Week 10: Cardiology Part 5/5: Clots and Valves

Pulmonary emboli most commonly result from deep venous thrombi in the legs that move and pass through the right ventricle into the pulmonary vasculature. The emboli can lodge anywhere across the pulmonary circulation including the main pulmonary arteries or at the smallest subsegmental levels. Traditional chest radiography rarely provides information helpful in identifying pulmonary embolism as the definitive cause of a patient’s symptoms but may suggest alternative causes. Westermark’s sign is a rare finding on chest X-ray representing oligemia of the pulmonary vasculature visualized distal to the site of embolism.

The pulmonary embolism rule-out criteria (PERC) is a decision rule applied to patients with a low pretest probability (< 15%). If none of the criteria are present, the patient’s pretest probability is decreased to < 2% and further diagnostic testing is not recommended.

Well’s Clinical Prediction Criteria is a clinical prediction and risk stratification tool used to quantify a patients pre-test probability of pulmonary embolism (PE). The criteria should be applied only after a history and physical suggests that venous thromboembolism is a diagnostic possibility. It should not be applied to all patients with chest pain or dyspnea or to all patients with leg pain or swelling. While there have been modified versions since its first publication in 2000, the original scoring systems involves 7 risk factors. These factors include: (1) Clinical signs and symptoms of deep vein thrombosis (DVT); (2) An alternative diagnosis is less likely than PE; (3) HR > 100; (4) Immobilization at least 3 days or surgery in the previous 4 weeks, previous;  (5) Objectively diagnosed PE or DVT; (6) Hemoptysis; and (7) Malignancy with treatment within 6 months or palliative. The patient in the above clinical scenario only has a heart rate greater than 100 beats per minute which constitutes a Well’s score of 1.5. She has no further risk factors according to Well’s Criteria. This risk stratification tool has been validated in several studies since its publication and is widely used for stratifying patients who may need further evaluation for PE with a d-dimer or CT angiogram. It is important to note that Well’s criteria have not been validated for use in pregnant females or patients less than eighteen years of age. The scoring system stratifies patients into low risk (1.3% chance of PE), moderate risk (16.2% chance of PE), and high risk (40.6% risk of PE).

This patient presents with a low-risk story for pulmonary embolism but one that cannot be ruled out by history and physical alone. Clinicians can determine low, moderate and high risk based on clinical gestalt or using a scoring system like the Wells’ Criteria seen below.

In patients who are low risk either by clinical gestalt or Wells’ criteria, the PERC rule, seen below, can be applied.

Since the patient takes oral contraceptives so she does not meet the PERC rule criteria. However, since she is low risk according to the Wells’ criteria, a d-Dimer should be obtained.

The correct answer is pulmonary embolism. CXR shows a Hampton’s hump, suggestive of a large infarction due to pulmonary embolism. Further, patients with pulmonary hypertension are at extremely high risk for PE.

Needle thoracostomy and decompression of the tension pneumothorax is indicated prior to any other interventions. COPD increases the prevalence of spontaneous pneumothoraces secondary to ruptured blebs and deformed lung parenchyma. Intubation may be required for the pulseless arrest described, but the most likely cause of this COPD patient’s sudden decompensation is a spontaneous tension pneumothorax which necessitates release via needle thoracostomy

This clinical scenario demonstrates acute pulmonary embolus. With the history of Factor V Leiden disease, this patient is predisposed to thrombotic events. With the acute onset of dyspnea, the presence of DVT in her right leg, tachypnea, and tachycardia, one must suspect PE. The treatment of PE largely depends on the clinical scenario and how stable the patient is. In this case, the patient has hemodynamic instability with evidence of altered mental status. IV thrombolytics should be given immediately. Plasmophoresis is not an indicated treatment in PE.

The correct answer is admission and heparin infusion. This patient has a pulmonary embolism but no right sided heart strain.  Emergent thrombolytic therapy is not indicated, but mortality is significant enough to warrant admission and monitoring. Patients with massive acute pulmonary embolism who have failed thrombolytics or have contraindications to thrombolytics may be considered for embolectomy. However, this patient is hemodynamically stable so embolectomy is not indicated emergently at this time. Thrombolytics are controversial in that limited studies have shown improved hemodynamics but no mortality benefit. That being said, in patients with massive acute pulmonary embolism and persistent and/or worsening hemodynamic instability, many guidelines suggest considering administration of thrombolytics. This patient is stable and so the risk of thrombolytics is too great.

The sensitivity of a single scan is 95%. Thus, 5% are missed.

In moderate- to high-risk patients with an elevated D-dimer level, a single ultrasound examination may be insufficient. A repeated study in 2 to 7 days is often sufficient to confirm the diagnosis. The lack of pulmonary symptoms precludes the need for lung and embolus evaluation at this time. During pregnancy, there is a progressive rise in baseline D-dimer concentration; thus, a “normal” value is useful, but an elevated level is of no discriminatory value.