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Biomedical subjects

S D Colan

Publications and source records attributed to S D Colan.

At least 127 records · Page 7Linked to original sources
PubMed1988

Echocardiographic diagnosis of fetal heart defects in mid trimester.

One hundred and thirty five consecutive fetuses of between 16 and 23 weeks' gestation that were considered to be at high risk of having structural heart defects were examined prospectively to determine the reliability of echocardiography for diagnosing such defects in mid trimester. Each echocardiogram was done in a standard manner and cardiac anatomy was analysed segmentally. Twelve fetuses were excluded from analysis because of lack of follow up. Of the remaining 123 fetuses, 109 had no evidence of heart disease when followed up. In this group the prenatal echocardiogram was normal in 105 and technically inadequate in four; thus there were no false positive diagnoses of heart disease in fetuses subsequently shown to have normal hearts. Fourteen had heart defects at follow up. The serious defect was correctly diagnosed prenatally in 10 of 14 cases, whereas in the other four the prenatal echocardiogram was considered normal. Some errors were made in diagnosing associated segmental defects particularly if the heart disease was complicated. Therapeutic abortion was carried out in seven cases; in five of the fetuses the prenatally diagnosed heart defect was the sole or an important contributing reason for the abortion. We conclude that echocardiography is a reliable method for diagnosing many heart defects in the mid trimester.

Echocardiography↗
PubMed1988

Midterm results after the arterial switch operation for transposition of the great arteries with intact ventricular septum: clinical, hemodynamic, echocardiographic, and electrophysiologic data.

Although the short-term results of atrial level repair of transposition of the great arteries (TGA) are satisfactory, longer follow-up has disclosed a significant incidence of systemic right ventricular dysfunction and rhythm disturbances. The arterial switch operation (ASO) may represent a major improvement by restoring the left ventricle as the systemic ventricle and avoiding extensive atrial surgery. We have prospectively evaluated 49 consecutive survivors of ASO for TGA with intact ventricular septum (IVS) by clinical examination, echocardiography, cardiac catheterization, ambulatory electrocardiographic monitoring, and invasive electrophysiologic studies. The mean length of follow-up has been 29 +/- 14 (SD) months after surgery. All children are currently asymptomatic and on no medications. Severe supravalvular pulmonary stenosis (greater than 60 mm Hg) was present in five children, all of whom have undergone reoperation. No patient has severe supravalvular aortic obstruction. Mild degrees of supravalvular pulmonary or aortic obstruction have not progressed. Seven children (14%) have trivial or mild aortic regurgitation. Two children have proximal occlusion of the left anterior descending coronary artery with adequate retrograde collateral perfusion. One child had an electrocardiographic pattern of inferior myocardial infarction without evidence of ventricular dysfunction. Systemic (left) ventricular function is normal as measured by end-diastolic pressure (mean 7 +/- 6 mm Hg), ejection fraction (mean 68 +/- 6%), end-diastolic volume (mean 101 +/- 22% of predicted normal), and cardiac index (mean 4.7 +/- 1.3 liters/min/m2). Only one patient has sinus node dysfunction. There have been no late deaths. These early results are encouraging. We conclude that the arterial switch operation is currently the procedure of choice for neonates with TGA and IVS.

Cardiac Catheterization↗
PubMed1988

Myocardial performance after arterial switch operation for transposition of the great arteries with intact ventricular septum.

Left ventricular dimensions, wall thickness, wall stress, and indexes of afterload, preload, contractility, and early diastolic function, as well as regional wall motion, were determined by echocardiographic methods in patients with transposition of the great vessels after arterial switch operation and in age-matched normal controls. In patients evaluated early after surgery, body surface area-adjusted left ventricular dimensions were smaller, and wall thickness was increased compared with controls. Ventricular performance (fractional shortening) was normal in most patients but was abnormally low in 10%. Nevertheless, contractility was normal or augmented in all subjects, with a mean value higher than the control group. The reduction in systolic function was related to altered loading conditions with a combination of reduced afterload and preload combined with augmented contractility. These altered myocardial mechanics appeared to be secondary to routine therapy with digitalis and diuretics. Diastolic function was also normal with differences in the rate of peak filling and rate of wall thinning entirely attributable to differences in ventricular size and function, and normalized indexes of diastolic function were not different between patients and controls. Patients evaluated late after repair were found to have normal regional wall motion with no evidence to suggest regional dysfunction as might be seen with regional ischemia. Ventricular size, wall thickness, systolic function, afterload, preload, contractility, and early diastolic function were indistinguishable from control values. Indexes of diastolic function demonstrated the same relation to age, body surface area, and ventricular size and function in both patients and controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Anastomosis, Surgical↗
PubMed1987

Quantitative applications of Doppler cardiography in congenital heart disease.

