The arrhythmogenicity of theophylline. A multivariate analysis of clinical determinants

Preliminary Evidence of the Potent and Selective Adenosine A2B Receptor Antagonist PSB-603 in Reducing Obesity and Some of Its Associated Metabolic Disorders in Mice

The adenosine A2A and A2B receptors are promising therapeutic targets in the treatment of obesity and diabetes since the agonists and antagonists of these receptors have the potential to positively affect metabolic disorders. The present study investigated the link between body weight reduction, glucose homeostasis, and anti-inflammatory activity induced by a highly potent and specific adenosine A2B receptor antagonist, compound PSB-603. Mice were fed a high-fat diet for 14 weeks, and after 12 weeks, they were treated for 14 days intraperitoneally with the test compound. The A1/A2A/A2B receptor antagonist theophylline was used as a reference. Following two weeks of treatment, different biochemical parameters were determined, including total cholesterol, triglycerides, glucose, TNF-α, and IL-6 blood levels, as well as glucose and insulin tolerance. To avoid false positive results, mouse locomotor and spontaneous activities were assessed. Both theophylline and PSB-603 significantly reduced body weight in obese mice. Both compounds had no effects on glucose levels in the obese state; however, PSB-603, contrary to theophylline, significantly reduced triglycerides and total cholesterol blood levels. Thus, our observations showed that selective A2B adenosine receptor blockade has a more favourable effect on the lipid profile than nonselective inhibition.

Optimal Management of Heart Failure and Chronic Obstructive Pulmonary Disease: Clinical Challenges

Heart failure (HF) and chronic obstructive pulmonary disease (COPD) are common causes of breathlessness which frequently co-exist; one potentially exacerbating the other. Distinguishing between the two can be challenging due to their similar symptomatology and overlapping risk factors, but a timely and correct diagnosis is potentially lifesaving. Modern treatment for HF can substantially improve symptoms and prognosis for many patients and may have beneficial effects for patients with COPD. Conversely, while many inhaled treatments for COPD can improve symptoms and reduce exacerbations, there is conflicting evidence regarding the safety of some inhaled treatments for COPD in patients with HF. Here we explore the overlap between HF and COPD, examine the effect of one condition on the other, and address the challenges of managing patients with both conditions.

Aminophylline Induces Two Types of Arrhythmic Events in Human Pluripotent Stem Cell-Derived Cardiomyocytes

Cardiac side effects of some pulmonary drugs are observed in clinical practice. Aminophylline, a methylxanthine bronchodilator with documented proarrhythmic action, may serve as an example. Data on the action of aminophylline on cardiac cell electrophysiology and contractility are not available. Hence, this study was focused on the analysis of changes in the beat rate and contraction force of human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) and HL-1 cardiomyocytes in the presence of increasing concentrations of aminophylline (10 µM-10 mM in hPSC-CM and 8-512 µM in HL-1 cardiomyocytes). Basic biomedical parameters, namely, the beat rate (BR) and contraction force, were assessed in hPSC-CMs using an atomic force microscope (AFM). The beat rate changes under aminophylline were also examined on the HL-1 cardiac muscle cell line via a multielectrode array (MEA). Additionally, calcium imaging was used to evaluate the effect of aminophylline on intracellular Ca2+ dynamics in HL-1 cardiomyocytes. The BR was significantly increased after the application of aminophylline both in hPSC-CMs (with 10 mM aminophylline) and in HL-1 cardiomyocytes (with 256 and 512 µM aminophylline) in comparison with controls. A significant increase in the contraction force was also observed in hPSC-CMs with 10 µM aminophylline (a similar trend was visible at higher concentrations as well). We demonstrated that all aminophylline concentrations significantly increased the frequency of rhythm irregularities (extreme interbeat intervals) both in hPSC-CMs and HL-1 cells. The occurrence of the calcium sparks in HL-1 cardiomyocytes was significantly increased with the presence of 512 µM aminophylline. We conclude that the observed aberrant cardiomyocyte response to aminophylline suggests an arrhythmogenic potential of the drug. The acquired data represent a missing link between the arrhythmic events related to the aminophylline/theophylline treatment in clinical practice and describe cellular mechanisms of methylxanthine arrhythmogenesis. An AFM combined with hPSC-CMs may serve as a robust platform for direct drug effect screening.

Positionspapier „Schlafmedizin in der Kardiologie“, Update 2021

Es hat sich viel getan in der Welt der Schlafmedizin in der Kardiologie, weshalb eine vollwertige Überarbeitung des Positionspapiers „Schlafmedizin in der Kardiologie“ erforderlich wurde. In der aktuellen neuartigen Version finden sich nicht nur alle verfügbaren Studien, Literaturstellen und Updates zu Pathophysiologie, Diagnostik- und Therapieempfehlungen, sondern auch Ausblicke auf neue Entwicklungen und zukünftige Forschungserkenntnisse. Dieses überarbeitete Positionspapier gibt Empfehlungen für Diagnostik und Therapie von Patienten mit kardiovaskulären Erkrankungen mit schlafassoziierten Atmungsstörungen und erteilt darüber hinaus einen fundierten Überblick über verfügbare Therapien und Evidenzen, gibt aber ebenso Ratschläge wie mit Komorbiditäten umzugehen ist. Insbesondere enthält dieses überarbeitete Positionspapier aktualisierte Stellungnahmen zu schlafassoziierten Atmungsstörungen bei Patienten mit koronarer Herzerkrankung, Herzinsuffizienz, arterieller Hypertonie, aber auch für Patienten mit Vorhofflimmern. Darüber hinaus finden sich erstmals Empfehlungen zur Telemedizin als eigenes, neues Kapitel. Dieses Positionspapier bietet Kardiologen sowie Ärzten in der Behandlung von kardiovaskulären Patienten die Möglichkeit einer evidenzbasierten Behandlung der wachsend bedeutsamen und mit zunehmender Aufmerksamkeit behafteten Komorbidität schlafassoziierter Atmungsstörungen. Und nicht zuletzt besteht mit diesem neuen Positionspapier eine enge Verknüpfung mit dem neuen Curriculum Schlafmedizin der Deutschen Gesellschaft für Kardiologie, weshalb dieses Positionspapier eine Orientierung für die erworbenen Fähigkeiten des Curriculums im Umgang von kardiovaskulären Patienten mit schlafassoziierten Atmungsstörungen darstellt.

