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Arterial stiffening and vascular/ventricular interaction
1School of Medicine, University of New South Wales, St. Vincent's Hospital, Darlinghurst, Sydney, Australia.
Insights
Arterial stiffness significantly impacts systolic pressure, especially in central arteries. A new method synthesizes aortic pressure from arm measurements, revealing how certain blood pressure medications reduce aortic pressure augmentation without affecting arm pressure.
Area of Science:
- Cardiovascular Physiology
- Biomedical Engineering
- Pharmacology
Background:
- Arterial stiffness, a key factor in systolic pressure, increases with age and hypertension, particularly in central elastic arteries.
- Conventional brachial artery pressure measurements underestimate the effects of arterial stiffening on central aortic and left ventricular systolic pressure due to pressure wave transmission.
- Accurate assessment of central systolic pressure is crucial for understanding cardiovascular risk and optimizing hypertension treatment.
Purpose of the Study:
- To develop and validate a method for synthesizing the ascending aortic pressure wave from peripheral arterial pressure waveforms.
- To assess the impact of arterial stiffening on central systolic pressure augmentation.
- To evaluate the effects of antihypertensive drug therapies on central systolic pressure augmentation.
Main Methods:
- Synthesizing the ascending aortic pressure wave from invasive (arterial cannula) or noninvasive (applanation tonometry) radial or brachial artery pressure recordings.
- Comparing synthesized aortic pressure waveforms with directly measured carotid artery pressure waves.
- Measuring systolic pressure augmentation in the ascending aorta before and after administration of various antihypertensive medications.
Main Results:
- The synthesized ascending aortic pressure waveform provides consistent results, comparable to carotid artery pressure measurements.
- Arterial stiffening leads to significant augmentation of late systolic pressure in the ascending aorta.
- Vasodilating drugs (nitrates, ACE inhibitors, calcium antagonists) effectively reduce ascending aortic pressure augmentation by decreasing wave reflection, often without altering brachial or radial systolic pressure.
Conclusions:
- Synthesizing the ascending aortic pressure wave is a valuable tool for assessing central hemodynamics and the effects of arterial stiffening.
- Certain antihypertensive medications targeting peripheral vasodilation are more effective in reducing central systolic pressure augmentation than beta-blockers or diuretics.
- This approach offers a more accurate way to evaluate therapeutic interventions for isolated systolic hypertension.
Abstract:
Arterial stiffness is the major determinant of systolic pressure and increases with age and hypertension, especially in the thoracic aorta and major central elastic arteries. The effects of arterial stiffening on aortic and left ventricular systolic pressure are underestimated when taken from conventional recordings of systolic pressure in the brachial artery or in other arteries of the upper limb, as a consequence of pressure wave transmission in the upper limb. A method has been devised to synthesise the ascending aortic pressure wave from the radial or brachial artery pressure wave, as measured invasively by arterial cannula or noninvasively by applanation tonometry. Results obtained in this way are similar to, but more consistent than, those obtained through measurement of carotid artery pressure waves by applanation tonometry. The ability to synthesise the ascending aortic waveform enables one to measure augmentation of late systolic pressure caused by arterial stiffening as well as the effects of antihypertensive drug therapies on systolic pressure augmentation. Results have shown that drugs which dilate small peripheral arteries and thereby reduce wave reflection (nitrates, ACE inhibitors, calcium antagonists) reduce ascending aortic pressure augmentation during systole, often without corresponding reduction in brachial or radial artery systolic pressure. These agents are more appropriate therapy for isolated systolic hypertension than beta-blockers and diuretics.