*2.2.1 Bidirectional Glenn procedure (cavopulmonary anastomosis)*

Bidirectional cavopulmonary anastomosis is a modified version of classic Glenn procedure in which the upper end of the divided SVC is anastomosed end to side to the right PA without disconnecting the latter from the main PA. Thus, the SVC blood is diverted into both the right and left PAs, justifying the term, "bidirectional."

Experimental bidirectional cavopulmonary anastomosis was first studied by Haller et al. [11] in animal models, and its first clinical use was described by Azzolina et al. [12] in 1972. Other investigators [13–17] later applied this technique to palliate complex heart defects with decreased pulmonary blood flow. Hemodynamic advantages of the bidirectional Glenn procedure are improvement of effective pulmonary blood flow, decrease in total pulmonary blood flow, and reduction of left ventricular volume overloading. In addition, preservation of continuity of the pulmonary artery is an added advantage and may help facilitate a low-risk Fontan procedure. When both right and left SVCs are present, bilateral bidirectional Glenn shunts should be performed, especially if the bridging innominate vein is absent or small. Based on our own experience and that published in the literature [13–17], the author recommended serious consideration in employing bidirectional cavopulmonary anastomosis as an interim palliative procedure for patients who are at an increased risk for the Fontan procedure [9, 10].
