Heart Vessels. 1998;13(3):122-31.      Related Articles, Links

 

Magnesium deficiency in adult rats promotes the induction of ventricular tachycardia by the administration of epinephrine.

Tomiyasu T, Chishaki A, Nakamura M.

The Graduate School of Health and Nutrition Sciences, Nakamura-Gakuen University, Fukuoka, Japan.

The effects of magnesium deficiency on epinephrine-induced ventricular tachyarrhythmia were investigated in adult rats. Forty-two adult Wistar rats were fed a magnesium-deficient diet while 30 rats were fed a standard diet for 20 days. The plasma magnesium concentration was lower in the magnesium-deficient rats (0.22+/-0.01 mmol/l) than in the control rats (0.76+/-0.03 mmol/l, P < 0.001). Using a telemetry system, electrocardiograms and arterial blood pressure were recorded on a polygraph in an unrestrained condition. Epinephrine was infused intravenously starting at 5 microg/kg per minute. The QT interval was prolonged to 50+/-1 ms in the magnesium-deficient rats compared with 44+/-1 ms in the control rats (P < 0.001). Before the administration of epinephrine, no ventricular tachyarrhythmias or seizures were found in either the control or the magnesium-deficient rats. The incidence of epinephrine-induced sustained ventricular tachycardia (VT) was higher in the magnesium-deficient rats (86%) than in the control rats (43%, P < 0.01). However, this VT did not result in sudden death. Seizures always preceded death in both the magnesium-deficient and control rats while the arrhythmias observed immediately before death were mainly bradyarrhythmias. The present study in an adult rat magnesium-deficient model revealed that magnesium deficiency enhances the susceptibility to epinephrine-induced ventricular tachyarrhythmias.

PMID: 10328182 [PubMed - indexed for MEDLINE]

 

Am J Clin Nutr. 2002 Mar;75(3):550-4.              Related Articles, Links

 

Low dietary magnesium increases supraventricular ectopy.

Klevay LM, Milne DB.

US Department of Agriculture, Agricultural Research Service, Grand Forks Human Nutrition Research Center, ND 58202-9034, USA. lklevay@gfhnrc.ars.usda.gov

BACKGROUND: Magnesium has been suggested to be beneficial in counteracting all phases of the processes that lead to ischemic heart disease, including terminal events such as arrhythmia and sudden death. OBJECTIVE: We tested the hypothesis that an intake of magnesium considerably below the recommended dietary allowance can produce chemical and physiologic evidence of depletion. DESIGN: Twenty-two postmenopausal women were maintained in a metabolic unit and ate a diet of conventional foods containing less than one-half of or more than the recommended dietary allowance for magnesium (320 mg/d). Dietary assignments were random and double blind in a crossover design. Magnesium concentrations were measured by spectroscopy and ion-specific electrolyte analysis, and Holter electrocardiograms lasting approximate 21 h were recorded. RESULTS: Magnesium concentrations in erythrocytes, serum (total and ultrafilterable), and urine were significantly lower when dietary magnesium was lower. Holter monitors showed a significant increase in both supraventricular and supraventricular plus ventricular beats when the dietary magnesium concentration was low. Hypomagnesemia, hypocalcemia, and hypokalemia were not found. CONCLUSIONS: The magnesium requirement was defined with the use of biochemical and electrophysiologic criteria. The recommended dietary allowance of 320 mg/d seems correct; 130 mg is too little. Persons who live in soft water areas, who use diuretics, or who are predisposed to magnesium loss or ectopic beats may require more dietary magnesium than would others.

Publication Types:

Clinical Trial

Randomized Controlled Trial

PMID: 11864862 [PubMed - indexed for MEDLINE]

J Trace Elem Med Biol. 1998 Mar;12(1):28-38.

 

Trace elements and cardioprotection: increasing endogenous glutathione peroxidase activity by oral selenium supplementation in rats limits reperfusion-induced arrhythmias.

Tanguy S, Boucher F, Besse S, Ducros V, Favier A, de Leiris J.

Physiopathologie Cellulaire Cardiaque, CNRS ESA 5077, Universite J. Fourier, Grenoble, France.

