Exam 2 – Cardio Ch 23 Flashcards
What is the placenta responsible for?
Nutrient and oxygen delivery to the fetal blood
When does the heart start beating?
At 18 days
In the fetus, what side of the heart has a higher pressure?
The right side, or the two sides could be somewhat equal
What does blood to the fetus come through?
Umbilical vessels
What are the different fetal accommodations?
Umbilical vessels, urachus
PDA, foramen ovale
Fetal hemoglobin
What is the placenta the site of?
Oxygenation
What is the ductus venosus?
Bypassing the liver (nonfunctional)–from umbilical vein to inferior vena cava directly
What is the foramen ovale?
Shunt from right to left atrium
Oval hole
Highest O2 content to left ventricle to supply carotid and brain
What is the ductus arteriosus?
Shunt from pulmonary artery to aorta, also right to left shunt
Look at the organization of the fetal circulation
Look at the organization of the fetal circulation
Where do umbilical arteries come off?
Close to where the renal arteries come off
What do umbilical arteries do?
Pick up nutrients and oxygen then goes to the umbilical vein
What does the umbilical vein carry?
Oxygenated blood
Where does the highest oxygenated blood go through?
Right atrium
What does 30% of the blood go out of?
Pulmonary artery
What does most of the blood bypass?
The lungs
What is a very common infection in calves?
Umbilicus infections
Where do the 2 umbilical arteries go?
Go through the bladder and join the umbilical vein
What happens to blood due to the fact that capillaries have a higher pressure?
Blood is forced into the aorta
Which has a higher affinity for oxygen, fetal Hgb or mother Hgb?
Fetal Hgb
What does loss of blood flow from the placenta cause?
2X increase in vascular resistance
Decreased venous return to right atrium
Increased aortic pressure
When does the ductus venosus close?
3-7 days after birth
What does the closing of the ductus venosus cause?
Loss of umbilical venous return and low blood flow
What causes pulmonary vascular resistance to decrease?
Lung expansion
Lung vasculature vasodilates
After birth, which side of the heart is the high pressure system? Low pressure system?
Left side
Right side
What changes at birth?
Loss of placenta
First breath decreases vascular resistance in lung
Closure of foramen ovale
Closure of ductus arteriosus
What is the closure of the ductus arteriosus related to?
Oxygen content
How long does it take for the ductus arteriosus to fully close?
1-8 days
Which has lower O2, fetus or adults?
Fetus
What is the most common feature for horses to have?
A ductus arteriosus that does not fully close, cuasing there to be a sound similar to a murmur
Describe the 1st heart sound
Lub
AV valves close
Luder than the second sound
Low pitch
Describe the second heart sound
Dup
Aortic and pulmonary valves close
Describe the 3rd heart sound
Very low pitch
Caused by inrushing of blood into ventricles
Describe the 4th heart sound
Atrial contraction late in diastole
Hard to hear with stethoscope except in hypertensive patients with a thick left ventricle
What are cardiac sounds?
Vibrations
What causes more vibrations (cardiac sounds)?
Turbulent flow
What happens if there is a larger vessel and larger turbulence?
The sound is louder
What happens if the opening is smaller?
The turbulence is greater
What are acquired heart defects?
Stenosis
Insufficiency
What are congenital heart defects?
Atrial septal defect
Ventricular septal defect
Tetralogy of fallot
Which side will you always be able to hear the heart better?
Left
What do we listen to on the left side of the heart?
Pulmonic, aortic, and mitral valves
What do we listen to the right side of the heart?
Tricuspid valves
What is the grading of heart murmurs based on?
Timing Loudness Point of maximal intensity Cardiac thrill Acquired vs congenital
What are the different timings of murmurs?
Systolic/pansystolic or holosystolic
Diastolic/pandiastolic of holodiastolic
Continuous (systole and diastole)
Crescendo-decrescendo
How is the loudness of murmurs evaluated?
Grade I-VI/VI
What is the modulation for systolic murmurs?
