AVS is a medical abbreviation with several meanings depending on the context. The most common uses are adrenal venous sampling (a diagnostic procedure), aortic valve stenosis (a heart condition), acute vestibular syndrome (a neurological presentation), and after-visit summary (a patient document). Which meaning applies depends entirely on the medical setting where you encountered it.
Adrenal Venous Sampling
Adrenal venous sampling is a minimally invasive procedure used to pinpoint which adrenal gland is overproducing the hormone aldosterone. Your two adrenal glands sit on top of your kidneys and help regulate blood pressure. When one or both glands make too much aldosterone, a condition called primary aldosteronism, your blood pressure rises and your potassium drops. First described in 1967, AVS remains the key diagnostic step for patients considering surgery for this condition.
The core question AVS answers is whether the excess aldosterone is coming from one gland or both. This matters because the treatments are completely different. If one gland is the culprit (usually because of a small benign tumor), surgically removing it can cure the problem. If both glands are overproducing, surgery won’t help, and lifelong medication is the better path. Imaging alone, like a CT scan, often can’t make this distinction reliably, which is why AVS exists.
During the procedure, an interventional radiologist threads a thin catheter through a vein in the groin up to the small veins draining each adrenal gland. Blood samples are drawn from both sides and compared. The lab measures aldosterone and cortisol levels from each gland, then calculates a ratio. A cortisol-corrected aldosterone ratio greater than 4-to-1 from one side compared to the other indicates that side is producing the excess. The procedure typically takes one to two hours, and most people go home the same day.
Aortic Valve Stenosis
Aortic valve stenosis is a narrowing of the aortic valve, the gateway between your heart’s main pumping chamber and the large artery that delivers blood to the rest of your body. When this valve stiffens and narrows, usually from calcium buildup over decades, the heart has to work harder to push blood through. About 5% of people have some degree of aortic stenosis by age 65, and the prevalence climbs with age. Among people 75 and older, 3.4% have severe aortic stenosis in both Europe and the United States.
Doctors classify severity using echocardiography (an ultrasound of the heart) and look at three main measurements: how fast blood jets through the narrowed valve, the pressure difference across it, and the remaining opening area. Severe aortic stenosis is defined as a peak jet velocity above 4.0 meters per second, a mean pressure gradient above 40 mmHg, and a valve opening smaller than 1.0 square centimeter. A healthy aortic valve opens to about 3 to 4 square centimeters, so severe stenosis means the opening has shrunk by roughly two-thirds or more.
Mild aortic stenosis may cause no symptoms for years. As it progresses, people typically notice shortness of breath during activity, chest tightness, dizziness, or fainting. Once symptoms appear with severe stenosis, the outlook without treatment worsens significantly. Treatment for severe symptomatic cases involves replacing the valve, either through open-heart surgery or a catheter-based procedure where a new valve is threaded through a blood vessel and expanded inside the old one.
Acute Vestibular Syndrome
Acute vestibular syndrome describes a sudden episode of continuous vertigo lasting longer than 24 hours, typically accompanied by nausea, vomiting, and intense sensitivity to head movement. It is not a single disease but a clinical presentation. The two most important causes to distinguish are a benign inner ear inflammation (vestibular neuritis) and a stroke in the back of the brain. Both can look remarkably similar, which is what makes AVS diagnostically challenging.
Emergency physicians use a bedside exam called HINTS to help tell these apart. The acronym stands for Head Impulse, Nystagmus direction, and Test of Skew. Each component checks a different aspect of how the eyes and balance system respond. When all three tests point toward a benign cause, the combination has been shown to be 100% sensitive and 96% specific for ruling out stroke, outperforming even an MRI done within the first 48 hours of symptoms. This makes HINTS one of the most powerful bedside exams in emergency neurology.
After-Visit Summary
In outpatient clinics and hospitals, AVS frequently refers to the after-visit summary, a document you receive at the end of a medical appointment. These summaries consolidate your diagnoses, treatment plan, follow-up instructions, and current medications into one reference sheet, provided either on paper or through an online patient portal.
Research on how patients use these documents shows that about 83% of people recall receiving one, and roughly 67% actually read it afterward. Nearly half consult it more than once, and about a third share it with a family member or caregiver. Patients consistently rate test results and treatment plan instructions as the most helpful sections. One common source of confusion is medication lists that show started, stopped, and modified drugs separately. Both patients and doctors tend to prefer a single “current medications” list instead.
Personalized after-visit summaries that include graphs, lab trends, and plain-language explanations of diagnoses are better received than generic printouts. If you’re unsure what something on your AVS means, it’s worth flagging it at your next appointment, since the document is meant to be a practical reference between visits, not just a receipt.
Less Common Uses of AVS
In pediatric cardiology, AVS can occasionally appear as shorthand related to atrioventricular septal defect (more commonly abbreviated AVSD). This is a congenital heart defect where there are holes between the chambers of the heart along with abnormalities in the valves that separate them. A complete form involves openings between both the upper and lower chambers, while a partial form affects only the upper chambers with a cleft in one of the heart valves. Surgical repair for the complete form is generally done within the first six months of life, while partial defects are typically repaired between ages 4 and 5.
Context almost always makes the intended meaning clear. If you see AVS on a cardiology report, it likely refers to aortic valve stenosis. On an endocrinology order, it points to adrenal venous sampling. On a patient handout from your clinic, it’s your after-visit summary.