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Biomedical subjects

M G Sutton

Publications and source records attributed to M G Sutton.

At least 37 records · Page 2Linked to original sources
PubMed1988

Aortic regurgitation and mitral valve prolapse with Down's syndrome: a case-control study.

This case-control study was designed to determine whether aortic regurgitation (AR) and mitral valve prolapse (MVP) are specifically associated with Down's syndrome, or occur in a comparably retarded population without Down's syndrome. The 92 control subjects resided at the same institution as the 131 cases, and had mental retardation attributable to low birth weight or perinatal asphyxia. Mean (+/- SD) ages of the cases and the control group were 41 +/- 11 years compared with 40 +/- 13 years, respectively. The relative risk of AR among the cases (those with Down's syndrome) was 2.9 (95% confidence interval, 0.65-13.2; P = 0.16) and that of MVP was 3.5 (95% confidence interval, 1.2-10.2; P = 0.02). The results showed that these two valvular abnormalities are specifically associated with Down's syndrome in adults.

Adult↗
PubMed1987

High frequency of mitral valve prolapse and aortic regurgitation among asymptomatic adults with Down's syndrome.

Although cardiac anomalies are well documented among children with Down's syndrome, data on the cardiac status of adults with Down's syndrome are sparse. Therefore, we performed cardiac auscultation and Doppler echocardiographic examinations in 35 asymptomatic adults with Down's syndrome. There were 25 men and ten women; their mean age (+/- SD) was 26 +/- 8 years. Only ten subjects (29%) had normal findings on examination. The most frequent abnormal findings were holosystolic mitral valve prolapse (MVP) in 20 subjects (57%) and mild aortic regurgitation in four subjects (11%). Of the 20 subjects with MVP, five had associated tricuspid valve prolapse, but none had notable mitral regurgitation. Thus, we found that the majority of asymptomatic adults with Down's syndrome had valvular heart abnormalities. The high frequency of MVP and aortic regurgitation suggests that these lesions may be specifically associated with Down's syndrome in adults.

Adult↗
PubMed1987

Contribution of afterload, hypertrophy and geometry to left ventricular ejection fraction in aortic valve stenosis, pure aortic regurgitation and idiopathic dilated cardiomyopathy.

To investigate the relation of left ventricular (LV) afterload, hypertrophy, geometry and systolic pump function, 17 normal persons, 24 patients with aortic stenosis (AS), 20 with aortic regurgitation (AR) and 15 with idiopathic dilated cardiomyopathy (DC) were studied. Two-dimensional echograms were used to assess end-systolic meridional and circumferential stresses and their ratio, LV mass, relative wall thickness (h/R ratio) and the ratio of LV minor axis to length, used as an index of shape. Independently obtained ejection fraction (EF) was used to determine which patients had normal (EF greater than or equal to 55%) and which had depressed (EF less than 55%) pump function. Patients with AS and low EF had similar LV mass (228 vs 215 g) but larger LV cavity (5.6 vs 4.5 cm), lower h/R ratio (0.53 vs 0.73, p less than 0.01), and therefore higher circumferential stress (336 vs 268 kdyne/cm2, p less than 0.05). Compared with normal persons, patients with DC had a lower h/R ratio (0.28 vs 0.38, p less than 0.01), higher circumferential stress (362 vs 215 kdyne/cm2, p less than 0.01) and more uniform stress distribution (meridional to circumferential stress ratio 0.57 vs 0.39, p less than 0.01), implying that meridional stress overestimates effective afterload. Afterload excess and LV shape change may be important to pump function in patients with AS or DC. In contrast, in those with AR, no significant shape differences were noted, although LV mass was higher in those with low EF (279 vs 211 g, p less than 0.05). Depressed pump function may result from impaired myocardial performance in AR without afterload excess.

Adult↗
PubMed1987

Doppler echocardiographic evaluation of ring mitral valvuloplasty for pure mitral regurgitation.

Doppler echocardiographic studies were performed in 21 consecutive patients (mean age 56 +/- 11 years) to evaluate postoperative results of mitral ring anuloplasty. All patients were symptomatic and all had clinically severe isolated mitral regurgitation (MR). The origin of MR was myxomatous degeneration, coronary artery disease, rheumatic heart disease or congestive cardiomyopathy. In 20 patients ring anuloplasty was performed using the Carpentier ring and 1 patient using the Duran ring. Postoperative Doppler echocardiographic studies were performed to detect and semiquantitate residual MR by flow mapping and to identify left ventricular inflow or outflow obstruction. The severity of MR was assessed by flow mapping in the left atrium and graded from I to IV in increasing severity. Blood flow velocity spectra were recorded from the left ventricular outflow tract during systole and from the left ventricle subjacent to the mitral valve during diastole. Pressure half-time, mitral valve area and mitral valve gradient were derived from digitized mitral diastolic flow velocity spectra. After ring valvuloplasty, 9 patients had no MR and 6 had grade I, 3 grade II, 2 grade III and 1 patient grade IV MR. Peak diastolic mitral valve gradient was 8 +/- 4 mm Hg, mean diastolic gradient was 3 +/- 2 mm Hg and pressure half-time was 83 +/- 17 ms, representing a calculated mean mitral valve area of 2.9 +/- 0.8 cm. Peak velocity in the left ventricular outflow tract was 0.9 +/- 0.2 m/s, indicating no obstruction to outflow. Our study confirms that mitral ring valvuloplasty produces a significant reduction in severity of MR, and this is achieved without obstructing left ventricular inflow or outflow.

