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ASD DEVICE CLOSURE
Atrial Septal Defect
Defect in the interatrial septum allowing pulmonary venous return from left atrium to pass directly to the right atrium. Types ASD Type Location Associations Ostium Secundum (75-85%) - Defect in the region of fossa ovalis.
- Maybe single or multiple (fenestrated atrial septum) - Partial anomalous pulmonary venous return - Pulmonary Stenosis - VSD - Pulmonary artery branch stenosis - Persistent Left SVC - MV Prolapse or regurgitation Ostium Primum (10-15%) - Situated in the lower portion of the atrial septum and overlies the mitral and tricuspid valve.
- Ostium primum defects with clefts in the anterior mitral and septal tricuspid valve leaflets
- Discrete subaortic stenosis
- Small VSD Sinus Venosus (5-10%) - Most commonly located at the entry of SVC into the RA (SVC Type)
- Rarely at the entry of IVC into the RA (IVC Type) - SVC Type: Associated with anomalous drainage of the right upper pulmonary vein (into the RA) - IVC Type: Associated with anomalous drainage of the right lung into the IVC (Scimitar Syndrome) Coronary Sinus Defects (1%) - There is a defect in the roof of CS, resulting in direct communication with the LA.
- Types: Complete unroofing of the CS Partial unroofing of the CS - Persistent Left SVC - Partial and total anomalous pulmonary venous return Morphology
- Increase L→R shunt
LV Compliance ↓ LAP ↑ Pathophysiology ASD Physiology
- RV / RA dilation
- Atrial arrhythmias: Incidence increase with age and defect size 11% in patients with Qp:Qs <2:1 vs 38% in pts with shunt >3:
- Right heart failure
- Pulmonary Hypertension 5-10% of untreated ASD Incidence increases with age Female > male More common in pts living at higher altitude Pathophysiology of a large ASD. Dotted lines indicate the chamber enlargement. Number of arrows demonstrate amount of blood flow. RA = right atrium; RV = right ventricle; LA = left atrium; LV = left ventricle.
Closure Devices
FDA-Approved devices:
- Amplatzer Septal Occluder (AGA)
- Amplatzer Cribriform Septal Occluder (AGA)
- HELEX Septal Occluder (Gore) Other devices (current and historical):
- Figulla ASD Occluder (Occlutech)
- AtriaSept ASD Device (CARDIA)
- BioSTAR - Bioabsorbable Septal Repair Implant (NMT)
- Sideris Buttoned Device
- Transcatheter Patch
- DAS Angel Wings
- ASDOS
DEVICE DESIGN & SIZE ADVANTAGES DISADVANTAGES
- AMPLATZER Septal Occluder A: Device Size/ Waist Diameter (mm) B: Waist Length (mm) C: RA Disc Diameter (mm) D: LA Disc Diameter (mm) - Self-expandable - Double disc - Nitinol wire mesh (0.004" - 0.008") - Polyester (Dacron) fabric fills the waist and discs. - Sizes: Waist Diameter: 4-40 mm Waist Length: 3-4 mm - LA disc exceeds waist by 12-16 mm. - RA disc exceeds waist by 8-10 mm. - Largely used worldwide - Very easy to use - Retrievable until release - All sizes up to 40mm are available. - Prevalence of residual defect is low. - Erosion and tamponade (very rare, 0.1%) - Not for use in those with nickel allergy.
- GORE HELEX Septal Occluder - Two discs formed by one - Preloaded in catheter - Challenging
continuous wire in the shape of a spiral.
- Sizes: 15- 35 mm
- PTFE patch attached to the wire. - Soft and atraumatic - Sheath is not required, hence the reduced risk of air embolism. - Safety chord - retrievable at any stage of the procedure, even after release. - Metal part of this device is mostly covered so no thrombus formation/erosion experienced. visualization by TTE.
- Device embolizations, more frequent than with other devices
- Residual shunts more frequent (but no embolic events)
- Wire fractures – rare
- Defects up to 20 – 22 mm
- CARDIOSEAL/ STARFLEX Septal Repair Implant
- Modified version of the Clamshell device.
- Two square Dacron patches mounted between four steel arms to facilitate device centering.
- STARFLEX has additional microsprings attached to device arms.
- Easy to use (pre- mounted version)
- Device arms are flexible and can bend independently from each other.
- Difficult to retrieve when right disc is opened.
- Wire fractures (in larger defects and devices)
- Thrombus formation
- New onset of atrial fibrillation
- FIGULLA FLEX ASD AND PFO Occluders - Sizes: Available from 6- 40 mm size.
- Retrievable and safe
- System allows a tilt of 45 ◦ using a biopsy forceps delivery method. Therefore, much better when used in challenging cases.
- The new Occlutech connector means is without a traditional steel hub. That means an important minimizing amount material implanted.
