Small vessels in the brain and heart: How similar are they?

Abstract

AbstractBackgroundIn the brain and heart alike blood vessels are end arteries and their occlusion results in anaemic infarct with high mortality and severe morbidity in a high proportion of survivors. The role of collateral circulation and early recanalization is crucial in both contexts. Ischaemic preconditioning, reperfusion injury and haemorrhagic transformation are three key pathophysiological processes in both organs and the morphological and molecular processes at the level of microcirculation are fundamental to understand and therapeutically modulate the effects of ischaemia.MethodThe morphology of small vessels in brain and heart are compared based on published literature and pathologically assessed cases. The similarities and differences are related to the morphological and molecular consequences of hypoperfusion and vascular occlusion at the level of small vessels and microcirculation. In a case series, we retrospectively analysed the clinical data of 158 patients in a regional centre for acute stroke care. For clinico‐pathological analysis 98 cases (age 62±6.5y) were suitable.ResultAlthough small vessels and the microcirculation share morphological and molecular similarities in health and in response to ischaemic challenge, the specific and unique features of the blood‐brain barrier and the neurovascular unit in the brain are major differences, with implications for drug transfer to the ischaemic parenchyma. Haemorrhagic transformation accelerates the secondary progression of stroke and indicates higher risk of adverse outcome. Neurodegenerative changes impair the microcirculation and, vice versa, microcirculatory damage and dysfunction may trigger and accelerate the neurodegenerative cascade. Vascular and neurodegenerative mechanisms in dementia usually coexist. The morphological patterns of infarct evolution and healing are rather different in the brain and the heart, which also applies to the characteristics of the inflammatory cell composition.ConclusionOur findings underline the importance of post‐mortem pathological examination in the era of advanced imaging and laboratory diagnostic techniques. The fundamental differences in the histomorphology and in the sequence of cellular and molecular events during ischaemia and reperfusion in brain and heart indicate that adaptations of findings in cardiology and clinical neuroscience should be made with caution.