Leg Pulses and Blood Pressure in Coarctation of the Aorta

1. When should you suspect coarctation of the aorta?

ANS: In any patient with hypertension.

2. What are the characteristics of the pulses proximal to and beyond an aortic coarctation?

ANS: The proximal pulses, i.e., the carotid and brachial pulses, are large, bounding pulses. The parts of the body beyond the coarctation (i.e., usually beyond the left subclavian artery) receive blood through enlarged collaterals that do not transmit the percussion wave well. Therefore, not only do the lower extremity pulses have a low pulse pressure, but also their rate of rise is slow and they have a late peak, i.e., the pulse wave is almost purely a tidal wave.

Note: The blanching time (time required for normal color to return after firm pressure on the foot skin) is normally about 1.3 s in the toes, but averages over 3 s in the presence of coarctation.

3. If the onsets of the femoral and radial pulses are almost simultaneous, what causes the sensation of the delayed peak in the femorals?

ANS: Because of the decreased initial flow rate through the femorals, their percussion wave is so low that only the tidal wave is felt in the femorals.

Anacrotic Shoulder

Onset almost simultaneous

Intra-arterial pressure tracings in a patient with coarctation of the aorta show that the onsets of the femoral and radial pulses remain almost simultaneous. In coarctation, a delay in the femoral is felt on palpating both arteries simultaneously because the percussion wave distal to an obstruction is obliterated by an anacrotic shoulder, which is imperceptible. Thus only the tidal wave is felt in the femoral artery, whereas the earlier percussion wave is felt in the unobstructed radial artery.

Onset almost simultaneous

Intra-arterial pressure tracings in a patient with coarctation of the aorta show that the onsets of the femoral and radial pulses remain almost simultaneous. In coarctation, a delay in the femoral is felt on palpating both arteries simultaneously because the percussion wave distal to an obstruction is obliterated by an anacrotic shoulder, which is imperceptible. Thus only the tidal wave is felt in the femoral artery, whereas the earlier percussion wave is felt in the unobstructed radial artery.

In the radials, the usual percussion wave is easily felt because there is no obstruction to flow.

4. How can you overcome the difficulties in timing and comparing the femoral and radial pulse peaks to look for a femoral delay?

ANS: a. Place the patient's wrist over the femoral artery, so that your fingers on the radial pulse are above your fingers on the femoral pulse.

b. Vary the compression force until both pulse pressures feel equal.

c. Femorals are best found with the legs slightly abducted and the foot externally rotated.

By placing the patient's wrist over his or her femoral artery as you palpate both, you can best perceive the obvious delay of the femoral pulse peak over that of the arm. In using the radials rather than the brachials to test for differences between the arm and leg, you take advantage of the increased rapidity of pulse rise as you palpate more peripherally down the arm.

5. When may the femoral pulse be surprisingly easy to palpate in coarctation and so make the test for femoral peak delay especially useful?

ANS: When coexistent AR is present (as may occur with a bicuspid aortic valve).

Note: a. As many as 50% of patients with coarctation may have a bicuspid aortic valve, which is commonly regurgitant. b. Exercise will raise blood pressure to unexpectedly high levels in patients with coarctation.

Was this article helpful?

0 0
Blood Pressure Health

Blood Pressure Health

Your heart pumps blood throughout your body using a network of tubing called arteries and capillaries which return the blood back to your heart via your veins. Blood pressure is the force of the blood pushing against the walls of your arteries as your heart beats.Learn more...

Get My Free Ebook


Responses

  • vanessa grunwald
    Are there bounding pulses with coarctation of the aorta?
    9 years ago
  • JAN
    What is the best leg pulse for blood pressure?
    8 years ago
  • alistair
    How do one know cparctation pf aorta by comparing femoral and brachial pulse?
    3 years ago
  • Mollie
    What kind of pulses in coarctationof aorta?
    2 years ago
  • mohammed
    When to suspect coarctation of the aorta?
    10 months ago
  • Carla
    How to measure blood pressure in the lower extremities coarctation aortae?
    10 months ago
  • jacob
    Why blood presure is taken from the legs in coarctation of the aorta?
    9 months ago
  • Lloyd
    Why check bilateral femoral pulses for coarctation of the aorta?
    7 months ago

Post a comment