- The new deliver system allows a tilt upto 45 ◦ giving perfect placement prior to release.
- Flexible
- Excellent for large defects in adults.
- BIOTREK BIOABSORBABLE Septal Repair - Design: Confirms to wide range of defect morphologies. Easy to use - repositionable and radiopaque
- Polymer: Novel bioabsorbable polymer (P4HB) It gets absorbed as a non-inflammatory natural metabolite. - Biologically produced: Isolated from bacteria modified by rDNA technology. - Implant/Tissue Interface: Incorporates biological response modifiers to regulate thromboresistance and endothelialization.
- More flexible and less inflammatory than currently available bioabsorbables. - Newest development Status: currently in pre-clinical studies. Therefore, it is not in practice.
- BIOSTAR BIOABSORABLE TISSUE- EGINEERED COLLAGEN MATRIX Implant - STARFlex® self— centering - Easy to use - Improved
- Cardioseal framework
- Bioresorbable collagen derived from the submucosa derived from the intestine “biological” edge-to- edge seal matrix gradually remodeled and replaced with host tissue.
- Rapid Endothelialization: High early closure rate Reduced risk of thrombosis
- Regenerative of native septum: Improved potential for LA access later in life
- LIFETECH /CERA Devices - Sizes: 6-40 mm
- Need 8 Fr to 14 Fr sheaths.
- Material: Nitinol, Polyester, Pure Stainless Steel tip, PTFE membrane
- Available with a kink-resistant delivery Sheath
- Lab investigations: CBC Renal Function Test (Blood Urea Nitrogen, Serum Creatinine) PTT-INR HIV, HBsAg, HCV
- Deciding which anticoagulant to be used.
- Start IV line and administer anaesthesia.
- Start aspirin (5mg/kg/day for 4 days prior) +/- Clopidogrel.
- Making sure that antibiotics are on-call. Right heart pressure and saturation assessment +/- coronary angiogram. Assessing the LA via the defect. Transoesophageal or Intracardiac echo assessment of septum. +/- Angiography of the defect. Compliant balloon to assess defect size and morphology. Proper implant and size selection. Procedure: Delivery sheath in LA/upper pulmonary vein. Left atrial side opened. Device pulled back to contact left atrial septum. Right atrial side opened. Device release only after echo and fluoroscopic confirmation of position. Post – procedure: Extubation on table. Monitoring the vitals in the recovery room for 6 hours. ECG after transferring to the recovery room. Continue IV antibiotics – 2 more doses. Repeat ECG and TTE on day 2 of procedure before discharge. Post- procedural Follow up Follow-up with clinical evaluation, ECG and TTE at 1 week, 1 month, 6 months and 1 year and yearly for 2 years. Follow-up and imaging every 3-5 years afterwards. Infective endocarditis prophylaxis for 6 months post procedure.
Complications
Bleeding can occur due to use of aspirin, heparin and post procedure Clopidogrel. This may include GI or intercranial bleeding that may require transfusion. Other complications include prolonged procedural time, suboptimal deployment position with moderate or severe residual shunt. Device misalignment/embolization Device erosion of atrial wall or aorta (can result in pericardial effusion or tamponade) Device impingement on adjacent structures AV valve, Coronary sinus, SVC, Pulmonary veins, Aorta Infection including endocarditis Thromboembolic Complication (could be catheter related) Allergic reaction Valvular regurgitation
Air Embolism Transient ischemia shock or stroke LA disc deformation Atrial Arrhythmias can occur in 2-4% of the cases. The arrhythmias are due to the foreign body inflammatory response and usually resolved with medical therapy. AV conduction block and on occasion, complete heart block may be seen and is treated with dexamethasone therapy, but may require permanent pacemakers in some cases.
Contraindications
Sinus venosus, coronary sinus or primum ASD Extensive congenital cardiac anomaly Known sepsis within one month prior to implantation or any untreated systemic infection prior to device placement. Bleeding disorder, untreated ulcer or any other contraindications to aspirin therapy. Resting Pulmonary Hypertension Insufficient septal rims Pregnancy Demonstrated intracardiac thrombi on echo. Any patient whose size or condition would cause to be a poor candidate for cardiac catheterization.
Advantages
It is safe and cost-effective than surgery. Successful implantation rates, more than 96% Fewer complications: Major <1% Shortened hospitalization Avoidance of pain and residual thoracotomy scars Reduced need for blood products
Disadvantages
Higher rate of small residual leak.
Membranous
- Small
- Located at base, between inlet and outlet
- The septal leaflet of the TV divides the membranous into 2 components: pars atrioventricularis and pars interventricularis.
- Perimembranous - Extends to adjacent Muscular septum is a non-planar structure that can be divided into: inlet, trabecular and outlet Inlet
- Has no muscular rim between the defect and the Atrioventricular valve annulus.
