Cerebral hemodynamics in AF :”Irregularly irregular” brain perfusion and risk of “dementia cordis”
No doubt, the heart is a biological wonder with its non-stop pump function. Still, it cannot function as a continuous rotary pump like the electrical motors do. It has no other option but to contract in a pulsatile manner. However, the mean pressure in circulation is fairly constant, flow is kept continuous, and fairly laminar. This is made possible by the built-in elastic pressure in the aorta and the poorly understood but vitally important parameter vascular tone. Aging widens the pulse pressure due to dissipation of vascular tone. Atrial fibrillation adds new bizarre dynamism to this pulsatility and challenges the aortic wall’s competence and compliance further. This is the basic mechanism behind the classical description of an irregularly irregular pulse in AF. The pulse can be so unpredictable, it was originally referred to as acute confusional status of heart (Delirium cordis)
What is the effect of AF on systolic, diastolic, and mean blood pressure?
In AF systolic BP varies considerably from beat to beat. Diastolic BP does show some changes but less obvious. So far mean pressure fluctuations in AF have not been given much significance.
Clinical significance of AF on the brain: Thinking beyond stroke
From a stroke perspective rate and rhythm control did not show much difference. The prime reason for AFFIRM trial not showing benefit with rhythm control was embolic stroke was much more common from sources other than left atrium proper and hence the usage of oral anticoagulants was more important than rhythm control in overall stroke control.
Now, an important study trying to look at this hitherto ignored aspect( Andrea Saglietto, EP Europace, 2021). It raises concern about the impact of AF on long-term cerebral function. Should we restart the debate in favor of rhythm control? No doubt, the pulmonary venous electrophysiologists will be too glad to welcome this concept.
Now, we have new evidence based on near-infrared spectroscopy AF does cause unpredictable beat-to-beat changes in cerebral microcirculation that leads to neurocognitive dysfunction. It is possible there can be a breach in cerebral autoregulation limits in a significant number of post-long RR beats. We may soon look forward to a new entity of “dementia cordis“as a sequel to chronic AF.
1.Andrea Saglietto, Stefania Scarsoglio, Daniela Canova, et al Increased beat-to-beat variability of cerebral microcirculatory perfusion during atrial fibrillation: a near-infrared spectroscopy study, EP Europace, 2021;, euab070,
2.Atrial Fibrillation, Cognitive Decline and Dementia Alvaro Alonso Eur Cardiol. 2016 Aug; 11(1): 49–53. doi: 10.15420/ecr.2016:13:2