-
automaticity
spontaneaous depolarization (contraction) of heart cells
-
cardioglycosides
class of drugs, most commonly derived from the foxglove plant that have the ability to alter cardiovascular function. Digitalis is representative of this class of drugs
-
digitialization
process of rapidly increasing the initial dose of digoxin until the therapeutic dose is achieved
-
ejection fraction
percentage of blood ejected from the left ventricle with each heart beat
-
heart failure
clinical syndrome in which the heart is unstable to pump blood at a rate to meet body's metabolic needs
-
natriuretic peptides
hormones that play a role in cardia homeostasis
-
positive inotropic effect
increase the force of myocardial contractions
-
stroke volume
equal to amount of volume ejected by the left ventricle during each cardiac contraction minus the vloume in the ventiricle at the end of systole
-
heart failure primarily affects the elderly affecting more that 10% of the populations over 50 years compared to 1% under the age of 50.
-
up to age 75, the prevalence of heart failure is higher in men, but after age 75, the prevalence is higher in women
-
disease, lifestyle, and drugs can contribute to the onset or aggravation of heart failure
-
kidney dysfunction, bradyarrythmia, tachyarrythmia, pulmonary embolism, HIV/AIDS, and myocardial infarction contribute to heart failure
-
heart failure can be worsened by lack of physical activity, and excessive alcohol and salt consumption
-
NSAIDs worsen edema, and interfere with the drugs used to treat heart failure (e.g., ACEIs)
-
heart failure may affect left side, right side, or both sides of heart
-
left-sided heart failure reduces the volume of O2 and nutrient-rich blood pumped from the left ventricle to the reast of the body
swelling in legs, ankles, fatigue
fluid accumulation resulting in weight gain and increased urination
-
right-sided failure reduces capacity of the heart to pump blood to the lungs
fluid backs up (venous congestion) and cause pulmonary edema and shortness of breath
BP increases
-
heart failure classified as systolic heart failure (SHF) or diastolic heart failure (DHF)
choice of drug therapy is influenced by whether the patient has SHF or DHF
-
four stages of heart failure
- stage A: high risk for developing heart failure
- stage B: structural changes without symptoms
- stage C: symptomatic
- stage D: advanced structural heart disease plus heart failure symptoms
-
in SHF, left ventricle contractions are reduced causing a decrease in the vol of blood ejected from the ventricles (stroke volume)
results in reduced CO
-
in DHF, stroke volume is reduced because the left ventricle is unable to accept a sufficient volume of blood during diastole
CO is reduced, causing:
- fatigue
- dyspnea
- pulmonary hypertension
-
compensatory mechanisms are "switched on" when the heart function fails, RAAS attempt to satisfy the metabolic needs of the body and to reduce elevated BP
RAAS activation results in increase of blood vloume and CO
-
natruietic peptides are hormones that also play a role in cardia physiology, their release is also a compensatory mechanism in heart failure
-
Natriuretic peptidesare released.–Atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) promote sodium and water elimination, vasodilation, and diastolic relaxation.
-
-
-
most treatments used in heart failure focus on treating symptoms, underlying causes, and factors that worsen heart failure
-
many of the same drugs adminstered in the treatment od hypertension are also used in the treatment of heart failure
β-blockers, ACEIs, ARBs, diuretics, aldosterone antagonists
-
cardioglycosides are the oldest class of drugs in the treatment of heart failure
-
Statins are also administered in the treatment of heart failure
-
according to DIG studies, digitalis fails to increase survival in patients with heart failure
-
digoxin may actually increase mortality in women
-
digoxin should be administered with ACEIs, diuretecs, and or β-blockers
-
cardioglycosides (e.g., digoxin) have a positive inotropic effect on the heart
they increase the force of mycardial contractions
the greater force of contractions increases cardiac output
-
digoxin ADRs
- Diarrhea
- Constipation
- Nausea and vomiting
- Fatigue
- Weakness
- Visual disturbances (altered color perception, hazy vision)
- Photophobia
- Impotence
- Gynecomastia
-
Digoxin increases cardiac output and decreases compensatory sympathetic activity. which results in slowed heart rate
It is the only commercially available cardioglycoside.
-
Signs of digitalis toxicity are arrhythmia, dizziness, headache, convulsions, delusions, and coma.
-
patient must be monitored carefully for signs of digitalis tocicity because digoxin has a narrow TI,
initail dose should be half, followed by 1/4 in 8-12 hrs, and final 1/4 about 8-12 hrs later
-
bioavailability of digoxin varies by manufacturer, so switching between manufacturers is not recommended
food also can decrease digoxin absorption
-
digoxin not recommended for treatment of DHF in men or women, especially if sinoatrial or AV bloack is present
-
diuretics are used to treat volume overloads
they also lower BP
-
loop and thiazide diuretics can cause hypokalemia, which can cause ventricular arrythmias and increase the effects of digoxin leading to toxicity
-
β-blockers reduce HR, lower PR, and decrease the workload of your heart, reduce left ventricular hypertrophy
-
studies show that β-blockers can lower the risk of mortality associated with congestive heart disease
-
β-blockers block excess sympathetic stimulations induced by heart failure
-
CCBs may be used in the treatment of DHF because they can control HR, lower BP, and treat ischemia-- risk factors for congestive heart failure (CHF)-- and reduce left ventricular hypertrophy
-
CCBs should not be administered for the treatment of SHF because they can make ventricular contractions worse, further reducing cardiac output
-
ACEIs have been shown to reduce mortality rate (prolong life).
-
ACEIs reduce left ventricular hypertrophy, improve diastolic filling, increase CO, reduce peripheral vascular resistance
-
ARBs are also administered for the treatment of heart failure
they improve exercise tolerance and diastolic fillling in patients with DHF
-
administration of statins is associated with increased survival in patients with heart failure with ischemic disease buit increased mortality when total cholesterol levels are low and ischemic disease is absent
-
isosorbide dinitrate and hydralazine are used in combination for the treatment of heart failure for their vasodialating effects
together they decrease mortality and effectively reduce cardiac congestion
|
|
