Fatal non-bacterial thrombotic endocarditis following viperine bite

Changes in attachment and metabolic activity of rat neonatal cardiomyocytes and nonmyocytes caused by Macrovipera lebetina obtusa venom

The Caucasian viper Macrovipera lebetina obtusa (MLO) is one of the most prevalent and venomous snakes in the Caucasus and the surrounding regions, yet the effects of MLO venom on cardiac function remain largely unknown. We examined the influence of MLO venom (crude and with inhibited metalloproteinases and phospholipase A2) on attachment and metabolic activity of rat neonatal cardiomyocytes (CM) and nonmyocytes (nCM), assessed at 1 and 24 h. After exposing both CM and nCM to varying concentrations of MLO venom, we observed immediate cytotoxic effects at a concentration of 100 μg/ml, causing detachment from the culture substrate. At lower MLO venom concentrations both cell types detached in a dose-dependent manner. Inhibition of MLO venom metalloproteinases significantly improved CM and nCM attachment after 1-hour exposure. At 24-hour exposure to metalloproteinases inhibited venom statistically significant enhancement was observed only in nCM attachment. However, metabolic activity of CM and nCM did not decrease upon exposure to the lower dose of the venom. Moreover, we demonstrated that metalloproteinases and phospholipases A2 are not the components of the MLO venom that change metabolic activity of both CM and nCM. These results provide a valuable platform to study the impact of MLO venom on prey cardiac function. They also call for further exploration of individual venom components for pharmaceutical purposes.

Neurologic complications of nonbacterial thrombotic endocarditis

Endocarditis is an inflammatory or infective condition affecting the cardiac valves or endocardium, often associated with serious neurological sequelae. Nonbacterial thrombotic endocarditis (NBTE)-referred to as degenerative, Libman-Sachs, marantic, verrucous, or terminal endocarditis-is a serious but rare cause of valvular heart disease characterized by deposition of sterile vegetations of fibrin and platelet aggregates on the cardiac valves, eventually resulting in life-threatening embolization of these thrombi to the brain, limbs, or visceral organs. NBTE may complicate a heterogeneous group of chronic conditions, predominantly connective tissue and autoimmune disorders, malignancies, and diseases associated with hypercoagulability states. NBTE usually affects the native rather than prosthetic valves, and unlike infective endocarditis (IE), sparing the involved valve function without its destruction. Compared to those seen in IE, vegetations in NBTE are small and friable, thus may easily be dislodged leading to systemic thromboembolism with devastating morbidities and mortality. There are no diagnostic criteria for NBTE, and antemortem diagnosis is challenging. The condition should be suspected in patients with thromboembolic events and vegetations on the cardiac valves on echocardiographic or cardiac imaging studies, in the absence of underlying infection, especially in disorders predisposing to coagulopathy. Early recognition and prompt treatment of the primary underlying disorder is essential. Anticoagulation with heparin or heparinoid products is recommended to prevent recurrent embolism. Surgical intervention is not indicated except in selected patients with life-threatening recurrent embolism.

Cerebrovascular Accident and Snake Envenomation: A Scoping Study

BACKGROUND

Snake envenomation is associated with serious complications including infections, bleeding and, in rare occasions, thrombosis. Previous work by our group examined the association of snakebite and acute myocardial infarction. In this systematic review we aim to assess the clinical characteristics and outcomes of acute cerebrovascular accidents that are reported to be extremely rare complications of snake envenomation.

METHODS

We performed a literature search for reports on stroke associated with snake envenomation between Jan 1995 to Oct 2018, and summarized their characteristics.

RESULTS

Eighty-three published cases were reviewed. 66.3% of the cases were younger than 50 years of age. The mean time for the onset of the symptoms is 23.8±10.9 hours after exposure. 77.1% of the cases found to have ischemic stroke, 20.5% with intra-cranial hemorrhage and both infarction and hemorrhage in 2.4%. Mortality was reported in 16.9% with mean time between onset of the symptoms and death is 4.2 days.

CONCLUSION

Stroke secondary to snake envenomation is a rare but serious complication. Once stroke is suspected, initiating appropriate management is crucial in reducing morbidity and mortality associated with this potentially fatal complication of snake envenomation.

