Disorders of Cardiac Function Flashcards
What is the Pericardium?
3-layer sac surrounding heart.
What is the Myocardium?
middle layer of striated muscle made of sarcomeres.
What is the Endocardium?
innermost heart lining.
How does the myocardium work?
Cells contain many large mitochondria for energy to pump continuously.
Forms atria and ventricles.
Cardiac muscles require calcium for contraction.
How does the endocardium function?
Outer layer of the endocardium contains blood vessels and some nerve fibers of the cardiac conduction system.
What do the valves of the heart do?
Valves promote antegrade (forward direction) blood flow.
Separate atria and ventricle chambers.
What are the two valves?
Semilunar valves
Atrioventricular valves
What are the components of
Atrioventricular valves/ what do they do?
Mitral valve (bicuspid) and tricuspid valve
Prevent retrograde (backward direction) blood flow from ventricle into atria
What are the components of
Semilunar valves/ what do they do?
Pulmonic and aortic valves
Prevent retrograde (backward direction) blood flow into ventricles
What is preload?
Ventricular filling is the amount of blood the heart must pump with each beat.
Determined by venous return to heart and accompanying stretch of cardiac muscle fibers.
What is afterload?
Resistance to ejection of blood from heart.
Narrowed arteries or stenotic heart valve increases afterload.
Arterial blood pressure is the main source of afterload on left side heart
Pulmonary arterial pressure main source of afterload in right side heart
What is cardiac contractility?
Ability of heart to change force of contraction without changing resting length (diastole).
What is heart rate?
Frequency when blood is ejected from heart usually specified as beats per minute.
What is the importance of cardiac output? What is the equation for cardiac output?
The heart continuously attempts to maintain adequate cardiac output to provide oxygen and nutrients for all cells.
Cardiac output = heart rate × stroke volume
What is stroke volume? What is the equation of stroke volume?
Stroke volume is the amount of blood ejected with one heart beat.
Stroke volume = cardiac output / heart rate
What does stroke volume include?
Stroke volume includes preload, afterload, and cardiac contractility
What is the Frank-Starling Mechanism or Starling Law of the Heart?
Increased force of contraction that accompanies an increase in the volume of blood in the ventricles.
Tension and force of contraction is related to the degree the muscle fibers are stretched just before ventricles begin to contract.
What is the Frank-Starling Mechanism?
An increase in resting muscle fiber length will produce a more forceful cardiac contraction
What is the tipping point in the Frank-Starling Mechanism? What can it result in?
The heart muscle (myocardium) loses elasticity as it works harder and harder to try to maintain adequate cardiac output.
The result is heart failure.
What object can be related to the Frank-Starling Mechanism?
A rubber band when a pulling action is inhibited.
What is the Right Coronary Artery?
Supplies the right atrium, right ventricle, and part of the wall of left ventricle
What is the Left Coronary Artery (2 branches)?
Left Anterior Descending (LAD)
Left Circumflex Artery (LCA)
What’s a question we’d need to know about the heart?
Is the myocardium (muscle layer) of the heart receiving adequate blood supply?
What are some questions we need to know about the individual?
Is the heart size normal?
Is the heart contracting normally?
Is cardiac output adequate to supply blood throughout the body?
What can occur in the individual with inadequate blood supply to the myocardium?
What does the nurse assess for as indicators of adequate cardiac output?
What assessment findings can occur with decreased cardiac output?
What influences myocardial oxygen supply? (There is 5)
Blood flow through coronary arteries and capillaries to the myocardium
Oxygen intake through the respiratory tract
Red blood cell count
Oxygen content of hemoglobin
Hemoglobin ability to release oxygen
Low level of which electrolyte decreases hemoglobin release of oxygen ?
Phosphorus
What is Myocardial Oxygenation?
Identify conditions that can cause decreased myocardial oxygen supply (MVO2)
Identify factors that can cause increased myocardial oxygen demand
What happens when oxygen demand exceeds oxygen supply?
