Antiarrhythmic Sotalol, Occlusion/Occlusion-like Syndrome in Rats, and Stable Gastric Pentadecapeptide BPC 157 Therapy

We focused on the first demonstration that antiarrhythmics, particularly class II and class III antiarrhythmic and beta-blocker sotalol can induce severe occlusion/occlusion-like syndrome in rats. In this syndrome, as in similar syndromes with permanent occlusion of major vessels, peripheral and central, and other similar noxious procedures that severely disable endothelium function, the stable gastric pentadecapeptide BPC 157-collateral pathways activation, was a resolving therapy. After a high dose of sotalol (80 mg/kg intragastrically) in 180 min study, there were cause-consequence lesions in the brain (swelling, intracerebral hemorrhage), congestion in the heart, lung, liver, kidney, and gastrointestinal tract, severe bradycardia, and intracranial (superior sagittal sinus), portal and caval hypertension, and aortal hypotension, and widespread thrombosis, peripherally and centrally. Major vessels failed (congested inferior caval and superior mesenteric vein, collapsed azygos vein). BPC 157 therapy (10 µg, 10 ng/kg given intragastrically at 5 min or 90 min sotalol-time) effectively counteracted sotalol-occlusion/occlusion-like syndrome. In particular, eliminated were heart dilatation, and myocardial congestion affecting coronary veins and arteries, as well as myocardial vessels; eliminated were portal and caval hypertension, lung parenchyma congestion, venous and arterial thrombosis, attenuated aortal hypotension, and centrally, attenuated intracranial (superior sagittal sinus) hypertension, brain lesions and pronounced intracerebral hemorrhage. Further, BPC 157 eliminated and/or markedly attenuated liver, kidney, and gastrointestinal tract congestion and major veins congestion. Therefore, azygos vein activation and direct blood delivery were essential for particular BPC 157 effects. Thus, preventing such and similar events, and responding adequately when that event is at risk, strongly advocates for further BPC 157 therapy.

ArrhythmoGenoPharmacoTherapy

This review is focusing on the understanding of various factors and components governing and controlling the occurrence of ventricular arrhythmias including (i) the role of various ion channel-related changes in the action potential (AP), (ii) electrocardiograms (ECGs), (iii) some important arrhythmogenic mediators of reperfusion, and pharmacological approaches to their attenuation. The transmembrane potential in myocardial cells is depending on the cellular concentrations of several ions including sodium, calcium, and potassium on both sides of the cell membrane and active or inactive stages of ion channels. The movements of Na+, K+, and Ca2+ via cell membranes produce various currents that provoke AP, determining the cardiac cycle and heart function. A specific channel has its own type of gate, and it is opening and closing under specific transmembrane voltage, ionic, or metabolic conditions. APs of sinoatrial (SA) node, atrioventricular (AV) node, and Purkinje cells determine the pacemaker activity (depolarization phase 4) of the heart, leading to the surface manifestation, registration, and evaluation of ECG waves in both animal models and humans. AP and ECG changes are key factors in arrhythmogenesis, and the analysis of these changes serve for the clarification of the mechanisms of antiarrhythmic drugs. The classification of antiarrhythmic drugs may be based on their electrophysiological properties emphasizing the connection between basic electrophysiological activities and antiarrhythmic properties. The review also summarizes some important mechanisms of ventricular arrhythmias in the ischemic/reperfused myocardium and permits an assessment of antiarrhythmic potential of drugs used for pharmacotherapy under experimental and clinical conditions.

