ch 34 HF Flashcards
is a complex clinical syndrome that develops in response to myocardial insult
Heart failure (HF)
results in the inability of the heart to provide sufficient blood to meet the oxygen (O2) needs of tissues and organs. The decreased cardiac output leads to decreased tissue perfusion, impaired gas exchange, fluid volume imbalance, and decreased functional ability.
Heart failure (HF)
percentage of the total blood volume in the left ventricle (LV) at the end of diastole that is pumped out of the LV with the next systole is called the l
left ventricular ejection fraction (LVEF)
a defect in either ventricular systolic function/LV contraction (heart failure with reduced ejection fraction [HFrEF]) and/or a defect in ventricular diastolic function/filling (heart failure with preserved ejection fraction [HFpEF]).1
HF manifestations occur due to
HTN and CAD are the
primary risk factors for HF.
congenital abnormalities (e.g., septal defects), infiltrative cardiomyopathies (e.g., sarcoidosis), infections and inflammatory processes (e.g., viral myocarditis), persistent dysrhythmias, and toxins (e.g., alcohol, drug use, chemotherapy).3
other causes of HF
(1) preload, (2) afterload, (3) myocardial contractility, and (4) HR
CO depends on
(1) primary causes
(2) precipitating causes
major causes of HF are divided into 2 subgroups:
often increase the workload of the heart, resulting in an acute condition and decreased heart function.
Precipitating causes
(heart muscle cell)
cardiomyocyte
responds to such a mutated gene.
body’s largest known protein, titin,
impair sarcomere function and disrupt chemical signaling, which negatively affects ventricular structure and stability.
Titin mutations
activated in response to myocardial dysfunction, leading to remodeling of myocardial structure and function (Fig. 34.1).
Manifestations of HF are the result of neurohormonal compensatory mechanisms
- Cardiomyopathy (e.g., viral, postpartum, substance use)
- Congenital heart defects (e.g., ventricular septal defect)
- CAD, including MI
- HTN, including hypertensive crisis
- Hyperthyroidism
- Myocarditis
- Pulmonary HTN
- Rheumatic heart disease
- Valvular disorders (e.g., mitral stenosis)
Primary Causes of Heart Failure
Systolic HF
(heart failure with reduced ejection fraction [HFrEF])
diastolic HF
(heart failure with preserved ejection fraction [HFpEF]).1
, results either from the inability of the LV to (1) empty adequately during systole or (2) fill adequately during diastole. We can further classify left-sided HF as HFrEF (systolic HF), HFpEF (diastolic HF), or a combination of the two.
most common form of HF, left-sided HF
an inability of the heart to pump blood effectively.
HFrEF results from
is 55% to 65%
Normal LVEF
< 40%
-can be as low as 5% to 10%.
Patients with HFrEF generally have an LVEF
impaired contractile function (e.g., MI), increased afterload (e.g., HTN), cardiomyopathy, and mechanical abnormalities (e.g., valvular heart disorders).3
HFrEF is caused by
Over time, the LV becomes dilated and hypertrophied.
LV in HFrEF loses the ability to generate enough pressure to eject blood forward through the aorta.
the inability of the ventricles to relax and fill during diastole.
HFpEF results from
(1) signs and symptoms of HF, (2) normal LVEF, and (3) evidence of LV diastolic dysfunction by echocardiography or cardiac catheterization
diagnosis of HFpEF is based on (HTN is the primary cause of HFpEF.)
↓ O2-carrying capacity of the blood stimulating ↑ in CO to meet tissue demands, leading to increase in cardiac workload and increase in size of LV
anemia
Infection: ↑ metabolic demands and O2 requirements
Valvular dysfunction: causes stenosis or regurgitation
Bacterial endocarditis
May ↓ CO and ↑ workload and O2 requirements of myocardial tissue
Dysrhythmias
Hypervolemia
↑ Preload causing volume overload on the RV
Indirectly predisposes to ↑ atherosclerosis. Severe hypothyroidism decreases myocardial contractility.
Hypothyroidism
Have HFpEF more often than men.
• HTN is the most common cause of HF in women.
-Higher risk of ACE inhibitor–related cough than men.
women HFpEF
- Have HFrEF more often than women.
- Ischemic heart disease (MI, CAD) is the most common cause of HF in men.
- ACE inhibitor therapy reduces mortality more in asymptomatic.
men HFrEF
of any type may have low BP, low CO, and poor renal perfusion
ventricular failure vitals
occurs when the right ventricle (RV) does not pump effectively.
