = 0.05). CONCLUSIONS: LAPC in the lateral right atrial wall extends over a radius of 30-40 mm in the majority of capture episodes and is greater in patients treated with antiarrhythmic drugs. Our results suggest that, at least theoretically, simultaneous multisite pacing could be used to terminate AF. Moreover, a reduction in the atrial defibrillation threshold could be expected performing low-energy internal cardioversion during LPC.

Electrophysiological characteristics of the human atria after cardioversion of persistent atrial fibrillation.

BACKGROUND: In animal models, induced atrial fibrillation shortens the atrial effective refractory period (ERP) and reverses its physiological adaptation to rate. It is not clear whether this process, known as "electrical remodeling," occurs in humans. METHODS AND RESULTS: We determined the ERPs, at 5 pacing cycle lengths (300 to 700 ms) and in 5 right atrial sites, after internal cardioversion of chronic atrial fibrillation in 25 patients (14 in pharmacological washout and 11 on amiodarone). The ERPs were 195.5+/-18.8 ms in the washout and 206.3+/-17.9 ms in the amiodarone patients (P<0.0001). ERPs were closely correlated with the stimulation rates (r=0.95 in the washout and r=0.94 in the amiodarone group), and slope values indicating a normal (>/=0.07) or nearly normal (0.05 to 0.06) adaptation of ERP to rate were found in 77% of the 84 paced sites. The mean ERP was shorter in the lateral wall (198.1+/-17.9 ms) than in the atrial roof (203.3+/-21.5 ms) and in the septum (210.5+/-20.0 ms) (P<0.03). After 4 weeks of sinus rhythm, the mean ERP, determined again in 8 patients (4 in wash-out and 4 on amiodarone), was significantly increased compared with the basal study (221. 4+/-21.4 versus 197.8+/-18.3 ms, P<0.0001). CONCLUSIONS: After cardioversion of chronic atrial fibrillation, (1) atrial ERP adaptation to rate was normal or nearly normal in the majority of the cases, (2) a significant dispersion of refractoriness between different right atrial sites was present, and (3) ERPs were significantly increased after 4 weeks of sinus rhythm in both washout and amiodarone patients.

DDD pacing with rate drop response function versus DDI with rate hysteresis pacing for cardioinhibitory vasovagal syncope.

BACKGROUND: The effectiveness of cardiac pacing in preventing vasovagal syncope remains controversial. However, DDI pacing with rate hysteresis has been reported to prevent the recurrence of cardioinhibitory vasovagal syncope in up to 35% of affected subjects and to reduce the overall incidence of syncopal episodes in the others. Recently, DDD pacing with a new promising rate drop response function (Medtronic Thera-I model 7960) has become available in clinical practice. AIM OF THE STUDY: The aim of the present open trial was to test the effectiveness of this new pacing modality in patients with cardioinhibitory vasovagal syncope. STUDY POPULATION AND METHODS: The study population included 20 patients (12 males and 8 females; mean age 61.1 +/- 14 yrs) with recurrent syncope (mean number of prior episode = 6.8, range 5-11) and cardioinhibitory responses during two head-up tilt tests: the first diagnostic and the second during drug therapy with either beta-blockade or etilephrine. The study patients were randomized to receive either DDI pacing with rate hysteresis (8 patients) or DDD pacing with rate drop response function (11 patients). The head-up tilt test performed 1 month after pacemaker implantation was positive in 3 of 12 patients (25%) with DDD pacing with rate drop response function and in 5 of 8 patients (62.5%) with DDI pacing with rate hysteresis. The mean duration of follow-up was 17.7 +/- 7.4 months. During follow-up no patients with a DDD pacemaker with rate drop response function had syncope, while 3 of 8 patients with a DDI pacemaker with rate hysteresis had recurrence of syncope (P < 0.05). CONCLUSIONS: These data suggest that DDD pacing with rate drop response function is effective in cardioinhibitory vasovagal syncope and may be preferable to DDI pacing with rate hysteresis.

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.