Pericarditis

Definition and Classification

Definition

Pericarditis is an inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the pericardium Pericardium A conical fibroserous sac surrounding the heart and the roots of the great vessels (aorta; venae cavae; pulmonary artery). Pericardium consists of two sacs: the outer fibrous pericardium and the inner serous pericardium. The latter consists of an outer parietal layer facing the fibrous pericardium, and an inner visceral layer (epicardium) resting next to the heart, and a pericardial cavity between these two layers. Heart: Anatomy, the double-layered sac surrounding the heart.

Clinical classification is based on duration.

• Acute (< 6 weeks)
  • Fibrinous
  • Effusive (serous or serosanguinous)
• Subacute (6 weeks to 6 months)
  • Effusive-constrictive
  • Constrictive
• Chronic (> 6 months)
  • Constrictive
  • Adhesive (non-constrictive)

Epidemiology and Etiology

Epidemiology

• Reported in 0.1%–0.2% of hospitalized patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship
• Found in 5% of patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship admitted to the emergency department (ED) for nonischemic chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways

Etiology

Pathophysiology

• Inflammatory cascade stimulates the release of fluid in the pericardial space Pericardial Space Pericardial Effusion and Cardiac Tamponade, causing effusion.
• Rapid accumulation of large amounts of fluid in the pericardial space Pericardial Space Pericardial Effusion and Cardiac Tamponade can cause cardiac tamponade Cardiac tamponade Compression of the heart by accumulated fluid (pericardial effusion) or blood (hemopericardium) in the pericardium surrounding the heart. The affected cardiac functions and cardiac output can range from minimal to total hemodynamic collapse. Pericardial Effusion and Cardiac Tamponade, compromising cardiac output Cardiac output The volume of blood passing through the heart per unit of time. It is usually expressed as liters (volume) per minute so as not to be confused with stroke volume (volume per beat). Cardiac Mechanics and potentially resulting in obstructive shock Obstructive Shock Types of Shock.
• Constrictive pericarditis is characterized by a thickened and scarred pericardial sac that lies around the heart and prevents proper diastolic filling.

Clinical Presentation and Diagnosis

Typical clinical presentation

• Patient presents with central chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways that worsens during inspiration Inspiration Ventilation: Mechanics of Breathing or when lying flat. Leaning forward while sitting may relieve the pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways. 
• Fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever can be present. 
• In 50% of cases, a pericardial friction rub (scratching sound during systole Systole Period of contraction of the heart, especially of the heart ventricles. Cardiac Cycle and diastole Diastole Post-systolic relaxation of the heart, especially the heart ventricles. Cardiac Cycle) can be heard upon auscultation.

Etiology-specific features

• Viral or acute idiopathic Idiopathic Dermatomyositis pericarditis:
  • Chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways 1–2 weeks after a viral-like illness is suggestive.
  • Must exclude acute MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction, postcardiac injury, collagen Collagen A polypeptide substance comprising about one third of the total protein in mammalian organisms. It is the main constituent of skin; connective tissue; and the organic substance of bones (bone and bones) and teeth (tooth). Connective Tissue: Histology vascular disease, drugs, pyogenic pericarditis, etc ETC The electron transport chain (ETC) sends electrons through a series of proteins, which generate an electrochemical proton gradient that produces energy in the form of adenosine triphosphate (ATP). Electron Transport Chain (ETC).
  • Most frequent complication is relapsing pericarditis.
• Postcardiac injury acute pericarditis:
  • 1–4 weeks after a cardiac operation or blunt/penetrating trauma
• Tuberculous pericarditis:
  • Common cause of chronic pericardial effusion Pericardial effusion Fluid accumulation within the pericardium. Serous effusions are associated with pericardial diseases. Hemopericardium is associated with trauma. Lipid-containing effusion (chylopericardium) results from leakage of thoracic duct. Severe cases can lead to cardiac tamponade. Pericardial Effusion and Cardiac Tamponade in developing countries
  • In a patient with tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis or systemic illness and large cardiac silhouette: positive fluid culture or pericardial biopsy Biopsy Removal and pathologic examination of specimens from the living body. Ewing Sarcoma revealing caseating granuloma Caseating Granuloma Inflammation confirms the diagnosis.
• Uremic pericarditis:
  • Seen with severe renal failure Renal failure Conditions in which the kidneys perform below the normal level in the ability to remove wastes, concentrate urine, and maintain electrolyte balance; blood pressure; and calcium metabolism. Renal insufficiency can be classified by the degree of kidney damage (as measured by the level of proteinuria) and reduction in glomerular filtration rate. Crush Syndrome or in patients Patients Individuals participating in the health care system for the purpose of receiving therapeutic, diagnostic, or preventive procedures. Clinician–Patient Relationship on chronic dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Peritoneal Dialysis and Hemodialysis

