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CVD (Part 1) Review KHPM324

Lecture 11: CVD (Part 1) Review

Overview

  • Instructor: Hannah Oh, ScD

  • Course: KHPM324 Chronic Diseases of Modern Society

  • Affiliation: Division of Health Policy & Management, College of Health Sciences, Korea University

Cardiovascular System Overview

Heart Structure and Function

  • Right Side of the Heart

    • Accepts oxygen-depleted venous blood that has already circulated to body cells.

    • Blood is pumped out of the right side of the heart to the lungs.

  • Gas Exchange in Lungs

    • Takes place in the lungs where blood picks up oxygen and releases carbon dioxide.

  • Left Side of the Heart

    • Receives oxygen-rich blood from the lungs.

    • This oxygenated blood is destined for body cells.

Blood Flow Distribution

  • Blood reaching the small intestine supplies oxygen and nutrients to intestinal cells, which also pick up nutrients from digestion.

  • Nutrient-rich venous blood leaves the small intestine and travels via a portal vein to the liver.

  • Near the small intestine, lymph vessels pick up fats, which are eventually returned to the blood.

  • Blood reaches the kidney, where waste products, excess nutrients, and water are removed, and the removed substances are excreted via urine. Filtered blood returns to circulation.

Blood Pressure

Systolic vs. Diastolic Blood Pressure

  • Systolic Blood Pressure (수축기혈압)

    • When blood is pumped out of the heart.

  • Diastolic Blood Pressure (이완기혈압)

    • When the heart is at rest and the left ventricle relaxes and refills with blood from the left atria.

Blood Pressure Regulation

  • Key Formula: Blood pressure = Cardiac output x Vascular resistance

  • Normal Cardiac Output: 5 L/min

  • Vasoconstriction and Vasodilation:

    • Mechanisms used to redistribute blood to essential areas of the body.

Coronary Artery Disease

Overview

  • Definition

    • Most common type of heart disease.

    • Leading cause of death worldwide.

    • Occurs when the arteries that supply blood to heart muscle become hardened and narrowed due to atherosclerosis (buildup of cholesterol and other material, called plaque, on their inner walls).

Pathophysiology

  • As the plaque grows, less blood can flow through the arteries, and the heart muscle can't get the blood or oxygen it needs, leading to:

    • Chest pain (angina)

    • Heart attack

  • Most heart attacks happen when a blood clot suddenly cuts off the heart's blood supply, causing permanent heart damage.

  • Over time, coronary artery disease weakens the heart muscle and can contribute to heart failure and arrhythmias (changes in the normal beating rhythm of the heart).

Consequences

  • Heart Failure: The heart can't pump blood adequately to the rest of the body.

  • Arrhythmias: Abnormal heart rhythms.

Disease Progression

  • Atherosclerosis → Plaque stability → Plaque Rupture → Thrombosis (blood clot) → Arrhythmia → Angina → Myocardial Infarction/Acute Coronary Syndrome → Death

    • Timeline: Years to weeks to minutes.

Plaque Development and Risk

  • Fatty deposits called plaque develop in the arterial walls supplying blood to the heart or brain.

  • If plaque becomes unstable and ruptures, a clot forms inside the artery, leading to reduced blood flow and potential heart attack or stroke.

    • If one or more arteries are partly clogged, angina may occur.

    • Myocardial Infarction: Resulting from complete occlusion of the blood supply to the heart.

Risk Factors for CVD

Established and Novel Risk Factors

  • Dyslipidemia

  • Hypertension

  • Diabetes

  • Inflammatory Pathways

  • Thrombosis

  • Arrhythmic Risk

  • Adiposity

  • Endothelial Dysfunction

  • Metabolic Dysfunction

  • Poor Dietary Habits

  • Physical Inactivity

  • Smoking

Clinical Endpoints

  • Death

  • Coronary Disease

  • Arrhythmias

  • Heart Failure

  • Stroke

  • Cognitive Decline

Hypertension

Overview

  • Definition: High blood pressure (e.g., 140/90).

  • Most patients have essential hypertension, which cannot be attributed to a specific renal or adrenal disease and involves complex pathophysiology.

Dietary Treatment

  • Three Cornerstones:

    • Healthful dietary pattern

    • Reduced sodium intake

    • Reduced body fat

Sodium and Blood Pressure

  • High sodium intake linked to increased blood pressure and cardiovascular disease.

  • Mechanisms Underlying Hypertension:

    • Sodium loading increases blood volume, leading to increased blood pressure via various physiological responses.

    • Impaired sodium elimination can cause hypertension through increased peripheral resistance due to vasoconstriction.

Vascular Resistance

  • Increase in artery stiffness with age, which can be reduced by healthful dietary patterns such as the DASH diet.

Healthful Dietary Patterns

Benefits

  • Healthful dietary patterns can reduce blood pressure.

  • Most studied patterns:

    • DASH Diet: Dietary Approaches to Stop Hypertension.

    • Mediterranean Diet: Rich in healthy fats, fiber, and antioxidants.

Additional Findings

  • Randomized trials show additive benefits of the DASH diet with weight loss on arterial stiffness, measuring decreases in systolic blood pressure and central artery stiffness.

Physical Activity and CVD

Findings from Research

  • Associations of Physical Activity (PA) with CHD Prevention:

    • Active individuals have approximately 20-30% lower rates of coronary heart disease compared to inactive individuals.

    • Physically fit individuals exhibit 30-40% lower CHD rates.

    • Evidence suggests likely causal relationships based on over 100 studies.

Physical Activity Guidelines

  • Adults gain health benefits from any level of physical activity.

  • Recommended Activity:

    • 150 min/week of moderate-intensity aerobic activity reduces chronic disease risk.

    • For additional benefits, aim for 300 min/week.

    • Muscle-strengthening activities should be performed 2+ days/week.

Mechanisms Linking PA and CHD

  • Anti-atherogenic effects.

  • Decreased risk of thrombosis.

  • Decreased risk of myocardial ischemia.

  • Decreased risk of ventricular arrhythmia.

Summary

  • Moderate-intensity physical activity is sufficient to decrease CHD risk.

  • There is a dose-response relationship where higher intensity physical activity yields greater benefits, particularly for weight control.

  • Weight control requires balancing caloric intake with expenditure; 150 min/week may be insufficient for some individuals requiring weight control strategies.