**1. Introduction**

Hypertension is the most frequently treated disease in internal medicine. More than 1 billion people worldwide suffer from hypertension. Hypertension leads to cardiovascular end-organ damage increasing morbidity and mortality and is related with high costs to society, making this disease an important public health challenge. Sonography is a crucial diagnostic tool in the evaluation of a hypertensive patient. It is used both for the search of secondary forms of hypertension and for the identification of hypertensive end organ damage. There are several ultrasound examinations that may be warranted in hypertension. *Abdominal ultrasound* is recommended by several guidelines for the basic diagnostic workup in every newly diagnosed hypertensive patient. *Doppler sonography of the renal arteries* is reasonable only in a subset of hypertensives that are at increased risk of renal artery stenosis. *Echocardiography* is able to reveal cardiac end organ damage in terms of hypertensive heart disease. *Ultrasound of the carotid arteries* is frequently used to detect and evaluate in the case of hypertension-induced vascular end organ damage. The assessment of the *intima-media thickness* allows the detection of early stages of atherosclerotic wall changes. Prior to any structural vascular damage that may be visualized by ultrasound techniques, hypertension leads to functional changes of the endo‐ thelium, called endothelial dysfunction. Endothelial dysfunction encompasses a variety of changes in vascular function including a reduced endothelium-dependent vasodilation. This can be diagnosed by sonography measuring the diameter changes of the brachial artery in response to predefined endothelial stimuli. *Flow-mediated dilation* in response to hyperemia is regarded as the gold-standard in the non-invasive assessment of endothelial dysfunction. To date, it is rather used scientifically than in daily clinical practice. The present chapter provides

© 2013 Pagonas et al.; licensee InTech. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2013 Pagonas et al.; licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

an overview on the practical performance of all of these ultrasound techniques in the approach to hypertension.

arteries. Renal cell carcinomas as a rare cause of hypertension are depicted as a well delimitable structure from the surrounding tissue. Usually they can be depicted via ultrasound when they exceed 1 cm. With increasingly size there is an increase in their inhomogeneity, so that it is

Diagnostic Use of Sonography in the Evaluation of Hypertension

http://dx.doi.org/10.5772/56171

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In the screening of secondary forms of hypertension abdominal ultrasound plays also a role in the depiction of the adrenal glands. For this purpose a detailed knowledge of the local anatomy is required. The adrenal glands are located within the retroperitoneum. The left adrenal gland, lacking the acoustic window of the liver and being obscured by air in the stomach, is inherently more difficult to scan than the right adrenal gland. On the right side, the right kidney and the inferior vena cava are landmarks for the examination of adrenal glands, whereas on the left side the aorta, the lower pole of the spleen and the upper pole of the kidney are points of orientation. The right adrenal gland is usually scanned with a right transcostal scan or a subcostal flank scan or oblique subcostal scan. On the left side it is better to use an intercostal flank scan through the spleen. The normal sized adrenal glands are only visible with trained examination techniques and by using high resolution technology, whereas enlarged adrenal glands are detectable in a high percentage of cases. Thirty percent of cases of primary aldosteronism are caused by adrenal adenomas. Seventy percent of cases are caused by adrenal hyperplasia. There are rare cases of adrenal carcinoma and the autosomal dominant condition of glucocorticoid remediable aldosteronism [2]. The micronodular hyperplasia is not possible to be detected via sonography. Adrenal adenomas have a round to oval shape and are uniformly hypoechoic with smooth margins, although some lesions have scalloped borders (polycyclic). Adenomas occasionally have an inhomogeneous appearance. Autopsy statistics indicate that they are quite common (10–20%), but most adenomas (90%) produce no endocrine symptoms, they are silent and too small to be detected by ultrasound. In one study the average size of adenomas was reported to be 1.5 cm, although they may exceed 5 cm in diameter. In a small percentage of patients adenomas are bilateral. Functioning and nonfunctioning adeno‐ mas are indistinguishable by their sonographic features [3]. Thus, ultrasound is not a sufficient test in the morphologic diagnosis of Conn syndrome. Upon the detection of a high aldosteroneto-renin ratio and after a confirmation test (e.g. suppression after administration of sodium chloride) the use of a CT or MRT scan is indicated. On the other hand, the detection of a unilateral adrenal mass seen in the ultrasound should be followed by a laboratory evaluation

Phaeochromocytoma, a tumor of the adrenal medulla, is a rare secondary cause of hyperten‐ sion (0.2 – 0.4% of all cases of elevated blood pressure) with an estimated annual incidence of 2 – 8 per million population.[4]. It can be inherited or acquired. Hypertension occurs in about 70% of all cases of phaeochromocytoma, being stable or paroxysmal in approximately equal proportions. The diagnosis is based on establishing an increase in plasma or urinary catechol‐ amines or their metabolites (e.g. (nor-) metanephrines). Following the appearance of clinical symptoms (hypertension and tachycardia caused by increased catecholamine secretion), pheochromocytoma can be detected in 80-90% of cases via abdominal ultrasound. Most pheochromocytomas are already several centimeters in diameter when diagnosed. They have smooth margins, a round shape, and an inhomogeneous or complex echo structure. Hypoe‐

possible to detect areas of liquefied necrosis for example.

for the evaluation of Conn-Syndrome.
