Management of straddling thrombus through patent foramen ovale complicating pulmonary embolism

Abstract

A 60-year-old man was admitted to intensive care unit with the diagnosis of pulmonary embolism. Bedside transthoracic echocardiography revealed the extension of the thrombus into left atrium and ventricle through patent foramen ovale (PFO). A straddling thrombus also described as impending paradoxical embolism is a rare condition when thrombus embolised to the heart gets caught in PFO. Morbidity is extremely high in case of systemic embolisation. Due to rarity, the treatment options are mainly individualised and no guidelines exist. There are few treatment strategies described in literature from surgical to interventional radiology to conservative approach. Treatment strategy should take individual parameters such as patient’s age, haemodynamic stability, bleeding risk and comorbidities into consideration. Our patient successfully underwent emergency surgical thrombectomy.

Case presentation

We present a case of a 60-year-old man who was transferred from peripheral hospital with submassive pulmonary embolism when he was being evaluated for sudden onset dyspnoea. His ECG showed S1Q3T3 pattern. CT pulmonary angiogram done in peripheral hospital revealed moderate clot burden with bilateral lobar artery occlusion. Troponins were negative. Patient was haemodynamically stable. Patient was commenced on heparin infusion and transferred to our intensive care unit for further management and monitoring.

This is on the background of having electively operated 2 days ago for resection of bladder and prostate. He was being evaluated for possible prostate cancer. Patient was on deep vein thrombus (DVT) prophylaxis perioperatively and was ambulatory. Other medical history included type II diabetes mellitus, hypertension, chronic kidney disease with baseline creatinine of 160 µmol/L and Estimated glomerular filtration rate (eGFR) of 38, previous DVT in 2013. He was then treated with warfarin for 6 months and was on lifelong aspirin (which was withheld for a week before the procedure). In intensive care unit, patient was haemodynamically stable with blood pressure of 110/60 mm Hg, afebrile, heart rate of 100 beats/min, saturating 96% on room air.

Our patient was at a significant risk for thromboembolism as he had a background of previous unprovoked thrombus on lifelong aspirin which was ceased a week before the procedure and a possible new prostate cancer was on top of our list of risk factors apart from diabetes related vasculopathy.

Investigations

Transthoracic echocardiography revealed a large (72×14 mm) highly mobile heterogeneous echogenic structure with independent motion identified in right atrium through to right ventricle suggesting thrombus in transit. The thrombus also appeared to be seen in left atrium passing through patent foramen ovale (PFO) with signs suggestive of acute right heart strain (figure 1—right ventricular inflow view in parasternal long axis).

Figure 1.

Transthoracic echo demonstrating thrombus in right ventricular inflow view in parasternal long axis. RV, Right Ventricle; RA, Right Atrium.

Transoesophageal echocardiography was also done which revealed a straddling thrombus extending into both ventricles from the atria during diastole through PFO. Right ventricle was mildly dilated and hypertrophied with normal function. Mild tricuspid regurgitation with mildly dilated right atrium was noted (figure 2—mid-oesophageal view).

Figure 2.

Transoesophageal echo demonstrating straddling thrombus extending into both ventricles from the atria through patent foramen ovale in mid-oesophageal view at level of short axis of the aortic valve. AV, Aortic Valve; LA, Left Atrium

Lower extremity Doppler ultrasound showed DVT of the left peroneal vein.

Treatment

Because of the large clot burden as well as impending paradoxical embolisation, the patient underwent emergency sternotomy, thrombectomy, and closure of PFO.

Median sternotomy was performed and patient was put on cardiopulmonary bypass. Inferior vena cava was snared and right atrium was opened obliquely parallel to the atrioventricular groove. PFO was dissected to provide an opening into the left atrium and around 15 cm clot was removed intact (figure 3). A small longitudinal pulmonary arteriotomy was fashioned; the main and central branch pulmonary arteries were inspected for thrombus. None were identified. Interatrial septum was closed in two layers. Total bypass time was 59 min with cross clamp time of 28 min.

Figure 3.

Postsurgical specimen of thrombus.

Outcome and follow-up

Open pulmonary embolectomy was successful and patient was continued on systemic anticoagulation with heparin with plans to bridge over to oral anticoagulation. His neurology was intact postoperatively and had no signs of systemic embolisation of the thrombus. Figure 3 reveals postsurgical specimen.

Patient was diagnosed with prostate cancer from the biopsy taken 2 days before the incidence and received treatment for the same.

Preventive strategies in future would include minimising complete cessation of anticoagulation especially for surgical procedures, working up for further haematological causes and treating underlying cancer.

Discussion

Presence of PFO in patient with pulmonary embolism is an independent predictor of death, systemic embolisation and having a complicated hospital course.¹ The complexity and heterogeneity of this patient subgroup come with unique challenges in management. Due to rarity, the options are mainly individualised and no guidelines exist to most cost effective diagnostic and treatment strategies.

Treatment can be surgical (thromboembolectomy), catheter-based by interventional radiology or conservative (which is systemic anticoagulation or thrombolysis). In their systematic literature review (1991–2015) for treatment of trapped thrombus in PFO that included 194 patients, Seo et al showed that surgery was associated with a lower overall incidence of post-treatment embolic events and a lower 60-day mortality. Interestingly thrombolysis was associated with a higher 60-day mortality compared with surgery especially in patients without haemodynamic compromise and cardiac arrest.² In their case series of surgical pulmonary embolectomy for massive pulmonary embolism, Dumantepe M et al showed that it is a safe procedure, with low mortality, improved postoperative right ventricular function and pulmonary pressure and good long term outcome.³ Catheter-directed thrombolysis in a patients with straddling thrombus might disrupt the clot in right atrium. Ultrasound-accelerated catheter-directed thrombolysis that delivers uniform radial ultrasound energy on top of continuous small doses of thrombolytic is another approach without major bleeding complications, but it is not without risks of clot fragmentation in this patient population.³

The treatment strategy should take into consideration individual parameters such as patient’s age, haemodynamic stability, bleeding risk and comorbidities. Overall, surgical thromboembolectomy with PFO closure is favoured over thrombolysis or anticoagulation alone.

Patient’s perspective.

I am currently back to work after being treated for prostate cancer. When in ICU, I remember doctors talking to me about significant clot in my heart and its risk of leaving me paralysed and other risks. I had no choice but to go for surgery. I now think that was the best decision.

Learning points.

• Straddling thrombus through patent foramen ovale has high mortality and morbidity.

• Echocardiographic screening for patent foramen ovale should be recommended in patients with massive or submassive pulmonary embolism.

• Multidisciplinary team approach between cardiology, cardiothoracic surgery, interventional radiology and intensive care team is important for favourable outcome.

• Surgical thromboembolectomy should be considered first, as it has less chances of systemic embolisation compared with thrombolytic therapy or anticoagulation alone.