Drug-Induced Arrhythmias: A Scientific Statement From the American Heart Association

Many widely used medications may cause or exacerbate a variety of arrhythmias. Numerous antiarrhythmic agents, antimicrobial drugs, psychotropic medications, and methadone, as well as a growing list of drugs from other therapeutic classes (neurological drugs, anticancer agents, and many others), can prolong the QT interval and provoke torsades de pointes. Perhaps less familiar to clinicians is the fact that drugs can also trigger other arrhythmias, including bradyarrhythmias, atrial fibrillation/atrial flutter, atrial tachycardia, atrioventricular nodal reentrant tachycardia, monomorphic ventricular tachycardia, and Brugada syndrome. Some drug-induced arrhythmias (bradyarrhythmias, atrial tachycardia, atrioventricular node reentrant tachycardia) are significant predominantly because of their symptoms; others (monomorphic ventricular tachycardia, Brugada syndrome, torsades de pointes) may result in serious consequences, including sudden cardiac death. Mechanisms of arrhythmias are well known for some medications but, in other instances, remain poorly understood. For some drug-induced arrhythmias, particularly torsades de pointes, risk factors are well defined. Modification of risk factors, when possible, is important for prevention and risk reduction. In patients with nonmodifiable risk factors who require a potentially arrhythmia-inducing drug, enhanced electrocardiographic and other monitoring strategies may be beneficial for early detection and treatment. Management of drug-induced arrhythmias includes discontinuation of the offending medication and following treatment guidelines for the specific arrhythmia. In overdose situations, targeted detoxification strategies may be needed. Awareness of drugs that may cause arrhythmias and knowledge of distinct arrhythmias that may be drug-induced are essential for clinicians. Consideration of the possibility that a patient's arrythmia could be drug-induced is important.

Atropine-induced sinus tachycardia protects against exercise-induced ventricular arrhythmias in patients with catecholaminergic polymorphic ventricular tachycardia

AIMS

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited arrhythmia syndrome characterized by exercise-induced ventricular arrhythmias, sudden death, and sinus bradycardia. Elevating supraventricular rates with pacing or atropine protects against catecholaminergic ventricular arrhythmias in a CPVT mouse model. We tested the hypothesis that increasing sinus heart rate (HR) with atropine prevents exercise-induced ventricular arrhythmias in CPVT patients.

METHODS AND RESULTS

We performed a prospective open-label trial of atropine prior to exercise in CPVT patients (clinicaltrials.gov NCT02927223). Subjects performed a baseline standard Bruce treadmill test on their usual medical regimen. After a 2-h recovery period, subjects performed a second exercise test after parasympathetic block with atropine (0.04 mg/kg intravenous). The primary outcome measure was the total number of ventricular ectopic beats during exercise. All six subjects (5 men, 22-57 years old) completed the study with no adverse events. Atropine increased resting sinus rate from median 52 b.p.m. (range 52-64) to 98 b.p.m. (84-119), P = 0.02. Peak HRs (149 b.p.m., range 136-181 vs. 149 b.p.m., range 127-182, P = 0.46) and exercise duration (612 s, range 544-733 vs. 584 s, range 543-742, P = 0.22) were not statistically different. All subjects had ventricular ectopy during the baseline exercise test. Atropine pre-treatment significantly decreased the median number of ventricular ectopic beats from 46 (6-192) to 0 (0-29), P = 0.026; ventricular ectopy was completely eliminated in 4/6 subjects.

CONCLUSION

Elevating sinus rates with atropine reduces or eliminates exercise-induced ventricular ectopy in patients with CPVT. Increasing supraventricular rates may represent a novel therapeutic strategy in CPVT.

Bronchodilators in subjects with asthma-related comorbidities

Asthma is often associated with different comorbidities such as cardiovascular diseases, depression, diabetes mellitus, dyslipidaemia, osteoporosis, rhinosinusitis and mainly gastro-oesophageal reflux disease and allergic rhinitis. Although bronchodilators play an important role in the treatment of asthma, there is no overall description of their impact on comorbid asthma, regardless of whether favourable or negative. This narrative review examines the potential effects of bronchodilators on comorbidities of asthma.

Non-Mask-based Therapies for Central Sleep Apnea in Patients with Heart Failure

Central sleep apnea is common in heart failure and contributes to morbidity and mortality. Symptoms are often similar to those associated with heart failure and a high index of suspicion is needed. Testing is typically done in the sleep laboratory, but home testing equipment can distinguish between central and obstructive events. Treatments are limited. Mask-based therapies have been the primary treatment. Oxygen has some data but lacks long-term studies. Neurostimulation of the phrenic nerve is a new technology that has demonstrated improvement. Coordination of care between sleep specialists and cardiologists is important as the field of central sleep apnea continues to develop.

Cafedrine/Theodrenaline (20:1) Is an Established Alternative for the Management of Arterial Hypotension in Germany-a Review Based on a Systematic Literature Search

A 20:1 combination of cafedrine:theodrenaline (Akrinor®) is widely used in Germany for the treatment of hypotensive states during anesthesia and in emergency medicine. Although this drug formulation has been available since 1963, there are few studies relating to its use and many of the data are only available in German. In this article, we summarize the available data and propose mechanisms for the effects of cafedrine/theodrenaline on cardiac muscle cells and vascular smooth muscle cells. Cafedrine/theodrenaline leads to a rapid increase in mean arterial pressure that is characterized by increased cardiac preload, stroke volume, and cardiac output. Systemic vascular resistance and heart rate remain mostly unchanged. Factors which impact the effects of cafedrine/theodrenaline are gender, high arterial pressure at baseline, use of β-blockers, and heart failure. Importantly, the drug is frequently used in obstetric anesthesia without detrimental effects on umbilical cord pH or APGAR score.

