A comparative study on modified right heart contrast echocardiography and traditional right heart contrast echocardiography

Objective To compare the safety, stability and effectiveness of modified right heart contrast echocardiography and traditional right heart contrast echocardiography in detection of intra- or extra-cardiac right to left shunt (RLS). Methods (1) Microscopic analysis: After agitating 10 times or 20 times (AS10, AS20, ASb10, ASb20), two right heart contrast agent (modified: 8 ml saline+ 1 ml blood+ 1 ml air; traditional: 9 ml saline+ 1 ml air) underwent the microscopic examination to compare the bubble size, bubble number and red blood cell morphology; (2) Clinical experiment: Thirty-two inpatients or outpatients suspected of RLS (cryptogenic stroke, transient ischemic attack, migraine with aura or platypnea-orthodeoxia syndrome) in Sichuan Provincial Hospital were selected. All patients underwent two right heart contrast echocardiography in which contrast agents had been agitated for 10 and 20 times (AS10, AS20, ASb10, ASb20). Monitor the right heart developing time, RLS and the oxygen saturation change were monitored and the RLS were semi-quantitatively analyzed. The indirect bilirubin and urobilinogen change after the contrast echocardiography were compared. Results Microscopic analysis showed that red blood cell membrane damaged more seriously as the agitated times increased. ASb20 generated more bubbles and the number of bubbles was about 4 times of that of AS10 generated (t=14.180, P<0.01); but the bubble size difference was not significant. With the modified method, RLS were detected in 22 patients (68.8%, 22/32). With the traditional method, RLS were detected in 18 patients (56.3%, 18/32). The results of semi-quantitative analysis of RLS was significant different between any two groups (ASb20 vs. AS10, AS20, ASb10: χ2=13.567, 11.646 and 9.001, respectively; ASb10 vs. AS10, AS20: χ2=9.125 and 2.589; AS20 vs. AS10: χ2= 8.127; all P<0.01). The change of oxygen saturation, the indirect bilirubin and urobilinogen were not significant after the contrast echocardiography. Conclusions Modified right heart contrast echocardiography is a safe, stable and cost-effective method to detect RLS. The semi-quantitative analysis of RLS with modified right heart contrast echocardiography and their relationship with clinical accident needs further research. Key words: Right heart contrast echocardiography; Microbubble; Right-to-left shunt; Patent foramen ovale