Coronary artery disease Flashcards
Coronary artery blood flow is primarily during? Extraction of blood in the coronaries is usually what? during stress?
- 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
What is coronary atherosclerosis?
- 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)
What are the four classes of atherosclerosis listed by the new york heart association?
- 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
Classes of angina by the canadian heart association?
- 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
Diagnosis of CAD?
- Complete History and Physical Exam
- Resting Electrocardiogram – EKG / ECG – Normal in over 50% of patients
- Cardiac Stress Test – Exercise – Chemical - Persantine – Radionuclide
Cardiac cath does what for cad?
• Determines presence & extent of CAD – Coronary arteriography – Intra-cardiac pressures measurements • Highest sensitivity & specificity of any test
CTA use for CAD?
• 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
Perfusion studies for CAD?
• 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
Medical treatment of CAD?
- Primary Care Physician directed
- Cardiologist assisted
- Risk Factor modification (examples) – Smoking – Diet • Medical Management (examples) – Hypertension controlled – Lipid management
Therapeutic intervention versus medical treatment of CAD?
• 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
what is the pre-op evaluation for CAD intervention?
- 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
Pre-operative discussion for CAD intervention?
- 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’
what is CABBAGE?
- Coronary Artery Bypass Graft Surgery
- Bypass of obstructed vessels – especially if complex disease
- Median-sternotomy
- Aorto-Coronary Bypass –Veins –Arteries
Significance of the IMA?
• 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’
Venous grafts? What are other conduits?
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
What is cardiopulmonary bypass?
• 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
What is cannulation?
- 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
What is the processes for CABBAGE?
- 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
What is OPCAB? Advantage? Disadvantages?
- 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 (?)
Explain graft patentcy?
- 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
Prognosis with CABBAGE?
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
Predictors of mortality for CABBAGE?
Acute MI 6.12 Cardiogenic Shock 7.89 Emergent Surgery 12.39
Reoperation for CAD?
• “Redo” • Progression of disease of native vessels • Occlusion of Bypass grafts • Technically more difficult procedure • Mortality/complication rates are higher
Other complications with CAD?
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
