Assessment of arterial compliance by carotid midwall strain-stress relation in hypertension

To elucidate the relations between arterial hypertrophy and compliance in h ypertension, we studied 205 unmedicated hypertensive patients (129 men and 76 women) and 82 normotensive adults (56 men and 26 women) from an employed population by carotid ultrasound, noninvasive applanation tonometry, and e chocardiography. Carotid midwall strain and circumferential stress were cal culated at end diastole and peak systole. The relations of luminal and midw all strain to the increment in circumferential stress from end diastole to peak systole (Delta carotid stress in normal subjects) were used to calcula te ratios of observed/predicted carotid luminal and midwall strain. Mean st ress-corrected luminal strain (82+/-26%) and midwall strain (78+/-23%) were lower (both P<0.001) in hypertensive patients than in normal adults. Stres s-corrected luminal strain identified 14% of hypertensive patients with low arterial compliance, while stress-corrected midwall strain was low in 188 of patients. Patients with subnormal carotid midwall strain were older (61/-12 versus 54+/-12 years, P<0.01) and had larger carotid diameters (6.6+/- 0.8 versus 5.7+/-0.8 mm, P=0.002) and higher brachial pulse pressures (71+/ -25 versus 63+/-17 mm Hg, P<0.05) than other patients. Patients with arteri al hypertrophy had lower stress-corrected midwall strain than those without hypertrophy (70+/-24% versus 79+/-23%, P=0.05), whereas no difference was observed in stress-corrected luminal strain (P=0.30). Stress-corrected midw all strain tended to be lower in patients with discrete atherosclerotic pla ques than in those without (74+/-20% versus 79+/-24%, P=0.15). Compared wit h patients with normal left ventricular geometry, those with concentric hyp ertrophy had larger carotid diameters (6.6+/-0.7 versus 5.8+/-0.9 mm, P<0.0 5) and lower stress-corrected luminal strain (62+/-11% versus 85+/-25%, P<0 .05) and midwall strain (59+/-10% versus 81+/-22%, P<0.05). Therefore, stre ss-corrected midwall strain identifies patients with reduced arterial compl iance, increased arterial wall thickness, and abnormal left ventricular geo metry better than conventional measures based on arterial lumen diameters.