Oxyradicals have been implicated as a possible cause of reperfusion-arrhythmias (RA). However, the use of diverse exogenous oxyradical scavengers designed to reduce RA has given contradictory results. The aim of the present study was to determine whether enhancing the activity of the main endogenous enzyme involved in peroxide elimination in cardiac cells, namely glutathione peroxidase, may limit RA in isolated heart preparations by increasing their antioxidant status. For this purpose, a group of 15 male Wistar rats received a selenium enriched diet for ten weeks (1.5 mg Se/kg diet). Control animals (n = 15) received a standard diet containing 0.05 mg Se/kg diet. The incidence of early ventricular arrhythmias was investigated during the reperfusion period following 10 min regional ischemia induced ex-vivo by left coronary artery ligation. Our results show that selenium-supplementation significantly increased the global selenium status of the animals. In the isolated heart preparations, the selenium supplementation induced a significant reduction of the severity of RA as assessed by the arrhythmia score and the limitation of the incidence of both ventricular tachycardia (control: 91% vs selenium: 36%, p < 0.05) and irreversible ventricular fibrillation (control: 45% vs selenium: 0%, p < 0.05). These effects were associated with a significant increase in cardiac mitochondrial and cytosolic glutathione peroxidase activities in both the left and the right ventricles. These results illustrate the potential protective effect of selenium against ischemia-reperfusion injury and suggest that peroxides might play a key role in the genesis of some aspects of the reperfusion syndrome.

PMID: 9638610 [PubMed - indexed for MEDLINE]

 

Arch Mal Coeur Vaiss. 2003 Sep;96 Spec No 6:7-12.

 

[Heart and nutrition: which fatty acids for which cardiac function?]

[Article in French]

Grynberg A.

INRA UR 1154, faculte de pharmacie, universite Paris-Sud, 5, rue Jean-Baptiste Clement, 92296 Chatenay-Malabry. grynberg@jouy.inra.fr

Cardiovascular risk factors are often related to diet and the dietary fatty acids play a leading role quantitatively and qualitatively. In addition to the demonstration of the beneficial properties of n-3 PUFA on the development of atherosclerosis, there is a growing body of experimental evidence on the implication of n-3 PUFA in the regulation of cardiac function because of cardiac enrichment with n-3 PUFA to the detriment of arachidonic acid. The antiarrhythmic effect of these PUFA has been demonstrated in several animal species, the positive results of the GISSI-prevenzione study being partially associated with this property. This effect is related to the presence of DHA in cardiac phospholipids but the molecular mechanism is poorly understood. Moreover, the presence of DHA in the membranes decreases the production of cAMP induced by a b-adrenergic stimulation. This characteristic related to the interaction between the protein receptor complex and its environment provokes effects similar to those of a betablocker specifically due to the presence of DHA and not to the decrease in arachidonic acid. Finally, n-3 PUFA induce a reduction of cardiac b-oxidation and oxygen consumption in the animal. This effect, mild under physiological conditions, manifests itself during post-ischaemic reperfusions as an improvement of metabolic recovery and ventricular function. In conclusion, the relationship between the heart and fatty acids will change because of the increasing incidence of cardiac failure associated with a chronic catabolic state. Daily dietary PUFA, in particular the n-3 forms, is insufficient, especially when a hypertrophic heart has to increase its membrane mass. In view of the positive effects of a high BMI on morbi-mortality of cardiac failure, nutrition and cardiology may have to reinforce their relationship in the short-term.

Publication Types:

Review

Review, Tutorial

PMID: 14655544 [PubMed - indexed for MEDLINE]

Pathophysiol Haemost Thromb. 2002 Sep-Dec;32(5-6):361-4.

 

Polyunsaturated fatty acids, thrombosis and vascular disease.

Di Minno G, Tufano A, Garofano T, Di Minno MN.

Clinica Medica, Dipartimento di Medicina Clinica e Sperimentale, Universita' degli Studi di Napoli Federico II, Italy. diminno@unina.it

In the 80's, retrospective studies showed an inverse relation between fish consumption and ischemic heart disease (IHD) mortality. In parallel, fish fats containing the polyunsaturated fatty acid (PUFA) eicosapentaenoic (EPA) were shown to impair platelet aggregation and thromboxane formation. The results of the large prospective trials, the Diet and Reinfarction Trial (DART) and the Lyon Heart Study in the secondary prevention of myocardial infarction, have further supported the interrelationships between diet and dietary prevention of IHD. In the DART Study, the cardioprotection by EPA was paralleled by an increase plasma content of EPA. In the Lyon, in addition to changes in the content of EPA, changes in other well known variables (i.e. leukocytes and vitamin E), often abnormal in subjects prone to arterial thrombosis, have been found. The GISSI Prevenzione Trial was a prospective, multicentric, open labeled trial with a factorial design, in which 11,324 recent (<3 mo) survivors of a first myocardial infarction were assigned to receive, in addition to the usual strategy, a supplementation of n-3 PUFA, vitamin E, or the combination of the two. Cardiovascular death (-30%), coronary heart disease death (-35%), total death (-20%) and sudden death (-45%) were all significantly reduced by the n-3 PUFA supplementation. The reduced tendency to sudden death of survivors of myocardial infarction on treatment with n-3 PUFA are in keeping with a series of scanty but reliable clinical data as well as of experimental studies. However, we believe that large-scale prospective multicentric randomized trials aimed at preventing sudden death in high-risk patients as well as at testing the effects of n-3 PUFA in patients with intracoronary devices and sustained ventricular arrhythmias, are a major direction to be followed to better understand the n-3 PUFA and sudden death issue.

