Mean Systolic Flow Velocity Research Articles

Aortic root stiffness affects the kinematics of bioprosthetic aortic valves.

In this study, the influence of aortic root distensibility on the haemodynamic parameters and valve kinematics of a bioprosthetic aortic valve was investigated in a controlled in vitro experiment. An Edwards INTUITY Elite 21 mm sutureless aortic valve (Edwards Lifesciences, Irvine, CA, USA) was inserted in three transparent aortic root phantoms with different wall thicknesses (0.55, 0.85 and 1.50 mm) mimicking different physiological distensibilities. Haemodynamic measurements were performed in an in vitro flow loop at heart rates of 60, 80 and 100 bpm with corresponding cardiac outputs of 3.5, 4.0 and 5.0 l/min and aortic pressures of 100/60, 120/90 and 145/110 mmHg, respectively. Aortic valve kinematics were assessed using a high-speed camera. The geometric orifice area (GOA) was measured by counting pixels in the lumen of the open aortic valve. The effective orifice area (EOA) was calculated from the root-mean-square value of the systolic aortic valve flow rate and the mean systolic trans-valvular pressure gradient. The tested aortic root phantoms reproduce physiological distensibilities of healthy individuals in age groups ranging from 40 to 70 years (±10 years). The haemodynamic results show only minor differences between the aortic root phantoms: the trans-valvular pressure gradient tends to increase for stiffer aortic roots, whereas the systolic aortic valve flow rate remains constant. As a consequence, the EOA decreased slightly for less distensible aortic roots. The GOA and the aortic valve opening and closing velocities increase significantly with reduced distensibility for all haemodynamic measurements. The resulting mean systolic flow velocity in the aortic valve orifice is lower for the stiffer aortic root. Aortic root distensibility may influence GOA and aortic valve kinematics, which affects the mechanical load on the aortic valve cusps. Whether these changes have a significant effect on the onset of structural valve deterioration of bioprosthetic heart valves needs to be further investigated.

Visual field loss in optic disc drusen patients correlates with central retinal artery blood velocity patterns

(1) To characterize the retrobulbar circulation in patients with optic disc drusen (ODD) using colour Doppler imaging; (2) to explore the differences in retrobulbar hemodynamics in patients with primary open-angle glaucoma (POAG). Retrospective analysis using three diagnostic groups: patients with ODD, age-matched healthy controls and age- and visual defect-matched patients with POAG. Subjects with history of ocular trauma or ocular diseases including vascular-related diseases were excluded. Kruskal-Wallis and Spearman's correlation tests were performed to compare and explore the correlations between the hemodynamic parameters and visual field damage. Sixty patients were included and equally divided between the three groups. Patients with ODD had lower systolic and diastolic flow velocities in the central retinal artery (CRA) when compared to healthy individuals, but no difference was found with the glaucoma group (p<0.005 versus healthy; p range 0.30-0.37 versus POAG). The systolic shift in flow patterns correlated with the extent of visual field defect in ODD patients (p<0.001, r=-0.78, confidence interval: -0.43 to -0.92), but not in POAG (p=0.73). Short ciliary arteries from ODD patients had lower mean systolic flow velocities when compared to both healthy individuals and patients with POAG (p<0.01 versus healthy; p≤0.04 versus POAG). The ophthalmic artery in ODD group had significantly higher mean blood velocities than in the POAG (p=0.04), while showing a significant overlap in Doppler waveform variables to the control group (p range 0.08-0.97). Similar to patients with glaucoma, individuals with ODD have low blood flow velocities in the vessels around the optic nerve head. Unlike patients with glaucoma, however, their CRA's blood flow velocity patterns correlate with the extent of the visual field defects.

Spiral phase velocity mapping of left and right coronary artery blood flow: Correction for through‐plane motion using selective fat‐only excitation

