Transcript Coronary surgery - Ipswich-Year2-Med-PBL-Gp-2

Coronary Artery Surgical
Interventions
Percutaneous Coronary
Intervention (PCI)
• These interventions include balloon angioplasty, intracoronary stent
implantation, as well as rotational and laser atherectomies (The
surgical procedure to remove plaque from an artery).
• Uses the same technique as coronary
angiography/cardiac catheterization
– access to the arterial system is obtained, via femoral
artery
– A catheters is advanced, up through aorta to the left
and right coronary arteries
– Radiopaque contrast is injected and imaging taken of
the flow through the coronary artery
• to clearly define the vascular anatomy and to quantify the
severity of occlusive lesions
PCI procedure
– A guidewire, with a balloon tipped-catheters can then
be advanced across the stenosis and inflated
• This stretches and dilates the affected vessel, restoring the
lumen to its predisease dimensions. (40% restenosis)
– The use of nitinol scaffolding stents has greatly
reduced restenosis rates to nearly 15%; they are
used in nearly 90% of percutaneous procedures in
the United States.
– the latest advancement is the drug-eluting stent, with
antiproliferative drugs impregnated into the walls
– Reports of stent thrombosis have raised concerns,
and indefinite use of antiplatelets is recommended.
Coronary Artery Bypass Grafting
(CABG)
INTRO
• Since its inception in 1967, coronary artery
bypass grafting (CABG) has increased in volume
• This growth has slowed in the last decade
presumably from improved percutaneous and
medical treatments
• Despite the recent trends, CABG continues to be
among the most frequent, successful, and wellstudied procedures performed in medicine.
• PRINCIPLE OF CABG: to restore normal
myocardial perfusion by creating alternative routes
for blood to reach the vulnerable tissue
MAKING THE CONDUIT/S
• A variety of conduits may be chosen
• the most traditional and still most frequently utilized
is the saphenous vein, gained via a saphenectomy.
• the internal mammary artery can also be mobilized
from the chest wall and anastomosed to a coronary
artery. Most commonly the L internal mammary is
anastomosed to the LAD. The right can also be
used, but using both  risk of sternal ischemia and
surgical wound-healing complications
• internal mammary graft has better patency then
saphenous vein grafts.
Preparing for grafting
• the standard approach for coronary bypass
grafting is via the median sternotomy to
expose the heart and great vessels.
• The left thoracotomy could be alternatively used,
particularly after previous heart surgery where
sternal reentry could hazard injury to adhesed
cardiac structures or patent grafts.
• Preparation is then made to institute
cardiopulmonary bypass (CPB).
Cardiopulmonary Bypass
•
•
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Insert canulla into R atria to drain
blood to cardiotomy reserve, and
insert canulla into ascending aorta to
receive back the ‘arterial inflow’ ie.
bypass the lungs and heart
The machine oxygenates the blood
but also cools the blood to 28–32 °C
to reduce tissue oxygen
requirements and organ injury.
Cardioplegic arrest is then initiated
by cross-clamping the ascending
aorta and infusing
– autologous blood with crystalloid
solution cooled to 12 °C containing
citrate to bind ionic calcium, dextrose,
pH buffers, and potassium to arrest
cardiac activity.
•
With the arrested heart, a dry and
motionless surgical field is created
Ready to do grafting….
•
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the sites for grafting/bypass are determined on the
basis of information from the preoperative
angiography. An arteriotomy is created on the
exposed vessel, and it is extended for
approximately 5 mm. The conduit is positioned and
the anastomosis created
After completion of all anastomoses, weaning from
CPB is prepared
– The patient is warmed to normothermia.
– As the heart begins to warm, ventricular fibrillation
often occurs, requiring electrical defibrillation.
– Mechanical ventilation is resumed, and the patient is
gradually weaned from CPB.
– Pharmacologic inotropic support may be required
•
Once haemostasis is adequate, chest closure is
performed with stainless steel wires. The
pericardium is typically left open to avoid
constriction of the atria or kinking of the bypass
grafts.
Outcomes
• Overall, risk of perioperative death remains at 1–3%.
• Multivariate predictors of death include advanced age,
recent myocardial infarction, decreased ventricular
function, renal insufficiency, and female gender.
• Late failures appear to occur at a rate of 5% per year,
with 10-year patency approximately 40–50%. Late
failures are primarily attributed to accelerated
atherosclerosis of the vein conduit
• The pedicled internal mammary artery has far superior
patency, particularly when anastomosed to the LAD.
With adequate target vessel runoff, 10-year patency
rates of 90–95% have been reported in multiple
independent studies
Future of CABG
• Recently, attempts to reduce the invasive nature of coronary bypass
grafting and the potential complications of CPB have been
introduced.
• Techniques to perform bypass grafting without CPB have
improved
• Off-pump coronary bypass grafting (OPCAB) have potential
advantages in reducing neurologic complications associated
with air and atheroemboli, as well as reducing blood transfusion
requirements and cost.
• The procedure involves manipulation and stabilization of the beating
heart to expose the epicardial targets. Particularly for vessels on the
posterior and posterolateral surfaces, hemodynamic instability can
result while the heart is elevated and rotated for optimal exposure
• Still has reduced graft patency rates so not increased over the last
several years.
Indications for surgical intervention
• The decision to proceed with revascularization, as
opposed to continuing medical therapy, is made in three
groups of stable patients:
– Patients with activity-limiting symptoms despite maximum
medical therapy
– Active patients who want PCI for improved quality of life
compared to medical therapy, such as those who are not
tolerating medical therapy well, or who want to increase their
activity level.
– Patients with anatomy for which revascularization has a
proven survival benefit such as significant left main coronary
artery disease (greater than 50 percent luminal narrowing) or
multivessel coronary artery disease (CAD) with a reduction left
ventricular ejection fraction and a large area of potentially
ischemic myocardium.
CABG VERSUS PCI
The choice of CABG versus PCI is dependent upon a number of factors:
• particularly the location and number of vessels involved:
– PCI with drug-eluting stents has been preferred in patients with one or two vessel
disease
– CABG has been preferred when there is a large amount of myocardium at risk,
eg. left main coronary disease, and diffuse three-vessel coronary disease
Patient factors
– PCI may be attempted in younger patients who may otherwise be expected to
require one or more bypass operations in their lifetime due to progression of
CAD and to saphenous vein graft degeneration. Reoperation is associated with
higher perioperative mortality and is less often fully successful.
– PCI preferred in older patients or those with significant comorbidity who may
have prohibitively high operative risks or short life expectancies.
– Patients who refuse open heart surgery
References
• Haft, J. CURRENT Diagnosis &
Treatment: Surgery, 13e. The Heart: I.
Surgical Treatment of Acquired Cardiac
Disease. Accessed:
www.assessmedicine.com.au
• Up- to-date. 2010. Bypass surgery versus
percutaneous intervention. Accessed:
www.uptodate.com