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1. Anatomy
2. Microbiology
3. Physiology
4. Pathology
4.1 General pathology
4.2 Central and peripheral nervous system
4.3 Cardiovascular system
4.3.1 Endocarditis, myocarditis and pericarditis
4.3.2 Cardiomyopathies
4.3.3 Hypertrophy of the heart
4.3.4 Atherosclerosis and arteriosclerosis
4.3.5 Ischemic heart disease (IHD)
4.3.6 Diagnosis of AMI/ ACS
4.3.7 Heart failure
4.3.8 Valvular heart disease
4.3.9 Arrhythmias
4.3.10 Vascular disorders
4.3.11 Common types of emboli
4.3.12 Vasculitis
4.3.13 Diseases of the veins
4.3.14 Additional information
4.4 Respiratory system
4.5 Hematology and oncology
4.6 Gastrointestinal pathology
4.7 Renal, endocrine and reproductive system
4.8 Musculoskeletal system
5. Pharmacology
6. Immunology
7. Biochemistry
8. Cell and molecular biology
9. Biostatistics and epidemiology
10. Genetics
11. Behavioral science
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4.3.7 Heart failure
Achievable USMLE/1
4. Pathology
4.3. Cardiovascular system

Heart failure

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Heart failure or cardiac failure is the inability of the heart to maintain an adequate cardiac output that maintains the metabolic needs of the body. It may be systolic, diastolic, left ventricular, right ventricular or bi-ventricular, acute or chronic. Failure of normal pumping ability of the ventricle is called systolic failure and presents with reduced ejection fraction (<40%). On the other hand, impaired ventricular relaxation or filling due to increase in wall stiffness causes diastolic dysfunction. Ejection fraction is preserved in diastolic dysfunction, although it will present with increase in filling pressures. Congestive heart failure is heart failure with pulmonary and/or systemic congestion and can be seen in LHF/RHF or biventricular failure.

Cardiac failure
Cardiac failure

Common causes of heart failure

  • CAD or IHD
  • DM
  • Hypertension
  • Cardiomyopathy
  • Myocarditis
  • Congenital heart disease
  • Valvular heart disease
  • Arrhythmias esp. tachyarrhythmias
  • Alcohol abuse, Beriberi
  • HIV/AIDS
  • Hypervitaminosis E
  • Radiation or chemotherapy
  • Thyroid disorders
  • Severe anemia
  • Cocaine and drug abuse
  • AV shunts
  • Massive pulmonary embolism
  • Cardiac tamponade and constrictive pericarditis

I) Left-sided heart failure (LHF): Systolic dysfunction of the left ventricle from impaired ventricular contractility can be due to AMI, CAD, volume overload from MR or AR,dilated cardiomyopathy etc. Systolic dysfunction can also result from increased afterload due to systemic hypertension or aortic stenosis. Diastolic dysfunction of LV can be due to impaired relaxation due to LVH, HOCM or restrictive cardiomyopathy, CAD or it may result from impaired ventricular filling from MS, cardiac tamponade or constrictive pericarditis. LHF causes accumulation of fluid buildup in the lungs causing pulmonary edema and systemic hypoperfusion.

II) Right-sided heart failure (RHF): Systolic dysfunction of RV may result from increased afterload from pulmonary HT, COPD, PE, ILD, ARDS or pulmonic stenosis. Impaired contractility of RV can result from AMI, volume overload from TR or PR and dilated cardiomyopathy. Diastolic dysfunction of RV can result from causes such as tricuspid stenosis plus pathologies similar to those causing diastolic dysfunction of LV like tamponade etc. The most common cause of RV failure is LV failure. RHF causes fluid buildup in the systemic and portal venous system presenting as peripheral pitting edema and hepatic congestion.

Comparison between LHF and RHF

LHF
  • Dyspnea, orthopnea, paroxysmal nocturnal dyspnea
  • Cough with frothy sputum
  • Decreased urine output
  • Pulmonary crackles, rhonchi
  • In severe cases, loud P2, systolic murmur from MR, pulsus alternans
  • Hemosiderin containing alveolar macrophages or “heart failure” cells
  • CxR shows Kerley’s B lines on from septal pulmonary edema; perihilar congestion and alveolar infiltrates
RHF
  • Peripheral pitting edema, ascitis
  • Hepatosplenomegaly
  • Raised JVP
  • In severe cases, Kussmaul sign, TR murmur and right ventricular heave
  • Hepatojugular reflex will be positive
  • Central cyanosis more common
Raised JVP
Raised JVP

S3 and S4 can be auscultated. S3 is due to abnormal filling of blood into an already volume overloaded ventricle. S4 is due to forceful atrial contraction against a stiff ventricle and is seen in diastolic dysfunction such as LVH or RVH.

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