Cardiac Arrhythmias in Patients with Exacerbation of COPD

Supraventricular and ventricular arrhythmias are common among patients with chronic obstructive pulmonary disease (COPD). Multiple factors can contribute to the development of arrhythmias in patients with exacerbation of the disease, including: respiratory or heart failure, hypertension, coronary disease and also medications. In the present study we seek to determine the prevalence of cardiac arrhythmias and risk factors among patients with exacerbation of COPD. The study was a retrospective evaluation of 2753 24-h Holter recordings of patients hospitalized in 2004-2016. Exacerbation of COPD was diagnosed in 152 patients and the prevalence of arrhythmias in this group of patients was 97%. The commonest arrhythmia was ventricular premature beats (VPB) - 88.8%, followed by supraventricular premature beats (SPB) - 56.5%. Permanent atrial fibrillation accounted for 30.3% and paroxysmal atrial fibrillation (PAF) for 12.5%. Supraventricular tachycardia (SVT) was noted in 34.2% patients and ventricular tachycardia in 25.6%. Respiratory failure increased the risk of SPB, while heart failure increased the risk of VPB. Treatment with theophylline was associated with a higher proportion of PAF and SVT. In conclusion, COPD exacerbation is associated with a high prevalence of cardiac arrhythmias. COPD treatment and comorbidities increase the risk of arrhythmias.

The effect of ivabradine on functional capacity in patients with chronic obstructive pulmonary disease

Increased sympathetic tone and use of bronchodilators increase heart rate and this may worsen functional capacity in patients with chronic obstructive pulmonary disease (COPD). The aim of this study was to look at the short-term effect of the heart rate lowering drug ivabradine on clinical status in COPD patients.We randomised 80 COPD patients with sinus heart rate ≥90 bpm into either taking ivabradine 7.5 mg twice per day or placebo for two weeks. We assessed all patients using the modified Borg scale and 6-minute walk test at baseline and then again 2 weeks after randomisation.There were no significant differences in age, sex, severity of airway obstruction (measured using forceful exhalation), severity of diastolic dysfunction or pulmonary artery systolic pressure between the two groups. The ivabradine group showed significant improvement in 6-minute walk distance (from 192.6±108.8 m at baseline to 285.1±88.9 m at the end of the study) compared with the control group (230.6±68.4 at baseline and 250.4±65.8 m at the end of study) (p<0.001). This improvement in the drug group was associated with significant improvement of dyspnea on modified Borg scale (p=0.007).Lowering heart rate with ivabradine can improve exercise capacity and functional class in COPD patients with resting heart rate >90 bpm.

Increased risk of atrial fibrillation in end-stage renal disease patients on dialysis: A nationwide, population-based study in Taiwan

End-stage renal disease (ESRD) patients commonly have a higher risk of developing cardiovascular diseases than general population. Chronic kidney disease is an independent risk factor for atrial fibrillation (AF); however, little is known about the AF risk among ESRD patients with various modalities of renal replacement therapy. We used the Taiwan National Health Insurance Research Database to determine the incident AF among peritoneal dialysis (PD) and hemodialysis (HD) patients in Taiwan.Our ESRD cohort include Taiwan National Health Insurance Research Database, we identified 15,947 patients, who started renal replacement therapy between January 1, 2002 and December 31, 2003. From the same data source, 47,841 controls without ESRD (3 subjects for each patient) were identified randomly and frequency matched by gender, age (±1 year), and the year of the study patient's index date for ESRD between January 1, 2002 and December 31, 2003.During the follow-up period (mean duration: 8-10 years), 3428 individuals developed the new-onset AF. The incidence rate ratios for AF were 2.07 (95% confidence interval [CI] = 1.93-2.23) and 1.78 (95% CI = 1.30-2.44) in HD and PD groups, respectively. After we adjusted for age, gender, and comorbidities, the hazard ratios for the AF risk were 1.46 (95% CI = 1.32-1.61) and 1.32 (95% CI = 1.00-1.83) in HD and PD groups, respectively. ESRD patients with a history of certain comorbidities including hypertension, diabetes mellitus, hyperlipidemia, coronary artery disease, heart failure, valvular heart disease, and chronic obstructive pulmonary disease (COPD) have significantly increased risks of AF.This nationwide, population-based study suggests that incidence of AF is increased among dialysis ESRD patients. Furthermore, we have to pay more attention in clinical practice and long-term care for those ESRD patients with a history of certain comorbidities.

Drug treatment of COPD

Anticholinergics (in particular, ipratropium bromide [Atrovent]) are first-line therapy in patients with chronic obstructive pulmonary disease (COPD). Although more studies are needed to support the use of combination therapy, adding an inhaled beta agonist to the therapeutic regimen is reasonable in patients who remain symptomatic and need quick relief. Patients frequently receive inadequate amounts of drug with standard doses delivered by metered-dose inhalers, often as the result of improper technique, so symptomatic patients may require higher doses. Caution is recommended when the dose of inhaled sympathomimetics is increased in COPD patients with ischemic heart disease or tachyarrhythmias. The addition of an oral sympathomimetic is seldom necessary. Theophylline may be considered in outpatients who remain symptomatic despite their use of inhaled bronchodilators, but heart disease, seizure disorders, and gastroesophageal reflux are contraindications. Corticosteroid therapy remains controversial but can be helpful in patients who still have severe disease despite maximum bronchodilator therapy. Antibiotics can be of benefit in COPD patients undergoing an exacerbation who have increasing dyspnea, cough, and phlegm production.