Adult↗
PubMed1987

Effects of heart rate on ventricular size, stroke volume, and output in the normal human fetus: a prospective Doppler echocardiographic study.

The effect of heart rate on cardiac output in the fetal heart is controversial. We used Doppler echocardiography to investigate the effects of increasing heart rate on stroke volume and ventricular output in the normal human fetal heart. Heart rate was increased in 25 human fetuses (mean age 36 weeks) by auditory stimulation with a sound emitter placed on the mother's abdomen. Aortic or pulmonary diameters were measured at valve level from two-dimensional echocardiographic images and cross-sectional areas were calculated. Blood flow velocity spectra from the pulmonary artery or aorta were digitized to obtain flow velocity integrals before and after auditory stimulation. Stroke volume was calculated as the product of the flow velocity integral and the area of the great vessel. Prestimulation mean heart rate was 132 +/- 8 beats/min and increased after auditory stimulation to 158 +/- 9 beats/min (p less than .001). Stroke volume decreased with the increase in heart rate from 3.7 +/- 1.4 ml before stimulation to 3.0 +/- 1.1 ml after stimulation (p less than .001), but ventricular output calculated as the product of stroke volume and heart rate remained unchanged (0.48 +/- 0.18 liter/min before vs 0.48 +/- 0.17 liter/min after stimulation). The decrease in stroke volume was accompanied by a decrease in ventricular end-diastolic area, although there was no change either in end-systolic area or fractional change in area. This study demonstrates that increases in heart rate within the physiologic range in the normal human fetus result in a decrease in ventricular size and stroke volume but no change in ventricular output or ventricular shortening.

Cardiac Output↗
PubMed1987

Time course of resolution of pulmonary hypertension and right ventricular remodeling after orthotopic cardiac transplantation.

Most patients with severe congestive heart failure have secondary pulmonary hypertension (PHT). Elevation of pulmonary vascular resistance (PVR) to greater than 480 dynes.sec.cm-5 (6 Wood units) is currently the principle hemodynamic contraindication to orthotopic cardiac transplantation. We performed serial two-dimensional Doppler echocardiographic examinations and right heart catheterizations in 24 recipients (21 men, 14-58 years old) of orthotopic cardiac transplants to determine the time course of resolution of PHT and the concomitant remodeling of the donor right ventricle. Right and left heart filling pressures declined in parallel and reached the upper normal range at 2 weeks after the transplant procedure and remained unchanged at 1 year follow-up. Mean pulmonary arterial pressure (mm Hg) decreased from 38 +/- 9 preoperatively to 22 +/- 5 at 2 weeks and was 19 +/- 5 at 1 year after the transplantation procedure. At 1 year after surgery, PVR had decreased from 202 +/- 89 dynes.sec.cm-5 preoperatively to 99 +/- 36 dynes.sec.cm-5 (p less than .001), while cardiac output increased from 3.7 +/- 1.2 to 6.3 +/- 1.5 liters/min (p less than .001). Echocardiographic analysis showed that transplant recipients had an enlarged right ventricle on day 1 after surgery, and a volume overload contraction pattern and tricuspid regurgitation was present in the majority. This increase in right ventricular size was maintained at 1 year follow-up while the incidence of tricuspid regurgitation decreased. We conclude that there is rapid resolution of moderately elevated pulmonary arterial pressures after cardiac transplantation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1986

Intraoperative assessment of left ventricular heterogeneity.

To evaluate regional differences in thickness and systolic function of human myocardium perfused by angiographically normal coronary arteries in valvular and ischemic heart disease, we performed intraoperative epicardial M-mode mapping of ventriculographically normal wall regions (perfused by normal coronary arteries) in 22 subjects undergoing either coronary bypass surgery for stenoses in other vessels (n = 15) or mitral (n = 5) and/or aortic valve replacement (n = 4). In patients in whom both anterior and inferior walls were ventriculographically normal and normally perfused (n = 6), comparison of the two walls showed the anterior wall to be thicker at both end diastole and end systole, but there was no difference in the percentage of systolic thickening. Analysis of myocardium along the long axis revealed apical sites to be thinner than basal sites at both end diastole and end systole. Percentage of systolic thickening was also increased at apical sites. In patients in whom only the anterior wall was normal, a similar decrease in anterior wall thickness was noted at the apex. Thus systematic regional heterogeneity along both the left ventricular major and minor axes is found in the chronically diseased human heart as it is in the normal heart. Assessment of myocardial structure and function and of the effects of therapeutic interventions must take this heterogeneity into account.

