Lasted edited: 15/4/2018
Learning objectives
- Appropriate settings to look for Paradoxical Embolism
- Causes of Paradoxical Embolism
- Investigations of Paradoxical Embolism
- Treatment options
Aetiology
The pulmonary circulation provides a large filter for any small thrombi returning from the systemic circulation. A small microthrombus to the lungs is probably insignificant but if the pulmonary circulation can be bypassed and shunted then there is a risk of thrombi entering the systemic arterial circulation. This can happen when there are areas allowing right to left shunting in the heart such as a patent foramen ovale or Atrial septal defect or Ventricular septal defect or other form of congenital heart disease. However clots bypassing the lungs can be seen in those with pulmonary arteriovenous malformations.
Paradoxical Embolic Stroke = DVT + Right to left shunt
Causes
| Cause | Comments |
|---|---|
| PFO | Most are entirely innocent and seen in 25% of population but 50% with cryptogenic stroke. Closed by catheter if felt to be causative |
| ASD | Flow will usually go Left to right but here can be reversal.Get Echo. Bubble study. May be surgically closed |
| VSD | Flow will usually go Left to right but here can be reversal with Eisenmenger's syndrome. Get Echo. Bubble study. May be surgically closed |
| Other Congenital heart disease with R/L shunt | Flow will usually go Left to right but here can be reversal with Eisenmenger's syndrome. Get Echo. Bubble study. May be surgically closed |
| Pulmonary AVM | A lesion may be seen on CXR. Needs CTPA. Bubble study will show bubbles in LA after several cardiac cycles. Can be considered for occlusion by interventional radiologists |
Investigations
- FBC, U&E, ESR, U&E, LFTs
- ECG: AF, RBBB + Axis deviation can suggest ASD
- CXR: may show a lung AVM
- CT/MRI: Multiple territory infarcts
- CTPA: may show pulmonary AVM
- Echo and Bubble study: shows bubbles cross interatrial septum
- Transoesophageal echo
Evidence Against Repeated Paradoxical embolism
- Presence of AF or PAF or other more probable cause
- Stereotypical (identical) Strokes or TIA symptoms
- Lack of multiterritory disease on MRI
Evidence For Repeated Paradoxical embolism
- Multiple territory infarcts
- Procoagulant condition or Evidence of a DVT at the time - Doppler USS or at least a raised Dimer
- Evidence of a shunt with Right to left flow
- Sudden onset
- Clear history of a neurological deficit
Management
- Prevent DVTs +/- Occlude the shunt R/L shunt
- See Patent Foramen Ovale
| Note: The plan is to keep the website free through donations and advertisers that do not present any conflicts of interest. I am keen to advertise courses and conferences. If you have found the site useful or have any constructive comments please write to me at drokane (at) gmail.com. I keep a list of patrons to whom I am indebted who have contributed. If you would like to advertise a course or conference then please contact me directly for costs and to discuss a sponsored link from this site. |