Cardiac effects of current treatments of chronic obstructive pulmonary disease

We review the cardiac safety of the drugs available at present for the maintenance treatment of chronic obstructive pulmonary disease (COPD) in stable disease, focusing on inhaled long-acting muscarinic antagonists (LAMA) and long-acting β2 agonists (LABA), used either as a monotherapy or as a fixed-dose combination. We report the difficulties of, and pitfalls in, the investigation of the safety of drug treatments in COPD, which is hampered by the so-called COPD trial paradox: on the one hand, COPD is defined as a systemic disease and is frequently associated with comorbidities (especially cardiovascular comorbidities), which have an important effect on the prognosis of individual patients; on the other hand, patients with COPD and cardiovascular or other coexisting illnesses are often excluded from participation in randomised controlled clinical trials. In these trials, inhaled long-acting bronchodilators, both LAMA or LABA, or both, seem to be safe when used in the appropriate dose in adherent patients with COPD without uncontrolled cardiovascular disease or other notable comorbidities. However, the cardiac safety of LAMA and LABA is less evident when used inappropriately (eg, overdosing) or in patients with COPD and substantial cardiovascular disease, prolonged QTc interval, or polypharmacy. Potential warnings about rare cardiac events caused by COPD treatment from meta-analyses and observational studies need to be confirmed in high quality large randomised controlled trials. Finally, we briefly cover the cardiac safety issues of chronic oral drug treatments for COPD, encompassing theophylline, phosphodiesterase inhibitors, and macrolides.

Atrial and Ventricular Arrhythmia-Associated Factors in Stable Patients with Chronic Obstructive Pulmonary Disease

BACKGROUND

Supraventricular and ventricular premature complexes (SVPC and VPC, respectively) are associated with chronic obstructive pulmonary disease (COPD) and with increased mortality in COPD patients. However, there are few reports on the causes of arrhythmia in COPD patients.

OBJECTIVES

This study explores the associations between cardiopulmonary dysfunction and COPD by comparing patients with defined arrhythmias (>100 beats per 24 h) and those without, based on 24-hour electrocardiogram (ECG) recordings.

METHODS

Patients with arrhythmia underwent a 24-hour ECG and subsequent pulmonary function tests, computed tomography, ECG, 6-min walk test (6MWT), and BODE (body mass index, airflow obstruction, modified Medical Research Council Dyspnoea Scale, exercise capacity) index calculation.

RESULTS

Of 103 study patients (71 COPD patients and 32 at-risk patients), 36 had VPC, 45 had SVPC, 20 had both, and 42 had neither. The predicted post-bronchodilator forced expiratory volume in 1 s, the proportion of low-attenuation area on computed tomography, and BODE index values were significantly worse in the SVPC and VPC groups compared with the corresponding reference groups. Patients in the VPC group showed significantly increased right ventricular pressure and increased desaturation in the 6MWT compared with the reference group. In the multivariate analyses, bronchodilator use was a significant risk factor in the SVPC group, whereas in the VPC group, all parameters of the BODE index except for the dyspnoea score were identified as risk factors.

CONCLUSIONS

Increased SVPC might be caused by bronchodilator use, whereas increased VPC is likely related to the peculiar pathophysiology of COPD.

Compartmentation of cAMP signalling in cardiomyocytes in health and disease

3',5'-cyclic adenosine monophosphate (cAMP) is a ubiquitous second messenger critically involved in the regulation of heart function. It has been shown to act in discrete subcellular signalling compartments formed by differentially localized receptors, phosphodiesterases and protein kinases. Cardiac diseases such as hypertrophy or heart failure are associated with structural and functional remodelling of these microdomains which leads to changes in cAMP compartmentation. In this review, we will discuss recent key findings which provided new insights into cAMP compartmentation in cardiomyocytes with a particular focus on its alterations in heart disease.

Canadian Thoracic Society 2011 guideline update: diagnosis and treatment of sleep disordered breathing

The Canadian Thoracic Society (CTS) published an executive summary of guidelines for the diagnosis and treatment of sleep disordered breathing in 2006⁄2007. These guidelines were developed during several meetings by a group of experts with evidence grading based on committee consensus. These guidelines were well received and the majority of the recommendations remain unchanged. The CTS embarked on a more rigorous process for the 2011 guideline update, and addressed eight areas that were believed to be controversial or in which new data emerged. The CTS Sleep Disordered Breathing Committee posed specific questions for each area. The recommendations regarding maximum assessment wait times, portable monitoring, treatment of asymptomatic adult obstructive sleep apnea patients, treatment with conventional continuous positive airway pressure compared with automatic continuous positive airway pressure, and treatment of central sleep apnea syndrome in heart failure patients replace the recommendations in the 2006⁄2007 guidelines. The recommendations on bariatric surgery, complex sleep apnea and optimum positive airway pressure technologies are new topics, which were not covered in the 2006⁄2007 guidelines.

[Cardiovascular manifestations in patients with COPD]

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) is characterized mainly by airway obstruction due to chronic bronchitis and/or emphysema. In addition, COPD is frequently associated with other health problems with serious systemic manifestations. In particular, COPD patients are at increased risk of cardiovascular disease.

BACKGROUND

Current knowledge about cardiovascular disease in patients with COPD mainly concerns the high prevalence of cardiac arrhythmias in this population. Systemic hypertension, cardiovascular disease, heart failure and cerebro-vascular disease are also frequently encountered. This review discusses the cardiovascular manifestations associated with COPD, excluding right heart failure due to pulmonary hypertension.

VIEWPOINTS AND CONCLUSION

Non pulmonary health problems in patients with COPD, such as cardiovascular disease, are arousing increasing interest in the medical community. More studies are needed to increase our knowledge of cardiovascular disease in COPD and allow better medical management of patients.