Management

Viral or idiopathic Idiopathic Dermatomyositis pericarditis

• Oxygen and analgesia Analgesia Methods of pain relief that may be used with or in place of analgesics. Anesthesiology: History and Basic Concepts
• High-dose aspirin Aspirin The prototypical analgesic used in the treatment of mild to moderate pain. It has anti-inflammatory and antipyretic properties and acts as an inhibitor of cyclooxygenase which results in the inhibition of the biosynthesis of prostaglandins. Aspirin also inhibits platelet aggregation and is used in the prevention of arterial and venous thrombosis. Nonsteroidal Antiinflammatory Drugs (NSAIDs)/nonsteroidal anti-inflammatory drugs ( NSAIDs NSAIDS Primary vs Secondary Headaches) (e.g., ibuprofen Ibuprofen A nonsteroidal anti-inflammatory agent with analgesic properties used in the treatment of rheumatism and arthritis. Nonsteroidal Antiinflammatory Drugs (NSAIDs), indomethacin Indomethacin A non-steroidal anti-inflammatory agent (nsaid) that inhibits cyclooxygenase, which is necessary for the formation of prostaglandins and other autacoids. It also inhibits the motility of polymorphonuclear leukocytes. Nonsteroidal Antiinflammatory Drugs (NSAIDs)) plus gastric protection
• Adjuvant Adjuvant Substances that augment, stimulate, activate, potentiate, or modulate the immune response at either the cellular or humoral level. The classical agents (freund’s adjuvant, bcg, corynebacterium parvum, et al.) contain bacterial antigens. Some are endogenous (e.g., histamine, interferon, transfer factor, tuftsin, interleukin-1). Their mode of action is either non-specific, resulting in increased immune responsiveness to a wide variety of antigens, or antigen-specific, i.e., affecting a restricted type of immune response to a narrow group of antigens. The therapeutic efficacy of many biological response modifiers is related to their antigen-specific immunoadjuvanticity. Vaccination therapy with colchicine Colchicine A major alkaloid from colchicum autumnale l. And found also in other colchicum species. Its primary therapeutic use is in the treatment of gout. Gout Drugs enhances response and reduces the recurrence rate.
• Short-term glucocorticoids Glucocorticoids Glucocorticoids are a class within the corticosteroid family. Glucocorticoids are chemically and functionally similar to endogenous cortisol. There are a wide array of indications, which primarily benefit from the antiinflammatory and immunosuppressive effects of this class of drugs. Glucocorticoids can be used if NSAIDs NSAIDS Primary vs Secondary Headaches/ colchicine Colchicine A major alkaloid from colchicum autumnale l. And found also in other colchicum species. Its primary therapeutic use is in the treatment of gout. Gout Drugs are ineffective or contraindicated.

Constrictive pericarditis

• Complete pericardial resection (pericardiectomy) is the only definitive treatment and is best performed as early as possible
• Diuretics Diuretics Agents that promote the excretion of urine through their effects on kidney function. Heart Failure and Angina Medication to reduce symptoms leading to surgery

Specific treatments

• Initiation or intensification of dialysis Dialysis Renal replacement therapy refers to dialysis and/or kidney transplantation. Dialysis is a procedure by which toxins and excess water are removed from the circulation. Hemodialysis and peritoneal dialysis (PD) are the two types of dialysis, and their primary difference is the location of the filtration process (external to the body in hemodialysis versus inside the body for PD). Peritoneal Dialysis and Hemodialysis in addition to NSAIDs NSAIDS Primary vs Secondary Headaches in uremic pericarditis
• Antibiotics if an underlying infection is found
• Antituberculous therapy ± pericardiectomy

