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Atrial fibrillation and other arrhythmias
Published in Neeraj Parakh, Ravi S. Math, Vivek Chaturvedi, Mitral Stenosis, 2018
Neeraj Parakh, Vivek Chaturvedi
Age and LA size are the most significant risk factors for the development of AF (Table 18.1). Various studies have reported mean LA size from 43–57 mm as risk factors for the development of AF.5,10,11 The involvement of multiple valves is also an important risk factors. Left-atrial strain and flow velocities on echocardiography, LV ejection fraction, and right-atrial pressure have also been reported to be associated with AF.12 The relationship of AF with the severity of MS is not well established. In most of the studies, mitral valve area is not an independent risk factor for AF;13–16 however, Moreyra et al. found that smaller valve area along with higher LA and pulmonary artery pressure are associated with greater prevalence of AF.17 In asymptomatic patients with mild to moderate MS, peak LA strain on speckle tracking may predict future development of AF by detecting atrial dysfunction earlier than conventional 2D echocardiography.18 A decrease in the atrial systolic component of mitral flow velocity time integral (A-VTI) has been found to be useful in predicting future development of AF in severe MS in sinus rhythm. A-VTI is a marker of atrial pump function and a decrease in atrial pump function is shown to be a precursor to the development of AF. The percentage contribution of A-VTI to the total VTI of 9% or less was 84% sensitive and 80% specific for predicting the development of AF at one year.19 Certain biochemical markers such as NT-proBNP and CRP have also been found to be raised in AF, but their cause-effect association has not been established.9
Left ventricular dimensions and function
Published in Helen Rimington, John B. Chambers, Echocardiography, 2015
Helen Rimington, John B. Chambers
Stroke distance is measured using pulsed Doppler in the left ventricular outflow tract in the 5-chamber view and is also referred to as the velocity time integral (VTIsubaortic). Normal ranges in subjects aged approximately 20–80 are given in Table 2.8. In this population the values did not change materially with age.
Doppler physics
Published in Andrew R. Houghton, MAKING SENSE of Echocardiography, 2013
Measurement of flow volume in a tube can, for a constant flow rate, be calculated simply by multiplying the cross-sectional area of the tube by the flow velocity. However, blood flow is pulsatile, not constant, so to calculate flow volume (mL per heartbeat) it is necessary to measure the cross-sectional area of the region of interest and to measure the velocity time integral (VTI) of flow in that region. VTI is measured by integrating the area under the spectral envelope – this can easily be achieved by tracing the outline of the spectral Doppler envelope and allowing the echo machine software to calculate the VTI. VTI is measured in cm and represents the stroke distance – the distance travelled by a column of blood in the region of interest during one flow period (Fig. 4.7). To measure cross-sectional area (CSA), measure the diameter of the region where the spectral Doppler trace was obtained:
Renal echography for predicting acute kidney injury in critically ill patients: a prospective observational study
Published in Renal Failure, 2020
Hai Jun Zhi, Yong Li, Bo Wang, Xiao Ya Cui, Meng Zhang, Zhen Jie Hu
Transthoracic echocardiography was performed at the same time as RRI and semiquantitative PDU score measurements. Cardiac output was calculated from the left ventricular outflow tract (LVOT), as described by McLean et al. [23]. The diameter of the LVOT was taken to be the distance between the bases of the aortic valve cusp during systole, as seen from the long parasternal view. Pulsated wave Doppler samples were then obtained in the center of the LVOT from the apical view, paying close attention to obtaining an angle of Doppler signal to aortic blood flow close to 0° (<20°). The leading edge of five consecutive Doppler velocity curves was traced, and the average velocity time integral (VTI) was calculated. The body surface area (BSA) was calculated as follows (height was in cm and weight was in kg): BSA (m2) = 0.0061 × height + 0.0128 × weight − 0.1529. Thus, CI was thereafter calculated as follows (LVOT diameter and VTI were in cm): CI (L·min−1·[m2]−1) = (LVOT diameter/2)2×3.14 × VTI × HR × BSA−1 × 0.001. Reduced CI was defined as <3 L·min−1·(m2) −1.
Discordant Grading of Aortic Stenosis Severity: New Insights from an In Vitro Study
Published in Structural Heart, 2019
Jérôme Adda, Viktoria Stanova, Anne-Sophie Zenses, Marie-Annick Clavel, Paul Barragan, Guillaume Penaranda, Gilbert Habib, Philippe Pibarot, Régis Rieu
Doppler echocardiographic measurements were performed using a General Electric Vivid 7 (GE Health Medical, Horten, Norway), with a 3.5 MHz probe. The transvalvular flow velocities, MG, and aortic velocity-time integral (VTI) were measured five times per condition by continuous-wave Doppler. Transvalvular flow was measured using an electromagnetic flowmeter (Model 501, Carolina Medical Electronics Inc., East Bend, USA) positioned immediately below the prosthesis and averaged over 100 cycles. Valve EOA was determined by the continuity equation, by dividing the stroke volume measured with electromagnetic flowmeter by the echocardiographic aortic VTI. Mean transvalvular flow rate (Q) was calculated by dividing the SV by the LV ejection time measured on the Doppler acquisitions.
Transthoracic echocardiographic versus cardiometry derived indices in management of septic patients
Published in Egyptian Journal of Anaesthesia, 2020
Mohamed Elsayed Afandy, Sarah Ibrahim El Sharkawy, Amany Faheem Omara
Stroke volume (SV) was measured by multiplying the aortic valve area in the velocity-time integral of aortic blood flow (VTIAo) using the formula SV (ml) = (LVOTa) x (VTIAo). The aortic valve area was calculated from the measurement of the left ventricular outflow tract (LVOTd) measured at the insertion of the aortic cusp from the left para sternal axis view. The aortic valve area (LVOTa) was then calculated as π x (LVOTd/2)2, as the diameter of the aortic orifice is assumed to remain constant.