Comparison between the double-syringe and the single-syringe techniques of adenosine administration for terminating supraventricular tachycardia: A pilot, randomized controlled trial

BACKGROUND

Adenosine has been recommended as a first-line treatment for stable supraventricular tachycardia (SVT). Standard guidelines recommend 6-mg of adenosine administered intravenously (IV) with an immediate 20-ml IV bolus of normal saline solution (NSS; double syringe technique [DST]). However, a newly proposed single-syringe technique (SST), in which adenosine is diluted with an up to 20 ml IV bolus of NSS, was found to be beneficial.

HYPOTHESIS

We hypothesized that the SST was noninferior to the DST for terminating stable SVT.

METHODS

A pilot multicenter, single-blind, randomized controlled study was conducted at nine hospitals in north and northeast Thailand. Thirty patients who were diagnosed with stable SVT were randomized into two groups of 15, with one receiving adenosine via the DST and the other via the SST. We examined SVT termination, the average successful dose, and the complication rate of each group. Analyses were based on the intention-to-treat principle.

RESULT

The termination rate was 93.3% in the DST and 100% in the SST group (p = 1.000), and the success rate of the first 6-mg dose of adenosine was 73.3% and 80%, respectively (p = 1.000). The total administered dose was 8.6 ± 5.1 mg in the DST group and 7.6 ± 4.5 mg in the SST group (p = .608). No complications were found in either group.

CONCLUSIONS

The SST was non-inferior to the DST for termination of SVT. However, a further definitive study with a larger sample size is required.

Overview of drug treatment for paroxysmal supraventricular tachycardia in Taiwan emergency departments: Adenosine using trend from 2000 to 2012

BACKGROUND

Before 2010, guidelines recommended adenosine 6, 12, and a repeat dose of 12 mg for paroxysmal supraventricular tachycardia (PSVT). After 2010, these doses were reduced to two. This study aims to outline adenosine using trend from 2000 to 2012 in Taiwan emergency departments (EDs).

METHODS

This was an ecological study. PSVT were drawn from one million individuals of the National Health Insurance Database. The χ² test was used to determine an association between different adenosine doses and other antiarrhythmic drugs (OADs), including verapamil, diltiazem, amiodarone, digoxin, and labetalol.

RESULTS

There were 3361 PSVT visits from 2000 to 2012; 834 (24.8%) did not receive an antiarrhythmic drug, and 2527 (75.2%) did, either adenosine with/without OADs or OADs alone. The use of an OAD was significantly different between the adenosine 6-18 mg and 19 + mg groups.

CONCLUSIONS

Most PSVT episodes converted with adenosine within 18 mg, and the success conversion rate was 62.2%. It could be up to 65.2% if they received more. Of the patients who did not have their PSVT reverted with< 18 mg, 37.8% could have been successfully treated with more doses. The necessity of using the 3rd dose of adenosine is needed to be further explored.

The reverse vagal manoeuvre: A new tool for treatment of supraventricular tachycardia?

Supraventricular tachycardia is a common cardiac arrhytmia with recurrent episodes. The rapid resolution of supraventricular tachycardia remains a challenge. Vagal manoeuvres are simple and non-invasive but yield positive results in less than half the cases. Currently, the modified Valsalva manoeuvre appears to be the most effective technique. We have tested the effectiveness of the reverse Valsalva manoeuvre without swallowing as new vagal manoeuvre for the treatment of supraventricular tachycardia. This new technique is easy to perform and can be carried out alone by the patient. We report in this series 11 cases of supraventricular tachycardia, 10 of which were effectively reduced after the completion of the reverse Valsava manoeuvre. The very encouraging results of this series of cases will have to be quickly evaluated by a randomised controlled trial. This new technique, which is simple to learn and carry out, could be easily taught throughout the world, including in regions with few health-care resources.

AH jump duration is associated with elimination of slow pathway during ablation of atrioventricular nodal reentrant tachycardia

Introduction

Ablating the slow pathway (SP) is the superior treatment for atrioventricular nodal reentrant tachycardia (AVNRT) with a low complication rate. However, the ablation of the SP could result in either complete elimination or modification of the SP. We aimed to investigate whether the duration of AH jump pre-ablation associated with the outcome of elimination of SP.

Methods

We included 56 patients with typical AVNRT (slow-fast), 20 males and 36 females, aged 44.2 ± 15.1 years. Slow pathway ablation was performed using classical approach. Univariate and multivariate analysis was performed for potential predictors of SP elimination.

