侵入性心肺运动试验诊断不明原因呼吸困难患者的病例分析

Diagnostic Application of Invasive Cardiopulmonary Exercise Test in Patients with Unexplained Dyspnea

目的探索侵入性心肺运动试验(invasive cardiopulmonary exercise test,iCPET)在不明原因呼吸困难患者病因诊断中的临床应用。方法回顾性分析在2017年5月5日-2020年10月1日间主诉劳力性呼吸困难的患者,对常规检查未查明原因的患者行右心导管检查,右心导管检查仍无法明确病因的患者进一步行iCPET。根据iCPET检查结果和诊断标准,将右心导管检查无明显异常、完成iCPET的患者分为4个亚组:运动诱发的肺动脉高压(eiPAH)组、运动诱发的射血分数保留的心力衰竭(eiHFpEF)组、前负荷衰竭组和氧化性肌病组。比较各亚组实验室检查,超声心动图、右心导管和iCPET运动峰值数据,描述iCPET检查诊断不明原因呼吸困难患者疾病分布情况和运动血流动力学特点。结果 1 046例劳力性呼吸困难患者中,常规检查确诊771例,剩余275例中131例(47.6%)经右心导管检查确诊,144例(52.4%)患者接受常规检查、右心导管检查后仍然病因不明。在这144例患者中,49例(34.0%)患者接受了iCPET检查,中位运动时间为375 s。共47例完成检查,男女比0.27∶1,平均年龄为(47.9±14.4)岁,其中20至59岁年龄段的患者占76.6%(36/47),78.7%(37/47)患者居住在城镇。前负荷衰竭组27例,表现为运动高峰右心房压力低;eiHFpEF组9例,表现为运动高峰肺毛细血管楔压过高;eiPAH组8例,表现为运动高峰平均肺动脉压过高;氧化性肌病组3例,表现为运动时组织摄取和/或利用氧气过程障碍。前负荷衰竭组、eiHFpEF组、eiPAH组3个亚组间比较,常规检查中,eiPAH组的血K+最高,前负荷衰竭组的血K+最低(P=0.014)。其余实验室检查在3个亚组间差异无统计学意义(P>0.05)。3个亚组的心功能分级均为世界卫生组织功能分级Ⅰ~Ⅱ级,心脏超声结构、右心导管检查结果均在正常范围,血气分析差异也无统计学意义(P>0.05)。3个亚组患者的iCPET检测结果显示,运动期间右心房压力增量差异有统计学意义(P=0.001),其中eiHFpEF组最高,前负荷衰竭组最低。结论本组右心导管检查无异常的不明原因呼吸困难患者的病因主要为前负荷衰竭,表现为运动高峰右心房压力低。iCPET对于右心导管检查无法提示病因的呼吸困难病例具有重要价值。

Objective To explore the clinical diagnostic application of invasive cardiopulmonary exercise test(iCPET)in patients with unexplained dyspnea.Methods A retrospective analysis was conducted,covering patients with a chief complaint of exertional dyspnea between May 5,2017 and October 1,2020.Right cardiac catheterization examination was performed on patients whose cause had not been identified through routine examination,and further iCPET was performed on patients if no clear etiology was identified through right cardiac catheterization.According to the results and the diagnostic criteria of iCPET,patients showing no obvious abnormalities in the right cardiac catheterization examination were divided into four subgroups:exercise-induced pulmonary arterial hypertension(eiPAH),exercise-induced heart failure with preserved ejection fraction(eiHFpEF),preload failure,and oxidative myopathy.By comparing the lab test,echocardiography,right heart catheter and iCPET peak exercise data of the subgroups,the disease distribution and exercise hemodynamic characteristics of patients with unexplained dyspnea examined by iCPET were described.Results Of the 1046 patients with exertional dyspnea,771 were diagnosed with routine examination,while among the remaining 275 patients,131(47.6%)were diagnosed with right cardiac catheterization and 144(52.4%)showed no clear etiology after routine examination and right cardiac catheterization.Of these 144 patients,49(34.0%)received iCPET with a median exercise time of 375 s.A total of 47 patients completed the examination,with a male-to-female ratio of 0.27∶1 and an average age of(47.9±14.4)years old.Among the 47 patients,76.6%(36/47)aged between 20 and 59 and 78.7%(36/47)lived in urban areas.The preload failure group(n=27)showed low right atrium pressure at peak exercise intensity.The eiHFpEF group(n=9)showed high wedge pressure of pulmonary capillaries at peak of exercise intensity.The eiPAH group(n=8)showed high average pulmonary artery pressure at peak exercise intensity.The oxidative myopathy group(n=3)was characterized by impairment of tissue uptake and/or utilization of oxygen during exercise.According to the comparison among the three subgroups of the preload failure,eiHFpEF and eiPAH,the eiPAH group had the highest blood K+level in routine examination,while the preload failure group had the lowest blood K+level(P=0.014).The iCPET of the three subgroups showed statistically significant(P=0.001)difference in right atrial pressure increase during exercise.Among the three,the eiHFpEF group had the highest increase and the preload failure group had the lowest increase.Conclusion In unexplained dyspnea patients showing no abnormal results in right cardiac catheterization examination,the main cause was preload failure,which manifested as low right atrial pressure at peak exercise intensity.The study showed that iCPET was of important value for dyspnea cases when the cause of the condition was not revealed with right cardiac catheterization.