Publication Types:

Review

Review Literature

PMID: 13679677 [PubMed - indexed for MEDLINE]

 

Clin Exp Pharmacol Physiol. 2003 Jul;30(7):446-51.

 

Insulin resistance modifies plasma fatty acid distribution and decreases cardiac tolerance to in vivo ischaemia/reperfusion in rats.

Morel S, Berthonneche C, Tanguy S, Toufektsian MC, Foulon T, de Lorgeril M, de Leiris J, Boucher F.

Laboratoire Stress Cardiovasculaires et Pathologies Associees, Universite Joseph Fourier and Departement de Biologie Integree du CHU, Grenoble, France.

1. The early stage of insulin resistance, also termed the 'prediabetic state', is characterized by the development of hyperinsulinaemia, which maintains normoglycaemia under fasting conditions. The metabolic disorders induced in myocardial cells during this stage of the disease may constitute a basis for an alteration of the tolerance of the heart to ischaemia and reperfusion. 2. To test this hypothesis, male Wistar rats were fed a 66% fructose diet for 4 weeks, inducing a prediabetic state. Rats were then subjected to in vivo left coronary artery ligation followed by reperfusion. Blood samples were collected for plasma lipid profile determination. 3. The prediabetic state significantly increased the severity of ischaemia-induced arrhythmias (arrhythmia score 1.4 +/- 0.2 vs 2.0 +/- 0.0 in control and fructose-fed rats, respectively; P < 0.05) and the size of infarction (infarct size 41.2 +/- 3.0 vs 56.0 +/- 2.0% in control and fructose-fed rats, respectively; P < 0.01). This alteration of the tolerance to in vivo ischaemia/reperfusion may be the consequence of an increase in mono-unsaturated fatty acids and a decrease in omega3 polyunsaturated fatty acids in fructose-fed-rats. 4. In conclusion, because it is known that the prediabetic state increases the incidence of cardiovascular diseases by promoting coronaropathy, our study suggests that this metabolic disorder may also affect the prognosis of heart disease by decreasing the tolerance of cardiomyocytes to ischaemic insults.

PMID: 12823257 [PubMed - in process]

Circulation. 2002 Jun 4;105(22):2611-8.

 

Celiac disease associated with autoimmune myocarditis.

Frustaci A, Cuoco L, Chimenti C, Pieroni M, Fioravanti G, Gentiloni N, Maseri A, Gasbarrini G.

Department of Cardiology, Catholic University, Rome, Italy. biocard@rm.unicatt.it

BACKGROUND: Both celiac disease (CD) and myocarditis can be associated with systemic autoimmune disorders; however, the coexistence of the 2 entities has never been investigated, although its identification may have a clinical impact. METHODS AND RESULTS: We screened the serum of 187 consecutive patients with myocarditis (118 males and 69 females, mean age 41.7+/-14.3 years) for the presence of cardiac autoantibodies, anti-tissue transglutaminase (IgA-tTG), and anti-endomysial antibodies (AEAs). IgA-tTG-positive and AEA-positive patients underwent duodenal endoscopy and biopsy and HLA analysis. Thirteen of the 187 patients were positive for IgA-tTG, and 9 (4.4%) of them were positive for AEA. These 9 patients had iron-deficient anemia and exhibited duodenal endoscopic and histological evidence of CD. CD was observed in 1 (0.3%) of 306 normal controls (P<0.003). In CD patients, myocarditis was associated with heart failure in 5 patients and with ventricular arrhythmias (Lown class III-IVa) in 4 patients. From histological examination, a lymphocytic infiltrate was determined to be present in 8 patients, and giant cell myocarditis was found in 1 patient; circulating cardiac autoantibodies were positive and myocardial viral genomes were negative in all patients. HLA of the patients with CD and myocarditis was DQ2-DR3 in 8 patients and DQ2-DR5(11)/DR7 in 1 patient. The 5 patients with myocarditis and heart failure received immunosuppression and a gluten-free diet, which elicited recovery of cardiac volumes and function. The 4 patients with arrhythmia, after being put on a gluten-free diet alone, showed improvement in the arrhythmia (Lown class I). CONCLUSIONS: A common autoimmune process toward antigenic components of the myocardium and small bowel can be found in >4% of the patients with myocarditis. In these patients, immunosuppression and a gluten-free diet can be effective therapeutic options.

