Vascular Medicine. Thomas Zeller
clinical probability of pulmonary embolism and deep venous thrombosis is estimated as described above.
ECG
Laboratory findings
– Negative findings (< 500 μg/L) practically exclude pulmonary embolism; i.e., in 30% of patients with emergency admission, but fewer than 10% of inpatients, pulmonary embolism can be excluded using d-dimer assessment.
– Caution: d-dimers are also raised in infection, inflammation, carcinoma, status post surgery, cardiac insufficiency and renal insufficiency, acute coronary syndrome, pregnancy, and sickle-cell crisis.
– Troponin: evidence of hemodynamically significant pulmonary embolism, right ventricular enlargement, right cardiac ischemia
– Protein C
– Protein S
– Angiotensin III
– APC resistance
– Rheumatism serology, including anticardiolipin
Chest x-ray
Nonspecific changes include:
An unremarkable chest x-ray does not exclude pulmonary embolism.
Diagnosis of deep venous thrombosis
Table 2.2–1 Pathophysiology of pulmonary embolism.
| Pulmonary artery obstruction → afterload increase for RV → walltension ↑, RV ischemia, RV decompensation, acute cor pulmonale →RV output ↓, RV volume ↑, septal deviation → LV preload ↓, cardiac output ↓ → RV coronary perfusion ↓ → right heart failure |
| Inhomogeneous perfusion → wasted ventilation → hypoxemia |
| Released mediators (thromboxane A2, serotonin, fibrinopeptides, leukotriene) → vasoconstrictio |
RV, right ventricle; LV, left ventricle.
Table 2.2–2 Clinical probability of pulmonary embolism (adapted from Perrier).
| High (80–100%) | Risk factor present, otherwise unexplained dyspnea, pleuritic pain, gas exchange disturbance or abnormalities on chest x-ray |
| Intermediate (20–79%) | Neither high nor low probability of pulmonary embolism |
| Low (0–19%) | No risk factors present, clinical symptoms and findings explicable by other causes |
Table 2.2–3 Severity of pulmonary embolism (adapted from Grosser).
BP, blood pressure.
Echocardiography (transthoracic echocardiography, transesophageal echocardiography)
– Dilated, hypokinetic RV
– Raised RV/LV ratio
– Deviation of the intraventricular septum in LV
– Dilated proximal pulmonary arteries
– Regurgitation via the tricuspid valve (jet: 2.5–2.8 m/s)
– Dilated inferior vena cava without collapse on inspiration
– Myocardial infarction
– Valvular insufficiency
– Hypovolemia
– Endocarditis
– Aortic dissection
– Pericardial tamponade
Ventilation–perfusion scintigraphy
Only applicable with normal findings (15%) → exclusion of pulmonary embolism, high-probability finding (13%) → treatment. When ventilation–perfusion scintigraphy is not diagnostic—i.e., in approximately 70% of cases—further diagnostic procedures are necessary.
Spiral CT
It is recommended that spiral CT should be used in combination with the clinical findings, laboratory