Flashcards in Cardiac Failure Deck (37):
What is cardiac failure?
Cardiac failure: failure of the heart to pump enough blood to satisfy the needs of the body.
What are activated during cardiac failure?
Many circulatory reflexes are activated in order to increase activation of sympathetic innervation to the heart and decrease parasympathetic innervation.
During cardiac failure, what does the sympathetic nervous system do?
Sympathetic – strengthens muscle contractions (damaged and undamaged) and increases the tone of muscles, especially VEINS.
How does mean systemic filling pressure change during cardiac failure?
MEAN SYSTEMIC FILLING PRESSURE is increased.
When the heart is damaged, what does it try to increase?
When the heart is damaged, it will increase pressure in order to return to normal cardiac output. If it is too damged, pressure will increase, but the flow will never reach 5 L/min
What is acute effect?
Acute effect: reduced cardiac output, damming of blood in veins -> increased venous pressure. The sympathetic nervous system attempts to compensate this pressure.
What is chronic compensation?
Chronic compensation: results from partial heart recovery and retained fluid. The maxmum pumping ability is reduced. When a person has compensated heart failure, any attempt to perform exercise causes acute failure because the heart is not able to increase its pumping capacity. Increased right atrial pressure maintains the output.
How does pressure change during cardiac failure?
In cardiac failure, mean aortic pressure decreases, and capilary and right atrial pressures increase as they approach zero cardiac output.
What happens to pulmonary pressure during cardiac failure?
As the left side of the heart fails, the right side continues to be pumped into the lungs, but not adequately OUT of the lungs. Pressure in the pumonary system increases due to the large volume present. It is equal to the colloid osmotic pressure. Fluid filters out of the capillaries into the lung intersitialspaces and alveoli, resulting in an edema.
Left heart failure can cause what two conditions?
Two major problems of left heart failure: pulmonary edema and pulmonary vascular congestion. An edema is fatal after 30 minutes.
What is given to patients with cardiac failure in order to increase cardiac output to normal?
Digitalis is given to some patients to help increase the level to 5 L/min or higher.
How does an ateriorvenous fistula affect cardiac output?
Arteriovenous fistula: overloads the heart because of excessive venous return.
How does beri beri affect the heart?
Beriberi: results in a thiamin deficiency, which weakens the heart. The kidneys try to raise pressure via fluid retention, and the venous curve shifts to the right.
What are rheumatic valvular lesions?
Rheumatic valvular lesions: autoimmune disorder in which the valves are destroyed. It is initiated by a streptococcal infection.
What are heart murmus?
Heart murmurs: abnormal heart sounds caused by valvular lesions.
What is an aortic stenosis?
Aortic stenosis: blood is ejected from the left ventricle through only a small fibrous opening of the aortic valve. Resistance to ejection occurs, BP rises to 300 mm HG. It causes severe turbulence of the blood.
What is aortic regurgitation?
Aortic regurgitation: during diasatole, blood flows backward from the high pressure aorta into the left ventricle. IT results from turbulence.
What is mitral regurgitation?
Mitral regurgitation: blood flows backward through the mitral valve into the left atrium during SYSTOLE.
What is mitral stenosis?
Mitral stenosis: blood passes with difficulty through the stenosed mitral valve from the left atrium into the left ventricle. There is little blood in the left ventricle initially, and when it is partially filled, it creates a low rumbling murmur.
what is a left-to-right shunt?
Left-to-right shunt: blood flows backward and fails to flow through systemic circulation.
What is a right-to-left shunt?
Right-to-left shunt: blood flows from right to left side of the heart, bypassing the lungs.
What kind of shunt is patent ductus arteriosis?
Patent ductus arteriosus is a left to right shunt, and teratology of fallot is a right-to-left shunt.
What is circulatory shock?
Circulatory shock is the generalized inadequate blood flow through the body, to the extent that the body tissues are damaged, especially because of too little oxygen and other nutrients delivered to the tissue cells.
What are some cardiac output abnormalities?
Myocardial infarction, toxicity, valve dysfunction, arrythmias, circulatory shock.
What are some venous return abnormalities?
Diminished blood volume, decreased vascular tone of venous reservoirs, obstruction of blood flow.
What receptors are used by the circulatory system as a negative feedback mechanism?
SYMPATHETICS: baroreceptors. Once activated, a decrease in arterial pressure after hemorrhage, decreases in pressures of the pulmonary arteries and veins.
Negative feedback mechanisms/reflexes function to do what?
The reflexes cause arteriole/vein/venous reservoir constriction and increased heart activity.
How does the heart attempt to recover from shock?
Shock recovery: baroreceptor reflex -> sympathetic stimulation -> ischemic response -> higher sympathetic stimulation when BP
`What is moderate shock recovery?
Moderate shock recovery: increases secretion of renin and formation of angiotensin -> vessel constriction, increased retention of fluid and salt.
What hormone is released during moderate shock recovery?
*increased ADH -> artery/vein restriction -> increased retention of water and salt.
What neurotransmitters are released during moderate shock recovery?
*also increased epinephrine & norepinephrine -> constriction of arteries/vessels -> increased heart rate.
How is blood volume returned to normal?
Return of blood volume to normal:
*absorption of large quantities of fluid from the intestinal tract.
*absorption of fluid from the interstitial fluid by the capillaries.
*conservation of water and salt from the kidneys.
*increased thirst and increased appetite for salt.
What is non-progressive shock?
Non-progressive shock: sympathetic reflexes and other factors compensate enough to prevent further deterioration of the circulation. The factors are negative feedback mechanisms that attempt to bring cardiac output and arterial pressure back to normal.
What is progressive shock?
Progressive shock: uses positive feedback mechanisms. When arterial pressure is low, blood flow decreases below that is required to support the tissues of the myocardium. This weakens the heart muscle and decreases cardiac output even more.
*Hemorrhaging affects the outcome.
What is lethal progression of shock?
Lethal progression of shock: vasomotor failure, blockage of small vessels, increased vascular permeability, release of toxins, cardiac depression, cellular deterioration.
*As cells deteriorate, Na/K pumps and mitochondrial activity decreases.
What is neurogenic shock?
Neurogenic shock: shock that occurs WITHOUT loss of blood volume. Massive dilation of blood vessels occurs, and there is not enough blood to fill them.