Results

Typical AVNRT was inducible in all patients. Post-ablation, non-inducibility of AVNRT was obtained in all 56 (100%) patients, with SP elimination in 33 (61%) patients and SP modification in 23 (39%) patients. Patients with SP elimination had significantly longer AH jump than patients with SP modification. Cox regression analysis showed that AH jump duration was the independent predictor of SP elimination, in which every 20 ms increase in AH jump duration was associated with 1.30 higher rate of SP elimination. Furthermore, ROC curve analysis indicated that the AH jump duration of ≥100 ms had 6.14 times higher probability for complete elimination of the SP with a sensitivity of 79%, specificity of 70%, PPV of 79% and NPV of 70%.

Conclusions

AH jump duration pre-ablation is associated with complete elimination of slow pathway during AVNRT ablation.

Next-generation sequencing of AV nodal reentrant tachycardia patients identifies broad spectrum of variants in ion channel genes

Atrioventricular nodal reentry tachycardia (AVNRT) is the most common form of regular paroxysmal supraventricular tachycardia. This arrhythmia affects women twice as frequently as men, and is often diagnosed in patients <40 years of age. Familial clustering, early onset of symptoms and lack of structural anomaly indicate involvement of genetic factors in AVNRT pathophysiology. We hypothesized that AVNRT patients have a high prevalence of variants in genes that are highly expressed in the atrioventricular conduction axis of the heart and potentially involved in arrhythmic diseases. Next-generation sequencing of 67 genes was applied to the DNA profile of 298 AVNRT patients and 10 AVNRT family members using HaloPlex Target Enrichment System. In total, we identified 229 variants in 60 genes; 215 missenses, four frame shifts, four codon deletions, three missense and splice sites, two stop-gain variants, and one start-lost variant. Sixty-five of these were not present in the Exome Aggregation Consortium (ExAC) database. Furthermore, we report two AVNRT families with co-segregating variants. Seventy-five of 284 AVNRT patients (26.4%) and three family members to different AVNRT probands had one or more variants in genes affecting the sodium handling. Fifty-four out of 284 AVNRT patients (19.0%) had variants in genes affecting the calcium handling of the heart. We furthermore find a large proportion of variants in the HCN1-4 genes. We did not detect a significant enrichment of rare variants in the tested genes. This could be an indication that AVNRT might be an electrical arrhythmic disease with abnormal sodium and calcium handling.

Adenosine versus intravenous calcium channel antagonists for supraventricular tachycardia

BACKGROUND

People with supraventricular tachycardia (SVT) frequently are symptomatic and present to the emergency department for treatment. Although vagal manoeuvres may terminate SVT, they often fail, and subsequently adenosine or calcium channel antagonists (CCAs) are administered. Both are known to be effective, but both have a significant side effect profile. This is an update of a Cochrane review previously published in 2006.

OBJECTIVES

To review all randomised controlled trials (RCTs) that compare effects of adenosine versus CCAs in terminating SVT.

SEARCH METHODS

We identified studies by searching CENTRAL, MEDLINE, Embase, and two trial registers in July 2017. We checked bibliographies of identified studies and applied no language restrictions.

SELECTION CRITERIA

We planned to include all RCTs that compare adenosine versus a CCA for patients of any age presenting with SVT.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane. Two review authors independently checked results of searches to identify relevant studies and resolved differences by discussion with a third review author. At least two review authors independently assessed each included study and extracted study data. We entered extracted data into Review Manager 5. Primary outcomes were rate of reversion to sinus rhythm and major adverse effects of adenosine and CCAs. Secondary outcomes were rate of recurrence, time to reversion, and minor adverse outcomes. We measured outcomes by calculating odds ratios (ORs) and assessed the quality of primary outcomes using the GRADE approach through the GRADEproGDT website.

MAIN RESULTS

We identified two new studies for inclusion in the review update; the review now includes seven trials with 622 participants who presented to an emergency department with SVT. All included studies were RCTs, but only three described the randomisation process, and none had blinded participants, personnel, or outcome assessors to the intervention given. Moderate-quality evidence shows no differences in the number of people reverting to sinus rhythm who were treated with adenosine or CCA (89.7% vs 92.9%; OR 1.51, 95% confidence interval (CI) 0.85 to 2.68; participants = 622; studies = 7; I² = 36%). Low-quality evidence suggests no appreciable differences in major adverse event rates between CCAs and adenosine. Researchers reported only one case of hypotension in the CCA group and none in the adenosine group (0.66% vs 0%; OR 3.09, 95% CI 0.12 to 76.71; participants = 306; studies = 3; I² = 0%). Included trials did not report length of stay in hospital nor patient satisfaction.

