Tanzania Medical Students Association

IR case of the month

TAMSA IR CASE # 2

 

Patient details and symptoms:

 

A 52-year-old man with uncontrolled hypertension, reporting chest pain and shortness of breath at rest. Upon further questioning, he reveals that he has had right calf pain for one month.

Physical examination: 

     Temperature: 370C

     Pulse: 102 bpm 

     Respirations: 17 breaths per min

     Blood pressure: 170/110 mmHg

     SpO2: 93% on room air

 

Laboratory results: 

     Hb 14.3g/dl

     PLT  245,000/μL

     INR 1.1

     D-dimer 2350

CT Pulmonary Angiogram was obtained, revealing a large filling defect within the right lower pulmonary artery.

Diagnosis: Pulmonary embolism 

Fig. 1 CT Pulmonary Angiogram demonstrating a pulmonary embolism

Thanks to Dr. Murray R. Asch for providing this image

Venous thromboembolism (DVT and PE):

Abbreviations: 

      VTE: Venous thromboembolism

      DVT: Deep vein thrombosis 

      PE: Pulmonary embolism 

      IVC: Inferior vena cava 

 

Venous thromboembolism (VTE) is a condition where a thrombus, which is a blood clot in a vein, dislodges and travels to another part of the body, with the potential to cause partial or complete occlusion of a blood vessel. Most commonly, thrombi form in the deep vein system of the legs and pelvis, termed deep vein thrombosis (DVT). A common complication of DVT is embolization of the thrombus to the pulmonary arteries, causing pulmonary embolism (PE). DVT may prove fatal if leading to a large PE, such as one occluding the bilateral pulmonary arteries, called a saddle pulmonary embolism. Non-fatal events may cause serious long-term conditions such as post-thrombotic syndrome and chronic pulmonary hypertension.

 Fig 2. Image depicting normal blood flow in veins (centre image) compared to DVT with embolus formation (right image)

Image from Ausmed.com

Patients with VTE may present with a broad spectrum of symptoms, ranging from mild calf pain due to DVT, to unstable vital signs in a patient with a large saddle PE

Signs and Symptoms of VTE: 

     Tachypnea (very frequent) 

     Dyspnea

     Diaphoresis

     Pleuritic chest pain

     Cough

     Heart palpitations 

     Syncope or presyncope

     Wheezes

     Low grade fever

     Hypotension

     Positive Homan’s Sign (calf pain on dorsiflexion of foot)

     Hemoptysis

     Leg pain

     Leg edema

 

Risk Factors:

Risk factors for VTE can be categorized according to a triad called Virchow’s Triad. This includes, venous stasis, endothelial injury and a hypercoagulable state. The risk of VTE increases with the number of Virchow’s Triad components that are present. 

Causes of venous stasisinclude long periods of immobility, such as long airplane flights, paralysis, venous insufficiency, varicose veins, venous obstruction from a tumour or due to obesity or pregnancy. 

Causes of a hypercoagulable stateinclude thrombophilia, sepsis, active malignancy, estrogen therapy such as oral contraceptives, as well as pregnancy and the peripartum state. 

Lastly, causes of endothelial injury include, trauma, recent surgery, smoking, atherosclerosis, chemical irritation, and instrumentation such as placement of intraluminal catheters or venipuncture. 

Having previously been diagnosed with PE or DVT is also a major risk factor for the development of a subsequent DVT or PE. 

Fig 3. Virchow’s Triad

Image from Sciencedirect.com

Diagnosis: 

Diagnostic workup typically begins with a chest radiograph to exclude other common causes of chest pain and shortness of breath.  AD-dimer is a sensitive but non-specific test for VTE, meaning that it is elevated with many disease processes. It is, however,an excellent test to exclude VTE.  In 2019, the gold standard for diagnosis of DVT is compression ultrasoundof the lower extremities. If there is a high suspicion for PE, then CT pulmonary angiogram (CT-PA) is the diagnostic test of choice. CT-PA requires contrast administration, which may be contraindicated, such as with chronic kidney disease (eGFR <30 mL/min).Other imaging options includeVentilation Perfusion (V/Q) scans and echocardiography.

Treatment:

      Prevention:

      Ambulation, compression stockings, prophylactic anticoagulants in high risk patients

      Supportive therapy with oxygen and fluids

      Prompt anticoagulation (typically acutely with fractionated or unfractionated heparin)

      Note that heparin prevents clot formation; does not lyse clot

      Thrombolytic agents

     Tissue plasminogen activator (TPA)

      Placement of IVC filter in patients who cannot be anticoagulated

      Mechanical thrombolysis or endovascular stent placement

Indications for IVC filter placement include documented VTE, as well as one or more of the following:

1. An existing absolute contraindication to anticoagulation.

2. Complication of anticoagulation resulting in cessation of the therapy.

3. Failure of anticoagulation.

Role of interventional radiology (IR):

Inferior Vena Cava (IVC) filters are placed to prevent pulmonary embolism. They are most commonly used when there is a contraindication to anticoagulation. The filters are a form of wire lattice, with a narrow distal end preventing thrombi from travelling proximally towards the pulmonary arteries. The clot becomes trapped in the filter until it is dissolved by components of the blood. There are two types of IVC filters, permanent or retrievable.

 

Retrievable filters

Retrievable IVC filters are used to provide protection from PE during a period of risk, such as surgery. These filters are used with the intention of being removed once the period of risk for clot formation has passed. Some retrievable filters can only be removed within a specified time frame, and if left for longer, there is a risk of incorporating into the IVC wall and becoming permanent. However, retrievable filters have been designed so that they can be left in place permanently.

 

Permanent filters

Permanent filters are, by definition, intended to be left in place for life. 

 

Fig 4. IVC filter in situ with trapped clot    

   

Fig 5. CT scan demonstrating IVC filter in situ 

   

Fig 6. IVC filter with multiple trapped thrombi

 

Thanks to Dr. Murray R. Asch for providing this image

Comments

The ability to remove an IVC filter led to a significant increase in use shortly after development of optional filters. Some filters were rapidly brought to market before long term data on safety was available.  After a number of filter related deaths, in 2010 the FDA (U.S. Food and Drug Administration) issued a warning recommending removal of all retrievable IVC filters when no longer clinically indicated.  In patients who could not have filters removed for medical or technical reasons, there should be regular imaging monitoring to ensure the filter does not fracture or migrate.  

 

 

 

Prepared by:

Evarist Nyahinga, 5th year Medical Student at Kampala International University in Tanzania (KIUT)

 

Assistance by:

Nancy Kaur, Medical Student, Munich, Germany

Dr. Murray Asch, Staff IR, Oshawa, Ontario, Canada

Victoria Domonkos, Medical Student, Thunder Bay, Canada

 

Resources:

  1. American Thoracic Society (2010). Pulmonary Embolism. Retrieved from: https://www.thoracic.org/patients/patient-resources/resources/pulmonary-embolism.pdf
  2. AusMed (2018). Pulmonary Embolism - DVT to PE. Retrieved from: https://www.ausmed.com/cpd/articles/pulmonary-embolism (used for illustrations and diagrams). 
  3. Kessel, D., & Robertson, I. (2017). Interventional Radiology - A Survival Guide, 4th Edition. Elsevier.

 

 

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