|Year : 2014 | Volume
| Issue : 2 | Page : 49-50
Electrocution induced symptomatic bradycardia necessitating pacemaker implantation
Kuan Leong Yew
Department of Cardiology,Sarawak General Hospital Heart Center, Kota Samarahan, Sarawak, Malaysia
|Date of Web Publication||24-Jul-2014|
Kuan Leong Yew
Heart Center, Sarawak General Hospital, Kota Samarahan, Sarawak
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Electrical or electrocution injury is a common accidental occurrence and mostly workplace related. Fatal arrhythmias, skin injury and sudden death may ensue. However, it is rare for electrocution to result in permanent low rate sinus bradycardia, incompatible with an active lifestyle. The probable mechanisms for this pathological sinus bradycardia are sinus node dysfunction and autonomic dysfunction with vagal predominance. We describe a young patient who suffered a non fatal electrocution with resultant low rate sinus bradycardia and its successful treatment with a dual chamber rate responsive pacemaker.
Keywords: Autonomic resetting, electrical injury, electrocution, pacemaker, poor chronotropic response, sinus bradycardia, vagal tone predominance
|How to cite this article:|
Yew KL. Electrocution induced symptomatic bradycardia necessitating pacemaker implantation. Heart Views 2014;15:49-50
| Introduction|| |
Accidental electrical injury may cause tissue damage and even death. It can result from electrical or lightning injury. For workplace related electrocution, male workers are mostly at risk. Various organs can be affected resulting in skin burn, musculoskeletal injury, myoglobinuria and ventricular fibrillation. The electrical surge may also damage the heart conduction system resulting in various types of heart block. In this case, the survivor of electrocution developed persistent low rate sinus bradycardia, a phenomenon not yet described in the literature.
| Case report|| |
A 35-year-old electrician was doing electrical maintenance work in a shopping mall. He was holding a wire cable when the main electrical switch box suddenly exploded, throwing him a few feet away. Prior to that, he could feel electrical current streaming through his body. There was second degree burn on both hands and his head hair was completely singed with no loss of consciousness or palpitation. He was brought to the nearest district hospital with normal blood pressure but heart rate of about 35 beats per min (bpm). During the hospitalization, there was no other complication of the electrocution and the burn wound was treated with the appropriate dressing. The cardiac enzymes and renal profile were normal. However, he remained in sinus bradycardia.
Hence, he was transferred to our center after one week of the index event for further assessment and consideration of pacemaker device implantation. At our center, we subjected him to an exercise stress test (EST). The baseline heart rate was 35 bpm and it rose to 60 bpm during Stage 3 of the EST, achieving 7.10 METS and 32% of maximal age-predicted heart rate. He could only proceed till Stage 3, limited by physical endurance fatigue. When he tried to ambulate to go to the toilet, he experienced a few episodes of near fainting. After waiting for 3 weeks for his burn wound on the hand to heal, we proceeded to implant a dual chamber rate responsive pacemaker Sensia SEDR01 ® (Model SESR01, Medtronic, Inc., Minneapolis, MN, USA). He had been coming back to our pacemaker clinic for yearly interrogation and we found him to be totally pacing dependent.
| Discussion|| |
Electrical or electrocution injuries are synonymous with excessive, unintended electrical current exposure and subsequent complications. It can be broadly divided into workplace related or environmental related electrical injuries such as caused by lightning. Children and adult blue collar males are prone for accidental electrical injuries as a result of careless and inquisitive nature, and exposure to electrical hazards in the workplace, respectively. The electrocution happens when there is flow of electrons due to potential difference.
The factors influencing electrical injury are the type of current [direct current (DC) or alternating current (AC)], voltage, resistance and total exposure time. The electrical injury can be direct immediate effect on the body, thermal injury or consequent mechanical injury. Any organ or body tissue can be affected, either singly or involving multi-organ. DC exists in lightning while household and commercial premises are supplied by AC system. It was unfortunate that this electrician was electrocuted while doing some cable wiring work. As he was exposed to AC, this could have stimulated skeletal muscle tetany, persistently prolonging his grip on the culprit cable wire and further damaging electrical exposure, but he was fortuitously aided by simultaneous switch box explosion which generated enough shock wave to propel the patient away from the electrocution source and break his body from being continuously forming part of the harmful electrical circuit. The short contact time may have explained his limited second degree burn on his exposed hands only and other organs mostly unscathed.
Skin is the largest organ in the body. Not surprisingly, skin burn is a common electrocution complication ranging from 57-96% of a postmortem study of 220 fatal cases.  Skin burn may range from superficial first degree burn to full thickness third degree burn in association with the extent of the skin area involved.
For any bystander or first medical staff contact, the first important step is assessment of the airway, breathing and circulation before more detail examination. Prompt cardiopulmonary resuscitation (CPR) should be initiated if there is any hemodynamic instability and cardiac arrhythmias. The most immediate life threatening arrhythmias are asystole and ventricular fibrillation at the time of electrocution.  The patient ought to be hospitalized for further observation as some injuries may only manifest later such as rhabdomyolysis, acute kidney failure, head injury and subtle orthopedic fractures. He should be cared in an acute setting to monitor for recurrence of the malignant arrhythmias and evidence of myocardial injury with cardiac enzymes, electrocardiogram (ECG) and telemetry. Rise in cardiac enzymes usually denotes cardiac contusion. If there is any occurrence of ST elevation myocardial infarction (STEMI), the aetiology is most probably coronary vasospasm rather than acute thrombotic occlusion.
The electrical conduction system of the heart maybe damaged as well, resulting in other dysrhythmias such as first degree heart block, second degree heart block and bundle branch block. From the autopsy report, focal necrosis was found in the myocardium, as well as the sinus and atrioventricular node (AV),  thus explaining for the heart blocks phenomenon. This patient had sinus bradycardia with every P wave conducted through the AV node, resulting in ventricular response rate of 35 bpm most of the time. No other ventricular escape beat was noted. EST was an informative test for assessing his chronotrophic response and functional status. He had inadequate chronotrophic response in particular from the sinus node. No doubt the sinus node was damaged from the electrical injury. However, the constant steady heart rate at 35 bpm invariably suggested some form of autonomic system resetting with higher vagal predominance. Surely with this new low baseline heart rate, his daily lifestyle would be severely curtailed. He was still young and his work involved active field work.
In this instance, a pacemaker device would definitely benefit him. As he was recovering from his burn injury, the timing of pacemaker implantation was of paramount importance as unhealed or active skin infection may lead to pacemaker infection and its complications.  There was no need for temporary pacing. This afforded us the luxury of time to wait for the skin to heal. A dual chamber rate responsive pacemaker was chosen with the dysfunctional sinus node in mind, as well as for optimal AV synchrony. It was of no surprise that he was now totally pacing dependent with satisfying achievable activities, demonstrating the fact that the damage on the heart conducting system was permanent.
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