PMID: 12045166 [PubMed - indexed for MEDLINE]

 

 

 

Can J Cardiol. 2003 Jun;19(7):818-27.

 

Cardiovascular adverse effects of herbal medicines: a systematic review of the recent literature.

Ernst E.

Complementary Medicine, Peninsula Medical School, University of Exeter, Devon, United Kingdom. edzard.ernst@pms.ac.uk

Herbal medicines are popular but health care professionals often feel uncertain about their risks. This article summarizes recent evidence regarding the serious or potentially serious cardiovascular adverse effects of herbal medicines. Five electronic literature databases were searched. The evidence found was mostly anecdotal. Case reports and case series indicate that life-threatening adverse effects of herbal medicines occur. Potentially serious adverse effects are arrhythmias, arteritis, cardiac glycosides overdose, chest pain, congestive heart failure, hypertension, hypotension, myocardial infarction, over-anticoagulation, pericarditis and death. The problems relate to toxic herbal ingredients, adulteration and contamination of herbal medicinal products, and herb-drug interactions. Herbal medicines that have been implicated repeatedly include aconite, ephedra and licorice. Because of the anecdotal nature of the evidence, it is impossible to estimate the incidence of adverse effects. In conclusion, herbal medicinal products are regularly associated with serious cardiovascular adverse events but the size of this problem cannot be estimated at present. Vigilance and research seem to be the best way forward.

Publication Types:

Review

Review, Academic

Review, Multicase

PMID: 12813616 [PubMed - indexed for MEDLINE

J Anxiety Disord. 2003;17(2):197-210.

 

Embarrassment and social phobia: the role of parasympathetic activation.

Gerlach AL, Wilhelm FH, Roth WT.

Stanford University Medical School, Psych. Institute I, Westfalian Wilhelms University of Munster, Fliednerstr. 21, 48149, Munster, Germany. agerlach@uni-muenster.de

The few studies on the psychophysiology of embarrassment have suggested involvement of parasympathetic activation. However, blushing, the hallmark of embarrassment and a prominent symptom in social phobia, is more likely to be produced by cervical sympathetic outflow. Hitherto, there has been no evidence of parasympathetic innervation of the facial blood vessels. In this study, a group of social phobics and control participants watched, together with a 2-person audience, a previously made videotape of themselves singing a children's song. Self-report measures confirmed that this task induced embarrassment. While two measures of respiratory sinus arrhythmia (RSA) during the task did not indicate heightened parasympathetic tone, increased heart rate (HR) and skin conductance marked sympathetic activation. Thus, our data do not support the notion that an increase in parasympathetic activation plays a significant role in social phobia and embarrassment. Social anxiety and embarrassment both resulted in sympathetic activation.

PMID: 12614662 [PubMed - indexed for MEDLINE]

 

Forensic Sci Int. 2002 Aug 28;128(3):168-76.

 

Heart rate changes in response to mild mechanical irritation of the high cervical spinal cord region in infants.

Koch LE, Koch H, Graumann-Brunt S, Stolle D, Ramirez JM, Saternus KS.

General Practitioner, Liliencronweg 6, D-24340, Eckernforde, Germany.

Alterations in the heart rate were monitored before, during and after the application of a unilateral mechanical impulse to the high cervical spinal cord region which was administered strictly in connection with the so called manual therapy (diagnosis= KISS). The investigation is based on a survey of 695 infants between the ages of 1 and 12 months. A notable change in the heart rate was evident in 47.2% of all examined infants (n= 695). In 40.1% of these infants, the change in heart rate was characterized by heart rate decrease of 15-83% compared to control conditions. Infants in their first 3 months of life responded more often with a severe bradycardia (50-83% decrease), older infants (7-12 months) more often with a mild bradycardia (15-49.9% decrease). This comparison revealed a significantly increased occurrence of severe bradycardia in the younger age group compared to the group of children >3 months (significance 0.0017). In 12.1% (n= 84) of the infants, the bradycardia was accompanied by an apnea. We discuss the hypothesis that mechanical irritation of the high-cervical region serves as a trigger that may be involved in sudden infant death (SID).

PMID: 12175961 [PubMed - indexed for MEDLINE]

 

Can J Cardiol. 2002 Jul;18(7):763-7.

 

Differential effect of right and left carotid sinus massage: implications for sudden rate drop pacing algorithm.

Champagne J, Poirier P, O'Hara G, Gilbert M, Soucy B, Philippon F.

Electrophysiology Division, Quebec Heart Institute, Laval Hospital, Laval, Quebec.

