Cardiac Physiology Flashcards
What happens at birth with cardiac output and myocardial contraction?
Increased
What is secreted at birth and increases rapidly?
Epinephrine and Norepinephrine
During transition, what happens to PVR?
Decreases, by 80%
During transition, what happens to systemic pressure?
Increases
What happens to pulmonary blood flow during transition?
Increases
What are the major pulmonary vasodilators active in transition?
Nitric Oxide and Prostacyclin
What do the vasodilators help with?
Adequate blood flow to the lungs
What is NO responsible for?
After birth, pulmonary vasodilation, bronchodilation, increased surfactant function, decreased lung inflammation
When is the ductus venosus closed?
Within minutes of birth with cessation of placental blood flow
What closes the FO?
Pressure changes in heart, increased systemic pressure, decreased pulmonary pressure
When does the FO close?
By 9 months, structurally by 1 year
What closes the DA?
Increased SVR and decreased PVR
What happens to blood flow of the DA after birth?
Shunt becomes left to right
When does functional closure of the DA happen?
12-14 hours of life
What is preload?
R/T length of muscle cells stretching
What is the Frank Starling Law?
Ability of heart to change its force of the contraction and therefore change stroke volume in response to change in venous return
What is Afterload?
The pressure the heart chamber must pump against to eject blood, As afterload increased cardiac output decreases
How are neonates affected by afterload?
Increased afterload and decreased contractility R/T PVR and SVR (more blood to eject blood)
How do neonates increase CO?
Increased HR
What are the central mechanisms of cardiac function regulation?
Medulla, Hypothalamus, and Cerebral Cortex
What is the result of sympathetic control of the heart?
Increased CO to 100%, Increased responsiveness with Gestational Age, Tachycardia, increased B/P, increased myocardial contractility
What is the result of parasympathetic control of the heart?
Decreased HR, Variability of fetal HR, Stimulates Vagus nerve to decrease HR
What does the adrenal medulla secrete to help with fetal cardiac function?
Catecholamines
What does the pituitary gland secreted to help with fetal cardiac function?
Vasopressin