Myocardial ischemia with possible progression to infarction
Lactic acid accumulation
CHEST PAIN
What is Chronic Ischemic Heart Disease?
Arteriosclerosis
Atherosclerosis
- Early lesions
- Gradually progressive lesions
Angina pectoris
- Stable
- Variant – also called vasospastic or Prinzmetal’s
What are the clinical manifestations of Acute Coronary Syndromes?
Arteriosclerosis
Atherosclerosis
- Advanced lesions
Unstable angina
Acute myocardial infarction
What is the etiology of Chronic Ischemic Heart Disease?
Decreased myocardial perfusion
Coronary artery obstruction / thrombosis / occlusion
Coronary artery spasm
What is Angina Pectoris?
Pain of the chest
What is Stable angina?
Chest pain due to increased myocardial oxygen demand such as physical activity, cold, and/or emotional stress. Responds to medication and rest.
What is Variant angina (also called vasospastic or Prinzmetal’s)?
Chest pain due to coronary artery spasm with absent or minor coronary artery atherosclerosis.
What is the definition of Acute Coronary Syndrome?
Coronary artery atherosclerosis has worsened gradually, but a sudden thrombus has occurred in a coronary artery or arteries.
What are the clinical manifestations of Unstable Angina?
Sudden onset
- Pain – chest, jaws, teeth, arms, back shoulders
- Nausea/vomiting
- Diaphoresis
Less predictable than stable angina.
Greater instability of blood flow than stable angina.
May not respond to usual rest or medications.
This might be resolved with proper treatment and/or could become an acute myocardial infarction.
What is the etiology of myocardial infarction?
Death of myocardial cells due to prolonged imbalance between myocardial oxygen supply and demand.
Often begins with subendocardial layer and moves outward through layers of heart wall.
Sometimes not all layers of the heart are affected by the infarction.
Myocardial infarction: Rapid formation of _____________within coronary artery (ies).
Thrombus
Myocardial infarction: Cellular damage proceeds _________________ (through the wall, from inside to outside).
Transmurally
What is the pathophysiology of myocardial infarction?
Death of myocardial cells with eventual formation of non-functional scar tissue.
Electrical impulse cannot travel through connective scar tissue so this leads to abnormal cardiac rhythms.
Electrical activity and contraction are permanently impaired
What are some clinical manifestations of myocardial infarction?
Signs/symptoms are related to inadequate blood perfusion (i.e. oxygen and nutrients) to various organs/tissues
Severe chest pain unrelieved by rest and/or up to 3 nitroglycerin tablets
- Pain spreads to arms, neck, jaws, head, mid-back
- Sternal pressure
- Fever
- Nausea/vomiting
- Diaphoresis
- Decreased blood pressure
- Increased or decreased heart rate
What clinical findings would the nurse expect in the client with acute myocardial infarction related to inflammation?
Increased heart rate
Increased respiratory rate
Blood pressure is variable
Fever
What are some exceptions to classic clinical manifestations of acute MI?
“Silent” myocardial infarction – No chest pain
- Occurs in conditions that have decreased nerve sensation - neuropathy
- Diabetes mellitus
- Chronic neurological diseases
What does MI look like in females?
Symptoms can be non-specific and differ from typical manifestations
Unusual and/or persistent GI symptoms
Pain in back/shoulders
May not have chest pain OR could have chest pain
What are the components of Valvular Heart Disease?
Stenosis
Incompetent or regurgitant
What is Stenosis?
Inadequate opening
Obstruction of blood flow
What is Incompetent or Regurgitant?
Inadequate closing
Allows backward blood flow into preceding chamber
Valvular Heart Disease: Congenital
15-20% US population
Valvular Heart Disease: Acquired
Rheumatic fever
MI
Trauma
Drug interactions
IV drug abuse
What is the pathophysiology of Valvular Heart Disease?
