Heart Failure Flashcards
What is it heart failure
. Heart ailure is present when the heart
is unable to pump blood orward at a su f cient rate to meet the metabolic demands o the body or is able to do so only in cardiac filling pressures are abnormally high.
This concept o a terload is also relevant to the intact heart:
the pressure generated by
the ventricle and the size o the chamber at the end o each contraction depend on the load
against which the ventricle contracts but are independent o the stretch on the myocardial
f bers be ore contraction
In a healthy person, cardiac output is matched to
the body’s total metabolic need.
Cardiac output (CO) is equal to the product o stroke volume (SV, the volume o blood ejected with
each contraction) and the heart rate (HR):
CO = SV x HR
The three major determinants o stroke volume are
preload, a terload, and myocardial
contractility,
ventricular unction curve
Frank–Starling curve,
the more a normal ventricle is distended (i.e., f lled with blood) during diastole, the greater the volume that is ejected during the next systolic contraction.
Preload
the amount of myocardial stretch at the end of diastole, just before contraction
The ventricular wall tension at the end o diastole. In clinical terms, it is the stretch on the ventricular bers just be ore contraction, often approximated by the end-diastolic volume or end-diastolic pressure.
Measurements that correlate with myocardial stretch, and that are often
used to indicate the preload on the horizontal axis, are the
Are the ventricular end diastolic volume (EDV) or
or end-diastolic pressure (EDP)
Conditions that decrease intravascular volume,
and thereby reduce ventricular preload (e.g., dehydration or severe hemorrhage) result in a smaller
EDV and hence a reduced stroke volume during contraction
an increased volume within the le t ventricle during diastole (e.g., a large intravenous uid
in usion) results in a
greater-than-normal stroke volume.
Afterload
The ventricular wall tension during contraction; the orce that must be overcome or the ventricle to eject its contents. Often approximated by
the systolic ventricular (or arterial) pressure
Contractility (inotropic state)
Property o heart muscle that accounts or changes in the strength of contraction, independent o the preload and a terload. Reflects chemical or hormonal inf uences (e.g., catecholamines) on the orce of
contraction
Stroke volume (SV)
Volume o blood ejected rom the ventricle during systole SV = End-diastolic volume – end-systolic volume
Ejection raction (EF)
The raction o end-diastolic volume ejected rom the ventricle during
each systolic contraction (normal range = 55%–75%)
EF = Stroke volume ÷ end-diastolic volume
Cardiac output (CO)
Volume o blood ejected rom the ventricle per minute
CO = SV × Heart rate
Compliance
Intrinsic property o a chamber that describes its pressure–volume
relationship during illing. Re lects the ease or di iculty with
which the chamber can be illed. Compliance = ∆ volume ÷ ∆ pressure
isovolumetric contraction
When the pressure in the left ventricle (LV) exceeds that o the left atrium (point b), the
mitral valve is forced to close. As the pressure continues to increase, the ventricular volume
does not immediately change, because the aortic valve has not yet opened; therefore, this
phase is called
isovolumetric relaxation
As the ventricle continues to relax, its pressure declines while its volume remains constant
because the mitral valve has not yet opened
Ventricular stroke volume is a function of
preload, a terload, and contractility. SV rises
when there is an increase in preload, a decrease in a terload, or augmented contractility
Ventricular EDV (or EDP) is used as a representation of preload
he EDV is in uenced by the chamber’s compliance.
Ventricular ESV depends on the
afterload and contractility but not on the preload
etiologies of Heart failure
1) impair ventricular contractility,
(2) increase a terload,
or (3) impair ventricular relaxation and filling
systolic dysfunction
Heart ailure that results rom
an abnormality o ventricular emptying (due to impaired contractility or greatly excessive afterload)
diastolic dysfunction
is termed systolic dysfunction, whereas heart ailure caused by abnormalities of diastolic relaxation or ventricular filling is called
Impaired Contractility
1. Coronary artery disease • Myocardial infarction • Transient myocardial ischemia 2. Chronic volume overload • Mitral regurgitation • Aortic regurgitation 3. Dilated cardiomyopathies
Leading to
Reduced Ejection Fraction
(Systolic Dysfunction)
Heart Failure
Impaired Diastolic Filling
- Left ventricular hypertrophy
- Restrictive cardiomyopathy
- Myocardial fibrosis
- Transient myocardial ischemia
- Pericardial constriction or
tamponade
Leading to
Preserved ejection fraction
(Diastolic Dysfunction)
Heart Failure
⇈Afterload
Chronic Pressure Overloada
- Advanced aortic stenosis
- Uncontrolled severe hypertension
Leading to
Reduced Ejection Fraction
(Systolic Dysfunction)
Heart Failure
Heart Failure with reduced ejection fraction
In states of systolic dysfunction, the affected ventricle has a diminished capacity to eject
blood because of impaired myocardial contractility or pressure overload (i.e., excessive afterload). Loss ofcontractility may result from destruction of myocytes, abnormal myocyte function, or fibrosis. Pressure overload impairs ventricular ejection by significantly increasing resistance to flow
Heart Failure with Preserved EF
frequently demonstrate abnormalities of
ventricular diastolic function: impaired early diastolic relaxation (an active, energy-dependent
process), increased sti ness o the ventricular wall (a passive property), or both.
Acute myocardial ischemia is an example of a condition that transiently inhibits energy delivery and
diastolic relaxation.
Conversely, left ventricular hypertrophy, fibrosis, or restrictive cardiomyopathy causes the LV walls to become chronically stiffened.
Certain pericardial
diseases (cardiac tamponade and pericardial constriction, ) present an external force that limits ventricular filling and represent potentially reversible forms of diastolic dysfunction. The effect of impaired diastolic function is reflected in the pressure–volume
loop : in diastole, filling of the ventricle occurs at higher-than-normal pressures because the lower part o the loop is shifted upward as a result of reduced chamber compliance.
Patients with diastolic dysfunction often manifest signs of vascular congestion because the elevated diastolic pressure is transmitted retrograde to the pulmonary and systemic veins
Examples of Conditions That Cause Right-Sided Heart Failure
Cardiac causes
Left-sided heart failure
Pulmonic valve stenosis
Right ventricular infarction
Pulmonary parenchymal diseases
Chronic obstructive pulmonary disease
Interstitial lung disease (e.g., sarcoidosis)
Chronic lung infection or bronchiectasis
Pulmonary vascular diseases
Pulmonary embolism
Pulmonary arteriolar hypertension
Common Symptoms and Physical Findings in Heart Failure
Symptoms + Physical findings
Left sided
Left sided Dyspnea Diaphoresis (sweating) Orthopnea Tachycardia, tachypnea Paroxysmal nocturnal dyspnea Pulmonary rales Fatigue Loud P2 S3 gallop (in systolic dysfunction) S4 gallop (in diastolic dysfunction)
Common Symptoms and Physical Findings in Heart Failure
Physical findings + Symptoms
Right sided Peripheral edema Jugular venous distention Right upper quadrant discomfort (because of hepatic enlargement) Hepatomegaly Peripheral edema
