c-TTE and c-TEE with “Curtain effect” for detecting right-to-left shunt in patients with cryptogenic stroke

This study compares right heart contrast transthoracic echocardiography (c-TTE) and contrast transesophageal echocardiography (c-TEE) at different states for detecting and grading the right-to-left shunt (RLS) in patients with cryptogenic stroke (CS). A total of 150 CS patients were enrolled. All patients underwent c-TTE and c-TEE at 3 different states: the Rest, the Valsalva Maneuver, and the state of rest shortly after the Valsalva Maneuver (referred to as "Curtain effect"). Right-to-left shunt due to patent foramen ovale (PFO-RLS) or pulmonary right-to-left shunt was identified by the microbubble characteristics in the left atrium. The detection rates and semiquantitative grades of RLS were compared between c-TTE and c-TEE under different states. c-TTE at Valsalva Maneuver detected more RLS than c-TEE (83.3% vs 65.3%, P < .05). c-TTE at "Curtain effect" revealed more PFO-RLS and higher grades of PFO-RLS than c-TTE at Rest (91.8% vs 72.7%, P < .05). c-TTE showed higher grades of PFO-RLS compared to c-TEE at any state (P < .05). c-TTE at Valsalva Maneuver or "Curtain effect" has superiority in detecting RLS and grading PFO-RLS compared to c-TEE; it can be a practical screening approach for suspected RLS in CS patients.