Lecture 15 - Cardiac Failure, Heart Sounds, and Circulartoy Shock Flashcards
What is cardiac failure?
Slide 5
-failure of the heart to pump enough blood to meet the needs of the body
What compensatory mechanism occur following acute cardiac failure?
(Slide 9)
ANS:
- baroreceptor reflex
- chemoreceptors reflex
- CNS ischemic response
Strong sympathetic stimulation:
- strengthens damages muscle
- normal muscle is strongly stimulated
- increase in venous tone -> decrease venous compliance -> increase venous return
What are the acute effects following an acute heart attack?
Slide 12
- reduced cardiac output
- damming of blood in veins resulting in increased venous pressure
What are the chronic compensations following an acute heart attack?
(Slide 12 and 25)
- pumping ability is depressed to less than half normal
- heart loses ability to compensate for increased activity
- increase in right atrial pressure
How does left heart failure cause pulmonary edema?
Slide 18
- blood is pumped into the lungs but not enough is pumped out
- mean pulmonary filling pressure increases
- pulmonary capillary pressure increases
- increase above colloid osmotic fluid pressure (28 mmHg) results in fluid filtering into interstitial spaces of the lungs and alveoli
What are the two major problems of left heart failure?
Slide 19
- pulmonary vascular congestion
- pulmonary edema
What is the difference between a compensated and decompensated heart?
Compensated:
- right atrial pressure increases
- cardiac output eventually returns to normal (5L/min)
Decompensated:
-right atrial pressure progressively increases but cardiac output never reaches level needed to maintain normal fluid balance
What conditions can lead to high output cardiac failure? What effect does it have on the venous return curve?
(Slide 34)
Arteriovenous fistula:
- overloads heart due to increased venous return
- rotates venous return curve upward
Beriberi:
- weakening of the heart due to thiamin deficiency
- decreased blood flow to the kidneys resulting in fluid retention
- shift venous return curve to the right
What events correspond with the first and second heart sound?
(Slide 38)
First heart sound:
-AV valve closing at onset of systole
Second heart sound:
-semilunar valve closing at end of systole
Differentiate between left-to-right and right-to-left congenital defects.
(Slide 41)
Left-to-right:
- some blood flows backwards through the heart and not into systemic circulation
- patent ductus arteriosus
Right-to-left:
- blood flows from right to left side of heart bypassing the lungs
- tetralogy of Fallot
What is circulatory shock?
Slide 44
-inadequate blood flow through the body causing tissues to be damaged from lack of oxygen or other nutrients
What are the main factors that reduce cardiac output?
Slide 46
Decrease in the ability to pump blood
Decrease in venous return
Describe the negative feedback system that return cardiac output and arterial pressure to normal following cardiac shock.
(Slide 49)
-arterial baroreceptors stimulate powerful sympathetic response
-sympathetic response causes:
—arterioles to constrict in most parts of systemic circulation
—veins and venous reservoirs constrict
—heart rate increases markedly
-autoregulation In cerebral and cardiac vessels maintains relatively normal pressure if atrial pressure remains above 70mmHg
What role do renin, epinephrine, and vasopressin/ADH have on recovery from shock?
(Slide 50-51)
Renin:
-causes production of angiotensin II which constricts arterioles and decreases output of water and salt by kidneys
Epinephrine:
- consticts peripheral arteries and veins
- increases heart rate
Vasopressin/ADH:
- constricts peripheral arteries and veins
- greatly increases water retention of kidneys
What differentiates non-progressive and progressive shock?
Slide 54
Non-progressive shock:
- sympathetic reflex’s compensate enough to prevent deterioration
- negative feedback
Progressive shock:
- reflex’s are not able to sufficiently compensate causing myocardium to not receive adequate nutrients and weaken
- positive feedback