Caffeine induces Ca2+ release by reducing the threshold for luminal Ca2+ activation of the ryanodine receptor

Caffeine has long been used as a pharmacological probe for studying RyR (ryanodine receptor)-mediated Ca(2+) release and cardiac arrhythmias. However, the precise mechanism by which caffeine activates RyRs is elusive. In the present study, we investigated the effects of caffeine on spontaneous Ca(2+) release and on the response of single RyR2 (cardiac RyR) channels to luminal or cytosolic Ca(2+). We found that HEK-293 cells (human embryonic kidney cells) expressing RyR2 displayed partial or 'quantal' Ca(2+) release in response to repetitive additions of submaximal concentrations of caffeine. This quantal Ca(2+) release was abolished by ryanodine. Monitoring of endoplasmic reticulum luminal Ca(2+) revealed that caffeine reduced the luminal Ca(2+) threshold at which spontaneous Ca(2+) release occurs. Interestingly, spontaneous Ca(2+) release in the form of Ca(2+) oscillations persisted in the presence of 10 mM caffeine, and was diminished by ryanodine, demonstrating that unlike ryanodine, caffeine, even at high concentrations, does not hold the channel open. At the single-channel level, caffeine markedly reduced the threshold for luminal Ca(2+) activation, but had little effect on the threshold for cytosolic Ca(2+) activation, indicating that the major action of caffeine is to reduce the luminal, but not the cytosolic, Ca(2+) activation threshold. Furthermore, as with caffeine, the clinically relevant, pro-arrhythmic methylxanthines aminophylline and theophylline potentiated luminal Ca(2+) activation of RyR2, and increased the propensity for spontaneous Ca(2+) release, mimicking the effects of disease-linked RyR2 mutations. Collectively, our results demonstrate that caffeine triggers Ca(2+) release by reducing the threshold for luminal Ca(2+) activation of RyR2, and suggest that disease-linked RyR2 mutations and RyR2-interacting pro-arrhythmic agents may share the same arrhythmogenic mechanism.

Central sleep apnea: Pathophysiology and treatment

Central sleep apnea (CSA) is characterized by a lack of drive to breathe during sleep, resulting in repetitive periods of insufficient ventilation and compromised gas exchange. These nighttime breathing disturbances can lead to important comorbidity and increased risk of adverse cardiovascular outcomes. There are several manifestations of CSA, including high altitude-induced periodic breathing, idiopathic CSA, narcotic-induced central apnea, obesity hypoventilation syndrome, and Cheyne-Stokes breathing. While unstable ventilatory control during sleep is the hallmark of CSA, the pathophysiology and the prevalence of the various forms of CSA vary greatly. This brief review summarizes the underlying physiology and modulating components influencing ventilatory control in CSA, describes the etiology of each of the various forms of CSA, and examines the key factors that may exacerbate apnea severity. The clinical implications of improved CSA pathophysiology knowledge and the potential for novel therapeutic treatment approaches are also discussed.

Absence of electrocardiographic findings and improved function with once-daily tiotropium in patients with chronic obstructive pulmonary disease

STUDY OBJECTIVES

To examine electrocardiographic findings after short- and long-term tiotropium therapy in patients with chronic obstructive pulmonary disease (COPD), and to establish previously reported symptomatic efficacy.

DESIGN

Randomized, double-blind, placebo-controlled, parallel-group study.

SETTING

Twelve outpatient investigational centers in the United States.

PATIENTS

One hundred ninety-six patients with COPD.

INTERVENTIONS

Patients received either tiotropium 18 mug once/day or placebo, delivered by the HandiHaler device.

MEASUREMENTS AND MAIN RESULTS

Electrocardiography (predose and 5 min postdose) and 24-hour Holter monitoring were performed at baseline and after 8 and 12 weeks of treatment with tiotropium 18 microg once/day or placebo. Efficacy measures (spirometry, global COPD ratings, scores on the EuroQol Health Questionnaire [EQ-5D], albuterol inhaler as needed) were included to demonstrate that the study population exhibited the characteristic improvements observed in previous tiotropium studies. Mean baseline forced expiratory volume in 1 second (FEV1) was 1.03 L. Mean changes in heart rate from baseline were similar in both groups. No differences were noted in the percentage of patients developing rhythm or conduction abnormalities detected with electrocardiography or Holter monitoring. Frequency of premature beats and mean maximal changes in PR, QRS, QT, QTcB, and QTcF intervals were similar in both groups. No patients developed new-onset QT or QTc intervals greater than 500 msec, and no differences were noted in the percentage of patients developing new QT prolongation less than 30 msec, 30-60 msec, or greater than 60 msec. At 12 weeks, predose and postdose improvements in FEV1 were 184 and 265 ml, respectively, with tiotropium versus placebo (p<0.001). Physician and patient global COPD ratings and the EQ-5D visual analog scale scores were improved with tiotropium (p<0.05); as-needed albuterol was reduced by 25% relative to placebo (p<0.05).

CONCLUSION

Tiotropium provided spirometric and symptomatic benefits in patients with COPD and was not associated with evidence of electrocardiographic changes in heart rate, rhythm, QT intervals, or conduction.

Treatment of sleep apnea in heart failure

Obstructive and central sleep apnea are common in heart failure, and may participate in its progression by exposing the heart to intermittent hypoxia, increased preload and afterload, sympathetic activation, and vascular endothelial dysfunction. Treatment of sleep apnea in patients with heart failure may reverse these detrimental effects, in addition to alleviating symptoms of sleep apnea. In patients with heart failure and obstructive sleep apnea, short-term randomized trials have demonstrated that continuous positive airway pressure (CPAP) improves cardiac function, and lowers sympathetic activity and blood pressure. However, there are no data on whether treating obstructive sleep apnea in patients with heart failure improves morbidity and mortality. Various treatments have been tested in heart failure patients with central sleep apnea, particularly oxygen and CPAP. Both reduce the frequency of central respiratory events, and lower sympathetic activity. In addition, CPAP improves cardiac function. However, the largest randomized trial did not demonstrate any beneficial effect of CPAP on the rate of mortality and cardiac transplantation (32 vs. 32 events in the control and treatment groups, respectively; p=0.54), but ultimately lacked power to conclude with certainty whether CPAP has an effect on morbidity and mortality in such patients. Thus, although there are data to indicate that treating both obstructive and central sleep apnea in patients with heart failure improves cardiovascular function, larger randomized trials involving interventions such as oxygen, CPAP, or other forms of positive airway pressure will be required to determine whether treating these sleep-related breathing disorders reduces clinically important outcomes such as morbidity and mortality.