Differential Diagnoses

• Stable and unstable angina Unstable angina Precordial pain at rest, which may precede a myocardial infarction. Stable and Unstable Angina: paroxysmal chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways or discomfort caused by myocardial ischemia Myocardial ischemia A disorder of cardiac function caused by insufficient blood flow to the muscle tissue of the heart. The decreased blood flow may be due to narrowing of the coronary arteries (coronary artery disease), to obstruction by a thrombus (coronary thrombosis), or less commonly, to diffuse narrowing of arterioles and other small vessels within the heart. Coronary Heart Disease. Stable angina Stable angina Persistent and reproducible chest discomfort usually precipitated by a physical exertion that dissipates upon cessation of such an activity. The symptoms are manifestations of myocardial ischemia. Stable and Unstable Angina is characterized by a short duration of the complaints that are often associated with triggers like physical activity or stress. In unstable angina Unstable angina Precordial pain at rest, which may precede a myocardial infarction. Stable and Unstable Angina, symptoms are present even at rest. Most individuals with angina have coronary heart disease Coronary heart disease Coronary heart disease (CHD), or ischemic heart disease, describes a situation in which an inadequate supply of blood to the myocardium exists due to a stenosis of the coronary arteries, typically from atherosclerosis. Coronary Heart Disease.
• MI MI MI is ischemia and death of an area of myocardial tissue due to insufficient blood flow and oxygenation, usually from thrombus formation on a ruptured atherosclerotic plaque in the epicardial arteries. Clinical presentation is most commonly with chest pain, but women and patients with diabetes may have atypical symptoms. Myocardial Infarction: myocardial cell death Cell death Injurious stimuli trigger the process of cellular adaptation, whereby cells respond to withstand the harmful changes in their environment. Overwhelmed adaptive mechanisms lead to cell injury. Mild stimuli produce reversible injury. If the stimulus is severe or persistent, injury becomes irreversible. Apoptosis is programmed cell death, a mechanism with both physiologic and pathologic effects. Cell Injury and Death due to ischemia Ischemia A hypoperfusion of the blood through an organ or tissue caused by a pathologic constriction or obstruction of its blood vessels, or an absence of blood circulation. Ischemic Cell Damage of the myocardial tissue caused by a complete obstruction or drastic constriction of the coronary artery Coronary Artery Truncus Arteriosus. Typical symptoms include chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways that may radiate to the left arm Arm The arm, or “upper arm” in common usage, is the region of the upper limb that extends from the shoulder to the elbow joint and connects inferiorly to the forearm through the cubital fossa. It is divided into 2 fascial compartments (anterior and posterior). Arm: Anatomy, jaw Jaw The jaw is made up of the mandible, which comprises the lower jaw, and the maxilla, which comprises the upper jaw. The mandible articulates with the temporal bone via the temporomandibular joint (TMJ). The 4 muscles of mastication produce the movements of the TMJ to ensure the efficient chewing of food. Jaw and Temporomandibular Joint: Anatomy, neck Neck The part of a human or animal body connecting the head to the rest of the body. Peritonsillar Abscess, and upper back, as well as nausea Nausea An unpleasant sensation in the stomach usually accompanied by the urge to vomit. Common causes are early pregnancy, sea and motion sickness, emotional stress, intense pain, food poisoning, and various enteroviruses. Antiemetics and vomiting Vomiting The forcible expulsion of the contents of the stomach through the mouth. Hypokalemia. ST-elevation on ECG ECG An electrocardiogram (ECG) is a graphic representation of the electrical activity of the heart plotted against time. Adhesive electrodes are affixed to the skin surface allowing measurement of cardiac impulses from many angles. The ECG provides 3-dimensional information about the conduction system of the heart, the myocardium, and other cardiac structures. Electrocardiogram (ECG) can be present (STEMI) or absent (NSTEMI). 
