Pulmonary Thromboembolism

As mentioned, the most common cause of PTE is a clot in the leg veins. This DVT most commonly occurs secondary to immobility. The people who have had a recent surgery which causes decreased leg movements or those who are bedridden due to other conditions are at risk for deep vein thrombosis. Occasionally the PTE can be secondary to air embolism or fat embolism due to trauma and fracture of long bones on the limbs.

• Patients having recent surgeries to the legs or any surgery causing prolonged immobility and bed rest
• Long travel with sitting in a vehicle or planes for prolonged time
• Cancer patients have more risk for DVT and PTE
• Patients with heart conditions
• Smokers
• Patients with hematological conditions that can affect clotting of blood
• Covid virus infection has caused an increase in the incidence of DVT and PTE. Its vaccine has also been suggested to cause the same
• Obesity or being overweight is also a risk factor
• Pregnancy can occasionally cause compression of the abdominal veins and predispose to DVT and subsequently PTE
• Certain hormonal pills for replacement therapy or birth control have also been found to be correlated with occurrence of DVT and PTE

Symptoms of PTE can vary depending on the clot burden, the duration of the disease and the amount of lung involved. Patients may be occasionally asymptomatic. Most common symptoms include -

• Shortness of breath on exertion
• Chest pain - sharp type pain more commonly on deep breathing or on coughing
• Dizziness can occur as it can cause drop in the blood pressure
• Hemoptysis or coughing of blood
• These patients can also have simultaneous symptoms of DVT i.e. pain in the legs

• Astute clinical judgment to suspect PTE is paramount in diagnosing the condition
• ECG - can show sinus tachycardia or S1Q3T3 pattern
• Echocardiogram - can show dilation of right ventricle with impairment of its function and raised right sided pressures. Occasionally a clot may be seen on the echocardiogram in the main pulmonary artery or its branches
• D dimer levels - can be sent occasionally if there is suspicion of PTE. If high, then these patients should undergo CT scan of the lung arteries
• CT scan - CTPA i.e CT scan of the pulmonary arteries is the gold standard to diagnose PTE. It is a contrast scan, so has to be done with caution in patients with abnormal kidney functions
• Ultrasound, i.e sonography of the leg veins with doppler can identify DVT and thus can be a strong indicator of subsequent PTE
• In exceptional cases, MRI of the lungs or ventilation perfusion scan can be done to diagnose PTE where CT cannot be done to avoid radiation i.e. in pregnancy

Depending on the symptoms of the patient and the clot burden, the treatment plan is decided.

Medical Management

Blood thinners or anticoagulants - these are started to prevent further clot formations. These can be injectables in the form of heparin or tablets in the form of warfarin or DOAC (directly acting oral anticoagulants) like dabigatran, apixaban, edoxaban or rivaroxaban.

Thrombolytics

These injections are given for life threatening PTE. These medications help in lysing i.e dissolving the formed clots. Thrombolysis is similar to the treatment done for heart attacks and the injections that can be used are tenecteplase or reteplase and occasionally streptokinase.

Surgical Procedures

Catheter directed thrombolysis - can be done when there is great thrombus burden and some risk for bleeding. The advantage of it is that the injections are given directly into the arteries of the lungs where the clot is, via the catheters that are passed through the groins vessels.

Mechanical thrombectomy - this can remove clots from the lung arteries directly via special catheters that can suck out the clots.

IVC filter - this can be occasionally placed if the burden of DVT in the legs is high and the patient cannot take blood thinners because the risk of bleeding is high or has to undergo some major surgeries in the immediate future.

• Physical activity is the best remedy for prevention of DVT and subsequently PTE
• When there is immobility, blood thinners can be given as a preventative measure
• Also, stocking or pneumatic compression may be prescribed for the legs
• Plenty of fluids should be advised
• While traveling, people should take breaks from sitting for prolonged periods and they should also move their calf muscles and ankles to decrease stasis of blood flow in the lower legs

Complications if not treated

As mentioned previously, if not treated promptly, this condition can be life threatening. If untreated it can also cause long term issues like development of pulmonary hypertension which can cause fatigability or worsening shortness of breath and swelling over the feet. This can cause severe impairment of the activities of daily living and can also decrease life expectancy.