Phosphodiesterase 4D deficiency in the ryanodine-receptor complex promotes heart failure and arrhythmias

Phosphodiesterases (PDEs) regulate the local concentration of 3',5' cyclic adenosine monophosphate (cAMP) within cells. cAMP activates the cAMP-dependent protein kinase (PKA). In patients, PDE inhibitors have been linked to heart failure and cardiac arrhythmias, although the mechanisms are not understood. We show that PDE4D gene inactivation in mice results in a progressive cardiomyopathy, accelerated heart failure after myocardial infarction, and cardiac arrhythmias. The phosphodiesterase 4D3 (PDE4D3) was found in the cardiac ryanodine receptor (RyR2)/calcium-release-channel complex (required for excitation-contraction [EC] coupling in heart muscle). PDE4D3 levels in the RyR2 complex were reduced in failing human hearts, contributing to PKA-hyperphosphorylated, "leaky" RyR2 channels that promote cardiac dysfunction and arrhythmias. Cardiac arrhythmias and dysfunction associated with PDE4 inhibition or deficiency were suppressed in mice harboring RyR2 that cannot be PKA phosphorylated. These data suggest that reduced PDE4D activity causes defective RyR2-channel function associated with heart failure and arrhythmias.

The use of bronchodilators in the treatment of airway obstruction in elderly patients

Ageing is associated with important anatomical, physiological and psychosocial changes that may have an impact on the management of obstructive airway diseases (asthma and chronic obstructive pulmonary disease (COPD)) and on their optimal therapy. Ageing-related modifications might be responsible for a different effectiveness of bronchodilators in the elderly patients as compared to younger subjects. Furthermore, the physiological involution of organs and the frequent comorbidity, often interfere with pharmacokinetics of bronchodilator drugs used in asthma and COPD. This review will focus on the use of bronchodilators in the elderly, with particular attention to the achievable goals and to rationale, utility and pitfalls in using the inhalation therapy in this age group. beta(2)-agonists, anticholinergics and methylxanthines will be discussed and their side effects in the elderly will be considered.

Respiratory medications and the risk of cardiac arrhythmias

BACKGROUND

Medications used to treat respiratory diseases include beta-adrenoceptors, antimuscarinics, inhaled and oral corticosteroids, and theophyllines. Most of these drugs have been associated indirectly with cardiac rhythm disorders, but epidemiologic evidence is limited.

METHODS

To evaluate the association between respiratory drugs and the occurrence of rhythm disorders among patients with asthma and those with chronic obstructive pulmonary disease, we conducted a case-control study nested in a population-based cohort of individuals 10-79 years of age and registered in the U.K. General Practice Research Database after 1 January 1994. The analysis included 710 confirmed cases and 5000 controls frequency-matched to cases by age (interval of 1 year) and sex.

RESULTS

No increased risk of arrhythmias overall was found among users of inhaled steroids (relative risk = 1.0; 95% confidence interval = 0.8-1.3). Short-term use of theophylline was weakly associated with arrhythmia (1.8; 1.0-3.3). An increased risk was found among users of oral steroids, and the relative risk was greater at the beginning of therapy (2.6; 2.0-3.5). The risk of atrial fibrillation was increased, especially for short-term use of oral steroids (2.7; 1.9-3.8), and a weak association was seen for theophyllines, especially short-term use (1.8; 0.9-3.7). Supraventricular tachycardia was associated with long-term use of oral steroids (2.1; 0.8-5.7), long-term use of antimuscarinics (1.7; 0.7-4.1), and short-term use of theophylline (4.0; 0.9-18.1). Ventricular arrhythmias were associated with oral steroids (3.2; 0.8-13.3) and beta-adrenoceptors (7.1; 0.8-65.9).

CONCLUSIONS

Oral steroids and theophylline were the therapeutic groups associated with risk of developing atrial fibrillation, especially with new courses of therapy. Results from this study also are consistent with certain suspected dysrhythmic effects of theophyllines, with supraventricular tachycardia associated with antimuscarinics, and with ventricular arrhythmias associated with beta-adrenoceptors.

Relationship between arterial blood gas values, pulmonary function tests and treadmill exercise testing parameters in patients with COPD

OBJECTIVE

There have been controversial reports regarding the relationship between exercise tolerance and resting pulmonary function in patients with COPD. The aim of this study was to examine the relationship between resting pulmonary function tests (rPFT) and cardiopulmonary exercise testing parameters (CETP) and their value in estimating exercise tolerance of patients.

METHODOLOGY

In total, 45 patients with COPD (nine females, 36 males; mean age 61.2 +/- 11.2) and 21 healthy subjects (four females, 17 males; mean age 60.3 +/- 9.7) as a control group were studied. COPD patients (group I) were divided into three subgroups according to their FEV(1) (mild/group II: FEV(1) 60-79% of predicted; moderate/group III: FEV(1) 40-59%; severe/group IV: FEV(1) < 40%). In controls FEV(1) was >/= 80%.

RESULTS

There were significant correlations between FEV(1) and CETP in group III (maximal O(2) consumption (mVO(2)), r= 0.35, P < 0.005; total treadmill time (TTT), r= 0.31, P < 0.01; total metabolic equivalent values (TMET), r= 0.29, P < 0.01)) and in group IV (mVO(2), r= 0.49, P < 0.001; TTT, r= 0.45, P < 0.005; TMET, r= 0.31, P < 0.01; peak heart rate (pHR), r= 0.29, P < 0.02; frequency of ventricular extrasystole (fVES), r=-0.27, P < 0.05). Additionally, in group IV there were significant correlations between PaO(2) and CETP (mVO(2), r= 0.41, P < 0.02; TTT, r= 0.38, P < 0.03; TMET, r= 0.31, P < 0.05; pHR, r= 0.29, P < 0.05; fVES, r=-0.28, P < 0.05).

CONCLUSION

There are significant correlations of resting FEV(1)% predicted and PaO(2) values with CETP in patients with moderate and severe COPD and these parameters may also have a role as indicators of exercise tolerance in these COPD patients.

