Abstract
Background
The Wenckebach phenomenon of atrioventricular conduction is deemed a physiological response of the atrioventricular node to a high atrial rate. However, the reverse Wenckebach phenomenon is under-recognized.
Case Summary
We report an instance of reverse Wenckebach phenomenon developing into complete heart block in a 33-year-old man who experienced syncope after surgical repair of prolapsed bicuspid aortic valves. His condition was managed by temporary pacing. However, long-term follow-up demonstrated that the reverse Wenckebach phenomenon and severe heart block was reversible, avoiding the need for a permanent pacemaker.
Discussion
Reverse Wenckebach phenomenon can occur spontaneously and degenerate to complete heart block. Combined with our findings, early recognition and prompt intervention may save the patient at risk.
Take-Home Messages
The reverse Wenckebach phenomenon paradoxically indicates an atrioventricular block at the intra-Hisian or infra-Hisian level, heralding a more severe atrioventricular block in the near future. This phenomenon after valve surgery may be temporary.
Key words: aortic valve repair, atrioventricular block, reverse Wenckebach phenomenon
Graphical Abstract
History of Presentation
A 33-year-old man was admitted on May 21, 2021, for having a cardiac murmur for the past 2 months. He reported no dyspnea or syncope. Physical examination of the heart revealed a 2/6 diastolic murmur heard at the third intercostal space. The baseline electrocardiogram (ECG) showed sinus rhythm, with PR interval of 174 ms, QRS duration of 100 ms, and normal frontal QRS axis (Figure 1A). Results of his Holter monitoring showed that during exercised-induced sinus tachycardia, there was intermittent incomplete right bundle branch block (RBBB) and right deviation of frontal axis (Figure 1B). Echocardiography revealed prolapsed bicuspid aortic valves (BAVs) and severe aortic regurgitation (Videos 1 and 2), with a slightly enlarged left ventricle (anterior-posterior diastolic diameter: 58 mm) and a left ventricular ejection fraction of 65%. The patient was diagnosed as having congenital BAV, severe aortic regurgitation due to aortic valve prolapse, and an enlarged left ventricle and was assessed as being NYHA functional class I.
Take-Home Messages
-
•
The reverse Wenckebach phenomenon paradoxically indicates an intra-Hisian or infra-Hisian level atrioventricular block, heralding a more severe atrioventricular block in the near future.
-
•
This phenomenon after valve surgery could be temporary.
Figure 1.
Electrocardiograms During the Patient's Hospital Stay
(A) On admission. (B) Incomplete right bundle branch block seen during exercise-induced sinus tachycardia before surgery. (C) Immediately after surgery showing incomplete right bundle branch block.
Surgical repair of the BAV was performed under general anesthesia and hypothermic cardiopulmonary bypass on May 26. During the procedure, a Dacron patch was fashioned into an annuloplasty ring to stabilize the aortic annulus. The prolapsed aortic valve leaflet was plicated. Competence of the repaired valve was confirmed intraoperatively by saline injection test. Transesophageal echocardiography revealed mild to moderate aortic regurgitation; therefore, the heart was recooled and the ascending aorta was reclamped. The aortic suture line was reopened, and additional plication of the prolapsed aortic leaflet was performed, with extended reinforcement. Repeat saline testing showed satisfactory valve competence. Postoperative transesophageal echocardiography demonstrated trace aortic regurgitation. The total cardiopulmonary bypass and cross-clamp times were 192 and 135 minutes, respectively. The circulation in the heart was cooled by a 4 °C cardioplegia solution. The nadir rectal temperature was 31.3 °C and 32.7 °C for the 2 cardiopulmonary bypasses. The patient was successfully weaned from the cardiopulmonary bypass. Epicardial pacing wires were placed. Hemostasis was achieved, and the chest was closed.
