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Giới thiệu
Heart failure is a clinical syndrome
due to a structural or functional cardiac disorder that impairs the ability of
the ventricle to fill with or eject blood in order to deliver oxygen at a rate
commensurate with the requirements of the metabolizing tissues in spite of
normal filling pressures or only at the expense of elevated filling pressures. It
is corroborated by the objective evidence of cardiogenic, pulmonary, or systemic
congestion or elevated levels of natriuretic peptides.
The symptoms of heart failure are
caused by ventricular dysfunction secondary to abnormalities of the myocardium,
pericardium, endocardium, valves, or heart rhythm or conduction.
Dịch tễ học
The incidence of heart failure increases with age
with a higher increase in females as compared to males. The prevalence rate in
adults is 1-2% or approximately 64 million, with prevalence increasing with
age. The prevalence rate in patients <55 years old is approximately 1% and
>10% in patients ≥70 years old.
The prevalence rates are higher in North Africa,
Central Europe, and the Middle East, and lowest in Eastern Europe and Southeast
Asia. The lifetime risk of developing heart failure is approximately 20% in
individuals >40 years of age. Among the phenotypes, heart failure with
reduced ejection fraction (HFrEF) remains to be the most common overall. Heart
failure is also expected to increase largely due to the collective effects of
increasing risk factors and comorbidities.
According to the China Hypertension Survey in
2012-2015, the estimated prevalence of heart failure was 1.3% affecting
approximately 14 million Chinese aged ≥35 years old. The country’s crude
in-hospital mortality was 4.1%. In Taiwan, the prevalence of heart failure was
estimated at 6% with approximately 2.2% or 40,000 hospitalizations per
year. In Hong Kong, the prevalence rate
was 2-3%. The Korean Society of Heart Failure reported that there was an
increasing prevalence of the disease at 0.8% in 2002, 1.5% in 2013, and 2.2% in
2018. The age-adjusted incidence decreased by 20% from 693 in 2004 to 554 per
100,000 population in 2018. The overall mortality rate likewise increased from
39 in 2004 to 245 per 100,000 population in 2018.
The overall prevalence of heart failure in the
Philippines was 1-2% and the disease is considered a common cause of
in-hospital mortality at 7-8%. In Thailand, the overall prevalence was reported
to be 0.4%, however, the hospitalization and in-patient mortality were
significantly high at 19% and 5-6%, respectively. The prevalence rate in
Indonesia was 5%. Recent studies have shown that South Asia has a
relatively increased risk of heart failure compared to other racial or
geographic areas with an estimated prevalence of 1.3-6.7%. In India, the
prevalence of heart failure was estimated to be 1.3-4.6 million as of 2014 with
an incidence of 0.5-1.7 per 1000 persons yearly. It is likewise a significant
contributor to mortality in the country.
Heart failure among Asians generally occurs at a
younger age relative to Western countries. Despite improvement in heart failure
management, the crude mortality among Asians remains high and was estimated to
be 9.6% among symptomatic patients.
Sinh lý bệnh
Heart failure results
from the impairment of cardiac contractile function (systolic dysfunction) and
cardiac filling impairment (diastolic dysfunction).
Cardiac injury
stimulates cellular, structural, and neurohumoral modulations influencing cell
function leading to activation of the sympathoadrenergic and
renin-angiotensin-aldosterone system (RAAS) and resulting to adaptive
mechanisms accompanied by volume overload, tachycardia, dyspnea, and further
deterioration of the cellular function.
Catecholamines increase
intracellular calcium thereby increasing contractility but increases myocardial
oxygen demand in the long run which can lead to life-threatening arrhythmias and
activation of signaling pathways of hypertrophy and cell death resulting to
further cardiac function deterioration. Permanent activation of the
neurohumoral system also affects cell expression and cell function (eg
stretch-induced force generation, frequency-induced force generation,
interstitial and structural cell-interaction).
Heart Failure with Preserved
Ejection Fraction (HFpEF)
HFpEF is characterized by impaired ventricular
relaxation and/or filling, increased ventricular stiffness, and elevated
filling pressure accompanied by pressure overload. Structural and cellular
changes (eg alteration of cardiomyocyte relaxation and inflammation,
cardiomyocyte hypertrophy, intercellular fibrosis) cause the inability of the left
ventricles to relax properly. The impairment of myocardial relaxation leads to
reduced rate and amount of early diastolic left ventricular filling resulting
to shifting of left ventricular filling to late diastole with atrial
contraction making an important contribution to left ventricular filling.
Alteration of left
ventricular diastolic function leads to decreased left ventricular chamber
distensibility and increased diastolic pressure at any given left ventricular
volume. It is associated with structural remodeling affecting the left
ventricle and left atrium, right ventricle, cardiomyocytes, and extracellular
matrix.
Heart Failure with Reduced
Ejection Fraction (HFrEF)
HFrEF occurs when there is a substantial acute or
chronic cardiomyocyte loss after myocardial infarction, genetic mutation,
myocarditis, or valvular disease with cell death due to overload that leads to
systolic dysfunction development. The major structural change is eccentric
remodeling accompanied by chamber dilatation and volume overload resulting to
forward failure. Volume overload results from permanent neurohumoral activation.
Systolic dysfunction triggers neurohumoral
activation and cardiac remodeling causing increased sympathetic activity which
restores cardiac output by increasing contractility and heart rate. The reduced
cardiac output also stimulates salt and water retention causing blood volume
expansion leading to increased end-diastolic pressure and volume.
