Valvular Disease & TAVR Planning
- Heart valves are one-way doors. They fail two ways: stenosis (the door won't open all the way) and regurgitation (the door won't close all the way and leaks backward).
- Echocardiography (ultrasound) is the workhorse for grading valve disease; CT and MRI step in when echo can't answer the question or a procedure is being planned.
- For TAVR — a catheter-delivered replacement aortic valve — a contrast CT (a "TAVR CT") is the planning study, and it lives or dies on a few precise measurements.
- The whole point of imaging is to answer three questions: which valve, how broken, and what's the plan — replace it, fix it, or watch it.
Think of a heart valve as a saloon door that's only supposed to swing one way. When everything works, blood walks through, the door slaps shut behind it, and nothing sneaks back in. Valvular disease is what happens when that door either gets stuck half-closed or stops sealing. Neither is good, and imaging is how we figure out which kind of broken we're dealing with.
Two ways a door fails
Every valve problem is some flavor of two failures, and it helps to keep them dead simple:
- Stenosis — the door is stiff and won't open fully. The heart has to shove harder to push blood through a narrowed opening, so it builds up pressure and, over time, muscle (a thickened, overworked wall).
- Regurgitation — the door won't close, so blood leaks backward with every beat. The chamber behind it gets stuck pumping the same blood twice, so it stretches and dilates to handle the extra volume.
A quick memory hook: stenosis is a pressure problem (the wall gets thick), regurgitation is a volume problem (the chamber gets big). That single distinction explains most of what you'll see downstream on imaging.
The aortic and mitral valves on the left side take most of the abuse, because the left heart runs at high pressure. The most common villain in older adults is calcific aortic stenosis — decades of wear-and-tear leave the aortic valve crusted with calcium until it barely opens, like a hinge packed with rust.
How we actually image valves
Echocardiography — heart ultrasound — is the front-line test and usually the only one needed. It's live, radiation-free, and Doppler lets us literally watch and measure blood squirting through a narrowed valve or leaking backward. When echo gives a clear answer, we stop there.
But ultrasound has blind spots. A heavily calcified or scarred chest, an awkward body habitus, or a borderline measurement can leave the picture ambiguous. That's when the heavy machinery rolls in.
| Modality | What it's great at | When you reach for it |
|---|---|---|
| Echo (ultrasound) | Live grading of stenosis/regurgitation; gradients across the valve | First-line for nearly everything |
| Cardiac MRI | Quantifying regurgitation; measuring chamber volumes precisely | When echo is equivocal, or you need exact numbers |
| Cardiac CT | Calcium, anatomy, and millimeter-precise measurements | TAVR planning; assessing valve calcification |
If you want the deeper logic of what each MRI sequence is actually telling you, that's its own rabbit hole over in cardiac MRI technique. And the same scanner and contrast timing used here build on coronary CTA.
TAVR: replacing a valve without opening the chest
Here's where radiology gets to show off. TAVR stands for transcatheter aortic valve replacement: instead of cracking the chest open, a cardiologist threads a collapsed replacement valve up through an artery (usually in the groin) and pops it open right inside the diseased aortic valve, like deploying a tiny spring-loaded umbrella. The old valve gets squashed against the wall and the new one takes over.
For that to work, you need a map — and that map is a contrast-enhanced CT of the heart and the whole arterial route down to the groin. The CT answers the questions that decide whether TAVR is even feasible and what size device to use.
A TAVR CT isn't just a picture of the valve. It scans the aortic root and traces the entire path the catheter has to travel — the aorta and the iliac/femoral arteries — to make sure the delivery system can physically get there.
The measurements that matter cluster around the aortic annulus — the ring the new valve seats into. Because that ring is oval, not round, it's measured on a precise plane, and getting it right is everything: too small a device leaks around the edges, too large and you risk splitting or injuring the root. The CT also flags how much calcium is caked on the valve, where the coronary arteries take off (you don't want the new valve to block them), and whether those groin arteries are wide and clean enough to pass the equipment.
The annulus is elliptical, so a single diameter lies to you. Measure it on the proper double-oblique plane, at the right point in the cardiac cycle — eyeballing it on a random axial slice is how a device gets mis-sized. When in doubt, defer to the dedicated annular plane.
Don't tunnel-vision on the valve. On a TAVR CT, the iliac and femoral arteries are part of the read — a tortuous, narrow, or heavily calcified access route can rule out the standard approach and send the team looking for a different entry point entirely.
Putting it together
Valvular disease really does boil down to a stuck door or a leaky one, and most of the imaging effort goes into grading how stuck or how leaky, then deciding whether to intervene. Knowing the normal cardiac anatomy and imaging planes is the foundation that makes any of these measurements meaningful.
Stenosis is a pressure problem (thick walls); regurgitation is a volume problem (big chambers). Echo grades it, and when a TAVR is on the table, the CT's annular measurements and access-route check are what make the procedure possible.