Crescendo-decrescendo
What are the association with a systolic murmur?
Congenital pulmonic stenosis Congenital aortic stenosis Innocent murmurs Mitral regurgitation Tricuspid regurgitation Ventricular septal defect
What is the modulation of diastolic murmurs?
Decrescendo
What are the associations with diastolic murmurs?
Aortic regurgitation
Aortic valve bacterial endocarditis
Secondary to chronic aortic stenosis
Secondary to a high ventricular septal defect
What is the modulation of continuous murmurs?
Machinery
What are the associations with diastolic murmurs?
Patent ductus arteriosis
Tetraology of fallot
What is stenosis?
Narrowing/scarring–systolic
What is insufficiency?
Not sealing, leaky–diastolic
Regurgitation
What are the valves most commonly affected by a murmur?
Mitral valves (most common in dogs) Tricuspid valves (most common in cattle, horses, and pigs) Aortic valve (second most common in dogs)
What are results of heart valve damage?
Stenosis
Destruction of valve –regurgitation or insufficiency
Describe mitral stenosis
Murmur heard in last 3rd of diastole
Thrill over apex of heart
Low rumbling murmur
What are the hemodynamics of mitral stenosis?
Cardiac output and mean arterial pressure do not decrease nearly as much as in aortic stenosis
Atrial volume leads to atrial fibrillation
Right ventricle pressure could lead to right ventricle failure
Left atrial pressure could cause pulmonary edema
Left ventricle is normal
What is mitral regurgitation?
Idiopathic myxomatous degeneration
Blowing murmur head throughout systole–high pitch
Best heard over left thorax
When does regurgitation occur?
During systole
What are the hemodynamics of mitral regurgitation?
Left atrial pressure can lead to pulmonary edema
Cardiac output falls more if right heart fails
Left atrial volume can lead to atrial fibrillation
Describe aortic stenosis (narrowed)
Diamond shaped– or crescendo and decrescendo
Pressure in ventricle causes ventricular hypertrophy
Very loud (can be felt if severe)
Fairly common
What are the hemodynamics of aortic stenosis?
Left ventricle hypertrophy
Chronic increase in blood volume
When does leaking/regurgitation occur?
Diastole
Describe aortic regurgitation
Blowing murmur–high pitch
Listen over left ventricle for best sound
Short murmur means blood flows back rapidly and is more severe
What are the hemodynamics of aortic regurgitation?
Aortic diastolic pressure decreases rapidly
Filling of ventricle can compress inner parts of heart and coronary artery
Left ventricular hypertrophy
How can a diagnosis of murmurs be done?
Stethoscope or phonocardiogram
Echocardiogram
X-ray
Catheterization
What are congenital murmurs?
Failure of heart formation during gestation
Look at patent ductus arteriosus
Look at patent ductus arteriosus
What can patent ductus arteriosus be treated with?
Prostaglandin blocker, indomethacin
What happens to blood with patent ductus arteriosus?
It recirculates through the lungs
What happens to blood volume with a decreased net cardiac output in patent ductus arteriosus?
It is increased to bring CO back to normal
What happens to cardiac reserve with patent ductus arteriosus?
Decreased
What can patent ductus arteriosus develop?
Pulmonary edema
What are the hemodynamics of patent ductus arteriosus?
Left ventricular hypertrophy
Right ventricular hypertrophy
What happens with interventricular septal defect?
Pan systolic murmur unless hole closes during contraction
The larger the hole the quieter the murmur
Describe interventricular septal defect
Foramen ovale may not fuse closed
May not have normal fibrotic closure of foramen ovale, but left atrial pressure causes it to functionally close
If right atrial pressure becomes greater than left atrial pressure, flowery be reversed
What is tetraology of fallot?
4 abnormalities that results in insufficiently oxygenated blood pumped to the body
What are the 4 abnormalities of tetraology of fallot
Ventrical septal defect (opening between the left and right ventricles)
Displacement of aorta over ventricular septal defect
Narrowing of pulmonary valve
Thickening of wall of right ventricle
