Perfusion Flashcards
Perfusion
Flow of blood through arteries and capillaries, delivering nutrients and oxygen to cells and removing cellular waste products
Cardiovascular System Function
- Supply oxygenation to the body
- Perfusion affects all body functions and systems
Central Perfusion
- Force of blood movement generated by cardiac output
- Requires adequate cardiac function, blood pressure, and blood volume
- Requires adequate cardiac output
Tissue Perfusion (Local)
- Volume of blood that flows to target tissue
- Requires patent vessels, adequate hydrostatic pressure, and capillary permeability
Impaired Tissue Perfusion
Loss of vessel patency or permeability, or inadequate central perfusion
Localized Effect
Results in impaired blood flow to the affected body tissue
Leads to ischemia and, ultimately, cell death if uncorrected
Impaired Tissue Perfusion Symptoms
- Hypotension
- Restlessness
- Confusion
- Cool Extremeties
- Pallor or cyanosis
- Diminished or absent peripheral pulses
- Slow capillary refill
- Edema
- Oliguria
Impaired Central Perfusion
Occurs when cardiac output is inadequate.
Associated with loss of vessel patency of permeability.
Systemic Effect
Reduced cardiac output results in a reduction of oxygenated blood reaching the body tissues
If severe, associated with shock
If untreated, leads to ischemia, cell injury, and cell death
Pericardium
Thin sac composed of fibroserous material that surrounds the heart
- outer layer
- inner layer
- fluid between layers
Layers of the heart muscle
- Epicardium
- Myocardium
- Endocardium
Valves
Permit the flow of blood between chambers and into blood vessels
Each valve has 3 leaflets (cusps) except the mitral which has 2
Atrioventricular (AV) valve
- Tricuspid
- Mitral
- Made of endocardium and connective tissue
- Between atria and ventricles
Semilunar (shaped like half moons) valves
- Pulmonary
- Aortic
- Made of endocardium and connective tissue which are reinforced by fibers that prevent them from turning inside out
Vasoconstriction
Causes cell death
Ex) hypothermia
Heart Tissue Pattern
Pericardium >serous pericardium (parietal) >space >serous pericardium (visceral) >myocardium >endocardium
3 places blood goes:
- Carotid to brain
- Axillary arteries to arms
- Torso to toes
Ischemia
Lack of oxygen to tissues
Compliance
Elasticity of lungs
Contractility
Heart muscle fibers elasticity
Chordae Tendinae
Tricuspid valve and mitral valve made up of connective tissue
Conduction system of the heart
Sinoatrial node (SA) > Intra atrial pathways> AV node> Bundle of His> Right/Left bundle branches> Purkinje fibers
Contraction
Systole reaction
“Lub” AV valves closing
Relaxation
Diastole
“Dub” SemiLunar valves closing
Pulmonary Circulation
Circulates blood to lungs
-Low pressure system
Systemic circulation
Blood circulates to body
-high pressure system
Coronary Circulation
Blood flows to the heart
Heart Rate
Affected by the autonomic heart system
Sympathetic Nervous System
Increases heart rate
Parasympathetic Nervous System
Slows heart rate
Elevated heart rate
Increases Cardiac Output
Rapid HR decreases filling time which decreases output
Decreased Heart Rate
Decreased Cardiac Output
Stroke Volume
The amount of blood pumped by the left ventricle of the heart in one contraction
(End Diastolic Volume) - (End Systolic Volume) = SV
Diastole Phase
Ventricles fill by gravity and then by atrial systole. This blood is considered end diastolic volume.
Systole Phase
Blood is pumped from the ventricle. Some blood is left over called end systolic volume
Ejection Fraction
Stroke Volume / end systolic volume
Represents % of blood ejected from the heart during contraction
Normal is 50-70%
Damaged hearts have reduced EF and decreased perfusion to body systems
Cardiac Output
SV x HR
Amount of blood pumped into pulmonary and systemic circulation in 1min.
Avg. adult CO is 4-8L/min
Poor tissue perfusion=tissue ischemia=tissue necrosis or infarction (death)
CO decreases with poor heart
Factors determining CO
HR
Preload
Afterload
Contractility
Contractility
Ability of heart muscle fibers to shorten
Poor contractility decreases forward flow of blood=decrease CO, increase ventricular pressures
Preload
Stretch of cardiac muscle fibers
- initial stretching of the cardiac myocytes prior to contraction
Starling’s Law
- The greater the volume, the greater the stretch, the greater the force of contraction to empty
- Too much volume causes overstretch, ineffective contraction, causes HF, renal disease
- Too little volume, too little stretch, decreases CO (fluid volume deficit)
After load
- Force of ventricles must overcome to eject blood
- end load against which the heart contracts to eject blood
Pulmonary Vascular Resistance
Low pressure (right heart)
Systemic Vascular Resistance
High pressure (left heart)
CV changes with aging
- Myocardial hypertrophy
- Stiffened heart valves (fibrosis & calcification)
- Stenosis or incompetence of valves
Perfusion affects:
Renal system Vascular system Look at cholesterol Serum lipids (circulated blood bound to proteins) Triglycerides Phospholipids Troponin I (0.5-2.3mg/ml)
MI Indicators
Troponin greater than 2.3ng/ml
Echoes needed for heart issues
ST segment on tele
