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Cardiovascular Physiology Lecture 9 (Objective 1: Understand the meaning…

- - - - 2:1 ratio of conduction between atria and ventricles
        1/2 of atrial beats conducted to ventricle
        Av node= frequency filter, many of atrial impulses reach AV node during its refractory period.
        This protects the ventricles from dangerously high rates that compromise CO
- - - - Mitral Regurgitation
        
        During Ventricular contraction the AV valves remain closed to prevent backflow. Mitral regurgitation blood flows back into atria (leaky)
        ->leads to high LA pressure -> pulmonary edema
        -> CO is reduced because portion of SV is ejected back into LA
- - - - Increase SNS activity
        -Increase contractility and HR to maintain CO
        -Increase TPR to maintain MAP
      - Actually detrimental in long term...
        Leads to downregulation and desensitization of beta-adrenergic receptors
      - Augmented EDV (preload) to maintain SV via Frank-Starling mechanism
      - Best treatment: "get a new pump" (heart transplant, mechanical assist device, regenerative therapy?)
- - - - Essential Hypertension:
        -Cardiac output is usually normal
        -Appears to be associated with increased peripheral resistance
      - Consequences:
        Afterload= the "load" that the heart must overcome to eject blood (arterial BP is used as indirect indicator)
      - Carotid and aortic baroreceptors adapt: allows higher BP to persist with correction by autonomic nervous system
        Kidneys are complicit: BP elevations could be corrected by decreasing blood volume (via increased urine output by kidneys)
        Treatment: reduce TPR/blood volume?
        -Calcium channel blockers, diuretics, beta-blocking drugs, ACE inhibitors, and angiotensin receptor blockers
  - - - Can compromise blood flow throughout the body
        Coronary Artery Disease
        Cerebrovascular Disease
        Peripheral Arterial Disease
        
        Treatment:
        Cardiac Catheterization= moves opposite direction of blood flow. Inserted at femoral artery.
        Coronary Artery Bypass Graft (CABG) Surgery:
        Bypass using an artery from another tissue, alternative path for blood to flow. Can do it with a vein or artery.
        Coronary Stenting to Restore Vessel Diameter (Angioplasty):
        Balloon catheter inserted between stenosis.