A computerized pharmaceutical intervention is shown to reduce reconciliation errors in the context of a high incidence of such errors.

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Introduction Continuity equation is the cornerstone of aortic valve area (AVA) calculation in patients with aortic stenosis (AS). In patients with irregular rhythms (IR) - especially atrial fibrillation (AF)-, values of velocity-time integral (VTI) at left ventricular outflow tract (LVOT) and aortic valve (AV) vary between heart beats. The usual recommendation is to average the measurements of 5 or 10 beats in both locations. However, original papers describing continuity equation, from which that recommendation arises (refs 1 & 2), only included 3 and 2 AF patients, respectively. To our knowledge, there are not clinical studies to support this procedure and its accuracy has not been established. In contrast, in a previous study our team had evaluated the accuracy of the double envelope technique to assess both LVOT and AV VTI in the same beat, with a 7.8% (CI 95%: 5.8–10.3) difference (error) in the estimation of AVA when compared to pulsed wave of LVOT in patients with stable sinus rhythm. Purpose To evaluate how dispersion in VTIs due to IR impacts on variability of AVA calculations. Methods For each patient, we recorded multiple measurements of VTI in both LVOT and AV (mean 36.8 beats, range 29–47) per patient and location). Reference AVA was estimated using the average of all these measurements. To estimate the accuracy of averaging 5 or 10 heart beats, we created a computer code which simulated the AVA calculation using random samples of these measurements, and calculated the difference between true AVA and that obtained in the simulation (expressed as percentage of the true value). The process was iterated 10,000 times to obtain the distribution of differences and to estimate its mean value. Data handling and graphic representation was performed with Python 3.9.6 and Pyodbc, Pandas, NumPy, Matplotlib and Seaborn libraries. Results We included data from 8 patients with AS and IR (Age: 71 to 89, mean 82.5 years; Aetiology: degenerative (100%); Sex: 3 males / 5 females; Rhythm: AF [7], atrial flutter [1]; Severity: severe [3], moderate [4], mild [1]). Mean difference in AVA calculations was 8.2% (range: 5.1–13.5%). With 10 beats, mean difference was 5.7% (range: 3.6–9.5%). Figute 1 shows violin plot with distribution in each patient of recorded VTIs at both AV (left) and LVOT (right). To ease visualization, data are expressed as percentage of mean values. Fig 2 shows how that variability results in inaccuracy of AVA calculations with 5 (left) or 10 beats (right). Note that in many cases, possible results are located on both sides of the severity threshold of 1 cm2 (red line). Conclusion AVA assessment using 5 beats average results in a mean difference (error) of 8.2%, which can be reduced to a mean of 5.7% using 10 beats. These differences are comparable with the previously observed with the double envelope technique (7.8%). Funding Acknowledgement Type of funding sources: None.

Introduction Visualization of a double envelope (DE) is a relatively common issue in aortic transvalvular continuous-wave Doppler (CW) traces. In 1997, Song et al proposed that velocity time integral (VTI) measured at the edge of the inner envelope (IE) might equal that of the left ventricular outflow tract (LVOT). This surrogate measurement would be especially interesting in patients with irregular heart rhythms, as both LVOT and valvular VTIs could be obtained from the same beat, thus avoiding inter-beat variability when assessing aortic valve area (AVA) with continuity equation. In contrast, based on clinical data and 3D-printed models, they raised concern that DE method in dome-shaped valves could lead to significant overestimation of LVOT velocities (about 40%). Later studies, including a Partner trial subanalysis, question the validity of this measurement. Purpose We created a computerized aortic valve model to reproduce the CW tracing, and analysed how valve morphology may lead to a valid, well defined inner envelope or, by contrast, produce overestimation of LVOT velocities. Methods The simulation code was created using Python (v3.9.6) along with NumPy and Matplotlib libraries. For each simulation, an aortic valve scheme was created (LVOT diameter: 2 cm; TSVI length: 1 cm; LVOT peak velocity 1.1 m/s; varying morphologies and lengths of the aortic cusps). The longitudinal axis between LVOT base and valve tip was divided in sections or levels (at least 300 per emulation). To recreate the CW trace, for each level, luminal diameter and peak velocity (according to continuity equation) were calculated, and an array of points was generated representing the aortic waveform during the entire systole. Slight random dispersion (standard deviation 0.05 times original values) was added to produce a more realistic image. Data points were represented as scatter plot over black background with transparency, simulating CW tracings (Figure 1) Results Figure 2 represents the plots of various aortic valve configurations (1st row AVA 1.6 cm2; 2nd: 1.2 cm2; 3rd: 0.8 cm2). Note that the innermost portion of the trace results in hollow space, as these velocities are produced in portions of ventricle and aorta which are not included in the simulation. Pink dashed line represents actual LVOT velocities. In a short-length flat valve (A), the IE is well defined and shows good correlation with LVOT velocity. In a cone-shaped 6mm length valve (B), there is a progressive brightness reduction, with no recognizable contour. With long (6 mm) dome-shaped valves, an ill-defined IE is produced at higher velocities than LVOT, which could result in overestimation. Conclusion DE method could accurately assess LVOT velocities when a sharp-defined IE is present and a dome-shaped valve can be excluded (e.g. rheumatic or some bicuspid valves). Measurements in a blurred DE or in a dome-shaped valve would produce overestimation of LVOT velocities and AVA. Funding Acknowledgement Type of funding sources: None.

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