Doppler ultrasound has rapidly become a valuable tool in the noninvasive investigation of cardiac hemodynamics. Although based on secure principles, accurate application of this methodology to quantitative measurements necessitates a thorough understanding of both Doppler physics and instrumentation. Over the past several years a large body of clinical and animal data verifying the accuracy of Doppler determination of pressure and flow data at various sites in the cardiovascular system, as well as the potential sources of error in acquisition and interpretation of blood velocity recordings, has been published. Quantitative use of Doppler in congenital heart disease, with emphasis on limitations of existing studies and issues particular to this patient population, is reviewed.

Child↗
PubMed1987

Physiologic hypertrophy: effects on left ventricular systolic mechanics in athletes.

Physiologic hypertrophy resulting from intense athletic participation has been reported to result in normal, reduced and augmented overall left ventricular performance. Rather than representing true differences in left ventricular contractility, these data may reflect the variable degree of ventricular dilation and increased wall thickness that occur with different types of exercise. As such, the resultant altered loading conditions may diminish the ability of the usual indexes of left ventricular function to accurately assess the left ventricular contractile state. Therefore, three groups of elite athletes with distinct patterns of myocardial hypertrophy were investigated utilizing recently developed load-independent contractility indexes. Age-matched control subjects (n = 33) were compared with 11 swimmers, 11 long-distance runners and 11 power lifters. Rest echocardiogram, phonocardiogram and calibrated carotid pulse tracing were used to calculate left ventricular dimensions, wall thickness, mass, fractional shortening, velocity of shortening and mean, peak and end-systolic wall stresses and the stress-time and minute stress-time integrals. Compared with control subjects, all athletes had increased left ventricular mass, even when values were normalized for body surface area. Runners had a dilated left ventricular and normal wall thickness, swimmers had a mildly dilated ventricle with increased wall thickness and power lifters had normal cavity size with markedly increased wall thickness. Peak systolic wall stress was normal in runners and swimmers and reduced in power lifters, whereas end-systolic stress was low in swimmers and power lifters and normal in runners. The minute stress-time integral, a measure of myocardial oxygen consumption, was normal in runners and swimmers but was significantly reduced in lifters.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Biological↗
PubMed1987

Left ventricular mechanics and contractile state in children and young adults with end-stage renal disease: effect of dialysis and renal transplantation.

The potential existence of a specific uremia-associated myocardial depressant factor was explored by evaluating nine pediatric subjects (3 to 21 years) without evidence of coronary artery disease or long-standing hypertension 1) before entering a dialysis program, 2) while undergoing a long-term dialysis regimen, and 3) after successful renal transplantation. Myocardial contractility was quantitated with load-independent indexes using the end-systolic pressure-dimension relation (Emax) and the relation of rate-corrected velocity of shortening to end-systolic wall stress. Myocardial loading status was determined by the direct measurement of afterload (end-systolic wall stress) and the functional quantitation of preload (differences between the relation of fractional shortening and velocity of shortening to end-systolic stress). Most patients (55%) were found to have abnormal ejection phase indexes of ventricular function either before or after entry into dialysis. However, contractility was normal in all subjects at each of their evaluations, and no change in contractility was found after dialysis or transplantation. Loading status was highly variable and usually abnormal before transplantation and accounted entirely for the abnormalities of fractional shortening and velocity of shortening. Transplantation invariably resulted in normalization of loading status and ejection phase indexes of ventricular function. In these children and young adults with uremia, abnormal ejection phase indexes of ventricular function were frequent and caused by associated abnormalities in ventricular loading. Contractility, however, was normal and no evidence of a uremia-associated myocardial depressant was found.

Adolescent↗
PubMed1987

Regional and global left ventricular function in infants with anomalous origin of the left coronary artery from the pulmonary trunk: preoperative and postoperative assessment.

