Transient Sinus Arrest after Chest Wall Injury

Sir, Blunt cardiac injury (BCI) encompasses a spectrum of pathologies ranging from clinically silent, transient arrhythmias to deadly cardiac wall rupture. Due to the absence of clear diagnostic criteria and reliable tests, reporting BCI cases becomes challenging.[1,2] The use of troponin, in combination with ECG, is also suggested to identify patients at risk of complications resulting from myocardial contusion.[1,2] The patient was a 66-year-old man who was injured when he crashed his 50 cc motorcycle into a roadside ditch. The patient had a history of chronic hepatitis C and hypertension. He was transported to our hospital by ambulance. On arrival, he had hypertension and tachypnea with hypoxia. The patient had flail chest on the left side. Electrocardiogram (ECG) showed a complete right bundle branch block (CRBBB). Traumatic pan scan images revealed lung contusion and a flail segment with heart compression [Figure 1]. A blood analysis revealed increased troponin I. The clinical diagnosis was left flail chest, lung contusion, and heart contusion. He underwent endotracheal intubation, followed by mechanical ventilation and positive pressure ventilation to achieve internal stabilization. After admission to the intensive care unit, he underwent continuous infusion of dexmedetomidine. He showed sinus arrest, which spontaneously recovered [Figure 1]. Accordingly, dexmedetomidine was ceased on day 2, and sinus arrest was not observed. During intensive care, he developed ventilator-associated pneumonia, and atrial fibrillation and underwent tracheostomy. After the discontinuation of sedation, no evidence of sinus pauses was observed. The patient’s breathing pattern remained normal on day 14. A follow-up computed tomography scan on day 18 revealed improvement in the compression of the right ventricle due to rib fractures. His ECG findings returned to normal without CRBBB. Holter ECG on day 20 showed no sinus arrest. He was transferred to another hospital for rehabilitation on day 27.Figure 1: (a) Electrocardiogram (ECG), upper left and chest computed tomography (CT), lower left on arrival, and electrocardiography after admission (right). The ECG showed complete right bundle branch block (a). The CT showed the chest wall, with a flail segment compressing the right heart (arrow) (b). After admission to the intensive care unit, the patient showed sinus arrest (c), which spontaneously resolvedThe present case report showed transient sinus arrest, CRBBB, and AF after BCI. Arrhythmias are common after cardiac contusion, occurring in up to 70% of patients within 3 days of hospitalization for BCT. RBBB is considered the most common cardiac conduction disorder associated with BCI, potentially due to the anterior location of the right side of the heart, similar to the present case.[2] Arrhythmias that have been described include sinus tachycardia, uniform premature ventricular complexes (PVCs), multifocal PVC, AF, left BBB, atrioventricular (AV) block, ventricular fibrillation, ventricular tachycardia, and supraventricular tachycardia.[2,3] After sinus tachycardia, AF is the next most common arrhythmia.[2] To the best of our knowledge, this is the first case of sinus arrest (pause) after flail chest with BCI. Baxter et al. reported an animal model with myocardial contusion produced by a single blow with a weighted pendulum.[4] The impact resulted in a complete electrical arrest (sinus arrest), followed by sequential ventricular, atrial, and AV nodal recovery. Baxter’s experiment suggested that BCI could induce sinus arrest. The differential diagnosis included an adverse effect of dexmedetomidine. Cases with sinus arrest without escape beats are extremely rare but have been reported.[5] The present case suggests that the use of dexmedetomidine should be avoided in cases of BCI. Research quality and ethics statement This study was approved by the Institutional Review Board (Juntendo Shizuoka Hospital Ethics Committee IRB # 298). All authors followed applicable EQUATOR Network (http://www.equator-network.org/) guidelines, notably the CARE guideline, during the conduct of this report. Declaration of patient consent We certify about having obtained all appropriate patient consent forms. In the form, the patient has given his consent for his images and other clinical information to be reported in the journal. The patient understands that his name and initials will not be published and due efforts will be made to conceal his identity, but anonymity cannot be guaranteed. Financial support and sponsorship This work was supported in part by a grant-in-aid for special research in subsidies for ordinary expenses of private schools from the promotion and mutual aid corporation for private schools of Japan. Conflicts of interest There are no conflicts of interest.