Introduction to Minimally Invasive Modalities
- Minimally invasive management encompasses transcatheter interventions, fetal cardiac procedures, and hybrid approaches.
- Offers definitive or palliative treatment with reduced surgical trauma, avoidance of cardiopulmonary bypass (CPB), and rapid recovery.
- High-technology hybrid catheterization laboratories combine fluoroscopic imaging with operating suites for complex lesion management.
Fetal Cardiac Interventions (FCI)
- Goal involves altering natural history in utero to improve postnatal morbidity and mortality.
- Minimally invasive approach utilizes ultrasound-guided 18/19-gauge cannula puncture through maternal abdomen, uterine wall, and fetal chest wall directly into target cardiac chamber.
| Fetal Lesion | Intervention | Procedural Technique & Hemodynamic Goal |
|---|---|---|
| Severe Aortic Stenosis (AS) | Fetal Aortic Valvuloplasty | Balloon advanced across aortic annulus; inflated 100-120% of annulus size. Goal: Prevent evolving hypoplastic left heart syndrome (HLHS) and promote biventricular circulation. |
| Pulmonary Atresia/Critical PS | Fetal Pulmonary Valvuloplasty | Performed for intact ventricular septum to prevent evolving hypoplastic right heart syndrome (HRHS). |
| HLHS with Restrictive Atrial Septum | Fetal Atrial Septoplasty | Balloon dilation or septal stent placement for established HLHS with intact/restrictive atrial septum. Goal: Improve neonatal stability. |
Transcatheter Septal Defect Closures
Atrial Septal Defect (ASD) & Patent Foramen Ovale (PFO)
- Standard therapy for secundum ASDs and PFOs with sufficient tissue margins.
- Procedure guided by intracardiac echocardiography (ICE) or 3D transesophageal echocardiography (TEE).
- Femoral vein access standard; transhepatic approach preferred if bilateral femoral venous occlusion exists.
- Superior sinus venosus ASDs may utilize covered stents (chimney technique).
Ventricular Septal Defect (VSD)
- Device closure standard for muscular and perimembranous VSDs.
- Approaches include antegrade (venous) or retrograde (arterial) delivery systems.
- Membranous VSD closure carries small risk of complete heart block.
Patent Ductus Arteriosus (PDA)
- Closure indicated to treat heart failure and prevent pulmonary vascular disease or endarteritis.
- Small PDAs managed with intravascular coils.
- Moderate-to-large PDAs managed with umbrella devices, vascular plugs (e.g., Nit-Occlud).
- Stenting of PDA serves as alternative to surgical Blalock-Taussig shunt in duct-dependent pulmonary circulation.
Transcatheter Valvular Interventions
| Target Valve | Pathophysiology | Catheter Intervention | Clinical Notes & Outcomes |
|---|---|---|---|
| Pulmonary Valve | Congenital Pulmonary Stenosis | Balloon Pulmonary Valvotomy | First-line treatment of choice. High procedural success replacing open valvotomy. |
| Pulmonary Valve | RVOT dysfunction (stenosis/regurgitation) | Transcatheter Pulmonary Valve (TPV) Replacement | Devices include Melody (bovine jugular vein in stent), Sapien, Harmony, and Alterra prestent. Avoids redo sternotomy. |
| Aortic Valve | Congenital Aortic Stenosis | Balloon Aortic Valvuloplasty | First-line therapy in neonates/children. High recurrence of stenosis and iatrogenic aortic regurgitation risk. |
| Aortic Valve | Degenerative / Severe AS | Transcatheter Aortic Valve Replacement (TAVR) | Increasingly utilized in older adult CHD patients with high surgical risk. |
| Mitral Valve | Rheumatic Mitral Stenosis | Balloon Mitral Valvuloplasty (PMBC) | Inoue balloon technique used. Highly successful for fused commissures. Contraindicated for significant regurgitation or LA thrombus. |
| Mitral Valve | Mitral Regurgitation | MitraClip | Catheter-delivered clip creates double-orifice valve to reduce insufficiency; investigational in pediatrics. |
| Tricuspid Valve | Degenerated Bioprosthesis | Transcatheter Valve-in-Valve (TVIV) Implantation | Minimally invasive treatment for failing surgical valves (e.g., in Ebstein anomaly). Excellent hemodynamic outcomes. |
Vascular Transcatheter Interventions
Coarctation of Aorta (CoA)
- Balloon angioplasty with or without stent placement.
