Analysis of aortic valve gradients by transseptal technique: Implications for noninvasive evaluation
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Abstract The peak instantaneous aortic valve gradient derived from Doppler echocardiography is commonly used to predict the severity of aortic stenosis. Peak instantaneous gradient should not be equated with the mean gradient or “peak to peak” gradient measured at cardiac catheterization. The primary purpose of this study is to assess the relationship between the aortic valve gradients, using a two‐catheter transseptal technique in 102 patients with aortic stenosis, mixed aortic stenosis and regurgitation, and following aortic valve replacement. These cases were drawn from a series of 111 consecutive transseptal procedures for patients with isolated aortic valve disease. No major complications occurred, and the most common reason for technical failure was inability to engage the atrial septum in postoperative patients. Although the peak instantaneous gradient correlates well with the mean gradient in aortic stenosis (r = .94, P < .001), mixed stenosis and regurgitation (r = .95, P < .001), and after aortic valve replacement (r = .86, P < .001), it systematically overestimates both the mean gradient and the peak to peak gradient. Neither the peak instantaneous nor the mean gradient correlates highly with aortic valve area in aortic stenosis (r = −.48, P < .01 peak; r = −.58, P < .001 mean gradient), mixed aortic stenosis and regurgitation (r = −.39, P NS peak; r = −.42, P NS mean gradient) or following aortic valve replacement (r = −.26, P NS peak; r = −.53, P < .01 mean gradient). Systolic time intervals also were analyzed from the simultaneous left ventricular and ascending aortic pressure tracings. The systolic ejection period, time to peak gradient, time to peak left ventricular pressure, and time to peak aortic pressure correlated poorly with aortic valve area. This study indicates that the mean gradient, which is consistently smaller than the peak instantaneous gradient, can be estimated by a simple regression formula: mean gradient = 0.70 peak instantaneous gradient. The mean gradient, which is usually less than the peak to peak gradient over 58 mm Hg and greater than the peak to peak gradient under 58 mm Hg, can be estimated by: mean gradient = 0.71 peak to peak gradient + 17 mm Hg. The limitations of isolated gradients in predicting aortic valve area indicate the importance of accurate flow measurements for optimal determination of the severity of aortic valve obstruction.Keywords:
Pressure gradient
Aortic pressure
Ventricular pressure
Cardiac catheterization
Pressure gradient
Aortic pressure
Ventricular pressure
Cardiac catheterization
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To evaluate the accuracy of Doppler echocardiography for measuring the interventricular pressure gradient in patients with ventricular septal defect (VSD), Doppler echocardiography and dual catheters were performed simultaneously in 31 cases with VSD ranging from 9 to 40 years old. The systolic jet velocities through VSD were recorded by the continuous-wave Doppler technique and converted to the peak instantaneous pressure gradient (delta Pp) and the mean pressure gradient (delta Pm) using a modified Bernoulli's equation with the aid of computer system. Both left and right heart catheters were performed to record the left (LVSP) and the right (RVSP) ventricular systolic pressure simultaneously. Guided by the color flow image Doppler technique, the tip of the right heart catheter was carefully placed within the jet area of the right ventricle. The following parameters were measured from the ventricular pressure curves, the peak instantaneous pressure gradient (IPG), the peak to peak pressure gradient (PPG) and the mean pressure gradient (MPG). The comparison between delta Pp and PPG yielded an excellent correlation (r = 0.99, SEE = 0.69 kPa). There was a close agreement between delta Pp and IPG (r = 0.99, SEE = 0.64 kPa). However, the correlation between delta Pm and MPG was also high (r = 0.98, SEE = 0.67 kPa). We conclude that Doppler echocardiography offers a reliable technique for measuring the interventricular pressure gradient in patients with VSD.
Pressure gradient
Ventricular pressure
Interventricular septum
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Surgical aortic valve replacement (SAVR) is the current treatment of choice for good surgical candidates with moderate to severe symptomatic aortic stenosis (AS). As transcatheter aortic valvular replacement (TAVR) has shown an improved one and two-year all-cause mortality, it has been chosen for moderately symptomatic severe AS patients. The purpose of this review was to perform a clinical comparison of TAVR vs. SAVR and to analyze the Health Index Factor (HIF) that makes TAVR a treatment of choice in asymptomatic AS patients. An extensive literature search of PubMed, Cochrane, and Embase databases was performed using the keywords “Aortic stenosis”, “SAVR”, “TAVR”, and “Asymptomatic”. A total of 45 prospective randomized clinical trials in the English language that were published from the year 2000 onwards were included in the final analysis. It has been found that 59.3% of asymptomatic AS patients are likely to die in the next five years without proactive treatment. Multiple studies have proven that early intervention with aortic valve replacement is superior to conservative treatment in severe asymptomatic AS; however, the choice between SAVR and TAVR is not well established. The NOTION Trial, SURTAVI Trail, and PARTNER 3 study have shown the non-inferiority of TAVR over SAVR, during one-year follow-up for low surgical risk patients. Evolut Low-Risk study and Early TAVR are the only two prospective studies performed to date that have enrolled patients with asymptomatic severe AS. The Evolut Trial demonstrated no difference in all-cause mortality at 30 days (1.3% vs. 4.8%. p=0.23), and 12 days (1.3% vs. 6.5%, p=0.11). Additionally, TAVR also decreases the risk of post-procedural atrial fibrillation, acute kidney injury (AKI), and rehospitalization, and leads to significant improvement in the mean trans-aortic pressure gradient. TAVR also showed marked improvement in the 30-day Quality of Life (QOL) index, where SAVR did not report any significant change in the QOL index. However, the official recommendations of Early TAVR are still awaited. TAVR has consistently shown a statistically non-significant difference in case mortality, risk of stroke, and rehospitalization with moderate to high surgical risk patients whereby recent initial trials have shown significant improvement in the QOL index and hemodynamic index for patients with asymptomatic disease. More extensive studies are required to prove the risk stratifications, long-term outcomes, and clinical characteristics that would make TAVR a preferred intervention in asymptomatic patients.
