Chapter 25 Assessment of Cardiovascular Function

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

Anatomy of the Heart Figure 25-1

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

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

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

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

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

Cardiac Action Potential Cycle Figure 25-4

Greater Vessels, Heart Chambers and Pressures Figure 25-2

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

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

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

Contractility Contractility increased by catecholamines, SNS, some medications Decreased by hypoxemia, acidosis, some medications

Which of the following best defines stroke volume? 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

The amount of blood ejected with each heartbeat 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.

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

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

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

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

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

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

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?

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?

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

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

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

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

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

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

Hemodynamic Monitoring CVP Pulmonary artery pressure Intra-arterial BP monitoring

Phlebostatic Level Figure 25-10

Pulmonary Artery Catheter and Pressure Monitoring System Figure 25-12