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Biomedical subjects

J N Bella

Publications and source records attributed to J N Bella.

4 recordsLinked to original sources
PubMed1999

Assessment of arterial compliance by carotid midwall strain-stress relation in normotensive adults.

Examining left ventricular midwall as opposed to endocardial mechanics enhances understanding of left ventricular function in individuals with abnormal cardiac geometry. Accordingly, we used carotid ultrasound and applanation tonometry of arterial pressure to derive carotid midwall strain and its relation to carotid peak-systolic and end-diastolic stresses in 82 apparently normal, employed subjects (56 men, 26 women; median age, 47 years; 70% white; 21% overweight) with no evidence of coronary or valvular heart disease. Regression equations relating carotid luminal and midwall strain to the increment in carotid stress during systole (Deltacarotid stress) were used to predict strain for the observed Deltastress. Observed/predicted carotid luminal or midwall strain was calculated as a measure of carotid luminal or midwall strain for imposed stress, termed stress-corrected strain. Midwall carotid strain was similar in women and men but was negatively related to older age (r=-0.35, P=0.001) and higher body mass index (r=-0.31, P=0.005) and brachial and carotid blood pressure (r=-0.30 to -0.45, all P<0.01). The pulsatile change in arterial load, measured by Deltacarotid stress, was positively related to midwall strain (r=0. 44, P<0.001) more closely than was carotid luminal strain. Regression analyses revealed that carotid midwall strain was positively related to Deltastress, with additional negative relations to age and carotid diastolic diameter (all P<0.001). Stress-corrected carotid midwall strain was strongly and negatively correlated with midwall elastic modulus and Young's modulus (both r=-0.77, P<0.001), followed by elastic modulus (r=-0.74, P<0.001), midwall Young's modulus (r=-0.73, P<0.001), midwall stiffness index (r=-0.70, P<0.001), and stiffness index (r=-0.66, P<0.001). Thus, in normal adults, carotid midwall strain is unrelated to gender, is positively related to pulsatile carotid load as measured by Deltacarotid stress, and is negatively related to age, overweight, and standard measures of arterial stiffness.

Age Factors↗
PubMed1999

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

To elucidate the relations between arterial hypertrophy and compliance in hypertension, 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 echocardiography. Carotid midwall strain and circumferential stress were calculated at end diastole and peak systole. The relations of luminal and midwall strain to the increment in circumferential stress from end diastole to peak systole (Deltacarotid stress in normal subjects) were used to calculate ratios of observed/predicted carotid luminal and midwall strain. Mean stress-corrected luminal strain (82+/-26%) and midwall strain (78+/-23%) were lower (both P<0.001) in hypertensive patients than in normal adults. Stress-corrected luminal strain identified 14% of hypertensive patients with low arterial compliance, while stress-corrected midwall strain was low in 18% 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 arterial 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=0.40). Stress-corrected midwall strain tended to be lower in patients with discrete atherosclerotic plaques than in those without (74+/-20% versus 79+/-24%, P=0.15). Compared with patients with normal left ventricular geometry, those with concentric hypertrophy had larger carotid diameters (6.6+/-0.7 versus 5.8+/-0.9 mm, P<0.05) 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, stress-corrected midwall strain identifies patients with reduced arterial compliance, increased arterial wall thickness, and abnormal left ventricular geometry better than conventional measures based on arterial lumen diameters.

Blood Pressure↗
PubMed1998

Relations of left ventricular mass to fat-free and adipose body mass: the strong heart study. The Strong Heart Study Investigators.

BACKGROUND: It is unclear whether increased left ventricular (LV) mass in overweight individuals is related to their adiposity or to greater fat-free mass (FFM). METHODS AND RESULTS: We compared echocardiographic LV mass to FFM and adipose body mass by bioelectric impedance and to anthropometric measurements in 3107 American Indian participants in the Strong Heart Study. In men and women, the relations of LV mass and FFM (r=0.37 and 0.38, P<0.001) were closer (P<0.05 to <0.001) than they were with adipose mass, waist/hip ratio, body mass index, systolic blood pressure, height, or height2.7. Regression analyses showed that in men LV mass had the strongest independent relation with FFM, followed by systolic blood pressure and age (all P<0.001); in women, LV mass was related to FFM more strongly than it was to systolic blood pressure, age (all P<0. 001), and diabetes (P=0.012). Adipose mass had no independent relation to LV mass. When waist/hip ratio or body mass index were substituted for adipose mass, LV mass was independently related to FFM (P<0.001) and body mass index (P=0.02) but not to waist/hip ratio in men and was independently related to FFM and waist/hip ratio (both P<0.001) but not to body mass index in women. Using 97.5 percentile gender-specific partitions for LV mass/FFM in reference individuals, we found that LV hypertrophy occurred in 20.8% of Strong Heart Study participants with hypertension, overweight, or diabetes compared with 10.5% and 16.7% by LV mass indexed for body surface area or height2.7. CONCLUSIONS: LV mass is more strongly related to FFM than to adipose mass, waist/hip ratio, body mass index, or height-based surrogates for lean body weight; LV mass/FFM criteria may increase sensitivity to detect LV hypertrophy.

Adipose Tissue↗