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Autosomal dominant inheritance of thoracic aortic aneurysms and dissections occurs in subjects with Marfan syndrome, which results from mutations in the FBN1 gene on chromosome 15. A second chromosomal locus on 3p24-25 has been identified for a Marfan-like condition with thoracic aortic aneurysms. We describe here 6 families with multiple members with thoracic aortic aneurysms and dissections in the absence of the ocular and skeletal complications of Marfan syndrome. Medical records and autopsy reports on affected subjects in families with multiple members with thoracic aortic aneurysms and dissections were reviewed. Subjects in these families at risk for developing aortic disease underwent echocardiography to evaluate the aorta. The pattern of inheritance of thoracic aortic aneurysms and dissections was autosomal dominant in these families. Most affected subjects presented with aortic root dilatation or acute type I dissection, but the age of onset of disease was variable and there was decreased penetrance of the disorder. In 2 of the families, the syndrome was not linked to FBN1 or 3p24-25. Familial thoracic aortic aneurysm and dissection is an autosomal dominant condition with marked variability in the age of onset of aortic disease and decreased penetrance, making identification of affected subjects difficult. This condition is not due to mutations in the FBN1 gene or the unidentified gene on 3p24-25. [ABSTRACT FROM AUTHOR]

Introduction: Damped sine wave pulses have been used for nearly 50 years in transthoracic defibrillation systems. The purpose of this study was to determine whether damped sine wave pulses have a role in implantable defibrillators., Methods and Results: In 21 survivors of cardiac arrest, we prospectively compared defibrillation efficacy of a standard truncated capacitor (RC) monophasic pulse with a damped sine wave inductor-capacitor (LRC) pulse using a right ventricular-left ventricular epicardial patch-patch electrode system. The RC pulse was a standard 65% tilt monophasic waveform generated from a 120 mu F capacitor. The LRC pulse was designed to simulate the waveform currently used in transthoracic defibrillators and was generated by passing the charge stored on a 40 mu F capacitor through a 37-mH inductor. Capacitor voltage, peak delivered voltage, peak delivered current, discharge pathway resistance, delivered energy, and stored energy were compared for the two waveforms at the defibrillation threshold. There was no difference in defibrillation efficacy for the two waveforms. Peak delivered voltage was similar at the defibrillation threshold: 313 +/- 101 V for the RC pulse and 342 +/- 119 V for the LRC pulse (P = 0.16). Similarly, no differences were found in defibrillation threshold peak delivered current: 8.6 +/- 2.5 (RC) versus 9.3 +/- 2.7 (LRC) amperes (A) (P = 0.20); discharge pathway resistance: 37 +/- 11 (RC) versus 38 +/- 13 (LRC) omega (P = 0.71); delivered energy: 7.0 +/- 4.5 (RC) versus 7.0 +/- 4.0 (LRC) joules (J) (P = 0.88); and stored energy: 8.7 +/- 5.7 (RC) versus 9.8 +/- 5.4 (LRC) J (P = 0.35). Although both waveforms performed the same, it was necessary to use substantially higher stored voltages with the damped sine wave delivery system than with the truncated waveform delivery system: 356 +/- 110 V for the RC pulse and 675 +/- 192 V for the LRC pulse (P < 0.0001)., Conclusion: This study demonstrates that RC monophasic pulses provide equally effective epicardial defibrillation as LRC pulses with respect to delivered voltage and current and stored and delivered energy. However, in order for LRC pulses to provide comparable delivered voltage, current, and energy to that of RC pulses, nearly twice the voltage must be stored on the capacitor to accomplish the same task. These findings suggest that despite the nearly 50-year experience with damped sine wave pulses with transthoracic defibrillators, there is no need to begin using damped sine wave pulses for implantable defibrillators. Moreover, these data raise a question regarding the need for inductors in transthoracic defibrillators.