3.5 CHF Pathophysiology
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3.5 CHF Pathophysiology
What can increase contractility?
Increased sympathetic stimuli
Hormones - Epinephrine and Thyroxine
Ca2+ and some drugs
Intra- and extracellular ion concentrations must be maintained for normal heart function
Sympathetic stimulation of contractility releases what and initiates what system?
Initiates a cAMP second-messenger system
What cells release Renin?
Where is Angiotensinogen released from?
Where does ACE come from?
Is Angiotensin II a vasoconstrictor or vasodilator?
What does Angiotensin II help release?
Argenine Vasopressin (ADH)
What does Aldosterone do?
Na and Water Retention
What does ADH do?
What 4 things determine cardiac function?
Contractile state of the heart muscle
Preload (end-diastolic volume and the resulting length of the cardiomyofibers prior to the onset of contraction)
Afterload (resistance to the ventricular ejection of blood)
What are the cardiac characteristics of a Left Sided Heart Failure?
Ineffective left ventricular contractility
Decreased LV pump
Back up of volume in LA and back to lungs
What are the symptoms of left sided heart failure?
Paroxysmal Nocturnal Dyspnea
- can't sleep at night when lying flat
Elevated Pulmonary Capillary Wedge Pressure
Pulmonary congestion (Cough, Crackles, Wheezes, Blood-Tinged Sputum, Tachypnea)
What are the cardiac characteristics of a Right Sided Heart Failure?
Ineffective right ventricular contractility
Decreased RV pump
Back up of volume on venous side
What are the symptoms of Right Sided Heart Failure?
Back up to vital organs - liver, spleen
↑ Peripheral Venous Pressure
May be secondary to chronic pulmonary problems
Distended Jugular Veins
Anorexia and Complaints of GI Distress
What is a systolic dysfunction?
Ventricular Chambers are large
Lack of good Starling Effect, won't pump with good contractile force
What is a diastolic dysfunction?
Problem with filling of stiffened ventricles
Due to remodeling became stiffened
What are the causes of Systolic Dysfunction?
Coronary Artery Disease (CAD)
What are the causes of Diastolic Dysfunction?
Coronary Artery Disease
What is preload?
Volume of blood in ventricles at end of diastole (end diastolic pressure)
When is preload increased?
Regurgitation of cardiac valves
What is afterload?
Resistance left ventricle must overcome to circulate blood
When is afterload increased?
What are 3 causes of CHF?
What drugs do you give to increase contractility and how does it work?
Inhibits Na/K ATPase Pump
What are the symptoms for Digitalis Toxicity?
Loss of appetite
Nausea, vomiting, diarrhea
Vision changes (unusual), including blind spots, blurred vision, changes in how colors look, or seeing spots. Halos of white and green colors
What happens if you slow down the Na/ K ATPase Pump?
How do you decrease preload?
↓ Salt intake
↓ water intake (1200 mls/day)
Give diuretics to decrease edema. Give K+ sparing (over K+ wasting) due to possibility of hypokalemia
How do you decrease afterload?
Give β-blockers - reduces BP caused by body trying to ↑ CO
Will ↓ BP
Give ACE inhibitors to ↓ angiotensin II formation
Give diuretics to ↓ BP
What do you give when CHP is due to Coronary Artery Disease and how does it work?
Vasodilate the coronary arteries and ↑ oxygenation to the myocardium which will ↑ contractility and ↓ preload and afterload
What is an acronym to treat CHF?
Test (Dig level, ABGs, K+ levels)
What are symptoms of late stages of CHF?
Skin pale, gray, or cyanotic
Dyspnea, Orthopnea, Crackles, wheeze, cough
Nausea and vomiting
Dependent, pitting edema
Falling O2 saturation
Jugular vein distention
S3 gallop, tachycardia
Enlarged spleen and liver
Decreased urine output
Cool, moist skin
Why does the heart hypertrophy during CHF?
According to the Law of Laplace, best way to ↓ LVP is to ↑ the wall thickness
Denominator is ↓ the LVP value
↓ Radius helps offset the effects of an ↑ LVP