Cardiovascular centre is detected by baroreceptors in the aortic sinuses or carotid sinuses, the cardiovascular centre affects changes to the heart rate by sending a nerve impulse to the cardiac pacemaker (or SA node) via sympathetic fibres (to cause faster and stronger cardiac muscle contraction) and the vagus nerve (to cause slower and less strong cardiac muscle contraction). The cardiovascular centre also increases the stroke volume of the heart (that is, the amount of blood it pumps). These two changes help to regulate the cardiac output, so that a sufficient amount of blood reaches tissue. Hormones like epinephrine and norepinephrine can affect
Heart failure with preserved ejection fraction and lower ejection fractions. Cardiac output is dependent on stroke volume and heart rate. A significant portion (55-77%) of HFpEF patients are unable to increase heart rate to compensate for increased output demand (as in the setting of exercise); this is termed chronotropic incompetence. Combined with the characteristic deficit in stroke volume observed in HFpEF patients, many individuals display poor exercise tolerance. Non-simultaneous contraction of the left and right ventricle, dyssychrony, is present in up to 58% of HFpEF patients. However, dyssynchrony is also common in HFrEF and its role in HFpEF in particular remains obscure. While therapies for dyssynchrony,