Cardiotoxic effects of the Vipera ammodytes ammodytes venom fractions in the isolated perfused rat heart

The nose-horned viper (Vipera ammodytes ammodytes) is the most venomous European snake. Its venom is known as haematotoxic, myotoxic and neurotoxic but it exerts also cardiotoxic effects. To further explore the cardiotoxicity of the venom we separated it into four fractions by gel filtration chromatography. Three fractions that contain polypeptides (A, B, and C) were tested for their effects on isolated rat heart. Heart rate (HR), incidence of arrhythmias (atrioventricular (AV) blocks, ventricular tachycardia, ventricular fibrillation, and asystolia), coronary flow (CF), systolic, developed and diastolic left ventricular pressure (LVP) were measured before, during, and after the application of venom fractions in three different concentrations. Fraction A, containing proteins of 60-100 kDa, displayed no effect on the rat heart. Fractions B and C disturbed heart functioning in similar way, but with different potency that was higher by the latter. This was manifested by significant decrease of HR and CF, the increase of diastolic, and the decrease of systolic and developed LVPs. All hearts treated with fraction C in the final CF concentrations 22.5 and 37.5 μg/mL suffered rapid and irreversible asystolia without AV blockade. They underwent also ventricular fibrillation and ventricular tachycardia. Fraction B affected hearts only at the highest dose inducing asystolia in all hearts, ventricular fibrillation in 80% and ventricular tachycardia in 70% of the hearts. Venom fraction C induced 71% of all recorded heart rhythm disturbances, significantly more than fraction B, which induced 29%. Most abundant proteins in fraction C were secreted phospholipases A₂ among which the venom component acting on the heart is most probably to be looked for.

Non-bacterial thrombotic endocarditis

Non-bacterial thrombotic endocarditis (NBTE) is a disease characterised by the presence of vegetations on cardiac valves, which consist of fibrin and platelet aggregates and devoid of inflammation or bacteria. NBTE has increasingly been recognised as a condition associated with numerous diseases and a potentially life-threatening source of thromboembolism. NBTE is not a common entity; however it is frequently underestimated, probably due to underlying diseases (cancer, autoimmune disorders, HIV). NBTE is difficult to diagnose and relies on strong clinical suspicion. NBTE is also difficult to manage and each case should be individually managed by identifying and treating the underlying pathology. Surgical intervention is not recommended unless the patient is in acute congestive failure.

Nonbacterial thrombotic endocarditis after lung transplantation

Bacteria-free verrucae has been recognized as a condition associated with several clinical conditions such as bone marrow transplantation, malignant tumors, autoimmune disorders, and acquired immunodeficiency syndrome, but it has not been reported in relation to lung transplantation. We report the case of a patient who underwent bilateral lung transplant and died 3 days later. Histologic examination revealed, among other lesions, the presence of nonbacterial thrombotic endocarditis in the right atrium and mitral and tricuspid valves that was not present in the preoperative echocardiographic studies. Even with transesophageal echocardiography, a reliable detection of vegetations may not be possible. Hypoxigenic pulmonary states developed in the course of lung transplant could be the factor that triggers the interaction between the coagulation system, platelets, and endothelial cells that induce the formation of bacteria-free verrucae.

Multiple thrombotic occlusions of vessels after Russell's viper envenoming

Systemic bleeding due to consumption coagulopathy and thrombocytopenia due to activation of procoagulants is the leading manifestation and cause of death in Russell's viper systemic envenoming. Thrombotic occlusion of the blood vessels is rare in cases of snakebite. In this report, two adult patients with Russell's viper systemic envenoming presented multiple cerebral infarctions, digital gangrenes and ischaemic organs in addition to typical clinical manifestations of bleeding diathesis and renal involvement. Our findings in these two special cases suggest that the venom-induced coagulopathy and endothelium damage, predisposed by toxin-induced vasoconstriction, might be the possible mechanism of multiple thrombotic vascular occlusions in systemic envenoming of Formosan Russell's viper.

Non-bacterial thrombotic (marantic) endocarditis associated with giant-cell arteritis

A patient with giant-cell arteritis and non-bacterial thrombotic (marantic) endocarditis of the mitral valve is described. To our knowledge, this is the first case reported. The importance of revising the diagnosis of infective endocarditis when no pathogen can be demonstrated is emphasized.