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12.11.29 Pulses

Unequal or Delayed
  • Obstructive arterial diseases
    • Most commonly atherosclerosis
  • Aortic dissection
  • Aortic aneurysm
  • Takayasu's disease
  • Supravalvular aortic stenosis 
    • Right carotid, brachial, and radial pulses are larger in amplitude and volume than those on the left side 
    • Due to preferential streaming of the jet toward the innominate artery
  • Coarctation of the aorta
    • Delay in onset of femoral pulse

Pulsus alternans
  • Definition 
    • Variation in pulse amplitude occurring with alternate beats due to changing systolic pressure
  • Aetiology
    • Left ventricular failure
  • Other rare causes
    • Hypertrophic cardiomyopathy and a significant rest or provocable outflow gradient
    • Cardiac tamponade
    • Severe aortic regurgitation
  • Apparent pulsus alternans
    • Due to bigeminal rhythm
  • Mechanism unclear
    • Alternating preload (Frank-Starling mechanism) and incomplete relaxation have been proposed
    • Changes in afterload, which is lower after preceding the strong beat, may also contribute

Pulsus paradoxus
  • Definition
    • Inspiratory decrease in arterial pressure exceeding 20 mmHg
  • Aetiology
    • Cardiac tamponade
    • COPD
    • Hypovolemic shock
    • Constrictive pericarditis 
    • Restrictive cardiomyopathy
  • Mechanism
    • Inspiratory decline of left ventricular stroke volume due to an increase in right ventricular end-diastolic volume and decreased left ventricular end-diastolic volume

Pulsus bisferiens
  • Definition
    • Two systolic peaks of the aortic pulse during left ventricular ejection separated by a midsystolic dip
  • Aetiology
    • Aortic regurgitation
      • Common in patients with combined aortic stenosis and aortic regurgitation
    • PDA or arteriovenous fistula
  • Mechanism
    • Unclear
    • Appears to be related to a large, rapidly ejected left ventricular stroke volume associated with increased left ventricular and aortic dp/dt
  • Pitfalls
    • Difficult to establish with certainty that the two peaks are occurring in systole
    • (One peak in systole and the other in diastole = Dicrotic pulse)

Dicrotic pulse
  • Definition
    • Accentuated diastolic dicrotic wave that follows the dicrotic notch
  • Aetiology
    • Severe heart failure
    • Hypovolemic shock
    • Cardiac tamponade
    • Conditions associated with a decreased stroke volume and elevated systemic vascular resistance
  • Mechanism
    • Tends to occur when the dicrotic notch is low (decreased systemic arterial pressure and vascular resistance)
  • Pitfall
    • Frequently confused with pulsus bisferiens at the bedside
    • It is almost impossible to distinguish between these two types of pulse configurations without a pulse recording

Corrigan pulse
  • Definition
    • Abrupt, very rapid upstroke of the peripheral pulse (percussion wave), followed by rapid collapse
  • Aetiology
    • Chronic, hemodynamically significant aortic regurgitation
  • Mechanism
    • Rapid ejection of a large left ventricular stroke volume into a low resistance arterial system

Anacrotic pulse
  • Definition
    • Interruption of the upstroke of the carotid pulse
  • Aetiology
    • Aortic stenosis

Pulsus tardus
  • Definition
    • Delayed upstroke of the ascending limb 
  • Aetiology
    • Aortic stenosis
  • Mechanism
    • Prolonged left ventricular ejection time

Notes
  • Dicrotic notch
    • Coresponds to aortic valve closure
    • Just as the ventricles enter into diastole, the brief reversal of flow from the aorta back into the left ventricle causes the aortic valves to shut
    • This results in the slight increase in aortic pressure caused by the elastic recoil of the semilunar valves and aorta



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