Immediate postoperative ECG showed sinus rhythm with incomplete RBBB and normal frontal QRS axis (Figure 1C). Echocardiography showed normal aortic valve anatomy and trace regurgitation (Videos 3 and 4). The patient recovered well, and the epicardial pacing wires were extracted on postoperative day 3 given uneventful heart rhythm monitoring. At 14:24 on June 1 (postoperative day 6), the patient reported a sudden palpitation. ECG tracing corresponding to the patient's symptom revealed irregular rhythm and intermittent wide QRS complexes (Figure 2). A few minutes later, the ECG returned to normal and the patient reported no symptoms. However, he experienced syncope at 18:40. Telemonitoring showed high-degree atrioventricular block (AVB) with intermittent alternate conduction through the left or right bundle branch (Figures 3A and 3B), which evolved to total cardiac arrest with a maximal pause of 7.4 seconds (Figure 3C).
Figure 2.
Electrocardiogram From Postoperative Day 6 When the Patient Experienced Palpitation
Figure 3.
Consecutive Electrocardiograms on Telemonitoring
(A) First and (B) second episode of high-degree atrioventricular block. (C) Total cardiac arrest for 7.4 seconds.
Past Medical History
The patient was otherwise healthy and reported no history of other related diseases.
Differential Diagnosis
The clustering of QRS into groups raised the suspicion of Wenckebach phenomenon. Through careful examination of the patient's ECG (Figure 4), a regular sinus rhythm with a PP interval of 600 ms was found, which was marked by P1, P2, and P3, with the missed P-wave (P2) superimposed on the previous T-wave. The narrow QRS following this P-wave was definitely normal antegrade conduction through the atrioventricular node. However, the wide QRS complex with the morphology of complete left bundle branch block should have been differentiated between a conducted beat following the preceding P-wave, or merely a junctional escape during high-degree AVB. A fixed PR interval of 360 ms between the P1 waves and the subsequent wide QRS complex (ie, PR1) confirmed the conduction relationship between the P1 and QRS wave, arguing against the possibility of the wide QRS complex as an escape beat. Therefore, in every 3:2 Wenckebach cycle, the first PR interval (PR1 = 360 ms) after the pause due to the nonconducted P-wave was longer than the PR interval (PR2 = 200 ms) of the second beat after a relatively shorter RP interval. This positive RP/PR correlation was interpreted as a reverse Wenckebach phenomenon, in contrast to the Wenckebach phenomenon, which has a negative RP/PR correlation. Also, paradoxically, each long PR interval was followed by an intraventricular conduction block, while each short PR interval was followed by normal intraventricular conduction.
Figure 4.
Illustration of Reverse Wenckebach Phenomenon
A = atrium; AVN = atrioventricular node; BB = bundle branch; V = ventricle.
The ECG could be also interpreted as an apparent “supernormal conduction”.1 The poor anterograde conduction with longer PR interval and wider QRS could be interpreted as the baseline conduction status, while the normal PR and narrower QRS following the second P-wave could be a supernormal conduction. However, the baseline conduction before symptom onset and after the resolution of the symptom both showed a normal sinus rhythm and atrioventricular conduction, which did not support a true supernormal conduction in this case.
Another possibility was the 1:2 conduction of P1 to the ventricle due to the dual atrioventricular nodal pathway, in which the first QRS was wider, the second QRS was narrower, and the QRS duration was negatively correlated with the PR interval. However, this should coincide with a missed sinus P-wave, which would have to be explained by sinoatrial block. Lack of evidence of sinus dysfunction and dual atrioventricular nodal pathway physiology in this patient and the requirement of coincidence of sinoatrial block and AVB rendered this explanation less possible.
Management
A temporary pacemaker was implanted in emergency. After 7 days of close observation, there was no more recurrence of conduction block, and the temporary pacemaker was removed. After a thorough discussion with the patient, he refused the implantation of a permanent pacemaker and was discharged thereafter.
Outcome and Follow-Up
The patient experienced no syncope and had normal daily activity over the 4-year follow-up period. The 3-month, 6-month, and all yearly follow-ups by Holter monitoring at the electrophysiological outpatient department showed incomplete RBBB (Figure 5).
