What is Aortic Stenosis (Aortic Valve Stenosis)?
Aortic stenosis is a common heart valve disorder that blocks the flow from the left part of the heart. To note, the forward speed across the valve needs to be at least 2 m/sec. On the other hand, ‘aortic valve sclerosis’ is a condition where the heart valve becomes thick and hard without creating significant pressure. The causes can be inherited conditions, calcification, and diseases caused by abnormal immune response.
Symptoms like shortness of breath or fatigue during exercise slowly appear after an extended no-symptom period of around 10 to 20 years. Afterwards, patients may experience chest pain, heart failure, and fainting spells. Aortic stenosis is typically treated through aortic valve replacement, which can be done surgically or through a less invasive method. If untreated, the survival rate is high during the period when there are no symptoms, but the death rate becomes more than 90% within a few years after symptoms start to appear.
What Causes Aortic Stenosis (Aortic Valve Stenosis)?
Aortic stenosis, or a narrowing of the aortic valve, can be caused by both inborn (congenital) and developed (acquired) factors. If a person is born with an abnormal valve that later becomes hardened or calcified, it can result in aortic stenosis. The most common cause in people under 70 in developed countries is a condition called bicuspid aortic valve.
On the other hand, a disease known as rheumatic valve disease is the most common culprit behind aortic stenosis in developing countries. With this illness, the tiny hinges on the valve’s flaps stick to each other, leaving only a small hole for blood to flow through. Other factors can include calcification of the three-flap valve, various metabolic diseases, and conditions like alkaptonuria, systemic lupus erythematosus, and dosonosis.
Certain metabolic disturbances like end-stage kidney disease can also result in hardening of the valve. Added to that, obstruction can happen either above or below the valve, causing what’s known as supravalvular and subvalvular stenosis, respectively. A disease called hypertrophic cardiomyopathy can also lead to dynamic subvalvular stenosis, which is a less common cause of this kind of obstruction.
Risk Factors and Frequency for Aortic Stenosis (Aortic Valve Stenosis)
Calcific aortic sclerosis is a condition that becomes more common as people get older. Among people aged 65 or less, around 1% to 2% have it. But in patients aged 65 or older, the rate jumps to 29%. Furthermore, between 2 and 9% of those over 75 years old have serious aortic stenosis.
The presence of aortic sclerosis can range from 9 to 45% in people with an average age of 54 to 81, and this also increases with age. The rate of aortic stenosis can change based on whether patients have normal or abnormally formed valves and this is impacted by their age.
The causes for aortic stenosis can also differ depending on where you live. For instance, calcific stenosis is more common in North America and Europe, while a type of heart disease called rheumatic valve disease is more prevalent in developing countries. As the general population continues to age, the numbers of these conditions are estimated to double or even triple in the next few decades.
Signs and Symptoms of Aortic Stenosis (Aortic Valve Stenosis)
Acquired aortic stenosis is a condition that can result in symptoms like shortness of breath during exercise, fainting, chest pain, and ultimately, heart failure. Usually, these symptoms begin to appear in patients between 50 and 70 years old with a particular type of heart valve condition known as bicuspid aortic valve. For patients above 70 with another type of condition called tri-leaflet valve calcific stenosis, similar symptoms occur.
As these conditions progress, patients often experience a gradual decline in their ability to exercise, have difficulty breathing after exertion, and begin to feel generally worn out.
Severe symptoms, such as difficulty breathing during exercise, waking up suddenly due to difficulty breathing, difficulty breathing while lying down, and fluid build-up in the lungs, are indications of a severe level of this hypertension. Chest pain, which results from increased oxygen demand in the heart muscle and reduced oxygen supply due to squeezed heart vessels, is another possible sign.
- Shortness of breath during exercise
- Fainting
- Chest pain
- Heart failure
- Difficulty breathing after exertion
- Fatigue
Fainting can happen when blood flow to brain lessens during physical activity because the large arteries of the body expand, and the heart isn’t able to pump out enough blood due to the stenosis. Also, the normal body mechanism of controlling blood pressure doesn’t function properly in severe cases of aortic stenosis.
Non-cardiac symptoms may include gastrointestinal bleeding and formation of clots in the brain. Patients with severe aortic stenosis are also exposed to a higher risk of infective endocarditis, especially if they have a bicuspid valve. Other noticeable signs of aortic stenosis include a forceful thrusting sensation when the neck’s carotid arteries are felt and specific changes in heart sounds and murmurs heard during a physical check-up.
