Cardiology diagnostic tests and procedures

Methods for diagnosing heart conditions

Diagnostic tests in cardiology are used to identify various cardiac conditions by evaluating heart structure, function, and electrical activity. These tests can be non-invasive or invasive and are used in both emergency and outpatient settings to aid in the diagnosis and management of cardiovascular disease.

Bedside Assessment

Medical History

Obtaining a thorough medical history is the first and most essential step in evaluating cardiac health. While some symptoms such as chest pain, dyspnea, or palpitations may point to significant heart disease, other symptoms may be absent or misleading. Consequently, history alone is rarely sufficient to confirm or rule out a cardiac condition.

Auscultation

Auscultation using a stethoscope allows clinicians to listen for normal and abnormal heart sounds, such as murmurs, gallops, and pericardial rubs. These may suggest underlying structural or functional abnormalities of the heart valves or chambers.

Laboratory Investigations

Blood Tests

Various blood tests help in the evaluation of cardiovascular risk and myocardial injury:

• Lipid profile – Total cholesterol, LDL, HDL, triglycerides
• C-reactive protein – Marker of inflammation
• Homocysteine
• Fibrinogen
• Ferritin
• Troponin – Highly specific marker for myocardial infarction
• Creatine kinase (CK-MB)
• Brain natriuretic peptide (BNP) – For heart failure
• Glucose and insulin levels – For assessing diabetes mellitus and insulin resistance

Additional tests include Lipoprotein(a), fasting insulin, HbA1c, and myoglobin.

Cardiovascular Risk Profile Table

Test	Normal/Low Risk	High Risk	Approximate Cost (USD)
Total Cholesterol	<200 mg/dL	>240 mg/dL	$50
LDL-C	<100 mg/dL	>160 mg/dL	$150*
HDL-C	>60 mg/dL	<40 mg/dL	$50
Triglycerides	<150 mg/dL	>200 mg/dL	$75
Blood Pressure	<120/80 mmHg	>140/90 mmHg	Variable
C-Reactive Protein	<1 mg/L	>3 mg/L	$20
Fibrinogen	<300 mg/dL	>460 mg/dL	$100
Homocysteine	<10 μmol/L	>14 μmol/L	$200
Fasting Insulin	<15 μIU/mL	>25 μIU/mL	$75
Lipoprotein(a)	<14 mg/dL	>19 mg/dL	$75
Coronary Calcium Score	<100	>300	$250–600

• LDL-C is often calculated using the Friedewald formula due to cost.

Electrophysiology

Electrocardiogram (ECG or EKG)

An electrocardiogram records the heart’s electrical activity and is a cornerstone in diagnosing arrhythmias, myocardial infarction, electrolyte imbalance, and cardiac ischemia. A standard 12-lead ECG provides a comprehensive view of cardiac conduction in multiple planes.

Holter Monitor

A Holter monitor is a portable ECG device that continuously records for 24–48 hours. It is useful for detecting frequent but transient arrhythmias.

Event Monitor

An event monitor records heart rhythms for 1–2 weeks and is triggered by the patient when symptoms occur. It is suitable for detecting infrequent arrhythmias.

Cardiac Stress Testing

Cardiac stress testing assesses the heart’s response to exertion. It may be done using exercise or pharmacologic agents. Radionuclide imaging (e.g., with thallium or technetium) can be combined to identify areas of ischemia.

Target heart rate is commonly calculated as:

• 220 - age (in beats per minute)
• Alternate formulas include:

Miller: 217 - (0.85 × Age)

High-frequency QRS complex analysis may improve sensitivity for detecting coronary artery disease during stress testing.

Electrophysiology Study (EPS)

An electrophysiology study is an invasive test using intracardiac catheters to map the heart’s conduction system. It is typically used to evaluate unexplained arrhythmias or assess suitability for radiofrequency ablation.

Medical Imaging

Cardiac Imaging Techniques

• Echocardiography – Evaluates heart chambers, valves, and function.
• Coronary catheterization – Invasive procedure to visualize coronary arteries.
• Intravascular ultrasound (IVUS) – Visualizes vessel walls from inside arteries.
• Coronary calcium scan – Detects coronary artery calcification.
• Retinal vessel analysis – Evaluates microvascular changes reflecting cardiac health.

See Also

• Cardiac imaging
• Electrocardiography
• Stress test
• Cardiac catheterization
• Arrhythmia
• Heart failure
• Coronary artery disease
• Cardiac biomarkers