Case report
We present the case of a 38-year old Brazilian man who presented with a
4-day history of chest pain radiating to his abdomen and back. He was
subsequently diagnosed with an extensive Stanford type B aortic
dissection originating at the base of the left subclavian artery with
extension into the iliac arteries. With the exception of the left renal
artery, all visceral branches were supplied by the true lumen. He was
managed conservatively with strict blood pressure control and discharged
home. On serial CT aortogram 8 weeks later, the dissection appeared
stable, however, the diameter of the distal thoracic descending aorta
had increased to 64mm from 59mm. His aortic arch was deemed to be
unsuitable for stent grafting due to the acute angle from the arch (60
degree angulation) into the aneurysm, resulting in a Gothic arch; and he
was planned for open surgical repair.
A further 3 months later, prior to planned repair, the patient presented
with severe left sided chest pain. A repeat CT aortogram demonstrated a
fusiform dilatation of the distal arch and descending thoracic aorta
measuring 73x 69mm wide (Figure 1) with interval dilation of the false
lumen. The decision was made to proceed with an open thoracoabdominal
aortic aneurysm (TAAA) repair utilising cardiopulmonary bypass with deep
hypothermic circulatory arrest. A pre-operative cerebrospinal drain was
placed to decrease the risk of spinal ischaemia throughout the
operation. The patient was positioned in the left lateral position with
a thoracoabdominal incision made through the fifth intercostal space.
Retroperitoneal dissection revealed vessels of good calibre and an
extensive TAAA particularly in the upper thorax (Figure 2). Peripheral
cardiopulmonary bypass was instituted via the left femoral artery and
vein utilising an 8mm Dacron graft and Y connector, and a 25Fr venous
cannula respectively. The patient was cooled to 18 degrees Celsius and
placed in Trendelenburg positioning for clamping of the mid thoracic
aorta.
The aneurysm was incised and the dissection flap unroofed with a 2cm
cuff created for the proximal anastomosis using a 26mm Dacron graft.
Arterial inflow was established via an 8mm sidearm, with clamping of the
femoral line and subsequent deairing of the cerebral circulation and
rewarming of the patient. The Dacron graft was then clamped proximal to
the arterial inflow and femoral bypass reinstated with the clamp moved
to just above the diaphragm. Multiple small intercostal arteries were
oversewn, with two large intercostals at T10 controlled with Fogarty
catheters and anastomosed utilising separate 8mm Dacron grafts. The
cross clamp was moved to just above the renal arteries, allowing a
Carrel patch containing the coeliac trunk and superior mesenteric
arteries to be fashioned. Continuous perfusion to the superior
mesenteric artery was provided via a 12Fr cannula. The femoral inflow
was clamped, and the abdominal aortic clamp removed, with fenestration
of the aorta to ensure the left femoral artery was supplied by the true
lumen. A size 28mm Dacron graft was anastomosed to the suprarenal aorta,
a clamp placed superior to the suture line, and femoral inflow restored.
The Carrel patch containing coeliac trunk and superior mesenteric
vessels was anastomosed to the anterior aspect of the graft.
The graft was positioned through the aortic opening in the diaphragm and
the 8mm Dacron graft supplying the intercostals anastomosed towards the
posterolateral side of the graft. The 26mm and 28mm Dacron grafts were
anastomosed in the mid thoracic aorta with deairing and clamping of
femoral inflow. The patient was weaned from bypass without difficulty
and the venous line removed with repair of the femoral vein. The femoral
and thoracic 8mm Dacron inflow grafts were ligated and divided, with
repair of the diaphragm and costal margins undertaken. The bypass time
was 312 minutes and upper body circulatory arrest time 39 minutes. He
was transferred to intensive care in a stable condition with systolic
blood pressure targets of 90-100mmHg. His immediate post-operative
course was complicated by vasoplegia, requiring noradrenaline, and
coagulopathy requiring massive transfusion.
The patient was initially agitated and unable to obey commands. He
became febrile on day 6 post-operatively and was diagnosed with a
ventilator acquired pneumonia and commenced on tazocin and vancomycin.
He was extubated on day 8 with improvement in neurology, however,
required reintubation due to respiratory distress later that day. He
remained febrile, with surgical wound dehiscence and escalation of his
antibiotics to meropenem and vancomycin. Despite adequate treatment of
his pneumonia, with successful extubation on day 10, and wound
dehiscence with antibiotics and surgical debridement, the patient had
persistent tachycardia up to 180bpm without haemodynamic compromise.
Post-operative transthoracic echocardiography revealed moderate global
impairment with trivial pericardial effusion. Postural telemetry (Figure
3), demonstrated a sitting heart rate of 101bpm which increased to
144bpm on standing and 164bpm on mobilisation without incrementation of
the blood pressure (110/54mmHg sitting to 100/67mmHg standing),
consistent with POTS. The patient was commenced on metoprolol,
fludrocortisone and ivabradine with improvement in his tachycardia. He
received multiple blood transfusions to increase his haemoglobin from 90
to 110g/L. He was discharged home 6 weeks after his operation with no
disability.