A beating heart cell model to predict cardiotoxicity: effects of the dietary supplement ingredients higenamine, phenylethylamine, ephedrine and caffeine

Some dietary supplements may contain cardiac stimulants and potential cardiotoxins. In vitro studies may identify ingredients of concern. A beating human cardiomyocyte cell line was used to evaluate cellular effects following phenylethylamine (PEA), higenamine, ephedrine or caffeine treatment. PEA and higenamine exposure levels simulated published blood levels in humans or animals after intravenous administration. Ephedrine and caffeine levels approximated published blood levels following human oral intake. At low or midrange levels, each chemical was examined plus or minus 50 µM caffeine, simulating human blood levels reported after consumption of caffeine-enriched dietary supplements. To measure beats per minute (BPM), peak width, etc., rhythmic rise and fall in intracellular calcium levels following 30 min of treatment was examined. Higenamine 31.3 ng/ml or 313 ng/ml significantly increased BPM in an escalating manner. PEA increased BPM at 0.8 and 8 µg/ml, while 80 µg/ml PEA reduced BPM and widened peaks. Ephedrine produced a significant BPM dose response from 0.5 to 5.0 µM. Caffeine increased BPM only at a toxic level of 250 µM. Adding caffeine to PEA or higenamine but not ephedrine further increased BPM. These in vitro results suggest that additional testing may be warranted in vivo to further evaluate these effects.

Electrocardiographic assessments and cardiac events after fingolimod first dose - a comprehensive monitoring study

Background

First dose observation for cardiac effects is required for fingolimod, but recommendations on the extent vary. This study aims to assess cardiac safety of fingolimod first dose. Individual bradyarrhythmic episodes were evaluated to assess the relevance of continuous electrocardiogram (ECG) monitoring.

Methods

START is an ongoing open-label, multi-center study. At the time of analysis 3951 patients were enrolled. The primary endpoints are the incidence of bradycardia (heart rate < 45 bpm) and second-/third-degree AV blocks during treatment initiation. The relevance of Holter was assessed by matching ECG findings with the occurrence of clinical symptoms as well as by rigorous analysis of AV blocks with regard to the duration of pauses and the minimal heart rate recorded during AV block.

Results

Thirty-one patients (0.8%) developed bradycardia (<45 bpm), 62 patients (1.6%) had second-degree Mobitz I and/or 2:1 AV blocks with a lowest reading (i.e. mean of ten consecutive beats) of 35 bpm and the longest pause lasting for 2.6 s. No Mobitz II or third-degree AV blocks were observed. Only one patient complained about mild chest discomfort and fatigue. After 1 week, there was no second-/third-degree AV block.

Conclusions

Continuous Holter ECG monitoring in this large real-life cohort revealed that bradycardia and AV conduction abnormalities were rare, transient and benign. No further unexpected abnormalities were detected. The data presented here give an indication that continuous Holter ECG monitoring does not add clinically relevant value to patients’ safety.

Trial registration

NCT01585298; registered April 23, 2012.

Ecstasy (3,4-methylenedioxymethamphetamine): Cardiovascular effects and mechanisms

3,4-methylenedioxymethamphetamine or MDMA (known as "ecstasy") is a recreational drug of abuse, popular worldwide for its distinctive psychotropic effects. Currently, the therapeutic potential of MDMA in psychotherapy has attracted a lot of interest from the scientific community, despite the multitude of effects that this drug of abuse elicits on the human body. While neuronal effects have been the most studied, cardiovascular effects have also been described, as increased blood pressure and heart rate are the most recognizable. However, other effects have also been described at the cardiac (impaired cardiac contractile function, arrhythmias, myocardial necrosis and valvular heart disease) and vascular (vasoconstriction, disruption of vascular integrity and altered haemostasis) levels. Several mechanisms have been proposed, from the interaction with monoamine transporters and receptors to the promotion of oxidative stress or the activation of matrix metalloproteinases (MMPs). This review provides an overview of the cardiovascular implications of MDMA intake and underlying mechanisms, relevant when considering its consumption as drug of abuse but also when considering its therapeutic potential in psychiatry. Moreover, the risk/benefit ratio of the therapeutic use of MDMA remains to be fully elucidated from a cardiovascular standpoint, particularly in patients with underlying cardiovascular disease.

Cardiovascular responses to sugary drinks in humans: galactose presents milder cardiac effects than glucose or fructose

PURPOSE

There is increasing interest into the potentially beneficial effects of galactose for obesity and type 2 diabetes management as it is a low-glycemic sugar reported to increase satiety and fat mobilization. However, fructose is also a low-glycemic sugar but with greater blood pressure elevation effects than after glucose ingestion. Therefore, we investigated here the extent to which the ingestion of galactose, compared to glucose and fructose, impacts upon haemodynamics and blood pressure.

