Introduction
Pulmonary valve replacement is a well-established intervention for right ventricular outflow tract dysfunction after repair of tetralogy of Fallot. Transcatheter pulmonary valve replacement has emerged as a widely adopted alternative to surgery, offering favourable haemodynamic outcomes in appropriately selected patients. The Harmony valve, a self-expanding device designed for implantation in native or patched right ventricular outflow tracts, has demonstrated encouraging clinical performance. Reference Goldstein, McElhinney and Gillespie1
Although conduction abnormalities following transcatheter pulmonary valve replacement have been reported, they remain uncommon and tend to be transient. Reference Ruf, Eicken and Hess2,Reference Zhou, Tian and Tu3
We report a case of delayed high-grade atrioventricular block several days after Harmony transcatheter pulmonary valve replacement in an adult patient with repaired tetralogy of Fallot, systemic sarcoidosis, and triple bundle branch block, and permanent pacing was ultimately required. This case underscores the importance of rhythm surveillance in transcatheter pulmonary valve replacement recipients with a preexisting conduction system vulnerability.
Case report
A 52-year-old man underwent complete tetralogy of Fallot repair at 4 years of age. At 43 years of age, he developed atrial flutter, which was successfully treated with radiofrequency catheter ablation the following year. During the same period, a skin biopsy confirmed sarcoidosis, and the patient remained under long-term follow-up for systemic involvement.
An 18F-fluorodeoxyglucose positron emission tomography, conducted at 54 years of age, revealed increased uptake in the hilar lymph nodes, skin, multiple pulmonary nodules, and neural tissue without abnormal myocardial accumulation (Figure 1(a)), suggesting the absence of active cardiac sarcoidosis. The patient continued intermittent low-dose corticosteroid therapy.
( a ) 18F-fluorodeoxyglucose positron emission tomography demonstrating increased uptake in the bilateral hilar lymph nodes, skin lesions, and multiple pulmonary and neural sites. No significant myocardial uptake is seen, consistent with the absence of active cardiac sarcoidosis. ( b ) Electrocardiograms showing preoperative triple bundle branch block (right bundle branch block, left anterior fascicular block, and first-degree atrioventricular block). ( c ) Three-dimensional reconstructed contrast-enhanced cardiac computed tomography demonstrating anterior (i) and lateral (ii) views for preprocedural assessment of right ventricular outflow tract morphology before harmony transcatheter pulmonary valve replacement. MPA = main pulmonary artery; RV = right ventricle.
Figure 1. Long description
The composite image consists of three distinct elements: a PET scan, electrocardiograms, and 3D reconstructed cardiac CT scans. The PET scan on the left shows increased uptake in the bilateral hilar lymph nodes, skin lesions, and multiple pulmonary and neural sites, with no significant myocardial uptake, indicating the absence of active cardiac sarcoidosis. The middle section displays electrocardiograms showing preoperative triple bundle branch block, including right bundle branch block, left anterior fascicular block, and first-degree atrioventricular block. The right section features 3D reconstructed contrast-enhanced cardiac CT scans, providing anterior and lateral views for preprocedural assessment of the right ventricular outflow tract morphology before harmony transcatheter pulmonary valve replacement. The main pulmonary artery and right ventricle are labeled in the CT scans.
Nonetheless, the right ventricular dilation and biventricular dysfunction gradually progressed. Preoperative electrocardiography demonstrated right bundle branch block, left anterior fascicular block, and first-degree atrioventricular block, consistent with a triple bundle branch block (Figure 1(b)). Cardiac magnetic resonance imaging revealed severe pulmonary regurgitation (regurgitation fraction, 54%), marked right ventricular enlargement (right ventricular end-diastolic volume index, 329 mL/m2; right ventricular end-systolic volume index, 237 mL/m2), and a 27% right ventricular ejection fraction. The left ventricle was mildly dilated (left ventricular end-diastolic volume index, 122 mL/m2), with a 34% ejection fraction.
Over the year preceding the intervention, the patient gradually experienced worsening exertional dyspnoea and easy fatigability, which increasingly limited daily activities. These symptoms were consistent with a right-sided volume overload and biventricular dysfunction, and pulmonary valve replacement was considered appropriate. Preprocedural contrast-enhanced computed tomography demonstrated a suitable native right ventricular outflow tract morphology for the Harmony device (Figure 1(c)), and Harmony transcatheter pulmonary valve replacement was selected based on anatomical compatibility.
A 25-mm self-expanding Harmony transcatheter pulmonary valve (Medtronic, Minneapolis, MN, USA) was successfully implanted under general anaesthesia via a transfemoral venous approach. A stiff guidewire was advanced into the right pulmonary artery. Based on preprocedural three-dimensional computed tomography, which showed a discrete narrowing point in the mid main pulmonary artery, the valve was deployed in an annular position, with the distal rows positioned at this site and the proximal rows extending into the right ventricular outflow tract (Supplementary Video 1). No conduction abnormalities or haemodynamic instability were observed during the procedure.
The early postoperative course was initially stable, with no atrioventricular conduction disturbance on postoperative day 1 (Figure 2(a)(i)). However, on postoperative day 3, the patient developed dizziness and marked bradycardia (heart rate 35 bpm), and electrocardiography revealed advanced atrioventricular block (Figure 2(a)(ii)). A temporary pacemaker was inserted, and electrophysiological testing confirmed an infra-Hisian block.
