Cardiac
surgical procedures
Cardiopulmonary
bypass
Most of the cardiac operations rely on extra corporeal
circulation to perfuse the body so that the heart is stopped for precise and
accurate repair. Cannulation of aorta for arterial inflow and of the inferior
venacava (IVC) and superior venacava (SVC) for venous drainage is the most
common form of CPB. After the sternum has been opened, a longitudinal incision
is made in the pericardium from the pericardial reflection at the aorta to the
diaphragmatic portion of the pericardium. Two purse string sutures are inserted
in the ascending aorta just below the great vessels. Aortic canula is inserted
and tightened with tie to the purse string tourniquets. Commonly venous blood
is drained from the right side of the heart via the SVC and the IVC, oxygenates
and pumped back into the systemic circulation. The circulatory system is
heparinised to avoid thrombus formation. Cardiotomy suction lines aspirate
blood directly back to the pump where it is filtered, oxygenated and reinfused
with the rest of the bypass volume into the arterial circulation.
After the CPB is established the heart
is stopped by giving high potassium cardioplegia solution in to the aorta
proximal to the aortic canula after aortic cross clamp. Systemic hypothermia is
used during CPB to reduce the metabolic rate, and subsequently the energy
demands of the organs. Cooling of the myocardium is achieved by using ice chilled
Ringer Lactate or Normal Saline topically.
After the surgical repair has been
completed, the surgeon prepares to discontinue bypass. Patient would have been
rewarmed to normothermia and the heart will be contracting in a regular manner.
The anaesthesiologist starts to ventilate the lungs and the surgeon occludes
the venous line allowing blood to enter the right atrium (RA). When heart’s
pumping action is judged to be sufficient and systemic blood pressures are
stable, the venous line is clamped completely, and the heart resumes
responsibility for maintaining the circulation. After bypass has been
discontinued, and heparin reversal with protamine sulphate is begun, the CPB
cannula is removed. Defibrillation by the internal application of a direct
current (DC) electrical shock to the myocardium is instituted when the heart
fibrillates.
Coronary
artery bypass graft (CABG)
CABG is done to bypass the blocked or diseased coronary
arteries using the saphenous vein and the internal mammary artery and radial
artery. This is done as beating heart surgery or using CPB machine.
i. On pump CABG, we need to stop the patient’s heart and connect
the patient to heart lung machine. This machine takes over the patients’
cardiac and pulmonary function and delivers oxygenated blood through out the
body and brain while bypass is performed.
ii.Off pump CABG (beating heart) eliminates the need for stopping
the heart and use of CPB. It is mostly done for patients with lesions in the
left anterior descending, diagonal and occasionally the right coronary
arteries. Surgeon operates directly on the beating heart using Octopus, a
coronary stabilizer placed around the target coronary artery, minimizes cardiac
motion and allows the surgeon to perform the anastomosis.
Endoscopic vein harvesting is a
minimally invasive approach to saphenous veinharvesting.In this, 1-3 incisions
are made on the leg and the vein is located under direct vision using a camera
attached to the video externally. The remaining length of vein is excised via
the video assistance with endoscopic scissors and clips. The benefit of using
vasoview desection are small incision instead of vein length incision, less
post operative pain, less scarring and less infection.
Cardiac
ablation
This is done using epicor ultra cinch ablation
device. This is performed in patients with AV reentry tachycardia (WPW
syndrome). In cardiac ablation a radio frequency energy is rendered to
inactivate the accessory pathway.
Valve
surgeries
All valve surgeries are done after establishing CPB. The
usual valve prostheses used are TTK chitra valve, St.Jude mechanical valve,
Starr-Edwards mechanical valve, Medtronic valves and Perimount bioprosthetic
valve.
i. Aortic valve
replacement -Aorta is opened under CPB, diseased valve is
removed and replaced with a prosthetic or bioprosthetic valve. The prosthetic
valve is placed using non absorbable sutures.
ii. Mitral valve
replacement-Diseased mitral valve is removed and replaced
with artificial prosthetic or bioprosthetic valve. Single valve replacement and
double valve replacement are usually performed here.
iii. Valve
repairs-Mitral valve reparative procedure is
also being done because of the complications associated with prosthetic
replacement and anticoagulation. Carpentier Edwards mitral and tricuspid rings
(DE-VEGA suture annuloplasty) are used for annuloplasty.
Surgical repair of ASD
is done under CPB
Tanned pericardial patch is used to close the defect.In
sinus venosus defect, redirection of anomalous pulmonary venous return is also
done. In ostium primum defect mitral valve cleft is sutured.
Vascular
surgeries
Aneurysm
repair
Surgical repair of the aneurysm depends
on the location. Usually involves excision of the bulging section and replacing
the weakened section of the vessel with a prosthetic graft. If the aneurysm is
located in the ascending aorta just above the heart, the heart-lung machine
will be used. In ascending aortic aneurysm with aortic valve involvement, a
conduit is used to replace the diseased aorta and valve and the coronary
arteries are stitched to the graft at separate openings (Bentall-De Bono
procedure).
Embolectomy
It is the rapid removal of emboli and thrombi from the
vascular system. An
embolectomy is the surgical
removal of an embolus in a blood vessel and is done by using Fogarty’s
embolectomy catheter.
Aortofemoral
bypass graft
Peripheral artery bypass is the surgery to reroute the blood supply around a blocked artery in
the legs mainly for chronic occlusions from atherosclerosis. The common
procedures include aorto- femoral bypass and femoropopletial bypass using
artificial grafts.
Carotid endarterectomy
It is the surgery
used to remove plaque from the carotid artery. During the operation, the
surgeon peels off the plaque from the carotid artery. Once the plaque is
removed from the carotid artery, the artery is repaired using saphenous vein.
During the operation the blood flow to the brain is maintained using a special
shunt (Pruitt-Inahara shunt).
Vascular
access for hemodialysis
An
arteriovenous fistula (A-V fistula) is made by joining an artery and a vein
usually in the forearm (radial artery and vein). This is done for subjects who
need long-term dialysis, and is done under local anesthesia.
We perform open heart, closed heart as well as thoracic and
vascular surgeries. Open-heart surgeries are mostly done with the help of
cardio pulmonary bypass (CPB) /heart lung machine. Beating heart surgeries are
also being done here. Approach to open heart surgery is mainly through a median
sternotomy incision, which provides excellent exposure for surgery of the heart
and great vessels and facilitates canulation for a CPB.
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