Ranolazine: Multifaceted Role beyond Coronary Artery Disease, a Recent Perspective

Ranolazine is a piperazine derivative approved as an antianginal. Primarily used as a second-line antianginal in stable coronary artery disease. Ranolazine blocks the late Na + current and prevents the rise of cytosolic calcium. It decreases myocardial wall tension and improves coronary blood flow. Ranolazine is effective in atrial fibrillation (AF) as an adjunct to electrical or pharmacological cardioversion. It can be used in combination with amiodarone or dronedarone. It has also been used in AF arising after coronary artery bypass grafting surgery. Role of ranolazine is also being evaluated in pulmonary arterial hypertension, diastolic dysfunction, and chemotherapy-induced cardiotoxicity. Ranolazine has some anti-glycemic effect and has shown a reduction of hemoglobin A1c in multiple trials. The antianginal effect of ranolazine has also been seen to be more in patients with diabetes compared to those without diabetes. Ranolazine is being evaluated in patients with the peripheral arterial disease with intermittent claudication and hypertrophic cardiomyopathy. Pilot studies have shown that ranolazine may be beneficial in neurological conditions with myotonia. The evidence-base on the use of ranolazine in various conditions is rapidly increasing with results of further trials eagerly awaited. Accumulating evidence may see ranolazine in routine clinical use for many conditions beyond its traditional role as an antianginal.

Editor's Choice- Reperfusion cardiac arrhythmias and their relation to reperfusion-induced cell death

Reperfusion does not only salvage ischaemic myocardium but can also cause additional cell death which is called lethal reperfusion injury. The time of reperfusion is often accompanied by ventricular arrhythmias, i.e. reperfusion arrhythmias. While both conditions are seen as separate processes, recent research has shown that reperfusion arrhythmias are related to larger infarct size. The pathophysiology of fatal reperfusion injury revolves around intracellular calcium overload and reactive oxidative species inducing apoptosis by opening of the mitochondrial protein transition pore. The pathophysiological basis for reperfusion arrhythmias is the same intracellular calcium overload as that causing fatal reperfusion injury. Therefore both conditions should not be seen as separate entities but as one and the same process resulting in two different visible effects. Reperfusion arrhythmias could therefore be seen as a potential marker for fatal reperfusion injury.

Impact of ranolazine on ventricular arrhythmias - A systematic review

Ranolazine is a new medication for the treatment of refractory angina. However, except its anti-anginal properties, it has been found to act as an anti-arrhythmic. The aim of our systematic review is to present the existing data about the impact of ranolazine in ventricular arrhythmias. We searched MEDLINE and Cochrane databases as well clinicaltrials.gov until September 1, 2017 to find all studies (clinical trials, observational studies, case reports/series) reported data about the impact of ranolazine in ventricular arrhythmias. Our search revealed 14 studies (3 clinical trials, 2 observational studies, 8 case reports, 1 case series). These data reported a beneficial impact of ranolazine in ventricular tachycardia/fibrillation, premature ventricular beats, and ICD interventions in different clinical settings. The existing data highlight the anti-arrhythmic properties of ranolazine in ventricular arrhythmias.

