Aortic stenosis: Clinical sciences

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Introduction0:00–0:31

Aortic stenosis is a type of valvular heart disease that occurs when the aortic valve narrows and prevents blood from flowing normally.
Because the heart has to pump harder through a narrowed aortic opening there is a chronic pressure overload, which leads to left ventricular hypertrophy, reduced stroke volume, and left ventricular dysfunction.
Symptoms involve the classic triad of chest pain, syncope, and heart failure. Alright, if a patient presents with a chief concern suggestive of aortic stenosis, you should first perform an ABCDE assessment to determine if they are stable or unstable.

Unstable0:31–3:45

If the patient is unstable, stabilize the airway, breathing, and circulation. Next, obtain IV access and start IV fluids for resuscitation.
Finally, initiate continuous vital sign monitoring, including pulse oximetry, blood pressure, and heart rate. Your next step is to obtain a focused history and physical exam.
When dealing with unstable patients with aortic stenosis, always think of cardiogenic shock. The patient might report a history of angina, shortness of breath, orthopnea, decreased exercise tolerance, and edema.
In addition, patients may have a history of heart failure or atrial fibrillation. On the other hand, the physical exam might reveal hypotension, tachycardia, and possible arrhythmia.
The skin might appear cold, clammy, and pale due to heart failure. Your most important clue will come from auscultation.
Here, you will notice a loud mid-late peaking systolic murmur in the second right intercostal space. Also, you might find an S4 heart sound due to pressure overload, or lung crackles, indicating edema.
With these findings, suspect aortic stenosis. Okay, the next step is to order an ECG and transthoracic echocardiogram, which is vital in the management of aortic stenosis.
ECG may show an arrhythmia like atrial fibrillation, or left ventricular hypertrophy. On echo, you may find thickened aortic leaflets with or without calcification, reduced systolic motion, a small aortic valve orifice, and a concentrically or uniformly hypertrophied left ventricular wall.
If you see these findings, you are dealing with aortic stenosis. Here’s a clinical pearl!
Transesophageal echo is not performed for these patients, because it requires sedation that can lead to hypotension and cardiac arrest.
Additionally, sedation alters the afterload for the heart, so the severity of valve disease is underestimated. Now that you’ve made the diagnosis, you can proceed with treatment and management.
Unstable patients require urgent surgical consultation for valve replacement. There are two options: surgical aortic valve replacement or SAVR, which is an open heart surgery; or transcatheter aortic valve implantation or TAVI.
TAVI is a transcatheter interventional surgery during which a new aortic valve is placed on a stent through the old aortic valve.
This is only used for aortic stenosis, not aortic regurgitation. If the patient has other cardiac symptoms suggestive of ischemic heart disease, you should proceed with coronary angiography and cardiac catheterization.

Stable3:45–5:30

Alright, now that unstable patients are taken care of, let's go back to ABCDE and talk about stable ones. The next step here is to obtain a focused history and physical exam.
Keep in mind that some of these patients might be asymptomatic. However, symptomatic patients typically report a history of angina, shortness of breath, orthopnea, as well as syncopal episodes, decreased exercise tolerance, or edema.
In addition, patients may have a history of heart failure or atrial fibrillation. On physical exam, you may find hypotension with a possible arrhythmia.
You will also find a low volume, slow rising carotid pulse on neck exam. As before, your most important clue comes from auscultation.
So, you will notice a loud mid-late peaking systolic murmur in the second right intercostal space, and possibly an S4 sound.
Lastly, you might hear lung crackles, which would indicate edema. With this presentation, suspect aortic stenosis.
The next step in the diagnosis is to obtain a transthoracic echocardiogram for further evaluation. On echo, you may find thickened aortic leaflets, with or without calcification or a bicuspid valve, reduced systolic motion, a small aortic orifice, or a concentrically or uniformly hypertrophied left ventricular wall.
These findings confirm the diagnosis of aortic stenosis. It is important to know that echo measures aortic valve area, mean pressure gradient, and maximum velocity across the valve to determine the grade, or severity, of stenosis, which could be mild, moderate, or severe.
Now let's talk about the management. Patients with mild aortic stenosis are typically asymptomatic.

Mild5:30–5:44

They should come back for transthoracic echo every 3-5 years to follow progression or sooner if they develop symptoms. On the other hand, patients with moderate aortic stenosis are also usually asymptomatic.

Moderate5:44–5:56

They should come back for a transthoracic echo every 1-2 years, or sooner if they develop symptoms. Finally, for patients with severe aortic stenosis, the treatment choice depends on their symptoms.

Severe5:56–8:07

Lets first look at asymptomatic patients. First assess the ejection fraction.
If the ejection fraction is greater than 50%, proceed with exercise tolerance testing to see if symptoms develop with exertion or if they are truly asymptomatic.
If they have exertional symptoms and are good surgical candidates, they should get SAVR. However, if they are poor surgical candidates, continue monitoring them to see if they become symptomatic.
On the flip side, patients with ejection fraction less than 50% should undergo valve replacement like SAVR or TAVI. Finally, let's discuss symptomatic patients with severe aortic stenosis.
These patients will need an aortic valve replacement. The team consisting of a cardiologist and cardiac surgeon will determine if they should undergo SAVR or TAVI based on their surgical risk calculation.
Here’s a clinical pearl! Society of Thoracic Surgeons or STS risk calculator is used to calculate the patient's surgical risk score and determine if they should undergo SAVR or TAVI.
And here’s a high-yield fact! There are 2 types of valve that can be used for replacement.
A mechanical valve is a man-made one, while a bioprosthetic or tissue valve refers to tissue from a pig, cow, or horse. TAVIs are tissue valves.
Mechanical valves should last a lifetime but require high-dose warfarin for a lifetime due to the risk of clotting. This, in turn, comes with a risk of bleeding complications.
Tissue valves don't have this risk because they don't need warfarin but they do wear out after 10-15 years. For this reason, mechanical valves are reserved for patients who are under 50 years old so they won't need future open heart surgeries.
Finally, both types have the same risk of future infection with endocarditis, so that isn't a factor in deciding. Alright, as a quick recap… Aortic stenosis is a type of valvular heart disease that occurs when the aortic valve narrows and prevents blood from flowing normally.

Review8:07–8:44

Unstable patients with aortic stenosis should be assessed using transthoracic echocardiogram, and treated with urgent SAVR or TAVI.
If they have other cardiac symptoms, you can proceed with coronary angiography and cardiac catheterization. On the other hand, the treatment for stable patients is based on the stage of the disease and symptoms.
Treatment might involve follow-up evaluation with echo,
Aortic stenosis: Video, Causes, and Symptoms | Osmosis