End-diastolic Aortic Diameters Research Articles

Aortic Root Dimensions in Elite Athletes

Although cardiac adaptation to different sports has been extensively described, the potential effect of top-level training on the aortic root dimension remains not investigated fully. To explore the full range of aortic root diameters in athletes, 615 elite athletes (370 endurance-trained athletes and 245 strength-trained athletes; 410 men; mean age 28.4 +/- 10.2 years, range 18 to 40) underwent transthoracic echocardiography. The end-diastolic aortic diameters were measured at 4 locations: (1) the aortic annulus, (2) the sinuses of Valsalva, (3) the sinotubular junction, and (4) the maximum diameter of the proximal ascending aorta. Ascending aorta dilation at the sinuses of Valsalva was defined as a diameter greater than the upper limit of the 95% confidence interval of the overall distribution. The left ventricular (LV) mass index and ejection fraction did not significantly differ between the 2 groups. However, the strength-trained athletes had an increased body surface area, sum of wall thickness (septum plus LV posterior wall), LV circumferential end-systolic stress, and relative wall thickness. In contrast, the left atrial volume index, LV stroke volume, and LV end-diastolic diameter were greater in the endurance-trained athletes. The aortic root diameter at all levels was significantly greater in the strength-trained athletes (p <0.05 for all comparisons). However, ascending aorta dilation was observed in only 6 male power athletes (1%). Mild aortic regurgitation was observed in 21 athletes (3.4%). On multivariate analyses, in the overall population of athletes, the body surface area (p <0.0001), type (p <0.001) and duration (p <0.01) of training, and LV circumferential end-systolic stress (p <0.01) were the only independent predictors of the aortic root diameter at all levels. In conclusion, the aortic root diameter was significantly greater in elite strength-trained athletes than in age- and gender-matched endurance athletes. However, significant ascending aorta dilation and aortic regurgitation proved to be uncommon.

Aortic distensibility and compliance in conscious pregnant rats.

In pregnancy, complex hormonal and hemodynamic changes develop. In this study, we tested the hypothesis that these pregnancy-associated changes are accompanied by an alteration of the compliance of central conduit vessels. To this end, we determined in awake, restrained pregnant rats the distensibility (DC) and compliance (CC) coefficients of the descending thoracic aorta. End diastolic aortic diameter (d) and changes in aortic diameter during the cardiac cycle (delta d) were measured noninvasively by ultrasound, simultaneously with diastolic aortic blood pressure (Pdia) and pulse pressure (delta P) through a chronically implanted catheter. From these parameters, DC and CC (expressed as the relative and the absolute increase, respectively, in lumen cross-sectional area for a given increase in P) were calculated. Nine rats were studied before pregnancy and, on days 4, 8, 10, and 18 of pregnancy, were matched for age and days postsurgery with eight nonpregnant rats. On day 20, the animals were killed and the thoracic aorta was isolated for morphometric analysis. In the pregnant group, Pdia decreased from 109 +/- 5 mmHg on day 4 to 98 +/- 9 mmHg on day 18 (means +/- SD), whereas d did not change. delta d increased from 242 +/- 20 microm on day 4 to 271 +/- 29 microm on day 18. delta P did not change. Both DC and CC increased in early pregnancy to a plateau reached by day 10. The increase in DC and CC preceded the fall in Pdia. On day 20, neither cross-sectional area nor thickness of the aortic media had changed significantly, when compared with the nonpregnant group. In the nonpregnant group, none of the variables changed consistently during the study period. On the basis of these results, we conclude that CC of the thoracic aorta increases in early pregnancy. We speculate that the increased aortic CC and DC and the decreased total peripheral resistance develop in early pregnancy in response to the increase in stroke volume, thus preventing a concomitant rise in arterial wall stress.

Isoflurane and halothane produce similar alterations in aortic distensibility and characteristic aortic impedance.

The effects of volatile anesthetics on arterial mechanical properties in vivo are incompletely understood. The present investigation tested the hypothesis that isoflurane and halothane cause differential actions on the mechanical characteristics of the aorta in barbiturate-anesthetized dogs instrumented for measurement of aortic blood pressure, blood flow, and diameter. Aortic distensibility and characteristic aortic impedance were calculated from aortic diameter measurements. Oscillatory (Wo) and mean (Wm) hydraulic power were determined from aortic pressure and blood flow waveforms. Hemodynamics and aortic pressure, blood flow, and diameter were recorded before, during, and after 0.5, 0.75, and 1.0 minimum alveolar anesthetic concentration (MAC) (end-tidal) isoflurane (n = 7), or halothane (n = 8). Isoflurane and halothane caused significant (P < 0.05) and dose-related decreases in heart rate, mean arterial pressure, peak and end-diastolic aortic diameters, and aortic distensibility (e.g., from 0.16% +/- 0.03% during control to 0.24% +/- 0.04% mm Hg during 1.0 MAC isoflurane). Characteristic aortic impedance remained unchanged by either drug. In contrast to the findings with isoflurane, halothane increased the ratio of Wo to Wm (from 6.7 +/- 1.1 during control to 11.3 +/- 3.1 x 10(-2) during 1.0 MAC), suggesting that this drug decreases left ventricular mechanical efficiency. The results indicate that isoflurane and halothane do not alter characteristic aortic impedance and produce similar increases in aortic distensibility concomitant with reductions in aortic pressure. These findings support the contention that volatile anesthetic-induced alterations in aortic mechanical properties do not contribute to the differential effects of these drugs on left ventricular afterload in vivo.

A technique to assess aortic distensibility and compliance in anesthetized and awake rats.

A noninvasive ultrasonic technique, based on tracking arterial wall displacements with a vessel wall-tracking device attached to a conventional B-mode imager, to assess end-diastolic aortic diameter (d) and aortic diameter changes during the cardiac cycle (delta d) in anesthetized and awake rats is presented. From these parameters and invasively measured aortic pulse pressure (delta P), aortic distensibility and compliance, the relative and absolute increases in lumen cross-sectional area for a given increase in delta P, respectively, can be calculated. d, delta d, and delta P could be determined with good intra-session (variations per day) and inter-session (variations between days) coefficients of variation (CV). The CVs for delta d were smaller in awake (4.6-6.0%) than in anesthetized rats (7.9-11.0%), probably due to variations in delta P during anesthesia (CV: 9.0-12.3%). The CVs for d in awake (3.3-6.5%) and anesthetized rats (2.6-5.0%) were comparable. In awake rats the CV for delta d, but not for d, increased after implantation of the aortic catheter. It is concluded that d, delta d, and delta P of the aorta can be reliably measured noninvasively in anesthetized and awake rats, allowing the in vivo assessment of aortic distensibility and compliance. The technique is sensitive enough to detect effects of agents on aortic wall properties.