To compare the effects of different right atrial pressurization methods on the detection of occult right to left shunt (RLS) of patent foramen ovale (PFO) by contrast transthoracic echocardiography (C-TTE), in order to improve the detection sensitivity of C-TTE.

A retrospective analysis was performed on 70 patients with PFO diagnosed by surgery or esophageal echocardiography at Sichuan Provincial People's Hospital from March 2019 to July 2020. All patients had negative C-TTE results in the resting state in the right heart. At the same time, all patients completed three right atrial pressurization methods: cough hard (CH), successful Valsalva maneuver (SVM), and SVM immediately followed by CH (SVM-CH). The effects of the three pressurization methods on the detection of RLS by SVM-CH were compared.

We applied three right atrial pressurization modes (CH, SVM-CH, SVM) and two combined modes (SVM and CH, SVM and SVM-CH) for C-TTE detection of PFO occult RLS. The detection rates were 71.43%, 95.71%, 81.43%, 97.14%, and 100%, respectively, and the detection rates for large RLS were 10.00%, 54.28%, 35.71%, 55.72%, and 71.43%, respectively. CH, SVM-CH, SVM, CH and SVM, SVM and SVM-CH were used for C-TTE, respectively, and the overall difference in the quantification of RLS was statistically significant (χ²=37.771, P＜0.001). Thirty-four of the 70 patients underwent transesophageal echocardiography (TEE). SVM and SVM-CH were used to increase the right atrial pressure for C-TTE, and the detection rate of occult RLS by C-TTE (100%, 34/34) was higher than that by TEE (82.35%, 28/34). Among the 34 patients, C-TTE was detected by SVM-CH, but not by SVM in three cases, all of which showed long fissure PFO on TEE.

Using SVM and SVM-CH to increase the right atrial pressure for C-TTE is helpful to improve the detection rate of PFO occult RLS by C-TTE, and the detection rate for PFO occult RLS by C-TTE combined with reasonable right atrial pressurization mode is better than TEE.