Pulmonary Embolism – Right ventricular thrombus

Images Nick Stewart text Genevieve Carbonatto

A 22 year old patient presents to the Emergency Department with calf pain. On further questioning she has had  a presyncopal event the day of presentation and complains of shortness of breath. She has recently been put on tranexamic acid for heavy menstrual bleeding. She is also on the oral contraceptive.

On examination she is tachycardic at 120/min, her BP is 110/90, her saturations 96% on room air, her chest is clear on auscultation, her left calf is swollen. A point of care ultrasound is performed to look for a pulmonary embolism.

The PLAX view shows a thrombus in the right ventricle, and a  large RV

The PSAX view better demonstrates flattening of the IVS causing a D shaped left ventricle due to RV pressure overload. A large mobile thrombus is again seen within the large RV.

The 4 chamber view shows that there are 2 thrombi within the RV. The RV is again seen to be enlarged. It is bigger than the LV and the IVS is flattened indicating high RV pressures. Looking carefully at the apex of the LV, right mid ventricular wall hypokinesis causing an “indentation” of the free RV wall at the apex is visualised. This is MConnell’s sign.

 

She is hemodynamically stable and an immediate CTPA is organised which shows a saddle pulmonary embolus. She is anticoagulated. Her troponin is 30

Shortly afterwards her BP drops to  90mmHg systolic , and she becomes more tachycardic. Angiojet thrombolysis of her pulmonary arteries is performed with  normalisation of both her BP and HR.

Discussion:

Thrombi in the right ventricle, associated with pulmonary embolism, has a prevalence of 4%. The prognosis  of patients with right heart thrombi is related to the haemodynamic effects of the pulmonary embolism, not the presence of right heart thrombi (2)

Shock (3,4) is an independent predictor of mortality in patients with right heart thrombi. Clot motility is not a predictor of mortality.

Treatment:

Risk stratification is the first step in treating patients with pulmonary embolism.(5)

1. LOW RISK : No imaging evidence of RVS, normal cardiac biomarkers. May be asymptomatic
2. INTERMEDIATE LOW RISK : Normotensive with either 1. imaging evidence of RVS, 2. elevated cardiac biomarkers
3. INTERMEDIATE _HIGH RISK : Normotensive with both 1. imaging evidence of RVS and 2. elevated cardiac markers
4. HIGH RISK : cardiac arrest, cardiogenic shock, paradoxical bradycardia, vasopressor requirements, hypotension , acute respiratory failure, ventricular tachyarrhythmias

• Low risk patients, such as patients with no imaging evidence of right ventricular strain, normal cardiac markers and who are asymptomatic can be treated with oral anticoagulation alone (NOAC).
• Patients with very high risk pulmonary embolism presenting with cardiac arrest, cardiogenic shock, paradoxical bradycardia or who require vasopressors should be considered for systemic thrombolysis or embolectomy.
• Intermediate risk patients with evidence of right heart strain on ECHO and elevated cardiac markers pose a therapeutic dilemma as the risks of significant bleeding from systemic thrombolysis is not insignificant with this therapeutic option.
• Hybrid solutions are now available; catheter directed thrombolysis (as was used in this case), ultrasound assisted thrombolysis (which uses ultrasound through a catheter to break up filaments of clot in association with with low dose targeted thrombolytics through another catheter), percutaneous mechanical interventions involving disruption or removal of the clot  and surgical pulmonary embolectomy.
• Caval filters have been used as an adjunct to halt large thrombi from passing through them into the pulmonary veins.
• ECMO has been used successfully as haemodynamic support while embolectomy is performed .

A comparison of treatment options  for patients with pulmonary embolism are included in the table below.

 

Treatment	Administered by	Time to initiate	Major benefits	Major detriments
Systemic anticoagulation	All practitioners	minutes	Ease, expense	Treatment failure Time to effect Limited data on oral anticoagulants in intermediate – risk PE
Systemic thrombolysis	All practitioners	minutes	Rapid initiation of reperfusion without specialized equipment	Intracranial and other major bleeds
Catheter induced thrombolysis	Interventionalists	Minutes to hours	Hybrid mechanical and pharmacological approach	Lack of randomized data. Specialized expertise required
Ultrasound assisted catheter  directed thrombolysis	Interventionalists	Minutes to hours	En bloc removal of thrombi	Specialized expertise required, large bore access. May not reach distal thrombi
Surgical pulmonary embolectomy	Cardiothoracic surgeons	Minutes to hours	Comprehensive proximal thrombectomy	Sternotomy Specialised surgical expertise
Caval filters	Interventionalists	Minutes to hours	Aim to prevent further thrombus migration, avoid anticoagulation	Multiple late mechanical complications, because of failures to monitor and to retrieve the filter

There is still a lack of consensus and guidelines regarding the management of right sided thrombi in the context of pulmonary embolism. It is thought that these thrombi are simply thrombi “in transit”. They are not included in the risk stratification but are often considered for thrombolysis or percutaneous or surgical embolectomy.

Data showing significant cumulative  risk of major bleeding (13%) including intracranial  bleeding (2% rate)  with thrombolysis  indicate that thrombolysis should be used only in haemodynamically  unstable patients irrespective of whether right heart thrombi are present or not. (4)

References

1. Right Heart Thrombi: Patient Outcomes by Treatment Modality and Predictors of Mortality: A Pooled Analysis. J Intensive Care Med. 2018 Oct 29
2. Outcome of patients with right heart thrombi: the Right Heart Thrombi ,Marcin Koć et al European Respiratory Journal 2016 47
3.  The ESC Textbook of Intensive and Acute Cardiovascular Care (2 ed.)Edited by Marco Tubaro, Pascal Vranckx, Susanna Price,and Christiaan Vrints
4.  Management of Pulmonary Embolism An Update Stavros V. Konstantinides, Stefano Barco, Mareike Lankeit and Guy Meyer Journal of the American College of Cardiology  Volume 67, Issue 8, March 2016 DOI: 10.1016/j.jacc.2015.11.061
5. Interventional Treatment of Pulmonary Embolism David M. Dudzinski, MD, JD; Jay Giri, MD, MPH; Kenneth Rosenfield, MD, MHCDS Circ Cardiovasc Interv. 2017;10:e004345.