Coronary artery disease

Question 1

Coronary artery blood flow is primarily during? Extraction of blood in the coronaries is usually what? during stress?

Answer 1

• Coronary artery blood flow is primarily during diastole – Myocardial contraction (systole) increases intramyocardial vascular resistance
• Extraction of Oxygen in the coronary bed averages 75% under normal conditions – 100% during stress

Question 2

What is coronary atherosclerosis?

Answer 2

• When plaque reduces coronary crosssectional area by 75% (50% diameter) the resistance to flow becomes significant
• May be adequate flow at rest
• Exercise, stress may increase oxygen demand and result in ischemia/angina
• Acute Myocardial Infarction (MI)

Question 3

What are the four classes of atherosclerosis listed by the new york heart association?

Answer 3

• Class I – No Symptoms, no limitation of activity
• Class II – Symptoms with Ordinary activity
• Class III – Symptoms even with less than ordinary activity
• Class IV – Symptoms at Rest, any activity causes symptoms

Question 4

Classes of angina by the canadian heart association?

Answer 4

• Class I – Angina from strenuous exertion
• Class II – Slight limitation of normal activity
• Class III – Marked limitation of normal activity
• Class IV – Any physical activity accompanied by pain; pain may be present at Rest

Question 5

Diagnosis of CAD?

Answer 5

• Complete History and Physical Exam
• Resting Electrocardiogram – EKG / ECG – Normal in over 50% of patients
• Cardiac Stress Test – Exercise – Chemical - Persantine – Radionuclide

Question 6

Cardiac cath does what for cad?

Answer 6

• Determines presence & extent of CAD – Coronary arteriography – Intra-cardiac pressures measurements • Highest sensitivity & specificity of any test

Question 7

CTA use for CAD?

Answer 7

• Detects & Quantifies degree of coronary artery calcification – Coronary Calcification scoring system – Can be correlated with the presence of hemodynamicallysignificant coronary lesions • Expensive – may not be reimbursed • Primarily a Screening Tool

Question 8

Perfusion studies for CAD?

Answer 8

• May be useful in making treatment decision – May provide information regarding myocardial viability in patients with poor ventricular function. – In patients with borderline anatomic indications for coronary revascularization. • Radionuclide scanning - exercise • Stress Echocardiography • PET scan

Question 9

Medical treatment of CAD?

Answer 9

• Primary Care Physician directed
• Cardiologist assisted
• Risk Factor modification (examples) – Smoking – Diet • Medical Management (examples) – Hypertension controlled – Lipid management

Question 10

Therapeutic intervention versus medical treatment of CAD?

Answer 10

• Severe or Progressive angina on appropriate medical therapy • Ischemic Cardiomyopathy • Multi-vessel coronary artery obstruction – Multi-vessel disease in Diabetics • Reduced Ventricular Function • Significant Left Main Coronary artery stenosis

Question 11

what is the pre-op evaluation for CAD intervention?

Answer 11

• H&P
• Carotid Arteries - Bruits – Carotid Duplex scanning
• Respiratory status – Pulmonary Function Tests (PFT)
• Renal Function – May be affected by the cardiac catheterization
• Blood coagulation evaluation

Question 12

Pre-operative discussion for CAD intervention?

Answer 12

• Discuss Risk vs. Benefit with patient & family – Goals & Anticipated Results of Surgery
• Freedom from Symptoms
• Ability to Live a Normal or Better Life/Lifestyle
• Prolong Life – Potential Risks and Complications – “What if I don’t have surgery?”
• Quality of Life vs. Quantity of Living
• As atherosclerosis is a progressive disease there is a risk of recurrence of disease/blockages: – Native vessels that have Not been bypassed – Bypass grafts
• There is a risk of needing additional intervention in the future – Surgery – PCI – ‘Something that may not even exist today’

Question 13

what is CABBAGE?

Answer 13

• Coronary Artery Bypass Graft Surgery
• Bypass of obstructed vessels – especially if complex disease
• Median-sternotomy
• Aorto-Coronary Bypass –Veins –Arteries

Question 14

Significance of the IMA?

Answer 14

• Internal Mammary Artery –Internal Thoracic Artery (I.T.A.) –Left IMA usually, Right also • Used in majority of CABG surgeries • Conduit of choice to anterior wall distribution (LAD) • Occasionally used as a ‘free graft’

Question 15

Venous grafts? What are other conduits?

