Residency · Residency · Cardiothoracic Surgery

Transcatheter Aortic Valve Replacement: What the Surgeon Must Know

Introduction

Transcatheter aortic valve replacement (TAVR) has transformed the treatment of aortic stenosis, expanding from inoperable and high-risk patients to intermediate- and low-risk populations. The cardiothoracic surgeon plays a central role in the heart team, contributing to patient selection, procedural planning, access site management, complication rescue, and long-term follow-up. Understanding the indications, devices, techniques, and complications of TAVR is essential for the contemporary cardiac surgeon.

Indications

Current Guideline Recommendations

TAVR is indicated for severe symptomatic aortic stenosis, defined as an aortic valve area below 1.0 cm2, mean gradient above 40 mmHg, or peak velocity above 4.0 m/s. TAVR is now approved across the entire risk spectrum (low, intermediate, high, and prohibitive surgical risk). Age and life expectancy guide the choice between TAVR and SAVR: TAVR is preferred in patients over 80 years or with limited life expectancy (less than 10 years), while SAVR remains preferred for patients under 65 due to concerns about long-term valve durability and coronary access for future reintervention. Bicuspid aortic valve is increasingly treated with TAVR, though outcomes data are still maturing compared to tricuspid aortic valve disease.

Heart Team Decision-Making

Multidisciplinary assessment includes a cardiac surgeon, interventional cardiologist, imaging specialist, and anesthesiologist. Factors favoring SAVR include young age, bicuspid valve, need for concomitant procedures (CABG, mitral surgery), and complex anatomy unfavorable for TAVR. Factors favoring TAVR include advanced age, frailty, prior sternotomy, severe comorbidities, and porcelain aorta.

Preprocedural Planning

CT Angiography (Cardiac CT)

Cardiac CT is the cornerstone of preprocedural planning. Annular sizing involves measurement of annular perimeter, area, and diameters to select the appropriate valve size; undersizing risks paravalvular leak while oversizing risks annular rupture or conduction disturbance. Aortic root assessment evaluates sinus of Valsalva height and width, coronary ostial height (risk of coronary obstruction if less than 10-12 mm), and sinotubular junction dimensions. Iliofemoral assessment determines minimum vessel diameter, tortuosity, and calcification to establish transfemoral access feasibility (minimum 5.0-6.5 mm depending on device). Calcium distribution analysis identifies heavy leaflet or LVOT calcification, which predicts higher risk of paravalvular leak, conduction disturbance, and annular rupture.

Echocardiography

Echocardiography confirms the severity of aortic stenosis and assesses other valvular pathology. Left ventricular function is evaluated, and low-flow low-gradient AS requires dobutamine stress echocardiography. Concomitant mitral regurgitation is evaluated, as it may improve or worsen after TAVR.

Current TAVR Devices

Balloon-Expandable Valves

The Edwards SAPIEN 3 and SAPIEN 3 Ultra feature bovine pericardial leaflets mounted on a cobalt-chromium frame, deployed by balloon inflation. These valves offer precise positioning with minimal post-deployment migration, are available in sizes 20-29 mm, and include an outer sealing skirt that reduces paravalvular leak. Deployment requires rapid ventricular pacing (180-220 bpm) to minimize cardiac output and valve migration.

Self-Expanding Valves

The Medtronic Evolut R and Evolut PRO+ use porcine pericardial leaflets in a nitinol self-expanding frame, deployed by unsheathing. The supra-annular leaflet position provides a larger effective orifice area. These valves are recapturable and repositionable during deployment but carry a higher rate of new permanent pacemaker implantation (15-20%) compared to balloon-expandable valves (5-10%). Available sizes range from 23-34 mm.

Other Devices

The Boston Scientific ACURATE neo2 is a self-expanding, supra-annular design. The JenaValve uses clip-based anchoring and is available for transapical or transfemoral delivery; it is the only device approved for pure aortic regurgitation in some markets.

Access Routes

Transfemoral (Preferred)

Transfemoral access is the most common approach, used in over 95% of cases at experienced centers. Percutaneous access with a pre-close technique (2 ProGlide suture-mediated closure devices) or surgical cutdown requires adequate iliofemoral vessel diameter and absence of severe calcification or tortuosity.

