Assessment Of The Cardiovascular System Flashcards
Overview of Anatomy and Physiology
- Three layers: endocardium, myocardium, epicardium
- Four chambers: Right atrium and ventricle, left atrium andventricle
- Atrioventricular valves (AV valves): tricuspid (right) and mitral (left)
- Semilunar valves: aortic and pulmonic
- Coronary arteries
- Cardiac conduction system (electrophysiology)
Anatomy of the Heart
- There’s a difference in thickness between atrium and ventricles because atrium doesn’t have to work as hard because blood flows down into ventricles
- Left ventricle is bigger because it has to push blood to body
- Right ventricle could be big because of increased pulmonary pressure
Pericardium
- Double-walled sac that encloses the heart. (Two layers)
- Serves as support and protection
- Pericardial fluid is found between the layers of the pericardium
- Minimizes friction of the layers as they rub together with each heartbeat
— A little fluid is fine but too much can be an issue
Heart Chambers
Right atrium
- Receives deoxygenated blood from the body; delivers blood to right ventricle
Right ventricle
- Pumps blood to the lungs for oxygen
Left atrium
- Receives oxygenated blood from the lungs, delivers blood to the left ventricle
Left ventricle
- Pumps blood out to the entire body
Heart Valves
- Open and close based on changes in pressure
- Open only in the direction of blood flow
- Closure is responsible for the sounds made by the beating heart.
- S1: closure of mitral and tricuspid valve (AV valves)
- S2: closure of the semi-lunar valves (aortic and pulmonic valves)
- Between S1 and S2 the heart is contracted sending blood to the body (systole)
- Between S2 and S1 the heart is at rest and filling with blood (diastole)
- During diastole the coronary arteries are being purfused because they couldn’t perfuse when its contracted
Semilunar valves
Pulmonic valve
- Located between right ventricle and pulmonary artery
Aortic valve
- Located between left ventricle and aorta
Atrioventricular (AV) valves
Tricuspid valve
- Located between right atrium and ventricle
- Has three cusps
Mitral valve
- Located between left atrium and ventricle
- Has two cusps
Coronary Arteries
- Perfused during diastole when coronary vascular resistance is minimized
- Mean arterial pressure (MAP): 60 minimum maintains perfusion of organs like the kidneys and the brain
- Need to Know:
— Right main coronary
— Left main coronary
— Left anterior descending (LAD) coronary artery
— Circumflex coronary artery
Heart Cells
Contractile cells
- Cause the heart to contract
Conduction system cells
- Create and conduct impulses to regulate the cardiac cycle
- Nodal cells and Purkinje cells
— Automaticity: ability to initiate an electrical impulse
— Excitability: ability to respond to and electrical impulse
— Conductivity: ability to transmit an electrical impulse from one cell to another
Cardiac Conduction System: Electrophysiology
Photo: the branch connecting to the Left Atrium: Bachmann’s bundle/ branch
Which of the following is the primary pacemaker for
the myocardium?
Sinoatrial node
What is known as the gatekeeper of the hearts electroconduction system?
The AV node
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
- 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
Refractory Periods
Absolute
- No stimulus can cause depolarization.
Relative
- Strong stimulus can cause depolarization.
Supernormal period
- Even a weak stimulus can cause depolarization.
- Cardiac cell is “hyper.”
4 stages of the cardiac cycle
- Refers to the events that occur in the heart from the beginning of one heartbeat to the next
- Number of cycles depends on heart rate
- Each cycle has three major sequential events:
— Diastole
— Atrial systole
— Ventricular systole
Mechanical Properties of the Heart: heart rate
- Heart rate- number of times the ventricles contract each minute
- Controlled by Autonomic Nervous System
— Sympathetic Nervous System
—- Fight or flight: speeds up HR; digestion slows
— Parasympathetic Nervous System
—-Vagus nerve slows the HR; increases digestion
Mechanical Properties of the Heart:
Cardiac output (CO)
- Amount of blood pumped from left ventricle per minute determined by Heart rate × Stroke volume.
- Tells what amount of blood flow goes into systemic circulation.
