Cardiac Ultrasound vs. Echocardiogram: What's the Difference?

As a young medical professional, you're likely familiar with the concept of cardiac imaging but may find yourself needing a refresher on the nuances between cardiac point of care ultrasound (POCUS) and echocardiogram. While used interchangeably in some contexts, understanding their distinctions is crucial for accurate diagnosis and optimal patient management.

The Foundation: Ultrasound Technology

Both cardiac POCUS and echocardiograms leverage high-frequency sound waves to generate images of the heart in real time. These echoes form the basis of image analysis, with no ionizing radiation involved.

Cardiac POCUS: A Structural and Functional Overview

A cardiac POCUS provides a general assessment of cardiac anatomy and function, including:

• Morphometrics: Evaluation of heart chamber dimensions and wall thicknesses (e.g., identifying left ventricular hypertrophy in hypertension).
• Systolic function: Global and segmental wall motion analysis offers a qualitative and sometimes quantitative measure of left ventricular ejection fraction.
• Hemodynamics: Doppler interrogation at rudimentary levels can suggest valvular stenosis or regurgitation, as well as signs of elevated filling pressures. But POCUS has its disadvantages as you can´t grade the severity of the stenosis or the regurgitation.
  
  

Echocardiogram: The Heart Valve and Flow Specialist

An echocardiogram is a specialized cardiac ultrasound with a primary focus on valve pathology and detailed hemodynamic assessment. Key applications include:

• Valvular analysis: Meticulous visualization of all four cardiac valves, quantifying the severity of stenosis or regurgitation through different parameters such as pressure gradient calculations, maximum velocity etc.
• Advanced hemodynamics: In addition to basic Doppler techniques, advanced tools such as PISA (Proximal Isovelocity Surface Area) and vena contracta enable accurate quantification of regurgitant volumes in cases of valvular insufficiency. When assessing stenosis, measurements like pressure half-time (PHT) and maximum velocity serve as valuable indicators among various grading methods for severity assessment.
• Specialized applications: Sub-types of echocardiograms like transesophageal echocardiograms (TEE) provide high-resolution views of posterior structures, while stress echocardiograms evaluate functional reserve and potential ischemia.
  
  

Diagnostic Decision-Making

Choosing the appropriate imaging modality depends on the clinical context:

• Broad screening: In a patient with undifferentiated dyspnea, chest pain or palpitations, a cardiac POCUS is often the initial step to screen for structural abnormalities, wall motion abnormalities or overt systolic dysfunction.
• Targeted investigation: If valve pathology is suspected or if precise hemodynamic data is required, an echocardiogram provides the necessary level of detail for diagnosis and treatment planning.
  
  

The Procedures: What to Expect

The technical aspects are similar for both tests:

1. Patient positioning: Typically supine with slight left lateral decubitus position. To obtain the subcostal view, the patient should lie in a supine position.
2. Electrode placement: ECG lead placement for rhythm monitoring.
3. Image acquisition: Transducer is placed on/below the chest in a variety of standard parasternal, apical and subcostal views to capture comprehensive diagnostic images.
   
   

Empowering Young Professionals

A solid grasp of the differences between cardiac POCUS and echocardiogram is essential for young medical practitioners to accurately interpret results and tailor patient care plans. Remember, these tools play a vital role in the cardiology arsenal, providing a window into the heart that helps us deliver life-saving treatments.