Alternative Access (When Transfemoral Is Not Feasible)

Transaxillary/subclavian access requires surgical cutdown to the axillary or subclavian artery, with the surgeon's role being primary. Transcarotid access involves direct carotid artery cutdown and requires carotid duplex screening. Transapical access uses a left mini-thoracotomy with direct LV apex puncture but is declining in use due to higher mortality. Direct aortic (transaortic) access uses an upper mini-sternotomy with puncture of the ascending aorta. Transcaval access involves puncture through the IVC into the aorta with subsequent closure and is highly specialized.

Procedural Steps (Transfemoral)

The procedure begins with percutaneous femoral access and pre-closure with ProGlide devices. A pigtail catheter is placed in the aortic root for aortography. The stenotic aortic valve is crossed with a guidewire, followed by balloon aortic valvuloplasty (for balloon-expandable valves; optional for self-expanding). The delivery system is advanced and the valve positioned under fluoroscopic and TEE guidance. Deployment occurs with rapid ventricular pacing (balloon-expandable) or controlled unsheathing (self-expanding). Assessment includes aortography for paravalvular leak, hemodynamic measurements, and TEE evaluation. The delivery system is then removed and hemostasis achieved at the access site.

Complications and the Surgeon's Role

Vascular Complications

Iliofemoral dissection, perforation, or rupture occur in 5-10% of cases. The surgeon must be prepared for emergent surgical repair of femoral, iliac, or aortic injury. Covered stent placement addresses contained perforations, while open repair is required for hemodynamically significant injuries.

Annular Rupture

Annular rupture is a catastrophic complication (less than 1%) with high mortality, caused by oversizing or heavy calcification. It manifests as acute hemopericardium and hemodynamic collapse, requiring emergent pericardiocentesis, sternotomy, and open surgical repair or conversion to SAVR.

Coronary Obstruction

Coronary obstruction is rare (less than 1%) but life-threatening, caused by displacement of a calcified native leaflet over a coronary ostium. It is more common with low coronary heights, shallow sinuses, and large leaflet calcification. Treatment involves emergent PCI with stenting, and may require emergent CABG or ECMO support.

Paravalvular Leak

Mild paravalvular leak is common and well-tolerated, but moderate or greater leak is associated with increased mortality. Management includes post-dilation, valve-in-valve implantation, or surgical AVR for severe cases.

Conduction Disturbance

New left bundle branch block occurs in 10-30% of cases, and new permanent pacemaker implantation is needed in 5-20%, depending on valve type. Rates are higher with self-expanding valves and pre-existing conduction disease. Implantation depth is a modifiable risk factor, as deeper implantation increases conduction risk.

Stroke

Periprocedural stroke occurs in 1-3% of cases, and cerebral embolic protection devices are under investigation.

Long-Term Considerations

Current data suggest excellent hemodynamic performance at 5-8 years, but true long-term durability beyond 10 years remains uncertain, particularly in younger patients. Valve-in-valve TAVR is feasible for structural valve deterioration of prior TAVR or surgical bioprostheses, though coronary access can be challenging. Infective endocarditis occurs at 1-2% per year and often requires surgical intervention. Antithrombotic therapy consists of dual antiplatelet therapy for 3-6 months followed by aspirin alone, with anticoagulation added for concurrent atrial fibrillation.

Key Clinical Pearls

The cardiothoracic surgeon is an essential member of the TAVR heart team, contributing to patient selection, alternative access procedures, and complication management. Cardiac CT is the cornerstone of preprocedural planning, and accurate annular sizing prevents paravalvular leak and annular rupture. The surgeon must be prepared for emergent sternotomy and open surgical rescue of TAVR complications, including annular rupture, coronary obstruction, and device embolization. SAVR remains the preferred approach for patients under 65 due to proven long-term durability of surgical bioprosthetic and mechanical valves. As TAVR expands to lower-risk and younger patients, long-term valve durability and lifetime management strategy become the critical decision points.

References

1. Mack MJ, Leon MB, Thourani VH, et al. Transcatheter aortic-valve replacement with a balloon-expandable valve in low-risk patients. N Engl J Med. 2019;380(18):1695-1705.
2. Popma JJ, Deeb GM, Yakubov SJ, et al. Transcatheter aortic-valve replacement with a self-expanding valve in low-risk patients. N Engl J Med. 2019;380(18):1706-1715.
3. Otto CM, Nishimura RA, Bonow RO, et al. 2020 ACC/AHA guideline for the management of patients with valvular heart disease. Circulation. 2021;143(5):e72-e227.
4. Blanke P, Weir-McCall JR, Achenbach S, et al. Computed tomography imaging in the context of transcatheter aortic valve implantation. J Am Coll Cardiol. 2019;74(5):696-714.

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