Answer 15

Reversed Saphenous Vein Graft • RSVG • Most common conduit • Greater Saphenous Vein • Lesser Saphenous Vein • Cephalic Vein • Endoscopic vein harvest

What are other conduits: • Radial Artery • Gastro-epiploic artery • Cryopreserved cadaver vein

Question 16

What is cardiopulmonary bypass?

Answer 16

• Utilized for most cardiac surgical procedures • Extracorporal Circulation – “Heart Lung Machine” • With or Without Systemic Hypothermia • Systemic Heparinization – 3-4 mg/kg – 20,000 to 40,000 units of heparin

Question 17

What is cannulation?

Answer 17

• Connection to the “heart lung machine”
• Arterial Cannulation Arterial Inflow – Aortic cannula – Femoral artery cannula

• Venous - Blood return to the pump – Right atrial cannula – Bi-caval cannula – Femoral cannula

Question 18

What is the processes for CABBAGE?

Answer 18

• Patient is placed on “Bypass”
• Aorta is Cross Clamped – Clamp placed on the Ascending Aorta – Stops direct circulation to the heart • Infuse Cardioplegia – Arrest & Protects the heart – Reduces myocardial oxygen consumption – Potassium solution – Cold
• Conduit is sutured to the coronary artery distal to the obstruction/stenosis
• distal anastomoses
• After distal anastomoses are completed the cross clamp may be removed
• “Proximal Anastomoses” –Vein (or radial artery or IMA free graft) is sutured to the ascending aorta
• Cardiac rhythm is restored
• Patient is weaned from cardiopulmonary bypass –Cannulas are removed
• Chest is closed

Question 19

What is OPCAB? Advantage? Disadvantages?

Answer 19

• OPCAB - Off-Pump Coronary Artery Bypass – “Beating heart surgery” – Most widely used of less invasive approaches – 10%
• Median sternotomy or limited incision – Cardiopulmonary bypass is eliminated – Myocardial Stabilizer device is utilize

Advantage: • Elimination of the systemic effects of cardiopulmonary bypass(?) –Hypothermia –Inflammatory response –Micro-emboli • Neurological effects(??) • Mortality(?) • Cost(?)

Disadvantage: • Incomplete revascularization • Reduced early graft patency (?)

Question 20

Explain graft patentcy?

Answer 20

• Graft closure within 30 days: –Usually considered to be technical error –Poor graft quality –Poor target vessel runoff
• Graft closure from 1 month to 3 years –Usually from intimal hyperplasia
• Graft closure after 3 years –Usually atherosclerotic –Progression if disease
• Graft patency is adversely affected by: –Persistent smoking –Elevated LDL cholesterol levels –Not modifying Lifestyle
• Aspirin should be started within 48 hours of surgery
• IMA – 95% 1 year – 90% 10 year
• RSVG (Greater saphenous) – 80-90% 1 year – 50% 10 year
• Radial Artery – 94% 1 year – 83% 5 year
• Cryopreserved cadaver vein - 50% 2 year

Question 21

Prognosis with CABBAGE?

Answer 21

Prognosis with CABG
• Isolated CABG – Mortality is 2.8% – 1% will require repeat revascularization • CABG is most beneficial in patients with: – Multi-vessel disease • Diabetes – Reduced ventricular function – Left main coronary involvement – NYHA class IV symptoms

Successful revascularization: • Improves resting left ventricular wall motion in many patients • Improved exercise tolerance

Predictors of late cardiac mortality after CABG: • Diabetes • Advanced age • Reduced ejection fraction • Non-use of the IMA

• 5 year: –92% survival –83% freedom from angina
• 10 year –81% survival –63% freedom from angina

Question 22

Predictors of mortality for CABBAGE?

Answer 22

Acute MI 6.12 Cardiogenic Shock 7.89 Emergent Surgery 12.39

Question 23

Reoperation for CAD?

Answer 23

• “Redo” • Progression of disease of native vessels • Occlusion of Bypass grafts • Technically more difficult procedure • Mortality/complication rates are higher

Question 24

Other complications with CAD?

Answer 24

Post-Infarction Ventricular Septal Defect: • V.S.D. • <1% • Interval from MI to VSD – 1 to 12 days • Prognosis poor – 24% will die on day of rupture – 65% die by end of 2 weeks – 81% die by 2 months

Left Ventricular Aneurysm
• Occur with large MI – MI progresses to thinned-out, transmural scar • Bulges paradoxically during systole • Occurs in 2-4% of MIs – Incidence is probably decreasing because of more aggressive acute MI management • 90% involve the anteroseptal left ventricle • 10% are posterior • Over 50% contain thrombus