Patent Ductus Arteriosus Revisited

To the Editor We offer the following comments regarding use of transesophageal and transthoracic echocardiography (TEE and TTE) in the management of patients with patent ductus arteriosus (PDA).1 First, and relating to the preferred method of diagnosis, the sensitivity of TEE is superior to that of TTE (98% vs 42%). The limitations imposed by the acoustic windows and the distance make TTE diagnosis in adolescents and adults difficult, if not impossible at times.2 Second, imaging of the left pulmonary artery is usually not necessary for the diagnosis of PDA. Multiplane TEE with color Doppler examination of the distal main pulmonary artery in midesophageal views is sensitive and obtainable in the majority of adults and adolescents.2–4 Furthermore, the mosaic of turbulent flow secondary to a PDA is directed preferentially toward the main pulmonary artery, not the left pulmonary artery.3 Third, although the saline-filled balloon positioned within the left main bronchus used in this case may improve TEE imaging of the PDA, the subsequent additional advice that “in select patients, visualization might be improved by filling the endotracheal cuff with normal saline to provide such a window” should be interpreted with caution, because it is the left bronchus rather than the trachea, that is more frequently interposed between the TEE transducer and the PDA. Song et al. used the technique described by Li et al.,5 calling for filling of an 8-cm segment of a glove positioned between the endotracheal tube and the carina with saline at the initiation of cardiopulmonary bypass. This technique was described to improve the imaging of structures anterior to the trachea (proximal aortic arch and innominate artery), but not a PDA. Filling the endotracheal cuff with saline will not improve the acoustic window because of interference by left bronchial and tracheal air. A conventional demonstration of a retrograde mosaic jet in the main pulmonary artery in midesophageal views is much safer and more effective. Fourth, current recommendations regarding PDA closure in adults are based on the demonstrated effects of a left-to-right shunt on pulmonary circulation and the history of infectious endarteritis.6 The authors did not calculate the shunt fraction, or demonstrate pulmonary hypertension and/or enlargement of the left heart chambers attributable to the PDA. The diameter and the length of a PDA do not predict shunt flow and its effect on pulmonary circulation because of varying ductal morphology and resistance to blood flow.7 The presence of a small jet in the pulmonary artery attributable to PDA is not an indication for PDA closure per se. Even if PDA closure were indicated, the treatment of choice in a young asymptomatic patient is transcatheter closure,7 and not an open surgical procedure with the utilization of cardiopulmonary bypass. Finally, the literature cited by the authors discusses infectious endocarditis and endarteritis, which are not relevant to the issue of marantic endocarditis at hand. Nonbacterial thrombotic endocarditis does not usually require surgical intervention but rather anticoagulation.8 Additionally, the averred link between the mortality from the PDA-related infectious endocarditis and preoperative antibiotic therapy is not supported by the cited article,9 attributing the declining risk of infectious endocarditis (not the mortality associated with it) to the general availability of antibiotics and changing economics, dental hygiene, and bacterial milieu.9,10 In conclusion, we recommend that further clarification of the echocardiographic diagnosis of PDA be included to support the decision to proceed with open-heart surgery in an asymptomatic 15-year-old patient with a PDA and nonbacterial thrombotic vegetations in the absence of significant hemodynamic effects. Edward Gologorsky, MD, FASE Anesthesiology Department Jackson Memorial Hospital/University of Miami Miami, Florida [email protected] Angela Gologorsky, MD Anesthesiology Department Memorial Regional Hospital East Hollywood, Florida Michael E. Barron, MD, FAHA Thomas A.