Figure 5.
Electrocardiogram at 4-Year Follow-Up Showing Incomplete Right Bundle Branch Block
Discussion
The Wenckebach phenomenon (ie, PR interval inversely proportional to the previous RP interval) is a normal antegrade conduction property of the atrioventricular node. However, the reverse Wenckebach phenomenon, in which the PR interval is proportional to the previous RP interval, is the result of a diseased His-Purkinje system leading to phase 4 depolarization of the intra- or infra-Hisian conduction system during bradycardia. When the heart rate slows down or a long RR interval is brought about by a prior heart block or premature beat, the phase 4 depolarization makes the membrane potential move toward zero. Then, the subsequent conduction can be disturbed because of total or partial inactivation of voltage-gated sodium channels. This will cause a complete block or intraventricular conduction delay.
In this patient, the reverse Wenckebach phenomenon occurred after surgical repair of BAV, which to our knowledge has not been reported. The incidence of complete heart block is relatively low in open heart aortic valve surgery compared with transcatheter aortic valve replacement (6.1% vs 17.4%).2 The pre-existence of intermittent incomplete RBBB might have increased the risk of AVB for surgery involving the aortic valve. This was further complicated by the redo process after the first unfavorable repair, which prolonged the procedural time, aggravated local tissue edema, and caused more trauma to the conduction system.
Yan3 delicately demonstrated the normal and inverse decremental conduction in the left bundle branch before and after the procedure by drafting coordinates of the RP interval and PR interval. The similarity of his findings with ours was that both cases presented baseline RBBB, which pointed to the fact that the left bundle branch was more prone to the lesion and this phenomenon. But the unique presentation of 3:2 Wenckebach phenomenon observed in our case has not to our knowledge been reported in iatrogenic circumstances before. Also, besides iatrogenic etiology, this phenomenon can occur spontaneously.4 The acute progression to more severe conduction block as demonstrated in these case reports indicates that the reverse Wenckebach phenomenon is not benign but portends imminent complete heart block. This would suggest the need for temporary pacing or for delaying the withdrawal of temporary pacing (including epicardial pacing wires) if it was already implanted during the procedure.
To be noticed, a long-term follow-up of >4 years without any recurrence of permanent or intermittent AVB underscores the fact that severe intra- or infra-Hisian block and AVB after cardiac surgery may be reversible. Therefore, it is advisable to observe the patient for a certain period to avoid unnecessary implantation of a permanent pacemaker. It is generally recommended that the implantation of a permanent pacemaker after surgery should be postponed for at least 5 to 7 days,5 and it should be determined on a case-by-case basis. A recent single-arm cohort study reported a 75.7% reduction of permanent pacemaker implantation by using a temporary-permanent pacemaker during a 1-month observation period.6
Conclusions
The reverse Wenckebach phenomenon indicates severe intra- or infra-Hisian block, and it may portend imminent high-degree AVB, which could be life-threatening. Prompt temporary pacing was warranted in our patient to avoid the disastrous result of cardiac arrest. But in the long run, the reverse Wenckebach phenomenon and severe heart block after open heart surgery may still be reversible, and it does not sufficiently indicate permanent pacemaker implantation.
Funding Support and Author Disclosures
This work was supported by the Yunnan Provincial Clinical Medicine Research Special Program-Research Project on the Application of Diagnostic and Therapeutic Technologies and Capacity Enhancement Centered on Innovative Cardiovascular Diagnosis and Treatment Devices (project number: 202405AJ310003). The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
Footnotes
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the Author Center.
