Seiki Nobe

Gender differences in ventricular repolarization: Terminal T wave interval was shorter in women than in men

NAKAGAWA, M., et al. : Gender Difference in Ventricular Repolarization: Terminal T Wave Interval was Shorter in Woman than in Men. The incidence of sudden death is lower in women than in men, although women have a longer QT interval and are more prone to develop torsades de points than men. It has been recently proposed that the time interval between the apex and end of the T wave (Ta‐e) represents the transmural dispersion of ventricular repolarization. Gender and age differences in Ta‐e interval have not been fully assessed previously. Standard surface 12‐lead ECGs recorded in 760 healthy subjects (382 women, 0–88 years of age) were studied. The intervals from j‐point to the apex of the T wave (JaT) and to the end of the T wave (JeT) were measured in lead V5 in each ECG and corrected by preceding RR intervals using the formula of Bazett (JaTc and JeTc). The Ta‐e and Ta‐e/JeT ratio were also evaluated. Both JaTc and JeTc intervals were significantly longer in women aged > 20 years than in men of the same age(P < 0.0001). The difference was due to shortening of these intervals after puberty in men. However, the Ta‐e interval was significantly shorter in women than in men(P < 0.05)and subsequently the Ta‐e/JeT ratio was significantly smaller in women than in men (P < 0.0001). The results showed gender differences in the Ta‐e interval and JaTc and JeTc intervals in healthy adults, and suggest that the small transmural dispersion of repolarization in women, in spite of the long JaTc and JeTc intervals, might be a beneficial antiarrhythmic property. (PACE 2003; 26[Pt. I]:59–64)

Dynamics of T-U wave in patients with idiopathic ventricular tachycardia originating from the right ventricular outflow tract

Postextrasystolic U wave augmentation is observed in patients with long QT syndrome and those with organic heart disease. This phenomenon is considered a marker of increased risk of arrhythmia. However, the characteristics of the U wave have not been evaluated in patients with idiopathic VT originating from the right ventricular outflow tract (RVOT‐VT). The present study evaluated the dynamic change in the T‐U wave in patients with RVOT‐VT. Holter ECGs obtained from 14 patients with RVOT‐VT and 11 healthy control subjects were analyzed. The amplitude of T and U waves (Tamp and Uamp) and preceding RR intervals were measured during stable sinus rhythm (rate dependent change) and in the postextrasystolic sinus complex (pause dependent change). Uamp correlated negatively and significantly with the preceding RR interval in 13 (93%) RVOT‐VT patients but in only 2 (18%) control subjects. The average value of the slope of the Uamp/RR relationship was negative (−0.22 ± 0.10 mV/s) in the RVOT‐VT group, but was positive (0.04 ± 0.07 mV/s, P < 0.001) in the control group. Pause dependent U wave augmentation was observed in 12 (86%) of 14 patients. Increased frequency of consecutive preceding premature ventricular contractions (PVCs) was associated with a larger postextrasystolic Uamp. PVC or the first ventricular beat of VT arose from near the peak of augmented U waves. The dynamic changes in the T‐U wave were observed in patients with RVOT‐VT. Further investigations are required to elucidate the precise role of the U wave in arrhythmogenesis in those patients. (PACE 2004; 27:148–155)

Patients with mild hypertensive heart disease and left ventricular outflow tract obstruction: treatment with angiotensin II antagonists.

Systolic anterior motion of the mitral leaflet (SAM) combined with obstruction at the left ventricular (LV) outflow tract is often observed on echocardiography in elderly hypertensive patients with severe concentric LV hypertrophy. We experienced, however, two patients with mild hypertension who had an ejection systolic murmur, SAM, and LV outflow tract obstruction with a pressure gradient of 46 and 45 mmHg, respectively, despite very mild symmetric hypertrophy of LV wall (12 mm) by echocardiography. Treatment with angiotensin II type 1 receptor blocker improved intraventricular obstruction and LV hypertrophy in both patients. Left ventricular outflow tract obstruction should be suspected in hypertensive patients with mild LV hypertrophy, particularly in those with an ejection systolic murmur. Angiotensin II antagonists could be considered as the treatment of choice for such patients.

Malignant neurocardiogenic vasovagal syncope associated with chronic exaggerated vagal tone.

NAKAGAWA, M., et al.: Malignant Neurocardiogenic Vasovagal Syncope Associated with Chronic Exaggerated Vagal Tone. A head‐up tilt test was performed in a 23‐year‐old woman with a history of two syncopal episodes. The patient developed abrupt syncope with 48 seconds of sinus arrest. Analysis of the high frequency (HF) power of heart rate variability over 24 hours before and after metoprolol therapy showed a significantly elevated HF power in this patient compared to age– and sex‐matched healthy subjects. It is suggested that an exaggerated resting vagal tone might be associated with the pathogenesis of prolonged asystole in our patient.