Medical Pharmacology Chapter 43:  Adult Cardiac Procedures

 Valvular Disease and Ventricular Function Analysis

• Cardiac Catherization

  •  Ventricular pressure, volume, ejection fraction information

  •  Pulmonary pressures/resistances

  •  Valvular luminal area estimates

  •  Evaluation of shunts and determination of shunt flow magnitude

  •  Determination of cardiac output and vascular resistance

Hemodynamic Status

• Hemodynamic Status Assessment based on:

  1.  Focused historical interview (patient interview)

     • History of myocardial infarction; intermittent/chronic congestive heart failure

       • Congestive heart failure symptoms

         1. fatigue

         2. dyspnea on exertion

         3. orthopnea

         4. paroxysmal nocturnal dyspnea

         5. ankle swelling

  2.  Physical exam (including evaluation  of laboratory tests)

     •  Hypotension/tachycardia (severe congestive failure)

     •  Laterally displaced apical impulse

     •  Prominent neck veins

     •  Normal

     •  S₃ heart sound  

     •  S₄ heart sounds  

     •  Rales

     • Pitting edema

     • An understanding of how current the information is.

     •  Recognizing that certain factors have not yet been assessed, e.g. labile hypertension or arrhythmias.

      

• Most Important Issue: Presence of heart failure (compensated or not): The major factor affecting surgical outcome:

  • Heart failure may influence

    •  Anesthetic and related drug choices

    •  Hemodynamic monitoring approaches

  • Severe heart failure results in patient in distress at rest (orthopneic short of breath, excesses sympathetic tone (pale, cold to the touch)): manage intraoperatively with significant caution because of limited cardiac reserve (poor ventricular function)

  •  Indications of poor ventricular function

    •  Enlarged Heart

    •  Gallop rhythm: S₃ heart sound, indicative of congestive heart failure (decompensation)

    •  Veins: venous distention/engorgement; hepatojugular reflux

    •  Edema: peripheral swelling; hepatomegaly; pneumonia; recurrent bronchitis, rales

    •  Hypoperfusion-- manifestations

      1.   CNS effects: confusion

      2.   Renal effects: oligouria, abnormally high serum creatinine and blood urea nitrogen (BUN)

      3.   Muscle effects: fatigue

      4.   Cardiac effects: angina

      5.   Gastrointestinal/CNS: anorexia

      6.  Skin/mucous membranes: cyanosis and poor capillary filling

    •  Hypotension (with exertion) is suggestive of reduced ventricular function due to ischemia.

  • ⁴Risk Indicators from Nuclear Stress Imaging

    • Defect number (irreversible and reversible)

    • Severity of hypoperfusion (mild to severe)

    • Eevated lung/heart  thallium uptake ratio

    • Left ventricular dilation induced by exercise.

    "Abnormal nuclear perfusion images of left ventricular myocardium  (Top right) During stress, under perfused areas appear less bright (arrows) because of diminished radio tracer uptake.   (Bottom right) At rest, myocardium appears perfused, indicating reversible ischemia" Zanger, D.R, Solomon, A.J., Gersh, BJ, Contemporary Management of Angina: Part I.  Risk Assessment American  Family Physician, December 1, 1999

  •  Dyspnea: at rest, with exertion, nocturnal, orthopnea, associated with angina

  •  Cardiac Function Tests:

    •  Identification of ventricular dyskinesia, akinesis, hypokinesis, aneurysms)

    •  Left ventricular end-diastolic pressures > 15 mm Hg

    •  Ejection fraction < 0.5

    •  Cardiac index < 2.5 liters/minute/meter²

    • ⁴High Risk Indicators associated with Treadmill Exercise Stress Test

      Exercise duration < 5 metabolic equivalents (1 metabolic equivalent = energy expended at rest)  ST-segment depression (see below)  Magnitude (>, = 2 mm)  Time of onset (stage I, II)  Duration (> 5 minutes)  ST segment depresssion observed in several ECG leads (>, = 5)    Blood Pressure  Low (< 130 mm Hg) peak systolic blood pressure  Decrease of systolic pressure to below initial resting standing blood pressure  Inability to attain target heart rate (target heart rate equals 85% of maximum predicted heart rate based on age (maximum predicted heart rate equals 220 - patients age)  Exercise-induced Angina  Ventricular ectopy (tachycardia/couplets) at low myocardial workload

