Lecture 12 Heart Defects

From Iusmphysiology

(Difference between revisions)
(Created page with '*continued here from Lecture 11 Fetal Physiology on 01/31/11 at 11:25AM. ==Congenital and Acquired Heart Anatomical Abnormalities== ===Objectives=== *The diagnosis of most …')
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*A. Aortic regurgitation
*A. Aortic regurgitation
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'''*B. Aortic stenosis'''
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*B. Aortic stenosis
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**"A noisey stenotic aortic valve that the lady has compensated with a high vascular resistance"
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*C. Mitral regurgitation
*C. Mitral regurgitation
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*D. Mitral stenosis
*D. Mitral stenosis
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*E. Mitral valve prolapse
*E. Mitral valve prolapse
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===Clinical case===
===Clinical case===
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*A. loss of papillary muscle function in the right ventricle.
*A. loss of papillary muscle function in the right ventricle.
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*'''B. loss of papillary muscle function in the left ventricle.'''
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*B. loss of papillary muscle function in the left ventricle.
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**"loss of papillary muscle function in the left ventricle. Location of murmur fits plus timing fits."
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*C. a clot obstruction of the aortic valve.
*C. a clot obstruction of the aortic valve.
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*D. a clot obstruction of the mitral valve.
*D. a clot obstruction of the mitral valve.
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*E. a transmural breakdown of the left ventricular wall infarct.
*E. a transmural breakdown of the left ventricular wall infarct.
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Revision as of 15:26, 7 February 2011

Contents

Congenital and Acquired Heart Anatomical Abnormalities

Objectives

  • The diagnosis of most heart abnormalities begins with the stethoscope and a knowledge of the heart cycle. For each of the abnormalities studied, when would a murmur be heard during the heart cycle and over which valve, if a valve is involved?
  • In the six abnormalities studied, which would have enlarged end diastolic volumes? In each situation, why is the EDV enlarged?
  • In the six abnormalities studied, which would have reduced end diastolic volumes? In each situation, why is the EDV reduced?

Statistics

  • 9 of every 1000 live births has a heart defect that requires intervention.
  • 1.7 of every 1000 children develops type 1 diabetes
  • So cardiac abnormalities are far, far more common than T1DM.


  • We do a ton of cardiac procedures (procedure, cost, death rate):
    • Not cheap
    • Coronary Artery Bypass Graft, $85,653, 2.1%
    • Angioplasty Procedure, $44,110, 0.8%
    • Diagnostic Catheterization, $25,322, 0.9%
    • Pacemaker, $43,101, 0.9%
    • Implantable Defibrillator, $99,845, 0.8%
    • Valves/Septal Defect, $119,918, 5.1%
    • Cardiac catheterizations
      • Much less expensive than surgeries
      • 1.3 million!
      • Mostly for coronary artery disease
      • Many of these are done in children to detect problems.


  • We do a ton of open heart surgeries, too:
    • Valve replacements: 106,000
    • Bypass (cardiac revascularization): 469,000
    • Heart transplant: 2,192
    • Septal Defects: 124,000
    • Total open-heart procedures: 699,000

Atrial septal defect

  • Atrial septal defect is the second most common congenital heart defect.
  • Often there is a physical hole between the atrial other than the foramen ovale.
  • Can sometimes be repaired with a patch.
  • Once fixed, pt is able to grow bigger and strong and to exercise much more strenuously.
  • Atrial septal defects allow movement of blood from the left atrium to the right atrium because blood pressure is higher in the left atrium.
  • S&S:
    • There isn't usually hypoxia at rest
      • Because blood is passing left to right
      • However, the systemic loop will have less capacity to exercise, etc.
    • The heart is limited to normal or moderate exercise because it is getting less blood than it needs for extreme exercise.
    • Causes increased pulmonary blood pressure because of high right ventricular output (because right atrium is extra full because left atrium donated some extra).
      • Increased bp in the pulmonary circuit can generate hypertrophy of the arterial vascular muscle.
      • Because oxygenated blood is getting pushed to the lungs, they contract slightly causing increased pulmonary resistance.
    • Pulmonary hypertension (see two points above)
    • Right ventricular chamber may enlarge (in response to higher preload)
    • Right ventricular muscular hypertrophy
    • Heart sounds may be generated:
      • Diastolic murmur as blood is pushed form left atrium to right atrium,
        • This is a soft sound or may not be audible at all.
      • 3rd or 4th heart sound because of right ventricle's stretched state,
      • Louder pulmonary valve sound because of higher pulmonary pressure,
      • Splitting of second heart sounds because the right ventricle takes longer to pump against an increased afterload.
    • Right ventricular failure, eventually.