AUTHORS' CONCLUSIONS

Moderate-quality evidence shows no differences in effects of adenosine and calcium channel antagonists for treatment of SVT on reverting to sinus rhythm, and low-quality evidence suggests no appreciable differences in the incidence of hypotension. A study comparing patient experiences and prospectively studied adverse events would provide evidence on which treatment is preferable for management of SVT.

Usefulness of laboratory and radiological investigations in the management of supraventricular tachycardia

OBJECTIVE

Although ED patients presenting with supraventricular tachycardia (SVT) are commonly investigated, the value of these investigations has been questioned. We aimed to determine the frequency and utility of investigations in patients with SVT.

METHODS

We undertook an explicit retrospective medical record audit of patients with SVT who presented to a single ED (January 2004 to June 2014). Data on demographics, presenting complaints, investigations and outcomes were extracted. The outcomes were nature and utility of investigations.

RESULTS

A total of 633 patients were enrolled (mean [SD] age 55.4 [17.7] years, 62% female). Laboratory investigations were common: electrolytes (83.7% of patients), full blood count (81.2%), magnesium (57.5%), calcium (39.3%) and thyroid function (30.3%). These investigations revealed many mildly abnormal results but resulted in electrolyte supplementation in only 19 patients: eight with mild hypokalaemia (potassium 3.0-3.5 mmol/L) and 11 with mild hypomagnesia (magnesium 0.49-1.1 mmol/L). Troponin was ordered for 302 (47.7%) patients, many of whom had no history or risk factors for cardiac disease, or ischaemic symptoms associated with their SVT. The troponin was normal, mildly and moderately elevated in 65.2, 24.5 and 10.2% of cases, respectively. Only seven (1.1%) patients were diagnosed with acute myocardial ischemia. Although 190 (30.0%) patients had a chest X-ray (CXR), it was normal in 78.4% of cases. All CXR abnormalities were incidental and not relevant to the immediate ED management.

CONCLUSION

Patients with uncomplicated SVT are over-investigated. Guidelines for ED SVT investigation are recommended. Further research is recommended to determine the indications for each investigation in the setting of SVT.

A model for priority setting of health technology assessment: the experience of AHP-TOPSIS combination approach

BACKGROUND

In recent times, the use of health technologies in the diagnosis and treatment of diseases experienced considerable and accelerated growth. The goal of the present study was to describe the designated pilot MCDM (Multiple Criteria Decision Making) model for priority setting of health technology assessment in Iran.

METHODS

Relevant articles were sought and retrieved from the most appropriate medical databases, including the Cochrane Library, PubMed and Scopus via three separate search strategies, using MESH and free text until March, 2015. Retrieved criteria were questioned from health technology assessment experts in two rounds and the relative weight for valid criteria was finally obtained from paired wise comparison method. After extraction of relative weights based on the aforementioned procedure, TOPSIS (The Technique for Order of Preference by Similarity to Ideal Solution) priority setting model was designed. The stated model was applied for assessing three technologies (adenosine, tissue plasminogen activator and mechanical thrombectomy) which were available for projects call of Iranian health technology assessment department in order to determine applicability of the model for practical purpose.

RESULTS

Nine criteria, including efficiency/effectiveness, safety, population size, vulnerable population size, availability of alternative technologies, cost effectiveness in other countries, budget impact, financial protection, quality of evidence, were extracted by the Iranian health technology assessment experts. The relative weights of these criteria were as follows 0.12, 0.2, 0.06, 0.08, 0.08, 0.13, 0.08, 0.09, and 0.15, respectively. Finally TOPSIS pilot model was designed by three health technologies and nine criteria relative weights. Results showed that, the applicability of the stated model was suitable and as the pilot testing, tissue plasminogen activator was the first priority, adenosine was second and mechanical thrombectomy was third for performing health technology assessment by the Iranian ministry of health and medical education.

CONCLUSION

According to the results of this study, this model with nine effective criteria and their relative weights and in combination with TOPSIS approach could be used with suitable applicability by health technology assessment department in deputy of curative affairs and food and drug organization for determination of research priorities in health technology assessment.

