A few abstracts (technical) re ANS and AF for anyone interested..........

: J Cardiovasc Electrophysiol. 2001 May;12(5):592-9. Related Articles, Links

Comment in:
· J Cardiovasc Electrophysiol. 2001 May;12(5):600-1.

Focal atrial fibrillation: experimental evidence for a pathophysiologic role of the autonomic nervous system.

Schauerte P, Scherlag BJ, Patterson E, Scherlag MA, Matsudaria K, Nakagawa H, Lazzara R, Jackman WM.

Department of Internal Medicine, University of Oklahoma Health Sciences Center, Oklahoma City, USA. psch@pcserver.mk1.rwth-aachen.de

INTRODUCTION: Focal paroxysmal atrial fibrillation (AF) was shown recently to originate in the pulmonary veins (PVs) and superior vena cava (SVC). In the present study, we describe an animal model in which local high-frequency electrical stimulation produces focal atrial activation and AF/AT (atrial tachycardia) with electrogram characteristics consistent with clinical reports. METHODS AND RESULTS: In 21 mongrel dogs, local high-frequency electrical stimulation was performed by delivering trains of electrical stimuli (200 Hz, impulse duration 0.1 msec) to the PVs/SVC during atrial refractoriness. Atrial premature depolarizations (APDs), AT, and AF occurred with increasing high-frequency electrical stimulation voltage. APD/AT/AF originated adjacent to the site of high-frequency electrical stimulation and were inducible in 12 of 12 dogs in the SVC and in 8 of 9 dogs in the left superior PV (left inferior PV: 7/8, right superior PV: 6/8; right inferior PV: 4/8). In the PVs, APDs occurred at 13+/-8 V and AT/AF at 15+/-9 V (P < 0.01; n = 25). In the SVC, APDs were elicited at 19+/-6 V and AT/AF at 26+/-6 V (P < 0.01; n = 12). High-frequency electrical stimulation led to local refractory period shortening in the PVs. The response to high-frequency electrical stimulation was blunted or prevented after beta-receptor blockade and abolished by atropine. In vitro, high-frequency electrical stimulation induced a heterogeneous response, with shortening of the action potential in some cells (from 89+/-35 msec to 60+/-22 msec; P < 0.001; n = 7) but lengthening of the action potential and development of early afterdepolar-izations that triggered APD/AT in other cells. Action potential shortening was abolished by atropine. CONCLUSION: High-frequency electrical stimulation evokes rapid ectopic beats from the PV/SVC, which show variable degrees of conduction block to the atria and induce AF, resembling findings in patients with focal idiopathic paroxysmal AF. The occurrence of the arrhythmia in this animal model was likely due to alterations in local autonomic tone by high-frequency electrical stimulation. Further research is needed to prove absolutely that the observed effects of high-frequency electrical stimulation were caused by autonomic nerve stimulation.

Ter Arkh. 2001;73(9):55-61. Related Articles, Links

[Psychoautonomic correlations in patients with paroxysmal atrial fibrillation]

[Article in Russian]

Nedostup AV, Solov'eva AD, San'kova TA.

AIM: To study psychovegetative correlations in patients with paroxysmal atrial fibrillation (PAF). MATERIAL AND METHODS: The trial included 50 patients with non-rheumatic PAF and 20 healthy subjects. Clinical cardiological and cliniconeurological examinations, assessment of autonomic nervous system, emotional sphere, sleep disorders were performed. RESULTS: The diagnosis of marked psychovegetative syndrome was made in all PAF patients. It manifested stronger in older women, young men, survivors of myocardial infarction or acute disorders of cerebral circulation, in frequent paroxysms of cardiac fibrillation, its long-term history, in night PAF attacks, in sleep apnea. CONCLUSION: The policy of antiarrhythmic antirecurrence therapy should consider modalities correcting psychovegetative disorders.

J Cardiovasc Electrophysiol. 2001 Mar;12(3):285-91. Related Articles, Links

Comment in:
· J Cardiovasc Electrophysiol. 2001 Mar;12(3):292-3.

Fluctuation in autonomic tone is a major determinant of sustained atrial arrhythmias in patients with focal ectopy originating from the pulmonary veins.

Zimmermann M, Kalusche D.