• Aortic stenosis Stenosis Hypoplastic Left Heart Syndrome (HLHS): a narrowing of the aortic valve Aortic valve The valve between the left ventricle and the ascending aorta which prevents backflow into the left ventricle. Heart: Anatomy aperture, characterized by a narrowed left ventricular outflow tract and obstruction of blood flow Blood flow Blood flow refers to the movement of a certain volume of blood through the vasculature over a given unit of time (e.g., mL per minute). Vascular Resistance, Flow, and Mean Arterial Pressure into the aorta Aorta The main trunk of the systemic arteries. Mediastinum and Great Vessels: Anatomy
• Esophagitis Esophagitis Esophagitis is the inflammation or irritation of the esophagus. The major types of esophagitis are medication-induced, infectious, eosinophilic, corrosive, and acid reflux. Patients typically present with odynophagia, dysphagia, and retrosternal chest pain. Esophagitis: an inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the esophageal lining, which can be caused by gastroesophageal reflux disease Gastroesophageal Reflux Disease Gastroesophageal reflux disease (GERD) occurs when the stomach acid frequently flows back into the esophagus. This backwash (acid reflux) can irritate the lining of the esophagus, causing symptoms such as retrosternal burning pain (heartburn). Gastroesophageal Reflux Disease (GERD) ( GERD GERD Gastroesophageal reflux disease (GERD) occurs when the stomach acid frequently flows back into the esophagus. This backwash (acid reflux) can irritate the lining of the esophagus, causing symptoms such as retrosternal burning pain (heartburn). Gastroesophageal Reflux Disease (GERD)), infections Infections Invasion of the host organism by microorganisms or their toxins or by parasites that can cause pathological conditions or diseases. Chronic Granulomatous Disease, drugs, and allergic reactions Allergic Reactions Type I hypersensitivity reaction against plasma proteins in donor blood Transfusion Reactions.
• Pancreatitis Pancreatitis Inflammation of the pancreas. Pancreatitis is classified as acute unless there are computed tomographic or endoscopic retrograde cholangiopancreatographic findings of chronic pancreatitis. The two most common forms of acute pancreatitis are alcoholic pancreatitis and gallstone pancreatitis. Acute Pancreatitis: an inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the pancreas Pancreas The pancreas lies mostly posterior to the stomach and extends across the posterior abdominal wall from the duodenum on the right to the spleen on the left. This organ has both exocrine and endocrine tissue. Pancreas: Anatomy that typically causes epigastric pain Epigastric pain Mallory-Weiss Syndrome (Mallory-Weiss Tear) that radiates to the back 
• Pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia: acute or chronic inflammation Chronic Inflammation Inflammation of lung tissue most commonly caused by infection with bacteria Bacteria Bacteria are prokaryotic single-celled microorganisms that are metabolically active and divide by binary fission. Some of these organisms play a significant role in the pathogenesis of diseases. Bacteriology, viruses Viruses Minute infectious agents whose genomes are composed of DNA or RNA, but not both. They are characterized by a lack of independent metabolism and the inability to replicate outside living host cells. Virology, or fungi Fungi A kingdom of eukaryotic, heterotrophic organisms that live parasitically as saprobes, including mushrooms; yeasts; smuts, molds, etc. They reproduce either sexually or asexually, and have life cycles that range from simple to complex. Filamentous fungi, commonly known as molds, refer to those that grow as multicellular colonies. Mycology
• Pleuritis Pleuritis Pleuritis, also known as pleurisy, is an inflammation of the visceral and parietal layers of the pleural membranes of the lungs. The condition can be primary or secondary and results in sudden, sharp, and intense chest pain on inhalation and exhalation. Pleuritis: also known as pleurisy Pleurisy Pleuritis, also known as pleurisy, is an inflammation of the visceral and parietal layers of the pleural membranes of the lungs. The condition can be primary or secondary and results in sudden, sharp, and intense chest pain on inhalation and exhalation. Pleuritis, an inflammation Inflammation Inflammation is a complex set of responses to infection and injury involving leukocytes as the principal cellular mediators in the body’s defense against pathogenic organisms. Inflammation is also seen as a response to tissue injury in the process of wound healing. The 5 cardinal signs of inflammation are pain, heat, redness, swelling, and loss of function. Inflammation of the pleura Pleura The pleura is a serous membrane that lines the walls of the thoracic cavity and the surface of the lungs. This structure of mesodermal origin covers both lungs, the mediastinum, the thoracic surface