Transseptal Access Research Articles

Radiofrequency current delivery via transseptal needle to facilitate septal puncture

Transseptal catheterization is a technique that has been used since the late 1950s to gain percutaneous access to the left atrium (LA). 1 De Ponti R. Zardini M. Stori C. Longobardi M. Salerno-Uriarte J.A. Trans-septal catheterization for radiofrequency catheter ablation of cardiac arrhythmias. Eur Heart J. 1998; 19: 943-950 Crossref PubMed Scopus (82) Google Scholar With the advent of catheter-based approaches to intervene on diseased mitral valves and cardiac arrhythmias, the need for access to the LA has increased. At present, multiple modalities including traditional fluoroscopic guidance and intracardiac pressure monitoring with either transesophageal echocardiography or intracardiac echocardiography (ICE) are available to assist transseptal access. 2 Daoud E.G. Transseptal catheterization. Heart Rhythm. 2005; 2: 212-214 Abstract Full Text Full Text PDF PubMed Scopus (25) Google Scholar Despite increased operator experience and better visualization when performing transseptal catheterization, there are several clinical settings in which crossing the septum is very difficult or impossible. 3 Marcus G.M. Ren X. Tseng Z.H. Badhwar N. Lee B.K. Lee R.J. Foster E. Olgin J.E. Repeat transseptal catheterization after ablation for atrial fibrillation. J Cardiovasc Electrophysiol. 2007; 18: 55-59 Crossref PubMed Scopus (60) Google Scholar These include patients undergoing repeat transseptal access, patients with cardiac surgical repair involving the interatrial septum, or patients with anatomic variants including lipomatous or aneurysmal interatrial septal deformity. To overcome these challenges, techniques that use active methods such as dedicated radiofrequency (RF) systems to perforate the septum and other cardiac structures have been developed and used clinically. 4 Justino H. Benson L.N. Nykanen D.G. Transcatheter creation of an atrial septal defect using radiofrequency perforation. Catheter Cardiovasc Interv. 2001; 54: 83-87 Crossref PubMed Scopus (48) Google Scholar , 5 Benson L.N. Nykanen D. Collison A. Radiofrequency perforation in the treatment of congenital heart disease. Catheter Cardiovasc Interv. 2002; 56: 72-82 Crossref PubMed Scopus (31) Google Scholar , 6 Pedra C.A. Filho R.M. Arrieta R.S. Tellez R. Fontes V.F. Recanalization of a discrete atretic right pulmonary artery segment with a new radiofrequency system. Catheter Cardiovasc Interv. 2003; 60: 82-87 Crossref PubMed Scopus (8) Google Scholar

Interventional Atrial Septal Defect Closure Using a Totally Bioresorbable Occluder Matrix: Development and Preclinical Evaluation of the BioSTAR Device

We sought to test the hypothesis that interventional atrial septal defect (ASD) closure can be performed safely and effectively using a bioresorbable occluder matrix. The ideal septal occluder scaffold should promote the healthiest and most complete healing response while eventually facilitating the full resorption of the material and leaving "native" tissue behind, thus minimizing the potential for future complications from chronic foreign body and maintaining the possibility for later unobstructed transseptal access to the left atrium. The STARFlex occluders (NMT Medical Inc., Boston, Massachusetts) were modified by substituting the conventional polyester fabric for a bioengineered, acellular type-I collagen matrix derived from porcine submucosa with a heparin-coated surface (BioSTAR occluder, NMT Medical Inc.). Comparative transcatheter closure of ASDs was performed in young sheep (n = 36). Gross pathology and histopathology were obtained after follow-up periods ranging from 7 days to 2 years. The STARFlex (control) devices were encapsulated time-dependently by ingrown fibrous tissue. Histology showed a mild but chronically persisting foreign body reaction. By contrast, BioSTAR devices exhibited a mild-to-moderate transient cellular immune response. Heparin coating of the BioSTAR surface improved the biocompatibility of the device by reducing surface thrombogencity. A remodeling process of the collagen scaffold, starting after 30 days in vivo, resulted in the full replacement of the matrix by host tissue after 2 years of follow-up. The BioSTAR device is the first septal occluder with a totally bioresorbable matrix that is fully replaced by host tissue during the healing process. The promising results of this study support testing of the BioSTAR device in clinical trials.

