MS week 1

• The heart is a cone-shaped hollow muscular organ located in the mediastinum between the lungs
• The heart pumps about 60ml/beat or 5L/min
• Three layers of the heart:

  • Endocardium: innermost layer consisting of endothelial tissue, lining the inside of the heart and valves
  • Myocardium: middle layer made up of muscle fibers, responsible for the pumping action
  • Epicardium: outermost layer that can accumulate fluid
• Mechanical structure of the heart:

  • Chambers: Right atrium, Right Ventricle, Left Atrium, Left Ventricle
  • Valves: AV Valves, Semilunar valves
• Blood flow in the heart follows this order: Body (unoxygenated blood), inferior/superior vena cava, right atrium, tricuspid valve, right ventricle, pulmonary arteries (unoxygenated blood), lungs, pulmonary veins (oxygenated blood), left atrium, mitral or bicuspid valve, left ventricle, aortic valve, aorta, body
• Coronary arteries supply blood to the heart muscles
• Electrophysiologic properties of the heart:

  • Automatically initiate an impulse spontaneously and repetitively
  • Excitability (depolarization) responds to a stimulus
  • Conductivity transmits electrical impulses
  • Contractility contracts
  • Refractoriness inability to respond until repolarization
• Conduction system of the heart:

  • SA node (pacemaker)
  • AV node
  • Bundle of His
  • R & L bundle branches
  • Purkinje fibers
• Sequence of events during the cardiac cycle:

  • Systole (contraction) - emptying
  • Diastole (relaxation) - filling
• Disturbances in the pumping mechanism of the heart:

  • Cardiac infections
  • Ineffective Endocarditis: infection/inflammation of the inner layer of the heart
• Types of Ineffective Endocarditis:

  • Acute Ineffective (Onset 0-4 days)
  • Sub-acute Ineffective (Onset 5-15 days)
• Risk factors for Ineffective Endocarditis:

  • Recent heart surgery
  • Prosthetic valves
  • High flow valvular diseases
  • Intravenous drug use
  • Dental surgery
• Three classes of patients to be considered for Ineffective Endocarditis:

  • Those with congenital heart disease
  • Those with prosthetic valves
  • Intravenous drug users
• Causative agents for Ineffective Endocarditis:

  • Staphylococcus and Streptococcus infections
  • Prosthetic valves - Staphylococcus epidermidis
  • Intravenous drug users - Staphylococcus aureus (MRSA causative agent)
• Clinical manifestations of Ineffective Endocarditis:

  • Fever
  • Roth spots
  • Osler’s nodes
  • Murmur
  • Janeway lesions
  • Acute glomerulonephritis
  • Nail-bed hemorrhage
  • Embolism
• Management of Ineffective Endocarditis:

  • Emergent care: Tend to airway, breathing, and circulation
  • Obtain blood culture
  • Transthoracic echocardiogram
  • Basal Metabolic Panel
  • Empiric antibiotics: Vancomycin & Gentamycin
• Basal Metabolic Panel (BMP) measures levels of components in the blood important for maintaining normal body functions
• Transthoracic Echocardiography is a noninvasive test to scan the heart
• Complications of Ineffective Endocarditis:

  • Congestive Heart Failure
  • Systemic Embolization
• Prophylaxis for Endocarditis:

  • To prevent development of endocarditis
  • Who: Patients with prosthetic heart valves, previous endocarditis, heart valve repair, unrepaired cyanotic heart disease
  • When: Before dental procedures causing bleeding or manipulating oral/respiratory mucosa
  • How: Amoxicillin or 3rd generation cephalosporins
• Pericarditis is an infection or inflammation of the pericardium
• Causes of Pericarditis:

  • Infective: Viral, TB infections
  • Non-infective: Uremia, Trauma, Lupus, Post-MI, Idiopathic
• Assessment of Pericarditis includes symptoms of positional and pleuritic chest pain
• Symptoms of pericarditis:

  • Positional and pleuritic chest pain that is better when upright and worse when in supine
  • May be febrile
  • May have hemodynamic instability if tamponade is present
• Signs of pericarditis:

  • Physical examination is unremarkable
  • Pericardial friction rub
  • May have muffled heart sound if tamponade is present
  • Pulsus paradoxus (decreased BP during inhalation)
• Best initial step in any patient with chest pain: EKG/ECG

  • EKG result showing diffuse ST elevation + PR segment depression in lead II is a pathognomonic sign
  • Echocardiogram may show normal LV wall motion
  • Other labs to consider: Basic Metabolic Parameters, Cardiac Enzyme Profile, CBC
• Purpose of cardiac enzyme test:

  • Measure specific biological markers in blood
  • High levels of cardiac enzymes can indicate heart attack or other heart problems
  • Also known as cardiac biomarkers
• Treatment for pericarditis:

  • Drug of choice: NSAIDs and colchicine + systemic corticosteroids to decrease inflammation
  • Consider Pericardiocentesis if pericardial effusion is present
• Causes of myocarditis:

  • Infective causes: Coxsackie virus, Trypanosoma cruzi, Trichinella, Lyme disease, Toxoplasma gondii
  • Non-infective causes: SLE (lupus), Hypothyroidism, Polymyositis, Drug-induced/Drug-associated, Giant-cell
• Clinical manifestations of myocarditis:

  • Arrhythmias
  • Positional chest pain
  • CHF-like symptoms
  • Dyspnea
  • Fatigue
  • Cough
  • Palpitations
  • Edema
• Types of heart failure:

  • Systolic Heart Failure: heart can't pump hard enough, leading to congestion in the lungs
  • Diastolic Heart Failure: heart can't fill enough, leading to congestion in the lungs
• Systolic Heart Failure:

  • Decreased ejection fraction of the heart less than 40%
  • Ejection fraction can be computed by Stroke Volume / End Diastolic Volume
  • Normal ejection fraction is 50-70%
• Diastolic Heart Failure:

  • Caused by abnormal filling of the ventricles
  • Reduced "preload"
  • Ejection fraction may be normal due to decrease in ventricle size
• Causes of Left-Sided Heart Failure:

  • Ischemic heart disease, Long-standing hypertension, Dilated cardiomyopathy, Concentric hypertrophy, Restrictive cardiomyopathy
• Clinical manifestations of Left-Sided Heart Failure:

  • Pulmonary edema, Increased pulmonary artery pressure, Dyspnea, Orthopnea, Crackles or Rales upon auscultation
• Causes of Right-Sided Heart Failure:

  • Atrial and Ventricular septal defect, Chronic lung disease, Cor pulmonale
• Clinical manifestations of Right-Sided Heart Failure:

  • Concentric hypertrophy, Ascites, Hepatosplenomegaly, Pitting edema
• Treatment and Management of Heart Failure:

  • Positioning (high, low, or semi-fowlers, sitting, upright, or neutral position)
  • Oxygen support
  • Drugs: ACE inhibitors, Diuretics, Digoxin
  • Monitoring for potential side effects and complications