Cardiac Muscle Dysfunction Flashcards
What condition impairs the heart’s ability to pump or receive blood?
Cardiac Muscle Dysfunction
List characteristics of CMD (read)
- Ejection fraction is 30-40%
- Angina and myocardial ischemia is brought on by lack of O2 supply/demand to heart
- Cardiac arrhythmias from decreased myocardial function
- Myocardial infarction
- Hypertension
- Myocardium stiffens
- LV weakens and dilates
- Renal insufficiency
What is the most common cause of CHF?
Cardiac muscle dysfunction from dilated cardiomyopathy
How is CHF manifested?
Pulmonary congestion or edema
What is the most common cause of CMD?
MI
What is cardiomyopathy?
Abnormality of heart muscle
How is the heart affected from cardiomyopathy?
Lack of pumping of the heart - contraction/relaxation issues
What happens to the heart as it compensates for cardiomyopathy?
It becomes larger - cardiomegaly
What does ischemic cardiomyopathy result from?
From coronary artery disease
What does nonischemic cardiomyopathy result from?
Disease of heart muscle itself:
- Dilated
- Hypertrophic
- Restrictive
What are the three types of cardiomyopathy?
Dilated
Hypertrophic
Restrictive
Dilated cardiopathy is [idiopathic/non-idiopathic]
Idiopathic
What age group is typically affected by dilated cardiomyopathy?
Middle-aged
Men > Women
What are causes of dilated cardiomyopathy?
Family genetics
Viral infection
Alcoholism
Toxins
Cancer drugs
Pregnancy and childbirth
Smoking
Describe structural changes of dilated cardiomyopathy.
Dilated left ventricle and atrium
Bulging interventricular septum from left to right
Thin ventricular walls
Myocardial mitochondria dysfunction
How does heart function change due to dilated cardiomyopathy?
Ineffective/inefficient pumping
Heart is working at end-range, not enough cardiac output
Describe structural changes of hypertrophic cardiomyopathy.
Increased thickness of LV wall
Increased thickness of interventricular septum
Decreased LV cavity size
How does heart function change due to hypertrophic cardiomyopathy?
Exaggerated pump function (hypercontractile systolic function)
Poor heart relaxation (diastolic dysfunction)
What type of cardiomyopathy is rarest?
Restrictive
What type of cardiomyopathy has the worst prognosis?
Restrictive
Describe structural changes of restrictive cardiomyopathy.
Stiffened wall of ventricles with loss of flexibility due to infiltration by abnormal tissue
What are signs to look for CHF?
- Cardiac silhouette (ball sack) on chest x-ray
- Fluid in lungs
- EF < 30%
- Cold, cyanotic extremities
- Abnormal S3 heart sound
- Sinus tachycardia
- Quick, shallow breaths
- Peripheral edema
- Crackles/Rales during inspiration
- Systolic BP with controlled expiratory maneuver
- Jugular vein distension (JVD)
- Decreased exercise tolerance
What is an abnormal S3 sound indicate?
LV is non-compliant and poor relaxation during diastole
What are symptoms that patients will report indicating CHF?
Dyspnea
“difficulty breathing”
Why does dyspnea occur?
- Poor gas transport due to acute/chronic pulmonary edema
- Abdominal ascites from peripheral edema and limited diaphragm descent
- Ventilatory muscle weakness
- Lack of O2 supply from increased tidal volume and RR
What symptom will patients report at night due to CHF?
Paroxysmal nocturnal dyspnea and orthopnea
“suddenly can’t breathe that wakes me up at night”
How should be position patient with paroxysmal nocturnal dyspnea/orthopnea?
- HOB propped up in bed or chair
- Avoid lying supine
Why is digitalis (Digoxin) used for treatment?
- Blocks the Na/K pump to activate Na-Ca exchange
- Leads to increased myocardial contractility
- Increases renal perfusion (diuretic effect)
- Relief symptoms of heart failure
- Decreases sympathetic influence on heart and increases parasympathetic activity (thru AV node)
What are side effects of digitalis?
Bradycardia
Fatigue, nausea
ST segment depression, 1st degree block, PVS< V-tach, A-fib
Slightly toxic if dosage increased
How does digitalis help with exercise?
Improve LV function
Improve EF
