Heart Failure

 

Definition: 

 

A clinical syndrome that develops when the heart cannot maintain an adequate cardiac output, or can do so only at the expense of an elevated filling pressure.

Epidemiology:

  • The prevalence of heart failure in the United States is more than 5.8 million and more than 23 million cases worldwide.

  • The main cause of heart failure is Ischemic Heart Diseases.


Classification and types:
Acute vs. chronic:

  1. Acute HF:

  • Can be reversible.

  • Usually progresses into chronic HF.

      2.    Chronic HF:

  • More common.

  • Compensatory changes.

Left sided vs. Right sided:

  1. Left sided HF:

  • Most common causes: ischemic heart disease, HTN, mitral or aortic valve disease, or primary disease of the myocardium

     2.    Right sided HF:

  • Most common cause in general is left sided HF.

  • Another important cause is severe pulmonary HTN (Cor Pulmonale.)

Systolic vs. Diastolic:

  1. Systolic HF (decreased ejection fraction EF):

  • Ventricle contracts poorly and empties inadequately, leading initially to increased diastolic volume and pressure and decreased EF.

     2.     Diastolic HF (preserved EF):

  • Ventricular filling is impaired, resulting in reduced ventricular end-diastolic volume, increased end-diastolic pressure, or both. 

Risk factors:

  • Age >65 Y/O.

  • Gender (M>F).

  • Race (more common in African Americans).

  • Obesity & increased weight.

 

Pathophysiology:
Neuro-humoral adaptation:

  • Sympathetic nervous system activation:

    1. Increase the release and decrease uptake of norepinephrine.

    2. Catecholamines help in maintaining the cardiac output during exercise especially in early HF.

  • Renin-angiotensin- aldosterone system:

    1. Activation of the RAAS is dependent on low cardiac output, and low renal perfusion.

    2. RAAS activation  → fluid retention → increases the ventricular preload.

    3. Angiotensin II actions:

                           A. Increase the Na+ reabsorption in the proximal tubules (due to aldosterone).
                           B. Systemic and renal vasoconstriction.
                           C. Acts directly on the myocytes to promote the pathological remodeling in HF.
Systolic dysfunction with decreased EF:

  • The ventricle contracts poorly and empties inadequately, leading initially to increased diastolic volume and pressure and decreased EF.

  • Predominant systolic dysfunction is common in HF due to MI, myocarditis, and dilated cardiomyopathy. 

Diastolic dysfunction with preserved EF:

  • Ventricular filling is impaired, resulting in reduced ventricular end-diastolic volume, increased end-diastolic pressure, or both.

  • Contractility and hence EF remain normal; EF may even increase as the poorly filled LV empties more completely to maintain CO.

  • Elevated left atrial pressures can cause pulmonary hypertension and pulmonary congestion.

  • Diastolic dysfunction usually results from impaired ventricular relaxation (an active process), increased ventricular stiffness, valvular disease, Acute MI, or constrictive pericarditis.

  • Diastolic dysfunction is common among the elderly due to increased resistance to filling.

Left ventricular failure (LVF):

  • Cardiac output deceases and pulmonary venous pressure increase.

  • Marked pulmonary edema, which alters the V/Q relationship leading to significant dyspnea.

  • In severe LVF, pleural effusion might develop exacerbating the dyspnea.

Right ventricular failure: 

  • Back flow of the blood leading to increase of the systemic venous pressure.

  • Leading to fluid extravasation and edema primarily in ankles & feet in ambulatory patients, sacral area in bedridden patients, and abdominal viscera (hepatomegaly and ascites).

  • Moderate hepatic dysfunction with increased of total bilirubin.

 

Causes:
Main causes: 

  • IHD 40%.

  • Dilated cardiomyopathy 34%.

  • HTN 20%. 

Others:

  • Other causes of cardiomyopathy.

  • Valvular heart disease (mitral and aortic).

  • Congenital heart disease.

  • Chaga’s disease (myocarditis).

