Ischemic Heart Disease (IHD) Overview

• Ischemic Heart Disease (IHD) is explored

Overview of IHD

• IHD encompasses Acute Coronary Syndrome (ACS), ischemic heart disease, and ischemic cardiomyopathy
• Connective tissue disorders and cardiac pathologies are related to IHD
• Atherosclerotic plaque plays a role in IHD
• Angina Pectoris, Myocardial Infarction, and Sudden Cardiac Death are forms of IHD

Oxygen Supply Chain

• The oxygen supply chain involves the lungs, heart, and tissues, ensuring oxygen delivery and carbon dioxide removal
• Oxygen is consumed by the mitochondria within tissues; carbon dioxide is produced
• The heart pumps blood, facilitating oxygen and carbon dioxide exchange between the lungs and peripheral tissues

Key Terms

• Ischemia is a condition where blood flow, and therefore oxygen, is restricted or reduced to an area of the body
• Hypoxemia indicates a low oxygen content in the blood, reflected in Low O₂ Saturation
• Hypoxia occurs when the body or a region is deprived of an adequate oxygen supply at the tissue level

Acute Coronary Syndrome (ACS)

• ACS is an umbrella term for symptoms linked to sudden, reduced blood flow to the heart
• ACS includes heart attack (MI), unstable angina, ST segment elevation MI (STEMI), and Non-ST segment elevation myocardial infarction/heart attack (NSTEMI)
• ACS diagnosis considers the patient's history of chest or left arm pain, and CAD history
• Examination involves monitoring for hypotension and diaphoresis
• ECG changes, namely ST-segment deviation, are key indicators
• Elevated cardiac biomarkers, including TnI, TnT, and CK-MB, are diagnostic markers

Basic Classification and Definition of Ischemic Heart Disease (IHD)

• IHD can also be called Coronary Heart Disease (CHD), Coronary Artery Disease (CAD), or Atherosclerotic Heart Disease (ASHD)
• IHD covers conditions where the heart muscle doesn't receive enough blood
• Acute Coronary Syndrome is a more serious and acute presentation of IHD

Occurrence and Atherosclerosis

• In the US and Western Europe, IHD is the most common cause of death
• IHD is linked to atherosclerotic injury to the coronary arteries

Causes of IHD

• Atherosclerosis of the coronary arteries is the most common factor
  • This involves a progressive inflammatory disorder with localized lipid deposits in the arterial wall
• Coronary thrombus or emboli
• Coronary spasm (vasospasm), where smooth muscle contraction closes the vessel
• Complications of connective tissue can be a cause

Risk Factors for IHD

• Age, hypertension (HTN), and diabetes
• Gender
• Smoking
• Physical inactivity and obesity
• Hyperlipidemia
• High stress levels
• Family history
• Poor diet

Common Symptoms of IHD

• Chest pain or discomfort, described as pressure, tightness, or fullness
• Pain or discomfort in one or both arms, the jaw, neck, back, or stomach
• Shortness of breath
• Feeling dizzy or lightheaded
• Fatigue
• Sweating (diaphoresis)
• Insomnia
• Swelling in lower extremities

Diagnostics for IHD include:

• Blood testing for Cardiac enzymes, including troponin and creatine kinase
• C-reactive protein (CRP)
• Homocysteine
• Abnormal lipid profile
• Brain natriuretic peptide (BNP), which senses ventricular stretch
• Prothrombin
• ECG alterations, specifically ST depression

Ischemic Cardiomyopathy

• Occurs when the heart is chronically ischemic, experiencing reduced blood flow
• Cardiomyopathy involves disease of the heart muscle, with reduced contractility
• Narrowing of coronary arteries diminishes blood supply
• CAD causes insufficient blood flow, leading to myocyte ischemia
• Damaged tissue weakens and dilates the chamber, leading to dilated cardiomyopathy
• Chronic CAD leads to myocyte damage, which can result in cardiac remodeling, myocardial fibrosis, arrhythmias, and possible cardiac conduction system impairments
• Cell death and left ventricular enlargement/dilation can occur
• Worsening CAD may be a precursor
• Clinical congestive heart failure can develop
• Prognosis is largely based on myocardial viability

