This chapter discusses the relationship between kidney injury and heart disease. Cardiac and renal physiology are closely related, and impaired cardiac function can lead to kidney injury and vice versa (see accompanying Hurst’s Central Illustration). Impaired renal function has traditionally been classified into acute kidney injury (AKI) and chronic kidney disease (CKD); the latter syndrome is defined as persistent (>3 months) functional or structural kidney abnormalities. AKI can occur when renal hemodynamics become deranged secondary to acutely impaired cardiac function. Management of cardiovascular disease (CVD) can also cause AKI. For example, contrast-induced AKI can occur in patients undergoing percutaneous interventions, which require imaging, often repeatedly, of the vasculature, and AKI is common after transcatheter aortic valve replacement and after cardiac surgery. Additionally, chronic heart failure can lead to CKD; the pathophysiological mechanisms are incompletely understood. In turn, CKD considerably increases the risk of developing CVD. Autonomic dysfunction, vascular pathology, and cardiac pathology contribute to CVD progression in patients with CKD. Moreover, CKD patients on dialysis have increased risk of pericarditis, infective endocarditis, and cardiac arrhythmias. Management of CVD in patients with CKD requires judicious extrapolation of treatment derived from observational studies and with consideration of CKD pathophysiology. Notably, many cardiovascular drugs are eliminated from the body by the kidneys and dose adjustments of some of these drugs are therefore necessary in patients with CKD.
The relationship between impaired cardiovascular function and impaired renal function. Cardiovascular disease and the management of various cardiovascular conditions can result in acute kidney injury. Additionally, chronic heart failure can lead to chronic kidney disease, persistent (>3 months) functional or structural kidney abnormalities; the pathophysiological mechanisms are incompletely understood. Chronic kidney disease, as well as dialysis in patients with chronic kidney disease, can in turn result in cardiovascular disease.
Cardiac and renal physiology are intimately intertwined. Impaired cardiac function can lead to kidney injury and vice versa. Furthermore, many cardiovascular therapeutic interventions may cause renal injury. Impaired renal function is common among patients with heart disease and is one of the strongest predictors of worse outcome for these patients. Reports suggest that renal disease is underdiagnosed among patients with heart disease, which increases the risk of avoidable adverse outcomes.1,2,3,4
Renal Physiology and Important Concepts
The main functions of the kidneys are to maintain water balance and body fluid homeostasis and to eliminate metabolic waste products. This is achieved by filtration of plasma in the glomerulus, as well as by secretion and reabsorption of water and solutes along the renal tubules. An average human filters 150 to 200 L of plasma across the glomeruli and produces 0.5 to 2.5 L of urine per day. Urine output greater than 2.5 L/d is termed polyuria; urine output less than 400 mL/d is termed oliguria; ...