A Retrospective analysis of four cases of pacemaker exit block

Introduction: Exit block has been defined as a delay or failure of a pacemaker impulse to discharge the surrounding myocardium, including atrial and ventricular pacemaker exit blocks. The present report analyzed the etiology and electrocardiogram characteristics of pacemaker exit blocks, providing ideas for its diagnosis and treatment. Patient concerns: The patients in cases 1 and 2 sought medical advice for symptoms such as palpitations, chest tightness and shortness of breath. Both the patients had a dual-chamber pacemaker implant due to sick sinus syndrome Patients in cases 3 and 4 sought medical advice for symptoms such as chest tightness, chest pain, and dizziness. Both patients had a single-chamber ventricular pacemaker implant due to third-degree atrioventricular block. Diagnosis: Considering the symptoms and prolonged latency of atrial pacing, Cases 1 and 2 were diagnosed as first-degree atrial pacemaker exit blocks. Case 3 presented prolonged ventricular pacing latency, diagnosed as first-degree ventricular pacemaker exit block. Case 4 presented prolonged ventricular pacing latency and partial loss of capture diagnosed as second-degree ventricular pacemaker exit block. Interventions: In case 1, the patient required no treatment. In case 2, the AV interval was adjusted to ensure sequential pacing of the atrioventricular. In case 3, the serum potassium level was lowered. In case 4, the patient refused further treatment. Outcomes: In case 1, the patient had no discomfort, and the follow-up electrocardiogram was unchanged. The symptoms improved after treatment in case 2. After 1 year, the patient had no discomfort, and the follow-up electrocardiogram was similar to that before. In case 3, the exit block disappeared after lowering the serum potassium level. The pacemaker worked normally after 1 year of follow-up. In case 4, the exit block disappeared half an hour after the chest pain was relieved. The patient was lost to follow-up. Conclusion: A first-degree atrial pacemaker exit block may be misdiagnosed as atrial pacing dysfunction. This can be identified using the programming control of a pacemaker. For exit block of ventricular pacing, eliminating the cause of the disease is usually the most effective measure, and if necessary, a temporary pacemaker should be implanted.