1. Non-invasive aortic compliance measurements have been used previously to assess the distensibility of the aorta in several pathological conditions associated with increased cardiovascular risk. We set out to establish whether aortic compliance is abnormal in patients with stroke.
2. Pulse wave velocity measurements of thoracoabdominal aortic compliance were made in 20 stroke patients and 25 age- and sex-matched hospitalized, non-stroke control subjects putatively free of cardiovascular disease. Since compliance varies with non-chronic changes in blood pressure, a blood pressure corrected index of aortic distensibility, Cp, was calculated.
3. Aortic compliance was significantly reduced in patients with stroke compared with non-stroke control subjects (0.46 ± 0.27 versus 0.86 ± 0.34%/10 mmHg, P < 0.0002), corresponding with higher values for pulse wave velocity. Stroke patients also had significantly higher systolic and diastolic blood pressures (P < 0.02 and P < 0.002 respectively) and total cholesterol levels (P < 0.004) than the control subjects. Calculation of Cp did not alter the observation of stiffer aortas in the stroke cohort (P < 0.0007).
4. In both stroke patient and control cohorts, as expected, inverse trends were observed between aortic compliance and blood pressure. Also as expected, in the control group Cp values did not show a relationship with blood pressure (r = 0.02, P = 0.092, not significant). However, in the stroke cohort a marked dependence of Cp on blood pressure was observed (r = −0.48, P = 0.03).
5. Transoesophageal echocardiographic studies have recently identified advanced atherosclerosis in the ascending aorta as a possible source of cerebral emboli and an independent risk factor for ischaemic stroke. Our observations of significantly stiffer thoracoabdominal aortas in patients with stroke lead us to hypothesize that a totally non-invasive assessment of aortic compliance may potentially prove a useful surrogate marker of such atherosclerotic risk.
6. Blood pressure-corrected indices of arterial elastic properties based on normotensive models are widely applied in the literature. Our observation that these indices exhibit a considerable blood pressure dependence leads us to urge caution in the use of such corrections, especially in hypertensive patients.
Heart rate and blood pressure dependence of aortic distensibility in rats: comparison of measured and calculated pulse wave velocity