Renovascular disease, most commonly caused by fibromuscular dysplasia and atherosclerotic disease, manifests in one of three forms: asymptomatic renal artery stenosis (RAS), renovascular hypertension, and ischemic nephropathy. The atherosclerotic form is especially a progressive condition that can lead to gradual and silent loss of kidney function, making early diagnosis of RAS crucial. Interventional treatment can improve hypertension and preserve kidney function.<\/p>\n
RAS is the most common potentially reversible and treatable cause of secondary hypertension and kidney failure.<\/p>\n
Renal color Doppler ultrasound has been chosen by many institutions as the primary screening tool to detect RAS.<\/p>\n
The renal arteries originate from the sides of the aorta, typically at the upper border of the second lumbar vertebra, angled slightly forward and generally 1-2 cm below the origin of the superior mesenteric artery. The right renal artery starts from the anterolateral direction of the aorta and turns immediately posteriorly, running beneath the inferior vena cava (IVC).<\/p>\n
The left renal artery tends to emerge from the posterolateral surface of the aorta and travels behind the aorta\u2019s surface over the psoas muscle.<\/p>\n
The main renal artery divides into anterior and posterior branches inside or outside the renal hilum, which further divides into segmental and interlobar arteries. The interlobar arteries further split into a network of arcuate arteries, which provide cortical branches extending radially to the periphery and medullary branches feeding the renal pyramids. Renal veins usually follow the course of the arteries, positioned more ventrally.<\/p>\n
The normal waveform of the main renal artery resembles the low-resistance pattern found in the parenchymal organs of the body. The peak systolic velocity (PSV) in the main renal artery and its branches should be less than 120 cm\/s. As the intrarenal arteries penetrate the kidney, the velocity gradually decreases. The resistance index (RI) measures the degree of intrarenal arterial impedance and is calculated using the following formula: ([PSV \u2013 end-diastolic velocity] \/ PSV).<\/p>\n
Renal Doppler, one of the advanced ultrasound methods, is performed quite easily. No preparation process is required. The patient is laid on the examination table, and the area to be scanned is applied with gel by the radiologist. This gel facilitates the smooth movement of the ultrasound probe over the skin. The probe is then moved slowly over the area.<\/p>\n
During renal Doppler scanning, images composed of red and blue colors appear on the screen. These colors indicate the speed and direction of blood flow in the vessels.<\/p>\n
Patients scheduled for ultrasound typically undergo a preliminary examination. If the doctor deems it appropriate, the renal Doppler procedure is performed. This method is usually requested for patients with hypertension. Rarely, narrowing in the renal arteries may be caused by hypertension, which is why this imaging technique is often requested for hypertensive patients.<\/p>\n
Renal Doppler criteria for diagnosing renal artery stenosis (RAS) are classified into two groups: proximal criteria (direct evaluation of stenosis at the site) and distal criteria (flow changes observed in renal vasculature distal to the stenosis).<\/p>\n
**Proximal Criteria (Direct Evaluation of Stenosis)**:
\nProximal criteria are direct indicators obtained at the site of stenosis. Four criteria are used to diagnose significant proximal narrowing or occlusion of the renal artery:
\n– The first and most important sign is an increase in PSV. Velocities over 180 cm\/s suggest stenosis of greater than 60%. An end-diastolic velocity greater than 150 cm\/s indicates stenosis of more than 80%.
\n– The second criterion is the renal\/aortic ratio (RAR), which compares the PSV values in the renal arteries with those obtained in the prerenal abdominal aorta. Normally, the RAR is less than 3.5. If the PSV in the prerenal abdominal aorta is abnormally low (less than 40 cm\/s), the RAR cannot be used.
\n– The third criterion is the identification of renal arteries with no detectable Doppler signal, indicating occlusion.
\n– The fourth criterion is the presence of color artifacts in the Doppler evaluation, indicating turbulence in the stenosis region.<\/p>\n
Stenosis greater than 60% is considered significant, as it causes a substantial reduction in renal blood flow.<\/p>\n
**Distal Criteria (Indirect Evaluation of Stenosis)**:
\nDoppler US criteria assess the flow distal to the stenosis (in more accessible arterial segments such as the hilar or interlobar arteries). The concept here is that a hemodynamically significant stenosis should attenuate flow in the renal hilum distal to the stenosis, showing a slow rise in peak systole. This phenomenon is known as the “tardus-parvus” effect, where \u201ctardus\u201d refers to a slow rise to the systolic peak, and \u201cparvus\u201d indicates a low peak systolic height. However, while this finding can assist in diagnosis, its absence does not rule out renal artery stenosis.<\/p>\n
Hypertension affects about 25-30% of the adult population, and its prevalence is expected to rise. It is considered a major risk factor for developing kidney failure and cardiovascular disease. Approximately 80% of patients with chronic kidney disease (CKD) are hypertensive. Renal hypertension or renovascular hypertension refers to hypertension due to renal artery stenosis and kidney disease. Therefore, newly diagnosed hypertensive patients should be screened for underlying kidney disease.<\/p>\n
Renal Doppler ultrasound is widely used for diagnosing, prognosing, and managing kidney diseases. It is a non-invasive, cost-effective, and safe method for evaluating renal blood flow.<\/p>\n
Renal Doppler prices vary by region and even between institutions in the same area within Istanbul. For information on Renal Doppler prices, you can call 02126321059.<\/p>\n","protected":false},"excerpt":{"rendered":"
What is Renal Doppler? Renovascular disease, most commonly caused by fibromuscular dysplasia and atherosclerotic disease, manifests in one of three forms: asymptomatic renal artery stenosis (RAS), renovascular hypertension, and ischemic nephropathy. The atherosclerotic form is especially a progressive condition that can lead to gradual and silent loss of kidney function, making early diagnosis of RAS […]<\/p>\n","protected":false},"author":1,"featured_media":3817,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[6],"tags":[],"class_list":["post-1007","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-color-doppler-ultrasonography-cdus"],"_links":{"self":[{"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/posts\/1007","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/comments?post=1007"}],"version-history":[{"count":4,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/posts\/1007\/revisions"}],"predecessor-version":[{"id":4030,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/posts\/1007\/revisions\/4030"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/media\/3817"}],"wp:attachment":[{"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/media?parent=1007"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/categories?post=1007"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hekimoglugoruntuleme.com\/en\/wp-json\/wp\/v2\/tags?post=1007"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}