Cardiac System

  1. Describe the physiology of cardiac contraction
    • Current originates in SA node
    • Spreads through atrial bundles to AV node
    • AV node has slight delay allowing for atrium to completely contract/empty before depolarization continues
    • current spreads through His bundle & simultaneously travels through left & right bundles, allowing both sides of the ventricle to contract at the same time
  2. Explain the P-QRS-T deflections
    • P: atrial (muscle) depolarization
    • QRS: ventricular (muscle) depolarization
    • T: ventricular (muscle) depolarization
  3. Applications for ECG
    • Heart rate
    • Heart rhythm & conduction
    • Cardiac chamber enlargement (specific but not sensitive)
    • CAN NOT tell you about CHF or quality of contraction
  4. 4 steps to evaluating ECG
    • Evaluate for artifacts, quality, calibrations
    • Determine heart rate
    • Evaluate P-QRS-T complex configurations & morphologies
    • Name the cardiac rhythm
  5. Jugular pulse indications
    • Elevated right heart filling pressure
    • Possibly obstruction to filling of right heart
  6. Causes of jugular pulsations
    • Tricuspid insufficiency
    • Hypertrophied/stiff right ventricle (pulmonic stenosis, pulmonary hypertension)
    • Certain arrhythmias (complete heart block)
  7. Causes of jugular distension (+/- pulsation)
    • Occlusion of the cranial vena cava (external pressure, mass, thrombosis)
    • Very high right heart filling pressure (severe pericardial effusion)
  8. Causes of shifted precordial impulse (to the right)
    • Cardiac enlargement
    • Mass lesions displacing heart
    • Collapsed lung lobes allowing cardiac displacement
    • Focal accumulations of air or fluid
  9. Causes of decreased intensity of precordial impulse
    • Obesity
    • Pleural effusion
    • Pericardial effusion
    • Weak cardiac contractions
    • Thoracic masses
    • Pneumothorax
  10. Causes of hyperkinetic pulses
    • Wide separation between systolic & diastolic arterial pressure
    • High adrenergic tone, PDA, aortic regurgitation
  11. Causes of hypokinetic pulses
    • Reduced stroke volume or narrower pulse pressure
    • Heart failure, hypovolemia, some arrhythmias
  12. Causes of pulse deficits
    • Fewer femoral pulses than palpable or auscultable
    • Arrhythmia (VPCs)
  13. Causes of turbulent blood flow
    • Increased velocity (narrowed vessels, damaged valves, shunting paths)
    • Decreased viscosity (anemia)
  14. Reynolds number
    • Used to calculate turbulence of blood flow
    • High numbers = louder sounds
    • RN = RVD / v where R=radius, V=velocity, D=density, v=viscosity
  15. Common causes of heart murmurs
    • Abnormal pathways of flows (shunts)
    • Valvular pathology (stenosis, insufficiency)
    • Decreased viscosity (anemia)
    • Large diameter vessels (horses, cows)
  16. Heart Sounds
    • S1: closing of AV valves
    • S2: closure of aortic/pulmonic valves
    • S3: rapid ventricular filling
    • S4: atrial contractions
    • Systolic click: mid-late systole AV valve due to delayed closure or prolapse of valve
  17. Gallop rhythm
    • S3 gallop = dilated ventricles (DCM)
    • S4 gallop = secondary to ventricular hypertrophy (HCM)
  18. Systolic clicks
    Most commonly heard with early endocardiosis of the mitral valve
  19. Differentials for a continuous left base murmur
  20. Differentials for a systolic ejection left base murmur
    • Subaortic stenosis
    • Pulmonic stenosis
  21. Differentials for a diastolic blowing left base murmur
    • Aortic regurgitation
    • Sometimes subaortic stenosis or ventricular septal defect
  22. Differentials for systolic ejection left apex murmur
    • Early mitral regurgitation
    • Subaortic stenosis
  23. Differentials for systolic plateau left apex murmur
    • Mitral regurgitation
    • Endocardiosis/Endocarditis
    • DCM
  24. Differentials for systolic ejection right apex to sternum murmurs
    Ventricular septal defect
  25. Differentials for systolic plateau right apex to sternum murmurs
    • Tricuspid regurgitation
    • Endocardiosis
    • Tricuspid regurgitation secondary to pressure overload (pulmonary hypertension, PS, congenital valve dysplasia)
  26. Diseases that may not have murmurs
    • Tetrology of Fallot
    • Cardiomyopathies
    • Pericardial effusion
    • Pulmonary hypertension
    • Systemic hypertension
    • Arrhythmias
  27. Thoracic radiography
    Localizes problem
Card Set
Cardiac System
Internal medicine cardiac