Selective his bundle pacing eliminates crochetage sign: A case report

Abstract

BACKGROUND

Crochetage sign is a specific electrocardiographic manifestation of ostium secundum atrial septal defects (ASDs), which is associated with the severity of the left-to-right shunt. Herein, we reported a case of selective his bundle pacing (S-HBP) that eliminated crochetage sign in a patient with ostium secundum ASD.

CASE SUMMARY

A 77-year-old man was admitted with a 2-year history of chest tightness and shortness of breath. Transthoracic echocardiography revealed an ostium secundum ASD. Twelve-lead electrocardiogram revealed atrial fibrillation with a prolonged relative risk interval, incomplete right bundle branch block, and crochetage sign. The patient was diagnosed with an ostium secundum ASD, atrial fibrillation with a second-degree atrioventricular block, and heart failure. The patient was treated with selective his bundle pacemaker implantation. After the procedure, crochetage sign disappeared during his bundle pacing on the electrocardiogram.

CONCLUSION

S-HBP eliminated crochetage sign on electrocardiogram. Crochetage sign may be a manifestation of a conduction system disorder.

Key Words: Crochetage sign, Atrial septal defect, Pacemaker, Selective his bundle pacing, Case report

Core Tip: Crochetage sign is a characteristic electrocardiographic manifestation seen in patients with ostium secundum atrial septal defects. We reported the case of a patient with secundum atrial septal defect, atrial fibrillation, and second-degree atrioventricular block who received selective his bundle pacing (S-HBP) treatment. Subsequently, crochetage sign was eliminated by S-HBP. Crochetage sign may indicate a conduction system disease.

INTRODUCTION

With an incidence of 6%-10% after birth, atrial septal defect (ASD) is one of the most prevalent congenital heart diseases, with secundum ASD being the most common[1]. Because ASD's clinical presentation may be inconspicuous, optimal diagnostic methods remain challenging[2]. Several electrocardiogram (ECG) findings are thought to be sensitive for the diagnosis of ASD; hence, the ECG can be used as a helpful ASD screening tool. However, echocardiography remains the primary diagnostic tool for ASD[3].

One ECG finding associated with ASD is crochetage sign, which is a specific sign of ASD in the ostium secundum. Crochetage sign, similar to a crochet needle, is characterized by fragmented QRS complexes with a notch in the ascending portion or at the peak of the R-wave, which are typically observed in limb leads II, III, and aVF[4]. For secundum ASD, the sensitivity and specificity of this sign are higher when more inferior leads are involved. When crochetage pattern is seen in all three inferior leads, the specificity of this sign ranges from 92% to 100%[3]. The right bundle branch block (RBBB) on electrocardiography can further improve the specificity and sensitivity of crochetage sign[5]. Therefore, the appearance of crochetage sign on ECG is an important indicator of ASD, aiding in its early diagnosis. Previous studies showed that 35.1% of patients with ASD who underwent surgical closure experienced a disappearance of crochetage sign on their ECGs[6]. However, the disappearance of crochetage sign after cardiac pacing has not yet been reported. Herein, we report the case of a man with secundum ASD, atrial fibrillation, and a second-degree atrioventricular (AV) block. After receiving selective his bundle pacing (S-HBP) therapy, the crochetage sign on his ECG disappeared.

CASE PRESENTATION

Chief complaints

A 77-year-old man presented to our hospital complaining of chest tightness and shortness of breath for 2 years.

History of present illness

The patient complained of chest tightness and shortness of breath for 2 years. Symptoms appeared with activity, gradually resolved with rest, and worsened over the past 2 days, prompting the patient to seek treatment at our hospital.

History of past illness

The patient had no history of hypertension, type 2 diabetes mellitus, or coronary heart disease.

Personal and family history

The patient denied smoking, any significant drinking history, or any family disease history.

Physical examination

Vital signs were as follows: Body temperature, 36.7 ºC; Blood pressure, 122/76 mmHg; Heart rate, 61 beats per min; and Respiratory rate, 18 breaths per min. Both lungs produced coarse respiratory sounds and wet rales. The heart rate was irregular, cardiac sounds were decreased, and no murmur was detected. No cyanosis or lower limb edema was observed.

Laboratory examinations

The brain natriuretic peptide level was 622 pg/mL (reference range: 0-80 pg/mL), and the serum potassium level was 3.04 mmol/L (reference range: 3.2-5.3 mmol/L). Routine blood testing revealed normal liver, kidney, thyroid, and blood coagulation functions. Electrocardiography suggested atrial fibrillation with a prolonged relative risk interval; a notch near the apex of the R-wave in leads II, III, and aVF; and incomplete RBBB (Figure 1).

Figure 1 Initial electrocardiogram. A: Atrial fibrillation with a long relative risk interval; B: Atrial fibrillation with crochetage pattern in leads II, III, and aVF and incomplete right bundle branch block (arrows pointing toward crochetage sign are most common).

Imaging examinations

Transthoracic echocardiography (TTE) revealed a secundum ASD (Figure 2), severe tricuspid regurgitation, and mild mitral regurgitation. The left atrial diameter was 54 mm, left ventricular diameter was 33 mm, right atrial diameter was 66 mm, right ventricular (RV) diameter was 56 mm, and left ventricular ejection fraction was 75%.

Figure 2 Echocardiographic image. Echocardiography shows a secundum atrial septal defect that measured 2.32 cm.