Transatrial septal catheterization using a new radiofrequency probe

Percutaneous therapeutic techniques requiring transseptal catheterization have increased in recent years. The traditional and current method for transseptal catheterization involves needle puncture, an effective but complicated technique, which is associated with a small but significant incidence of both perforation of structures adjacent to the atrial septum and pericardial tamponade. Enhanced imaging has reduced but not eliminated the risk of these complications. We have used an alternative method for transseptal access to the left atrium, which employs a novel radiofrequency catheter system. In this report, we describe the system and its use in our initial series of patients.

Radiofrequency perforation and conventional needle percutaneous transseptal left heart access: Pathological features

Perforating radiofrequency (PRF) energy has been used to obtain percutaneous transseptal left heart access. Contrary to ablative radiofrequency (RF), myocardial tissue responses to PRF thermal injury are incompletely defined. In this study, a newly developed RF catheter system for transseptal left atrial entry was compared with conventional needle puncture. Of 15 piglets having transfemoral cardiac catheterization, 12 had transseptal procedures. Needle punctures (NP) and PRF were followed by acute (1 hr; 3 NP, 3 PRF) and chronic necropsy (1 month; 3 NP, 3 PRF). The remaining three piglets had intentional RF aortic perforation through the atrial roof with necropsy at 1 month. Gross and histopathological effects were examined. Acutely, the gross RF lesion was similar to needle puncture. Histologically, the RF lesions had minimal mural thrombus, an inner zone of thermal injury characterized by grayish cytoplasmic staining (elastic trichrome), and a bubbly transformation of the cytoplasm in innermost cardiomyocytes, partial persistence of cross-striations, and an acute inflammatory reaction. The outer extent of the lesion (< 1 mm) was defined by a halo of contraction band necrosis similar to needle puncture. Acute NP injury showed comparable depth and extent of myocyte necrosis (principally contraction bands) with adjacent tissue hemorrhage and edema. At 1 month, a well-developed densely collagenous scar was present in both aortic and transseptal PRF lesions. The extent of acute RF injury is similar to that seen in conventional NP, but the characteristics of tissue insult are different. Both show well-developed healing at 1 month.

Pulmonary Vein Antrum Isolation:

Several techniques are used for AF ablation, but no general consensus exists as to which technique is the most effective. At our center, we have developed a technique for isolating the pulmonary veins (PVs) at their antrum. The technique is guided by intracardiac echocardiography (ICE) and mapping with a circular (Lasso) catheter. Our technique was developed based on four crucial principles: 1. Precisely identifying the true border of the PV antrum. 2. Electrically isolating all of the PVs at the level of the antrum. 3. Avoiding risk of PV stenosis by ablating outside of the antrum. 4. Minimizing risk of other complications, such as perforation and stroke, by direct visualization during transseptal access and radiofrequency (RF) ablation.

Ablation of focal atrial fibrillation.

In the past decades management of atrial fibrillation (AF) has been based mainly on drug therapy. New insights into the pathophysiology of AF initiation and maintenance have provided the background for the design of catheter based procedures. The crucial role of the pulmonary veins (PVs) as triggers of AF paved the way for successful mapping and ablation. Electrical isolation of all PVs using the circular mapping approach has been shown to be an effective procedure, with reported success rates around 70 to 80% in most series. Intracardiac echocardiography is a very helpful adjunctive tool to facilitate correct positioning of the circular catheter at the PV-left atrial junction, as well as to monitor energy delivery and assist transseptal left atrial access. PV stenosis is a potential serious complication, occurring in around 2% of cases. It presents mainly with respiratory symptoms, although it is frequently asymptomatic. Spiral computed tomography is a reliable non-invasive method for imaging the PVs and can be used to screen patients for PV stenosis after radiofrequency ablation. In symptomatic patients, PV dilatation and stenting is the preferred treatment approach. The possibility of curing AF represents a major breakthrough in invasive cardiac electrophysiology. Isolation of all PVs is a very solid endpoint for successful ablation and should be pursued in all patients. It seems to be associated with high success rates over long term follow-up. Future refinements in catheter technology should provide simpler and faster procedures and render catheter ablation of AF more widespread and accepted.