Drugs of the Heart Part I

  1. Cardiovascular disorders
    1. Congestive heart failure (CHF)
    2. Cardiac arrhythmias
    3. Angina pectoris
    4. MI
    5. Hypertension or hypotension
    6. Shock
  2. Drug classes
    1. Vasopressors
    2. Inotropes
    3. Vasodilators
    4. Antiarrhythmia
      1. Tachycardia
      2. Bradycardia
    5. Electrolytes
    6. Anti-thrombotic
    7. Sedatives and paralytics
    8. Pain management
    9. Sepsis
  3. Associated terms you should know
    1. CO (CO) = Heart Rate x stroke volume
    2. Preload – Volume coming in - filling pressures of the cardiac chambers
    3. Afterload – Volume going out - resistance
    4. Contractility – result in ejection fraction (EF)
  4. Terms associated with cardiac medication
    1. Inotropic – affects contractility
    2. Chronotropic – affects heart rate (increase or decrease)
      1. Positive chronotropic drugs increase heart rate
      2. Negative chronotropic drugs decrease the heart rate
    3. Dopaminergic – may increase urine output and mesenteric vasodilation
  5. Receptors in the heart - Two basic types alpha α and β
    1. Alpha
      1. Found in vascular smooth muscle and heart muscle
      2. Two types
        1. Alpha 1
          1. Vasoconstriction of smooth muscle
          2. Increases Inotropic
          3. Decreases chronotropic
        2. Alpha 2
          1. Prevents release of norepinephrine
          2. Counters alpha 1
          3. Modulates vascular tone of large vessels
        3. Alpha effects
          1. Increases blood flow to brain, heart, and skeletal muscles
          2. Increases cellular metabolism
          3. Increases O2 consumption and CO2 production
          4. Causes pupil dilation
      3. Beta
        1. Found in vascular smooth muscle and heart
        2. Two types
          1. Beta 1
            1. Increases chronotropic and decreases Inotropic
            2. Increases conduction
            3. Found mostly in heart tissue
          2. Beta 2
            1. Vasodilation of smooth muscle
            2. Relaxes bronchioles and gut smooth muscles
            3. Found mostly in bronchioles and gland cells
          3. Overall effect
          4. Increases heart rate and contractility
          5. Increases sweat production
          6. Decreases GI tone and motility
          7. Causes urinary retention
          8. Causes bronchial relaxation
  6. Specific Drugs that effect the heart - There are 5 general categories
    1. Vasopressors (Category I)
      1. Characteristics
        1. Maintain tissue perfusion by keeping the systolic pressure @ 90 mmHg
        2. Note:  60 mmHg required to keep all major organs perfused, but the brain needs 70 mmHg
        3. Affects patient’s fight or flight response
        4. If the patient electrolytes are low, low blood volume, and/or acidosis this drug will be less effective
        5. Tissue necrosis occurs if injected subcutaneously
        6. Increases O2 supply to cardiac tissue (MVO2)
        7. There are 5 different drugs in the category
      2. Vasopressin
        1. Alternative to epinephrine
        2. Potent peripheral vasoconstrictor
        3. Lasts 2 – 8 hours
      3. Epinephrine (Adrenalin)
        1. Effects both Alpha and Beta receptors
        2. Heart becomes more responsive to fibrillation
        3. Stimulates pacemaker activity and conductivity in cardiac resting state
        4. Immediate treatment for anaphylaxis or any hypersensitive response
        5. Dose can be given initially during cardiac rest and then IV drip as needed
      4. Norepinephrine (Levophed)
        1. Effects Alpha significantly more than Beta receptors
        2. Causes vasoconstriction and decreases renal, visceral, and skeletal blood flow
        3. Used on patients that have:  hypotensive states, cardiogenic and septic shock
        4. Dose is best given through a central line
        5. Is not a first line drug
      5. Dopamine (Intropin)
        1. Pending dose level it effects Alpha and Beta receptors, dopaminergically
        2. Low dose should no longer be used (2-3 mcg/kg/min)
        3. Moderate dose 5-10 mcg/kg/min -Stimulates beta receptors to increase:  HR, contractility, BP, and CO
        4. High Dose:  10-20 mcg/kg/min - Beta activity remains and Alpha activity is overwhelmed by Dopaminergic actions
        5. Above results cause vasoconstriction
        6. Indication:  hypotension (not volume related), shock, septicemia, CHF
        7. Usually a first line drug
      6. Phenylephrine (Neosynephrine)
        1. Alpha 1 stimulant causing vasoconstriction (does not effect the heart)
        2. Reduces renal and mesenteric blood flow, which limits its long term use
        3. Used in short-term management of hypotension or septic shock
      7. Side effects of Vasopressors