( a ) Two-lead electrocardiograms obtained on (i) postoperative day 1 showing no atrioventricular conduction disturbance and (ii) postoperative day 3 demonstrating advanced atrioventricular block. ( b ) Parasternal short-axis transthoracic echocardiographic images obtained (i) before transcatheter pulmonary valve replacement, (ii) on postoperative day 3, and (iii) on postoperative day 10. Post-procedural studies demonstrate an increase in left ventricular end-diastolic dimension consistent with augmented left-sided preload after relief of pulmonary regurgitation. TPVR = transcatheter pulmonary valve replacement; RV = right ventricle; LV = left ventricle; LVDd = left ventricular end-diastolic dimension.
Figure 2. Long description
The image contains two-lead electrocardiograms and echocardiographic images. The electrocardiograms show readings from postoperative day 1 with no atrioventricular conduction disturbance and from postoperative day 3 demonstrating advanced atrioventricular block. The echocardiographic images are obtained before transcatheter pulmonary valve replacement, on postoperative day 3, and on postoperative day 10. These images show an increase in left ventricular end-diastolic dimension, indicating augmented left-sided preload after relief of pulmonary regurgitation. The right ventricle and left ventricle are labeled in the echocardiographic images.
Owing to biventricular dysfunction and pacing dependency, a cardiac resynchronisation therapy defibrillator was implanted on postoperative day 6. The patient recovered well and was discharged on postoperative day 12. Follow-up transthoracic echocardiography on postoperative days 3 and 10 demonstrated progressive changes in the left ventricular loading conditions, consistent with an increased preload (Figure 2(b)). By Simpson’s method, left ventricular end-diastolic volume also increased from 136 mL before implantation to 160 mL on postoperative day 10.
Discussion
Conduction disturbances following transcatheter pulmonary valve replacement are uncommon but clinically meaningful. Transient complete atrioventricular block has been described with balloon-expandable devices, such as the Melody valve, during implantation, Reference Ruf, Eicken and Hess2 and a delayed transient episode of complete atrioventricular block has been reported during follow-up after implantation of the self-expanding Salus valve. Reference Zhou, Tian and Tu3 In the current case, no conduction disturbances occurred during or immediately after the procedure. Nevertheless, the specific mechanisms have not been fully addressed in previous studies.
To our knowledge, high-grade atrioventricular block requiring permanent pacing after Harmony valve implantation has not been well documented. In our patient, the valve was deployed in an annular position, with the proximal rows extending into the right ventricular outflow tract, away from the expected location of the atrioventricular conduction tissue. In addition, no conduction changes were seen during the procedure, and the onset of advanced atrioventricular block on postoperative day 3 made direct mechanical injury to the conduction system less likely.
Delayed complete atrioventricular block has been reported for years or decades after tetralogy of Fallot repair. Reference Bolens and Friedli4 Proposed mechanisms include progressive fibrosis, scarring along the surgical suture line, and ischaemic changes affecting the central conduction system. The combination of the right bundle branch block and left anterior fascicular block, as well as the infra-Hisian block induced during atrial pacing, has been suggested as a susceptibility marker for late atrioventricular block in patients with repaired tetralogy of Fallot. Reference Hejazi, Balubaid and Alata5 These abnormalities were present in our patient before transcatheter pulmonary valve replacement, suggesting preexisting His–Purkinje system fragility due to surgical remodelling and potential sarcoidosis-related involvement.
Haemodynamic changes after transcatheter pulmonary valve replacement may further destabilise this vulnerable substrate. Notably, chronic pulmonary regurgitation relief improves forward stroke volume and can acutely increase left ventricular preload and chamber size. Moreover, Pagourelias et al. showed that left ventricular volume commonly increased after transcatheter pulmonary valve replacement. Reference Pagourelias, Daraban and Mada6 The left posterior fascicle is particularly sensitive to mechanical stress, Reference Dominguez and Fozzard7 and acute ventricular stretching has been demonstrated to alter Purkinje fibre conduction and provoke arrhythmias. Reference Hurley, Kaur and Walton8,Reference Hurley, Walton and Vigmond9 In this context, the observed increase in stroke volume and mild left ventricular enlargement may have imposed additional strain on the posterior fascicle, triggering a high-grade atrioventricular block in the conduction system that was already compromised by prior surgical and inflammatory processes.
This case underscores the possibility of delayed conduction deterioration after transcatheter pulmonary valve replacement, despite a stable intraprocedural rhythm. Therefore, clinicians should be aware of this potential complication, particularly in patients with a repaired tetralogy of Fallot, underlying conduction abnormalities, or systemic inflammatory diseases.
In conclusion, delayed high-grade atrioventricular block may occur after transcatheter pulmonary valve replacement despite a stable intraprocedural conduction. Patients with repaired tetralogy of Fallot or with systemic inflammatory diseases who exhibit baseline conduction abnormalities may be particularly susceptible. Early and continuous rhythm monitoring, along with readiness to provide pacing support, are essential for the postoperative management of high-risk transcatheter pulmonary valve replacement recipients.
Supplementary material
The supplementary material for this article can be found at https://doi.org/10.1017/S1047951126113389.
Data availability statement
Data sharing is not applicable to this article, as no datasets were generated or analysed in the current study.
Acknowledgements
None.
Financial support
This research received no specific grants from any funding agency, commercial sector, or not-for-profit sector.
Competing interests
The authors declare none.
Ethical standard
The authors assert that all procedures contributing to this work comply with the ethical standards of the relevant national guidelines on human experimentation and were approved by the Institutional Review Board of Osaka City General Hospital. Informed consent was obtained in the form of opt-out on the Osaka City General Hospital website.
