Cardiac Muscle Dysfunction and Heart Failure

Cardiac Muscle Dysfunction (CMD) and Heart Failure

Impact of Congestive Heart Failure (CHF)

  • Estimated 5.7 million+ Americans suffer from CHF.
  • Approximately 670,000 new cases occur yearly.
  • 1.1 million hospitalizations each year are due to CHF.
  • Lifetime risk of developing heart failure above age 40 is 1 in 5.
  • Annual rate of developing heart failure over age 85 is 65%.
  • Individuals with heart and lung disease are likely to develop CHF, often manifested as pulmonary congestion or edema.
  • CHF develops secondary to abnormalities of cardiac structure or function.

Cardiac Muscle Dysfunction (CMD)

  • CMD is a common finding in patients with heart and lung disease.
  • It's the most common cause of congestive heart failure.
  • Develops as a result of underlying abnormalities of cardiac structure or function.
  • Patients with CMD may be asymptomatic initially but are at risk of heart failure.
  • As CMD progresses, the heart fails to meet the demands of the system, leading to heart failure.
  • CMD impacts the heart muscle's structure and function, potentially leading to heart failure.

Introduction to Heart Failure

  • Heart failure is a chronic, progressive condition.
  • The heart loses its ability to effectively pump blood to extremities, organs, and skin.
  • Supply does not equal demand due to a reduction in cardiac output.
  • When the body's blood and oxygen requirements are unmet, clinical syndromes with various signs and symptoms arise.
  • Pathophysiological compensatory responses to CMD negatively impact multiple organ systems (lungs, kidneys, liver, skeletal muscle).

Pathophysiology of Heart Failure

  • Most commonly caused by CMD or issues with the heart muscle structure and function.
  • Can involve altered systolic and/or diastolic activity of the myocardium.
  • Typically develops due to underlying abnormalities.

Subtypes of Heart Failure

  • Categorized from structural and functional perspectives.

Structural Types

  • Left-sided heart failure
  • Right-sided heart failure
  • Both (biventricular heart failure)
  • Cannot be determined just from our own assessment. Usually done with medical testing.

Functional Types

  • Diastolic heart failure (heart failure with preserved ejection fraction - HFPEF)
  • Systolic heart failure (heart failure with reduced ejection fraction - HFREF)

Fluid Accumulation

  • Left-sided heart failure: fluid accumulates in the lungs.
  • Right-sided heart failure: fluid accumulates in the rest of the body.

Heart Failure with Reduced Ejection Fraction (HFREF)

  • Secondary to low cardiac output at rest or during exertion.
  • Resting ejection fraction is less than 40% (sometimes seen as 35%).

Heart Failure with Preserved Ejection Fraction (HFPEF)

  • Impaired relaxation of the left ventricle and passive left ventricle compliance, leading to stiffness and increased diastolic pressures.
  • Ejection fraction is greater than 50%.

Systolic vs. Diastolic Heart Failure

  • Systolic Heart Failure: Impaired contraction of the left ventricle during systole, leading to decreased stroke volume and ejection fraction.
  • Diastolic Heart Failure: Impaired filling ability of the left ventricle, affecting its ability to accept blood during diastole. Preserved ejection fraction.

Left-Sided Heart Failure

  • Occurs due to a left ventricle insult.
  • Results in reduced cardiac output and accumulation of fluid within the left atrium.
  • Leads to pulmonary congestion or pulmonary edema, causing dyspnea and coughing.
  • Renal-mediated fluid retention occurs due to reduced blood flow to the kidneys, leading to overall fluid retention.

Right-Sided Heart Failure

  • Occurs due to a right ventricle insult.
  • Commonly caused by conditions that elevate pressure in the pulmonary arterial system (pulmonary hypertension).
  • Reduces cardiac output, causes venous congestion, jugular vein distension, peripheral edema, ascites, and pleural effusion.

Biventricular Heart Failure

  • Both ventricles fail.
  • Left-sided heart failure backs up into the left atrium, causing pulmonary vascular congestion.
  • Pulmonary vascular congestion increases pulmonary blood pressure, impacting the right ventricle.
  • The right ventricle becomes overloaded, backing up into systemic venous congestion, which affects the left side of the heart.
  • Results in pulmonary and peripheral signs and symptoms of fluid overload.

Functional Heart Failure (Reiteration)

  • Heart failure with preserved ejection fraction (HFPEF) = Diastolic heart failure.
  • Heart failure with reduced ejection fraction (HFREF) = Systolic heart failure.

HFPEF in Detail

  • Impaired filling ability of the left ventricle.
  • Reduced end-diastolic volume.
  • Results in reduced stroke volume and cardiac output, even if ejection fraction is over 50%.
  • Represents at least 50% of the heart failure population.

HFREF in Detail

  • Muscle contraction issue, inefficient expulsion of blood.
  • Results in reduced stroke volume.

Visual Representation

  • Systolic Dysfunction: Thinner walls, dilated ventricles, unable to contract fully, reduced ejection fraction.
  • Diastolic Dysfunction: Thickened heart muscle (cardiac hypertrophy), reduced chamber size, less blood filling, reduced stroke volume.

ACC/AHA Stages of Heart Failure

  • Stage A: At risk for heart failure but no current/previous symptoms.
    • Risk factors: hypertension, cardiovascular disease, atherosclerosis, diabetes, obesity, exposure to cardiotoxic agents, genetic variant for cardiomyopathy, family history.
  • Stage B: Pre-heart failure, patients with evidence of structural heart disease or increased filling pressure but no current/previous symptoms.
    • Risk factors: Increased BNP levels, persistent elevated cardiac troponin in the absence of competing diagnoses
  • Stage C: Symptomatic heart failure, patients with current/previous symptoms.
  • Stage D: Advanced heart failure, symptoms interfere with daily life and recurrent hospitalization despite attempts to optimize GDMT (Guideline-Directed Medical Therapy).