Cardiology Department, Hopital de La tour, Meyrin, Switzerland. zimmermann.family@bluewin.ch

INTRODUCTION: This study was designed to analyze dynamic changes in autonomic tone preceding the onset of sustained atrial arrhythmias in patients with focal atrial fibrillation (AF) to determine why patients with frequent discharge from the arrhythmogenic foci develop sustained AF. METHODS AND RESULTS: Holter tapes from 13 patients (10 men and 3 women; mean age 53 +/- 5 years) with paroxysmal "lone" AF (mean 18 +/- 13 episodes per week) and a proven focal origin (pulmonary veins in all cases) were analyzed. A total of 38 episodes of sustained (>30 min) were recorded and submitted to frequency-domain heart rate variability analysis. Six periods were studied using repeated measures analysis of variance: the 24-hour period, the hour preceding AF, and the 20 minutes before AF divided into four 5-minute periods. A significant increase in high-frequency (HF, HF-NU) components was observed during the 20 minutes preceding AF (P = 0.003 and 0.002, respectively), together with a progressive decrease in normalized low-frequency (LF-NU) components (P = 0.035). An increase in LF/HF ratio followed by a linear decrease starting 15 minutes before sustained AF also was observed, indicating fluctuations in autonomic tone, with a primary increase in adrenergic drive followed by a marked modulation toward vagal predominance immediately before AF onset. CONCLUSION: In patients with focal ectopy originating from the pulmonary veins, sustained episodes of atrial arrhythmias are mainly dependent on variations of autonomic tone, with a significant shift toward vagal predominance before AF onset.

J Investig Med. 1999 Jul;47(6):293-303. Related Articles, Links

Verapamil prolongs atrial fibrillation by evoking an intense sympathetic neurohumoral effect.

[www.ncbi.nlm.nih.gov]

Eur J Pharmacol. 1998 Aug 28;356(1):31-40. Related Articles, Links

Effects of pilsicainide and propafenone on vagally induced atrial fibrillation: role of suppressant effect in conductivity.

Iwasa A, Okumura K, Tabuchi T, Tsuchiya T, Tsunoda R, Matsunaga T, Tayama S, Yasue H.

Division of Cardiology, Kumamoto University School of Medicine, Japan.

The effects of pilsicainide on vagally induced atrial fibrillation and on electrophysiological parameters were compared with those of propafenone in alpha-chloralose-anesthetized dogs. Conduction velocity, effective refractory period, wavelength, averaged atrial fibrillation cycle length and activation sequence in the right atrial free wall were determined before and after drug administration. Pilsicainide (2 mg/kg/5 min and 3 mg/kg/h)(n=10) or propafenone (2 mg/kg/15 min and 4 mg/kg/h)(n=10) was intravenously infused during stable atrial fibrillation sustaining > 30 min. Pilsicainide terminated atrial fibrillation in nine dogs, while propafenone did so in three (p < 0.01). After the drug, conduction velocity was suppressed more in the pilsicainide than in the propafenone group(p < 0.01). There was no difference in effective refractory period after drug between the two groups. Mean wavelength was prolonged from 46.0 to 70.4 mm in the pilsicainide group and from 45.0 to 110.8 mm in the propafenone (p < 0.01 vs. pilsicainide). Activation mapping during atrial fibrillation showed Type II or III atrial fibrillation as previously defined [Konings, K.T.S., Kirchhof, C.J.H.J., Smeets, J.R.L.M., Wellens, H.J.J., Penn, O.C., Allessie, M.A., 1994. High-density mapping of electrically induced atrial fibrillation in humans. Circulation. Vol. 89, pp. 511-521.] before the drug, and changed to Type I before atrial fibrillation termination. Thus, pilsicainide was more effective to terminate vagally induced atrial fibrillation than was propafenone despite a greater effect of propafenone than of pilsicainide on wavelength. In this canine atrial fibrillation model, the suppression of conduction velocity may play an important role in changing the activation pattern of atrial fibrillation and thus, terminating atrial fibrillation.
[www.ncbi.nlm.nih.gov]

Pacing Clin Electrophysiol. 1998 Feb;21(2):386-95. Related Articles, Links

Abnormal vasovagal reaction, autonomic function, and heart rate variability in patients with paroxysmal atrial fibrillation.