PDE4 inhibitors in COPD—a more selective approach to treatment

Chronic obstructive pulmonary disease (COPD) is a serious and mounting global public health problem. Although its pathogenesis is incompletely understood, chronic inflammation plays an important part and so new therapies with a novel anti-inflammatory mechanism of action may be of benefit in the treatment of COPD. Cilomilast and roflumilast are potent and selective phosphodiesterase (PDE)4 inhibitors, with an improved therapeutic index compared with the weak, non-selective PDE inhibitor, theophylline. Unlike theophylline, which is limited by poor efficacy and an unfavourable safety and tolerability profile, the selective PDE4 inhibitors are generally well tolerated, with demonstrated efficacy in improving lung function, decreasing the rate of exacerbations and improving quality of life, with proven anti-inflammatory effects in patients with COPD. Theophylline is a difficult drug to use clinically, requiring careful titration and routine plasma monitoring due to the risk of toxic side effects, such as cardiovascular and central nervous system adverse events, with dose adjustments required in many patients, including smokers, the elderly and some patients on concomitant medications. In contrast, the selective PDE4 inhibitors are convenient medications for both patient and physician alike. Hence these agents represent a therapeutic advance in the treatment of COPD, due to their novel mechanism of action and potent anti-inflammatory effects, coupled with a good safety and tolerability profile.

Risk factors of emergency care and admissions in COPD patients with high consumption of health resources

This study is a case-control study looking to identify factors associated with frequent use of hospital services (emergency care and admissions) in COPD patients. Data from 64 patients with moderate-severe COPD (FEV1/FVC < or = 70, FEV1 < or = 50%) were prospectively collected, 32 cases with high consumption of health resources (COPD-HC) and 32 controls. COPD-HC was defined as a patient diagnosed of COPD requiring during one year: (1) two or more hospitalizations; (2) three or more emergency visits; or (3) one admission and two emergency visits. Patients with COPD and a similar age, FEV1 and PaO2 who required no hospital care during the study year (1998) were randomly selected as controls. Demographic, clinical and socioeconomic data were collected from each subject, and evaluations were made of anxiety, health-related quality of life [measured with the St. George's Respiratory Questionnaire (SGRQ)], nutritional parameters, and different therapeutic aspects. Forced spirometry, resting arterial blood gases, maximal respiratory muscle pressures and a 6-min walking test were measured in all cases. After applying a logistic regression model, the variables that finally proved to be independent predictors of frequent use of hospital services were: treatment with salmeterol, the presence of cardiac arrhythmias, and increased SGRQ scores. The administration of inhaled salmeterol multiplied the risk of having COPD-HC criteria by 27.4 (95%CI: 2.4-308.1), while the presence of arrhythmias multiplied the probability of meeting high consumption criteria by 24.3 (95%CI: 1.7-340.1). For each point of worsened quality of life, the risk of hospital care increased 1.06-fold (95%CI: 1.01-1.10). Although a severity bias related to the presence of long-acting beta2-agonists in the final regression equation cannot be ruled out, the variables associated in our sample to an increased utilization of hospital services are the regular use of inhaled salmeterol, the presence of cardiac arrhythmias, and an impaired health-related quality of life. The use of specific strategies aimed at modulating these aspects could, at least in theory, reduce the number of exacerbations requiring hospital care, with the resultant individual and collective benefits derived.

Sleep-Breathing Disorders and Heart Failure

Cheyne-Stokes respiration is known to be associated with severe left heart failure. Because of severe desaturation, sleep fragmentation, arousals, and an increase in sympathetic activity, Cheyne-Stokes respiration may lead to a further impairment of cardiac function and to a worsening of quality of life. Although the pathology of Cheyne-Stokes respiration is not fully understood, enhanced chemoreceptor sensitivity, prolonged circulation time, as well as decreased pulmonary gas stores and increased ventilatory drive may be contributing factors. Therapeutic options include the improvement of cardiac failure; medical treatment, such as using theophylline; continous positive airway pressure ventilation; and low-flow oxygen supply. Because of severe cardiac insufficiency, change of endothoracic pressure may worsen the hemodynamic situation in some patients. Therefore, this form of treatment has to be used carefully. Another possible treatment is a low-flow oxygen supply, which will prevent severe desaturations. This therapeutic approach might be a good alternative to noninvasive ventilation. However, it is controversial whether oxygen supply will improve quality of sleep of the patients, even in long-term treatment.

Fatal adverse drug events: the paradox of drug treatment

OBJECTIVE

Study patient characteristics, morbidity patterns and drug regimens associated with fatal adverse drug events (FADEs) amongst medical department inpatients.

DESIGN

An observational, descriptive study using aggregated medical records, autopsies and pre and postmortem drug analyses.

SETTING

A department of internal medicine at a Norwegian county hospital.

SUBJECTS

All patients dying in the department over a 2-year period.

RESULTS

The incidence of FADEs were 18.2% (133/732). Compared with non-FADE cases, FADE cases were older, used more drugs both on admission and at death, and had higher comorbidity (P < 0.001). Drugs suspected to cause or contribute to fatal outcome were mainly those used for treating chronic pulmonary diseases (terbutaline, theophylline), antithrombotic drugs (aspirin, warfarin, heparines) and drugs for treating coronary heart disease and heart failure (e.g. diuretics, nitrates, angiotensin converting enzymes (ACE) inhibitors, calcium channel blockers). Bronchodilatory drugs, antithrombotic drugs and cardiovascular drugs account for 26, 31 and 30 FADE cases, respectively. Patients dying from gastrointestinal diseases had the highest relative FADE occurrence (42%), cancer patients the lowest occurrence (4%). Serious drug-drug and drug-disease interactions were frequently suspected. Various degrees of inappropriateness in choice of drug, dosage or administration route were seen in 50% of FADE cases.

CONCLUSIONS

This study shows a high incidence of FADEs associated with high age, high comorbidity and polypharmacy, and partly to inappropriate drug prescribing or use. Treatments frequently associated with FADEs were bronchodilatory treatment of patients with both chronic obstructive lung disease and coronary heart disease, vasodilatory treatment in patient with endstage heart failure and the combination of several antithrombotic drugs. A systematic strategy is needed to avoid unnecessary adverse drug events (ADEs).