To develop a method of correcting both right and left coronary artery flow velocities for the through-plane motion of the vessel, in order to allow details in the temporal flow profiles to be viewed. The methods developed use selective excitation and velocity mapping of the epicardial fat surrounding the artery, either in a separate acquisition (temporal resolution = 22 msec) or interleaved with the water-excitation acquisition (temporal resolution = 44 msec) used to determine coronary blood flow velocities. The two methods were compared in 10 right and 13 left coronary arteries in healthy volunteers. For the right coronary arteries, correction for through-plane motion significantly reduces the mean systolic flow velocity (75.3 mm/second vs. 90.0 mm/second, P < 0.01), while the mean diastolic flow velocity is unchanged (96.8 mm/second vs. 94.5 mm/second, P = ns). The resulting profiles are biphasic, with approximately equal flow in systole and diastole. For the left arteries, correction for through-plane motion reduces the mean systolic flow velocity (25.0 mm/second vs. 72.8 mm/second, P < 0.001), resulting in the expected diastolic predominant flow profiles. For the right arteries, there were no significant differences in the mean systolic and mean diastolic velocities after correction with the separate fat-excitation acquisition, and after correction the poorer temporal resolution combined water excitation/fat excitation acquisition. However, for the left coronary arteries, the combined water excitation/fat excitation acquisition resulted in a slight reduction in the mean diastolic velocity (121.5 mm/second vs. 130.9 mm/second, P < 0.05). Selective excitation of the surrounding epicardial fat enables through-plane correction of both left and right coronary flow velocities, enabling the temporal details of flow velocity to be viewed. With a combined WE/FE acquisition, this can be performed without extending the study duration; however, the reduced temporal resolution and temporal mismatch of the excitations results in a blunting of rapidly changing flow profiles. As such, it may be less suitable for the left coronary artery, which has a greater range of through-plane motion than the right, and correction using separate WE and FE acquisitions, or the adjacent myocardium, may be preferable.

Comparison of vertebral artery velocity and flow volume measurements for diagnosis of vertebrobasilar insufficiency using color duplex sonography

Introduction: The aim of this study was to compare the measurements of vertebral artery (VA) systolic flow velocity and flow volume for diagnosis of vertebrobasilar insufficiency (VBI). Material and methods: We examined 96 patients who were referred for evaluation of VBI. Net vertebral artery flow volume and mean systolic flow velocity were determined by using color duplex sonography. We had grouped the patients into three according to VA flow volume: group 1 was consisted of patients with severely damped VA flow volume (lower than 120 mL/min), group 2 was consisted of patients with moderately damped VA flow volume (120–200 mL/min), group 3 was consisted of patients with normal VA flow volume (>200 mL/min). The mean systolic flow velocities in each group were compared by one-way ANOVA. Results: Mean VA systolic flow velocities of groups 1, 2 and 3 were 32 ± 12, 42 ± 10 and 46 ± 8 cm/s, respectively. Mean VA systolic flow velocity in group 1 was significantly lower than that of group 2 ( P = 0.001). However, there were no significant differences between VA systolic flow velocities in groups 2 and 3 ( P = 0.2). Conclusions: According to our findings, measurement of volume in addition to velocity is more valuable in detection of moderately damped VA flow volumes in diagnosis of VBI.

Transesophageal doppler echocardiographic assessment of left coronary blood flow velocity in chronic aortic regurgitation

Assessment of systolic and diastolic coronary blood flow velocities (FVs) in patients with aortic regurgitation (AR) has remained a clinical challenge. We recorded left anterior descending coronary blood FV in 21 patients with chronic AR and in 6 control subjects using transesophageal pulsed Doppler echocardiography. In 7 patients FV was measured 4.0 ± 5.2 months after aortic valve replacement. Peak and mean FVs during systole and diastole and the systolic/diastolic ratios of these FVs were determined. Left ventricular (LV) mass index was calculated by means of standard M-mode echocardiography. In patients with severe AR, peak and mean systolic FVs were significantly increased (34 ± 8 cm/sec and 21 ± 6 cm/sec, respectively) compared with FVs in the control group (15 ± 4 and 12 ± 3 cm/sec, respectively) and in patients with mild AR (17 ± 3 cm/sec and 13 ± 2 cm/sec, respectively). Peak and mean diastolic FVs were also significantly increased in severe AR (54 ± 13 cm/sec and 33 ± 9 cm/sec, respectively) compared with FVs in the control (30 ± 8 cm/sec and 21 ± 5 cm/sec, respectively) and mild AR groups (30 ± 5 cm/sec and 21 ± 4 cm/sec, respectively). Peak systolic and diastolic FVs were correlated significantly with LV mass index ( r = 0.72 and r = 0.73, respectively). Systolic and diastolic FVs and LV mass index were significantly decreased, normalized, or both after aortic valve surgery. In conclusion, LV mass seems to have an effect on the significantly increased systolic and diastolic left coronary blood FV pattern in patients with chronic, severe AR. Increased systolic and diastolic FV appears to be normalized in the late period after surgery.

Increased sensitivity of flow detection in the left coronary artery by transesophageal echocardiography after intravenous administration of transpulmonary stable echocontrast agent.