Right-sided HF
movement of fluid into the tissues and organs (e.g., peripheral edema, abdominal ascites, hepatomegaly, jugular venous distention[JVD]).
When the RV fails, fluid backs up into the venous system. This causes
is left-sided HF.
most common cause of right-sided HF
LV fails, fluid backs up into the pulmonary system, causing increased pressures in the lungs. The RV must work harder to push blood to the pulmonary system. Over time, this increased workload weakens the RV and gradually it fails
most common cause of right-sided HF reasoning
(independent of the function of the LV) include RV infarction, pulmonary embolism, and cor pulmonale (RV dilation and hypertrophy caused by pulmonary disease)
Other causes of right-sided HF
includes both LV and RV dysfunction, the inability of both ventricles to pump effectively. Because of decreased contractility, fluid build-up and systemic venous engorgement occur.
Biventricular failure
include (1) neurohormonal responses: renin-angiotensin-aldosterone system (RAAS) and the sympathetic nervous system (SNS); (2) ventricular dilation; and (3) ventricular hypertrophy.
2 main main compensatory mechanisms for HF
is augmentation of preload and ventricular contractility to maintain CO.
goal of RAAS activation
retention of fluid and sodium
RAAS activation promotes
juxtaglomerular apparatus in the kidneys senses decreased renal perfusion from a falling CO. In response, the kidneys release renin, which converts angiotensinogen to angiotensin I. Angiotensin I is next converted to angiotensin II by a converting enzyme made in the lungs. Angiotensin II is a potent vasoconstrictor that stimulates renal water and sodium retention and the release of aldosterone from the adrenal gland. Aldosterone acts in the nephron to stimulate sodium retention and potassium excretion and promoting myocardial fibrosis in the failing heart.
pathophysiology of RAAS
stimulated by response to arterial low pressure/under filling via baroreceptor signals
ADH regulates water retention by stimulating renal tubular reabsorption.
stiff hard muscles
fibrosis
(programmed cell death)
myocyte apoptosis
such as cardiac myocyte apoptosis (programmed cell death), hypertrophy, and fibrosis
Chronic activation of the RAAS can cause harmful effects
stimulating the SNS to try to maintain
Baroreceptors sense low arterial pressure
(epinephrine and norepinephrine)
Catecholamines (SNS)
Baroreceptors sense low arterial pressure, stimulating the SNS to try to maintain CO. Catecholamines (epinephrine and norepinephrine) are released. Stimulation of β-adrenergic receptors increases HR (chronotropy) and ventricular contractility (inotropy). Ultimately, chronic SNS stimulation increases myocardial O2 demand on the already weakened heart.
SNS compensation process
(RAAS and SNS)
neurohormonal responses
high levels of ADH, endothelin, and proinflammatory cytokines. Together, these factors further increase in the heart’s workload, intensify ventricular dysfunction, and force ventricular remodeling.
Continuous activation of the neurohormonal responses (RAAS and SNS) in HF leads to
, a vasoconstrictor peptide made by the vascular endothelial cells, is stimulated by hypoxia, ischemia, neurohormones, and inflammatory cytokines.
Endothelin
, acting as a negative inotrope. This serves to decrease ventricular contractility in the failing heart.
endothelin stimulates contraction in most smooth muscles, it has the opposite effect on the heart
are released by myocytes in response to heart injury (e.g., MI, HF)
Proinflammatory cytokines
exerting a negative inotropic effect, causing myocyte hypertrophy and apoptosis.
Two cytokines, tumor necrosis factor (TNF) and interleukin-1 (IL-1), further depress heart function by
in an increase in the heart’s workload, progressive LV dysfunction, myocyte hypertrophy, and ventricular remodeling.
High levels of endothelin and proinflammatory cytokines result
is an enlargement of the heart chambers
Dilation
occurs when pressure in the heart chambers (usually the LV) is elevated over time.
Dilation
, the strength of the heart’s contraction is directly proportional to its diastolic expansion. The implication is that increased preload (a greater influx of blood into the ventricle during diastole) will cause a more forceful contraction
Frank-Starling Law
cardiac muscle fibers are overstretched, and further increases in preload no longer increase CO.
excessive preload exhausts the Frank-Starling mechanism,
is an adaptive increase in the muscle mass and heart wall thickness as a slow response to overwork and strain
Hypertrophy
Initially, the increased contractile power of the muscle fibers leads to an increase in CO and maintains tissue perfusion. Over time, hypertrophic heart muscle has poor contractility, needs more O2 to perform work, has poor coronary artery circulation (tissue becomes ischemic more easily), and is prone to dysrhythmias.