Appendix
Visual Summary.
| Date | Events |
|---|---|
| Date of admission/day 1 | A 33-year-old man was admitted for having a cardiac murmur for 2 months. Baseline ECG was normal. The echocardiography revealed prolapsed bicuspid aortic valves and severe aortic regurgitation with slightly enlarged left ventricle (anterior-posterior diastolic diameter: 58 mm) and a normal left ventricular ejection fraction of 65%. |
| Day 6 | The patient underwent surgical repair of the bicuspid aortic valve under general anesthesia and hypothermic cardiopulmonary bypass. Postoperative transesophageal echocardiography demonstrated trace aortic regurgitation. Immediate postoperative ECG showed sinus rhythm with incomplete RBBB and normal frontal QRS axis |
| POD 6 | The patient reported a sudden palpitation. ECG tracing corresponding to the patient's symptoms revealed reverse Wenckebach phenomenon. He later experienced syncope, and telemonitoring showed high-degree AVB and total cardiac arrest, with a maximal pause of 7.4 seconds. A temporary pacemaker was implanted in emergency. |
| POD 14 | After 7 days of close observation, there was no more recurrence of conduction block, and the temporary pacemaker was removed. After a thorough discussion with the patient, he refused the implantation of a permanent pacemaker and was discharged. |
| 4-y follow-up | The patient experienced no syncope and had normal daily activity over the 4-year follow-up period. The 3-month, 6-month, and all yearly follow-ups after the index procedure showed incomplete RBBB according to ECG and Holter monitoring. |
Appendix
Bicuspid Aortic Valve Shown on Preprocedural Echocardiography (Short-Axis View at the Base)
Severe Aortic Regurgitation Shown on Preprocedural Doppler Echocardiography (Parasternal Long-Axis View)
Normal Aortic Valve Anatomy Shown on Postprocedural Echocardiography (Short-Axis View at the Base)
Trace Aortic Regurgitation Shown on Postprocedural Doppler Echocardiography (Parasternal Long-Axis View)
References
- 1.Moore E.N., Spear J.F., Fisch C. “Supernormal” conduction and excitability. J Cardiovasc Electrophysiol. 1993;4:320–337. doi: 10.1111/j.1540-8167.1993.tb01234.x. [DOI] [PubMed] [Google Scholar]
- 2.Popma J.J., Deeb G.M., Yakubov S.J., et al. Transcatheter aortic-valve replacement with a self-expanding valve in low-risk patients. N Engl J Med. 2019;380:1706–1715. doi: 10.1056/NEJMoa1816885. [DOI] [PubMed] [Google Scholar]
- 3.Yan G.X. Inverse decremental conduction heralds complete atrioventricular block following transcatheter aortic valve replacement. Heartrhythm Case Rep. 2021;7:820–824. doi: 10.1016/j.hrcr.2021.09.003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 4.Zahid M., Arora S. Reverse Wenckebach “pseudo-supernormal” conduction or paroxysmal atrioventricular block. J Cardiovasc Dis Res. 2012;3:225–227. doi: 10.4103/0975-3583.98898. [DOI] [PMC free article] [PubMed] [Google Scholar]
- 5.Kusumoto F.M., Schoenfeld M.H., Barrett C., et al. 2018 ACC/AHA/HRS guideline on the evaluation and management of patients with bradycardia and cardiac conduction delay: a report of the American College of Cardiology/American Heart Association task force on clinical practice guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019;74:e51–e156. doi: 10.1016/j.jacc.2018.10.044. [DOI] [PubMed] [Google Scholar]
- 6.Chang S., Jiang Z., Liu X., et al. Permanent pacemaker reduction using temporary-permanent pacemaker as a 1-month bridge after transcatheter aortic valve replacement: a prospective, multicentre, single-arm, observational study. EClinicalMedicine. 2024;72 doi: 10.1016/j.eclinm.2024.102603. [DOI] [PMC free article] [PubMed] [Google Scholar]
Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Supplementary Materials
Bicuspid Aortic Valve Shown on Preprocedural Echocardiography (Short-Axis View at the Base)
Severe Aortic Regurgitation Shown on Preprocedural Doppler Echocardiography (Parasternal Long-Axis View)
Normal Aortic Valve Anatomy Shown on Postprocedural Echocardiography (Short-Axis View at the Base)
Trace Aortic Regurgitation Shown on Postprocedural Doppler Echocardiography (Parasternal Long-Axis View)