Heart and brain interactions: is small vessel disease a link?

Central Figure Legend: Heart and brain microvascular disorders. Left panel and top: these microvascular disorders occur mostly in women and involve inflammation and oxidative stress. Central panel: coronary microvascular disfunction (CMD). Mostly middle-aged women, causes myocardial ischaemia, recurrent angina, shortness of breath, frequent emergency department visits, hospitalizations, and reduced quality of life (QOL). Key functional changes: reduced coronary endothelial dependent vasodilation (EDVD), enhanced vasoconstriction, spasm, limited coronary flow reserve (CFR). Prevalent in hypertension, cardiomyopathies, diabetes, hypercholesterolaemia, metabolic syndrome, chronic kidney disease, and sedentary lifestyles (not shown). Cardiac imaging features: reduced TIMI (thrombolysis in myocardial infarction) flow grade, 'slow flow' on invasive coronary angiography; reduced coronary blood flow (Doppler velocity) or cardiac magnetic resonance imaging (cMRI) as myocardial perfusion reserve index (MPRI) to adenosine, also small scar by late gadolinium (LGE). Is reversible. Right panel: cerebral small vessel disease (CSVD). Mostly older women, closely correlated with age; prevalence increases from ∼5% at age 50 to nearly 100% by age 90. Causes gait and balance disorders, increased risk of falls, stroke, decreased QOL, and contributes to cognitive decline or directly disrupts motor pathways. Brain imaging features: magnetic resonance imaging (MRI) as white matter hyperintensities (WMH), cerebral microbleeds (CMB), lacunar infarctions (LI), enlarged perivascular spaces (EPVS), and brain atrophy. Functional MRI and transcranial Doppler. Different CSVD imaging features have different characteristics. The brain parenchymal lesions can be either ischaemic or haemorrhagic. Various aetiological classifications have been proposed [e.g. atherosclerosis, cerebral amyloid angiopathy, inherited or genetic (CADASIL, CARASIL, Fabry's disease, COL4A1 mutations etc.), inflammatory and immune-mediated, venous collagenosis, other (post radiation angiopathy, non-amyloid microvessel degeneration in Alzheimer's disease)]. Not reversible at present.