The Oxygen Paradox, the French Paradox, and age-related diseases

A paradox is a seemingly absurd or impossible concept, proposition, or theory that is often difficult to understand or explain, sometimes apparently self-contradictory, and yet ultimately correct or true. How is it possible, for example, that oxygen "a toxic environmental poison" could be also indispensable for life (Beckman and Ames Physiol Rev 78(2):547-81, 1998; Stadtman and Berlett Chem Res Toxicol 10(5):485-94, 1997)?: the so-called Oxygen Paradox (Davies and Ursini 1995; Davies Biochem Soc Symp 61:1-31, 1995). How can French people apparently disregard the rule that high dietary intakes of cholesterol and saturated fats (e.g., cheese and paté) will result in an early death from cardiovascular diseases (Renaud and de Lorgeril Lancet 339(8808):1523-6, 1992; Catalgol et al. Front Pharmacol 3:141, 2012; Eisenberg et al. Nat Med 22(12):1428-1438, 2016)?: the so-called, French Paradox. Doubtless, the truth is not a duality and epistemological bias probably generates apparently self-contradictory conclusions. Perhaps nowhere in biology are there so many apparently contradictory views, and even experimental results, affecting human physiology and pathology as in the fields of free radicals and oxidative stress, antioxidants, foods and drinks, and dietary recommendations; this is particularly true when issues such as disease-susceptibility or avoidance, "healthspan," "lifespan," and ageing are involved. Consider, for example, the apparently paradoxical observation that treatment with low doses of a substance that is toxic at high concentrations may actually induce transient adaptations that protect against a subsequent exposure to the same (or similar) toxin. This particular paradox is now mechanistically explained as "Adaptive Homeostasis" (Davies Mol Asp Med 49:1-7, 2016; Pomatto et al. 2017a; Lomeli et al. Clin Sci (Lond) 131(21):2573-2599, 2017; Pomatto and Davies 2017); the non-damaging process by which an apparent toxicant can activate biological signal transduction pathways to increase expression of protective genes, by mechanisms that are completely different from those by which the same agent induces toxicity at high concentrations. In this review, we explore the influences and effects of paradoxes such as the Oxygen Paradox and the French Paradox on the etiology, progression, and outcomes of many of the major human age-related diseases, as well as the basic biological phenomenon of ageing itself.

Rat Models of Ventricular Fibrillation Following Acute Myocardial Infarction

A number of animal models have been designed in order to unravel the underlying mechanisms of acute ischemia-induced arrhythmias and to test compounds and interventions for antiarrhythmic therapy. This is important as acute myocardial infarction (AMI) continues to be the major cause of sudden cardiac death, and we are yet to discover safe and effective treatments of the lethal arrhythmias occurring in the acute setting. Animal models therefore continue to be relevant for our understanding and treatment of acute ischemic arrhythmias. This review discusses the applicability of the rat as a model for ventricular arrhythmias occurring during the acute phase of AMI. It provides a description of models developed, advantages and disadvantages of rats, as well as an overview of the most important interventions investigated and the relevance for human pathophysiology.

Ranolazine: Electrophysiologic Effect, Efficacy, and Safety in Patients with Cardiac Arrhythmias

Ranolazine is currently approved as an antianginal agent in patients with chronic angina (class IIA). Ranolazine exhibits antiarrhythmic effects that are related to its multichannel blocking effect, predominantly inhibition of late sodium (late INa) current and the rapid potassium rectifier current (IKr), as well as ICa, late ICa, and INa-Ca. It also suppresses the early and delayed after depolarizations. Ranolazine is effective in the suppression of atrial and ventricular arrhythmias (off-label use) without significant proarrhythmic effect. Currently, ongoing trials are evaluating the efficacy and safety of ranolazine in patients with cardiac arrhythmias; preliminary results suggest that ranolazine, when used alone or in combination with dronedarone, is safe and effective in reducing atrial fibrillation. Ranolazine is not currently approved by the US Food and Drug Administration as an antiarrhythmic agent.

Ranolazine in Cardiac Arrhythmia

Ranolazine utilization in the management of refractory angina has been established by multiple randomized clinical studies. However, there is growing evidence showing an evolving role in the field of cardiac arrhythmias. Multiple experimental and clinical studies have evaluated the role of ranolazine in prevention and management of atrial fibrillation, with ongoing studies on its role in ventricular arrhythmias. In this review, we will discuss the pharmacological, experimental, and clinical evidence behind ranolazine use in the management of various cardiac arrhythmias.

[Electrical storm in the emergency room: clinical pathways]

In patients with structural heart disease, occurrence of an electrical storm (ES) is associated with increased mortality acutely and during medium term follow-up. Depending on the underlying heart disease and baseline type of arrhythmia, different clinical pathways have to be followed to reach sustained freedom from ventricular arrhythmia recurrences. Trigger elimination, sympathetic blockade (initially using betablockers and sedation), antiarrhythmic therapy with amiodarone and catheter ablation, treatment of heart failure and invasive hemodynamic support are cornerstones of the treatment. We present an algorithm which may help to organize an optimized treatment for each ES patient, implementing invasive treatment options like coronary angioplasty, catheter ablation and invasive circulatory support. Further studies are necessary to evaluate medium term outcome of such a structured therapy.

