Biomedical subjects

A Kisanuki

Publications and source records attributed to A Kisanuki.

58 records · Page 4Linked to original sources

PubMed1985

[Continuous wave Doppler assessment of prosthetic valves in the mitral position: comparison of the St. Jude medical mechanical valve and the porcine xenograft valve].

To assess the opening function of prosthetic valves in the mitral position with special reference to the type and size of the valve and the years since replacement, we recorded maximum flow velocity through the mitral orifice using continuous wave Doppler echocardiography for 50 patients with mitral valve replacement and 15 normal subjects. There were 33 patients with St. Jude Medical valves and 17 with porcine xenograft valves. An ultrasonic transducer was placed over the left ventricular apex and the direction of the ultrasonic beam was positioned to be parallel with mitral flow using the Doppler audio signals. A pressure gradient was calculated from continuous wave Doppler flow velocity with a simplified Bernoulli's equation proposed by Hatle et al. The peak and mean maximum flow velocity, mean pressure gradient across the valve and the pressure half time were measured to evaluate the opening function of the prosthetic valve. The results were as follows: All four measurements were significantly larger in patients with valve replacements than in normal subjects, and were significantly increased in patients with porcine xenograft valves compared to those with St. Jude Medical valves. The opening function was well maintained in patients having larger valves than in those having smaller ones in the group of St. Jude Medical valve replacement. In patients who had porcine xenograft valve for four years or more, the opening function was decreased the more years they had been implanted. We conclude that continuous wave Doppler echocardiography is a useful noninvasive method for the quantitative assessment of the diastolic opening function of the prosthetic mitral valve.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1985

[Systolic honk in mitral stenosis: a case report].

This case report describes a mitral systolic honk originating from the mitral valve and adjacent structures in a 52 year-old woman with mitral stenosis. The patient was hospitalized because of dyspnea. Auscultation of the heart revealed a grade 3/6 apical early systolic honk accompanied by an increased first heart sound, an opening snap and a diastolic rumble. The phonocardiogram demonstrated an early systolic honk at a frequency of 115 Hz. Intensity of the honk varied on beat to beat basis, increasing in the short preceding R-R interval compared to that in the long one. The M-mode echocardiogram showed early systolic fluttering of the mitral valve and chordae tendineae at the same frequency as the honk. The two-dimensional echocardiogram showed bulging of the anterior mitral leaflet toward the left atrium in early systole. After treatment with digitalis and diuretics, the early systolic honk disappeared in beats with preceding long R-R intervals (greater than 1100 msec). In beats without the honk, systolic fluttering of the mitral valve was not observed. The genesis of the early systolic honk is analogous to that of the honk audible in mitral or tricuspid valve prolapse. The bulging of the anterior mitral leaflet into the left atrium may produce vibrations of the mitral valve leaflets and adjacent structures.

Chordae Tendineae↗

PubMed1985

[Continuous wave Doppler echocardiographic assessment of aortic stenosis and aortic regurgitation].

Twenty-four patients with aortic stenosis and 22 with aortic insufficiency were evaluated using continuous wave Doppler echocardiography (echo). Doppler echo studies were performed 48 hours before cardiac catheterization. Fifteen normal subjects served as controls. Peak velocity in the ascending aorta in aortic stenosis ranged from 2.0 to 6.0 m/sec with a mean of 3.7 m/sec, and this was significantly increased over the normal controls (mean 1.1 m/sec: 0.7-1.4 m/sec). Using the simplified Bernoulli equation (P = 4 V2, P: peak pressure gradient, V: peak flow velocity), the peak pressure gradient across the aortic valve was measured from the peak velocity in patients with aortic stenosis. The results (Y) correlated well with the peak-to-peak pressure gradient (X) between the left ventricular pressure and aortic pressure as obtained by cardiac catheterization (Y = 1.1 X +2.5, r = 0.83). Aortic regurgitation was detected by continuous wave Doppler echo in all patients with aortic insufficiency, but in only half of the patients the peak velocity could be measured (3.8 +/- 0.3 m/sec, mean +/- SD). In the remaining patients, it was difficult to measure the peak velocity, but it seemed to be greater than 3.0 m/sec. On the simultaneous recordings of the gradient between aortic and left ventricular pressures and continuous wave Doppler echo in patients with aortic regurgitation, the shape and pattern of the pressure gradient during diastole were similar to those of continuous wave Doppler echo. We conclude that continuous wave Doppler echo is a very sensitive method for diagnosing aortic stenosis and regurgitation, and it provides a quantitative assessment of the severity of aortic stenosis.

Adult↗

PubMed1984

[Detection of a shunt flow through a defect in secundum atrial septal defect by right parasternal approach using pulsed Doppler echocardiography].

Pulsed Doppler echocardiography combined with two-dimensional echocardiographic (2-DE) system was performed to detect a shunt flow through a defect in the interatrial septum (IAS) in patients with secundum atrial septal defect (ASD) utilizing right parasternal approach (RPA). RPA is a method which provides an accurate evaluation of a defect in the IAS on a 2-DE image by placing a transducer on the right of the sternum because the ultrasonic beam passes in a plane almost perpendicular to the IAS. The subjects consisted of 20 patients with ASD (25 +/- 22 yrs) diagnosed by cardiac catheterization or 2-DE with peripheral contrast material injection, and 10 cases of healthy subjects (34 +/- 18 yrs). Defects in the IAS were clearly visible in 19 patients with ASD on 2-DE images by RPA. By placing the sample volume in the center of the defect, Doppler flows could be obtained in 17 of them. In 13 with sinus rhythm, except a case of Eisenmenger syndrome, Doppler signals showed mainly a laminar flow toward the transducer (positive flow), but a transient flow of low velocity away from the transducer (negative flow) was also observed. The positive flow had its peaks in late systole and atrial systole and occasionally in mid-systole, early diastole and mid-diastole. The negative flow occurred in early systole, mid-diastole and late diastole. In a patient with Eisenmenger syndrome and tricuspid regurgitation (TR), a negative turbulent flow was observed from early systole to mid-diastole. In three patients with atrial fibrillation, Doppler signals were variable. The Doppler echogram of a patient with atrial fibrillation but no complication showed a laminar positive flow with its peaks in late systole and mid-diastole, and a negative flow in early systole. One patient with atrial fibrillation and TR had a systolic negative turbulent flow and a mid-diastolic laminar positive flow. In a patient with TR and mitral regurgitation, the Doppler echocardiogram showed a laminar positive flow throughout the entire cardiac cycle with its peaks in early diastole and mid-diastole. Doppler signals from the left atrium (LA) to the right atrium (RA) through a defect coincided in timing with the appearance of negative contrast echo from the defect to the RA on 2-DE image and signals from the RA to the LA coincided with the appearance of the contrast echo into the LA from the RA through the defect. Doppler signals disappeared after the closure of the defect in all six patients examined.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