Cardiac Valve Stenosis

Question 1

As flowing fluid enters a smaller orifice (e.g. a valve), what happens to flow rate and flow velocity?

Answer 1

Flow rate stays the same (it must).
Flow velocity increases, as does pressure…
simple stuff, here

Question 2

How does Bernoulli’s equation and doppler echo help you diagnose mitral stenosis?

Answer 2

By measuring flow velocity you can calculate the pressure gradient.

Question 3

What equation can you use to estimate valve areas? What parameters must you measure?

Answer 3

If you know CO, systolic ejection period (for aortic valve) or diastolic filling period (for mitral valve), and the pressures of the 2 chambers flanking the valve… you can put it into the Gorlin equation get the valve area.

Question 4

If there’s aortic stenosis, what will the Wigger diagram look like?

Answer 4

LV pressure will be wayyy higher than normal, creating a 3-5 mmHg pressure gradient instead of the normally small difference between LV and aorta pressure.

Question 5

What changes happen to the LV with longstanding aortic stenosis?

Answer 5

Concentric LV hypertrophy (it sees increased afterload, so the change is similar to that of hypertension)

Question 6

When there’s stenosis, is there usually high enough flow velocity to create turbulence?

Answer 6

Yep.

Question 7

What’s about the greatest mean systolic pressure gradient that can be generated between LV and aorta?

Answer 7

150 mmHg - beyond that is outside “the rectangle of life.”

Question 8

Is aortic stenosis a slowly or rapidly-developing disease?

Answer 8

Slowly, and the LV adapts up to a point. People are often asymptomatic until things have gotten quite bad.

Question 9

Outcomes of aortic stenosis? (3 things)

Answer 9

Angina pectoris - hypertrophy limits perfusion.
Effort-related syncope or presyncope - CO can’t increase in response to exercise.
Congestive heart failure - decrease in contractility, diastolic compliance

Question 10

What do you do when aortic stenosis becomes symptomatic?

Answer 10

Replace the valve.

Question 11

Is there normally a big pressure gradient between LA and LV during diastole?

Answer 11

Nope.

Question 12

What does mitral stenosis look like on echo?

Answer 12

Restricted mitral leaflet movement.
High velocity flow through mitral orifice.
“Smoke” in LA indicating sluggish flow. (static blood is echogenic)

Question 13

What effect does increasing HR have on mitral stenosis?

Answer 13

Increasing HR worsens the situation: the already struggling diastolic filling period is shorted.

Question 14

How does the heart adapt to mitral stenosis?

Answer 14

It doesn’t.

Question 15

How does the heart/circulation change with chronic mitral stenosis? (problems this creates?)

Answer 15

LA dilates (increased A Fib risk, thrombis risk).
Body tries to increase CO by increase HR, but this makes things worse.
Pulmonary venous HTN (dyspnea) -> pulmonary arterial HTN (pulmonary arteriolar destruction) -> increased RV afterload -> RV hypertrophy.
Right heart failure -> systemic congestion (hepatic dysfunction, edema, and ascites).

Basically everything gets backed up.

Question 16

Once symptomatic, does mitral stenosis have a gradual or rapid course?
Predominant symptoms?

Answer 16

As mitral stenosis becomes symptomatic right away, the symptomatic deterioration is gradual.
Dyspnea on exertion, fatigue from low CO are main symptoms (early on).

Question 17

What are 2 ways in which mitral stenosis deteriorates in a way that won’t be helped by valve replacement?

Answer 17

Severe PA hypertension from obliterative pulmonary arteriolar disease.
RV failure secondary to tricuspid regurgitation.