Patho/Pharm Chapter 27 Heart failure

Cardiovascular diseases

a group of disorders that include heart failure, coronary artery disease, stroke, depp vein thrombosis, peripheral artery disease, and congenital heart disease.

Heart failure

the inability of the ventricles to pump enough blood to meet the body’s metabolic demands. can be caused by any disorder that affect’s the heart’s ability to recieve or eject blood

Heart failure facts in the US

one in every eight deaths have heart failure as a contributing cause

women have a higher mortality rate due to HF than men do

about 50% of people who develop HF die with 5 years of diagnosis

Preload

just before the chambers of the heart contract (systole), they are filled to their maximum capacity with blood. The degree to which myocardial fibers are stretched just prior to contraction

Contractility

the strength of contraction of the heart

inotropic effect

a change in contractility of the heart

afterload

the degree of pressure in the aorta must be overcome for blood to be ejected from the left ventricle

ex: if the mean arterial pressure in the aorta is 80mmHg, the left ventricle must generate a minimum of 81 mmHg to open the aortic valve, and evenn greater pressure to eject blood from the ventricle and push along the pulse wave through the rest of the systemic circulation

positive inotropic agents

drugs that increase contractility EX: epinephrine, norepinephrine, thryoid hormone and dopamine

negative inotropic agents

drigs that decrease contractility Ex: quinidine and beta-adrenergic antagonists, such as propranolol

Increased risk factors

• artherosclerotic cardiovascular disease

• mitral stenosis

• myocardial infarction

• chronic hypertension

• diabetes mellitus

• lipid disorders

• thryroid disorders

right sided heart failure

mechanism: the right side of the heart fails to pump blood into the lungs

pathophysiology: often occurs alongside left-side failure but can occur independently

left sided heart failure

mechanism: the left side of th eheart fails to pump blood efficiently to the body

pathophysiology: the left ventricle enlarges and thickens (hypertrophy) to compensate, but eventially, it cannot handle the increased workload, eading to cardiac remodeling and further dysfunction

Right sided HFsymptoms

1.    Swelling of legs, hands, liver, abdomen

2.    Weight gain

3.    Edema (pitting)

4.    Large neck veins (jugular venous distention)

5.    Lethargic

6.    Irregular heart rate

7.    Nausea

8.    Girth of abdomen increased

Left Sided HF symptoms

1.    Difficulty breathing

2.    Rales

3.    Orthopnea

4.    Weakness

5.    Nocturnal paroxysmal dyspnea

6.    Increased heart rate

7.    Nagging cough

8.    Gaining weight

ACE inhibitors

lowers peripheral resistance (decreased blood pressure) and inhibit aldosterone secretion (reduce blood volume). The resultant reduction of arterial blood pressure diminishes the afterload thus improving cardiac output

adrenergic blockers

decrease cardiac workload by slowing the heart rate and decreasing blood pressure

vasodilators

decrease cardiac worload by dilating vessels and reducing preload.

angiotensin receptor blockers

increase cardiac output by lowering blood pressure and decreasing blood volume

phosphodiesterase

increase cardiac output by increasing the force of myocardial contraction

diuretics

increase cardiac output by reducing fluid volume and decreasing blood pressure

cardiac glycosides

increase cardiac output by increasing the force of myocardial contraction. because of their narrow safety margin and the development of more effective drugs, their use has declined