Disorders of Cardiac Function

Definition and Functions of the Pericardium
Definition
A double-layered serous membrane
Functions
Isolates the heart from other thoracic structures
Maintains its position in the thorax
Prevents it from overfilling
Contributes to coupling the distensibility between the two ventricles during diastole; they both fill equally
Types of Pericardial Disorders
Pericardial effusion
The accumulation of fluid in the pericardial cavity
Cardiac tamponade
Slow or rapid compression of the heart due to accumulation of fluid, pus, or blood in pericardial sac
Pericarditis
An acute inflammatory process of the pericardium
Can be acute, chronic or constrictive
Coronary Heart Disease
Impaired coronary blood flow that may cause:
Angina
Myocardial infarction or heart attack
Cardiac arrhythmias
Conduction defects
Heart failure
Sudden death
The Evaluation of Coronary Blood Flow and Myocardial Perfusion
ECG
Echocardiogram
M-mode, two-dimensional, Doppler, and esophageal
Exercise stress testing
Motorized treadmill and bicycle ergometer
Nuclear cardiovascular imaging methods
Myocardial perfusion imaging, infarct imaging, radionuclide angiocardiography, and positron emission tomography

Types of Artherosclerotic Lesions
Fixed or stable plaque
Obstructs blood flow
Implicated in stable angina
Unstable or vulnerable plaque
Can rupture and cause platelet adhesion and thrombus formation.
Implicated in unstable angina and myocardial infarction
Major Determinants of Plaque Vulnerability to Rupture
The size of the lipid-rich core and the stability and thickness of its fibrous cap
The presence of inflammation with plaque degradation
The lack of smooth muscle cells with impaired healing and plaque stabilization
Plaques with a thin fibrous cap overlaying a large lipid core are at high risk for rupture


Antiplatelet and Anticoagulant Therapy
Aspirin
The preferred antiplatelet agent for preventing platelet aggregation in persons with CHD
Inhibits synthesis of prostaglandin, thromboxane A2
Ticlopidine and clopidogrel
May be used when aspirin is contraindicated
Irreversibly inhibits the binding of ADP to its receptor on the platelets; no effect on prostaglandin synthesis


Antiplatelet and Anticoagulant Therapy (cont.)
Platelet Receptor Antagonists
Target a single step in the aggregation process
Block the receptor involved in the final common pathway for platelet adhesion, activation, and aggregation
Treat acute coronary syndrome
Classification of Coronary Heart Disease
Chronic ischemic heart disease
Chronic stable angina, silent myocardial ischemia, and variant or vasospastic angina
Acute coronary syndromes
Represent the spectrum of ischemic coronary disease ranging from unstable angina through myocardial infarction

Types of Angina
Chronic stable angina
Associated with a fixed coronary obstruction that produces a disparity between coronary blood flow and metabolic demands of the myocardium
Stable angina
The initial manifestation of ischemic heart disease in approximately half of persons with CHD
Populations Affected by Silent Myocardial Ischemia
Persons who are asymptomatic without other evidence of CHD
Persons who have had a myocardial infarct and continue to have episodes of silent ischemia
Persons with angina who also have episodes of silent ischemia
Non-pharmacologic Treatment of Angina
Smoking cessation in persons who smoke
Stress reduction
Regular exercise program
Limiting dietary intake of cholesterol and saturated fats
Weight reduction if obesity is present
Avoidance of cold or other stresses that produce vasoconstriction
Determinants of ACS Status
Persons with an ACS are routinely classified as low risk or high risk for infarction based on:
Presenting characteristics
ECG variables
Serum cardiac markers
The timing of presentation

Causes of Unstable Angina
Atherosclerotic plaque disruption
Platelet aggregation
Secondary hemostasis
Characteristics of Pain Associated with Unstable Angina
The pain has a more persistent and severe course and is characterized by at least one of three features:
It occurs at rest (or with minimal exertion) usually lasting more than 20 minutes (if not interrupted by nitroglycerin)
It is severe and described as frank pain and of new onset
It occurs with a pattern that is more severe, prolonged, or frequent than previously experienced

