The Valsalva: Squeeze, Please (A Sonographer’s Guide to a Gloriously Useful Strain)
The Valsalva: Squeeze, Please (A Sonographer’s Guide to a Gloriously Useful Strain)
Short version: it’s not a gym move, it’s physiology on command. The Valsalva maneuver lets us tweak preload and pressure so hidden findings step into the spotlight. Do it right, and your Dopplers sing, your gradients unmask, and your diagnosis gets crisp.
Why we do it
- Change the loading conditions to see how murmurs, gradients, and valves behave when venous return dips.
- Provoke/right-size flow patterns for venous reflux testing.
- Flip the pressure gradient across the atria to catch a shunt on contrast (bubble) echo.
- Interrogate autonomic function (in the right clinical setting).
- Occasionally, it’s used as a vagal maneuver for certain tachyarrhythmias (that’s a physician play—don’t try to cardiovert with charisma).
What actually happens (the 4 phases without the headache)
Think “forced exhale against a closed glottis” → intrathoracic pressure ↑ → venous return to the heart ↓.
- Phase I (onset of strain): Thoracic pressure spikes → aortic pressure bumps up briefly → tiny HR dip.
- Phase II (continued strain): Venous return and stroke volume drop → BP falls → baroreflex tachycardia kicks in.
- Phase III (release): Pressure suddenly normalizes → brief BP dip.
- Phase IV (overshoot): Venous return rushes back → BP overshoots → reflex bradycardia.
Clinical gold:
- HOCM murmur/gradient: often increases during strain (preload ↓ → obstruction ↑).
- MVP/MR: click/MR can intensify with strain.
- Aortic stenosis murmur: typically softens with strain (less preload).
- Venous reflux: Valsalva in standing helps expose SFJ/SVJ incompetence.
- PFO on bubble study: release phase can push microbubbles RA→LA if a shunt exists.
How to coach a proper, effective Valsalva (that actually works)
The vibe: firm, simple, a bit of swagger. You’re the preload DJ.
General recipe
- Cue: “Deep breath in. Now bear down like you’re trying to blow through a blocked straw—but don’t let any air out.”
- Target effort/time: ≈ 40 mmHg pressure for 10–15 seconds.
- Tools: a 10 mL syringe (try to nudge the plunger), or a disposable mouthpiece/manometer if you’ve got one.
- Timing for bubble study: strain first, then big release/sniff right as the microbubbles hit the RA. Count it down so the camera (and cardiologist) get the money shot.
Positioning tips
- Echo (HOCM/MVP/bubble): typically supine or semi-supine—coach loudly and watch the tracings.
- Venous reflux: standing with weight balanced; hands on the table; warn about lightheadedness.
Common fails (and fixes)
- Cheek-puffers: They’re blowing, not bearing down. Hand on epigastrium helps you feel real strain.
- Air leaks: Use a mouthpiece or nose clip if needed.
- Too short/too weak: Count out loud; show a 10–15 s timer.
- For bubble study: the release is the star—no release, no shunt.
How it helps diagnosis (greatest hits)
- HOCM: amplifies dynamic LVOT obstruction → higher gradients on CW Doppler.
- MVP/MR: earlier click, more MR with reduced LV size.
- AS vs HOCM: AS murmur usually quiets; HOCM loudens—handy bedside A/B.
- PFO/ASD (bubble): catch right-to-left passage during release.
- Venous insufficiency: reproducible reflux at junctions without manual augmentation.
The Valsalva isn’t drama for drama’s sake—it’s physics on tap. Master the coaching, nail the timing, and watch tricky hemodynamics confess. Your gradients get bolder, your bubbles get braver, and your reports get so good it hertz.
-Lara Williams, BS, ACS, RCCS, RDCS, RVT, RDMS, FASE
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