This present report describes a patient with syncope in whom asystole was triggered by right carotid sinus massage and complete atrioventricular block with slight bradycardia by left carotid sinus massage. A dual-chamber, rate-responsive, permanent pacemaker with 'sudden rate drop' algorithm was implanted. The present report underlines the pathophysiology and the clinical utility of carotid sinus massage on both sides. Programming considerations to tailor the rate drop algorithm when two different physiological responses are triggered by carotid sinus massage are discussed. The importance of careful clinical assessment to detect all appropriate physiological responses as well as new pacing algorithms is depicted.

Publication Types:

Case Reports

PMID: 12167966 [PubMed - indexed for MEDLINE]

Pacing Clin Electrophysiol. 2001 Sep;24(9 Pt 1):1363-8.

 

Response of atrial fibrillatory activity to carotid sinus massage in patients with atrial fibrillation.

Bollmann A, Wodarz K, Esperer HD, Toepffer I, Klein HU.

Department of Cardiology, University Hospital Magdeburg, Leipziger Str. 44, 39120 Magdeburg, Germany. andreas.bollmann@medizin.uni-magdeburg.de

In some cases carotid sinus massage (CSM) may induce AF, whereas it may terminate AF in others. The purpose of this study was to investigate the influence of CSM on atrial fibrillatory frequency using spectral analysis of the surface ECG. Continuous ECG recordings were made in 19 patients (12 men, 7 women, mean age 61 +/- 11 years) with AF. Unilateral CSM was performed in the standard fashion to one randomized bifurcation of the carotid artery at a time. Ventricular rate and fibrillatory frequency were assessed in 30-second ECG segments at baseline and during CSM. The frequency content of the fibrillatory baseline was quantified using digital signal processing (filtering, subtraction of averaged QRST complexes, and Fourier transformation). CSM resulted in a relative change in fibrillatory frequency of 4.5 +/- 3.9% (range 0%-13%). In 8 (42%) patients an increase in fibrillatory frequency was found (6.4 +/- 0.5 vs 6.8 +/- 0.5 Hz, P = 0.012). In 9 (47%) patients a decrease in fibrillatory frequency occurred (6.5 +/- 0.8 vs 6.1 +/- 0.8 Hz, P = 0.008) without AF termination. The remaining two patients showed no change in fibrillatory frequency. CSM on the contralateral side after 2 minutes produced fibrillatory frequency changes in the same direction in all patients with a good reproducibility in its magnitude (r = 0.59, P = 0.05). Calcium channel blockers were more frequently used (78% vs 25%, P = 0.044) in patients with a decrease in fibrillatory frequency compared to patients with a frequency increase. There were no significant changes in ventricular rate during CSM. In conclusion, two different responses of atrial fibrillatory frequency to CSM were found. This might explain why CSM may facilitate AF induction in some cases and AF termination in others. Calcium channel blocker treatment may prevent an increase in fibrillatory frequency provoked by CSM suggesting a blunted electrical remodeling process.

PMID: 11584458 [PubMed - indexed for MEDLINE]

J Hum Ergol (Tokyo). 1998 Dec;27(1-2):30-8.

 

Influence of music on heart rate variability and comfort--a consideration through comparison of music and noise.

Umemura M, Honda K.

Department of Management Science, Science University of Tokyo, Shinjuku-ku, Tokyo, 162-8601 Japan.

By considering three kinds of music and noise, this research investigates the influence of music on the living body by comparing the difference of influence on heart rate variability and comfort when subjects listen to music and are exposed to noise. We used two pieces of classical music, rock music, and noise recorded by a tape recorder. The following conclusions were made from the findings of the research: 1) Hearing classical music results in a small variance of Mayer Wave related Sinus Arrhythmia (MWSA) component and Respiratory Sinus Arrhythmia (RSA) component compared with a body being at rest. This is because the sympathetic nerve is suppressed by the sound of classical music. With rock music and noise, however, the MWSA component increases and the RSA component decreases. 2) From a psychological evaluation, we found that classical music tends to cause comfort and rock music and noise tend to cause discomfort. 3) A correlation was found between the balance of the MWSA component and the RSA component and the psychological evaluation. As the comfort increases, the variance of MWSA decreases; as discomfort increases, the variance of MWSA increases.

Publication Types:

Clinical Trial

Controlled Clinical Trial

PMID: 11579697 [PubMed - indexed for MEDLINE]

 

Psychophysiology. 2001 May;38(3):540-7.

 

Autonomic origins of a nonsignal stimulus-elicited bradycardia and its habituation in humans.

Gianaros PJ, Quigley KS.

