Download Cardio113-ValsalvaManeuver

Cardio #113
Mon 02/10/03
Dr. Smith
Troy Phillips
Valsalva Maneuver
I.
Valsalva Maneuver
a. Performed by closing the glottis (or using a closed mouthpiece) and then
trying to force air out (for at least 10 seconds) causing intrathoracic
pressure to rise.
b. Used clinically to assess central hemodynamic function, arterial baroreflex
function and valve function.
c. Phases are dictated by changes in blood pressure which “better be the
same” as left ventricular pressure.
II.
4 phases (in healthy patient)
a. Phase 1
1. Brief increase in arterial pressure due to compression of
ventricles, aorta and large arteries.
2. Causes brief increase in stroke volume, BP and cardiac work
with no change in HR.
b. Phase 2
1. Marked by sharp decrease in blood pressure (may plateau)
2. Elevated intrathoracic pressure tends to collapse vena cava
where they enter thoracic cavity causing significant decrease in
venous return which then leads to a decrease in preload, SV, CO,
and arterial pressure. All of this in turn leads to a baroreflex
mediated increase in HR
c. Phase 3
1. Marked by stopping maneuver which relieves intrathoracic
pressure.
2. Reverse of events of stage 1.
3. Left side has drop in output while right side has an increase in
output due to increase venous return.
4. Venous return and cardiac output are mismatched for a couple of
heartbeats.
d. Phase 4
1. Increase in venous return which leads to increase in preload, SV,
CO, and BP. All of this in turn leads to baroreflex mediated
decrease in HR.
2. Occurs within 1-6 heart beats.
Exam Question: Is a β1 adrenergic blocker going to affect heart rate during phase 2? No,
there is no sympathetic control in phase 2, only parasympathetic.
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Cardio #113
Mon 02/10/03
Dr. Smith
Troy Phillips
During Each Phase
Venous return
Preload
Stroke volume
Cardiac output
Velocity of shortening
Heart rate
Sympathetic NA
Parasympathetic NA
Blood Pressure
III.
IV.
1
↓↓
↓
↑ (init.) ↓
↑ (init.) ↓
↓
↓ (slight)
↓
↑
↑
2
↓
↓
↓
↓
↑
↑
↓
↓
3
↑
↑
↓
↓
↑
↑
↑
↓
↓
4
↑
↑
↑
↑
↓
↓
↓
↑
↑
Uses of the Valsalva Maneuver
a. Assess hemodynamic function
1. Main focus is on BP response
2. Effect of graded Valsalva straining
3. Supine vs. upright
i.
supine resembles heart failure due to increased volume
around heart
ii.
astronauts (weightlessness) resemble supine position due to
“headward shift” of blood volume
b. Assess baroreflex function
1. Focus is phase II and IV
2. Relative HR response to BP response
i.
as blood pressure increases, heart rate should decrease
(baroreceptor control, lacking in heart failure)
3. DBP response to phase IV gives an indication of the vasopressor
response.
c. Assess valve function
1. Many murmurs are reduced due to decreased stroke volume and
cardiac output.
i.
Take home question: Which phases would you expect to
see decreased murmurs?
2. Phase IV can help distinguish right heart murmurs from left heart
murmurs
i.
very transient
Valsalva Maneuver in CHF
a. Resembles Valsalva maneuver performed while supine
1. due to increased fluid volume around heart
b. Phases II and IV are unclear
1. “Square wave” response
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Cardio #113
Mon 02/10/03
Dr. Smith
Troy Phillips
c. Diuretics should improve Valsalva maneuver results in CHF
1. Diuretics act to reduce fluid around heart
*Review diagrams in power points of normal Valsalva vs. CHF
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