Coronary Artery Bypass↗
PubMed1982

Ten-year experience of 359 epicardial pacemaker systems: complications and results.

In the last ten years (1970-1980) 457 patients underwent permanent pacemaker insertion in the Brompton Hospital. Our practice has been somewhat atypical in that the majority of these patients had epicardial leads, initially using a Cordis intramural sutured electrode (85 patients), and subsequently a Medtronic sutureless electrode (274 patients). Our initial experience with these electrodes was satisfactory, but more recently it has become apparent that the long-term morbidity and complication rate is high. The respective complication rates being 25% and 18% for sutured and sutureless epicardial electrodes. In this study, lead complications were defined as those requiring lead replacement, and problems most commonly encountered were high voltage threshold, infection, and lead fracture. Unless there are specific indications for epicardial pacing it is now our policy to treat patients requiring permanent pacing with endocardial systems. Our complication rate with this technique (90 patients) is significantly lower (9%).

Adolescent↗
PubMed1981

Prevalence of clinically unsuspected pheochromocytoma. Review of a 50-year autopsy series.

Pheochromocytoma is surgically curable, and lethal complications often ensue when the diagnosis is not made. We review 54 autopsy-proven cases of pheochromocytoma seen at the Mayo Clinic over the 50-year period 1928-1977. There were 31 females and 23 males, and the patients' ages ranged from 40 hours to 92 years (mean, 53 years). Pheochromocytoma was multiple in 10 patients (19%), extra-adrenal in 5 (9%), and malignant in 6 (11%). In 13 (24%) pheochromocytoma had been correctly diagnosed in life--after the investigation of hypertension in 8 patients, incidentally at laparotomy for unrelated conditions in 4 patients, and in association with the multiple endocrine neoplasia syndrome in 1 patient. In the group of 41 patients (76%) in whom pheochromocytoma had not been suspected clinically, hypertension also was a common finding (22 patients, 54%). Symptoms such as headache, sweating, and palpitations were nonspecific, but all occurred more often among the group of patients in whom the diagnosis had been made. For both groups, hypertensive or hypotensive or hypotensive crisis precipitated by surgery for unrelated conditions was a common cause of death. Prevention of such deaths requires a high degree of clinical alertness and biochemical screening tests for pheochromocytoma in patients with labile or accelerated hypertension.

Adolescent↗
PubMed1980

Left ventricular function in Friedreich's ataxia. An echocardiographic study.

Left ventricular function was assessed in seven patients with Friedreich's ataxia using computer-assisted analysis of the left ventricular echocardiograms and compared with those of 45 normal children matched for age and sex. The left ventricle in Friedreich's ataxia was symmetrically hypertrophied, cavity dimension was normal or small, and septal motion and peak velocity of circumferential shortening were normal in all patients. In diastole the duration of rapid filling was normal, peak rate of increase in left ventricular dimension was reduced in two patients, mitral valve opening was delayed with respect to minimum cavity dimension in seven, and there were significantly greater than normal increases in left ventricular dimension during the isovolumic period to mitral valve opening in seven, indicating abnormal and incoordinate relaxation. Peak rates of posterior wall systolic thickening and diastolic thinning were reduced in four and six patients, respectively, whereas peak rates of septal systolic thickening and diastolic thinning were reduced in one and four, respectively, suggesting a disproportionately greater impairment of the posterior wall than of septal function. The absence of asymmetric septal hypertrophy and mid-systolic closure of the aortic valve, the presence of normal septal motion, and the greater reduction in posterior wall than in septal dynamics are inconsistent with previous ideas that the heart disease of Friedreich's ataxia is identical to hypertrophic cardiomyopathy. Computer-assisted analysis of echocardiograms permits recognition of heart disease in Friedreich's ataxia before the onset of cardiac symptoms or development of clinical signs of heart disease.

Adolescent↗
PubMed1980

Haemodynamic effects of haematocrit reduction in patients with polycythaemia secondary to cyanotic congenital heart disease.

Acute reduction in haematocrit (without significant alteration of blood volume) in six patients with severe polycythaemia secondary to cyanotic congenital heart disease resulted in an increase in resting cardiac output without alteration in heart rate. Cardiac output was also increased during a constant-load exercise test after haematocrit reduction, and under these conditions total oxygen uptake was increased with consequent reduction in oxygen debt. These measurements confirm that the subjective improvement in such patients after haematocrit reduction is matched by physiological circulatory changes.

Adolescent↗