Clinical Experience with Diltiazem in the Treatment of Cardiovascular Diseases

Abstract

Cardiovascular diseases are the leading cause of death in the world. Coronary artery diseases, atrial fibrillation or hypertensive heart disease, are among the most important cardiovascular disorders. Hypertension represents a significant risk factor for cardiovascular mortality; thus, control of high blood pressure has become a priority to prevent major complications. Although the choice of drugs for treating hypertension remains controversial, extensive clinical evidences point to calcium channel blockers as first-line agents. Diltiazem, a non-dihydropyridine calcium channel blocker, is an effective and safe antihypertensive drug, alone or in combination with other agents. Diltiazem lowers myocardial oxygen demand through a reduction in heart rate, blood pressure, and cardiac contractility, representing also a good alternative for the treatment of stable chronic angina. Furthermore, diltiazem reduces conduction in atrioventricular node, which is also useful for heart rate control in patients with atrial fibrillation. In this review, clinical experts highlight studies on diltiazem effectiveness and safety for the treatment of several cardiovascular diseases and make evidence-based recommendations regarding the management of diltiazem in the clinical practice.

Funding

Lacer Spain.

Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia

BACKGROUND

People with the cardiac arrhythmia supraventricular tachycardia (SVT) frequently present to clinicians in the prehospital and emergency medicine settings. Restoring sinus rhythm by terminating the SVT involves increasing the refractoriness of atrioventricular nodal tissue within the myocardium by means of vagal manoeuvres, pharmacological agents, or electrical cardioversion. A commonly used first-line technique to restore the normal sinus rhythm (reversion) is the Valsalva Manoeuvre (VM). This is a non-invasive means of increasing myocardial refractoriness by increasing intrathoracic pressure for a brief period, thus stimulating baroreceptor activity in the aortic arch and carotid bodies, resulting in increased parasympathetic (vagus nerve) tone.

OBJECTIVES

To assess the evidence of effectiveness of the VM in terminating SVT.

SEARCH METHODS

We updated the electronic searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2014, Issue 7); MEDLINE Ovid (1946 to August week 3, 2014); EMBASE Classic and EMBASE Ovid (1947 to 27 August 2014); Web of Science (1970 to 27 August 2014); and BIOSIS Previews (1969 to 22 August 2014). We also checked trials registries, the Index to Theses, and the bibliographies of all relevant publications identified by these strategies.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that examined the effectiveness of VM in terminating SVT.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted the data using a standardised form. We assessed each trial for internal validity, resolving any differences by discussion. We then extracted and entered data into Review Manager 5.

MAIN RESULTS

In this update, we did not identify any new RCT studies for inclusion. We identified two RCT studies as ongoing that we are likely to include in future updates. Accordingly, our results are unchanged and include three RCTs with a total of 316 participants. All three studies compared the effectiveness of VM in reverting SVT with that of other vagal manoeuvres in a cross-over design. Two studies induced SVT within a controlled laboratory environment. Participants had ceased all medications prior to engaging in these studies. The third study reported on people presenting to a hospital emergency department with an episode of SVT. These participants were not controlled for medications or other factors prior to intervention.The two laboratory studies demonstrated reversion rates of 45.9% and 54.3%, whilst the clinical study demonstrated reversion success of 19.4%. This discrepancy may be due to methodological differences between studies, the effect of induced SVT versus spontaneous episodic SVT, and participant factors such as medications and comorbidities. We were unable to assess any of these factors, or adverse effects, further, since they were either not described in enough detail or not reported at all.Statistical pooling was not possible due to heterogeneity between the included studies.

AUTHORS' CONCLUSIONS

We did not find sufficient evidence to support or refute the effectiveness of VM for termination of SVT. Further research is needed, and this research should include a standardised approach to performance technique and methodology.

Position paper on the importance of psychosocial factors in cardiology: Update 2013

Background: The rapid progress of psychosomatic research in cardiology and also the increasing impact of psychosocial issues in the clinical daily routine have prompted the Clinical Commission of the German Heart Society (DGK) to agree to an update of the first state of the art paper on this issue which was originally released in 2008.

