lecture 12: Cardiac failure Flashcards
What is heart failure?
occurs when the heart cannot supply sufficient blood to the vital organs of the body: results in Coronary Artery Disease, Hypertension, Dilated Cardiomyopathy.
What is a Cardiac reserve?
Refers to the difference between cardiac output at rest vs. maximum capacity. Athletes have large cardiac reserve (5-6 times resting heart rate output). People with CHD do not have significant reserve volume. CHD is characterized by an inability to increase CO.
what is the equation for cardiac output?
HR x SV
what is ejection fraction?
the volume of blood pumped out by the ventricles with each heartbeat.
name the two types of heart failure?
- systolic ventricular dysfunction
2. diastolic ventricular dysfunction
explain systolic ventricular dysfunction as a result of heart failure?
the Contractility is impaired so the ejection fraction is DECREASED so CO is decreased
explain diastolic ventricular dysfunction as a result of heart failure?
the diastolic filling is decreased so EDV is decreased so CO is decreased.
Causes of systolic ventricular dysfunction?
Impaired contractile function → MI, ischemia, cardiomyopathies
What’s the ‘fall out’ of decreased contractility?
End diastolic volume? → INCREASED
Atrial volume? → INCREASED
Systemic and pulmonary circulation? → INCREASED WITH CONGESTION
BACKING UP → E.g. LEFT systolic dysfunction heart failure = pulmonary congestion
Causes of Diastolic Dysfunction and HF?
Impaired diastolic filling → E.g Pericardial effusion, hypertrophy (chamber size); delays in relaxation (aging, ischemia); heart rate increase (tachycardia increases disease progression
What is going to happen to the pressure of the left ventricle?
INCREASED (COMPENSATORY)
Can you see the potential for pipe clogging?
Yes, pressure is high, hard for fluids to get into the ventricle
What are the implications for the lung?
Congestion
most common cause of right-sided failure?
Left-sided failure causes right-sided failure (most common cause)
PATHOPHYSIOLOGY of Right-Sided Heart Failure
Right ventricle output is decreased or lost.
What might the effect be on total cardiac output, right ventricle pressure, right atrial pressure, and systemic pressure when you have right-sided heart failure?
increased for all.
most common cause of hypertension?
most common cause of hypertension is left-sided heart failure
pathophysiology of left-sided heart failure (LSHF)
decreased in the output of the right ventricle. with this there is an increase in all pressure and cardiac output is increased as well.
effect of LSHF on tissue perfusion?
decrease.
effect of LSHF on pulmonary fluid?
build up
Why does increased pulmonary pressure result in pulmonary edema?
When you have left ventricular failure, blood starts to accumulate in the left ventricle, left atrium, pulmonary circulation. Pressure starts to increase in pulmonary circulation (normally 10mm Hg). If it exceeds the capillary osmotic pressure (usually 25mm Hg) then there will be a possibility of fluid moving into the interstitial fluid; edema.
list the respiratory manifestation of heart failure?
pulmonary edema which leads to fluid in lungs and lungs stiffness and impaired gas exchange.
what is circularory shock?
inability to properly perfuse tissues.
obstructive Shock
due to obstruction of blood flow outside of the heart.
Distributive shock
excessive vasodilation causing the impaired distribution of blood flow
types of distributive shock?
septic and anaphylactic shock
septic shock
Infection with a microorganism resulting in the production of a massive amount of cytokines.
Increased vascular permeability → decreased blood pressure.
anaphylactic shock
Response to an allergen, antigen or drug, resulting in a inflammatory response and the production of histamine → Vasodilator