Basis for Diagnosis of Unstable Angina
Pain severity and presenting symptoms
Hemodynamic stability
ECG findings
Serum cardiac markers
Manifestations of ST-segment Elevation AMI
Abrupt onset
Severe and crushing pain, usually substernal, radiating to the left arm, neck, or jaw
Gastrointestinal complaints (nausea and vomiting)
Complaints of fatigue and weakness
Tachycardia, anxiety, restlessness, feelings of doom
Pale, cool, and moist skin
Factors Determining the Extent of an Infarct
Location and extent of occlusion
Amount of heart tissue supplied by the vessel
Duration of the occlusion
Metabolic needs of the affected tissue
Extent of collateral circulation
Heart rate, blood pressure, and cardiac rhythm
Involvement of Heart Muscle in an Infarct
Transmural infarcts
Involve the full thickness of the ventricular wall
Occur when there is obstruction of a single artery
Subendocardial infarcts
Involve the inner one third to one half of the ventricular wall
Occur more frequently in the presence of severely narrowed but still patent arteries
Medical Management Following Infarct
Thrombolytic therapy
Revascularization interventions
Coronary artery bypass grafting (CABG)
Percutaneous coronary intervention (PCI)
Atherectomy
Cardiac rehabilitation programs
Myocardial Diseases
Myocarditis
Inflammation of the heart muscle and conduction system without evidence of myocardial infarction
Primary cardiomyopathies
Heart muscle diseases of unknown origin
Secondary cardiomyopathies
Conditions in which the cardiac abnormality results from another cardiovascular disease, such as myocardial infarction
Types of Cardiomyopathies
Dilated
Hypertrophic
Restrictive
Arrhythmogenic Right Ventricular
Peripartum

Predisposing Factors for Endocarditis
A damaged endocardial surface
A portal of entry by which the organism gains access to the circulatory system
The presence of valvular disease, prosthetic heart valves, or congenital heart defects provides an environment conducive to bacterial growth
In persons with preexisting valvular or endocardial defects, simple gum massage or an innocuous oral lesion may afford the pathogenic bacteria access to the bloodstream
Manifestations of Rheumatic Fever
Acute stage
History of an initiating streptococcal infection
Involves mesenchymal connective tissue of the heart, blood vessels, joints, and subcutaneous tissues
Recurrent phase
Extension of the cardiac effects of the disease
Chronic phase
Permanent deformity of the heart valves
Function and Disorders of the Heart Valves
Function: Promote directional flow of blood through the chambers of the heart
Dysfunction results in disorders:
Congenital defects
Trauma
Ischemic damage
Degenerative changes
Inflammation
Disruptions Occurring with Valvular Heart Disease
Narrowing of the valve opening so it does not open properly
Stenosis
Distortion of the valve so it does not close properly
Incompetent or regurgitant valve: permits backward flow to occur when the valve should be closed
Valve Disorders
Mitral valve Disorders
Mitral valve stenosis
Mitral valve regurgitation
Mitral valve prolapse
Aortic Valve Disorders
Aortic valve stenosis
Aortic Valve Regurgitation

Factors Affecting Postnatal Pulmonary Vascular Development
Prematurity
Alveolar hypoxia
Lung disease
Congenital heart defects
Signs and Symptoms of Childhood Congenital Heart Disease
Symptoms associated with altered heart action
Heart failure
Pulmonary vascular disorders
Difficulty in supplying the peripheral tissues with oxygen and other nutrients

Types of Congenital Heart Defects
Patent Ductus Arteriosus
Atrial Septal Defects
Ventricular Septal Defects
Endocardial Cushion Defects
Pulmonary Stenosis
Tetralogy of Fallot
Transposition of the Great Vessels
Coarctation of the Aorta
Kawasaki Disease