Chapter 25 Assessment of Cardiovascular Function

1. Chapter 25Assessment of Cardiovascular Function

2. Overview of Anatomy and Physiology • Three layers: endocardium, myocardium, epicardium • Four chambers: Right atrium and ventricle, left atrium and ventricle • Atrioventricular valves: tricuspid and mitral • Semilunar valves: aortic and pulmonic • Coronary arteries • Cardiac conduction system (electrophysiology) • Cardiac hemodynamics

3. Anatomy of the Heart Figure 25-1

4. Cardiac Conduction System: Electrophysiology (60-100) (40-60) (30-40) (30-40) Figure 25-3

5. Question Which of the following is the primary pacemaker for the myocardium? • Atrioventricular junction • Bundle of His • Purkinje fibers • Sinoatrial node

6. Answer • Sinoatrial node Rationale: The sinoatrial node is the primary pacemaker for the myocardium.

7. Cardiac Action Potential • Depolarization: electrical activation of cell caused by influx of sodium into cell while potassium exits cell • Repolarization: return of cell to resting state caused by reentry of potassium into cell while sodium exits

8. Cardiac Action Potential (cont’d) • Refractory periods • Effective refractory period: phase in which cells are incapable of depolarizing • Relative refractory period: phase in which cells require stronger-than-normal stimulus to depolarize

9. Cardiac Action Potential Cycle Figure 25-4

10. Greater Vessels, Heart Chambers and Pressures Figure 25-2

11. Cardiac Hemodynamics • Stroke volume(SV): amount of blood ejected with each heartbeat • Preload: degree of stretch of cardiac muscle fibers at end of diastole • Afterload: resistance to ejection of blood from ventricle • Contractility: ability of cardiac muscle to shorten in response to electrical impulse

12. Cardiac Hemodynamics (cont’d) • Ejection fraction: percent of end diastolic volume ejected with each heart beat (left ventricle) • Cardiac utput (CO): amount of blood pumped by ventricle in liters per minute. • CO = SV × HR

13. Influencing Factors • Control of heart rate • Autonomic nervous system, baroreceptors • Control of stroke volume • Preload: Frank-Starling Law • Afterload: affected by systemic vascular resistance, pulmonary vascular resistance

14. Contractility • Contractility increased by catecholamines, SNS, some medications • Decreased by hypoxemia, acidosis, some medications

15. Question Which of the following best defines stroke volume? • The amount of blood ejected with each heartbeat • Amount of blood pumped by the ventricle in liters per minute • Degree of stretch of the cardiac muscle fibers at the end of diastole • Ability of the cardiac muscle to shorten in response to an electrical impulse

16. Answer • The amount of blood ejected with each heartbeat Rationale: Stroke volume is the amount of blood ejected with each heartbeat. Cardiac output is the amount of blood pumped by the ventricle in liters per minute. Preload is the degree of stretch of the cardiac muscle fibers at the end of diastole. Contractility is the ability of the cardiac muscle to shorten in response to an electrical impulse.

17. Health History • Demographic information • Family/genetic history • Cultural/social factors • Risk factors • Modifiable • Nonmodifiable

18. Most Common Clinical Manifestations • Chest pain • Dyspnea • Peripheral edema, weight gain • Fatigue • Dizziness, syncope, changes in level of consciousness

19. Question Where does the nurse auscultate the apex of the heart? • Erb’s point • Fifth intercostal space • Pulmonic area • Tricuspid area

20. Answer • Fifth intercostal space Rationale: The nurse auscultates the apex of the heart at the left fifth intercostal space at the midclavicular line.

21. Assessment • Physical examination • Palpation, percussion, auscultation • Medications • Nutrition • Elimination • Activity, exercise • Sleep, rest

22. Assessment (cont’d) • Vital signs • Self-perception, self-concept • Roles, relationships • Sexuality, reproduction • Coping, stress tolerance • Prevention strategies • Family history

23. Health Promotion, Perception, and Management Questions • Ask regarding health promotion, preventive practices • What type of health issues do you have? Are you able to identify any family history or behaviors that put you at risk of this health problem? • What are your risk factors for heart disease? What do you do to stay healthy? • How is your health? Have you noticed any changes?

24. Health Promotion, Perception, and Management Questions (cont’d) • Ask regarding health promotion, preventive practices • Do you have a cardiologist or primary health care provider? How often do you go for checkups? • Do you use tobacco or alcohol? • What medications do you take?

25. Laboratory Tests • Cardiac biomarkers • CK, CK-MB • Myoglobin • Troponin T and I • Lipid profile • Brain (B-type) natriuretic peptide • C-reactive protein • Homocysteine • Refer to Table 25-4

26. Electrocardiography • 12-lead ECG • Continuous monitoring: hardwire, telemetry • Signal-averaged ECG • Continuous ambulatory monitoring • Transtelephonic monitoring • Wireless mobile monitoring

27. Electrocardiography (cont’d) • Cardiac stress testing • Exercise stress testing • Pharmacologic stress testing • Echocardiography • Transthoracic • Transesophageal

28. Diagnostic Tests • Radionuclide imaging • Myocardial perfusion imaging • Test of ventricular function, wall motion • Computed tomography • Positron emission tomography • Magnetic resonance angiography

29. Cardiac Catherization • Invasive procedure study used to measure cardiac chamber pressures, assess patency of coronary arteries • Requires ECG, hemodynamic monitoring; emergency equipment must be available • Assessment prior to test; allergies, blood work

30. Cardiac Catherization (cont’d) • Assessment of patient postprocedure; circulation, potential for bleeding, potential for dysrhythmias • Activity restrictions • Patient education pre- and postprocedure

31. Hemodynamic Monitoring • CVP • Pulmonary artery pressure • Intra-arterial BP monitoring

32. Phlebostatic Level Figure 25-10

33. Pulmonary Artery Catheter and Pressure Monitoring System Figure 25-12