Anomalous origin of the left coronary artery from the pulmonary trunk (ALCA) remains a diagnostic as well as a therapeutic problem. The purposes of this study were: (1) to analyze left ventricular mechanics, including regional wall motion, in infants with ALCA, (2) to determine if the pattern of wall motion in infants with ALCA distinguishes these patients from those with congestive cardiomyopathy of other causes, and (3) to evaluate the potential for recovery of left ventricular function after successful restoration of a dual coronary artery system. Left ventricular mechanics were studied before and serially after surgery in six infants (2 to 13 months old) with ALCA. Fifteen age-matched normal subjects and seven age-matched patients with idiopathic congestive cardiomyopathy were also studied for comparison. Preoperatively, the end-diastolic volume in infants with ALCA was about four times larger than normal and did not differ from that in infants with CM; the myocardial volume was also about three times larger than normal, similar to that in the patients with CM. The myocardial volume/end-diastolic volume ratio was extremely low in patients with ALCA and in those with CM. The infants with ALCA did not exhibit specific segmental wall motion abnormalities but rather had global hypokinesis indistinguishable from that in the patients with CM. After successful repair, end-diastolic volume index rapidly decreased, reaching near normal values by 7 to 22 months after surgery, while myocardial volume index decreased at a slower rate, leading to an early phase of "overshoot hypertrophy," but reaching normal values by 7 to 22 months after surgery.+

Cardiomyopathy, Dilated↗
PubMed1987

Diagnosis of coronary artery anatomy by two-dimensional echocardiography in patients with transposition of the great arteries.

With the increasing popularity of the Jatene procedure for the treatment of common or D-transposition of the great arteries (D-TGA), the preoperative definition of coronary artery anatomy in D-TGA has assumed great importance. Consequently, the reliability of two-dimensional echocardiography for determining the coronary artery anatomy was studied in 32 infants with D-TGA. Surgical observation of the coronary anatomy was used to assess the accuracy of the echocardiographic diagnosis. The coronary arteries were visualized in 29 of 32 patients (90%), predominantly with the use of parasternal and apical views. In the three remaining patients visualization of the coronary arteries was inadequate to allow determination of their anatomy. The coronary artery anatomy was correctly predicted in 25 of the 29 patients in whom the coronary arteries were visualized. The anatomic patterns included usual coronary anatomy for D-TGA (n = 16), left circumflex coronary from the right coronary artery (n = 6), single right coronary artery (n = 1), single left coronary artery (n = 1), and inverted origin of the coronary arteries (n = 1). The errors in the remaining four patients were (1) false-negative diagnosis of origin of the left circumflex coronary from the right coronary artery (n = 1); (2) false-positive diagnosis of origin of the left circumflex coronary from the right coronary artery (n = 1), and (3) diagnosis of origin of the left circumflex coronary from the right coronary artery when the correct diagnosis was single right coronary artery (n = 2).(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Vessels↗
PubMed1987

Left ventricular mechanics in the normal newborn.

The transition from fetal to neonatal circulatory status is accompanied by marked alteration in relative right and left ventricular systolic and diastolic pressure. These alterations would be expected to influence both global and regional performance of the left ventricle. To address this issue, sequential two-dimensional echocardiographic studies were performed in normal newborns during the first days of life. Global and regional left ventricular wall motion were quantified by computer digitization with the use of an automated edge detection algorithm and a floating-center-of-mass model. Comparison was made with a control group of normal infants and young children and the sequential change over the first 5 days of life was assessed. Newborns were found to have a circular left ventricular configuration at end-diastole beginning on day 1. At end-systole, however, there was significant left ventricular distortion due to septal flattening, which persisted until day 3 and resolved entirely by day 5 of life. Regional wall motion analysis demonstrated a corresponding augmentation of septal and contralateral left ventricular free wall systolic movement during the first days of life, with a normal pattern attained by day 4. Due to the nonhomogeneity of the left ventricular wall motion in the first few days of life, standard single-dimension shortening fraction provided an unreliable measure of global left ventricular performance before day 4. Thus, systolic right ventricular hypertension at a level sufficient to distort the left ventricular configuration is present until day 4 or 5 of life, resulting in altered left ventricular regional wall motion. As a result, usual M mode echocardiographic assessment of left ventricular function is unreliable in this age group.(ABSTRACT TRUNCATED AT 250 WORDS)

Child↗
PubMed1986

Two-dimensional echocardiographic anatomy in crisscross heart.

