Acute myocarditis complicated with permanent complete atrioventricular block caused by Escherichia coli bacteremia: A rare case report

Abundant Neutrophil-Initiated Acute Myocardial Injury Following Coxsackievirus A6 Infection

Coxsackievirus A6 (CVA6) is currently considered as a predominant pathogen of hand, foot, and mouth disease (HFMD), and is occasionally linked to myocardial injury. We first established a mouse model of CVA6-induced myocardial injury. Next, we analyzed the immune cell phenotypes CVA6-infected mice hearts by fluorescence-activated cell sorting, and found that CVA6 led to massive neutrophils infiltration, suggesting their potential link with the occurrence of myocardial injury. We further used either αGr-1 or αLy6G antibody to deplete neutrophils, and found that neutrophil-depleted animals showed decreased cardiac enzymes, lower degree of pathology in hearts, and reduced inflammatory cytokine production compared to isotype controls. Finally, we confirmed the involvement of neutrophils in myocardial injury of clinical patients with severe HFMD. Our study suggests that excessive neutrophils contribute to myocardial injury caused by CVA6 infection, which provides new insights into myocardial injury during the development of HFMD severity and the outcome of immune cell-mediated therapies.

Transient complete atrioventricular block and ST-segment elevation induced by coronary vasospasm due to iatrogenic hyperkalemia: a case report

Background

Hyperkalemia and acute coronary syndrome are not only all responsible for syncope related to complete atrioventricular block, but also share parts of electrocardiogram manifestations. Additionally, they influence each other.

Case presentation

A 32-year-old Chinese man presented with severe hypokalemia (1.63 mmol/l) at midnight in the emergency room. He developed unexpected rebound hyperkalemia (7.76 mmol/l) after 18 hours of oral and intravenous potassium chloride supplementation at a concentration of about 10 g/day and a rate of 10 mmol/hour. Subsequently, the patient complained of chest discomfort and dyspnea, followed by syncope for several minutes, approximately 2 hours after potassium reduction treatment had been started. The instant electrocardiogram showed complete atrioventricular block and elevated ST segment in the inferolateral leads, which resolved 15 minutes later, before hyperkalemia was corrected. Combined with mild coronary stenosis and negative myocardial injury markers, transient complete atrioventricular block induced by coronary vasospasm due to iatrogenic hyperkalemia was diagnosed. Normal urine potassium excretion, acid–base state, and other examinations made the diagnosis of hypokalemic periodic paralysis possible.

Conclusions

Hyperkalemia may provoke acute coronary syndrome, and early coronary angiography is an effective strategy for identifying the direct cause of acute complete atrioventricular block.