Transesophageal echocardiography (TEE) combined with color and pulsed Doppler allows a noninvasive assessment of flow in the proximal anterior descending coronary artery (LAD). The aim of this study was to assess whether the peripheral administration of a transpulmonary stable echocontrast agent with prolonged in vivo stability may improve the feasibility and accuracy of coronary flow detection by TEE Doppler. In 12 out of 14 consecutive patients undergoing routine diagnostic TEE examination, color-coded images of left main coronary artery (LM) and the origin of the LAD and circumflex artery (CXA), as well as spectral Doppler signals from the LAD, were evaluated before and after intravenous injection of SHU 508 A. After administration of echocontrast material, the coronary Doppler signal (both color-coded and spectral) was enhanced for approximately 100 seconds. The length and diameter of color-coded flow increased significantly in the LM, LAD, and CXA. (The length of color-coded flow before and after injection of contrast material were the following: in LM 0.94 +/- 0.44 versus 1.39 +/- 0.52 cm, p < 0.001; in LAD 0.68 +/- 0.36 versus 1.20 +/- 0.41 cm, p < 0.001; and in CXA 0.54 +/- 0.20 versus 1.06 +/- 0.86 cm; in this artery, color-coded flow was visualized only in six patients before and 11 patients after injection of contrast material. The corresponding values for the diameters of color-coded flow in LM were 0.36 +/- 0.08 versus 0.46 +/- 0.09 cm, p < 0.001; in LAD 0.29 +/- 0.07 versus 0.41 +/- 0.1 cm, p < 0.002; and in CXA 0.26 +/- 0.05 versus 0.40 +/- 0.04 cm.) By pulsed Doppler, significant increments in peak diastolic (47.8 +/- 21.3 versus 37.2 +/- 14.5 cm/sec, p < 0.05), mean diastolic (37.4 +/- 14.7 versus 27.9 +/- 8.4 cm/sec, p < 0.005), mean systolic flow velocity (23.2 +/- 6.8 versus 19.0 +/- 4.7 cm/sec, p < 0.005), and diastolic (11.0 +/- 3.9 versus 7.7 +/- 3.0 cm, p < 0.001) and total flow integral (16.8 +/- 5.3 versus 10.5 +/- 4.6 cm, p < 0.001) were observed. By contrast, peak systolic velocity did not increase. However, the systolic component of coronary flow, detectable in 7 out of 12 patients before injection of contrast material, became detectable in all 12 patients after injection of contrast material.(ABSTRACT TRUNCATED AT 400 WORDS)

Pulmonary venous flow velocity pattern as assessed with transthoracic pulsed Doppler echocardiography in subjects without cardiac disease

Pulmonary venous flow velocity pattern (PVFVP) was analyzed in 53 subjects (aged 25 to 77 years, mean 47) without cardiovascular disease who underwent transthoracic pulsed Doppler echocardiography. The forward flow velocity pattern was biphasic in 37 of the 53 subjects, with each of the 2 peaks in systole and diastole; flow was triphasic with 2 peaks in systole and the other peak in diastole in the remaining 16 subjects. Peak systolic and diastolic flow velocity ranged from 28 to 84 cm/s and from 27 to 71 cm/s, respectively. Mean systolic flow velocity was significantly greater than mean diastolic flow velocity (53 ± 12 vs 47 ± 11 cm/s, p < 0.01). Systolic flow velocity and the ratio of systolic to diastolic flow velocity increased and diastolic flow velocity decreased with aging (r = 0.52, p < 0.001, r = 0.70, p < 0.001 and r = −0.49, p < 0.001, respectively). Reverse flow occurred during the atrial contraction phase and its velocity (mean 20 cm/s) increased with aging (r = 0.56, p < 0.001). The parameters of PVFVP were compared with the ratio of peak early diastolic filling velocity to peak filling velocity at atrial contraction ( E A ratio) measured in the transmitral flow velocity pattern. As E A ratio increased, systolic flow velocity and systolic/ diastolic flow ratio and peak reverse flow velocity decreased (r = −0.40, p < 0.01, r = −0.67, p < 0.001 and r = −0.68, p < 0.001, respectively) and diastolic flow velocity increased (r = 0.58, p < 0.001). Thus, PVFVP can be assessed in adults by using transthoracic pulsed Doppler echocardiography. PVFVP is significantly affected by aging, at least partially reflecting altered left ventricular diastolic function with aging. These results can be used for comparison with patterns found in disease states.