METHODS

In a randomized cross-over study design, 9 overnight-fasted young men attended 3 separate morning sessions during which continuous cardiovascular monitoring was performed at rest for at least 30 min before and 120 min after ingestion of 500 mL of water containing 60 g of either glucose, fructose or galactose. These measurements included beat-to-beat systolic and diastolic blood pressure, heart rate deduced by electrocardiography, and stroke volume derived by impedance cardiography; these measurements were used to calculate cardiac output and total peripheral resistance.

RESULTS

Ingestion of galactose, like glucose, led to significantly lesser increases in systolic, diastolic and mean blood pressure than fructose ingestion (p < 0.05). Furthermore, the increase in cardiac output and reduction in total peripheral resistance observed after ingestion of glucose were markedly lower after galactose ingestion (p < 0.01).

CONCLUSIONS

Galactose thus presents the interesting characteristics of a low-glycemic sugar with mild cardiovascular effects. Further studies are warranted to confirm the clinical relevance of the milder cardiovascular effects of galactose than other sugars for insulin resistant obese and/or diabetic patients with cardiac insufficiency.

Cardiovascular effects of severe late-onset preeclampsia are reversed within six months postpartum

OBJECTIVES

Preeclampsia (PE) is a common pregnancy-related disorder associated with cardiovascular long-term disease. Eighty percent are late-onset PE, occurring after 34 gestational weeks, and can present with severe symptoms. Magnitude and reversibility rate of maternal cardiovascular changes after severe late-onset PE have not been characterized. This study therefore evaluated longitudinal dynamics of maternal cardiovascular changes after severe late-onset PE.

STUDY DESIGN

Six previously normotensive women with severe late-onset PE and eight pregnant controls were included. Severe PE was defined as systolic blood pressure (SBP) ≥ 160 mmHg or diastolic blood pressure (DBP) ≥ 110 mmHg and proteinuria with/without evidence of end-organ dysfunction, or SBP ≥ 140 mmHg or DBP ≥ 90 mmHg with/without proteinuria and with evidence of end-organ dysfunction. Cardiovascular function was assessed by magnetic resonance imaging at 1-3 days, one week and six months postpartum.

RESULTS

Left ventricular mass at 1-3 days postpartum was higher after severe late-onset PE (57 g/m²) compared to after normal pregnancy (48 g/m²; p = 0.01). Pulse wave velocity (PWV) decreased between 1 and 3 days and six months postpartum after PE (6.1 to 5.0 m/s; p = 0.028). There was no difference in PWV 1-3 days postpartum after severe PE compared after normal pregnancy (6.1 versus 5.6 m/s; p = 0.175). Blood pressure normalized within six months in all but one patient.

CONCLUSIONS

Cardiac effects after severe late-onset PE were small and transient. This indicates that left ventricular hypertrophy after severe late-onset PE may be a secondary physiologic response to increased peripheral resistance in PE. Vascular mechanisms rather than persistent cardiac hypertrophy postpartum may be the culprit for increased long-term cardiovascular risk after PE.

E-cigarettes and arrhythmogenesis: a comprehensive review of pre-clinical studies and their clinical implications

Electronic cigarette use has grown exponentially in recent years, and while their popularity has increased, the long-term effects on the heart are yet to be fully studied and understood. Originally designed as devices to assist with those trying to quit traditional combustible cigarette use, their popularity has attracted use by teens and adolescents who traditionally have not smoked combustible cigarettes. Acute effects on the heart have been shown to be similar to traditional combustible cigarettes, including increased heart rate and blood pressure. The main components of electronic cigarettes that contribute to these arrhythmic effects are found in the e-liquid that is aerosolized and inhaled, comprised of nicotine, flavourings, and a combination of vegetable glycerin (VG) and propylene glycol (PG). Nicotine can potentially induce both ventricular and atrial arrhythmogenesis, with both the atrial and ventricular effects resulting from the interactions of nicotine and the catecholamines they release via potassium channels. Atrial arrhythmogenesis, more specifically atrial fibrillation, can also occur due to structural alterations, which happens because of nicotine downregulating microRNAs 133 and 590, both post-transcriptional growth factor repressors. Liquid flavourings and the combination of PG and VG can possibly lead to arrhythmic events by exposing users to acrolein, an aldehyde that stimulates TRPA1 that in turn causes a change towards sympathetic activation and autonomic imbalance. The design of these electronic delivery devices is constantly changing; therefore, it has proven extremely difficult to study the long-term effects on the heart caused by electronic cigarettes but will be important to understand given their rising popularity. The arrhythmic effects of electronic cigarettes appear similar to traditional cigarettes as well; however, a comprehensive review has not been compiled and is the focus of this article.

