Research in Review

Am J Cardiol. 2004 Dec 15;94(12):1491-5.

Frequency of arrhythmic events during head-up tilt testing in patients with suspected neurocardiogenic syncope or presyncope.

Kim PH, Ahn SJ, Kim JS.

Division of Cardiology, Cardiac and Vascular Center, Samsung Medical Center, Department of Internal Medicine, Sungkyunkwan University School of Medicine, Seoul, Korea.

Head-up tilt testing (HUT) is a useful diagnostic tool for evaluating suspected neurocardiogenic syncope. Although arrhythmic events during HUT have been occasionally reported, their incidence in a large number of patients is unknown. We aimed to assess the incidence and clinical significance of arrhythmic events in patients with suspected neurocardiogenic syncope who underwent HUT with isoproterenol provocation.

For 2,242 patients who underwent HUT, the incidence of total arrhythmic events was 31%: bradyarrhythmias 24%, premature beats 4%, and tachyarrhythmias 3%. For 547 patients who developed bradyarrhythmias during HUT, the incidence of junctional arrhythmias was 92%. For 702 arrhythmic events, the incidence of arrhythmic events during the first phase of HUT was significantly lower than the second phase (p <0.001). The incidence of arrhythmic events in patients with positive HUT responses was significantly higher than in those with negative responses (p <0.001).

In patients with positive responses, bradyarrhythmias were noted in 85%, and junctional arrhythmia was the most common arrhythmic event. Of the positive responses, 353 patients (61%) had the vasodepressive type, 181 (32%) patients the mixed type, and the remaining 39 (7%) the cardioinhibitory type. Of 2,242 patients, ventricular fibrillation occurred in 1 patient (0.04%). Thus, bradyarrhythmias were the most common arrhythmic events during HUT with isoproterenol provocation. Serious ventricular tachyarrhythmia rarely occurred.

PMID: 15589002

Circulation. 2005 Feb 7

Neurocirculatory Abnormalities in Chronic Orthostatic Intolerance.

Goldstein DS, Eldadah B, Holmes C, Pechnik S, Moak J, Sharabi Y.

Clinical Neurocardiology Section, NINDS, National Institutes of Health, Bethesda, Md.

BACKGROUND: Chronic orthostatic intolerance (COI) occurs in postural tachycardia syndrome (POTS) and in some individuals with repeated neurocardiogenic syncope/presyncope (NCS), without POTS. This study addressed whether patients with COI and POTS or NCS have neurocirculatory abnormalities during supine rest.

METHODS AND RESULTS: Adult patients referred for COI who had POTS (n=90, mean+/-SEM age 40+/-1 years, 86% women) or NCS (n=36, 41+/-2 years old, 78% women) underwent measurements of plasma levels of catecholamines and forearm hemodynamics. Comparison data were obtained from 32 age- and gender-matched normal volunteers (39+/-2 years old, 81% women). The POTS group had a relatively fast mean heart rate (79+/-2 bpm) during supine rest compared with the NCS group (69+/-1.6 bpm, P=0.03) and normal volunteers (66+/-3 bpm, P=0.0004). The POTS group also had higher mean arterial norepinephrine (1.61+/-0.11 nmol/L, n=37) and epinephrine (0.39+/-0.03 nmol/L, n=37) concentrations than the NCS group (1.03+/-0.12 nmol/L, n=20, P=0.0012; 0.21+/-0.03 nmol/L, n=20, P=0.0005) and normal volunteers (1.13+/-0.11 nmol/L, n=20, P=0.006; 0.17+/-0.03 nmol/L, n=15, P=0.0001). The NCS group had higher mean forearm vascular resistance (52+/-6 U) than the POTS group (36+/-2 U, P=0.003).

CONCLUSIONS: Overall, POTS features increased heart rate and sympathetic nervous and adrenomedullary hormonal system outflows during supine rest. Increased sympathetic outflow may contribute to the relative tachycardia in POTS. NCS features forearm vasoconstriction during supine rest but not sympathoneural or adrenomedullary activation.

PMID: 15699262

Curr Hypertens Rep. 2005 Feb;7(1):17-20.

Effect of water drinking on sympathetic nervous activity and blood pressure.

Jordan J.

