CASE REPORT
We report a case of a 61-year-old woman with worsening dyspnea and
history of an ALCAPA (Anomalous Left Coronary Artery from Pulmonary
Artery) syndrome having undergone coronary artery bypass grafting
(saphenous venous graft to left anterior descending artery) 30 years
before. Transesophageal echocardiography revealed severe mitral
regurgitation. Coronary angiography and computed tomography showed
patency of the graft, with the dilated vein running across the front of
the ascending aorta and being responsible for the perfusion of the left
anterior descending and circumflex arteries. (Figure 1). In order to
avoid injuring the graft, we performed the mitral valve replacement
(MVR) through a right minithoracotomy approach under ventricular
fibrillation (VF) without aortic cross clamping.
SURGICAL TECHNIQUE
A double lumen endotracheal tube was used for intubation and
transesophageal echocardiography was placed for cardiac monitoring. The
chest was opened through a right minithoracotomy (skin incision ≤ 7 cm)
under one lung ventilation at the 4th anterolateral intercostal space.
The endoscopic port was placed at the right 3rd anterior intercostal
space and used as a CO2 port. Cardiopulmonary bypass was instituted
through peripheral cannulation (right femoral artery and vein) using
vacuum-assisted venous drainage. After cooling to 22°C in order to
induce VF, a left atriotomy between the phrenic nerve and pulmonary
veins was performed. MVR was performed in standard fashion using
instruments for minimally invasive mitral surgery. After a prosthetic
biologic St Jude #33 valve was sewn into place
(Figure 2), the left atriotomy was closed with slow filling and
de-airing. When rewarming was completed, cardioversion was performed.
After recovery to sinus rhythm, cardiopulmonary bypass was terminated
and the femoral cannulas removed. A right pleural chest tube was
positioned, and the incision was closed.
No intraoperative complications were registered. The patient had good
in-hospital progression and discharge on postoperative day seven.
DISCUSSION
Conventional re-operative MVR by median sternotomy has several
challenges as it requires dissection to the apex, aortic clamp and
myocardial protection. [1-2] In the presence of adhesions, this
approach carries increased risk of injury of major cardiac structures
(right ventricle, innominate vein and bypassed grafts). [1-2] This
case revealed a very dilated vein running close to the sternum and
across the front of the ascending aorta. (Figure 1) These anatomical
proximities and the fact that this graft is responsible for the
perfusion of all left coronary territory, are high predictive factors of
surgical risk and mortality in a re-sternotomy.
Minimally invasive mitral surgery is associated with a mortality rate
similar to that for sternotomy but reduced length of intensive care unit
and hospital stays, fewer blood transfusions, earlier recovery of daily
activities and improved quality of life. [1-2] The right
minithoracotomy approach can achieve an excellent operative view of the
mitral valve without requiring dissection of adhesions and has
demonstrated to be safe and with similar results to re-sternotomy.
[1-2] By performing the procedure under VF with systemic
hypothermia, aortic cross-clamping and interruption of the graft flow is
unnecessary, not necessarily compromising myocardial protection, thus,
avoiding dangerous dissection around the aorta and the dilated patent
graft. [1-2] Even though myocardial protection can still be a
concern to surgeons, the safety of MVR under VF has been documented in
these particular cases of functioning grafts. [3] Excluding cases of
aortic insufficiency, which can make this technique unfeasible because
of retrograde flow obstructing the operative field, when comparing to
MVR with cardioplegic arrest, the efficiency and safety of this method
is also reported. [1-3]
Current knowledge and the success of our case suggest that reoperative
MVR under VF without aorta cross clamping through a right
minithoracotomy is a safe, reproducible and effective option for
patients requiring redo mitral valve surgery, especially when presenting
anatomical characteristics that increase the risk of re-sternotomy such
as coronary bypass grafts.
Figure 1 – Computed tomography and coronary angiography showing the
dilated patent coronary graft (saphenous vein to left anterior
descending artery).