Valve replacement
valvular heart disease
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Valve replacement
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Valve replacement
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Objective: Aortic hemodynamics and wave reflections are independent predictors of adverse cardiovascular events. Surgical aortic valve replacement (SAVR) is still the first choice for treatment of patients with aortic stenosis. We sought to investigate in this pilot study the effect of SAVR upon aortic vascular function and hemodynamics. Design and method: Twenty-five patients (mean age 71.0 ± 7.1 years, 11 female) with severe aortic stenosis undergoing SAVR were included. Aortic hemodynamics and wave reflections (aortic pressures, aortic augmentation index [[email protected]], augmented pressure) and subendocardial viability ratio (SEVR) were measured with Sphygmocor. Measurements were conducted prior to the surgery and at discharge. Results: There was a statistically significant decrease in aortic systolic blood pressure (SBP) (134 ± 24 vs 118 ± 17mmHg with p = 0.002, respectively). that was not apparent in peripheral SBP. Diastolic blood pressure (both peripheral and aortic) did not change significantly, while heart rate was increased after the surgery (67 ± 11 vs 88 ± 15 bpm with p < 0.001, respectively). We observed a marginally significant decrease in aortic [email protected] (29 ± 13 vs 22 ± 12% with p = 0.05, respectively) and a decrease in aortic AIx (p < 0.001, Figure) and augmented pressure (20 ± 10 vs 8 ± 7 mmHg with p < 0.001, respectively). Moreover, there was a marginally non-significant trend for an increase in SEVR (137 ± 30 vs 149 ± 35%, p = 0.095). Conclusions: Our study shows that shortly after SAVR subjects show a decrease in aortic wave reflections with a small improvement of myocardial perfusion. These findings further elucidate the short-term hemodynamic consequences of SAVR.
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The ventricle function can be established by the vectorial description of left-ventricular pressure parameters or flow sizes, respectively. The vector diagrammes result from the momentaneous pressure within the ventricle on the X-axis and the differentiated pressure curve or the aortic flow, respectively, on the Y-axis. Well surveyable from the vector loop received (LVP/dp/dt) are established dp/dtmax, dp/dtmin, LVPmax, LVEDP as well as the tg of the pressure increase speed or the pressure decrease speed, respectively, pro developed pressure. By way of example medicamentous changes of the vector diagrammes were induced and the parameters mentioned established. The vectorial demonstration of the left-ventricular haemodynamics seems to give additional informations concerning the phase of centraction and relaxation
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Preload
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Although the transvalvular gradient is described as flow-dependent, pressure-dependence of the gradient, irrespective of flow, has not been demonstrated.The Sheffield pulse duplicator equipped with a X-Cell 21 porcine valve mounted in the aortic position was used. Transaortic gradient was measured at a constant rate of 80 beats/min, while flow was kept at 2, 5 or 8 l/min, and systemic pressure was increased up to 200 mmHg by adjusting peripheral resistance manually. Valve area was computed with the Gorlin formula. A total of 87 measurements was carried out.For each flow, transvalvular gradient increased linearly with pressure, and computed area decreased. The slope of the pressure-gradient relationship was independent of flow.Transaortic gradient depends not only on flow, but also shows pressure-dependency that should be taken into account when evaluating aortic stenosis, especially in hypertensive and hypotensive states.
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Pressure gradient
Peripheral resistance
Aortic pressure
Adverse pressure gradient
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If a method produces a pressure contour with an arbitrary relative amplitude and without a base line, i.e. a pressure tracing without scale, and another method gives two out of the following three values: peak; bottom; and mean pressures, then we can obtain a pressure contour with a specified pressure scale. We can also obtain the value of the derivative of pressure with respect to time. If the curve of the ascending aortic diameter change closely resembles the pressure contour at the same portion (assumption 1), we can obtain the aortic pressure contour with an arbitrary pressure scale measuring the aortic diameter by a non-invasive ultrasonic method. The aortic peak systolic, end-diastolic and mean pressures can be measured by other non-invasive methods. Therefore, we can specify the pressure scale of the contour, and obtain the maximum derivative of the aortic pressure. If the maximum derivative of the left ventricular pressure (max dp/dt) can be substituted by that of the aortic pressure (assumption 2), we can obtain the former (max dp/dt) by non-invasive measurements only. We confirmed assumptions 1 and 2 by animal experiments, and showed the feasibility of non-invasive measurements of the left ventricular max (dp/dt) by interpreting the aortic diameter change curve as the pressure contour.
Aortic pressure
Ventricular pressure
Derivative (finance)
Pressure measurement
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