  • Electrocardiogram:

    • Arrhythmia-associated hemodynamic changes

    •  Indications of ischemia/infarction

    • ST segmental depression

      • Acute:

        • may be associated with ischemia, non-Q wave infarction; hyperventilation, osmolality/electrolyte anomalies and drugs

        • ECG: obtain in patients with chest pain of unknown/uncertain etiology sense acute ST segmental shift may confirm ischemia (the amount of ST depression is measured from the PR segment (isoelectric line))

      • Chronic:

        • Non-specific cardiac disease marker -- associated with poor outcome

        • Causes: electrolyte abnormalities; drugs (e.g. digoxin (Lanoxin, Lanoxicaps)/digitoxin (Crystodigin))

        • Anatomical  correlation: subendocardial damage (note that Q waves may be more likely associate with transmural infarction damage)

    •  

      ST Segment Depression

      "ST segment depression is a nonspecific abnormality that must be evaluated in the clinical context in which it occurs.  In a patient with angina pectoris ST depression usually means subendocardial ischemia and, unlike ST elevation, is not localizing to a particular coronary artery lesion."-Frank G.Yanowitz, M.D. Dourtesy of: Frank G.Yanowitz, M.D. and  The Alan E. Lindsey  ECG Learning Center, used with permssion.

       

    • ST-segmental changes associated with myocardial ischemia, leads V4, V5, V6

  Shaded areas indicate ECG changes associated was myocardial ischemia (possibly exercise into his, in this case associate with angina), adapted from the NIH publication No. 92-2890, U.S. Department of Health and Human Services, Public Health Service, National Institutes of Health, National Heart, long,and Blood Institute, April, 1994.

  • Cardiac Catherization: Information Concerning Patient's Cardiovascular Status

    • "Right Heart Catherization:Information"

      •  Cardiac pressures

      •  0₂ saturations

      •  Cardiac output-thermal dilution or Fick principle  

      •  Systemic/pulmonary vascular resistance

      •  Introcardiac shunt (congenital heart disorders)

      •  Left atrial pressure estimate: derived from pulmonary capillary wedge pressure (PCWP)

    • "Left-heart Catherization -- angiographic information: 

      •  Method 1-- radioopaque contrast injected from a position above the aortic valve into the right and left coronary arteries which provides information concerning:

        •  Location and degree of stenosis/stenoses

      • Method 2--radioopaque contrast injection from a catheter advanced past aortic valve and into the left ventricle: results in "left  ventriculogram" which provides information concerning:

        •  Ejection fraction

        •  Ventricular wall motion anomalies

    •  3D CT-based reconstructions of coronary arteries-courtesy GE Medical Systems

      • Left ventricular end diastolic pressure (LVEDP) may be measured both before and after contrast  injection

        •  significant LVEDP increased after injection is indicative of  severe disease, since the contrast itself diminished function secondary to transient reduction in oxygen availability or by direct volume effects

   

  • Ventricular Functional Evaluation

    • Left ventricular end diastolic pressure (LVEDP) may be measured both before and after contrast  injection

      • • Left Image: diastole, A 6 French catheter is see in in the left ventricle (image was obtained at the end of diastole with maximal ventricular size and relaxation)

        • Right Image: systole-- minimal left ventricular size following ejection

        • Attribution:  Cardiovascular Research Institute of Southern California, Ronald P. Karlsberg, M.D., Clinical and Interventional Cardiology, Associate Clinical Professor of Medicine, UCLA School of Medicine, used with permission

    •  Significant LVEDP increased after injection is indicative of  severe disease, since the contrast itself diminished function secondary to transient reduction in oxygen availability or by direct volume effects.