Does sex influence the incidence or severity of reperfusion-induced cardiac arrhythmias?

Whether sex affects the acute phase of myocardial ischemia in experimental animal models is currently being debated. Our purpose was to determine if sex influences either the incidence or severity of reperfusion-induced arrhythmias resulting from a brief coronary occlusion. Male and female Sprague–Dawley rats were assigned to the study. Anesthetized animals were subjected to a 5-minute coronary artery occlusion followed by 5 minutes of reperfusion. Mortality differed by sex: 10/27 (37%) of males died due to VT/VF while only 1/16 females (6%) died due to VT/VF (p = 0.033). Quantitative analysis of the electrocardiogram was performed on data acquired from 17 male and 15 female survivors. Analysis showed no other significant differences in ventricular arrhythmias between the two groups. Conclusion: Lethal reperfusion-induced arrhythmias led to a higher mortality in male rats versus female rats. Among survivors there was no difference in any other arrhythmic parameters measured.

Adjuvant antiarrhythmic therapy in patients with implantable cardioverter defibrillators

The risk of sudden cardiac death from ventricular fibrillation or ventricular tachycardia in patients with cardiomyopathy related to structural heart disease has been favorably impacted by the wide adaptation of implantable cardioverter defibrillators (ICDs) for both primary and secondary prevention. Unfortunately, after ICD implantation both appropriate and inappropriate ICD therapies are common. ICD shocks in particular can have significant effects on quality of life and disease-related morbidity and mortality. While not indicated for primary prevention of ICD therapies, beta-blockers and antiarrhythmic drugs are a cornerstone for secondary prevention of them. This review will summarize our current understanding of adjuvant antiarrhythmic drug therapy in ICD patients. The review will also discuss the roles of nonantiarrhythmic drug approaches that are used in isolation and in combination with antiarrhythmic drugs to reduce subsequent risk of ICD shocks.

Efficacy and safety of ranolazine in patients with chronic stable angina

Chronic stable angina (CSA) impairs patient quality of life, is associated with increased patient mortality, and is a prominent symptom of coronary artery disease (CAD), the latter being prevalent worldwide in patients. Currently, therapeutic options for patients with CSA include β-blockers, calcium channel blockers, nitrates, and ranolazine. Ranolazine is a first-in-class piperazine derivative that inhibits the late inward sodium current in cardiac cells and is considered an effective and safe option for treating patients with CSA. As with any first-in-class agent, it is important for the practitioner to be familiar with the safety profile of the drug. Therefore, the objective of our article is to review safety data on the use of ranolazine in patients with CSA. Clinical data show that ranolazine is well tolerated: major treatment-associated adverse events include dizziness, nausea, headache, and constipation. Ranolazine treatment is also associated with QTc-interval prolongation; however, QTc-interval prolongation with ranolazine does not appear to have clinical consequences-in fact, several studies suggest that ranolazine therapy may have an antiarrhythmic effect in patients. Notably, ranolazine is hemodynamically neutral in that it exerts its antianginal effect without significantly impacting patient heart rate or blood pressure. In addition, small decreases in glycosylated hemoglobin levels have been seen in patients with type 2 diabetes mellitus. Overall, ranolazine (in doses of 500 mg and 1000 mg, twice daily) is a safe and effective option for monotherapy or add-on therapy to reduce anginal symptoms in patients with CSA.

Mechanisms of ranolazine's dual protection against atrial and ventricular fibrillation

Coronary artery disease and heart failure carry concurrent risk for atrial fibrillation and life-threatening ventricular arrhythmias. We review evidence indicating that at therapeutic concentrations, ranolazine has potential for dual suppression of these arrhythmias. Mechanisms and clinical implications are discussed.