FINAL DIAGNOSIS

The final diagnosis was a secundum ASD, atrial fibrillation with second-degree AV block (AVB), and heart failure.

TREATMENT

Considering the adverse effects of chronic RV pacing, we decided to perform HBP. A 3830 SelectSecure lead (Medtronic Inc., Minneapolis, MN, United States) was implanted in the his-bundle region (Figure 3). Pacing parameters were acceptable, with a capture threshold of 0.8 V/0.4 ms, sensitivity of 7 mV, and bipolar impedance at 570 Ω. A 5076-58 cm lead was implanted in the RV apex as a backup. Finally, a dual-chamber pacemaker (Medtronic Sensia SEDRL1; Medtronic Inc., Minneapolis, MN, United States) was implanted subcutaneously, with a 3830 lead connected to the atrial port and a 5076–58 cm lead connected to the ventricular port.

Figure 3 Fluoroscopic image. The fluoroscopic image shows that the 3830 lead was located in the His-bundle region. A: Right-anterior-oblique 30° view; B: Left-anterior-oblique 40° view.

OUTCOME AND FOLLOW-UP

After the procedure, the crochetage sign disappeared during HBP on electrocardiography (Figure 4). The patient received regular follow-up at the outpatient clinic. Pacemaker programming indicated normal functioning of both sensing and pacing.

Figure 4 Postoperative electrocardiogram. Electrocardiogram showing the disappearance of crochetage sign after his-bundle pacing.

DISCUSSION

ASDs are the most common heart defects in adults[7]. ASDs can cause heart failure, arrhythmic problems, and paradoxical embolism-related morbidity or death[2]. Many individuals with ASDs develop first-degree AVB, which is mostly caused by a prolonged intra-atrial conduction time[8]. Over time, a left-to-right shunt may cause cellular damage, decreased reservoir function, myocardial cell hypertrophy, and RV dilatation. Stretching myocardial fibers might alter their conductive properties, which could ultimately result in bradyarrhythmia or atrial tachyarrhythmia[9]. Some ASDs are hereditary and linked to cardiac conduction abnormalities such as bundle branch block or AVB[10]. ASD in patients with AVB may be related to a genetic mutation in myocardial transcription factors, such as NKX2.5, GATA4, and TBX5j, which are crucial for the development of the AV conduction system[8,10]. These include Holt–Oram syndrome, characterized by ASDs and conduction abnormalities such as sinus node dysfunction, AVB, atrial fibrillation, and RBBB[10].

Patients diagnosed with ostium-primum ASDs more commonly have higher-grade AV nodal conduction anomalies. AV nodal conduction disorders are uncommon in other forms of ASD[8]. The incidence of heart block in patients with ASD is unclear, and ASD with high-grade AV block is relatively uncommon[11]. Our patient had a second-degree AVB and atrial fibrillation, which are rare. His bundle pacing was then performed. The postoperative ECG revealed an isoelectric interval in all 12 leads, with the pacing spike to QRS onset equaling the native HV interval (35–55 ms). The QRS morphology was identical to that of the intrinsic rhythm, confirming S-HBP.

Crochetage sign refers to the presence of a notch in the initial 80 ms of the QRS complex in leads II, III and aVF, which resembles the shape of a crochet needle[12]. This sign is most frequently observed in individuals with ASD and can also be observed in other disorders such as patent foramen ovale (PFO), pulmonary embolism, and RV hypertrophy[11]. Recent research has revealed that, crochetage sign combined with RBBB and TTE had good performance for PFO prediction, with an accuracy, sensitivity, and specificity of 0.712, 0.801, and 0.439, respectively[13]. In the initial published research on crochetage, 73% of patients with ASD showed this pattern[14]. Crochetage sign is considered a characteristic presentation of secundum ASDs. When the pattern is seen in all three inferior leads, the specificity of this sign ranges from 92% to 100%[3]. The presence of a RBBB on the ECG considerably increases the specificity and sensitivity of crochetage sign for the diagnosis of ASD[3]. It has also been associated with the severity of the left-to-right shunt, and patients with ASD sizes of ≥ 5 mm showed a higher incidence of crochetage sign[6]. Because of its high sensitivity and specificity in diagnosing ASD, crochetage sign is a useful diagnostic tool[12]. Moreover, a retrospective clinical study demonstrated that the presence of crochetage sign was an independent predictor for late atrial arrhythmia among patients with secundum ASD who received transcatheter closure[15].

The underlying electrophysiological mechanism of crochetage sign is not fully understood, but many researchers believe that it is related to delayed RV depolarization due to RV volume overload[15]. Crochetage sign disappears in approximately 50% of patients after successful correction of ASD using percutaneous or surgical procedures[3,6]. Interestingly, in our case, crochetage sign disappeared on the ECG after S-HBP; however, the patient had not undergone atrial septal closure. We concluded that crochetage sign may be a manifestation of conduction system impairment. Based on the theory of longitudinal dissociation in the his bundle, conduction impairment may originate within the proximal his bundle because the pacing exceeded the injury level, and conduction through the His-Purkinje system was recovered, thus eliminating crochetage sign[16].

CONCLUSION

The exact mechanism underlying the development of crochetage sign has not yet been elucidated. Some patients with ASD closure experience crochetage signs that disappear from their ECG. Here, we report the case of a patient with ASD whose crochetage sign disappeared after selective his bundle pacing. Subsequently, we deduced that crochetage sign could be a manifestation of a cardiac conduction system injury. Future research is needed to explore the mechanism behind crochetage sign.