Operation:
Our surgical approach was as previously described.1 We
positioned the patient supine with a bump underneath the left shoulder
blade to elevate the left hemithorax and extend the neck. Double lumen
endotracheal intubation was used to achieve left lung isolation and a
transesophageal echocardiography (TEE) probe was placed. A 5cm
parasternal anterior thoracotomy was made in the third intercostal space
(Image 2). Two inches of subcutaneous fat made visualization difficult.
A mini-mitral retractor (Estech, AtriCure Corporate Headquarters 7555
Innovation Way Mason, OH 45040 USA) was used to facilitate exposure. The
pericardium overlying the right ventricular outflow tract was identified
and opened in parallel direction to the Right Ventricular Outflow
Tract–Pulmonary Artery. Traction sutures were applied to the edges of
the incised pericardium.
With this exposure, we realized that our incision was too inferior, in
that the right ventricle was preferentially exposed rather than the body
of PA (Image 3). In hindsight a second intercostal space incision would
have been better for isolation of the main PA. In order to better
facilitate exposure, we placed a simple retraction suture in the main PA
to pull it inferior. We were also prepared to resect a portion of the
second rib, but such was not required.
The right common femoral vein and artery were exposed in a standard
fashion. The patient was fully heparinized and cannulation of the common
femoral vein (wire-guided 25-French Medtronic venous cannula extending
into the right atrium verified by transesophageal echocardiography) and
artery (wire-guided 18-French Femoral-Flex cannula ) was accomplished.
Due to the deep layer of subcutaneous fat encountered, we decided to
tunnel the cannuli through separate stab incisions. This facilitated the
insertion of needle and guide wire into target vessels followed by
dilation of each vessel and proper TEE guided placement of wires and
cannuli with minimal line kinking and enhanced ergonomics (Image 4).
Once the ACT (Activated Clotting Time) was confirmed to have reached
above 400 seconds, cardiopulmonary bypass (CPB) was initiated. At that
point, a one-inch incision was made in the main pulmonary artery in
order to insert ring forceps and extract the clots. Although full
cardiopulmonary bypass with approximately 5 L/min was ongoing, bleeding
from the PA incision was significant making visualization difficult thus
requiring simultaneous suctioning through the limited surgical incision
in order to identify the clots. Nevertheless, with vigorous suctioning
employed to clear the main PA, we were able to identify two large clots,
grasp each with endoscopic-type ring forceps and extract the target
clots each measuring about 8 inches (Image 5), from the right and left
pulmonary trunks.
Further investigation and review of the intraoperative TEE images
revealed that the venous cannula had slipped back toward the right
atrial (RA)-IVC junction rather than being high up in the mid RA, thus
leaving volume undrained and the right ventricle relatively full.
Furthermore, we suspected that the flow of 5 L/min was not adequate to
empty the heart in this large patient with BMI of 44 who had evidence of
fluid overload based on preoperative echocardiography and CT scan. With
this in mind, we should have deployed dual venous cannulas (placed via
the common femoral vein into the RA and a second percutaneously placed
superior vena cave (SVC) cannula inserted under TEE guidance via the
right internal jugular vein). We believe dual percutaneous cannulation
and confirmation of accurate position by TEE is advisable in large
patients and would prevent this undue hardship of exposure and clot
retrieval.
Once the two large clots were extracted, the pulmonary arteriotomy was
closed with multiple pledgetted 3-0 prolene stitches, instead of the
usual running two-layer closure. This technique facilitated repair of
the pulmonary artery while applying suction to clear the bleeding from
the surgical site, given inadequate venous drainage.
The patient was then weaned off cardiopulmonary bypass without
difficulty. Cardiac function was assessed via TEE and the right
ventricle remained dilated however function had improved to only mildly
depressed systolic function (compared with severely depressed systolic
function pre-operatively). Hemostasis was ensured and two chest tubes
were placed through separate entry points into the fourth intercostal
space. The anterior thoracotomy was closed in standard fashion and
decannulation followed by repair of femoral vessels with resultant
excellent distal pulses in the femoral artery.
In a follow-up case, and after learning from the aforementioned
experience, we modified our technical approach by making the anterior
thoracotomy incision in the second intercostal space, inserting a second
percutaneous cannula in the SVC, and placing a 2 cm purse-string suture
about the pulmonary arteriotomy prior to incision which was sufficient
to seal the pulmonary artery entry point at the end of the procedure.
Post-operative course :
Aerosolized Epoprostenol Sodium (Flolan) was initiated in the operating
room prior to transport to the ICU to support right ventricular
function. The patient required inotropic and ventilatory support until
post-operative day (POD) 3 at which point he was extubated. Flolan was
weaned based on a combination of central venous gas oxygen saturation,
central venous pressure and echocardiographic assessment of RV function
given absence of a PA catheter to assess right heart function. Notably,
the patient had a known left femoral DVT pre-operatively, and an IVC
filter was placed on POD 3 as a safeguard for further pulmonary
embolism. His hospital course was further complicated by
thrombocytopenia and non-oliguric acute kidney injury with coinciding
hyperkalemia, requiring one session of hemodialysis. Given exposure to
heparin, a heparin-induced thrombocytopenia (HIT) immunoglobulin and
serotonin release assay were sent and both were positive. Heparin was
discontinued, Argatroban was initiated and ultimately transitioned to
coumadin. Extensive post-operative mobilization and physical therapy
were required for convalescence due to extended ICU stay, patient size,
and a recurrence of severe gout that immobilized him for several days.
Ultimately, the patient discharged on POD 19 not requiring dialysis or
supplemental oxygen, ambulating and tolerating a diet.
Our most recent patient who underwent MIPE for massive saddle PE, and
the fifth patient in our series total, underwent the procedure, was
extubated on POD 0, transferred to the general care floor on POD 1 and
discharged home on POD 3.