SUMMARY Echocardiographic data from 92 younger normal subjects (1 month to 23 years of age) and 136 older normal subjects (20-97 years of age) were pooled and analyzed to obtain prediction equations for normal echocardiographic values. Using a bivariate regression model with the assumption that variability is constant as a percentage of the expected value, we developed regression equations and graphs that allow calculation of a 95% prediction interval for several echocardiographic measurements as a function of the subject's age and either body weight or body surface area. Body weight could be substituted for body surface area with no loss of precision. Further, examination of residuals showed that the linear prediction model fit well for all ages and all echocardiographic measurements studied. The measurements were obtained using the recently published standards recommended by the American Society of Echocardiography.WE RECENTLY ANALYZED our experience with M-mode echocardiography in two groups of normal subjects." 2 One group consisted of boys and girls who ranged from 1 day to 23 years of age and the other consisted of men and women ages 20-97 years. After these data had been analyzed, the American Society of Echocardiography recommended measurement standards for M-mode echocardiography3 that differed in some respects from those we used to construct the normal graphs based on our previous studies of normal subjects.To generate normal values for echocardiographic measurements based on the new American Society of Echocardiography standards, we reanalyzed the data from the younger and older normal subjects. The new regression equations and graphs derived from this analysis are applicable to subjects of any age and have been related to both body surface area and body weight. The development of normal data based on body weight simplifies the determination of normal values because it eliminates the intermediate step of calculating body surface area. Methods Study PopulationTwo groups of normal subjects were studied. One group consisted of 92 normal subjects 1 month to 23 years of age.' Forty-five of the 92 were males and 47 were females. No subject had evidence of heart or systemic diseases. Twelve-lead ECGs and cuff blood pressure measurements were available in most patients and were found to be normal.The other group consisted of 136 adult normal subjects (78 men and 58 women) ages 20-97 years.2 No subject had a history of heart disease or hypertension, and all subjects had a normal physical examination, From the Cardiology Branch, NHLBI, NIH, Bethesda, Maryland.
SUMMARY In an attempt to define quantitatively the relation between left atrial size and atrial fibrillation, echocardiography was used to study 85 patients with isolated mitral valve disease, 50 patients with isolated aortic valve disease, and 130 patients with asymmetric septal hypertrophy. In all three groups of patients, atrial fibrillation was rare when left atrial dimension was below 40 mm (3 of 117 or 3%) but common when this dimension exceeded 40 mm (80 of 148 or 54%). In addition, when left atrial dimension exceeds 45 mm, cardioversion, while initially successful, is unlikely to produce sinus
The results of operative treatment in 83 patients with idiopathic hypertrophic subaortic stenosis (IHSS) are described. Most patients with the disease are asymptomatic, or derive satisfactory symptomatic improvement from nonoperative therapy: administration of propranolol, exerice limitation, control of arrhythmia, etc. Operation is required, however, in 10-15% of patients, those who remain severely symptomatic after nonoperative treatment or who become refractory to it. Operation relieves symptoms in IHSS by relieving obstruction to left ventricular outflow, and for a patient to be considered an operative candidate severe obstruction must be documented at left heart catheterization either under resting conditions or after provocative interventions. All 83 patients were severely incapacitated--58 in Class III and 24 in Class IV. Seventy had obstruction at rest (average gradient 96 mm Hg), and 13 had only provocable obstruction. At operation the hypertrophic interventricular septum was exposed via an aortotomy, and a vertical bar of muscle was resected between parallel myotomy incisions. There were six operative deaths (7%); no patient has died since 1970. Seven patients have died late after operation, five of them from causes unrelated to their heart disease or the operation. All surviving patients describe symptomatic improvement. Fifty-two patients with obstruction at rest preoperatively (average gradient 95 mm Hg) have been studied postoperatively: no resting gradient was evident in 47, while in the remaining five the gradient was less than 25 mm Hg. Recurrence of obstruction has never been observed at late catheterization (21 pts) or late echocardiographic examination (37 pts). Obstruction could not be provoked postoperatively in ten of the 11 patients who had large gradients only with the Valsalva maneuver or isoproterenol administration preoperatively. Obstructed and provocable obstructed patients had similar symptomatic improvement after operation. A variety of rhythm and conduction abnormalities were observed both pre and postoperatively, and these are described in detail. The results of operation in these 83 patients with IHSS demonstrate that gratifying symptomatic and hemodynamic improvement uniformly follows left ventriculomyotomy and myectomy. Relief of obstruction and amelioration of symptoms have proved to be long-lasting during postoperative observation periods extending to 14 years. Continued application of the operative procedure in properly selected patients appears to be indicated.
In order to determine normal echocardiographic values for older subjects, we studied 136 adults (78 men and 58 women, 20 to 97 years of age) without evidence of cardiovascular disease. When patients were subdivided into six age groups, progressive changes were found in mean normal values for various parameters. Specifically, when the oldest group (over 70 years) was compared with the youngest group (21-30 years), significant (p less than 0.01) increases in aortic root (22 percent) and left atrial (16 percent) dimensions, in ventricular septal (20 percent) and left ventricular free-wall (18 percent) thicknesses, and in estimated left ventricular mass (15 percent) were noted. In addition, a significant (p less than 0.01) decrease in mean mitral E-F slope (43 percent) and slight decreases in mean left ventricular systolic and diastolic internal dimensions (5 and 6 percent, respectively; p less than 0.05) were noted. Left ventricular ejection fraction and percentage fractional shortening were found to be independent of age. These data have been used to derive regression equations that are related to both age and body surface area. The regression equations can be used to calculate mean normal values and 95 percent prediction intervals for echocardiographic measurements in adults.
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