of the diaphragm, and the inner part of the thoracic cage. The pleura is divided into a visceral pleura and parietal pleura. Pleura: Anatomy that lines the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy. May be caused by a viral infection (most common), pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, lung cancer Lung cancer Lung cancer is the malignant transformation of lung tissue and the leading cause of cancer-related deaths. The majority of cases are associated with long-term smoking. The disease is generally classified histologically as either small cell lung cancer or non-small cell lung cancer. Symptoms include cough, dyspnea, weight loss, and chest discomfort. Lung Cancer, autoimmune disease, or pulmonary embolism Pulmonary Embolism Pulmonary embolism (PE) is a potentially fatal condition that occurs as a result of intraluminal obstruction of the main pulmonary artery or its branches. The causative factors include thrombi, air, amniotic fluid, and fat. In PE, gas exchange is impaired due to the decreased return of deoxygenated blood to the lungs. Pulmonary Embolism 
• Tuberculosis Tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis: a disease caused by Mycobacterium tuberculosis Mycobacterium tuberculosis Tuberculosis (TB) is an infectious disease caused by Mycobacterium tuberculosis complex bacteria. The bacteria usually attack the lungs but can also damage other parts of the body. Approximately 30% of people around the world are infected with this pathogen, with the majority harboring a latent infection. Tuberculosis spreads through the air when a person with active pulmonary infection coughs or sneezes. Tuberculosis, which usually attacks the lungs Lungs Lungs are the main organs of the respiratory system. Lungs are paired viscera located in the thoracic cavity and are composed of spongy tissue. The primary function of the lungs is to oxygenate blood and eliminate CO2. Lungs: Anatomy but can also damage other parts of the body. Presents with fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, weight loss Weight loss Decrease in existing body weight. Bariatric Surgery, night sweats Night sweats Tuberculosis, and a productive cough
• Pneumothorax Pneumothorax A pneumothorax is a life-threatening condition in which air collects in the pleural space, causing partial or full collapse of the lung. A pneumothorax can be traumatic or spontaneous. Patients present with a sudden onset of sharp chest pain, dyspnea, and diminished breath sounds on exam. Pneumothorax: a collection of air in the pleural space Pleural space The thin serous membrane enveloping the lungs (lung) and lining the thoracic cavity. Pleura consist of two layers, the inner visceral pleura lying next to the pulmonary parenchyma and the outer parietal pleura. Between the two layers is the pleural cavity which contains a thin film of liquid. Pleuritis that causes the lung to collapse due to the loss of negative pressure. Presents with pleuritic chest pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, tachycardia Tachycardia Abnormally rapid heartbeat, usually with a heart rate above 100 beats per minute for adults. Tachycardia accompanied by disturbance in the cardiac depolarization (cardiac arrhythmia) is called tachyarrhythmia. Sepsis in Children, and reduced breath sounds on the ipsilateral side
• Herpes zoster Herpes Zoster Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Shingles (also known as herpes zoster) is more common in adults and occurs due to the reactivation of VZV. Varicella-Zoster Virus/Chickenpox: a dermatomal Dermatomal Dermatologic Examination rash Rash Rocky Mountain Spotted Fever with painful blistering, preceded by sharp burning pain Pain An unpleasant sensation induced by noxious stimuli which are detected by nerve endings of nociceptive neurons. Pain: Types and Pathways, caused by the reactivation Reactivation Herpes Simplex Virus 1 and 2 of the varicella-zoster virus Varicella-Zoster Virus Varicella-zoster virus (VZV) is a linear, double-stranded DNA virus in the Herpesviridae family. Varicella-zoster infections are highly contagious and transmitted through aerosolized respiratory droplets or contact with infected skin lesions. Varicella-Zoster Virus/Chickenpox. It usually affects dermatomes Dermatomes Spinal Cord: Anatomy T3 T3 A T3 thyroid hormone normally synthesized and secreted by the thyroid gland in much smaller quantities than thyroxine (T4). Most T3 is derived from peripheral monodeiodination of T4 at the 5′ position of the outer ring of the iodothyronine nucleus. The hormone finally delivered and used by the tissues is mainly t3. Thyroid Hormones through L3.