Connective Tissue Disorders and Cardiac Pathologies

• Rheumatoid Arthritis is a chronic immune-mediated inflammatory disease
  • Symptoms include morning stiffness, arthralgias, or arthritis
  • Rheumatoid heart disease occurs in 25-40% of RA patients
  • It may appear as pericarditis, myocarditis, valvular heart disease, atherosclerotic CAD, coronary arteritis, aortitis, cor pulmonale, or conduction disturbances

Schematic Time Course of Atherogenesis

• Atherosclerosis development can lead to Ischemic Heart Disease, Cerebrovascular Disease, and Peripheral Vascular Disease
• The process begins with lesion initiation and progresses from no symptoms to symptoms over time

Atherosclerotic Plaque

• Key features include a fibrous cap, a lipid core, and the shoulder region
• The plaque is located within the intima, with the media and elastic lamina layers beneath

Angina Pectoris

• Angina pectoris includes both stable and unstable angina
• Angina can lead to myocardial infarction, sudden cardiac death, and ischemic cardiomyopathy

Stable Angina

• Stable angina involves intermittent chest pain caused by transient, reversible myocardial ischemia
• This is caused by a mismatch between oxygen delivery and oxygen demand
• Stable angina is brought on by exertion or stress and occurs at a predictable heart rate
• The sensation is described as a crushing or squeezing substernal discomfort, possibly radiating down the left arm
• Symptoms are reduced by stress reduction

Unstable Angina

• Is brought on by exertion or stress
• Onset is unpredictable
• Involves a crushing or squeezing substernal sensation, possibly radiating to the arm
• Considered an indicator of poor prognosis

Differences Between Stable and Unstable Angina

• Stable angina causes chest pain with activity, relieved with rest; unstable angina causes chest pain with activity and rest
• Stable angina is characterized by inadequate oxygen to heart muscle during activity; unstable angina should be treated as an emergency
• Troponin levels are negative in both stable and unstable angina
• Stable angina is related to a stable plaque, but unstable angina involves plaque rupture and partially blocked coronary arteries

Myocardial Infarction Pathogenesis

• Plaques form in the lumen of the arteries, secondary to inflammation and lipid deposition
• Plaque rupture exposes thrombogenic lipids to the blood
• Then stimulates localized thrombus formation, potentially causing coronary artery occlusion
• Damage from an occlusive event depends on the coronary artery involved and the time until treatment

Myocardial Infarction

• If an ischemic insult is sufficiently prolonged, tissue damage and tissue/whole body death will occur
• "Time is Tissue"
• Substantial tissue damage can occur (acute and chronic) from an infarction or ischemic insult
• Risk increases with age
• It is a disease that affects women as well as men

Anginal Equivalents

• Include chest pain and discomfort, feeling weak, faint, or light-headed
• Pain or discomfort in the jaw, neck, or back
• Pain in the arms or shoulders
• Shortness of breath either before or during chest discomfort
• Indigestion and heartburn

Sudden Cardiac Arrest

• Sudden Cardiac Arrest (SCA) involves unexpected arrest secondary to cardiac or non-cardiac causes, with rapid loss of consciousness
• Cardiac SCA stems from a cardiac issue leading to sudden cessation of cardiac function such as arrhythmia, MI, or aneurysm
• Non-cardiac SCA can result from choking, sepsis, pulmonary embolism, anaphylaxis, or blunt-force chest trauma
• Risk factors and existing disease may be previously documented.
• 50% of deaths from CAD are SCA
• Pathology includes electrophysiology findings, Ventricular Fibrillation, Asystole
• Anatomic findings of cardiac causes include Acute Coronary Plaque Rupture or Thrombosis, clinically quiet MI, or greater than 60% stenosis of a coronary artery, often the LAD

Commotio Cordis

• Commotio Cordis is caused by a blow to the chest over the heart at a vulnerable time in the cardiac cycle, which induces ventricular fibrillation and sudden cardiac arrest