The Pennsylvania State University, University Park 16802, USA. pjg4@pitt.edu

The purposes of the present study were to determine the autonomic origins of a bradycardiac response to a moderate intensity nonsignal auditory stimulus and the changes in autonomic cardiac control of this response as a function of habituation. Pure tone stimuli were repeatedly presented to participants while phasic changes in heart period (HP), preejection period (PEP), and respiratory sinus arrhythmia (RSA) were observed. Tone stimuli initially elicited an increase in HP, an increase in RSA, and a decrease in PEP, suggesting a coactivation of the parasympathetic and sympathetic inputs mediating changes in the bradycardiac HP response. As expected, HP responses habituated with repeated presentations of the tones. PEP and RSA responses, however, demonstrated different habituation rates than HP. These data demonstrate that cardiodeceleratory responses to nonsignal stimuli can arise from changes in activity of both autonomic divisions and document the importance of considering the autonomic origins of habituating cardiac responses in order to fully understand the process of response habituation.

Publication Types:

Clinical Trial

PMID: 11352143 [PubMed - indexed for MEDLINE]

Arzneimittelforschung. 2001 Jan;51(1):24-8.

 

Effect of long-term application of Crataegus oxyacantha on ischemia and reperfusion induced arrhythmias in rats.

Rothfuss MA, Pascht U, Kissling G.

Physiologisches Institut II, Universitat Tubingen, Tubingen, Germany.

The effect of long-term application of Crataegus oxyacantha on ischemia and reperfusion induced arrhythmias was investigated in Wistar rats on the heart in situ and on Langendorff preparations. Seventeen rats were fed for 8 weeks with 0.5 g/kg b.w. Crataegus extract per day, standardised to 2.2% flavonoids. Twenty age-matched untreated rats served as controls. In the hearts in situ as well as in the Langendorff preparations the left anterior descending coronary artery (LAD) was ligated for 20 min and subsequently reperfused for 30 min. ECG was continuously recorded and the time spent between start of ischemia and onset of arrhythmias was measured. In addition, during ischemia and reperfusion the number of ventricular premature beats and bigemini and the duration of salvos and ventricular flutter and fibrillation were determined. The ischemic area was evaluated in all experiments and coronary flow was measured in Langendorff preparations. In the present experiments, no cardioprotective effects of Crataegus oxyacantha could be detected, neither in the heart in situ nor in the Langendorff preparations. Although the ischemic areas were identical, arrhythmias occurred even earlier in the Crataegus collectives than in the controls. Also the number and duration of ischemia and reperfusion induced arrhythmias tended to occur longer and more frequently in the Crataegus collectives, whilst coronary flow remained unchanged. The phenomenon that Crataegus rather aggravates than prevents arrhythmias may be reduced to a Crataegus induced increase in intracellular Ca(2+)-concentration proven true for the positive inotropic effects of Crataegus.

PMID: 11215322 [PubMed - indexed for MEDLINE]

 

Am Heart J. 2000 Mar;139(3):522-8.

 

Magnesium supplementation in the prevention of arrhythmias in pediatric patients undergoing surgery for congenital heart defects.

Dorman BH, Sade RM, Burnette JS, Wiles HB, Pinosky ML, Reeves ST, Bond BR, Spinale FG.

Department of Anesthesia and Perioperative Medicine, Medical University of South Carolina, South Carolina, USA. dormanhb@musc.edu

BACKGROUND: The efficacy of magnesium in the prevention of arrhythmias in pediatric patients after heart surgery remains unknown. Therefore we prospectively examined the effect of magnesium treatment on the incidence of postoperative arrhythmias in pediatric patients undergoing surgical repair of congenital heart defects. METHODS AND RESULTS: Twenty-eight pediatric patients undergoing heart surgery with cardiopulmonary bypass were prospectively, randomly assigned in a double-blind fashion to receive intravenous magnesium (magnesium group, n = 13; 30 mg/kg) or saline (placebo group, n = 15) immediately after cessation of cardiopulmonary bypass. Magnesium, potassium, and calcium levels were measured at defined intervals during surgery and 24 hours after surgery. Continuous electrocardiographic documentation by Holter monitor was performed for 24 hours after surgery. Magnesium levels were significantly decreased below the normal reference range for patients in the placebo group compared with the magnesium group on arrival in the intensive care unit and for 20 hours after surgery. Magnesium levels remained in the normal range for patients in the magnesium group after magnesium supplementation. In 4 patients in the placebo group (27%), junctional ectopic tachycardia developed within the initial 20 hours in the intensive care unit. No junctional ectopic tachycardia was observed in the magnesium group (P =.026). CONCLUSIONS: Although this study was originally targeted to include 100 patients, the protocol was terminated because of the unacceptable incidence of hemodynamically significant junctional ectopic tachycardia that was present in the placebo group. Thus low magnesium levels in pediatric patients undergoing heart surgery are associated with an increased incidence of junctional ectopic tachycardia in the immediate postoperative period.

Publication Types:

Clinical Trial

Randomized Controlled Trial

PMID: 10689268 [PubMed - indexed for MEDLINE]

 

Psychosom Med. 1999 Nov-Dec;61(6):812-21.

