Backgrounds : Ventricular tachycardia (VT) in patients with reduced left ventricular ejection fraction (LVEF) leads to sudden death. Mortality of patients with maintained LVEF has not been fully elucidated. We evaluated the relationship between clinical outcome and the inducibility of VT by electrophysiological study (EPS) in patients with comparatively maintained LV function.
Methods and Results : We retrospectively investigated consecutive 65 patients (55 men, 52±16 years) with structural heart disease, sustained monomorphic VT and LVEF≥35%who underwent EPS or CA between 2003 and 2009, including 21 individuals with ischemic heart disease, 13 with dilated cardiomyopathy, 3 with hypertrophic cardiomyopathy, 6 with sarcoidosis, 17 with ARVC, and 5 after operation for tetralogy of Fallot. ICD was implanted in 36 patients (55%) . During 43±21 months of follow-up, no patients died of any cause. Non-inducibility of VT at the end of procedures related to lower VT recurrence than patients with inducible VT (19%vs. 45%, p=0.028, log-rank) . Among 44 patients who underwent CA, non-induction related to less VT recurrence (18%vs. 55%, p=0.025, log-rank) . VT inducibility after CA was an independent predictor of VT recurrence (hazard ratio 3.38, p=0.04, Cox regression) .
Conclusions : Patients with VT and comparatively maintained LVEF had a favorable prognosis even with VT recurrence. Non-VT-inducibility at EPS or after CA demonstrated reduced risk of VT recurrence.

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A 70-year-old man, who had suffered from myocardial infarction 25 years ago, admitted with- ventricular tachycardia (VT) . Upon further examination, he was found to have 2 vessel disease including total occlusion of the left anterior descending artery and the left ventricular apical aneurysm with multiple thrombi. He needed coronary bypass grafting and removal of the thrombi. We planned to treat VT during the operation. After Off-pump coronary artery bypass grafting, cardio-pulmonary bypass was started. Apical thrombi were removed through the incision of the aneurysm, and the heart was restarted by cardioversion. After rewarming to normal body temperature, VTs were induced by left ventricular extrastimulation. By endocardial mapping with a 20-electrode ring catheter, the earliest activation sites and the neighbor area, where diastolic potentials were recorded, were marked by a color marker. Linear ablations by a monopolar radiofrequency device were performed at the marked area 3 times at a setting of 70 degrees centigrade for 60 seconds. After the procedure, VT could not be induced by extra- and burst-cardiac stimulation. Finally, left ventriculoplasty was performed. VT has not recurred in the 20 months since the surgery.

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Cardiac arrhythmias, sinus node dysfunction (SND) in particular, are common in orthotopic heart transplantation (OHT) recipients. In the Lower and Shumway's technique (biatrial anastomosis) , which has been the most frequently utilized, the patient after OHT has two sinus nodes in the right atria connected to each other but electrically isolated by surgical suture lines. The recognition of P waves from both donor and recipient atria in the electrocardiogram (ECG) is occasionally troublesome and therefore the erroneous diagnosis of atrioventricular (AV) block can occur, particularly in patients with SND.
Here, we present a 31-year-old man after OHT manifested by relative bradycardia in the late postoperative period. Both a coronary angiogram and an endomyocardial biopsy at the same time from the right ventricle revealed no abnormal findings. At the cardiac catheterization, a temporary pacing lead was inserted and placed under the diagnosis of transient marked bradycardia due to &lsquocomplete AV block&rdquo. Electrophysiologic study (EPS) showed normal AV conduction between the donor sinus node impulse and ventricular depolarization, and markedly abnormal donor sinus node function. In the present case, sinus arrest of the donor atria produced the recording of dissociated P wave from the recipient atrial remnant and QRS complex by the donor AV junctional escape rhythm in a pattern mimicking complete AV block. When examining bradycardiac ECGs in patients with OHT, sufficient care should be taken to differentiate the donor and recipient P waves in order to avoid misinterpretation of the rhythm, and EPS can be a potent diagnositic tool for a precise diagnosis.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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[in Japanese]

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