Clinical Research Center, Haus 129, Wiltbergstrasse 50, D-13125 Berlin, Germany. jordan@fvk-berlin.de.

Recent studies suggest that water drinking elicits acute changes in human physiology. Water drinking profoundly increases blood pressure in patients with autonomic failure. Water drinking also increases blood pressure in quadriplegic patients, cardiac transplant recipients, and older healthy subjects, but to a lesser extent. Blood pressure does not change in healthy young subjects. More recently, water drinking was shown to increase energy expenditure. The acute changes in cardiovascular regulation and in energy expenditure with water drinking appear to be mediated through activation of the sympathetic nervous system. The sympathetic activation may involve a spinal reflex-like mechanism. The stimulus that causes the sympathetic activation is not known. The acute water pressor response can be exploited in the treatment of patients with impaired orthostatic tolerance caused by autonomic failure, postural tachycardia syndrome, or, perhaps, neurocardiogenic (vasovagal) syncope. The increase in energy expenditure with water drinking should be recognized as an important confounding variable in metabolic studies and may hold some promise as an adjunctive measure in the prevention or treatment of obesity.

PMID: 15683582

Europace. 2005 Jan;7(1):1-13.

"Cardioneuroablation" - new treatment for neurocardiogenic syncope, functional AV block and sinus dysfunction using catheter RF-ablation.

Pachon M JC, Pachon M EI, Pachon M JC, Lobo TJ, Pachon MZ, Vargas RN, Jatene AD.

Sao Paulo Heart Hospital and Dante Pazzanese Cardiology Institute, Pacemaker and Arrhythmias, Acoce, 515/31 Indianopolis, 04075023 Sao Paulo, SP, Brazil.

Cardiac neuroablation is a new technique for management of patients with dominantly adverse parasympathetic autonomic influence. The technique is based on radiofrequency (RF) ablation of autonomic connections in the three main ganglia around the heart. Their connections are identified by Fast-Fourier Transforms (FFTs) of endocardial signals: sites of autonomic nervous connections show fractionated signals with FFTs shifted to the right. In contrast, normal myocardium without these connections does not show these features. RF-ablation is thought to inflict permanent damage on the parasympathetic autonomic influence because its cells are adjacent to the heart whereas sympathetic cells are remote. Twenty-one patients with a mean age of 48 years, neurally mediated reflex syncope in six, functional high grade atrioventricular block in seven and sinus node dysfunction in 13 (there is overlap between the second and third groups) were treated. Follow-up for a mean of 9.2 months demonstrated success in all cases with relief of symptoms. No complications occurred.

PMID: 15670960

Wien Klin Wochenschr. 2004;116 Suppl 1:40-6.

[Orthostatic intolerance--prevalence, diagnostic management and its significance for occupational medicine]

[Article in German]

Winker R.

Klinische Abteilung fur Arbeitsmedizin der Universitat Wien, Wien, Osterreich. robert.winker@akh-wien.ac.at

OBJECTIVE: Orthostatic intolerance (OI) is a syndrome which is characterised by headache, concentration difficulties, palpitation of the heart, dizziness associated with postural tachycardia and plasma norepinephrine concentrations that are disportionately high in upright posture. OI hitherto can only be diagnosed by a tilt table examination with high expenditure. In this paper we examine the reliability and validity of a questionnaire as a screening instrument for OI.

METHODS: We studied 138 young males (mean age 21.6 years) from the military service. After a medical check and filling in the questionnaire, the participants underwent a tilt table test. The questionnaire consisted of 10 items registering presence and frequency of typical OI-symptoms.

RESULTS: 104 probands showed a normal tilt table test. OI was diagnosed in 14 probands, orthostatic hypotension (OH) in 6 and postural orthostatic tachycardia syndrome (POTS) in 14. The participants with OI scored significantly higher in the questionnaire than the normal subjects: The mean score of the OI group was 22.6, the normal participants had a mean score of 3.9. Participants with POTS had a mean score of 13.5 and subjects with OH had a mean score of 17.0.

CONCLUSIONS: We were able to establish a short questionnaire as a reliable and valid screening instrument for OI. Usage of this questionnaire can simplify enormously the diagnostic management of patients with suspected OI.

PMID: 15518091 [PubMed - in process]

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