Module 7 Flashcards
Cardiac Output
volume of blood pumped out of a ventricle in one minute.
CO= SVxHR
Systolic Dysfunction
The heart is unable to eject blood from the ventricle due to impaired myocardial contractility (MI, ischemia, dilated cardiomypathy) or pressure overload (stenosis, hypertension)
Dilated cardiomypathy
condition where the left ventricle of the heart is unable to pump blood properly due to it being enlarged and weakened.
Diastolic dysfunction
The heart is unable to relax (left ventricular hypertrophy, hypertrophic cardiomyopathy, restrictive cardiomypathy) or fill normally (tamponade, MS) due to stiffness
Restrictive cardiomypathy
Walls of the heart are rigid so the heart is unable to stretch and fill normally
hypertrophic cardiomypathy
a primary disease of the myocardium where the wall is thickened without obvious cause. The cardiac muscle is functionally impaired. (leading cause of sudden cardiac death in young athletes)
Ventricular hypertrophy
thickening of ventricular walls
Right heart failure
most commonly associated with left heart failure. However on its own it is usually the result of lung diseases (parenchymal pulmonary disease or pulmonary vascular disease)
Right ventricle is vulnerable to failure as a result of acute pulmonary embolism
Compensatory mechanisms to preserve CO when increased work is put on the heart
Frank-Starling mechanism, neurohormonal alterations, ventricular hypertrophy and remodelling.
Frank-Starling mechanism
Cardiac fiber will contract with greater force if stretched prior to contracting producing greater stroke volume to preserve CO
Neurohormonal transmitters
mechanisms that maintain cardiac output include: Adrenergic nervous system, renin-angiotensin-aldosterone system and increased production of ADH.
Ventricular hypertrophy and remodelling
occurs over a period of time. The heart muscle thickens as a result of the heart pumping against high pressures and dilates due to volume overload.
What factors precipitate symptoms of heart failure
1) Increased afterload (increasing resistance to ejecting of blood from Ventricles)
2) Increased preload (increasing volume of blood to be pumped)
3) Impaired atrial emptying
4) Impaired systolic function (reducing myocardial contractility)
5) Increased metabolic demands (for blood by peripheral tissues)
Signs of left heart failure
diaphoretic (sweating) tachypnea (rapid breathing) tachycardia pulmonary rales loud P2, S3 gallop
Signs of right heart failure
jugular venous distention
hepatomegaly (enlarged liver)
peripheral edema
Left heart failure symptoms
dyspnea(laboured breathing)
orthopnea (shortness of breath while lying flat)
Paroxysmal nocturnal dyspnea(attacks of shortness of breath usually happening at night)
Fatigue
Right heart failure symptoms
Peripheral edema
Upper right quadrant discomfort
What attributes to the rising prevalence of heart failure?
- An aging population- heart failure usually happens in people who are over 50 years old.
- Revascularization and thrombolytic therapy- because of these therapies individuals can now survive an acute event, they are left with some myocardial damage which can attribute to heart failure later.
Methods to diagnose heart failure
Chest X-ray
BNP- B type natriuretic peptide- produced when ventricular myocardium is subject to hemodynamic stress
History
Echocardiogram- calculate ejection fraction and visualize systolic and diastolic function
what is that goal of chronic heart failure treatment?
identify and correct underlying etiology eliminate the precipitating cause of symptoms manage heart failure symptoms modulate the neurohormonal response improve long term survival
Phamacological treatment of chronic heart failure
ACE inhibitors- effect on remodeling
Beta blockers- enhance relaxation, lower HR, longer diastole filling time
Coumadin- cause anticoagulation
Cardiac inotropes- enhance force of ventricular contraction
Diuretics- promotes elimination of sodium and water(D. venous return)
Digoxin- enhances contractility
Pharmacological treatment of diastolic dysfunction
ACE inhibitors
calcium channel blockers
diuretics
Lifestyle modification (CHF)
Reduced sodium diet
limited fluid intake
Regular exercise tailored to patients tolerance level
Heart transplant and mechanical treatments for CHF include:
Heart transplant
Implantable cardiac defibrillator (ICD)
Cardiac resynchronization
Left Ventricular Assist Device (LVAD)
Treatment of acute heart failure
Goal: increase oxygenation and reduce left heart filling pressures
Treatment: Vasodilators (nitroglycerine), upright position, oxygen, morphine, loop diuretics (furosemide, bumetanide, torsemide), inotropic drugs (dopamine, dubutamine), and nitroprusside in patients with severe MR or AR
What can cause increased afterload?
arterial hypertension
aortic stenosis
pulmonary valve stenosis
What can cause increased preload?
left to right shunt
severe valvular regurgitation
impaired atrial emptying can be caused by
mitral stenosis
tricuspid valve stenosis
Impaired systolic function can be caused by
myocardial ischemia
myocardial infarction
dilated cardiomypathy
What causes increased metabolic demand
pregnancy
hyperthyroidism
tachycardia
anemia