The anatomy of crisscross heart was studied in 14 patients, aged 2 days to 26 years, using 2-dimensional (2-D) echocardiography. The visceroatrial situs was solitus in all 14 patients. Crossing of the atrioventricular (AV) valves could be seen in each case by scanning in a subxiphoid or apical 4-chamber view. The subpulmonary infundibulum was deficient in 13 of the 14 patients, resulting in approximation of the pulmonary and tricuspid valves. Subpulmonary stenosis, seen in 11 patients, resulted from proximity of the infundibular septum, the tricuspid valve and the subpulmonary infundibular free wall. A subaortic infundibulum, present in all cases, was well developed in 13 patients, who had malposition of the great arteries, and was short in 1 patient, with nearly normally related great arteries. In cases that conformed to the inverse loop rule (segmental combination (S,D,L) or (S,L,D)), the pulmonary valve was posterior to the tricuspid valve and wedged between the AV valves. In 3 patients (double outlet right ventricle (S,D,L)) the mitral valve straddled into a large, left-sided subaortic infundibulum. In both patients with arterial malposition who did not follow the inverse loop rule, the pulmonary trunk was anterior to the tricuspid valve and well separated from the mitral valve. In patients with crisscross heart the ventricles appeared to have been rotated about their long axes without concomitant motion of the AV valve anuli, producing actual crossing of the ventricular inflow tracts. The right ventricular sinus was significantly smaller and the infundibulum significantly larger in the patients with crisscross heart than in age-matched control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1986

Cardiac output estimates in the pediatric intensive care unit using a continuous-wave Doppler computer: validation and limitations of the technique.

We compared the cardiac index obtained by means of a continuous-wave Doppler computer with simultaneous thermodilution measurements in 25 children in the pediatric intensive care unit (40 observations). The aortic diameter was measured at various levels to determine which provided the best measure of cardiac index. The Doppler measurements were performed independently by a physician trained in Doppler cardiography and by a nurse with no experience in echocardiography. Both the nurse and physician obtained high-quality flow velocity recordings in all patients in a mean time of 5 minutes or less. Cardiac index and total systemic vascular resistance measured by means of Doppler and thermodilution techniques were highly correlated (r = 0.86 and r = 0.93, respectively). The highest correlation was obtained when Doppler cardiac index was computed by means of the internal diameter measured at the aortic anulus. There was no significant difference between the nurse's and physician's measurements. We conclude that cardiac index can be accurately determined in the pediatric intensive care unit by means of continuous-wave Doppler computer, even when operated by personnel not trained in Doppler cardiography.

Cardiac Output↗
PubMed1986

Right ventricular systolic time intervals: comparison of echocardiographic and Doppler-derived values.

Although the clinical utility of right ventricular (RV) systolic time intervals (STI) has been well documented, their use is at times limited by an inability to obtain adequate M-mode echocardiographic images of the pulmonary valve. Therefore the relationship between the pulmonary artery Doppler flow tracing and the timing of pulmonary valve opening and closure was investigated to determine if the more readily available Doppler recording could be utilized for determining RV STIs. We compared RV preejection period (PEP), ejection time (VET), and PEP/VET ratio derived from the pulsed Doppler frequency-time curve recorded in the main pulmonary artery with measurements from a simultaneously recorded M-mode pulmonary valve echocardiogram (Echo). The nadir of the late systolic flow reversal, rather than the point at which the frequency spectrum crosses the zero baseline, correlated best with the point of pulmonary valve closure. By the use of this method for determining end-systole, all three Doppler-derived measurements were highly correlated with the values from the pulmonary valve echocardiogram: PEPEcho = 1.01 PEPDoppler - 3.1 (r = 0.990, S.E.E. PEPEcho = 2.7 msec); VETEcho = 0.98 VETDoppler + 10.2 (r = 0.998, S.E.E. VETEcho = 3.3 msec); (PEP/VET)Echo = 0.95 (PEP/VET)Doppler + 0.007 (r = 0.980, S.E.E. (PEP/VET)Echo = 0.012 msec). The Doppler velocity-time curve provides accurate measurement of RV STIs that can be recorded with relative ease compared with the pulmonary valve echocardiogram. This expanded availability of RV STIs permits an improved ability to investigate the hemodynamic determinants of these indices and their relation to the status of the pulmonary vasculature and right ventricular performance.

