Cardiovascular system pt 6 Flashcards
What are the three types of heart failure?
- Dilated cardiomyopathy
- Hypertrophic cardiomyopathy
- Restrictive cardiomyopathy
What is dilated cardiomyopathy?
Enlarged ventricles and atria that causes a reduced ejection fracture. It is most common and usually caused by injury (heart attack)
What is hypertrophic cardiomyopathy?
Thick and stiff walls of the ventricles causes diastolic disfunction and a decreased output. It can be caused by chronic hypertension
What is restrictive cardiomyopathy?
Wall are stiff but not enlarged. Could be caused by an iron or protein problem in the blood. This is the most rare
What are the causes of heart failure?
- myocardial infarction
- chronic hypertension
- valve disease
- idiopathic
What is the hallmark of heart failure?
Exercise intolerance
What are the classes of HF?
Class I- VO2 max greater than 20
Class II- Vo2max 16-20
Class III- VO2 max 10-16
Class IV- VO2 max 6-10
What are the main outcomes of acute HF?
Decreased stroke volume and cardiac output. Preload and afterload increase while contractility goes down
Describe the feedback system during acute HF?
MAP is lowered due to low SV and Q. This is sensed by baroreceptors which tells the brain that MAP is low. The sympathetic nervous system is stimulated. This will stimulate beta 1 receptors and the HR increases. alpha one and two receptors are stimulated there is an increase in SVR and then SV is increased by increasing preload. PSNS is also decreased to hopefully increase contractility to help raise cardiac output.
What happens in chronic HF?
Cells remodel and hypertrophy and get LV dysfunction. B one gets down regulated and contractility goes down. There is an increase in venous pressure and vasoconstriction.
What are some muscle maladaptation from HF?
- decrease convective O2
- decrease total cap flow
- decrease RBC flux
- decrease capillary hematocrit
- decrease cap/ muscle ration
- decrease surface area for exchange
- decrease O2 driving pressure to mitochondria
- decrease mitochondrial number
What are the causes of the reduced microvascular pressure?
Slow O2 uptake, more intracellular disturbances, and early onset fatigue
What causes edema in HF patients?
i. decompensation and pulmonary congestion
ii. tissue edema formation
iii. increased post capillary pressure
iv. increased cap. hydrostatic pressure
v. increased cap fluid filtration
What does the hydrostatic pressure go to in patients with heart failure?
+1 to +5
What happens when the RAAS system is activated?
The decrease in blood flow to the kidney causes it to released renin. Renin is converted to angiotensin 1. ACE converts this to angiotensin II which causes strong vasoconstriction. It can then be converted to aldosterone which causes Na and Water retention