- Preferred intervention in older children and adults.
- Neonates optimally managed with surgery due to high risk of recurrence, arterial aneurysm, and dissection with balloon therapies.
Pulmonary Artery (PA) Stenosis
- Managed with balloon dilation and stent implantation.
- Cutting balloon angioplasty utilized for highly challenging, small-vessel PA stenoses and in-stent restenosis.
- Major aortopulmonary collateral arteries (MAPCAs) in Tetralogy of Fallot/Pulmonary Atresia amenable to transcatheter balloon/stent dilation or coil occlusion.
Systemic Venous Stenosis & Thrombus
- Superior Vena Cava (SVC) obstruction (e.g., post-Mustard/Senning or heart transplantation) managed with stent implantation.
- Transcatheter thrombus management utilizes mechanical thrombectomy, balloon angioplasty, or acoustic pulse thrombolysis (EkoSonic Endovascular System).
Miscellaneous Interventions
- Coronary Artery Fistula: Transcatheter coil or device closure at distal orifice. Treatment of choice for symptomatic/large fistulas to prevent steal phenomenon or volume overload.
- Paravalvular Leaks: Device occlusion using vascular plugs (e.g., Amplatzer) under 3D TEE and fluoroscopic guidance. Success rates 70-90%.
- Balloon Atrial Septostomy (Rashkind): Creation of atrial communication in D-TGA or HLHS with restrictive atrial septum to improve mixing.
Hybrid Procedures
Hybrid therapies involve multidisciplinary collaboration between surgeons and interventional cardiologists, combining open and catheter-based techniques in a single setting to reduce CPB exposure and procedural trauma.
Stage 1 Palliation for HLHS
- Bilateral pulmonary artery banding, transcatheter stent insertion into ductus arteriosus, and balloon atrial septostomy.
- Avoids neonatal CPB exposure in high-risk patients with severe instability.
- Requires comprehensive Stage 2 reconstruction subsequently.
Perventricular VSD Closure
- Indicated for muscular VSDs in infants <5 kg where percutaneous delivery systems are too large for fragile peripheral vessels.
- Access achieved via subxiphoid or limited median sternotomy off-pump.
- Sheath introduced directly into RV free wall. Amplatzer muscular VSD device deployed under TEE guidance without fluoroscopy.
Intraoperative Stenting
- Stent placement in pulmonary arteries or veins during open-heart surgery.
- Allows deployment of adult-sized stents in small infants, avoiding complex patch angioplasty and limiting CPB duration.
Electrophysiology and Arrhythmia Management
Catheter Ablation
- Utilizes radiofrequency (resistive/conductive heating) or cryothermal (hemispherical "iceball") energy.
- Cryothermal ablation preferred near AV node to eliminate permanent heart block risk.
- Electroanatomic mapping systems (magnetic/impedance-based) localize abnormal scar tissue, generate propagation maps, and minimize/eliminate fluoroscopy.
- Indicated for recurrent supraventricular tachycardia (SVT), atrioventricular nodal reentrant tachycardia (AVNRT), Wolff-Parkinson-White (WPW) syndrome, intra-atrial reentrant tachycardia (IART), and monomorphic ventricular tachycardia (VT).
Cardiac Rhythm Devices
- Pacemakers: Transvenous or epicardial systems for sinus node dysfunction or AV block. Leadless pacemakers available but limited in small pediatrics due to 23 French introducer sheath size.
- Implantable Cardioverter-Defibrillator (ICD): Class I indication for secondary prevention in survivors of sudden cardiac arrest or sustained VT.
- Cardiac Resynchronization Therapy (CRT): Biventricular pacing indicated for systemic ventricular dysfunction (EF < 35%) with wide QRS complex (>150 ms) to improve NYHA functional class and LV/RV function. May require epicardial leads due to complex CHD anatomy.