        1. May cause ventricular dysrhythmias
        2. Palpitations and tachycardia are possible
        3. Hypertension
        4. Angina
        5. Decreased urinary output
        6. Headaches are common
    2. Inotropics (Category 2)
      1. Characteristics
        1. Increases the force of myocardial contraction
        2. Major role in the clinical treatment of CHF
      2. Dobutamine (Dobutrex)
        1. Works mostly on Beta 1 receptors
        2. Mild effect on Beta 2 receptors
        3. Increases contractility, effecting the stroke volume, and CO with little effect on heart rate
        4. Increases coronary blood flow and MVO2
        5. Due to the increase in CO causes increase in blood supply to peripheral areas and the kidneys
        6. First line drug
      3. Indicators
        1. Heart failure
        2. Cardiogenic shock
        3. Low CO states: RV infarcts and LV failure
      4. Side effects
        1. Palpitations and/or tachycardia
        2. Arrhythmias
        3. Angina
        4. Hypertension
      5. Milrinone (Primacor)
        1. Phosphodiesterase inhibitor without adrenergic effect - prolong and enhances the effects of physiological processes mediated by these cyclic nucleotides. cAMP and cGMP
        2. Analog to amrinone (vasodilator) with similar actions, but more effective and fewer side effects
        3. Positive inotropic and causes vasodilator
        4. Indications
          1. CHF
          2. Low cardiac output (for whatever reason)
        5. Side effects
          1. Hypotension
          2. Angina/arrhythmias
          3. Thrombocytopenia
          4. Sulfite allergy (amrinone only)
      6. Isoproterenol (Isuprel)
        1. Action
          1. Stimulates beta 1 and 2
          2. Potent inotropic and chronotropic
          3. Stimulates heart, dilates vessels in skeletal muscles, and relaxes bronchial smooth muscles
        2. Indications
          1. Transplants and pediatrics
          2. Might be used in cardiogenic shock except if caused by MI
          3. Respiratory drug for bronchospasm
        3. Side effects
          1. Proarrrhythmia – antiarrhythmic that causes new arrhythmias which may result in V-Tack
          2. Palpitations and angina
          3. Headache and anxiety
          4. Hypotension
      7. Digoxin (Lanoxin)
        1. Action
          1. Increases myocardial contractility
          2. Reduces heart rate
        2. Side effects
          1. Excess amount may cause toxicity
          2. Symptoms include:  nausea, vomiting, anorexia, blurred or yellow vision, fatigue, bradycardia, and heart blocks
          3. Imbalances of K, Mg, and Ca increase the toxic effect
      8. Digibind (Digoxin immune Fab)
        1. Used to eliminates the toxic effect of digoxin
    3. Peripheral Vasodilators (Category 3)
      1. Characteristics
        1. Relaxation of smooth muscles in blood vessels
        2. May decrease BP
        3. Increases CO by reduces blood flow (afterload reduction)
      2. Nitroglycerin (Tridil)
        1. Action
          1. Veno/arterial dilation
          2. Decreases venous return, preload, MVO2, BP, CVP, PCWP
          3. Improves coronary artery flow and O2
        2. Indications
          1. Angina and/or MI
          2. HTN
          3. CHF
          4. Preload/afterload reduction
        3. Side effects
          1. Hypotension
          2. Headache and dizziness
          3. Bradycardia or reflex tachycardia
      3. Na Nitroprusside (Nipride)
        1. Action
          1. Dilates venous and arterial smooth muscles
          2. Reduces BP and PVR
          3. Initially decreases afterloading and also decreases preload
        2. Indications
          1. Hypertensive crisis
          2. Afterload reduction – CHF, cardiogenic shock, and LV failure
        3. Side effects
          1. Hypotension
          2. Thiocyanate toxicity
          3. Reflex tachycardia
          4. Angina
      4. Fenoldopam (Corlopam)
        1. Action
          1. Decreases PVR
          2. Increases renal blood flow, diuretics, and attributes
          3. Is an agonist to dopamine
        2. Indications
          1. HTN
          2. Renal Compromise
          3. CHF
      5. Nesiritide (Natrecor)
        1. Action
          1. Form of human B-type natriuretic peptide hBNP)
          2. Relaxes smooth muscles
          3. Acts as a vasodilator, diuretic, natriuretic, and causes dose dependency
        2. Indications
          1. Acutely decompensates CHF patients that have dyspnea at rest or with minimal activity 
          2. Do not use with patient on NTG or Nipride
        3. Side effects
          1. Hypotension
          2. Renal Dysfunction
          3. Ventricular arrhythmias
          4. Angina
          5. Bradycardia
          6. Headache

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