  • Pericardial diseases. 

Symptoms & Signs:
Symptoms: they might overlap.

Study guide:

Signs

  • Tachycardia

  • Hypotension

  • Raised JVP

  • Displaced apex beat (cardiomegaly)

  • S3+S4 heart sounds

  • Bilateral basal crackles (pulmonary edema)

  • Stony dull percussion on the lungs (pleural effusion)

  • Hepatomegaly

  • Positive shifting dullness or fluid thrill maneuvers (ascites)

  • Peripheral ankle and feet edema.

  • Sacral edema.

Investigations:

  • Blood tests:

  1. High BNP.

  2. Recommended blood tests include CBC, creatinine, BUN, electrolytes (including Mg+ and
    Ca+2), glucose, albumin, and liver function tests.

  3. Thyroid function tests are recommended for patients with atrial fibrillation and for
    selected, especially elderly, patients.

  • CXR:

  1. Cardiomegaly (cardiothoracic ratio>0.5).

  2. Pulmonary congestion.

  3. Kerley B lines.

  4. Fluid in pulmonary fissures.

  5. Pleural effusion.

  • ECG:

  1. May show left ventricular hypertrophy, LBBB, previous MI, or tachyarrhythmia.
     

  • Echocardiography: 

  1. To evaluate the cardiac dimensions, systolic and diastolic functions, regional wall motion
    abnormalities, valvular heart disease, and cardiomyopathies. 

High BNP is a poor prognostic factor. 

High BNP is a poor prognostic factor. 

Any patient with CHF must undergo echocardiography to evaluate EF. 

NYHA Classification of HF:

 Managment:

  • General lifestyle advice: 

  1. Smoking cessation, obesity control, and increasing physical activity.

  • Surgical & procedural treatment:

  1. Heart transplantation.

  2. Ventricular remodeling.

  3. Valvular interventions.

  • Medications: 

Complications:

Mortality benefit in systolic HF:

  • ACEi or ARBs

  • Betablockers

  • Spironolactoneoreplerenone

  • Hydralazine or nitrates

  • Implantabledefibrillator  

References:

  1. Hall J, Guyton A. Guyton and Hall textbook of medical physiology.

  2. Kumar P, Clark M. Kumar & Clark's clinical medicine.

  3. Walker B, Colledge N, Ralston S, Penman I. Davidson's principles and practice of medicine.

  4. Merck Manuals Professional Edition. Heart Failure - Cardiovascular Disorders [Internet]. 2015 [cited 21 December 2015].

    Available from: http://www.merckmanuals.com/professional/cardiovascular-disorders/heart-failure/heart-failure

  5. Lilly L. Pathophysiology of heart disease. Baltimore, MD: Wolters Kluwer/Lippincott Williams & Wilkins; 2011.

  6. Rang H, Dale M. Rang and Dale's pharmacology. Edinburgh: Elsevier/Churchill Livingstone; 2012.

  7. Andrew P. Renin-Angiotensin-Aldosterone Activation in Heart Failure, Aldosterone Escape. Chest. 2002;122(2):755-755.

  8. Le T, Bhushan V, Singh Bagga H. First aid for the USMLE step 2 CK. New York: McGraw-Hill Medical; 2010.

  9. Le T, Bhushan V, Sochat M, Sylvester P, Mehlman M, Kallianos K. First aid for the® USMLE.

  10. Fischer C. Master the boards.

  11. Wikipedia. Edema [Internet]. 2015 [cited 21 December 2015]. Available from: https://en.wikipedia.org/wiki/Edema (Figure1).

  12. Wikidoc.org. Heart failure resident survival guide - wikidoc [Internet]. 2015 [cited 21 December 2015]. Available from:

    http://www.wikidoc.org/index.php/Heart_failure_resident_survival_guide (Figure2). 

 

 

Written By:    Lama Al-Luhidan      
                                                                    
Reviewed by:   Roaa Amer


Format Editor: Salman Alahmed

                             Bayan Alzomaili