cardiovascular risk

Rationale for Concern
- Vascular surgery is unique since vital organs may be completely deprived of their blood supply during surgery
- Highest surgical mortality/morbidity is associated with vascular procedures
Basis for morbidity/mortality associated with vascular surgery:
1. Myocardial failure
2. Myocardial ischemia
3. Myocardial infarction

**Surgical Procedures of Special Concern**
Coronary bypass surgery	Carotid vessel surgery	Aorta surgery	Major vascular surgery (supplying viscera/limbs)

Pathophysiology: Coronary Artery Disease (CAD): The major cause of death in the United States
- Major risk factors in development and progression of atherosclerosis
  - Obesity
  - Oobacco use
  - Inactivity
- Atherosclerotic lesions:
  - Fatty streaks
  - Atheromatous plaques


"Aorta of a young man. It shows fatty streaks (elongated, flat, yellow lesions) and early fibrotic plaques, (broader and slightly elevated lesion)" Courtesy of Jim Fishback, M.D., Department of Pathology, University of Kansas Medical Center	Fatty streak of the aorta, histology Lipid containing cells (probably macrophages) are present in the intima of the aorta" courtesy of Jim Fishback, M.D., Department of Pathology, University of Kansas Medical Center

Atheromatous plaques
- Reduces vessel diameter (luminal diameter)
- Location of thrombosis, vessel wall calcification, vessel wall weakening
- Clinical Consequences:
  - Occlusion
  - Vessel rupture
  - Aneurysmal dissection
- Distribution of atheromatous plaques: Factors--
  - Regions of disturbed blood flow; shear stresses
    - Lower descending aorta {ostia of the major branches}
    - First 3 inches of coronary arteries
    - Descending aorta
    - Internal carotids
    - Circle of Willis
    - Leg arteries
- Atherogenesis: multistep process probably involving: (a) Dysfunctional endothelial cells, (b) induction of growth and coagulation factors, (c) macrophage and monocyte involvement in injury response)
  - Risk factors (hypolipidemia, smoking, hypertension) affect multiple steps
  - Hypertension promotes endothelial damage
  - Abnormal flow/perfusion characteristics increase atherosclerosis development
  - Hyperlipidemia promotes atherosclerosis

"Severe atherosclerosis of the aorta.
The intima of the aorta is eroded and ulcerated, appears rough, and is totally covered with clotted blood."
Courtesy of Jim Fishback, M.D., Department of Pathology, University of Kansas Medical Center

"Aneurysm of the aorta with a thrombus. On opening of the aneurysm at autopsy, a mural thrombus was found partially occluding the lumen of the blood vessel."

"Atherosclerosis of the order with narrowing and thrombosis.
Narrowing of the aorta is one of the common complications of atherosclerosis.
Thrombi overlying the ulcerated endothelium contributes to the narrowing of the lumen and may completely block the blood flow through the narrow part of the blood vessel."
Courtesy of Jim Fishback, M.D., Department of Pathology, University of Kansas Medical Center

Prominent risk factors for atherosclerosis: hypercholesterolemia, tobacco smoking, hypertension
- Hypercholesterolemia: reduction in cholesterol concentration may slow/reverse atherosclerosis
  - Individuals with lower cholesterol exhibited reduction in all-cause mortality {30-year Framingham subject follow-up}
  - Significant lowering of total cholesterol and low-density lipoproteins (LDL) cholesterol associated with:
    - Reduced total mortality (33%)
    - Reduced coronary mortality (42%)
    - Reduced non-fatal coronary infarctions (33%) reduced requirement for coronary revascularization (30%)
- Hypertriglyceridemia:
  - Possible independent risk fact for coronary disease
    - Hypertriglyceridemia--independent risk factor in women {Framingham study}
  - Hypertriglyceridemia associated with reduced high-density lipoproteins levels (HDL levels)
- Tobacco Smoking: Cardiovascular systemic effects
  - Increased sympathetic tone secondary to nicotine absorption
  - Increased platelet adhesiveness
  - Displacement of O₂ by CO
  - Possible immunological reaction in vessel wall
  - Most preventable risk factor for cardiovascular disease
- Hypertension --major risk factor independent of gender, age groups, race
  - Frequency: 10%-20% (USA): elevated blood pressure
  - Hypertension has additive effects with respect to other risk factors.