Saturday, 4 June 2011

Windkessel Effect (and Large Artery Physiology)

Windkessel Effect Basic Details:
  • Windkessel in German means 'air chamber'.
  • Term implies an elastic reservoir in large arteries.
Windkessel Effect Mechanism:
  • Distension of the aorta following ejection of blood from the left ventricle during systole.
  • The distended aorta then recoils during diastole, smoothing out pressure & blood flow.
  • The walls of large elastic arteries (eg. aorta, common carotid, subclavian, & their larger branches, plus pulmonary artery) contain elastic fibers which are composed of elastin.
  • These same arteries distend when the blood pressure rises during systole & then recoil when the blood pressure falls during diastole. 
  • The rate of blood entering these elastic arteries significantly exceeds that leaving them due to arterial peripheral resistance.
  • This results in a net storage of blood during systole which unloads during diastole.
Windkessel Effect Accomplishes the following:
  • Decreases pulse pressure during cardiac cycle.
  • Increased efficiency of pumping of the left ventricle.
  • Provides more continuous flow.
  • Contributes to organ perfusion during diastole when cardiac ejection ceases.
  • Specifically helps the perfusion of the coronary arteries during diastole.
Ageing & The Windkessel Effect:
  • Diminution of the Windkessel effect occurs with age.
  • Associated with the elastic arteries becoming less compliant.
  • Pathologically related to 'hardening of the arteries' or arteriosclerosis where there is fragmentation & loss of elastin in the arteries.
  • Clinically results in increased pulse pressure, systolic pressure & cardiac oxygen consumption for any given cardiac stroke volume.
  • The consequences of these pathophysiological changes include greater risks for myocardial infarction, cardiac enlargement, heart failure, stroke, peripheral vascular disease & renal damage.

Tags: Aorta - Arteriosclerosis - Diastole - Elastic Fibers - Elastin - Pulse Pressure - Systolic Blood Pressure - Windkessel Effect - Systole - Vascular Disease
Posted by Medicalchemy
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Sunday, 24 October 2010

Impact Of Diffuse Vascular Disease On Survival Following A Diagnosis of Peripheral Arterial Disease (PAD)


Impact Of Diffuse Vascular Disease On Survival Following A Diagnosis of Peripheral Arterial Disease (PAD):
Important Points:
  • Patients with PAD and a history of diffuse vascular disease (DVD) are more likely to die.
  • Kaplan-Meier survival curve, p <>
  • Median survival (in years) is progressively worse for patients with a history of:
    • MI (9.3 years)
    • TIA (6.3 years)
    • Stroke (4.7 years)
    • MI+stroke (4.1 years)
    • Compared to the PAD only subgroup (9.9 years)
Reference (including Image):
Kristen Migliaccio-Walle , Michael Stokes , Irina Proskorovsky , Dan Popovici-Toma and Wissam El-Hadi.
Evaluation of the consequences associated with diffuse vascular disease history in patients diagnosed with peripheral arterial disease: estimates from Saskatchewan health data.
BMC Cardiovascular Disorders 2010, 10:40doi:10.1186/1471-2261-10-40

Image: Kaplan-Meier Survival Curve.
Tags: Kaplan-Meier Survival Curve - Peripheral Arterial Disease - Survival - Vascular Disease 
Posted by Medicalchemy
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Saturday, 16 October 2010