Testing for Aortic Stenosis (Aortic Valve Stenosis)
Echocardiography, a type of ultrasound that shows how your heart’s chambers and valves are functioning, is the usual method to check on and monitor patients with aortic stenosis, a condition where the heart’s aortic valve narrows. This can also guide doctors on when to do surgery. It provides a view of the valve’s structure, the extent of valve hardening or ‘calcification’, and allows for a direct visual of the valve opening or ‘orifice area’.
A more insightful method of predicting severe events including death due to heart issues is via longitudinal systolic strain imaging. This is a way to measure the change in the heart’s length during the contraction phase of the heartbeat.
Exercise testing may be done to uncover symptoms in those who do not show any signs. However, for those who already have symptoms, this test should be avoided.
Cardiac computed tomography (CT), which takes detailed pictures of the heart, is becoming more common for patients with a condition where the aortic valve hardens, or calcifies. This is usually done when other non-invasive tests do not provide clear results.
Cardiac magnetic resonance imaging (MRI), a scanning technique that gives detailed images of the heart, can be used to measure the heart’s size, its pumping ability, and volume when an echocardiography cannot readily provide these pieces of information.
Treatment Options for Aortic Stenosis (Aortic Valve Stenosis)
Research has demonstrated that medical treatment doesn’t significantly slow down the progression of aortic stenosis, a disease affecting the heart’s aortic valve. Consequently, aortic valve replacement (AVR), an operation where a damaged aortic valve is replaced, is seen as the superior treatment for severe forms of this disease, based on observational studies and controlled trials.
Some patients may also have high blood pressure, and treating this condition can be a concern because aortic stenosis presents a unique challenge. But, research has shown that even among these patients, measures to dilate blood vessels can lead to an increase in the volume of blood pumped in each heartbeat. Angiotensin-converting enzyme inhibitors and angiotensin receptor blockers are often the preferred choices for these patients.
AVR is recommended for patients with heart failure and volume overload, but medications like diuretics can help decrease fluid buildup and relieve symptoms ahead of the operation. While balloon aortic valvuloplasty, a nonsurgical procedure to widen the aortic valve, can momentarily improve the patients’ condition and briefly enhance survival and quality of life, these benefits are not sustained in the long term.
AVR is also recommended for adults with aortic stenosis showing symptoms, even if these are mild. It’s also advised for asymptomatic patients with severe aortic stenosis under certain conditions, such as lesser heart function, upcoming heart surgery, abnormal treadmill test results, excessively high peak velocity and pressure gradient, and rapid progression of peak velocity annually. AVR can be carried out surgically or through a nonsurgical method called transcatheter AVR.
Post-surgery, most patients see relief in symptoms like difficulty in breathing and chest pain during physical activity, and they generally have improved exercise tolerance. Heart function often improves after surgery, albeit with some lingering effects. The risk of dying during the AVR procedure is about 3.2% for surgical approach, falling to under 1% for younger patients with minimal other health issues. Advanced age shouldn’t deter patients from surgery, as the 30-day mortality rate is about 4.2%.
In the non-surgical (transcatheter) approach to AVR, the way calcific aortic stenosis is treated has been completely transformed. Initially, it proved to be superior to medical therapy in patients who aren’t suitable for surgery. But subsequently, it has been found to be superior even to surgical AVR in high-risk and intermediate-risk patients. The long-term effectiveness of this procedure is yet to be established. The transfemoral approach, carried out through the femoral artery in the thigh, is most commonly used.
To decide whether surgical AVR or transcatheter AVR is the right way forward, a team consisting of heart specialists, valve disease imaging experts, nurses, anesthesiologists, and geriatricians is essential due to the complexities involved. Guidelines on when and in what circumstances to consider AVR for aortic stenosis patients are available, depending on the stage of the condition and other factors.
What else can Aortic Stenosis (Aortic Valve Stenosis) be?
Many symptoms, like fainting (syncope) and chest pain (angina), are common to many different diseases, which can make diagnosing a specific condition difficult in immediate care situations. Issues like heart muscle disease (cardiomyopathy) and blocked heart arteries (coronary artery disease) often contribute to these symptoms.
Difficulty breathing during exercise (exertional dyspnea) can also be caused by non-heart related conditions like lung disease. Diagnosing these issues can be tough, but tests that measure lung function and heart and lung performance during exercise can help distinguish between different conditions.
