We have read with great interest the article of Sekma et al., demonstrating that the impact of sublingual administration of nitroglycerin on cardiac output was useful to diagnose heart failure in patients complaining of undifferentiated dyspnea at the emergency department.¹ We have several concerns that should improve their findings.

In their study, a decrease in cardiac output following nitroglycerin administration was greater in patients with preserved ejection fraction than those with reduced ejection fraction,¹ but the amount seems to be comparable between those with preserved ejection fraction and those without heart failure. It might be challenging to distinguish heart failure with preserved ejection fraction from non-heart failure diseases. Other data including plasma B-type natriuretic peptide might eventually be required for the definitive diagnosis of heart failure with preserved ejection fraction.

In their study, cardiac output seems to decrease following nitroglycerine administration in most heart failure patients. Cardiac output would rather increase in heart failure patients on the descending part of the Starling curve when their preload was reduced. Their finding might not be applicable to those with severe congestion.

It should be practical to more clarify the optimal timing to perform nitroglycerin test. In real-world daily practice, rapid surveillance to identify the etiology of dyspnea is required in the emergency department. Of note, transthoracic echocardiography is a powerful tool for such a purpose.² The nitroglycerin test seems to take over 10 minutes. It might be challenging to perform the test before echocardiography in the fear of diagnostic delay. Furthermore, the nitroglycerin test might be contraindicated for those with right ventricular infarction, hypertrophic obstructive cardiomyopathy, and severe aortic stenosis.³

我们饶有兴趣地阅读了 Sekma 等人的文章，该文章证明舌下含服硝酸甘油对心输出量的影响对于在急诊科主诉未分化呼吸困难的患者诊断心力衰竭很有用。¹我们有几个问题应该改进他们的发现。

在他们的研究中，射血分数保留的患者在给予硝酸甘油后心输出量的下降幅度大于射血分数下降的患者^1，但射血分数保留的患者与没有心力衰竭的患者之间的下降幅度似乎相当。区分射血分数保留的心力衰竭与非心力衰竭疾病可能具有挑战性。最终可能需要其他数据，包括血浆 B 型利钠肽，以明确诊断射血分数保留的心力衰竭。

在他们的研究中，大多数心力衰竭患者服用硝酸甘油后心输出量似乎下降。当他们的前负荷降低时，心力衰竭患者在 Starling 曲线的下降部分更愿意增加心输出量。他们的发现可能不适用于严重拥堵的人。

更明确进行硝酸甘油试验的最佳时机应该是切实可行的。在现实世界的日常实践中，急诊科需要快速监测以确定呼吸困难的病因。值得注意的是，经胸超声心动图是实现这一目的的强大工具。²硝酸甘油测试似乎需要 10 多分钟。由于担心诊断延迟，在超声心动图之前进行测试可能具有挑战性。此外，对于患有右心室梗塞、肥厚性梗阻性心肌病和严重主动脉瓣狭窄的患者，硝酸甘油试验可能是禁忌的。³