- Normal is 4-7 liters per minute
Mechanical Properties of the Heart:
Stroke Volume
- the amount of blood ejected by left ventricle during each contraction
- Average resting stroke volume is 60-130 mL with each contraction
Influencing Factors on Cardiac Output
- Control of heart rate
— Autonomic nervous system, baroreceptors - Control of stroke volume
— Preload: Frank–Starling Law: stroke volume of the heart increases in response to the volume of blood in the ventricles before contraction; due to the increased stretch
— Afterload: affected by systemic vascular resistance (SVR) (BP), pulmonary vascular resistance
—- Infection: vasodiated/ low BP
Mechanical Properties of the Heart:
Preload
- degree of myocardial fiber stretch at end of diastole just before contraction.
- determined by the amount of blood returning to the heart from both the venous system (right heart) and the pulmonary system (left heart)
Mechanical Properties of the Heart
Afterload
- pressure or resistance ventricles overcome to eject blood through semilunar valves and into peripheral blood vessels.
- resistance is directly related to arterial blood pressure and the diameter of the blood vessels.
Mechanical Properties of the Heart:
Myocardial contractility
- force of cardiac contraction independent of preload
- increased by sympathetic stimulation, calcium release, and positive inotropic drugs.
- decreased by hypoxia, acidosis, certain medications such as Beta –adrenergic blocking agents such as Metoprolol
- Normal pH: 7.35 - 7.45
- acidosis: <7.35
Assessment of the CV System
- Health history
- Common symptoms
- Chest pain/discomfort
- Pain/discomfort in other areas of the upper body
- SOB/dyspnea
- Peripheral edema, wt gain, abd distention
- Palpitations
- Unusual fatigue, dizziness, syncope, change in LOC
Past Health, Family, and Social History
- Medications
- Nutrition
- Elimination
- Activity, exercise
- Sleep, rest
- Self-perception/self-concept
- Roles and relationships
- Coping and stress
- Are your parents alive/ have they had any cardiac problem
Physical Assessment of CV System
- General appearance
- Skin and extremities
- Pulse pressure
- Blood pressure; orthostatic changes
- Arterial pulses
- Jugular venous pulsations
- Heart inspection, palpation, auscultation
- Assessment of other systems
Risk Factors Non-Modifiable: Can’t change
- Age
- Gender; males and post menopausal women
- Race
- Family history; gene mutations
Modifiable Risk Factors: Can change
- Hyperlipidemia: high cholesterol
- Smoking
- Hypertension
- Diabetes
- Physical Inactivity/Obesity
- Metabolic Syndrome: 3 or more of the above
The nurse understands that which assessment finding is the best indicator of fluid retention?
Weight gain
Cardiac Laboratory Tests
- Cardiac biomarkers
— CK-MB: CK isoenzymes
— *Troponin T & I proteins: marker for heart attack; faster to look at - Blood chemistry, hematology, coagulation
- Lipid profile
- Brain (B-type) natriuretic peptide: enzyme heart releases during heart failure
- C-reactive protein: inflammation
- Homocysteine
Electrocardiography
- 12-lead ECG
- Continuous monitoring
- Hardwire
- Telemetry
- Lead systems
- Ambulatory monitoring
Cardiac Stress Testing
Exercise stress test
- Pt walks on treadmill with intensity progressing according to protocols
- ECG, V/S, symptoms monitored
- Terminated when target HR is achieved
Pharmacologic stress testing
- Vasodilating agents given to mimic exercise
Heart Diagnostic Tests
Radionuclide imaging:
- Myocardial perfusion imaging
- Positron emission tomography (PET)
- Test of ventricular function, wall motion
- Computed tomography (CT)
- Magnetic resonance angiography (MRI)
Echocardiography
- Noninvasive ultrasound test that is used to:
- Measure the ejection fraction
- Examine the size, shape, and motion of cardiac structures
- Transthoracic
- Transesophageal: invasive; done with physician present
Cardiac Catheterization Most definitive, most invasive
- Involves use of contrast agent Invasive procedure used to diagnose structural and functional diseases of the heart and great vessels
Right Heart Cath - Pulmonary artery pressure and oxygen saturations may be obtained; biopsy of myocardial tissue may be obtained
Left Heart Cath - Involves use of contrast agent
- Ask about iodine allergy
Nursing Interventions-Cardiac Cath
- Observe arterial insertion site for bleeding, hematoma
- Assess peripheral pulses
- Evaluate temp, color, and cap refill of affected extremity
- Screen for dysrhythmias
- Maintain bed rest 2 to 6 hours
- Instruct patient to report chest pain, bleeding
- Monitor for contrast-induced nephropathy:
- Make sure the pt has good urine output post catheterization
- Ensure patient safety