 

Zazen and cardiac variability.

Lehrer P, Sasaki Y, Saito Y.

Department of Psychiatry, Robert Wood Johnson Medical School, University of Medicine and Dentistry of New Jersey, Piscataway 08854-5635, USA.

OBJECTIVE: This study examined the effects of "tanden breathing" by Zen practitioners on cardiac variability. Tanden breathing involves slow breathing into the lower abdomen. METHODS: Eleven Zen practitioners, six Rinzai and five Soto, were each studied during 20 minutes of tanden breathing, preceded and followed by 5-minute periods of quiet sitting. During this time, we measured heart rate and respiration rate. RESULTS: For most subjects, respiration rates fell to within the frequency range of 0.05 to 0.15 Hz during tanden breathing. Heart rate variability significantly increased within this low-frequency range but decreased in the high-frequency range (0.14-0.4 Hz), reflecting a shift of respiratory sinus arrhythmia from high-frequency to slower waves. Rinzai practitioners breathed at a slower rate and showed a higher amplitude of low-frequency heart rate waves than observed among Soto Zen participants. One Rinzai master breathed approximately once per minute and showed an increase in very-low-frequency waves (<0.05 Hz). Total amplitude of heart rate oscillations (across frequency spectra) also increased. More experienced Zen practitioners had frequent heart rhythm irregularities during and after the nadir of heart rate oscillations (ie, during inhalation). CONCLUSIONS: These data are consistent with the theory that increased oscillation amplitude during slow breathing is caused by resonance between cardiac variability caused by respiration and that produced by physiological processes underlying slower rhythms. The rhythm irregularities during inhalation may be related to inhibition of vagal modulation during the cardioacceleratory phase. It is not known whether they reflect cardiopathology.

PMID: 10593633 [PubMed - indexed for MEDLINE]

 

Conscious Cogn. 1999 Sep;8(3):302-18.

 

Autonomic and EEG patterns during eyes-closed rest and transcendental meditation (TM) practice: the basis for a neural model of TM practice.

Travis F, Wallace RK.

Maharishi University of Management, Fairfield, Iowa 52557, USA. Ftravis@mum.edu

In this single-blind within-subject study, autonomic and EEG variables were compared during 10-min, order-balanced eyes-closed rest and Transcendental Meditation (TM) sessions. TM sessions were distinguished by (1) lower breath rates, (2) lower skin conductance levels, (3) higher respiratory sinus arrhythmia levels, and (4) higher alpha anterior-posterior and frontal EEG coherence. Alpha power was not significantly different between conditions. These results were seen in the first minute and were maintained throughout the 10-min sessions. TM practice appears to (1) lead to a state fundamentally different than eyes-closed rest; (2) result in a cascade of events in the central and autonomic nervous systems, leading to a rapid change in state (within a minute) that was maintained throughout the TM session; and (3) be best distinguished from other conditions through autonomic and EEG alpha coherence patterns rather than alpha power. Two neural networks that may mediate these effects are suggested. The rapid shift in physiological functioning within the first minute might be mediated by a "neural switch" in prefrontal areas inhibiting activity in specific and nonspecific thalamocortical circuits. The resulting "restfully alert" state might be sustained by a basal ganglia-corticothalamic threshold regulation mechanism automatically maintaining lower levels of cortical excitability. Copyright 1999 Academic Press.

PMID: 10487785 [PubMed - indexed for MEDLINE]

J Am Coll Cardiol. 1999 Feb;33(2):327-32.

 

Auditory stimuli as a trigger for arrhythmic events differentiate HERG-related (LQTS2) patients from KVLQT1-related patients (LQTS1).

Wilde AA, Jongbloed RJ, Doevendans PA, Duren DR, Hauer RN, van Langen IM, van Tintelen JP, Smeets HJ, Meyer H, Geelen JL.

Department of Clinical and Experimental Cardiology, Academic Medical Center, Amsterdam, The Netherlands.

OBJECTIVE: This study was performed to identify a possible relationship between genotype and phenotype in the congenital familial long QT syndrome (cLQTS). BACKGROUND: The cLQTS, which occurs as an autosomal dominant or recessive trait, is characterized by QT-interval prolongation on the electrocardiogram and torsade de pointes arrhythmias, which may give rise to recurrent syncope or sudden cardiac death. Precipitators for cardiac events are exercise or emotion and occasionally acoustic stimuli. METHODS: The trigger for cardiac events (syncope, documented cardiac arrhythmias, sudden cardiac death) was analyzed in 11 families with a familial LQTS and a determined genotype. RESULTS: The families were subdivided in KVLQT1-related families (LQTS1, n = 5) and HERG (human ether-a-gogo-related gene)-related families (LQTS2, n = 6) based on single-strand conformation polymorphism analysis and sequencing. Whereas exercise-related cardiac events dominate the clinical picture of LQTS1 patients, auditory stimuli as a trigger for arrhythmic events were only seen in LQTS2 patients. CONCLUSIONS: Arrhythmic events triggered by auditory stimuli may differentiate LQTS2 from LQTS1 patients.