   

  • Good Ventricular Function	Poor Ventricular Function
    Low filling pressures  (low: right atrial pressures, pulmonary artery pressures, wedge pressures, LVEDP) Normal cardiac output Satisfactory/high blood pressure	Elevated filling pressures Low cardiac output  Low blood pressure Assessment of "vascular resistance:limited value

     

  •  Ventricular dysfunction may be indicated by some ventricular function measures but not others.  

    •   In this case focus should be placed on the unfavorable hemodynamic parameter come e.g. LVEDP of 20 mm Hg may suggest ventricular abnormality despite a normal cardiac output

  • ⁵Ejection fraction-good indicator of myocardial function and surgical outcome (population: patients undergoing coronary artery bypass grafting procedures)

    • Ejection fraction > 0.4: best outcome i.e. Lowest mortality, morbidity, cost

    • Ejection fraction < 0.3: worse outcome

    • Ejection fraction between 0.3 and 0.39: intermediate outcome

  •  Low ejection fraction, < 0.4 = significant ventricular dysfunction

  • Ventricular dyskinesias: = significant ventricular dysfunction

    • Anterior wall myocardial dyskinesis/akinesis: more serious than similar findings associated with the inferior wall 

    • Cardiac output may be normal even with low ejection fraction and dyskinetic regions  in the presence of left ventricular aneurysm (ejection fraction is low due to systolic aneurysm region enlargement, but with sufficient remaining healthy myocardium, a normal cardiac output may be measured)

    • Diastolic phase superimposed on the systolic phase for ejection fraction calculation (percentage of blood volume that leaves the heart/beat); Cardiac regions with previous injury, i.e. scar tissue, are associated with impaired contractility (hypokinesis).  In the example above, the anterior apical region exhibits reduced motion secondary to previous left anterior descending vessel occlusion. Courtesy of: Cardiovascular Research Institute of Southern California, Ronald P. Karlsberg, M.D., Clinical and Interventional Cardiology, Associate Clinical Professor of Medicine, UCLA School of Medicine, used with permission.

       

  • Primary Reference:  Ross, AF, Gomez, MN. and Tinker, JH Anesthesia for Adult Cardiac Procedures in  Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., pp. 1659-1698, 1998.

  • Primary Reference: Shanewise, JS and Hug, Jr., CC, Anesthesia for Adult Cardiac Surgery, in Anesthesia, 5th edition,vol 2, (Miller, R.D, editor; consulting editors, Cucchiara, RF, Miller, Jr.,ED, Reves, JG, Roizen, MF and Savarese, JJ) Churchill Livingston, a Division of Harcourt Brace and Company, Philadelphia, pp. 1753-1799, 2000.

  • Primary Reference: Wray Roth, DL, Rothstein, P and Thomas, SJ Anesthesia for Cardiac Surgery, in Clinical Anesthesia, third edition  (Barash, PG, Cullen, BF, Stoelting, R.K, eds), Lippincott-Raven Publishers, Philadelphia, pp. 835-865, 1997

  • ⁴Zanger, D.R, Solomon, A.J., Gersh, BJ, Contemporary Management of Angina: Part I.  Risk Assessment American  Family Physician, December 1, 1999

  • ⁵Kay, GL, Sun, GW, Aoki, A, et al: Influence of ejection fraction on hospital mortality, morbidity, and costs for CABG patients, Ann. Thorac Surg 60 (6): 1640-1650, 1995 (2nd sourced from  Ross, AF, Gomez, MN. and Tinker, JH Anesthesia for Adult Cardiac Procedures in  Principles and Practice of Anesthesiology (Longnecker, D.E., Tinker, J.H. Morgan, Jr., G. E., eds)  Mosby, St. Louis, Mo., pp. 201-218, 1998)