Methods: The circle of experts was increased, general aspects were implemented and the state of the art was updated. Particular emphasis was dedicated to coronary heart diseases (CHD), heart rhythm diseases and heart failure because to date the evidence-based clinical knowledge is most advanced in these particular areas. Differences between men and women and over the life span were considered in the recommendations as were influences of cognitive capability and the interactive and synergistic impact of classical somatic risk factors on the affective comorbidity in heart disease patients.

Results: A IA recommendation (recommendation grade I and evidence grade A) was given for the need to consider psychosocial risk factors in the estimation of coronary risks as etiological and prognostic risk factors. Furthermore, for the recommendation to routinely integrate psychosocial patient management into the care of heart surgery patients because in these patients, comorbid affective disorders (e.g. depression, anxiety and post-traumatic stress disorder) are highly prevalent and often have a malignant prognosis. A IB recommendation was given for the treatment of psychosocial risk factors aiming to prevent the onset of CHD, particularly if the psychosocial risk factor is harmful in itself (e.g. depression) or constrains the treatment of the somatic risk factors. Patients with acute and chronic CHD should be offered anti-depressive medication if these patients suffer from medium to severe states of depression and in this case medication with selective reuptake inhibitors should be given. In the long-term course of treatment with implanted cardioverter defibrillators (ICDs) a subjective health technology assessment is warranted. In particular, the likelihood of affective comorbidities and the onset of psychological crises should be carefully considered.

Conclusions: The present state of the art paper presents an update of current empirical evidence in psychocardiology. The paper provides evidence-based recommendations for the integration of psychosocial factors into cardiological practice and highlights areas of high priority. The evidence for estimating the efficiency for psychotherapeutic and psychopharmacological interventions has increased substantially since the first release of the policy document but is, however, still weak. There remains an urgent need to establish curricula for physician competence in psychodiagnosis, communication and referral to ensure that current psychocardiac knowledge is translated into the daily routine.

Catheter ablation for supraventricular tachycardias: contemporary issues

The treatment of cardiac arrhythmias has evolved significantly over the last 30 years. Understanding of arrhythmia mechanisms has led to pharmacologic therapies, surgical interventions and the widely used percutaneous catheter ablation techniques. The focus of this review is centered on the current catheter ablation therapies available for supraventricular tachycardia. We will discuss current management strategies including challenges when considering catheter ablation therapy for management of supraventricular tachycardias: atrioventricular nodal reentrant tachycardia, atrioventricular reentrant tachycardia utilizing an accessory pathway, atrial tachycardia and atrial flutter. Selected contemporary issues related to supraventricular tachycardia physiology, ablation approaches and ablation outcomes and complications will be discussed. Future goals for electrophysiologists are to continue to improve procedural safety and efficiency, while maintaining the impressive success rates that have been achieved.

Dexmedetomidine controls supraventricular tachycardia following cardiac surgery in a child

Dexmedetomidine is an α2-adrenergic agonist which initially received US Food and Drug Administration (FDA) approval in the United States in 1999 for the sedation of adults during mechanical ventilation and then in 2009 for monitored anesthesia care. Although generally viewed as an adverse effect, bradycardia and the negative chronotropic effects may be beneficial in certain patient populations and have occasionally been used as a therapeutic maneuver. We present a case summary describing intraoperative and postoperative use of dexmedetomidine to treat and control supraventricular tachycardia in a 5-year-old boy undergoing surgical repair of a large atrial septal defect. The specific effects of dexmedetomidine on the cardiac conduction system are reviewed and previous reports of its use as a therapeutic agent for the treatment of perioperative tachyarrhythmias are discussed.

Effectiveness of the Valsalva Manoeuvre for reversion of supraventricular tachycardia

BACKGROUND

Patients with the cardiac arrhythmia supraventricular tachycardia (SVT) frequently present to clinicians in the prehospital and emergency medicine settings. Restoring sinus rhythm by terminating the SVT involves increasing the refractoriness of AV nodal tissue within the myocardium by means of vagal manoeuvres, pharmacological agents or electrical cardioversion. A commonly used first-line technique to restore the normal sinus rhythm (reversion) is the Valsalva Manoeuvre (VM). This is a non-invasive means of increasing myocardial refractoriness by increasing intrathoracic pressure for a brief period, thus stimulating baroreceptor activity in the aortic arch and carotid bodies, resulting in increased parasympathetic (vagus nerve) tone.

OBJECTIVES

To assess the evidence of effectiveness of the Valsalva Manoeuvre in terminating supraventricular tachycardia.

