Concealed pulmonary venous obstruction in right atrial isomerism with pulmonary outflow tract obstruction—surgical management following modified Blalock-Taussig shunt

Abstract

Obstruction to the pulmonary venous return is a frequent associated anomaly in patients with isomerism of the right atrial appendages. Yet, preoperative diagnosis by means of either cross-sectional echocardiography or cardiac catheterization can be intriguing. Indeed, the presence of two morphologically right lungs reduce considerably the size of window for precordial echocardiography. Also, in the presence of severe pulmonary stenosis or atresia, it can be difficult at cardiac catheterization to enter the pulmonary trunk. In these patients, construction of a systemicto-pulmonary artery anastomosis will almost inevitably result in pulmonary edema. Between May 1984 and December 1988, five patients with isomerism of the right atrial appendages, severely decreased pulmonary blood flow and concealed obstruction to the pulmonary venous return were admitted to our hospital. A modified BlalockTaussig shunt by interposition of a polytetrafluoroethylene prosthesis was performed in each patients and all of them developed pulmonary edema. Three patients died despite appropriate medical treatment. The remaining two patients were successfully treated by banding of the Blalock shunt. This was performed in the first patient at the time of the initial surgery, when prior to closure of chest, pulmonary edema became manifest. The second patient who developed pulmonary edema early postoperatively, underwent cardiac catheterization to confirm the clinical diagnosis of obstruction to the pulmonary venous return. Reduction of blood flow through the Blalock shunt with resolution of edema was initially achieved by means of a partially occluding balloon catheter. Pulmonary edema recurred one week later because of rupture of the balloon and the patient eventually underwent a successful banding of the Blalock shunt through a left thoracotomy. We conclude that preoperative assessment of the pulmonary venous return is mandatory in patients with right isomerism and reduced pulmonary blood flow. Construction of a modified Blalock-Taussig shunt in the presence of concealed obstruction to the pulmonary venous return will almost inevitably cause pulmonary edema. Banding of the Blalock shunt can be successful, as observed in our experience, for the management of this serious complication.

“Masked” pulmonary venous obstruction in patients with isomerism of the right atrial appendages: an overstated association

“…"Masking" of pulmonary venous obstruction has been reported in the setting of right isomerism, with resultant pulmonary edema after augmentation of the flow of blood to the lungs. 5,6,9,10 Freedom and colleagues have stated "All too frequently, construction of a systemic to pulmonary artery anastomosis unmasks 'silent' obstructed total anomalous pulmonary venous connections." 10 In our series, 4 of 19 patients with pulmonary venous obstruction inappropriately received augmentation of pulmonary blood flow without relief of pulmonary venous obstruction, with resultant pulmonary edema.…”

“…"Masking" of pulmonary venous obstruction is very rare. The frequent "unmasking" reported after infusions of prostaglandin E 1 , 10 or construction of systemic-to-pulmonary arterial shunts 5,6,9 probably reflects publication bias of reports with a "cautionary tale." Furthermore, careful evaluation of clinical findings and chest radiography at presentation suggest that the use of the term "unmasking" can be misleading, since in all of our cases there were clear indicators of pulmonary venous obstruction prior to augmentation of pulmonary blood flow.…”

“…3,5,6 In the setting of decreased pulmonary blood flow, such obstruction of pulmonary venous return may be "masked". Several authors have reported cases of "unmasking" of the obstruction following construction of a systemic-to-pulmonary shunt, [5][6][7][8][9] or after infusion of prostaglandin E 1 . 10 Freedom and colleagues stated that "All too frequently, construction of a systemic to pulmonary artery anastomosis unmasks 'silent' obstructed total anomalous pulmonary venous connections, which are not uncommon in these patients, resulting in intractable pulmonary edema and death."…”

Hearts with isomerism of the right atrial appendages – one of the worst forms of disease in 2005

“…When there is important obstruction to pulmonary venous flow, the severe reduction in the rate of flow may mask the clinical importance of the pulmonary venous anomaly. [139][140][141] So as to combat this potential problem, we devised the prostaglandin challenge 141 in the era before the routine application of cross-sectional echocardiographic imaging. The test was designed to augment pulmonary blood flow in order to unmask any concealed pulmonary venous obstruction.…”