Wenxin Keli suppresses ventricular triggered arrhythmias via selective inhibition of late sodium current

BACKGROUND

Wenxin Keli is a popular Chinese herb extract that approximately five million Asians are currently taking for the treatment of a variety of ventricular arrhythmias. However, its electrophysiological mechanisms remain poorly understood.

METHODS AND RESULTS

The concentration-dependent electrophysiological effects of Wenxin Keli were evaluated in the isolated rabbit left ventricular myocytes and wedge preparation. Wenxin Keli selectively inhibited late sodium current (INa) with an IC50 of 3.8 ± 0.4 mg/mL, which was significantly lower than the IC50 of 10.6 ± 0.9 mg/mL (n = 6, P < 0.05) for the fast INa. Wenxin Keli produced a small but statistically significant QT prolongation at 0.3 mg/mL, but shortened the QT and Tp-e interval at concentrations ≥ 1 mg/mL. Wenxin Keli increased QRS duration by 10.1% from 34.8 ± 1.0 ms to 38.3 ± 1.1 ms (n = 6, P < 0.01) at 3 mg/mL at a basic cycle length of 2,000 ms. However, its effect on the QRS duration exhibited weak use-dependency, that is, QRS remained less changed at increased pacing rates than other classic sodium channel blockers, such as flecainide, quinidine, and lidocaine. On the other hand, Wenxin Keli at 1-3 mg/mL markedly reduced dofetilide-induced QT and Tp-e prolongation by attenuation of its reverse use-dependence and abolished dofetilide-induced early afterdepolarization (EAD) in four of four left ventricular wedge preparations. It also suppressed digoxin-induced delayed after depolarization (DAD) and ventricular tachycardias without changing the positive staircase pattern in contractility at 1-3 mg/mL in a separate experimental series (four of four).

CONCLUSIONS

Wenxin Keli suppressed EADs, DADs, and triggered ventricular arrhythmias via selective inhibition of late INa.

Pathological role of serum- and glucocorticoid-regulated kinase 1 in adverse ventricular remodeling

BACKGROUND

Heart failure is a growing cause of morbidity and mortality. Cardiac phosphatidylinositol 3-kinase signaling promotes cardiomyocyte survival and function, but it is paradoxically activated in heart failure, suggesting that chronic activation of this pathway may become maladaptive. Here, we investigated the downstream phosphatidylinositol 3-kinase effector, serum- and glucocorticoid-regulated kinase-1 (SGK1), in heart failure and its complications.

METHODS AND RESULTS

We found that cardiac SGK1 is activated in human and murine heart failure. We investigated the role of SGK1 in the heart by using cardiac-specific expression of constitutively active or dominant-negative SGK1. Cardiac-specific activation of SGK1 in mice increased mortality, cardiac dysfunction, and ventricular arrhythmias. The proarrhythmic effects of SGK1 were linked to biochemical and functional changes in the cardiac sodium channel and could be reversed by treatment with ranolazine, a blocker of the late sodium current. Conversely, cardiac-specific inhibition of SGK1 protected mice after hemodynamic stress from fibrosis, heart failure, and sodium channel alterations.

CONCLUSIONS

SGK1 appears both necessary and sufficient for key features of adverse ventricular remodeling and may provide a novel therapeutic target in cardiac disease.

The effect of acute versus delayed remote ischemic preconditioning on reperfusion induced ventricular arrhythmias

INTRODUCTION

The effect of remote ischemic preconditioning (RIPC) on arrhythmias in in vivo models is unknown. Our purpose was to determine effects of both acute and delayed RIPC on arrhythmias.

