An apparent lack of internal consistency is pointed out in a recent fitting by Morante et alof an expression for the multiphonon capture cross section to the experimental electron capture cross section for the A and B centres in GaAs due to Henry and Lang. It is found that the Huang-Rhys factor derived ab initio from the model of Morante et a1 is 0.49 for the B centre in contrast to the value 5.03 needed to fit the experimental data using the same model. Possible shortcomings of the model are discussed.
Three LVSTI are conventionally measured:'`3 total electromechanical systole (QS2), the left ventricular ejection time (LVET), and the pre-ejection period (PEP). QS2 is defined from the onset of ventricular depolarization (Q wave of ECG) to the initial high frequency vibraton of the aortic component of the second heart sound. LVET is derived from the onset of the upstroke of the carotid pulse to the incisural Received June 19, 1974; revision accepted for publication October 10, 1974. 304 notch, and PEP is obtained indirectly by subtracting LVET from QS2. To date, noninvasive assessment of right ventricular performance by measurement of STI has not been possible because of the inability to define accurately the onset of right ventricular ejection. The purpose of this study was to demonstrate that right, as well as left, ventricular STI can be measured noninvasively by the use of ultrasound. In addition, patients with transposition of the great arteries (TGA) were studied because they have a unique reversal of systemic and pulmonic vascular circuits, which permitted evaluation of the effect of this reversal on RV and LVSTI. MethodsThe echocardiograms were obtained with a Hoffrel 101 ultrasonoscope. Simultaneous strip chart recordings of the echocardiogram, phonocardiogram, carotid pulse tracing and ECG were obtained with a Cambridge Multichannel Physiological Recorder, Amplifier Type 72352.The ECG lead which most clearly demonstrated early ventricular depolarization, usually the Q wave, was chosen for timing the onset of electrical systole. The phonocardiogram was recorded with a piezo-electric, high impedance microphone having a frequency band of 100 to 600 cycles per second. Recordings were made at the base of the heart in the higher frequency sound spectrum.The carotid pulse measuring equipment consisted of an electronic amplifier driven by a piezo-electric pulse transducer. The sensing device is a plastic cone connected
Serial assessment of the status of the pulmonary vascular bed requires repeat cardiac catheterization. We have demonstrated that right ventricular systolic time intervals (RVSTI) may be measured from the pulmonary valve echo. The right ventricular ejection time (RVET) and right pre-ejection period (RPEP) were measured in 45 normal patients. The RVET and RPEP decreased with increasing heart rate but increased with age. The RPEP/RVET, however, was uninfluenced by either age or heart rate. The RPEP/RVET was, therefore, determined from the pulmonary valve echo in 64 patients with congenital heart disease who underwent cardiac catheterization. Increased pulmonary artery diastolic pressure (PADP), pulmonary vascular resistance (PVR) and mean pulmonary artery pressure (MPAP) resulted in an increased RPEP/RVET. The use of the RPEP/RVET permitted the serial echographic evaluation of the pulmonary vascular bed in selected patients; marked elevation of the ratio indicated the presence of pulmonary hypertension.pATIENTS WITH LARGE left-to-right shunts, such as ventricular septal defect (VSD), patent ductus arteriosus (PDA), atrioventricular canal (AVC), and atrial septal defect (ASD), as well as patients with transposition of the great vessels (TGV), with and without a VSD, may develop hypertensive pulmonary vascular disease. -4 It has been shown that patients with severe pulmonary vascular obstructive disease complicating their congenital heart lesion are high risk surgical candidates and survive longer if corrective surgery is not undertaken.5' 6 It is, therefore, important to select patients for surgery prior to the development of advanced pulmonary vascular changes.Patients with congenital heart disease, who are at risk to develop pulmonary vascular disease, may require repeat cardiac catheterization to permit serial evaluation of pulmonary vascular resistance (PVR) and pulmonary artery diastolic pressure (PADP) in order to determine the timing of corrective surgery.7The advantage of a noninvasive technique that would permit the serial assessment of the pulmonary vascular bed and indicate the presence of pulmonary hypertension is easily appreciated.To date, the noninvasive assessment of the pulmonary vascular bed has been technically difficult. The purpose of this study was to observe the relationship of PADP, PVR, and mean pulmonary artery pressure (MPAP) to the RVSTI derived from the pulmonary valve echo, and to determine if alteration of the ratio RPEP/RVET permits the noninvasive assessment of PADP, PVR, and MPAP. MethodsThe echocardiograms were obtained with a Hoffrel lOlB ultrasonoscope. Strip chart recordings of the echocardiograms were obtained with a Cambridge Multichannel Physiological Recorder, Amplifier Type 72352.A 5.0 MHz, 1/4 inch diameter, unfocused transducer was used to record the pulmonary valve echo in infants less than six months old. In older children a 2.25 MHz, 1/4 inch diameter transducer, focused at 5 centimeters, was employed. The pulmonary valve echo was recorded from the second or third inte...
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