There can be other reasons for a specific kind of heart murmur that happens when the heart is contracting and pushing out blood (ejection systolic murmur), with or without blockage in the left ventricle’s output. These reasons can include thickening of the heart muscle (hypertrophic cardiomyopathy), hardening of the aortic valve (aortic sclerosis), and narrowing below the valve (subvalvular stenosis). This narrowing can be caused by various permanent changes and can also have a dynamic component.
A high number of cases where the narrowing occurs above the valve (supravalvular stenosis) take place in people with Williams syndrome. Most patients have a narrowing that looks like an hourglass, with a tight squeeze on a thickened part of the aorta, right above the sinus of Valsalva, a part of the heart chamber connected to the aorta.
What to expect with Aortic Stenosis (Aortic Valve Stenosis)
In patients who show no symptoms, doctors usually repeat imaging tests every 3 to 5 years for mild aortic stenosis, every 1 to 2 years for moderate stenosis, and every 6 to 12 months for severe stenosis unless symptoms start to appear. The progression rate for aortic stenosis is hard to predict because it varies greatly. Factors like old age, severe leaflet calcification, high blood pressure, obesity, smoking, high lipid levels, kidney problems, metabolic syndrome, and increased activity of a specific type of protein can cause the condition to worsen quickly.
The most accurate predictor of symptom progression in patients without symptoms is the speed of blood flow through the aorta.
Patients with moderate to severe aortic stenosis who don’t have symptoms generally have a great prognosis. However, certain factors can help doctors predict the onset of symptoms and survival without symptoms in these patients. They include low heart contractibility, low blood flow, high levels of a heart-related protein (BNP), frailty, chronic lung disease requiring oxygen, severe kidney dysfunction, and high surgical risk scores.
When the severity of the stenosis is moderate or symptoms are uncertain, a high BNP level can be helpful, but its role in the disease progression is not entirely understood. Symptomatic patients, even with mild symptoms, generally have a poor survival rate unless the blockage in the outflow of the heart is relieved. On average, survival without heart valve replacement surgery after symptoms appear is only about 1 to 3 years.
Possible Complications When Diagnosed with Aortic Stenosis (Aortic Valve Stenosis)
People with severe aortic stenosis symptoms are more likely to experience sudden death, so it’s important that they receive a treatment called AVR as soon as possible. While this sudden death risk is particularly high for those showing symptoms, it can also happen occasionally to people without symptoms.
Heart failure is often associated with aortic stenosis. Most of those affected will have an enlarged left ventricle in their heart, but with normal pumping capacity. They might develop a condition known as diastolic dysfunction due to this enlargement and scar tissue, and this might continue even after undergoing AVR. But some people might show signs of systolic dysfunction, where the heart can’t pump effectively due to an excessive load, resulting in low ejection fraction.
Pulmonary hypertension, which is high blood pressure in the lungs, can occur due to long-term high filling pressure in the left ventricle. Aortic stenosis can also lead to problems with the heart’s electrical signals due to heart enlargement, extension of calcium from the valve to the wall that separates the ventricles, or other underlying heart conditions.
Aortic stenosis patients also carry additional risks, such as:
- Infective endocarditis, especially in patients with a two-flap aortic valve.
- Increased likelihood of bleeding—particularly gastrointestinal bleeding—an outcome of Acquired von Willebrand Syndrome.
- Potential occurrence of cerebral or complete body emboli, caused by calcium debris from the valve.
Preventing Aortic Stenosis (Aortic Valve Stenosis)
There’s a need to create and use effective methods of education after an operation. It’s crucial to monitor the outcome of these strategies, and adjust the instruction given to patients as necessary. It’s also very important to understand which patient attributes might lead to poor results. Doctors and nurses play a critical role in this patient education.
It’s especially important to educate patients who don’t yet have symptoms about what to watch for, so they can seek out early treatment. The use of tailored educational content, digital platforms to distribute information, personalized tutoring, and improvement of teaching tactics in various settings have shown great success. Patients should have a clear understanding of both the benefits and drawbacks of each procedure to make an informed decision.
Patients also need to know how to change their wound dressings and recognize signs of infection after heart valve surgery. They should know when it’s necessary to alert their doctor or nurse about certain symptoms. Women who wish to conceive and athletes must be informed about how to adjust their physical activity and treat their condition before getting pregnant respectively. Additionally, clear information about diet, medicines and physical exercise guidelines should be shared to achieve the best results.