Nocturnal asthma uncontrolled by inhaled corticosteroids: theophylline or long-acting beta2 agonists?

Asthma is an inflammatory disease of the airways that is frequently characterised by marked circadian rhythm. Nocturnal and early morning symptoms are quite common among patients with asthma. Increased mortality and decreased quality of life are associated with nocturnal asthma. Although numerous mechanisms contribute to the pathophysiology of nocturnal asthma, increasing evidence suggests the most important mechanisms relate to airway inflammation. According to international guidelines, patients with persistent asthma should receive long term daily anti-inflammatory therapy. A therapeutic trial with anti-inflammatory therapy alone (without a long-acting bronchodilator) should be assessed to determine if this therapy will eliminate nocturnal and early morning symptoms. If environmental control and low to moderate doses of inhaled corticosteroids do not eliminate nocturnal symptoms, the addition of a long-acting bronchodilator is warranted. Long-acting inhaled beta2 agonists (e.g. salmeterol, formoterol) are effective in managing nocturnal asthma that is inadequately controlled by anti-inflammatory agents. In addition, sustained release theophylline and controlled release oral beta2 agonists are effective. In patients with nocturnal symptoms despite low to high doses of inhaled corticosteroids, the addition of salmeterol has been demonstrated to be superior to doubling the inhaled corticosteroid dose. In trials comparing salmeterol with theophylline, 3 studies revealed salmeterol was superior to theophylline (as measured by e.g. morning peak expiratory flow, percent decrease in awakenings, and need for rescue salbutamol), whereas 2 studies found the therapies of equal efficacy. Studies comparing salmeterol to oral long-acting beta2 agonists reveal salmeterol to be superior to terbutaline and equivalent in efficacy to other oral agents. Microarousals unrelated to asthma are consistently increased when theophylline is compared to salmeterol in laboratory sleep studies. In addition to efficacy data, clinicians must weigh benefits and risks in choosing therapy for nocturnal asthma. Long-acting inhaled beta2 agonists are generally well tolerated. If theophylline therapy is to be used safely, clinicians must be quite familiar with numerous factors that alter clearance of this drug, and they must be prepared to use appropriate doses and monitor serum concentrations. Comparative studies using validated, disease specific quality of life instruments (e.g. Asthma Quality of Life Questionnaire) have shown long-acting inhaled beta2 agonists are preferred to other long-acting bronchodilators. Examination of costs for these therapeutic options reveals that evening only doses of long-acting oral bronchodilators are less expensive than multiple inhaled doses. However, costs of monitoring serum concentrations, risks, quality of life and otheroutcome measures must also be considered. Long-acting inhaled beta2 agonists are the agents of choice for managing nocturnal asthma in patients who are symptomatic despite anti-inflammatory agents and other standard management (e.g. environmental control). These agents offer a high degree of efficacy along with a good margin of safety and improved quality of life.

Multifocal atrial tachycardia and Ibutilide

Multifocal atrial tachycardia is an electrocardiographic phenomenon seen primarily in the elderly. The hemodynamic consequences of multifocal atrial tachycardia in an elderly woman are presented. Successful treatment with Ibutilide is demonstrated. Treatment with a class III antiarrhythmic agent opposes the frequently accepted mechanism of triggered activity in causing this arrhythmia.

Sleep apnea in congestive heart failure

Sleep-related breathing disorders, including obstructive sleep apnea (OSA) and Cheyne-Stokes respiration with central sleep apnea (CSR-CSA), commonly occur in patients with congestive heart failure (CHF). In this setting they can have adverse pathophysiologic effects on the cardiovascular system. OSA may lead to development or progression of left ventricular (LV) dysfunction by increasing LV afterload through the combined effects of elevations in systemic blood pressure and a generation of exaggerated negative intrathoracic pressure, and by activating the sympathetic nervous system through the influence of hypoxia and arousals from sleep. Abolition of OSA by continuous positive airway pressure (CPAP) can improve cardiac function in patients with CHF. In contrast to OSA, CSR-CSA is likely a consequence rather than a cause of CHF. Here, pulmonary congestion causes hyperventilation by stimulating pulmonary irritant receptors. This leads to reductions in PaCO2 below the apneic threshold during sleep, precipitating posthyperventilatory central apneas. CSR-CSA is associated with increased mortality in CHF, probably because of sympathetic nervous system activation caused by recurrent apnea-induced hypoxia and arousals from sleep. Treatment of CSR-CSA by supplemental O2, theophylline, and CPAP can alleviate central apneas. Of these treatments, however, only CPAP has been shown to improve cardiac function and symptoms of heart failure. We conclude that effective treatments of OSA and CSR-CSA may prove to be useful adjuncts to the standard pharmacologic therapy of patients with CHF.

Effect of age on bronchodilator response in acute severe asthma treatment

STUDY OBJECTIVES

This study was designed to evaluate the effects of age on bronchodilator response to salbutamol in patients with acute severe asthma in the emergency department.

SUBJECTS AND METHODS

Sixty-four sequential patients (mean age, 34.2+/-10.7 years) with acute asthma were enrolled in the trial. Using age as a major criterion, we divided the sample in two groups: the young one (age < or = 35 years, n=30) and the older (> 35 years, n=34). All patients were treated with salbutamol delivered with metered-dose inhaler into a spacer device, in a dose of four puffs every 10 min (100 microg per actuation) during 3 h.

RESULTS

Mean FEV1 improved significantly over baseline values for both groups (p=0.001). At final disposition, the mean percent of predicted FEV1 was 55.1+/-16.3% in the young group and 58.0+/-20.9% in the older group. There were no significant differences between both groups for FEV1 percent response at any point studied. A significant increase in heart rate over baseline was seen in the older group (p=0.001). Older patients also presented a higher incidence in nausea and tremor. Young and older patients with acute asthma achieved equivalent bronchodilation response to salbutamol.

CONCLUSIONS

We concluded that age is not a predictor of response to beta-agonists.