We would like to thank the editor for giving us the opportunity to respond to the issues raised in Hiroi et al. correspondence. We would also like to express our appreciation to Hiroi and his colleagues for their interest in our article and for their knowledgeable comments. Hiroi highlights important questions. The first was about the decrease in CO after NTG test which seems to be comparable between patients with preserved ejection fraction and those without HF. We agree with Hiroi that this finding could be challenging in the distinction between heart failure with preserved ejection fraction from non-heart failure diseases. Our results suggest that when NTG test is positive (unchanged CO) this means that heart failure is present and is most likely associated with reduced ejection fraction. This also means that when NTG test is normal (decrease of CO) additional investigations are needed including plasma B-type natriuretic peptide and echocardiography when available. Hiroi correctly noted that cardiac output seems to decrease following NTG administration in most heart failure patients in our study. These findings are in contradiction with studies suggesting that the failing human heart is unable to use the Frank–Starling mechanism. Although previous studies on human heart preparations have yielded conflicting results with regard to preload responsiveness of failing heart, it is accepted that in congestive heart failure, the ability of the heart to utilize the Frank–Starling mechanism is preserved but attenuated.³ It is likely that for some patients with end stage heart failure, cardiac output would increase in heart failure patients on the descending part of the Starling curve when their preload was reduced. This preload-CO relationship was documented in only few heart failure patients in our study. We believe that for this category of patients with obvious clinical symptoms of heart failure, the diagnostic challenge for the clinician is probably less important, and as such NTG test is probably not needed. Of course, the nitroglycerin test should not be used in patients with right ventricular infarction, hypertrophic obstructive cardiomyopathy, and severe aortic stenosis.² About the timing, NTG test should be performed as early as possible. This test is very simple and can be used in a few minutes. This could be helpful when echocardiography is not immediately available in the emergency room.

我们要感谢编辑给我们机会回应 Hiroi 等人提出的问题。一致。我们还要感谢 Hiroi 和他的同事对我们的文章的兴趣以及他们知识渊博的评论。Hiroi 强调了重要问题。第一个是关于 NTG 测试后 CO 的减少，这似乎在射血分数保留的患者和没有 HF 的患者之间具有可比性。我们同意 Hiroi 的观点，即这一发现在区分射血分数保留的心力衰竭与非心力衰竭疾病之间可能具有挑战性。我们的结果表明，当 NTG 测试呈阳性（CO 不变）时，这意味着存在心力衰竭，并且很可能与射血分数降低有关。这也意味着当 NTG 测试正常（CO 减少）时，需要进行额外的检查，包括血浆 B 型利钠肽和超声心动图（如果有）。Hiroi 正确地指出，在我们的研究中，大多数心力衰竭患者在使用 NTG 后心输出量似乎下降。这些发现与表明衰竭的人类心脏无法使用 Frank-Starling 机制的研究相矛盾。尽管先前对人类心脏制剂的研究在衰竭心脏的前负荷反应方面产生了相互矛盾的结果，但公认的是，在充血性心力衰竭中，心脏利用 Frank-Starling 机制的能力被保留但减弱。Hiroi 正确地指出，在我们的研究中，大多数心力衰竭患者在使用 NTG 后心输出量似乎下降。这些发现与表明衰竭的人类心脏无法使用 Frank-Starling 机制的研究相矛盾。尽管先前对人类心脏制剂的研究在衰竭心脏的前负荷反应方面产生了相互矛盾的结果，但公认的是，在充血性心力衰竭中，心脏利用 Frank-Starling 机制的能力被保留但减弱。Hiroi 正确地指出，在我们的研究中，大多数心力衰竭患者在使用 NTG 后心输出量似乎下降。这些发现与表明衰竭的人类心脏无法使用 Frank-Starling 机制的研究相矛盾。尽管先前对人类心脏制剂的研究在衰竭心脏的前负荷反应方面产生了相互矛盾的结果，但公认的是，在充血性心力衰竭中，心脏利用 Frank-Starling 机制的能力被保留但减弱。³对于一些终末期心力衰竭患者来说，当他们的前负荷降低时，心力衰竭患者的心输出量可能会在 Starling 曲线的下降部分增加。在我们的研究中，只有少数心力衰竭患者记录了这种前负荷-CO 关系。我们认为，对于具有明显心力衰竭临床症状的这类患者，临床医生的诊断挑战可能不那么重要，因此可能不需要 NTG 测试。当然，对于右心室梗塞、肥厚性梗阻性心肌病、严重主动脉瓣狭窄的患者，不宜使用硝酸甘油试验。²关于时机，应尽早进行NTG测试。这个测试非常简单，几分钟就可以使用。当急诊室无法立即进行超声心动图检查时，这可能会有所帮助。