Clinical Characteristics And Pathogenesis Of Cryptogenic Stroke With Right-to-Left Shunt

Objective:Patent foramen ovale(PFO)is closely associated with cryptogenic stroke(CS),but its pathogenesis remains unclear.In this study,contrast-enhanced transcranial Doppler(c-TCD)ultrasound was used to examine whether there was right-to-left shunt(RLS)in patients with CS.To compare the clinical characteristics,vascular risk factors,platelet function,coagulation function and the structural and functional characteristics of the heart in CS patients with RLS,and to explore the pathogenesis of RLS related CS and the influence of the shunt size of RLS is of great significance to the diagnosis,prevention,treatment and prognosis of ischemic stroke.Methods:Patients admitted to the Department of Neurology in our hospital between October2018 and September 2020 were selected according to the International Trial of Org 10172 in Acute Stroke Treatment(TOAST),183 patients classified as CS were included in this study.All patients underwent c-TCD,laboratory and cardiac ultrasonography examination.According to the existence of RLS,divided into RLS positive(RLS+)group and RLS negative(RLS-)group.According to the size of RLS shunt volume,the RLS+ group was further divided into small shunt group(≤ 25 microemboli signals)and large shunt group(>25 microemboli signals or forming a “rain screen”).There were 90 patients(49.2%)in the RLS+ group,93 in the RLS-group(50.8%),43(47.8%)in the small shunt group,and47(52.2%)in the large shunt group.Demographic characteristics,cerebrovascular disease risk factors,platelet and coagulation function,cardiac structure and function of the patients were collected to compared the influence of shunt and shunt size.All statistical analysis were performed in SPSS 25.0 software.Results:(1)Comparison of risk factors: compared with the RLS-group,patients in the RLS+group had lower rates of smoking and diabetes history(P<0.05),and high rates of migraine,stroke or transient ischemic attack(TIA)and deep venous thrombosis of the lower extremity(P<0.05).There were no significant differences in age,gender,body mass index,drinking,hypertension and hyperlipidemia between the two groups(P>0.05).(2)Platelet function and coagulation function: Compared with RLS-group,mean platelet volume and D-dimer content in the RLS+ group were higher(P<0.05).However,there were no significant differences in the number of platelets,C-reactive protein,prothrombin time,activated partial thromboplastin time,thrombin time and fibrinogen(P>0.05).(3)Cardiac structure and function: Compared with the RLS-group,the left atrial anteroposterior diameter and pulmonary artery systolic pressure in the RLS+ group were higher(P<0.05).There were no significant differences in left ventricular end-diastolic diameter,left ventricular end-systolic diameter,interventricular septal thickness,left ventricular posterior wall thickness and left ventricular ejection fraction(P>0.05).(4)Comparison of shunt degree: Compared with the small shunt group,the mean platelet volume,D-dimer content and left atrial diameter in the large shunt group were higher(P<0.05).The other indexes had no significant differences(P>0.05).Conclusion:Our results suggest that the pathogenesis of RLS related CS patients is not related to atherosclerosis but more likely to be related to paradoxical embolism.The size of the RLS is related to the occurrence of stroke,and the large shunt group had larger mean platelet volume,higher D-dimer content,and larger left atrial diameter.The pathogenesis of RLS associated CS may be related to platelet activation,hypercoagulability and left atrial enlargement.