Alteration of blood flow due to valve dysfunction can lead to:
- Decreased filling of the ventricle (s)
- Decreased stroke volume
- Increased cardiac workload
DECREASED CARDIAC OUTPUT
What does the nurse assess for with the right sided valves?
Decreased cardiac output
Peripheral edema
Heart murmur
Jugular vein distention
Chest pain
What does the nurse assess for with left sided valves?
Decreased cardiac output
Pulmonary congestion
Heart murmur
Bounding peripheral pulse
Heart is working harder than usual
Chest pain
What are cardiac murmurs?
A murmur is a sound heard with the stethoscope due to turbulent blood flow through an anatomically abnormal cardiac valve.
How is Heart Failure an example of Inadequate Cardiac Output?
Increased myocardial workload leads to hypertrophy and remodeling of the size and shape of the heart – this is Heart Failure.
What is the etiology of heart failure?
Cardiac causes
- Coronary heart disease
- Acute myocardial infarction
- Cardiac trauma
- Congenital anomalies
Non-cardiac causes – Heart was healthy
- Fluid volume overload from any source
- Renal failure
- Aggressive fluid resuscitation
What are the risks factors of heart failure?
Advanced age
Any form of heart disease
Hypertension
Cardiac dysrhythmias
Anemia
High salt intake
High calorie intake
Obesity
Smoking
Polypharmacy
What tests is used to screen for heart failure?
Brain natriuretic peptide (BNP) lab test
Level of Prevention?
What does this lab test indicate about the heart?
Brain natriuretic peptide (BNP) lab test
Level of the BNP lab test increases due to stretch of the myocardium, especially the ventricles, as fluid volume or pressure increases within the ventricles.
It’s excess fluid inside the heart that makes it stretch more than normal.
what is the Heart failure pathophysiology?
Ineffective cardiac pumping
- Myocardial remodeling (changes in size and shape) often occurs prior to clinical symptoms.
- Cardiac electrical conduction irritability produces cardiac dysrhythmias.
- Increased pressure in cardiac chambers is due to increased blood volume in heart and lungs.
Neurohormonal compensatory responses
- Catecholamine increase - Norepinephrine stimulates vasoconstriction.
- Aldosterone-renin-angiotensin stimulation due to decreased cardiac output to kidneys.
- Kidney sodium and water reabsorption is increased.
Heart failure usually occurs FIRST in the heart’s left side, then progresses to the right side. Why?
When the left ventricle fails and can’t pump enough blood out, increased fluid pressure is transferred back through the lungs. This damages the heart’s right side. When the right side loses pumping power, blood backs up in the body’s veins.
When might right heart failure occur alone or before development of left heart failure?
When caused by COPD or heart valve disease
What is the etiology of left sided heart failure?
Chronic hypertension
Left ventricular dysfunction
Left ventricle infarction
What are the mechanisms of left sided heart failure?
Ineffective pumping of left ventricle
Blood backs up in left atrium and pulmonary blood vessels
Pulmonary edema
What are some clinical manifestations of left sided heart failure?
pulmonary congestion
Orthopnea
Exertional dyspnea
Cough
Blood-tinged sputum
What is pulmonary edema?
Sudden life-threatening heart failure occurs when pulmonary vessels can no longer hold the excess blood that is backed up.
What are some signs of pulmonary edema?
Severe pulmonary congestion.
Feeling of impending doom.
Frothing at the mouth.
Severe impaired gas exchange.
What is the etiology of right sided heart failure?
Right ventricle infarction
left-side heart failure
What are the mechanisms to right sided heart failure?
Ineffective pumping right ventricle
Blood backs up in right atrium & venous system
What are some clinical manifestations of right sided heart failure?
Jugular venous distention
Peripheral /dependent edema
Organ edema – Liver, spleen
Ascites
Intestinal malabsorption
Anorexia
What are the FACES of Heart Failure?
Fatigue
Activities limited
Chest congestion
Edema or ankle swelling
SOB