Lok NS, Lau CP.

Department of Medicine, Queen Mary Hospital, Hong Kong.

The aim of this study was to evaluate the cardiovascular autonomic function and vasovagal reaction in patients with paroxysmal atrial fibrillation without significant structural heart disease. Twenty-eight patients with paroxysmal atrial fibrillation (9 patients were categorized to have autonomic-mediated atrial fibrillation while atrial fibrillation in other patients was nonautonomic mediated) and 19 normal control subjects were recruited. Cardiovascular autonomic function tests included measuring heart rate response to standing, deep breathing, Valsalva maneuver, baroreflex sensitivity, 24-hour heart rate variability, and also head-up tilt test. Compared with normal subjects, no significant autonomic dysfunction was found in patients with autonomic-mediated and nonautonomic-mediated atrial fibrillation. All subjects had negative baseline tilt test. With isoproterenol provocation, six patients developed atrial fibrillation. Four of 9 patients and 3 of 19 patients with autonomic mediated and nonautonomic mediated atrial fibrillation had a positive tilt test respectively, while none occurred in the controls. A significant percentage (32%) of patients with paroxysmal atrial fibrillation had episodes of atrial fibrillation provoked by changes in autonomic tone, although there was no underlying abnormal cardiac autonomic function nor sympathetic-parasympathetic imbalance. A heightened susceptibility to vasovagal cardiovascular response may have important implications on the occurrence and symptomatology of patients with paroxysmal atrial fibrillation.
[www.ncbi.nlm.nih.gov]

Mike,

Love that word "psychovegetative".

Does that describe someone who spends too much time on a computer?

Dean

Would somebody like to translate that term for me? I am assuming the author did not mean to refer to aberrant plant life, but then what do i know?
Peggy

"Love that word "psychovegetative"."
LOL
Me too. I'd like to think it means a tv addict.

William

Dean,

Quite possibly! I found these articles in my computer briefcase put there from a recent phase of excessive obsessing about my AF at the computer. Thought I'd post 'em before binning 'em.

Mike F.

Mike, i hate to press you about this, but are you sauing that you don't know what ti means either?
Peggy

Mike,

I found your studies quite interesting, and want to thank you for sharing. You know, I miss your presence and postings here.

The psychovegetative state, is I believe, to mean a depression of the central nervous system. I did a quick search and found the following, not necessarily to completed apply, but to indicate a usefulness in upping the dopaminergic response. That follows the path of what I discussed on my post about my sympathetic system being suppressed. Here's some excerpts on persistent vegetative state:

One group of agents which have been studied are dopaminergic agents which act as catecholaminergic agonists (activators), and have been shown to have positive effects on patients with other disorders including akinetic mutism, hepatic coma, and brain damage with avolitional states. Because of this, there have been studies on the effect of levodopa (L-dopa) and combined carbidopa/levodopa therapies. These therapies do seem to have positive effects, and individuals treated with this drug therapy have shown significant recovery. For example one 51-year-old man who was diagnosed with PVS several months following an automobile accident was administered L-dopa. Remarkable neurological recovery occurred though this treatment which helps in repairing damaged dopaminergic systems (Matsuda, et.al.). However, these tests have not been performed in a large enough scale to provide definitive information. There has been a lack of controlled trials in determining the effectiveness of these drugs. Along with this there is the previously mentioned fact that there are different levels of spontaneous recovery for patients that are diagnosed as being in PVS.

There is also much thought that certain drugs can have negative effects on the recovery of patients in PVS. Drug categories such as catecholaminergic antagonists, anticholinergics, GABA agonists and serotonergic agonists are thought to inhibit recovery for patients in PVS. These drugs are thought to have negative effects because they work against the stimulation of neurons in the CNS, and it is the stimulation of the CNS that is thought to be beneficial to the recovery of persons in PVS. Because of the adverse affects of some drugs, there is caution in using them for the treatment of clinical conditions for patients in PVS. For example, drugs that are used in the treatment of epilepsy and spasticity fall into the category of drugs that are considered to be detrimental to the recovery of patients in PVS.

[www.cwu.edu]

Have a wonderful holiday, Mike, and hope to see more postings from you.

Richard

Thanks for the info, Mike. Please keep 'em coming.

LarryG
V / 55