Insuficiência Cardíaca: Classificação, Diagnóstico e Fisiopatologia | Super Revisão de Cardiologia

Introduction to Cardiology and Insuficiência Cardíaca

Overview of Estratégia Méd

• Bruno Ferraz introduces himself as a cardiology professor at Estratégia Méd, emphasizing the focus on cardiology in today's super review.

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Insuficiência Cardíaca: Definition and Importance

Introduction to Insuficiência Cardíaca

• The session transitions into discussing insuficiência cardíaca (heart failure), focusing on its definition, classification, etiology, and diagnosis.

Key Concepts of Heart Function

• Insuficiência cardíaca is defined as a syndrome where heart function is compromised due to issues during diastole or systole.

• Effective filling (diastole) and ejection (systole) are crucial for heart function; any dysfunction in these processes can lead to heart failure.

Overview of Heart Failure

Epidemiology and Prevalence

• Heart failure affects 1-2% of the adult population, highlighting its significance as a syndrome.

• In individuals over 70 years old, prevalence increases to 10%, indicating a critical public health concern.

• It is the leading cause of hospitalization among all heart diseases, emphasizing its impact on healthcare systems.

Prognosis and Survival Rates

• The survival rate post-diagnosis is low; only 35% of patients are alive five years after diagnosis, which is worse than many cancers.

Etiology of Heart Failure

• The primary causes include ischemic heart disease and hypertension; in northern Brazil, Chagas disease is also significant.

Classification of Heart Failure

Symptom-Based Classification (NYHA)

• Class I: No symptoms with normal activities; ideal state for patients.

• Class II: Mild fatigue or dyspnea during ordinary activities.

• Class III: Significant fatigue or dyspnea with minimal exertion.

• Class IV: Symptoms present even at rest; unable to perform any activity without discomfort.

Fractional Ejection Classification

• New guidelines have introduced a classification based on ejection fraction:

• Reduced ejection fraction (<40%) and preserved ejection fraction (>50%).

• A new category for mildly reduced ejection fraction (40%-49%) was established in recent guidelines.

Staging Classification

• Stage A: At risk but no structural heart disease (e.g., smokers).

• Stage B: Structural heart damage has occurred (e.g., previous myocardial infarction).

• Stage C: Patient exhibits symptoms of heart failure.

• Stage D: Advanced heart failure requiring consideration for transplant options.

Etiologies and Pathophysiology

Main Causes of Heart Failure

• Ischemic heart disease leads to systolic dysfunction due to loss of contraction ability following myocardial infarction.

• Hypertensive cardiomyopathy primarily causes diastolic dysfunction by affecting the filling phase due to hypertrophy.

Right-Sided Heart Failure

• Conditions like pulmonary embolism can lead to right-sided heart failure by causing overload specifically in the right chambers.

High Output Heart Failure

• Rarely seen in practice but includes conditions such as hyperthyroidism and sepsis that increase cardiac output demands significantly.

Understanding Pathophysiology

Frank-Starling Mechanism

• Understanding this mechanism is crucial as it relates directly to treatment responses in heart failure management.

Understanding Cardiac Function and Heart Failure

The Frank-Starling Mechanism

• The heart is likened to a large spring or trampoline, where the Frank-Starling mechanism indicates that greater stretching of myocardial fibers leads to increased injection power.

• In hypovolemic patients (point A), minimal fiber stretch results in low ejection; thus, cardiac output decreases due to reduced blood volume.

• Normovolemic patients (point B) experience optimal fiber stretch and ejection, while hypervolemic patients face excessive stretch leading to decreased ejection capacity.

• Understanding this mechanism is crucial for managing hypervolemic patients by removing excess fluid from the body.

Hormonal Responses in Heart Failure

• Reduced cardiac output triggers renal hypoperfusion, activating the renin-angiotensin-aldosterone system (RAAS), which aims to retain sodium and water, ultimately causing hypervolemia and vasoconstriction.

• Baroreceptors detect low blood pressure due to decreased cardiac output, stimulating sympathetic nervous system activity that releases catecholamines to enhance heart contractility and rate.

• Chronic activation of these pathways can lead to apoptosis of myocardial cells, resulting in irreversible damage and heart function decline.

Treatment Strategies

• To inhibit detrimental pathways, beta-blockers are used alongside RAAS inhibitors like ACE inhibitors or ARBs. Diuretics help manage fluid retention but do not affect mortality rates.

• The primary goal of treatment is preventing ventricular remodeling; without intervention, the heart may change shape into a spherical form.

Pathophysiology of Heart Failure with Preserved Ejection Fraction

• Heart failure can be viewed as a significant bottleneck; elevated arterial pressure forces the left ventricle to work harder over time, leading to left ventricular hypertrophy.

