Aortic Valve Stenosis
Aortic valve stenosis is defined as a narrowing in the aortic valve, which restricts maximal opening of the valve, reducing the volume of blood that the aorta is able to pump through systemic circulation. There are a few possible causes of aortic valve stenosis such as a birth defect, calcification, or rheumatic fever, which all can range from mild to severe.1 Aortic valve stenosis can play a large impact on a patient’s life if it becomes severe and goes untreated.
Aortic valve stenosis can occur in a patient valve from a few different causes. In the majority of cases, aortic valve stenosis comes from congenital defects. Congenital bicuspid aortic valves account for 60% of the cases in individuals who are younger than 70 years old whom require surgery and 40% of the patients who are older than 70. Bicuspid Aortic valves related to stenosis is present in 1-2% of the population in the United States.1 Patients’ aortic valves can also become stiff and narrowed due to calcium deposits on the valve. This type valve stenosis typically occurs in aging. The calcium present in our blood is constantly flowing over the valve, causing calcification deposits to develop. Recent research suggests that there may be a genetic component linking calcific aortic valve stenosis coming from an autosomal dominant inheritance.1 Rheumatic fever also a possible way for a patient to get aortic valve stenosis. Rheumatic fever is typically brought upon by an untreated case of strep throat, but these cases are not commonly seen in the United States, rather in underdeveloped countries.2,4
Aortic valve stenosis can be diagnosed a few different ways. A physician is able to hear heart murmurs or other abnormal heart sounds which will typically have a physician order an electrocardiogram, or echocardiogram. These lead to the finding of aortic stenosis usually.1,2 The echo is used to diagnose the thickening of the aortic valve, while also showing how well the valve is functioning. The final step in determining how severe the stenosis may be, a cardiac catheterization will be ordered. 4
Cases of aortic valve stenosis range from mild to very severe, with a rather wide range of symptoms. According to Barone, the most common symptoms seen really depend on the severity of the disease, but appear as angina, blackouts and difficulty breathing.4 In 2014, the American Heart Association and the American College of Cardiology classified aortic valve stenosis into four different stages, A-D. These stages included the following, patient symptoms, leaflet anatomy, valve hemodynamics, and left ventricle function.2 Patients in stage A present with risk of aortic stenosis with either aortic sclerosis or have a congenital bicuspid valve. Stage A patients are typically asymptomatic with no serious valve obstruction. Patients in stage B will have worsening calcification of the leaflets, causing the valve to become thick with decreased mobility. Patients in B stage, have worsening valve obstruction ranked from mild to moderate. Stage C patients are still asymptomatic but have severe valve obstructions. Once a patient presents in stage D, they are symptomatic with left ventricular dysfunction.2
The more stenosis that appears in the aortic valve, the harder the work has to pump to eject blood into system circulation. With increased stiffness in the valve, the left ventricle tends to become slightly enlarged, which reduces the overall ejection fraction. The end stage of aortic valve stenosis will eventually lead to death due to the obstruction of left ventricular output.1
From the 1-2% of the population who is affected in the united states, nearly 100% of this population require aortic valve replacement eventually in their lifetime.1 The only proven, effective treatment for aortic valve stenosis is replacement.1,4 The main goal of treatment in valve replacements is to enhance patients exercise abilities, improve overall life quality, and to prolong the life expectancy.1 There are two types of surgical procedures to replace the aortic valve, SAVR (surgical aortic valve replacement), or TAVR (transcatheter aortic valve replacement).1,2 Currently, the SAVR is the standard, more common approach. Patients with cases that present to be a higher risk, or inoperable, will use the TAVR.1 With both of these approach’s, the survival rate and length is high, and once completed the patient’s life expectancy is comparable to someone whom is in the similar age range without aortic valve stenosis.2
There are two different types of valves used in SAVR and TAVR procedures, bioprosthetic valves or mechanical valve.1 A bioprosthetic valve uses a pig valve typically, or in some cases, will use the pulmonic valve from the patient and then further replace the pulmonic valve with a mechanical one. There is another option beside replacement for a temporary fix, this involves a balloon catheter to assit the valve in opening.4 Major considerations when looking at which type of valve may be used are the risks of reoperation with bioprosthetic valves, or the risks associated with anticoagulants, such as warfarin when a mechanical valve is used.2 Patient age and medical status play a role in selecting which type of valve they receive. Patients who are 60 years and younger, typically receive a mechanical valve if they present with no contraindications to anticoagulants. Patients who are older than 60-70 years of age, bioprosthesis valves are preferred since the anticoagulation risks are avoided, but the patience preference also plays a factor.2
In the most recent research, there is no evidence that medical therapies can slow or stop the progression of aortic valve stenosis.1,2,3 As for pharmacological treatments, patients who have aortic valve stenosis must take antibiotics such as amoxicillin, erythromycin, or clindamycin, before dental work and surgeries, and some other surgical procedures.4 Taking these medications reduces the risk of infection in the aorta and aortic valve. The best treatment, is to regularly evaluate the condition, and treat any concurrent issues, while measuring the severity of the stenosis.2 In relation to physical therapy, there is a gap in the research, but exercise with aortic stenosis can be beneficial to some patients, and harmful to others. When patients are classified as mild to moderate, they are put on restrictions from high cardiovascular exercise and heavy weight training.3,5 Asymptomatic, congenital patients are encouraged to exercise and stay in good cardiovascular shape to keep the heart healthy.
Aortic valve stenosis, although is said to be degenerative, patients can be asymptomatic for a long time before it becomes a critical issue.3 Someone diagnosed with congenital aortic valve stenosis, typically lives a normal life without any restrictions until the valve becomes severely stenosis.
Reference Page
1. Otto CM, Prendergast B. Aortic-valve stenosis — from patients at risk to severe valve obstruction. N Engl J Med. 2014;371(8):744-56.
2. Rashedi N, Otto CM. Aortic stenosis: changing disease concepts. Journal of Cardiovascular Ultrasound. 2015;23(2):59-69. doi:10.4250/jcu.2015.23.2.59.
3. Freeman RV. Spectrum of calcific aortic valve disease: pathogenesis, disease progression, and treatment strategies. Circulation, Contemporary Views in Cardiovascular Medicine. 2005, 111 (24): 3316-3326.
4. Barone, Jeanine. "Aortic valve stenosis." In The Gale Encyclopedia of Medicine, 5th ed., edited by Jacqueline L. Longe. Farmington Hills, MI: Gale, 2015. Health & Wellness Resource Center
5. Davidson T, Cataldo L. Aortic Valve Stenosis. The Gale Encyclopedia of Senior Health: A Guide for Seniors and Their Caregivers. 2015;1:236-240.