Adolescent↗
PubMed1986

Obstruction of right ventricular inflow and outflow in corrected transposition of the great arteries (S,L,L): two-dimensional echocardiographic diagnosis.

Obstruction of systemic ventricular inflow and outflow is considered uncommon in corrected transposition of the great arteries (S,L,L). Between 1979 and 1985, 42 patients with corrected transposition and two ventricles and atrioventricular valves underwent two-dimensional echocardiography. Obstruction of right ventricular inflow and outflow was present and diagnosed by two-dimensional echocardiography in 5 of the 42 patients. A supratricuspid stenosing ring, recognized in the apical or subxiphoid four chamber view as a bright, linear structure on the left atrial side of the tricuspid valve, occurred in two patients. Subaortic obstruction due to infundibular hypertrophy with or without displaced muscle bundles was seen in three patients. Subxiphoid long- and short-axis views and parasternal long-axis views best displayed these features. Aortic coarctation was present in four cases and could be diagnosed using modified suprasternal notch views. Thus, systemic ventricular inflow and outflow obstruction may be more common in corrected transposition than previously believed (occurring in up to 10 to 15% of patients). The mechanisms producing the obstruction appear to be characteristic of the left atrium and right ventricle irrespective of location or connections. Echocardiography appears to be an excellent technique for diagnosing these associated lesions in corrected transposition.

Aortic Coarctation↗
PubMed1985

Two-dimensional echocardiographic estimation of right ventricular area change and ejection fraction in infants with systemic right ventricle (transposition of the great arteries or hypoplastic left heart syndrome).

A reproducible, noninvasive method for estimating right ventricular (RV) function would greatly facilitate evaluation of infants in whom the RV supplies the systemic circulation. Therefore, 2-dimensional echocardiographically derived parameters, RV area-change fraction and RV ejection fraction (EF), were evaluated in 19 preoperative infants (age 1 to 30 days, mean 7 days), 12 with hypoplastic left heart syndrome and 7 with transposition of the great arteries. The area enclosed by the RV was measured in both a subxiphoid long-axis (coronal plane) and short-axis (parasagittal plane) view. From these measurements end-systolic and end-diastolic volumes were derived using Simpson's rule and the EF was calculated. The total area change fraction was calculated as the average of the long and the short-axis area change fraction. Similar measurements were made independently from biplane cineangiograms obtained within 3 days of the echocardiogram. The echocardiographically derived EF and area-change fraction were compared with the angiographic EF using linear regression analysis. The echocardiographic EF (mean 49 +/- 11) correlated well with the angiographic EF (mean 51 +/- 12, r = 0.84). The echocardiographic area-change fraction was somewhat less closely correlated with the angiographic EF (r = 0.79). Comparing short- and long-axis area-change fraction to echocardiographic EF, the short-axis measurements were better correlated than long-axis measurements (r = 0.86 and 0.75, respectively). (ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac Output↗
PubMed1985

Effects of loading conditions and contractile state (methoxamine and dobutamine) on left ventricular early diastolic function in normal subjects.

The influence of changes in preload, afterload and contractile state on left ventricular (LV) filling characteristics were examined. Normal subjects underwent echocardiographic determination of the peak rates of LV dimension change and wall thinning and their respective timing at rest, after preload augmentation with dextran, during increased afterload with methoxamine and during inotropic stimulation by dobutamine. These 2 peak velocities and their timing in diastole correlated well with each other and responded similarly to interventions. Increased preload resulted in higher peak velocities of dimension change and wall thinning, without changing the time in diastole at which they occur. Both peak velocities moved later into diastole with higher afterload; however, the overall change in magnitude was variable and without statistical significance. Inotropic stimulation resulted in faster rates of peak dimension change and wall thinning, which occurred at an earlier point in diastole. Examination of various measures of LV size and function over a wide range of preload and afterload conditions under a constant contractile state revealed a complex set of relations. The ratio of wall thickness-to-dimension at end-diastole showed the most significant relation to the peak rate of dimension change, whereas peak thinning was best correlated with fractional wall thickening. Both velocities were also significantly but more weakly related to other variables of systolic function. The timing of these peak velocities correlated most closely with the end-systolic wall stress and heart rate. Thus, LV filling and wall thinning depend in a complex fashion on loading conditions, heart rate and contractile state.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