Transseptal puncture - Review of anatomy, techniques, complications and challenges.

In recent years, the transseptal puncture approach has enabled passage of increasingly large and complex devices into the left atrium. Traditional tools remain effective in creating and dilating the initial puncture, with an acceptable safety profile. Even for skilled operators, the procedure is technically demanding and requires sound understanding of atrial anatomy. Intracardiac echocardiography is useful in cases of previous septal repair, poorly defined fossa ovalis anatomy or when considering patent foramen ovale portal crossing. Iatrogenic atrial septal defect (iASD) is the most commonly encountered long-term complication and there is increasing evidence that larger devices are leading to symptomatic defects. The size of the sheath crossing the septum is the strongest predictor of iASD formation but other factors such as longer procedure times, significant catheter manipulation and high pulmonary pressures also contribute. Transcatheter mitral valve repair involves the use of large 22 Fr catheters which carry alarmingly high rates of defect persistence with precipitation of symptoms and possible influence on mortality. Long-term follow up data, particularly beyond the 12-month period are lacking and resultantly, evidence to guide management is sparse. Refinements of conventional instruments, as well as innovations to puncture the septum without mechanical pressure, herald a progressively safer future for the transseptal technique.