PTMC involves a critical step , where one has to cross the IAS to reach the LA.The septal puncture remains somewhat a blind procedure in fluoroscopy .(Echo can still assist us. )
Stitch effect is a rare complication where the needle pierces the intrapericardial space from the right atrial side and re-enter the left atria .This wrong way entry into LA may not be recognised untill the sheath is withdrawn and a cardiac tamponade ensues after removal.
Where exactly the stitch occurs ? What are the anatomical planes ?
This usually happens in the superior aspects of IAS , abutting the roof of RA and LA . The alignment of IAS with reference to RA and LA is key a determinant.We know in mitral stenosis LA can outgrow the RA , bringing superior aspect of LA in a different plane with reference to IAS .The IAS puncture site may overshoot , enter the pericardial space and stitches the non IAS aspect of RA and LA together , of course still guiding us into LA through a false pericardial track (Which is not recognized )
Our understanding(mis ?) suggests at least four different stitches are possible
- IAS-Pericardial space -LA roof
- RA-Pericardial space -LA roof
Other complex tracts (Based on theoretical assumptions . Please note , in some of the fatal punctures the exact route was not identified by surgeons even under direct vision . )
3.RA-Pericardial space -Extra cardiac-Reenter LA
4.RA-IAS -Pericardial space-Extracardiac -Reenter LA ?
What are the possible bleeding sites in stitch effect ?
There can be two sites of active bleeding .One from RA exit point and other from LA entry point of needle.Extra-cardiac oozing can also occur if the needle has pierced the outer pericardium before entering LA.
- Recognition is the key. It requires extra anatomic acumen to diagnose the false track before we insert and withdraw the sheath.Echocardiography should be liberally used if you suspect a false track .
- Tamponade is to be drained promptly and emergency surgery is usually required if re-accumulation occurs.
- Closing the puncture site with devices has been successfully attempted in few patients .A small ASD device (or a Plug ? ) is expected to close the site of puncture . Since the anatomy can be complex ,one may need to close with two devices , one on LA side and other one RA side .The radial force that closes the tear and long term retention of these device are not known .