II. Ventricular Septal Defect

  • The ventricular septum is complicated
    • It is solid muscle
    • It is weaved together like a basket
    • If not weaved just correctly, there can be opening form one ventrical to the next.
    • There is also a dense connective tissue at the top of each ventricle that if not well connected can allow passage of blood.
  • These defects can be really big causing a large load on the ventricle.
  • Ventricular septal defect is the most common congenital cardiac defect.
  • This is a hole between the two ventricles.
  • Small defects tend to close spontaneously in chidlren.
  • 75% of cases require surgery before the age of 5.
  • Causes all the same problems as atrial defect.
  • In addition, if the hole is large enough, there will be increased work required by the left ventricle.
  • S&S:
    • Ventricular systole murmur volume is indirectly proportional to the area of the hole.
    • Left ventricle is overstretched and fails.
    • Risk of endocarditis is increased because of shear flow over edges of shunt.
      • This can generate clots on the septum that get washed into the coronary arteries, the brain, the gut, the respiratory tract, etc.

III. Semilunar valve stenosis

  • With semilunar valve stenosis there is a problem with ventricular ejection because the aortic or pulmonary valves are stiffened.
  • Recall that work is the stroke volume multiplied by the pressure (W = SV * P).
  • When the valve is stiff, it increases the work the ventricles must do to eject the blood.
  • S&S:
    • Ventricular hypertrophy to maintain cardiac output in light of increased work demand
    • EDV is increased by the ejection fraction is below normal.
    • Venous pressure (and therefore atrial pressure) are elevated because of ventricular pressure overload. (That is, venous pressure goes up because the ventricle must reach a higher systolic pressure to get blood through the stenosed valve.)
    • Systolic murmur is audible because the blood turbulantly rushes around the stenosed valve.

IV. Semilunar valve insufficiency

  • In this situation the valve is causing pressures in the ventricle to be abnormally high.
  • This increase in pressure causes "over-distension".
    • "distention: the act of expanding by pressure from within" per wordnet
  • In this pathology, during systole, blood flows out of the ventricle, through the valve but then some returns to the ventricle during diastole.
  • Recall that work is the stroke volume multiplied by the pressure (W = SV * P)
  • Before we could replace valves, we sometimes knicked stenosed valves with a knife to make them an insufficient valve for which the heart can better compensate.
  • S&S:
    • The ventricular chamber will expand and the ventricle will hypertrophy but not to the extent seen in stenosis.
    • EDV will increase and the ejection fraction will be increased, however, the effective stroke volume that actually stays in the aorta may be below normal.
    • Arterial and venous pressures will rise because ventricular volume overload
    • A diastolic murmur will be heard as the blood moves backward through the valve during diastole.
      • Like a flag in the wind; constant throughout diastole.


  • stopped here on 01/31/11 at 12PM.


V. Atrioventricular stenosis

  • In this pathology, blood has difficulty entering the ventricle from the atrium.
  • Recall that work is stroke volume times pressure (W = SV * Pressure)
  • With AV stenosis the ventricle does not fill properly so the EDV is low.
  • S&S:
    • The ventricle may become smaller than normal.
      • This results because of a low SV and the ventricle being under worked.
    • EDV is decreased by ejection fraction is increased.
    • Atrial and venous pressure are elevated because of AV valve resistance.
    • Diastolic murmur is heard as blood must be forced through the AV valves.
    • 3rd and 4th heart sounds may also be heard

VI. Atrioventricular insufficiency

  • AV insufficiency allows blood to flow backward form the ventricle to the atrium
  • The ventricle ends up being overworked because it has to generate more pressure over a larger volume in order to generate the correct output in spite of the fact that some of its effort is spent on pushing blood back into the atrium.
  • S&S:
    • Ventricular chamber enlarged and hypertrophied
    • EDV is elevated, ejection fraction is elevated, however, the effective stroke volume is decreased
    • Arterial and venous pressure are increased because of back flow from the ventricular systole
    • Systolic murmur can be heard as blood moves into the atrial during ventricular systole (3/4th sound)

Clinical case

  • 45 yo f
  • bicuspid aortic vavle
  • A. Aortic regurgitation

*B. Aortic stenosis

    • "A noisey stenotic aortic valve that the lady has compensated with a high vascular resistance"
  • C. Mitral regurgitation
  • D. Mitral stenosis
  • E. Mitral valve prolapse

Clinical case

  • 87 yo f
  • A. loss of papillary muscle function in the right ventricle.
  • B. loss of papillary muscle function in the left ventricle.
    • "loss of papillary muscle function in the left ventricle. Location of murmur fits plus timing fits."
  • C. a clot obstruction of the aortic valve.
  • D. a clot obstruction of the mitral valve.
  • E. a transmural breakdown of the left ventricular wall infarct.
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