Department of Cardiology, University Hospital, Bern, Switzerland.
Department of Cardiology, University Hospital, Bern, Switzerland.
J Am Soc Echocardiogr. 2022 Nov;35(11):1123-1132. doi: 10.1016/j.echo.2022.07.005. Epub 2022 Jul 19.
Dobutamine stress echocardiography is used to increase transvalvular flow in patients with low-flow, low-gradient aortic stenosis (AS). Dobutamine fails to increase the stroke volume index (SVI) in one third of patients. The aim of this study was to test whether passive leg raise (PLR) added to dobutamine could increase SVI and transvalvular flow in patients with severe paradoxical low-flow, low-gradient AS.
Forty-five patients with apparent severe low-flow, low-gradient AS on the basis of traditional measurements were included. Twenty-five were categorized as belonging to the paradox group (left ventricular ejection fraction [EF] ≥ 50%) and 20 to the low EF group (left ventricular EF < 50% or "classical" low-flow, low-gradient AS) for comparison. A four-step stress echocardiographic examination was performed: resting conditions (rest), PLR alone (PLR), maximal dobutamine infusion rate (Dmax), and a combination of Dmax and PLR (Dmax+PLR). Aortic valve area, SVI, and mean transvalvular flow were calculated using both the velocity-time integral (VTI) of left ventricular outflow tract and the Simpson method. Changes compared with rest and between the stress maneuvers were analyzed.
In the paradox group, compared with rest, left ventricular end-diastolic volume was significantly decreased with Dmax but was completely restored with Dmax+PLR (rest vs Dmax vs Dmax+PLR: 61 ± 15 vs 49 ± 18 mL [P < .001] vs 61 ± 18 mL [P = NS]). The smallest increase in SVI in the paradox group was observed during Dmax (PLR vs Dmax vs Dmax+PLR: VTI, 38 ± 4 mL/m [P < .001] vs 36 ± 7 mL/m [P = .019] vs 41 ± 7 mL/m [P < .001]; Simpson, 28 ± 6 mL/m [P < .001], 21 ± 7 mL/m [P = NS], 27 ± 7 mL/m [P = NS]). Compared with Dmax, Dmax+PLR was able to achieve a higher SVI (VTI, 36 ± 7 vs 41 ± 7 mL/m [P < .001]; Simpson, 21 ± 7 vs 27 ± 7 mL/m [P < .001]) and transvalvular flow with the Simpson method only (179 ± 56 vs 219 ± 56 mL/sec, P < .001), as well as a higher mean gradient (34 ± 10 vs 39 ± 12 mm Hg, P = .003) and AVA with the Simpson method (0.64 ± 0.21 vs 0.73 ± 0.21 cm, P = .026). In the low EF group, only SVI VTI (31 ± 8 vs 35 ± 7 mL/m, P = .034) and mean gradient (29 ± 12 vs 34 ± 14 mm Hg, P = .003) were higher with Dmax+PLR. The proportion of patients with SVI VTI ≥ 35 mL/m and increases of SVI VTI of >20% compared with rest was highest with Dmax+PLR in both groups.
Dobutamine decreases preload in paradoxical low-flow, low-gradient AS. Adding PLR counteracts this effect, resulting in increased SVI and flow (in one method). The combined stress maneuver allowed reclassification of some patients from severe to moderate AS and may therefore be useful in selected cases in this population in which severity is uncertain.
多巴酚丁胺负荷超声心动图用于增加低流量、低梯度主动脉瓣狭窄（AS）患者的跨瓣流量。三分之一的患者多巴酚丁胺不能增加每搏量指数（SVI）。本研究的目的是测试被动抬腿（PLR）是否可以增加严重矛盾性低流量、低梯度 AS 患者的 SVI 和跨瓣流量。
纳入 45 名基于传统测量的严重低流量、低梯度 AS 患者。25 例被归类为悖论组（左心室射血分数[EF]≥50%），20 例为低 EF 组（左心室 EF<50%或“经典”低流量、低梯度 AS）进行比较。进行了四个步骤的超声心动图检查：休息状态（休息）、单独 PLR（PLR）、最大多巴酚丁胺输注率（Dmax）和 Dmax+PLR 的组合（Dmax+PLR）。使用左心室流出道速度时间积分（VTI）和 Simpson 方法计算主动脉瓣面积、SVI 和平均跨瓣流量。分析与休息相比的变化和应激动作之间的变化。
在悖论组中，与休息相比，左心室舒张末期容积在 Dmax 时显著降低，但在 Dmax+PLR 时完全恢复（休息与 Dmax 与 Dmax+PLR：61±15 与 49±18 mL [P<0.001] 与 61±18 mL [P=NS]）。悖论组 SVI 的最小增加发生在 Dmax 期间（PLR 与 Dmax 与 Dmax+PLR：VTI，38±4 mL/m [P<0.001] 与 36±7 mL/m [P=0.019] 与 41±7 mL/m [P<0.001]；Simpson，28±6 mL/m [P<0.001]，21±7 mL/m [P=NS]，27±7 mL/m [P=NS]）。与 Dmax 相比，Dmax+PLR 能够实现更高的 SVI（VTI，36±7 与 41±7 mL/m [P<0.001]；Simpson，21±7 与 27±7 mL/m [P<0.001]）和 Simpson 方法的跨瓣流量（179±56 与 219±56 mL/sec，P<0.001），以及更高的平均梯度（34±10 与 39±12 mmHg，P=0.003）和 Simpson 方法的 AVA（0.64±0.21 与 0.73±0.21 cm，P=0.026）。在低 EF 组中，只有 SVI VTI（31±8 与 35±7 mL/m，P=0.034）和平均梯度（29±12 与 34±14 mmHg，P=0.003）在 Dmax+PLR 时更高。在两组中，SVI VTI≥35 mL/m 和 SVI VTI 增加>20%的患者比例在 Dmax+PLR 时最高。
多巴酚丁胺降低矛盾性低流量、低梯度 AS 的前负荷。PLR 的添加可抵消这种作用，从而增加 SVI 和流量（在一种方法中）。联合应激动作可以重新分类一些严重程度不确定的患者为中度 AS，因此在该人群中可能有用。
