Mast cells are present in the cardiovascular system under normal conditions both in the heart and near vasculature, often in spaces close to nerve endings. They perform a variety of necessary functions including participating in the pathway to generate the hormone angiotensin II, which encourages an increase in blood pressure. Mast cells in the heart and vasculature are usually positive for both chymase and tryptase in granules. Mast cells in the cardiovascular system have also been tied to a number of conditions, including atherosclerosis, arrhythmias and aneurysm.
Mast cell patients may experience a number of cardiovascular symptoms or events. 29% of SM patients and at least 20% of MCAS patients report palpitations and supraventricular tachycardia. 31% of patients with mast cell activation disease (MCAS, MMAS, SM) experience episodic or chronic elevation in arterial blood pressure due to mast cell activation. Ventricular fibrillation, cardiac arrest and Kounis Syndrome can occur in mast cell patients due to mast cell activation. Few cases of heart failure in SM patients have been reported.
Kounis Syndrome is an acute coronary syndrome provoked by mast cell mediator release. In one series, ten mast cell patients (5 MCAS, 3 MMAS, 2 ISM) suffered acute coronary syndromes. These patients reported “oppressive” chest pain of the type commonly seen in ischemic cardiac events. The triggers for these events were diverse: venom immunotherapy, mepivacaine, exercise, penicillin, general anesthesia, wasp sting, metamizole and moxifloxacin. In seven patients, the echocardiogram was normal. In the remaining, left ventricular hypertrophy, anteroseptal hypokinesia, medioapical hypokinesia, inferoseptal akinesis, lateral apical akinesia and left ventricular ejection fraction of 40% were found on echo. Only six patients had elevation of troponin, a test commonly used to diagnose heart attack and acute coronary syndromes.
Mast cell mediators exhibit a wide range of effects on the cardiovascular and nervous systems. Mast cell mediators can affect release of norepinephrine by sympathetic nervous system, contributing to arrhythmias. In some instances, release of norepinephrine has been linked to sudden cardiac death, although not linked specifically to mast cell patients. Histamine actually decreases norepinephrine release by binding to H3 receptors on nerve endings.
As mentioned above, mast cells participate in modulating the level of angiotensin II. Mast cells release renin, which leads to the formation of angiotensin II. Angiotensin II then binds to AT1 receptors on sympathetic nerve endings, raising blood pressure. Angiotensin II can also cause arrhythmias without involving the nervous system.
References:
Kolck UW, et al. Cardiovascular symptoms in patients with systemic mast cell activation disease. Translation Research 2016; x:1-10.
Gonzalez-de-Olano D, et al. Mast cell-related disorders presenting with Kounis Syndrome. International Journal of Cardiology 2012: 161(1): 56-58.
Kennedy S, et al. Mast cells and vascular diseases. Pharmacology & Therapeurics 2013; 138: 53-65.