Cardiac Pathophysiology Part B - PowerPoint PPT Presentation

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Cardiac Pathophysiology Part B

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Most common cause is myocardial infarction. Myocarditis. Myocardopathies ... This causes dilation of the heart and increased preload. 9 ... – PowerPoint PPT presentation

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Title: Cardiac Pathophysiology Part B


1
Cardiac Pathophysiology Part B
2
Heart Failure
  • The heart as a pump is insufficient to meet the
    metabolic requirements of tissues.
  • Can be due to
  • dysfunction of the left ventricle
  • dysfunction of the right ventricle
  • or due to inadequate perfusion despite normal or
    elevated cardiac output

3
Classification of Heart Failure
  • Acute develops quickly
  • Chronic conditions gradually increase demands
    on the heart when the heart and circulatory
    system can no longer adapt the result is heart
    failure
  • Can lead to acute failure with excessive cardiac
    demand

4
Four broad consequences of heart failure
  • Congestion blood backs up
  • Activation of circulatory compensations
  • Cardiac output declines
  • Death

5
Types of Heart Failure
  • High output vs. Low output
  • High output
  • Anemia
  • Septicemia
  • Hyperthroidism (thyrotoxicosis)
  • Beriberi
  • Low output
  • Decreased pumping ability and cardiac output

6
  • Right-sided vs. Left sided Heart Failure
  • Right-sided HF
  • Most common cause is left heart failure
  • Can occur independently in primary lung disease
    conditions
  • COPD, ARDS, cystic fibrosis
  • Cor pulmonale
  • Left-sided HF
  • Decreased output to body
  • Blood backs up

7
Systolic vs. Diastolic HF
  • Systolic decreased contraction leads to
    decreased output and poor perfusion of tissues

8
Contractility is reduced by diseases that disrupt
myocyte activity
  • Most common cause is myocardial infarction
  • Myocarditis
  • Myocardopathies
  • When contractility decreases, stroke volume
    decreases, and left ventricular end-diastolic
    volume (LVEDV) increases.
  • This causes dilation of the heart and increased
    preload

9
Preload can also increase with excess plasma
volume
  • I.V. Fluid administration
  • Renal failure
  • Mitral valve disease
  • Increased LVEDV at first increases C.O., but over
    time can cause dysfunction of sarcomeres
    (stretched too far) and decreased contractility

10
Increased afterload is usually due to increased
peripheral resistance
  • Hypertension
  • Left ventricle works harder to overcome
    resistance, and hypertrophies.
  • Hypertrophy causes changes in the myocytes.
  • Also see deposition of collagen between myocyctes
    which can disrupt contractility and make
    ventricle more likely to dilate and fail.

11
Leads to increased blood pressure and pulmonary
congestion ?
  • Dyspnea
  • Orthopnea difficulty breathing in any position
    other than upright
  • Coughing up frothy sputum
  • Chest pain due to hypoxia at heart
  • Fatigue/confusion
  • Skin is pale, cold, sweaty
  • Pulse and lung sounds abnormal
  • Decreased urine output
  • Edema

12
Treatment is aimed at breaking the cycle of
decreasing contractility and increasing preload
and afterload.
  • Oxygen, nitrates and morphine improve
    myocardial oxygenation, help relieve coronary
    spasm while lowering preload through systemic
    vasodilation.
  • I.V. inotropic drugs such as dopamine or
    dobutamine increase contractility of the heart
    and can raise B.P. in hypotensive individuals.

13
  • Diuretics reduce preload
  • ACE inhibitors reduce preload and afterload by
    decreasing aldosterone levels and reducing
    peripheral venous resistance
  • Beta-blockers have been helpful in some people
  • Coronary by-pass
  • Salt restriction
  • Heart transplant

14
Diastolic Heart Failure
  • See symptoms and signs of heart failure, a
    preserved ejection fraction, and abnormal
    diastolic function
  • Accounts for 25 -40 of all cases of heart failure

15
Diastolic H.F. Results from
  • Decreased compliance of left ventricle and
    abnormal diastolic relaxation- results in
    increased pressure in ventricle at the end of
    diastole
  • Pressure is reflected back into the atrium and
    pulmonary circulation

16
Major causes
  • Hypertension induced myocardial hypertrophy and
    myocardial ischemia with ventricular remodeling
  • Aortic valvular disease
  • Mitral valvular disease
  • Cardiomyopathies

17
Signs and symptoms are similar to systolic heart
failure
  • Diagnosis made by echocardiography and heart
    cateterization

18
Management
  • Improve ventricular relaxation and prolong
    diastolic filling times to reduce diastolic
    pressure
  • Calcium channel blockers, beta-blockers, and ACE
    inhibitors have been used with success
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