PMID: 9973011 [PubMed - indexed for MEDLINE]

Psychophysiology. 1992 Nov;29(6):698-711.

 

Cardiac autonomic mechanisms associated with borderline hypertension under varying behavioral demands: evidence for attenuated parasympathetic tone but not for enhanced beta-adrenergic activity.

Grossman P, Brinkman A, de Vries J.

Department of Psychophysiology, Free University of Amsterdam.

Elevated blood pressure in psychophysiological studies of borderline hypertension is frequently attributed to the effects of increased sympathetic tone, and with few exceptions, the potential parasympathetic contributions have not been considered. Furthermore, of the investigations that have addressed vagal influences upon blood pressure, most have employed invasive pharmacological assessment of parasympathetic tone. In this study, cardiac parasympathetic and beta-adrenergic influences in borderline hypertension were evaluated noninvasively employing respiratory sinus arrhythmia as a vagal index and preejection period as a sympathetic index of cardiac functioning. Subjects were 30 borderline hypertensive and 23 normotensive males (age range, 24-45 years). The ECG, blood pressure, impedance cardiography, and respiration were measured during two baselines (initial and post-task), a memory-comparison reaction time task, the cold pressor, and CO2-rebreathing. Results indicated tonic differences between groups in all cardiovascular variables across tasks, with the exception of pre-ejection period, which showed no group effects at all. Hypertensives additionally manifested somewhat heightened systolic blood pressure reactivity and attenuated cardiac parasympathetic responsivity to specific tasks. Our findings provide no support for an exaggerated cardiac beta-adrenergic tonic level or reactivity in borderline hypertensives. On the other hand, the consistently lower magnitude of respiratory sinus arrhythmia in our hypertensives suggests that reduced parasympathetic control may be involved in the pathophysiology of hypertension.

PMID: 1334272 [PubMed - indexed for MEDLINE]

 

Behav Med. 1989 Fall;15(3):111-7.

 

The efficacy of the relaxation response in preparing for cardiac surgery.

Leserman J, Stuart EM, Mamish ME, Benson H.

Department of Medicine, New England Deaconess Hospital, Harvard Medical School, Boston.

This study evaluated the efficacy of the relaxation response on the post-operative recovery of 27 cardiac surgery patients randomly assigned to one of two groups. Thirteen experimental group patients received educational information and practiced eliciting the relaxation response before and after surgery. The 14 patients in the control group received only information. Experimental and control groups were compared before and after surgery on both physiological and psychological recovery variables. There were no initial differences between experimental and control groups on demographic, physiological, and most psychological variables. The experimental group had lower incidence of postoperative supraventricular tachycardia (SVT) than the control group (p = .04) despite having had the same occurrence previously. Experimental and control groups did not significantly differ over the course of study on any other physiological variables. Patients practicing the relaxation response had greater decreases in psychological tension (p = .04) and anger (p = .04) than those who received only educational information. The decreases in psychological tension may have been a result of regression to the mean because the experimental group started with elevated tension relative to the control group (p = .04). We conclude that practicing the relaxation response before and after surgery may reduce SVT, tension, and anger.

Publication Types:

Clinical Trial

Randomized Controlled Trial

PMID: 2676027 [PubMed - indexed for MEDLINE]

Am J Med. 1985 Apr;78(4):645-54.

 

Carotid sinus massage. Its diagnostic and therapeutic value in arrhythmias.

Schweitzer P, Teichholz LE.

Carotid sinus massage is a simple bedside maneuver that helps to clarify the type and sometimes also the mechanism of different rhythm disturbances. The major indication for carotid sinus massage is the diagnosis of tachyarrhythmias in which the atrial activity is either absent or intermittently present. Carotid sinus massage is also useful in some patients with normal heart rates; increased vagal tone may normalize a bundle branch block or localize the site of type I second-degree atrioventricular block and can be used for evaluation of the sensing function of permanent pacemakers. Carotid sinus massage is also an important diagnostic procedure in patients with suspected hypersensitivity of the carotid sinus. Massage of the carotid sinus is contraindicated in patients with diseased carotid arteries because of the risk of cerebrovascular accident. In rare instances, carotid sinus massage may initiate ventricular tachycardia.

PMID: 3985038 [PubMed - indexed for MEDLINE]