From the Guidelines
A Left Heart Catheterization (LHC) would not show Pulmonary Embolism (PE) as it is not designed to visualize the pulmonary arteries or diagnose PE. Instead, imaging studies such as CT pulmonary angiography (CTPA), ventilation-perfusion (V/Q) scan, or pulmonary angiography are used to diagnose PE. CTPA is considered the gold standard test and provides detailed images of the pulmonary arteries, allowing for direct visualization of clots blocking blood flow 1. V/Q scans assess blood flow and air distribution in the lungs, with mismatched defects suggesting PE. Pulmonary angiography is an invasive procedure involving contrast injection directly into the pulmonary arteries. D-dimer blood tests are often used as an initial screening tool, but a positive result requires confirmation with imaging 1. The diagnosis of PE has been facilitated by technical advancements and multidetector CT pulmonary angiography, which is the major diagnostic modality currently used 1. It's worth noting that LHC is not a medical imaging device, and medical professionals would never use it for medical diagnosis as it's designed for particle physics experiments, not medical imaging. Some key points to consider when diagnosing PE include:
- Clinical decision trees, such as the Wells criteria, have been developed and validated to estimate the pretest likelihood of PE 1.
- High-sensitivity D-dimer testing using an enzyme-linked immunosorbent assay has improved the specificity of the diagnosis of PE, but it is of limited value in certain patient populations, such as pregnant, postoperative, and trauma patients 1.
- A negative D-dimer test effectively excludes PE or DVT in patients with a low pretest probability of PE 1. In terms of the most recent and highest quality study, the 2022 update of the ACR Appropriateness Criteria for suspected pulmonary embolism recommends the use of CT pulmonary angiography as the primary diagnostic modality for PE 1.
From the Research
Diagnostic Methods for Pulmonary Embolism (PE)
- Computed Tomography Pulmonary Angiography (CTPA) is the current standard of care for diagnosing PE, providing accurate diagnosis with rapid turnaround time 2.
- D-dimer test is a laboratory assay used to rule out the presence of high D-dimer plasma levels and, by association, venous thromboembolism (VTE) 3.
- Ventilation-perfusion (VQ) scan, magnetic resonance imaging (MRI), and catheter pulmonary angiography are other diagnostic methods used for PE, but with varying degrees of utility and availability 2.
Left Heart Catheterization (LHC) and Pulmonary Embolism (PE)
- There is no direct evidence to suggest that LHC would show PE, as LHC is primarily used to diagnose and treat conditions affecting the left side of the heart, such as coronary artery disease and heart valve problems.
- PE is a condition that affects the pulmonary arteries, which are not directly visualized during an LHC procedure.
- Diagnostic methods such as CTPA, D-dimer test, and VQ scan are more suitable for diagnosing PE 4, 5, 6, 2, 3.
Limitations of Diagnostic Methods
- D-dimer test has high sensitivity but low specificity, resulting in high levels of false-positive results, especially among older populations 3.
- CTPA has a high degree of accuracy, but may not be suitable for patients with certain medical conditions, such as kidney disease or allergy to contrast agents 2.
- VQ scan and MRI have limited availability and may not be suitable for all patients, especially those with certain medical conditions or implants 2.