Anabolic androgenic steroids and cardiomyopathy: an update

Anabolic androgenic steroids (AAS) include endogenously produced androgens like testosterone and their synthetic derivatives. Their influence on multiple metabolic pathways across organ systems results in an extensive side effect profile. From creating an atherogenic and prothrombotic milieu to direct myocardial injury, the effects of AAS on the heart may culminate with patients requiring thorough cardiac evaluation and multi-disciplinary medical management related to cardiomyopathy and heart failure (HF). Supraphysiological doses of AAS have been shown to induce cardiomyopathy via biventricular dysfunction. Advancement in imaging including cardiac magnetic resonance imaging (MRI) and additional diagnostic testing have facilitated the identification of AAS-induced left ventricular dysfunction, but data regarding the impact on right ventricular function remains limited. Emerging studies showed conflicting data regarding the reversibility of AAS-induced cardiomyopathy. There is an unmet need for a systematic long-term outcomes study to empirically evaluate the clinical course of cardiomyopathy and to assess potential targeted therapy as appropriate. In this review, we provide an overview of the epidemiology, pathophysiology and management considerations related to AAS and cardiomyopathy.

A Rare Culprit of Methemoglobinemia

Methemoglobinemia is a rare cause of hypoxia and can be a diagnostic challenge early in the disease course. The incidence of medication-induced methemoglobinemia is more common than congenital-related methemoglobinemia. The most common cause of methemoglobinemia is exposure to household detergents, illicit drugs, or medications with nitrate or sulfonamide chemical groups. The 2 main medications accounting for up to 45% of medication-induced cases are dapsone and benzocaine. We report a case of hypoxia and diarrhea with an arterial blood gas (ABG) showing methemoglobinemia at 26%. Infectious and autoimmune workup were negative. Methemoglobinemia level returned to normal level within 2 weeks of hydrochlorothiazide discontinuation, suggesting medication-induced methemoglobinemia at appropriate hypertension dosage. In this case, there was an acute rise in methemoglobin levels following initiation of an hydrochlorothiazide-losartan combination, which improved following the discontinuation of hydrochlorothiazide. Extensive workup ruled out cytochrome b5 reductase (Cb5R) and Glucose-6-phosphate dehydrogenase (G6PD) deficiency, which raised the suspicion of hydrochlorothiazide-induced methemoglobinemia, as it is part of the sulfa drug family.

A Case Report on Rare Presentation of Sporadic Disease: Dermatomyositis Sine Dermatitis—Diagnosis and Management

Dermatomyositis sine dermatitis (DMSD) is one of the rare idiopathic inflammatory myopathies. Based on predominant symptoms faced by patients, it is classified into 3 types: (1) classic dermatomyositis (DM), where patients have both muscle and skin symptoms; and (2) amyopathic DM, when only skin symptoms present with no muscle involvement. Whereas (3) DMSD has mainly muscle symptoms with muscle antibodies but no skin rashes. There have been only nearly 10 published articles about DMSD proving this disease’s scarcity. At the same time, it shows the importance of discussing the unusual presentation of such a rare disease. Here we present, a 28-year-old woman with worsening proximal muscle weakness. The decreased muscle strength on physical examination and elevated creatinine kinase required more work up for autoimmune disease. Interestingly, on muscle biopsy, anti-melanoma differentiation-associated gene 5 (anti-MDA5) antibody returned positive, and the patient responded well to 3 days course of steroids. The lack of skin involvement, the predominance of muscle symptoms, and positive anti-MDA5 antibody indispensably diagnosed patients with DMSD. The previously published articles have proved the association between anti-NXP-2 antibody and DMSD, which was not seen in our case. The systemic involvement of DMSD can lead to interstitial lung disease, where due to diffuse alveolar damage and pulmonary fibrosis, patients end up requiring intubation and may be associated with higher-level mortality. In our case, chest X-rays and computed tomography (CT) scans were unremarkable for lung involvement, so as no paraneoplastic syndromes were present, which has also been reported in DMSD patients previously.

Distribution and function of the muscarinic receptor subtypes in the cardiovascular system

Muscarinic acetylcholine receptors belong to the G protein-coupled receptor superfamily and are widely known to mediate numerous functions within the central and peripheral nervous system. Thus, they have become attractive therapeutic targets for various disorders. It has long been known that the parasympathetic system, governed by acetylcholine, plays an essential role in regulating cardiovascular function. Unfortunately, due to the lack of pharmacologic selectivity for any one muscarinic receptor, there was a minimal understanding of their distribution and function within this region. However, in recent years, advancements in research have led to the generation of knockout animal models, better antibodies, and more selective ligands enabling a more thorough understanding of the unique role muscarinic receptors play in the cardiovascular system. These advances have shown muscarinic receptor 2 is no longer the only functional subtype found within the heart and muscarinic receptors 1 and 3 mediate both dilation and constriction in the vasculature. Although muscarinic receptors 4 and 5 are still not well characterized in the cardiovascular system, the recent generation of knockout animal models will hopefully generate a better understanding of their function. This mini review aims to summarize recent findings and advances of muscarinic involvement in the cardiovascular system.