New York Heart Association (NYHA) Heart Failure Classification

  • Class I: No limitations, normal physical activity does not cause fatigue, palpitation, or shortness of breath.
  • Class II: Slight limitation of physical activity, comfortable at rest, ordinary physical activity results in fatigue, palpitations, shortness of breath.
  • Class III: Marked limitation of physical activity, comfortable at rest, less than ordinary activity causes fatigue.
  • Class IV: Severe limitations, symptoms at rest.

Causes of Heart Failure

  • Ischemic heart disease and previous MI (weakens heart muscle).
  • Hypertension (chronic demand on the heart muscle causes thickening).
  • Valve heart disease.
  • Genetic component/family history.
  • Arrhythmias.
  • Autoimmune causes.
  • Thyroid and other endocrine diseases.
  • Cardiotoxicity (cancer, substance abuse).
  • Tachycardia & Right ventricular pacing.
  • Peripartum cardiomyopathy.
  • Anything that systemically affects the heart's ability to function.

Cardiomyopathy

  • Disease of the heart muscle, differentiated based on function.
    • Dilated
    • Hypertrophic
    • Restrictive

Dilated Cardiomyopathy

  • Cardiac mass is increased, enlarged heart, all chambers dilated.
  • Systolic dysfunction (ineffective pumping).
  • Causes: idiopathic, alcohol, inflammation, pregnancy, metabolic disorder, AIDS infection.

Hypertrophic Cardiomyopathy

  • Increased cardiac mass with thickened walls.
  • Diastolic dysfunction (impaired filling).
  • Risk of sudden cardiac death.
  • Rapid ventricular emptying and normal ejection fraction.
  • Causes: Hereditary, abnormal sympathetic nervous system stimulation, subendocardial ischemia, abnormal calcium ion dynamics.

Restrictive Cardiomyopathy

  • Least common type, restricts the heart from stretching, decreased compliance.
  • Causes: cardiac amyloidosis, sarcoidosis, hemochromatosis.
  • Autoimmune related conditions.

Pathophysiology of Heart Failure (Reiteration)

  • Decreased cardiac output.
  • Blood supply doesn't meet demand.
  • The body compensates to maintain cardiac output.
  • Results in pulmonary edema (increased pulmonary capillary pressure).
  • Left ventricle failure is the most common cause.
  • Renal function is affected due to fluid/blood involvement.

Clinical Manifestations of Congestive Heart Failure

  • Dyspnea at rest (most common).
  • Poor gas exchange.
  • Paroxysmal nocturnal dyspnea (difficulty breathing when sleeping).
  • Orthopnea (dyspnea in a recumbent position, requiring two to three pillows).
  • Tachypnea (rapid respiratory rate).
  • Resting dyspnea, dyspnea with exertion, occasional dyspnea with positional changes.
  • Crackles and rales (fluid within the alveoli).

Abnormal Heart Sounds

  • S3 (hallmark of heart failure): noncompliant left ventricle makes contact with the chest wall in early diastole.
  • S4: vibration of ventricle walls during rapid influx of blood during atrial contraction (exaggerated atrial kick) in late diastole.

Peripheral Edema

  • Accompanies right-sided heart failure.
  • Fluid accumulates bilaterally in the periphery.
  • Accumulates in the legs.

Jugular Vein Distension

  • Results from fluid overload.
  • Measure with the bed at 45 degrees.

Weight Gain

  • Increase of 2-3 pounds per day or 5 pounds over three days suggests decompensated cortisol.

Other Symptoms

  • Chemoreceptors detect fluid volume and decreased oxygen levels, leading to faster breathing.
  • Increased resting heart rate.
  • The body is trying to compensate and deliver fluid and O2 to peripheral tissues.
  • Fluid retention.

Decreased Exercise Tolerance

  • Onset of anaerobic metabolism due to abnormalities in skeletal muscle.
  • Difficulty in delivering oxygen to muscles.
  • Fiber atrophy, loss of oxidative type one fibers, increase in glycolytic type two fibers.

Assessment

  • Monitor symptoms, heart rate, oxygen saturation, blood pressure, heart rhythm, respiratory rate at specific workloads.
  • Treadmill, cycle, hallway walking, strength training, six-minute walk test.

Radiologic Findings (Chest X-Ray)

  • Fluid in the lungs.
  • Cardiac silhouette size and shape (enlarged heart should be less than half the width of the rib cage).
  • Pleural effusion, atelectasis, or lung collapse.

Medical Management

  • Dietary changes, nutritional support, pharmacologic treatment.
    • ACE inhibitors
    • Beta blockers
    • Diuretics
    • Positive inotrope medication
      Blood pressure reduction with ACE inhibitors and beta blockers for vasodilation.
  • Positive ionotrope medication. Remember contractility.So trying to get that heart to contract harder if it's a systolic issue

Physical Therapy Management

  • Shortness of breath is the limiting factor.
  • Do not begin aerobic training until heart failure is compensated/stable (vital signs stable).
  • Mobility starts after stabilization.
  • Ambulation is the most effective and functional mode of exercise.
  • Small bouts, frequent rest breaks (intermittent walking).
  • Assess intensity by levels of dyspnea or the RPE scale.
  • Six-minute walk test: assess functional status, exercise tolerance, oxygen consumption; better test results = better outcomes.