Cardiovascular Flashcards
In fetal circulation where is the foramen ovale located?
Between right and left atrium
How does fetal circulation work?
IVC ➡️ RA ➡️ foramen ovale ➡️ Aorta
SVC ➡️ PDA ➡️ aorta
What causes fetal shunts to close?
- Increased arterial oxygen tension
- Decreased prostaglandins
- Decreased adenosine levels
When does the fetal shunts start to close?
When baby takes its first breath due to increased PVR
When does the PDA start to close?
Closure is within 10 to 24 hours
When does foramen ovale start to close?
When the pressure in the RA is less than the pressure in the LA
What is cardiac output?
- Volume of blood pumped by the heart and one minute
- Measures hearts efficiency
- Stroke Volume x Heart Rate
What is the cardiac output in a normal newborn?
200 mL/kg/min
Children has higher CO then adult due to increased heart rate
What is preload?
- End of diastole
- Elasticity when the ventricles are filled to the maximum
- Volume
What can cause decrease in preload?
Dehydration
Vasodilation
What is afterload?
- Pump
- Resistance against which the ventricles must pump
- The work that the heart has to do to push blood into the aorta and around the body or into the lungs
What is contractility?
- Squeeze
2. Amount of force exerted with each contraction
What causes contractility?
Hypoxemia
What is the conduction of the heart?
SA node
AV node
Bundle of His
Purkinje fibers
What does the Purkinje fibers do?
It causes LV to contract
What is congestive heart failure?
A syndrome in which the heart cannot pump an adequate amount of oxygenated blood to meet the metabolic needs of the body
What are the two types of heart failure?
Right sided heart failure
Left sided heart failure
What is right-sided heart failure?
The right ventricle is not able to efficiently pump blood into the pulmonary artery therefore the right side of the heart becomes congested and backs up into the veins and the body
What is left-sided failure?
Left ventricle is not able to pump blood into the aorta and systemic circulation resulting in increased pressure in the left atrium and pulmonary veins and goes back into the lungs
Causes of CHF in children
- Structural abnormalities
- Myocardial failure
- Excessive demands on the normal heart muscle
Hypoxemia
An arterial oxygen tension (of pressure, PaO2) that is less than normal and can be identified by a decreased arterial oxygen saturation or a decreased PaO2
Hypoxia
Reduction in tissue oxygenation that results from low oxygen sats and paO2 and results in impaired cellular processes
Define shock
Circulatory failure - inadequate perfusion to meet metabolic needs of the body
What would happen to the BP on initial shock?
Increased BP d/t initial vasoconstriction
3 signs of shock
Hypotension
Hypoxemia
Metabolic acidosis
Compensated shock
Vasoconstriction caused by sympathetic nervous system
Normal BP, might be a little high
Provides blood to vital organs
Cold, clammy skin
Decreased bowel sounds
Decreased urinary output
Lactic acid increases - inc metabolic acidosis
Uncompensated shock
Compensation fails and the cv system can no longer maintain perfusion to the microvasculature
Manifestations of uncompensated shock
Hypotension Rapid respiration Tachycardia Mental status changes Increased BUN and creatinine Liver enzymes increase DIC
Types of shock
Cardiogenic shock
Hypovolemic shock
Obstructive shock
Distributive shock
Cardiogenic shock
Ineffective pumping mechanism of the heart
Decreased CO and increased SVR caused by inc afterload, dec contractility
Hypovolemic shock
Most common type in children Dec in intra vascular body by 15-25% ⬇️ preload ⬆️ afterload No change in contractility
Obstructive shock
Severe obstruction to ventricular filling or outflow
Ex. Tension pneumothorax or PE
Distributive shock
Abnormal distribution of blood volume
⬇️ SVR d/t massive vasodilation
Blood shunts pass capillary beds
Three types of distributive shock
Septic
Anaphylactic
Neurogenic
What is anaphylactic shock
Vasodilation from release of mediators: IgE Histamine Serotonin Bradykinin PGR
Neurogenic shock
Loss of sympathetic vasomotor tone leads to extreme visit dilation
Can be a complication of brain or spinal cord injury
In a child diagnosed with cardiac hypertrophy, the heart muscle enlarges due to:
⬆️ in the size of myocytes
Cardiomyopathy
Disease of the heart muscle
Myocyte degeneration occurs because of
Changes in the myocardium
Decreased contractility occurs because of
Scarring
The most common cause of sudden cardiac death and young healthy athlete is
Hypertrophic cardiomyopathy
Three types of cardiomyopathy
Hypertrophic
Dilated
Restrictive
What is commotio Cordis
Sudden hit in chest that causes lethal arrhythmia
40% Most often seen in infants and teens Autosomal dominant Hypertrophied nondilated left ventricle Left ventricular outflow tract obstruction ⬆️ size and thickness of left ventricle ⬇️ LV filling Syncope is most common sign d/t arrhythmia
Hypertrophic cardiomyopathy
Name a few causes of dilated cardiomyopathy
Idiopathic
Myocarditis
Genetic
CHF from dilated left ventricle and systolic dysfunction ⬆️ ventricular chamber size ⬆️ myocardial stretch ⬇️ contractile force ⬆️ ventricular end diastolic pressure ⬆️ diastolic volume ⬇️ stroke volume
Dilated cardiomyopathy
Least common type of cardiomyopathy
Minimal contractile movement
Ventricular walls become stiff and prevent the heart from filling with blood
⬇️ ventricular compliance
Restrictive cardiomyopathy
Manifestations of cardiomyopathy
Enlarged heart Contractility changes Signs of CHF Poor perfusion Changes in heart sounds especially Gallop Arrhythmias risk of emboli Chest pain Syncope
Medicines for hypertrophic cardiomyopathy
Beta adrenergic agonist ⬇️ ventricular workload
Inotropes: used cautiously
Ca Channel blocker ⬇️ afterload and Contractility
Medicines for dilated cardiomyopathy
Digoxin: ➕ inotropes: ⬆️ contractility
Beta blockers: counter sympathetic stimulation
Surgery for cardiomyopathy includes
Ventricular septal myotomy
Pacing
Fluid and Na restrictions
Transplantation