Hypertrophy compensation process
occurs over time in response to pressure or volume overload and/or cardiac injury and the subsequent compensatory mechanisms.
Ventricular remodeling in HF
is an actual change in the structure (dimensions, mass, shape) of the heart
Pathologic ventricular remodeling
neurohormonal (RAAS& SNS), ET (endothelin), and cytokine (pro inflammatory) activation and ventricular adaptations, including dilatation and hypertrophy.
ventricular remodelling compensating mechanism include
increased ventricular mass, increased wall tension, increased O2 consumption, and impaired contractility.
altered shape of the ventricles eventually leads to
- become less effective pumps.
- The LVEF further declines due to loss of mechanical advantage from altered ventricular geometry.
ventricular remodelling outcome
Increases in angiotensin II, aldosterone (increase bp/preload), and cytokines stimulate collagen (inflammation) synthesis leading to fibrosis (stiff muscle) and further impaired pumping ability.
ventricular remodelling declining results
dysrhythmias and sudden cardiac death (SCD).
Ventricular remodeling is a risk factor for life-threatening
ACE inhibitors (stop RAAS), β-adrenergic blockers (β-blockers), and aldosterone antagonists.
Drugs to prevent or reverse Ventricular remodeling
Natriuretic peptides (atrial natriuretic peptide [ANP] and brain [b-type] natriuretic peptide [BNP]) are
hormones made by the heart muscle.
the atria in response to increased blood volume and ventricular wall stretching.
ANP is released from
from the ventricles in response to increased blood volume and ventricular wall stretching.
BNP is released
have beneficial renal, cardiovascular, and hormonal effects.
natriuretic peptides
-Renal effects include: (1) increased glomerular filtration rate and diuresis and (2) excretion of sodium (natriuresis). -Cardiovascular effects include vasodilation and decreased BP. -Hormonal effects include (1) inhibition of aldosterone and renin secretion and (2) interference with ADH release.
combined effects of ANP and BNP help to counter the adverse effects of the SNS and RAAS
mortality in HF.
. High serum BNP corresponds proportionately with fluid retention and is a predictor of
are counterregulatory substances released from the vascular endothelium in response to the compensatory mechanisms activated in HF.
Nitric oxide (NO) and prostaglandin (compensating)
to relax the arterial smooth muscle, resulting in vasodilation and decreased afterload.10
NO and prostaglandin work
occurs when compensatory mechanisms succeed in maintaining an adequate CO that is needed for tissue perfusion.
Compensated HF
occurs when these mechanisms can no longer maintain adequate CO and inadequate tissue perfusion results.
Decompensated HF
that emphasizes the evolution and progression of HF as well as treatment strategies
American College of Cardiology Foundation and the American Heart Association (ACCF/AHA) more recently developed a staging system (A–D)
people at risk for developing HF who do not currently
have heart disease (stage A)
is an increase (usually sudden) in symptoms of HF with a decrease in functional status, often requiring rapid escalation of therapy and hospital admission
Acute decompensated heart failure (ADHF)
pulmonary congestion and volume overload.
presentation of ADHF typically includes symptoms and signs related to
through the kidneys that results in sodium and fluid accumulation
Neurohormonal activation in Acute decompensated HF leads to impaired regulation of sodium excretion
If pulmonary venous pressure continues to increase, the increase in intravascular pressure causes more fluid to move into the interstitial space than the lymphatics can remove resulting in interstitial edema
- Tachypnea develops, and short of breath
- alveoli edema
- respiratory acidosis cuz no O2
Acute decompensated heart failure (ADHF)
This is an acute, life-threatening situation, in which the lung alveoli become filled with serosanguineous (blood & liquid part of serum) fluid
ADHF can manifest as pulmonary edema.
pulmonary edema include acute manifestations of left HF, such as dyspnea, orthopnea, and paroxysmal nocturnal dyspnea. JVD is often present and is the most sensitive and specific sign for elevated LV filling pressures. Coughing, crackles and wheezes, alveolar edema, s3,s4 heard, BP can be high or low depends on severity.
ADHF (cause Left HF)
Hypotension indicates severe LV systolic dysfunction and the chance of cardiogenic shock
low bp in ADHF (cause left HF) indication