SEARCH METHODS

We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (Issue 1 of 12, 2012); MEDLINE Ovid (1946 to January 2012); EMBASE Ovid (1947 to January 2012); Web of Science (1970 to 27 January 2012); and BIOSIS Previews (1969 to 27 January 2012). Trials registries, the Index to Theses and the bibliographies of all relevant publications identified by these strategies were also checked.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs) that examined the effectiveness of the Valsalva Manoeuvre in terminating SVT.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted the data using a standardised form. Each trial was assessed for internal validity with differences resolved by discussion. Data were then extracted and entered into Review Manager 5.1 (RevMan).

MAIN RESULTS

We identified three randomised controlled trials including 316 participants. All three studies compared the effectiveness of VM in reverting SVT with that of other vagal manoeuvres in a cross-over design. Two studies induced SVT within a controlled laboratory environment. Participants had ceased all medications prior to engaging in these studies. The third study reported on patients presenting to a hospital emergency department with an episode of SVT. These patients were not controlled for medications or other factors prior to intervention.The two laboratory studies demonstrated reversion rates of 45.9% and 54.3%, whilst the clinical study demonstrated reversion success of 19.4%. This discrepancy may be due to methodological differences between studies, the effect of induced SVT versus spontaneous episodic SVT, and participant factors such as medications and comorbidities. We were unable to assess any of these factors further, nor adverse effects, since they were either not described in enough detail or not reported at all.Statistical pooling was not possible due to heterogeneity between the included studies.

AUTHORS' CONCLUSIONS

We did not find sufficient evidence to support or refute the effectiveness of the Valsalva Manoeuvre for termination of SVT. Further research is needed and this should include a standardised approach to performance technique and methodology.

Aqueous fraction from Costus spiralis (Jacq.) Roscoe leaf reduces contractility by impairing the calcium inward current in the mammalian myocardium

ETHNOPHARMACOLOGICAL RELEVANCE

Brazilian folk medicine uses infusion of Costus spiralis leaf to help people to treat arterial hypertension and syndromes of cardiac hyperexcitability.

AIM OF THE STUDY

Evaluate the aqueous fraction (AqF) effect on atrial contractility and investigate its mechanism of action.

MATERIALS AND METHODS

The AqF effect on the cardiac contractility was studied on isolated electrically driven guinea pig left atria. Atropine and tetraethylammonium (TEA) were employed to investigate whether potassium contributes for the inotropic mechanism of the AqF. The role of calcium in this effect was also studied. This was done by analysing the AqF effect on the Bowditch's phenomenon, as well as by studying whether it could interfere with the concentration-effect curve for CaCl(2), isoproterenol, and BAY K8644. Mice isolated cardiomyocytes were submitted to a whole-cell patch-clamp technique in order to evaluate whether the L-type calcium current participates on the AqF effect. Furthermore, the intracellular calcium transient was studied by confocal fluorescence microscopy.

RESULTS

AqF depressed the atrial contractile force. It was the most potent fraction from C. spiralis leaf (EC(50)=305 ± 41 mg/l) (crude extract: EC(50)=712 ± 41; ethyl acetate: EC(50)=788 ± 121; chloroform: EC(50)=8,948 ± 1,346 mg/l). Sodium and potassium content in the AqF was 0.15 mM and 1.91 mM, respectively. Phytochemical analysis revealed phenols, tannins, flavones, xanthones, flavonoids, flavonols, flavononols, flavonones, and saponins. Experiments with atropine and TEA showed that potassium does not participate of the inotropic mechanism of AqF. However, this fraction decreased the force overshoot characteristic of the Bowditch's phenomenon, and shifted the concentration-response curve for CaCl(2) (EC(50) from 1.12 ± 0.07 to 7.23 ± 0.47 mM) indicating that calcium currents participate on its mechanism of action. Results obtained with isoproterenol (1-1,000 pM) and BAY K8644 (5-2000nM) showed that AqF abolished the inotropic effect of these substances. On cardiomyocytes, 48mg/l AqF reduced (∼23%) the L-type calcium current density from -6.3 ± 0.3 to -4.9 ± 0.2 A/F (n=5 cells, p<0.05) and reduced the intracellular calcium transient (∼20%, 4.7 ± 1.2 a.u., n=42 cells to 3.7 ± 1.00 a.u., n=35 cells, p<0.05). However, the decay time of the fluorescence was not changed (control: 860 ± 32 ms, n=42 cells; AqF: 876 ± 26 ms, n=35 cells, p>0.05).