• Increased atrial contraction becomes necessary for effective emptying as the left atrium enlarges due to pressure overload. This condition raises the risk for atrial fibrillation.

Consequences of Left Atrial Hypertrophy

• Eventually, if untreated, congestion occurs backward into pulmonary circulation causing pulmonary hypertension and systemic congestion due to elevated venous pressure.

Evolution of Hypertrophy in Heart Failure Patients

• Initially presenting with concentric hypertrophy (thickened walls but small cavity), untreated hypertension can progress into eccentric hypertrophy characterized by dilation despite similar weight.

Understanding Heart Failure Symptoms and Diagnosis

Key Symptoms of Heart Failure

• The mass of the left ventricle (Ve) increases, leading to hypertrophy, although wall thickness may not be significantly elevated.

• Important symptoms include progressive fatigue and orthopnea; these are critical indicators for identifying heart failure in clinical scenarios.

• Paroxysmal nocturnal dyspnea occurs when a patient experiences sudden shortness of breath after lying down for some time.

• Left-sided heart failure primarily manifests as pulmonary congestion, resulting in symptoms like exertional dyspnea, orthopnea, and cough due to bronchial congestion.

• Right-sided heart failure leads to systemic congestion with signs such as jugular venous distension, hepatomegaly, ascites, and peripheral edema.

Physiopathological Correlation of Symptoms

• A table correlating physiological events with symptoms shows that pulmonary congestion leads to orthopnea and nocturnal cough.

• Systemic congestion results in various symptoms including cold extremities and reduced urinary output due to low cardiac output.

• Diagnostic criteria for heart failure can be established clinically without the need for extensive testing; Framingham criteria are utilized.

Framingham Criteria for Diagnosis

• Two major or one major plus two minor criteria from the Framingham list are necessary for diagnosing heart failure effectively.

• Major criteria include paroxysmal nocturnal dyspnea and pulmonary crepitations while minor criteria may overlap with other conditions like ankle edema or tachycardia.

Role of BNP in Diagnosis

• B-type natriuretic peptide (BNP) serves as a significant marker; a low BNP level effectively rules out heart failure due to its high negative predictive value.

• An intermediate or high BNP level suggests the presence of heart failure; higher levels correlate with increased likelihood.

Additional Diagnostic Tools

• Echocardiograms help stage the disease and identify underlying causes but are not essential for initial diagnosis.

• Radiographic assessments can indicate cardiomegaly through specific measurements on chest X-rays.

Inadequate Heart Function: Key Insights

Understanding B Lines in Radiography

• The presence of B lines, known as Kerley B lines, indicates congestion and is typical in patients with acute heart failure. The severity of heart failure correlates with the prominence of these radiographic changes.

Electrocardiogram Findings

• An electrocardiogram (ECG) showing normal results is rare in cases of heart failure. Special attention should be given to branch block findings, particularly left and right bundle branch blocks.

Identifying Bundle Branch Blocks

• Left bundle branch block (LBBB) often suggests a need for cardiac resynchronization therapy, especially in patients with heart failure. Diagnosis involves recognizing wide RS complexes on the ECG.

• In lead V1, if the deflection is downward, it indicates LBBB; upward deflection signifies right bundle branch block (RBBB). This mnemonic aids in memorizing the identification process.

Importance of Echocardiograms

• Echocardiograms are essential for all heart failure patients to assess ventricular function, chamber size, valve function, and hemodynamic status. They should be repeated whenever there’s a change in clinical condition.

Cardiac Catheterization Indications

• Cardiac catheterization is warranted when ischemic origin is suspected. It’s particularly relevant for patients with chest pain or those at high risk due to factors like hypertension and diabetes.

Laboratory Tests Overview

• A complete blood count (CBC) is crucial as anemia can worsen prognosis in heart failure patients. Monitoring electrolytes such as sodium and potassium is also important due to their prognostic implications.

Additional Laboratory Considerations

• Arterial blood gas analysis may be necessary if signs of hypoxemia or tissue hypoperfusion are present. Renal function must also be assessed since both renal hypoperfusion and congestion can occur.

• Troponin levels help diagnose potential coronary syndromes when uncertainty exists regarding diagnosis. BNP levels provide negative predictive value for heart failure diagnosis.

Other Relevant Tests

• Hepatic function tests may reveal elevated bilirubin levels related to congestive symptoms. Iron studies are significant since iron deficiency correlates with worse outcomes in heart failure.

Conclusion & Course Promotion

• The session concludes with gratitude towards participants and an invitation to continue learning about heart failure treatment from Professor Juan.

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