METHODS AND RESULTS

In the acute protocol anesthetized open chest rats were exposed to 5 minutes of proximal left coronary artery occlusion (CAO) and 10 minutes of reperfusion. Rats were either untreated (ischemia/reperfusion, IR group, n = 17) or received RIPC (n = 14) with 5 minutes bilateral femoral occlusions followed by 5 minutes of reperfusion times 3, started 30 minutes before CAO. At reperfusion, onset of ventricular tachycardia (VT) was delayed in RIPC group (25.7 seconds) versus IR (8.8 seconds; P = 0.04). Number of episodes of VT was 17.0 in IR versus 3.0 in the RIPC group (P = 0.01) and duration of VT was 54.1 seconds in IR versus 4.9 seconds in RIPC (P = 0.019). Number of ventricular premature complexes (VPC) was 26.0 in IR and 10.0 in RIPC rats (P = 0.04). Levels of reperfusion injury salvage kinases (RISK), that is, phospho-Akt and phospho-p70S6 in the risk area of IR and RIPC hearts were similarly higher compared to the nonischemic areas both at 1 and 10 minutes into reperfusion. Delayed RIPC was induced on day 1 and on day 2, myocardial IR was induced. Delayed RIPC did not affect VT or VPC.

CONCLUSION

Acute RIPC of the lower limbs induced a powerful delay in/and reduction in IR induced ventricular arrhythmias, but without evoking the RISK pathway; a late protective phase of RIPC on arrhythmias did not occur.

Absence of actions of commonly used Chinese herbal medicines and electroacupuncture on myocardial infarct size

BACKGROUND

Some studies have suggested that certain Chinese herbal remedies and acupuncture could limit ischemia/reperfusion damage. We sought to determine whether the commonly used single herb Danshen (DS), either alone or in combination with Jiang Xiang (JX), or electroacupuncture (EA) reduces myocardial infarct size.

METHODS

An anesthetized rat model of proximal left coronary artery occlusion (30 minutes) and reperfusion (180 minutes) was used to measure infarct size (triphenyltetrazolium chloride) and ischemic risk zone (blue dye technique). Rats were either untreated (saline) or received an infusion of DS or DS + JX, starting 30 minutes prior to coronary occlusion. In a separate protocol, rats were untreated, received static needle (ND) placement without stimulation or EA at P5-P6 acupuncture points in the rat forearm starting 5 minutes before occlusion and lasting for 40 minutes, or starting 30 minutes before occlusion and lasting for 90 minutes.

RESULTS

In the herbal experiments, myocardial infarct size expressed as a fraction of the ischemic risk zone was 0.43 ± 0.06 in controls, 0.39 ± 0.05 in the DS group, and 0.42 ± 0.04 in the Danshen + JX groups (P = not significant [NS]). In the acupuncture study, there was no significant difference in infarct size as a fraction of the risk zone among the control group (0.38 ± 0.04), the ND group (0.47 ± 0.04), or the EA group (0.32 ± 0.05). When EA was started 30 minutes prior to coronary occlusion and continued for 30 minutes into reperfusion, infarct size was 0.41 ± 0.07 in controls and 0.38 ± 0.10 in EA (P = NS). Neither herbs nor EA altered heart rate or blood pressure. In a separate study of 5 minutes of coronary occlusion plus reperfusion, EA failed to reduce ventricular arrhythmias.

CONCLUSION

Our studies do not suggest a cardioprotective effect of DS or DS + JX or EA in an experimental model of myocardial ischemia/reperfusion.

A focus on antiarrhythmic properties of ranolazine

Ranolazine is an antianginal drug that inhibits a number of ion currents that are important for the genesis of transmembrane cardiac action potential. It was initially developed as an antianginal agent but was found to additionally exert antiarrhythmic actions, due to its multichannel-blocking properties. In recent years, several studies about the antiarrhythmic properties of ranolazine were conducted, demonstrating the beneficial effects of this drug in both atrial and ventricular arrhythmias, such as atrial fibrillation, ventricular premature beats, ventricular tachycardia, torsades de pointes, and ventricular fibrillation. Our aim is to briefly review the main points of these studies, most more experimental than clinical.