Glenn Operation – Superior Bidirectional Cavopulmonary Anastomosis

Definition

The bidirectional Glenn operation (anastomosis of the superior caval vein to the right pulmonary artery) is indicated in several different heart defects. It is common to them that biventricular correction is not possible due to hypoplasia of a ventricle. It can be part of partial correction (so-called one-and-a-half ventricle repair) or a step towards separation of the pulmonary and systemic circulation (Fontan operation). Indication: in third to sixth month of life to reduce volume strain of the heart and avoid shunt complications. 

Dignosis

  • by echocardiography: function of the chambers and of the tricuspid, mitral and aortic valve. Gradient across the possibly reconstructed aortic arch. Unobstructed interatrial septum and  pulmonary venous inflow
  • by heart catheterization: pulmonary artery vessel bed developed? Desirable parameters are a total lower lobe index >120±30mm²/m², transpulmonary gradient [TPG] = diastolic PA pressure diastolic – LA mean <12 mmHg, with EDP <12 mmHg; PVR < 4 Wood units. Hemodynamics: patients with low enddiastolic chamber pressures who have good oxygen saturation (75-85%) will tolerate the Fontan circulation well, even with borderline PA size. Aortic arch: morphology/pressure gradients across the aortic arch --> if necessary, intervention with or without stent implantation
  • Magnetic resonance imaging (MRI): alternatively to heart catheterization, if the hemodynamics is good (good oxygen saturation, good ventricular function in echocardiography), the morphology of the pulmonary arteries and the aortic arch can be evaluated by MRI

Operation

Bidirektionale Glenn- Operation

In the bidirectional Glenn operation the heart-lung machine is used in normothermia and with the heart beating. The superior  caval vein is detached from the right atrium. The stump on the atrial side is oversewn and, after mobilization of the pulmonary arteries, a further anastomosis is created between the superior  caval vein and the pulmonary arteries. At the DHZB the Glenn operation is preferred to the hemi-Fontan operation. In the hemi-Fontan operation the stump of the superior caval vein on the atrial side is not transected after incision and is not oversewn.. Instead, the continuity of the superior caval vein remains and an intra-atrial GORE-TEX® membrane is placed to interrupt the continuity created between the right atrium and the right pulmonary artery; this GORE-TEX®  membrane is later removed during the (intracardiac) Fontan operation.