Left Anterior Descending Coronary Artery Compression After Harmony Transcatheter Pulmonary Valve Implantation

Case presentation

Patients with tetralogy of Fallot frequently develop pulmonary regurgitation following transannular patch repair. Percutaneous pulmonary valve implantation has been increasingly adopted for these patients.¹ The Harmony transcatheter pulmonary valve (Medtronic) is a porcine pericardial valve mounted on a self-expanding nitinol frame covered with polyester fabric. Its asymmetric hourglass design, characterized by a narrow central waist, has been reported to confer a low risk of coronary compression.^2,3 Acute coronary compression associated with this device is only rarely reported in the literature.^4,5

A 31-year-old woman with a history of tetralogy of Fallot repair in 1997 was referred for symptomatic, severe pulmonary regurgitation. Magnetic resonance imaging revealed a dilated right ventricle with an end-diastolic volume more than twice that of the left ventricle, alongside a borderline ejection fraction of 43%. The heart team consensus recommended percutaneous pulmonary valve implantation, as a surgical valve would be more complex given the anomalous left coronary artery across the right ventricular outflow tract (RVOT). Preprocedural computed tomography identified an anomalous left anterior descending artery (LAD) originating from the right coronary cusp and wrapping around the RVOT, creating multiple potential points of contact (Figure 1A-C). Initial preprocedural imaging revealed the left anterior descending artery traversing the anterior aspect at the annular level. Therefore, supra-annular Harmony valve implantation was expected to carry a low risk of coronary compression. In our institution, another viable platform is the VenusP-valve (Venus Medtech). However, given its stronger stent frame and increased expansion force at the body and flared ends, this option was considered to carry a higher risk of coronary compression. Therefore, the Harmony valve was selected (Figure 1D).

Figure 1.

Left anterior descending artery compression after percutaneous pulmonary valve implantation. (A) Preprocedural computed tomography showing the close relationship between the anomalous LAD and the MPA. (B, C) Three-dimensional reconstruction demonstrating the course of the coronary artery. (D) Predicted supra-annular landing zone on preprocedural fit analysis. (E) Baseline coronary angiogram showing the LAD crossing the anterior surface of the MPA (red arrow). (F) Balloon interrogation showed no change in the calibre of the left anterior descending artery (blue arrow). (G) Postimplantation coronary angiogram showing dynamic impingement of the LAD by the edge of the proximal valve flare (green arrow). (H) Coronary angiogram at 3 months postprocedure showing similar coronary calibre (yellow arrow). (I) Postoperative computed tomography showing the relationship between the valve stent and the LAD (purple arrow). Ao: aorta; LAD, left anterior descending artery; MPA, main pulmonary artery; RPA, right pulmonary artery.

The procedure was performed under general anesthesia. Baseline coronary angiography confirmed the computed tomography findings (Figure 1E). Although balloon interrogation is not routinely required per the manufacturer's instructions, it demonstrated no coronary compression at maximal inflation up to 40 mm (Figure 1F). The Harmony valve was deployed in a supra-annular position corresponding to the predefined optimal landing zone (Figure 1D). While annular implantation may reduce the risk of coronary compression by virtue of its narrow waist, this approach was considered impractical owing to the oversized proximal inflow of the RVOT, which would carry a substantial risk of valve embolization. The coronary diagnostic catheter was retained as a landmark. Angiography confirmed satisfactory valve position with no residual regurgitation. However, coronary angiography revealed non–flow-limiting impingement of the LAD during diastole caused by the edge of the proximal valve flare (Figure 1G). Given the anticipated difficulty in interpreting functional studies such as coronary flow reserve in the context of dynamic compression, these assessments were not performed. The patient remained hemodynamically stable, with no ischemic changes on electrocardiogram. Following discussion with the cardiothoracic surgeons, a decision was made to monitor conservatively, given the absence of flow disturbance and sustained hemodynamic stability.

The patient was monitored as an inpatient for 72 hours postprocedure, during which no new electrocardiographic changes or chest pain occurred. Given the potential for reduced main pulmonary artery dimensions or further prosthetic erosion into the coronary artery after relief of pulmonary regurgitation, follow-up coronary angiography and computed tomography were performed at 3 months. These investigations demonstrated a stable anatomical relationship between the prosthesis and the LAD, with no evidence of progressive compression (Figure 1H, I). Magnetic resonance perfusion imaging showed no stress-induced ischemia.

Discussion

Risk factors for coronary compression following percutaneous pulmonary valve implantation include close proximity between the coronary artery and the RVOT, the presence of a calcified conduit, and coronary anomalies such as an anomalous course. Contrary to the common perception that coronary compression risk is lower with the Harmony valve platform than with other stiffer self-expanding valves and balloon-expandable valves, compression may still occur due to the valve frame flares. The challenge illustrated by this case is achieving accurate positioning of the proximal flare to avoid coronary interaction, as the proximal flare in all self-expanding platforms is the last component to be released, making it almost impossible to know its exact landing position beforehand. Careful adjustment of the valve implantation position, guided by intraprocedural coronary angiography, may help prevent coronary artery impingement by the valve flares.

CRediT authorship contribution statement

Ka-Chun Un: Writing – review & editing, Writing – original draft, Methodology, Investigation, Data curation, Conceptualization. Chun-Ka Wong: Writing – review & editing, Validation, Methodology. Tomohito Kogure: Writing – review & editing, Supervision. Hay-Son Chen: Writing – review & editing, Supervision.

Declaration of competing interest

Dr. Kogure serves as a proctor for Medtronic, Japan.

Supplementary material

Video 1

Supra-annular positioning of the Harmony valve on pulmonary angiogram.

Video 2

Post-procedural selective coronary angiogram showed impingement of the left anterior descending artery by the proximal valve flare.