The novel severe acute respiratory coronavirus-2 (SARS-Cov-2) constitutes the causative agent of coronavirus disease-2019 (COVID-19). Several mechanisms have been proposed regarding the development of cardiovascular complications during and after acute COVID-19 infection. COVID-19, caused by SARS-CoV-2, has emerged as one of the deadliest pandemics in modern history. Several clinical and pathophysiologic mechanisms have been proposed for development of cardiovascular complications during and after acute COVID-19 infection. The myocardial injury in patients with COVID-19 has been attributed to coronary spasm, microthrombi formation, plaque rupture, hypoxic injury or cytokine storm disposing the same pathophysiology with the three clinical variants of Kounis syndrome. One of the main proposed mechanisms for development of cardiovascular complications is the angiotensin converting enzyme 2 (ACE2) and its interactions with the renin-aldosterone system (RAAS) and the kinin-kallikrein system (KKS). The ACE2 receptors are expressed throughout the human body located mainly in heart, blood vessels endothelium, lungs, intestines, testes and neurons. The SARS-CoV-2 directly invades the endothelial cells that contain ACE2 receptors and constitutes the main pathway through which the virus enters the endothelial cells. This leads to downregulation of the ACE2 receptors and causes angiotensin II accumulation leading to prothrombotic effects such as hemostatic imbalance via activation of the coagulation cascade, impaired fibrinolysis, thrombin generation, vasoconstriction, endothelial and platelet activation, and pro-inflammatory cytokine release. Indeed, angiotensin I exerts no direct biological function except that its high levels can stimulate catecholamine production. It is metabolized to its biologically active byproduct angiotensin II, a potent vasoconstrictor, by angiotensin converting enzyme (ACE) through cleavage of the two terminal amino acids. SARS-CoV-2 infection prevents the counterbalancing action of the KKS system that normally causes vasodilation and regulates tissue repair, inflammation, cell proliferation, and platelet aggregation. All this cascade leads to the following cardiovascular events: cardiac arrhythmias, cardiac arrest, cardiomyopathy, cytokine storm, heart failure, ischemic myocardial injuries and microvascular disease, Kounis syndrome, long COVID, myocardial fibrosis, myocarditis, new onset hypertension, pericarditis, postural orthostatic tachycardia syndrome (POTS), pulmonary hypertension, stroke, Takotsubo Syndrome, venous thromboembolism and thrombocytopenia. In this narrative review we describe and elucidate when and how the COVID-19 affects the human cardiovascular system, in various areas on the human body that are vulnerable in every category of patients including children and athletes.

The most frequent cause of cardiac failure globally is ischemic heart disease, with chemothera-py-related cardiovascular side effects emerging as the second most frequent cause. Cancer therapy can result in acute cardiac events, such as coronary artery spasm, acute myocardial infarction, thromboembolism, myocarditis, bradycardia, tachyarrhythmias, atrio-ventricular blocks, QT pro-longation, torsades de pointes, pericardial effusion and hypotension, as well as chronic conditions, such as hypertension, systolic and diastolic left ventricular dysfunction presenting clinically as heart failure or cardiomyopathy. In cardio-oncology, when referring to cardiac toxicity and cardiovas-cular hypersensitivity, there is a great deal of misunderstanding. When a dose-related cardiovas-cular side effect continues even after the causative medication is stopped, it is referred to as cardi-otoxicity. A fibrotic response is the ultimate outcome of cardiac toxicity, which is defined as a dose-related cardiovascular adverse impact that lasts even after the causative treatment is stopped. Cardiotoxicity can occur after a single or brief exposure. On the other hand, the term cardiac or cardiovascular hypersensitivity describes an inflammatory reaction that is not dose-dependent, can occur at any point during therapy, even with very low medication dosages, and can show up as Kounis syndrome. It may also be accompanied by anti-drug antibodies and tryptase levels. In this comprehensive review, we present the current views on cardiac toxicity and cardiovascular hypersensitivity, together with the reviewed cardiac literature on the chemotherapeutic agents inducing hypersensitivity reactions. Cardiac hypersensitivity seems to be the pathophysiologic basis of coronary artery spasm, acute coronary syndromes such as Kounis syndrome and myocardi-tis caused by cancer therapy.

The Kounis syndrome (KS) is an acute coronary syndrome triggered by allergic or hypersensitiv-ity reactions. Incidence rates vary, with studies reporting 19.4 per 100.000 among all admissions and 3.4% among allergy patients. This review explores the expanding understanding of KS, en-compassing various manifestations, and focusing on both clinical data and forensic findings useful in performing the diagnosis. The pathophysiology of this syndrome involves a complex in-terplay between allergic reactions and the cardiovascular system. Mast cell activation, histamine release, leukotrienes, cytokines, and platelet activation can contribute to the coronary events. A classification system with three types (Allergic Angina, Allergic Myocardial Infarction, Allergic Stent Thrombosis) aids in categorizing presentations. The diagnosis of KS relies on clinical presentation, laboratory findings and imaging. Post mortem assessment of KS is based on the in-tegration of circumstantial data, autopsy and histological findings. Biochemical and immuno-histochemical analyses also contribute to post-mortem diagnosis. In conclusion, a combined, multidisciplinary approach, should be gained to ease diagnostic pro-cess which is crucial for forensic practitioners in confirming KS occurrence.