- AV valve to chordae attachments. Trabecular
- Location classification: Anterior/Marginal (anterior to septal band) Midmuscular/Central (posterior to septal band) Outlet (conal, infundibular)
- Infundibular septum separates RVOT and LVOT.
- On the right side, it is bordered by the line from the membranous septum to the papillary muscle of the conus inferiorly and the semilunar valves superiorly. Types Perimembranous (70-80%)
- Also called conoventricular defects.
- This is an opening in the upper section of the ventricular septum, near the AV and TV.
- Margins include membranous septum or remnant
- May have extensions into inlet, outlet and trabecular septum.
- Postero- inferior margin very close to antero-septal commissure of the TV.
- Can extend upto non-coronary cusp of AV Muscular (5-20%)
- Also known as trabecular VSD
- This is an opening in the muscular portion of the lower section of the ventricular septum.
- Muscle tissue all around the defect.
- According to their location, they may be either anterior, in the inlet septum, mid-muscular or apical. Atrioventricular Canal (5-8%)
- Also known as Inlet VSD.
- The posterior rim of the defect runs along the septal leaflet of the TV to the central fibrous body and the AML (which may have as cleft in association).
- No intervening muscle between VSD and the TV.
- Conduction system is affected. Subarterial (5-10%)
- Also called outlet, conal, subpulmonary and supracristal VSD.
- Occur due to mal-development of bulbotruncal system.
- Located within infundibular portion of RVOT.
- Superior margin: no muscular tissue
- Inferior margin: defect is muscular
- Can extend upto right or sometimes non-coronary cusps of the AV. Pathophysiology
Perimembranous VSD with more than mild AR + recurrent endocarditis. Subarterial VSD Children without irreversible Pulmonary Hypertension:
- Significant symptoms failing to respond to medication.
- Elective surgery (performed between 3~9 m/o)
Intervention
Surgery direct: suture or with a patch
- Single- stage closure: Large defect, CHF s/s, failure to thrive
- Perimembranous and muscular defects + normal PAP + no s/s →delayed OP upto 1 year or more
- Patient >10y/o with a small defect with a small defect (QP/QS > 1.5; normal PAP) → controversial. Device Closure
- Trabecular VSDs have proven more amenable.
- Perimembranous VSDs is technically more challenging.
Closure Devices
DEVICE DESIGN & SIZE ADVANTAGES DISADVANTAGES
1. AMPLATZER MUSCULAR VSD
Device Device Size (Waist = A) Right Ventricular Disc (B) Left Ventricular Disc (C) Length of Waist (D)
- Symmetric
- Waist Length: 7mm
- Discs exceed waist by 1mm, i.e., disc size: 8 mm.
- Incorporated with Dacron fabric
- Sizes: 4-18 mm
- Waist is broad
- Used upto 16-17 mm
- Even in those with PHT - Not designed for PMVSD closure - Larger sheath - Encroachment on the LVOT and aortic valve - TV mechanism
2. AMPLATZER ASYMMETRIC VSD
Occluder
- Very short (1.5 mm) connecting waist to minimize contact with the TV.
- In its latest design the left sided disk extends 5mm towards the apex (with a platinum marker) to lean firmly on the muscular septum and only 0.5 mm towards the aorta to avoid contact with the AV.
- The right sided disk is 4 mm larger than the waist.
- The prosthesis is filled with Dacron fabric to facilitate thrombosis.
- Prostheses are available in sizes ranging from 4– mm at increments of 2 mm.
- AMPLATZER PERIMEMBRANOUS VSD Devices Device Size (Waist = A) Right Ventricular Disc (B) Left Ventricular Disc (C)
- Allows for placement that avoids interference with the aortic or atrioventricular valves.
- Devices range from 4 to 18 mm, in single mm increments
- LV disk is 6 mm larger, RV disc is 4 mm larger than waist.
- Specifically designed for PMVSDs
- Asymmetric design is ideal for preventing AV injury
- For VSD size of upto 16 mm
- Protrusion into the LVOT
- Interference with aortic and tricuspid valve mechanisms.
- Complete Heart Block
Arteriovenous wire loop Long transvenous sheath Device implantation
Complications
Major complications: Complete AV block Aortic-/ Tricuspid valve dysfunction
Malposition/embolization of device Residual defect (severe) Severe hemolysis Minor complications: Transient arrythmias Residual defect (small) Transient hemolysis Inguinal hematoma and fistula
Contraindications
Patients with defects less than 4 mm distance from the semilunar (aortic and pulmonary) and atrioventricular valves (mitral and tricuspid). Patients with severely increased pulmonary vascular resistance above 7 woods units and a right-to-left shunt and documented irreversible pulmonary vascular disease. Patients with perimembranous (close to the aortic valve) VSD. Post-infarction VSD. Patients with sepsis (local/generalized)