A functional selective effect of oxytocin secreted under restraint stress in rats

Restraint stress (RS) is an unavoidable stress model that triggers activation of the autonomic nervous system, endocrine activity, and behavioral changes in rodents. Furthermore, RS induces secretion of oxytocin into the bloodstream, indicating a possible physiological role in the stress response in this model. The presence of oxytocin receptors in vessels and heart favors this possible idea. However, the role of oxytocin secreted in RS and effects on the cardiovascular system are still unclear. The aim of this study was to analyze the influence of oxytocin on cardiovascular effects during RS sessions. Rats were subjected to pharmacological (blockade of either oxytocin, vasopressin, or muscarinic receptors) or surgical (hypophysectomy or sinoaortic denervation) approaches to study the functional role of oxytocin and its receptor during RS. Plasma levels of oxytocin and vasopressin were measured after RS. RS increased arterial pressure, heart rate, and plasma oxytocin content, but not vasopressin. Treatment with atosiban (a Gi biased agonist) inhibited restraint-evoked tachycardia without affecting blood pressure. However, this effect was no longer observed after sinoaortic denervation, homatropine (M2 muscarinic antagonist) treatment or hypophysectomy, indicating that parasympathetic activation mediated by oxytocin secreted to the periphery is responsible for blocking the increase in tachycardic responses observed in the atosiban-treated group. Corroborating this, L-368,899 (oxytocin antagonist) treatment showed an opposite effect to atosiban, increasing tachycardic responses to restraint. Thus, this provides evidence that oxytocin secreted to the periphery attenuates tachycardic responses evoked by restraint via increased parasympathetic activity, promoting cardioprotection by reducing the stress-evoked heart rate increase.

Effects of D-allose on ATP production and cell viability in neonatal rat cardiomyocytes

2-Deoxy-d-glucose (2DG) induces anticancer effects through glycolytic inhibition but it may raise the risk of arrhythmia. The rare monosaccharide d-allose also has anticancer properties, but its cardiac effects are unknown. We examined the effects of d-allose on adenosine triphosphate (ATP) production in neonatal rat cardiomyocytes. We showed that 25 mM d-allose selectively reduced glycolytic ATP, but had minimal impact on mitochondrial ATP, while 1 mM 2DG strongly inhibited both. Furthermore, d-allose had less impact on cell viability and was less cytotoxic than 2DG; neither compound caused apoptosis. Thus, d-allose selectively diminished glycolytic ATP production with no apparent effects on cardiomyocytes.

Effects Of Interferon Therapy On Heart

BACKGROUND

Hepatitis C virus (HCV) infection is a major health problem worldwide. Around 185 million people are suffering from HCV infection all over the world, out of which 10 million people are residing in Pakistan. 4.7% (2-14% by different studies) of Pakistanis are suffering from this deadly disease. Interferon+Ribavarin IFN/RIB is the mainstay of treatment for this infection. Various cardiovascular adverse reactions have been reported of this therapy. We conducted this study at Punjab Institute of cardiology to look for the cardiac safety of interferon therapy in our population.

METHODS

We studied HCV infected patients planned for interferon therapy between 21st of November 2012 to 20th of August 2014. Echocardiography was performed before, during and after the completion of therapy. Pegylated interferon once a week plus ribavirin therapy was given to the patients. Patients received 16-40 injections of pegylated interferon depending upon the decision of hepatologist. Patients with prior structural heart disease, patients who did not start the treatment or patients who did not turn up on follow up were excluded from the study.

RESULTS

A total of 102 patients planned to have interferon therapy were screened echocardiographically. One patient died after 5 injections due to infection (a non-cardiac cause). 46 patients completed the treatment and the follow up. None of the patients had any acute cardiac event. All patients had normal biventricular systolic function at the end of study. None of the patients had significant valvular heart disease or pulmonary hypertension. Reversal of E/A ratio or E/A ratio>2, parameters of diastolic dysfunction and mild pericardial effusion were noted in a statistically significant number of patients.

CONCLUSIONS

Interferon therapy for HCV infection is cardiac safe in patients who have structurally normal heart. Female patients have propensity of adverse events like severe diastolic dysfunction and mild pericardial effusion. The safety of drug in patients already having cardiac ailment needs to be studied. Moreover HCV infection itself is not injurious to the heart.

Evaluation of the Renal and Cardiovascular Effects of Long-Term Tolvaptan Treatment in Autosomal Dominant Polycystic Kidney Disease

INTRODUCTION

Cardiovascular diseases constitute a significant cause of morbidity and mortality in individuals with autosomal dominant polycystic kidney disease (ADPKD). This study aimed to assess the long-term effects of tolvaptan on the kidneys and heart in rapidly progressing ADPKD.

METHODS

Among 354 patients diagnosed with ADPKD, 58 meeting the eligibility criteria for tolvaptan were included in the study. The study comprised two groups with similar demographic and clinical characteristics: 29 patients receiving tolvaptan treatment and 29 in the control group. Several included genetic analysis, magnetic resonance imaging, and echocardiography. Clinical and cardiac changes were recorded in both groups after a 3-year follow-up.

RESULTS

Tolvaptan treatment demonstrated a significant reduction in the rate of eGFR decline compared to the control group. Furthermore, it was observed that tolvaptan could prevent the development of cardiac arrhythmias by inhibiting an increase in QTc interval and heart rate.

CONCLUSION

These findings suggest that, in addition to slowing kidney progression in ADPKD management, tolvaptan may potentially benefit in preventing cardiac complications.