HW 01-3 CARDIAC AND VASCULAR MRI IN HYPERTENSION EVALUATION

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Abstract

Chronic hypertension can result in deleterious effects on various vascular organs including the heart and vessels. Cardiovascular magnetic resonance (CMR) has the unique advantage of the ability to assess ventricular volumes and function, valvular abnormalities, vascular pathology, myocardial perfusion and tissue characterization with high accuracy and reproducibility and also avoid the risk of radiation. As this is the case, CMR seems to be an ideal method for comprehensive assessment of patients with systemic hypertension.

In the heart itself, left ventricular hypertrophy with myocardial fibrosis and diastolic or systolic dysfunction of the left ventricle are all important consequences of systemic hypertension that can lead to increased morbidity and mortality. In addition, increased risk of coronary artery disease is another critical end-result of chronic hypertension. CMR can be utilized to assess all of these consequences using cine-MRI, late Gadolinium enhancement, tagging, and myocardial perfusion imaging.

In the arteries, atheromatous plaque and aneurysm formation with the possibility of wall dissection or formation of intramural hematomas are important end-results of longstanding uncontrolled hypertension. With vascular MRI, all of these findings are assessable readily and accurately. Currently, newer techniques such as 4-D flow imaging of the aortic blood flow is being studied for use in understanding the mechanics of blood flow damaging the vessels. Another aspect of vascular MRI that is highly anticipated is the evaluation of pulsed wave velocity. With accurate measurement of vascular flow within any part of the body, and also precise measurement of the distance between various points of the aorta, the propagation velocities of the blood can be assessed with CMR and can be utilized to evaluate the effects of increased central blood pressure, instead of various assumptions using peripheral blood pressure for evaluation of PWV. In addition, evaluation of ventriculo-arterial coupling can be even more accurate when CMR is utilized.

CMR also gives the ability to assess the possibility of secondary hypertension such as renovascular hypertension, primary hyperaldosteronism, pheochromocytoma, or coarctation of aorta.

As these and many other aspects of hypertension and its complications can be easily elucidated with just one diagnostic technique, CMR should be utilized more and more in the evaluation of hypertensive patients especially longstanding or refractory hypertension or subjects who are at high risk of complications of hypertension.

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