[in Japanese]

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[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

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In this case, we experienced Spike on T resulting from cardiac ventricle functional under-sensing, which occurred when the cardiac atrial pacing overlapped its own R wave subsequent to premature ventricular contraction (PVC). While extending the post-ventricular atrial refractory period (PVARP) can prevent pacemaker-mediated tachycardia by retrograde ventriculoatrial conduction, it also restricts maximal tracking rate. For this reason, there is an optional PVC function that allows PVARP to be extended once only after PVC sensing. The algorithm for the automatic extension of PVARP after PVC does not vary significantly among equipment manufacturers. However, there is a significant difference among manufacturers regarding the pacemaker response after sensing the P wave within the extended PVARP, and this difference can be one of the causes of the ventricular Spike on T wave, which we experienced in this case. In order to avoid the Spike on T that occurs when cardiac atrium pacing overlaps its own R wave subsequent to PVC, it is thought to be necessary to fully understand the differences of the response subsequent to PVC among manufacturers, and to program the device according to its characteristics.

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A 53-year-old man experienced five episodes of syncope while seated and two of urinary incontinence while asleep over a period of three years. He had no family history of cardiac disease, arrhythmias, or sudden death. He was in good health before the episodes, although ventricular premature contraction had been identified during an annual health check-up. He visited our hospital after the second syncopal attack. A Bruce protocol exercise stress test induced ventricular premature complexes, of which surface electrocardiography suggested a monofocal origin at the right ventricular outflow tract. Echocardiography confirmed the absence of organic abnormalities. Six months later, he participated in a head-up tilt test at a different facility, and vasodepressor-type neurally-mediated syncope was diagnosed. Over the following year, he experienced two episodes of syncope and one episode of incontinence before suddenly losing consciousness while watching TV at home. When paramedics arrived, they detected ventricular fibrillation that was converted to sinus rhythm with a single direct counter shock. Electrocardiogram monitoring in the ambulance during transit to our facility revealed ventricular premature complexes followed by torsades de pointes. A subsequent surface electrocardiogram in the emergency room showed neither Brugada type nor early repolarization. Nine months after ICD implantation, an appropriate shock worked while the patient was asleep during the early morning. This is a notable example of idiopathic ventricular fibrillation complicated with neurally mediated syncope and exercise-induced ventricular arrhythmia that originated from the right ventricular outflow tract.

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A 68-year-old male who underwent twice catheter ablation for atrial fibrillation about in another hospital, was admitted to our hospital for heart failure due to both of severe mitral regurgitation and atrial fibrillation on February 2010. At three months later, he received the mitral valve replacement and Maze procedure using cryoablation catheter. Although regular sinus rhythm was restored after the cardiac surgery, he suffered from repeated atrial tachycardia with heart rate of 210 bpm at 2 months after discontinuation of amiodarone. Therefore he decided to undergo catheter ablation to cure this atrial tachycardia. At baseline, delayed pulmonary vein potentials were recorded at all of the pulmonary veins. After extensive encircling pulmonary vein isolation, burst pacing from coronary sinus catheter provoked the clinical atrial tachycardia. Atrial tachycardia cycle was 320msec. Activation mapping with CARTO system revealed the clockwise macroreentrant peri-mitral atrial tachycardia and mitral isthmus linear ablation with endocardial approach was failed. Epicardial approach by positioning the ablation catheter into coronary sinus and radiofrequency application terminated the atrial tachycardia and created the complete linear lesions. The successful site of ablation is far from the endocardial common mitral isthmus line, and radiofrequency application from coronary sinus was effective to complete the mitral isthmus block line.

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