CONCLUSIONS

The AqF of C. spiralis leaf depresses myocardial contractility by reducing the L-type calcium current and by decreasing the intracellular calcium transient. Despite the lack of data on the therapeutic dose of AqF used in folk medicine, our results support, at least in part, the traditional use of this plant to treat cardiac disorders.

Carotid body function in aged rats: responses to hypoxia, ischemia, dopamine, and adenosine

The carotid body (CB) is the main arterial chemoreceptor with a low threshold to hypoxia. CB activity is augmented by A(2)-adenosine receptors stimulation and attenuated by D(2)-dopamine receptors. The effect of aging on ventilatory responses mediated by the CB to hypoxia, ischemia, and to adenosine and dopamine administration is almost unknown. This study aims to investigate the ventilatory response to ischemia and to adenosine, dopamine, and their antagonists in old rats, as well as the effect of hypoxia on adenosine 3',5'-cyclic monophosphate (cAMP) accumulation in the aged CB. In vivo experiments were performed on young and aged rats anesthetized with pentobarbitone and breathing spontaneously. CB ischemia was induced by bilateral common carotid occlusions. cAMP content was measured in CB incubated with different oxygen concentrations. Hyperoxia caused a decrease in cAMP in the CB at all ages, but no differences were found between normoxia and hypoxia or between young and old animals. The endogenous dopaminergic inhibitory tonus is slightly reduced. However, both the ventilation decrease caused by exogenous dopamine and the increase mediated by A(2A)-adenosine receptors are not impaired in aged animals. The bradycardia induced by adenosine is attenuated in old rats. The CB's peripheral control of ventilation is preserved during aging. Concerns have also arisen regarding the clinical usage of adenosine to revert supraventricular tachycardia and the use of dopamine in critical care situations involving elderly people.

Adenosine modulates Toll-like receptor function: basic mechanisms and translational opportunities

Adenosine is an endogenous purine metabolite whose concentration in human blood plasma rises from nanomolar to micromolar concentrations during the inflammatory process. Leukocytes express seven-transmembrane adenosine receptors whose engagement modulates Toll-like receptor-mediated cytokine responses, in part via modulation of intracellular cyclic adenosine monophosphate. Adenosine analogs are used clinically to treat arrhythmias and apnea of prematurity. Herein, we consider the potential of adenosine analogs as innate immune response modifiers to prevent and/or treat infection.

[Psychosomatic aspects of cardiac arrhythmias]

Emotional stress facilitates the occurrence of cardiac arrhythmias including sudden cardiac death. The prevalence of anxiety and depression is increased in cardiac patients as compared to the normal population. The risk of cardiovascular mortality is enhanced in patients suffering from depression. Comorbid anxiety disorders worsen the course of cardiac arrhythmias. Disturbance of neurocardiac regulation with predominance of the sympathetic tone is hypothesized to be causative for this. The emotional reaction to cardiac arrhythmias is differing to a large extent between individuals. Emotional stress may result from coping with treatment of cardiac arrhythmias. Emotional stress and cardiac arrhythmias may influence each other in the sense of a vicious circle. Somatoform cardiac arrhythmias are predominantly of psychogenic origin. Instrumental measures and frequent contacts between physicians and patients may facilitate disease chronification. The present review is dealing with the multifaceted relationships between cardiac arrhythmias and emotional stress. The underlying mechanisms and corresponding treatment modalities are discussed.

Development and initial psychometric evaluation of the Patient Perspective of Arrhythmia Questionnaire

There are no disease-specific questionnaires to measure patient sensitive outcomes in arrhythmia patients. We report the development and preliminary psychometric testing of the Patient Perception of Arrhythmia Questionnaire (PPAQ). The PPAQ was developed using formative research, exploratory factor analysis, expert review, pilot study, and regression. The PPAQ measures frequency and duration of episodes, symptoms, impact on daily activities, and restricted activity days. After preliminary content validation, the sensitivity of the PPAQ was tested in 103 arrhythmia patients. The measures showed good sensitivity and reliability. Preliminary construct validation was supported by significant differences (p < .001) among groups of arrhythmia patients consistent with clinical patterns. Preliminary evidence from patients with supraventricular arrhythmias suggests that the questionnaire has acceptable psychometrics and could be useful in future studies of arrhythmia patients.