Nguyên nhân
The following are the common causes of heart failure:
- Cardiac pathologies (eg coronary artery disease [CAD], cardiomyopathies, congenital heart disease, tachyarrhythmia, valvular heart disease)
- Hypertension
- Infiltrative cardiac disease (eg amyloid, hemochromatosis, sarcoid)
- Infections (eg rheumatic fever, sexually transmitted diseases, pneumonia)
- Endocrine disorders (eg diabetes, dyslipidemia, hypo- or hyperthyroidism, adrenal disorder, pheochromocytoma)
- Nutritional disorders (eg deficiency of thiamine, selenium, iron, calcium, phosphates and L-carnitine, obesity, cachexia)
- Toxins (eg alcohol, medications, trace elements, illicit drug use eg cocaine, cannabis, methamphetamine)
- Drugs (eg beta-blockers, calcium antagonists, antiarrhythmics, cardiotoxic chemotherapy agents, nonsteroidal anti-inflammatory drugs [NSAIDs], non-compliance to medications)
- Other diseases (eg inflammatory or immunological diseases, neuromuscular disease, malignancies, severe anemia, renal dysfunction, renal artery stenosis, and end-stage renal failure)
Phân loại
Types of Heart Failure
Heart Failure Based on Time-course
Acute heart failure (AHF) refers to
the first occurrence (new-onset or de novo) of heart failure that may result
from the deterioration of a previously stable heart failure.
Chronic heart failure (CHF) refers to a
chronic state where the patient’s signs and symptoms have been unchanged
(stable) for at least a month. The condition may decompensate suddenly or
slowly when stable chronic heart failure deteriorates leading to
hospitalization or outpatient intravenous diuretic therapy.
Congestive heart failure refers to acute
heart failure or chronic heart failure that has evidence of volume overload.
Transient heart failure refers to
symptomatic heart failure over a limited period, although long-term therapy may
be indicated. Transient heart failure may be recurrent or episodic.
Heart Failure Based on Left Ventricular
Ejection Fraction (LVEF)
Heart failure with preserved EF
(HFpEF) (diastolic heart failure) is defined as having preserved systolic
function and an ejection fraction that is defined as ≥50%. The condition is not
due to hypertrophic or infiltrative cardiomyopathy, high-ouput HF, or
pericardial or valvular disease.
Heart failure with reduced EF (HFrEF)
(systolic heart failure) is when the patient’s ejection fraction is defined as ≤40%.
Patients with an ejection fraction in
the 41-49% range represent a ‘grey area’ and it is termed heart failure with
mildly reduced ejection fraction (HFmrEF). Further criteria for the diagnosis
of heart failure with preserved and mildly reduced ejection fraction include the
presence of heart failure symptoms and/or signs, and elevated levels of
natriuretic peptides with at least one added criterion of either significant structural
heart disease or diastolic dysfunction.
Lastly, heart failure with improved EF
(HFimpEF) is characterized by a history of HFrEF or a baseline left ventricular
ejection fraction of ≤40%, whose EF has increased by ≥10% to >40%.
Chronic Heart Failure
Classification Based on Duration Since Last Admission
This classification helps optimize
guideline-directed medical therapy (GDMT) and are categorized according to the
following phases:
- C1 for Optimization Phase which includes patients who are recently diagnosed with heart failure and not on optimal guideline-directed medical therapy
- C2 for Remission Phase which includes patients with no hospitalization for heart failure for >6 months and the patient is with optimal medical therapy
- C3 for Vulnerable Phase which includes patients with recent hospitalization within 6 months but not within 30 days
- C4 for Transition Phase which includes patients with recent hospitalization within 30 days
Development Stages of Heart Failure
Stage A
Patients under Stage A are those at
high risk for heart failure but without structural or functional heart disease
or signs or symptoms of heart failure. Abnormal cardiac biomarkers are absent
in these patients, and this includes those with hypertension, atherosclerotic
cardiovascular disease, diabetes, obesity, or metabolic syndrome; the use of
cardiotoxins; and those with a family history or genetic variant for
cardiomyopathy.
Stage B
Patients under Stage B are those with
structural or functional heart disease but without prior or current signs or
symptoms of heart failure. This includes patients with previous myocardial
infarction (MI), reduced right ventricular function, left ventricular (LV) remodeling
including left ventricular hypertrophy (LVH), low ejection fraction, chamber
enlargement, wall motion abnormalities, or asymptomatic valvular disease. In
this stage, patients have elevated levels of natriuretic peptide or high-sensitive
cardiac troponin in the setting of cardiotoxin exposure. There is noted
increased filling pressures on invasive hemodynamic measurements or imaging.
Stage C
Patients under Stage C are those with
structural and/or functional heart disease with prior or current signs and/or
symptoms of heart failure. This includes patients with persistent heart failure
or heart failure in remission. These patients also present with shortness of
breath (SOB), fatigue, and decreased exercise tolerance.
Stage D
Patients under Stage D are those with
refractory, advanced, or end-stage heart failure. These patients have marked
signs and/or symptoms at rest despite guideline-directed medical therapy, refractory
or intolerant to guideline-directed medical therapy, or recurrent
hospitalization. Patients under this stage require specialized treatment
interventions.
Assessment of Functional Capacity
To assess the patient’s functional
capacity, the New York Heart Association (NYHA) Functional Classification in patients
with heart failure is utilized.
Class I
Patients under Class I
have no limitation of physical activity and ordinary physical activity does not
cause heart failure symptoms (eg palpitation, dyspnea, or fatigue).
Class II
Patients under Class II have a slight
limitation of physical activity. They are normally comfortable at rest, but
ordinary physical activity produces heart failure symptoms.
Class III
Patients under Class III have marked limitations
of physical activity, and they are comfortable at rest but less than ordinary activity
causes heart failure symptoms.
Class IV
Patients under Class IV are unable to
carry out any physical activity without discomfort. Heart failure symptoms are
present at rest and any physical activity will cause an increase in discomfort.