14. TESTS ASSOCIATED WITH CARDIAC DISORDERS

Tests associated with cardiac disorders help evaluate the structure, function, and performance of the heart. These diagnostic tools play a crucial role in identifying conditions such as myocardial infarction, arrhythmias, heart failure, ischemic heart disease, and valvular disorders. Understanding cardiac diagnostic tests enables clinical pharmacists and healthcare professionals to interpret results, monitor drug therapy, and optimize patient care.

Electrocardiogram (ECG / EKG)

An Electrocardiogram records the electrical activity of the heart. It is a simple and essential investigation in cardiac assessment.

Uses of ECG

  • Diagnosis of arrhythmias (e.g., atrial fibrillation, ventricular tachycardia).
  • Detection of myocardial ischemia and infarction.
  • Monitoring drug effects (e.g., digoxin, antiarrhythmics).
  • Identifying conduction abnormalities like AV block.

Common ECG Findings

  • ST elevation: Acute myocardial infarction.
  • ST depression: Myocardial ischemia.
  • Prolonged QT interval: Risk of torsades de pointes.
  • Peaked T waves: Hyperkalemia.

Cardiac Biomarkers

Cardiac biomarkers increase in the blood when there is damage to the heart muscle. They are crucial in diagnosing acute coronary syndromes (ACS).

1. Troponins (cTnI, cTnT)

Troponins are the most sensitive and specific biomarkers for myocardial infarction.

  • Rise within 3–6 hours after heart damage.
  • Remain elevated for up to 7–14 days.
  • Indicate severity of myocardial injury.

2. Creatine Kinase-MB (CK-MB)

  • Rises within 4–6 hours after MI.
  • Useful to detect reinfarction due to shorter half-life.

3. Myoglobin

  • Earliest biomarker to rise (1–2 hours).
  • Not specific to cardiac muscle.

4. BNP and NT-proBNP

Markers for heart failure.

  • Elevated in left ventricular dysfunction.
  • Used to monitor severity and treatment response.

Echocardiography

Echocardiography uses ultrasound waves to evaluate the structure and function of the heart.

Uses of Echocardiography

  • Assessment of ejection fraction (EF).
  • Diagnosis of valvular heart diseases (stenosis, regurgitation).
  • Detection of heart failure and cardiomyopathy.
  • Identify pericardial effusion.

Stress Testing

Stress tests evaluate the heart’s response to exertion. They help diagnose coronary artery disease (CAD).

Types of Stress Tests

  • Exercise Stress Test: Using treadmill or bicycle.
  • Pharmacological Stress Test: Using agents like dobutamine or adenosine.

Indications

  • Suspected angina.
  • Evaluation of cardiac fitness.
  • Assessment of therapy response in CAD.

Chest X-Ray (CXR)

Chest X-rays give information about the size and shape of the heart and lungs.

Findings in Cardiac Disorders

  • Cardiomegaly: Seen in heart failure.
  • Pulmonary edema: Fluid overload in cardiac failure.

Cardiac CT and MRI

Cardiac CT

  • Used for coronary calcium scoring.
  • Helps detect coronary artery stenosis.

Cardiac MRI

  • Best for soft tissue characterization.
  • Diagnoses myocarditis, cardiomyopathy, and fibrosis.

Lipid Profile

Lipid profile tests evaluate cardiovascular risk.

Components

  • Total Cholesterol
  • LDL (bad cholesterol)
  • HDL (good cholesterol)
  • Triglycerides

Clinical Significance

  • High LDL and triglycerides increase risk of CAD.
  • Statins and lifestyle changes help lower lipid levels.

Blood Pressure Measurement

Essential for diagnosing hypertension and monitoring cardiovascular health.

Hypertension Classification (Simplified)

  • Normal: <120/80 mmHg
  • Stage 1: 130–139/80–89 mmHg
  • Stage 2: ≥140/90 mmHg

Holter Monitoring

Holter monitoring is a 24–48 hour continuous ECG recording.

Uses

  • Diagnoses intermittent arrhythmias.
  • Evaluates unexplained dizziness or palpitations.
  • Monitors pacemaker function.

Coronary Angiography

An invasive imaging test used to visualize coronary arteries.

Indications

  • Unstable angina.
  • Acute myocardial infarction.
  • Pre-operative cardiac evaluation.

Findings

  • Stenosis: Narrowing of coronary arteries.
  • Blockage: Complete occlusion requiring stent or bypass.

Common Cardiac Disorders Identified With These Tests

  • Myocardial infarction
  • Angina pectoris
  • Heart failure
  • Arrhythmias
  • Hypertrophic and dilated cardiomyopathy
  • Valvular heart diseases
  • Pericarditis and myocarditis

Detailed Notes:

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