[Cardiovascular risk in polycystic kidney disease]

Hypertension is common and occurs in the majority of autosomal dominant polycystic kidney disease (ADPKD) patients prior to loss of kidney function. Hypertension relates to progressive kidney enlargement, and is a significant independent risk factor for progression to end-stage renal disease. The pathogenesis of hypertension in ADPKD is complex and depends on many factors that influence each other. High expression of PKD1 and PKD2 genes is present in the cilia of tubular epithelial cells, in endothelial cells and in vascular smooth muscle cells. Decreased or absent polycystin-1 or -2 expression is associated with abnormal vascular structure and function. PKD1/PKD2 deficiency results in reduced nitric oxide levels, altered endothelial response to shear stress with attenuation in vascular relaxation. Activation of the renin-angiotensin-aldosterone system occurs in ADPKD due to decreased nitric oxide production as well as bilateral cyst expansion and intra-renal ischemia. With increasing cyst size, further activation of the renin-angiotensin-aldosterone system occurs, blood pressure increases and a vicious cycle ensues with enhanced cyst growth and hypertension ultimately leading to end-stage renal disease. Inhibition of the angiotensin-aldosterone system is possible with angiotensin-converting enzyme inhibitors and seems to be the first-line treatment for hypertension in these subjects. As suggested by the HALT-PKD study, an aggressive blood pressure control is safe and recommended and is associated with preservation of kidney function and a reduction in total kidney volume over time. A collaborative multidisciplinary approach between nephrologists and cardiologists is necessary for the monitoring of kidney and heart complications.