The brain-heart connection; a round trip

Abstract

Over the past months three interesting cardiovascular findings have been published: 1) Transient ischaemic attacks (TIAs) may increase the risk for later heart attack, 2) early morning heart attacks may be more severe, and 3) too much television may increase future cardiovascular risk for children. Regarding finding 1, a TIA appears to double the risk for a heart attack later according to a study published online in the journal Stroke: mortality associated with a myocardial infarction after TIA was 3 times that of patients who did not have a myocardial infarction. Regarding finding 2, it was reported that a heart attack in the morning is likely to be more severe than having one at any other time of day, according to a study published online in the journal Heart. This phenomenon may be due to the changes in the body's blood pressure, hormone levels and metabolic rates that naturally occur when a person wakes up. Regarding finding 3, it was shown that young children who spend too much time watching TV or playing computer games have narrower eye arteries than kids who are more physically active, according to an Australian study published online in the journal ATVB (Arteriosclerosis, Thrombosis and Vascular Biology). After adjustment for age, sex, ethnicity, eye colour, axial length, body-mass index, birth weight, and mean arterial blood pressure, the retinal arteriolar caliber in 1500 children who were in the highest tertile of outdoor sporting activities was an average of 2.2 μm wider than those of the children in the lowest tertile of outdoor physical activity (predominantly TV watchers). Although these findings have their own specific implications, the common denominator of these observations is the interaction between the heart and the brain and vice versa. The speciality that deals with the brain-heart connection has become known as neurocardiology. Neurocardiology refers to (patho)physiological interplays of the nervous and cardiovascular systems. Over the past years, there is increasing evidence about brain-heart interaction with major potential implications for treatment of cardiovascular diseases. For instance, cerebrovascular accidents (CVAs) and TIAs are frequently caused by cardiac arrhythmias. In particular atrial fibrillation may result in cognitive disorders preceding the occurrence of transient ischaemic attacks or CVAs. Even in the absence of manifest stroke, atrial fibrillation is a risk factor for cognitive impairment and hippocampal atrophy. Therefore, cognition and measures of structural brain integrity should be considered in the evaluation of novel treatments for atrial fibrillation. On the other hand, cerebrovascular dysfunction may lead to electrocardiographical disorders and cardiac rhythm disturbances. Coronary artery bypass surgery (CABG) has major effects on neuron-cognitive functioning. However, the literature still remains undecided on the role of intra-operative emboli and cognitive decline after surgery. More attention should be focussed on the composition, size and location instead of the absolute number of intra-operative emboli; growing awareness of neuron-cognitive decline in chronic vascular disease patients must challenge both clinicians and investigators. Exercise stimuli may prevent or slow down the cognitive decline in elderly patients with heart failure. In particular, the therapeutic implications in the direct interrelation between the nervous system, the brain and the heart will increasingly become a dominant focus of forthcoming studies. The future of therapeutic approaches in neurocardiology lies both in novel treatment as in applying scientific integrative medical ideas that takes into account concurrent chronic degenerative and vascular disorders and interactions of multiple drug and non-drug treatments. Various patient groups (atrial fibrillation, heart failure, post-CABG) may benefit when the appropriate mechanisms of the interrelation between nervous system, brain and heart will become elucidated. When these relationships are better understood, more appropriate therapeutic measures can be taken to benefit patients with cardiovascular and cerebrovascular diseases.