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Biomedical subjects

H Dean

Publications and source records attributed to H Dean.

At least 19 recordsLinked to original sources
PubMed1992

Effects of the dipyridamole test on left ventricular function in coronary artery disease.

The dipyridamole stress test is used with thallium-201 to detect areas of inhomogeneity of blood flow that point to coronary artery disease (CAD). It is unclear whether dipyridamole produces inhomogeneous perfusion only or whether it actually decreases net flow in the obstructed vessels and produces true ischemia. It is also unclear what effect dipyridamole has on global and segmental left ventricular function. Therefore, ejection fraction, segmental wall motion and ventricular volume equivalents were measured before and after dipyridamole in 113 patients and 32 normal subjects. Ejection fraction responded in an abnormal fashion in 98 patients (87%), decreasing from 49 +/- 11% to 43 +/- 13% (p less than 0.0001), whereas it increased in 29 normal subjects (90%) from 57 +/- 6% to 64 +/- 10% (p less than 0.0001). Wall motion worsened distinctly in 75 patients (66%), and pressure/volume ratio deteriorated in 72%. The effect of dipyridamole lasted between 10 and 25 minutes, but was promptly reversed by aminophylline. These findings indicate that dipyridamole generally induces true ischemia in CAD. Furthermore, the degree of dysfunction is related to the angiographically assessed severity of CAD. The shortness of breath (seen in 10% of patients) may be partially explained by the findings, and it seems advisable to give aminophylline to every patient in order to promptly correct left ventricular dysfunction.

Adult↗
PubMed1988

Is ascites caused by impaired hepatic inactivation of blood borne endogenous opioid peptides?

Methionine enkephalin and catecholamines were measured in carefully collected plasma samples from 25 patients with cirrhosis and ascites, and 25 with cirrhosis without ascites, 15 disease and 15 healthy controls. Methionine enkephalin was invariably raised in the ascites group, the median value being 4.6-6.9 times that of the other three groups. Similarly, in the ascites group, median noradrenaline was increased 2.5-4.2 and median adrenaline 1.8-2.5 times that of the other groups. Plasma methionine enkephalin is considerably raised in patients with cirrhotic ascites and has actions which could enable it to be an initiating factor of ascites formation.

Ascites↗
PubMed1988

Increased intensity of the murmur of hypertrophic obstructive cardiomyopathy with carotid sinus pressure.

In a prospective study murmurs increased in intensity with carotid sinus pressure in 18 of 26 patients with hypertrophic obstructive cardiomyopathy (HOCM) (sensitivity, 69.2 percent for the 26 patients, 85.7 percent for the 21 patients in whom heart rate and blood pressure decreased with carotid sinus pressure). On the other hand, the murmur remained constant or decreased in all but one of 104 patients with valvular aortic stenosis, mitral insufficiency, hypertrophic nonobstructive cardiomyopathy, and systolic murmurs of miscellaneous origins (specificity, 99 percent; positive predictive value, 94.7 percent). Catheterization, indirect arterial pressure tracings, and echocardiographic studies indicated that carotid sinus pressure-induced bradycardia was associated with increased left ventricular outflow tract obstruction. The carotid sinus pressure-induced increase in the murmur is probably multifactorial: decreased aortic pressure and impedance; increased contractility immediately on sudden slowing of heart rate; further increase in obstruction as the mitral valve systolic anterior movement is enhanced; and delayed vasodilatation maintaining the obstruction even after return of heart rate to precarotid sinus pressure values. An increase in a systolic murmur with carotid sinus pressure is characteristic of HOCM.

Aortic Valve Stenosis↗
PubMed1987

Echocardiographic and hemodynamic correlates of diastolic closure of mitral valve and diastolic opening of aortic valve in severe aortic regurgitation.

Acute severe aortic regurgitation (AR) is characterized by a steep increase in left ventricular end-diastolic pressure, exceeding left atrial pressure and occasionally equilibrating with aortic diastolic pressure. These pressure phenomena correlate with the M-mode echocardiographic (echo) findings of diastolic closure of the mitral valve (DCMV) and diastolic opening of the aortic valve (DOAV). Six men, aged 23 to 48 years, with recent-onset, severe AR were evaluated by M-mode echo and pressures at cardiac catheterization. DCMV was seen in all 6 patients and DOAV in 4. Near-constant time intervals from the preceding R wave of the electrocardiogram to DCMV and DOAV were seen, even in 3 patients with varying RR intervals (1 with atrial fibrillation and 2 with asynchronous and demand atrial pacing). When the RR intervals were shorter than these intervals, DCMV and DOAV did not occur. Increasing the heart rate in the 2 patients by atrial pacing resulted in a marked decrease in left ventricular end-diastolic pressure. In conclusion, DCMV and DOAV have a near constant relation to the preceding R wave of the electrocardiogram, DCMV with competence of the mitral valve must be present for DOAV to occur, DOAV indicates that the diastolic blood pressure equals left ventricular end-diastolic pressure, and heart rate is an important factor influencing the hemodynamic and echocardiographic parameters in recent-onset, severe AR.

Adult↗
PubMed1986

Metabolic response to insulin induced hypoglycaemia in lean and obese subjects.

Metabolic response to insulin induced hypoglycaemia was examined in 8 lean and 11 obese subjects. The metabolic rate increased in lean and obese subjects during the hypoglycaemia. The mean response (as the sum of all the values above basal) was not significantly different between lean and obese subjects. The mean decrease in blood glucose and the mean hormonal response (increase in cortisol, adrenaline and noradrenaline) were not different between lean subjects and obese subjects. However, the metabolic response and noradrenaline response were variable in obese subjects and some obese subjects showed a poor response. These results suggest that in some obese subjects, there may be reduced thermogenic response to insulin induced hypoglycaemia.

Adult↗
PubMed1985

Maternal and cord blood glycated albumin and total serum proteins: correlation with maternal glycemic control and birth weight.

Maternal and cord blood glycated albumin and total protein levels were measured in three groups: normal women (nondiabetic women who gave birth to infants that were normal for gestational age), test women (women who had no evidence of glucose intolerance with screening procedures and who gave birth to large for gestational age infants), and women with gestational diabetes. In all cases the cord glycated albumin and total protein levels were 20% to 30% less than the corresponding maternal levels, and no correlation could be detected between cord and maternal blood concentrations. There was no significant difference in cord and maternal glycated albumin and total protein levels among the three groups, although there was a slight upward trend detected in the test and diabetic groups. There was no significant correlation between birth weight ratio and either cord or maternal values for any of the groups except the diabetic cord samples, where a significant negative correlation between glycated albumin and total protein and birth weight ratios was found. The implications of these findings are discussed in respect to the usefulness of cord and maternal glycated albumin and total protein in retrospective screening for gestational diabetes.

Adult↗
PubMed1985

Cord blood glycosylated (glycated) hemoglobin: correlation with maternal glycosylated (glycated) hemoglobin and birth weight.

Maternal and cord blood glycosylated hemoglobin levels were measured by an affinity chromatographic method in three groups: normal women (nondiabetic women who gave birth to infants that were normal for gestational age); test women (women who had no evidence of glucose intolerance with screening procedures and who gave birth to large-for-gestational age infants); and women with gestational diabetes. In all cases the level of cord blood glycosylated hemoglobin was approximately 40% less than the corresponding maternal blood levels, and no correlation could be detected between maternal and cord blood concentrations. The reference range for glycosylated hemoglobin in the normal maternal population was similar to that for nonpregnant adults. There was no significant difference in cord and maternal glycosylated hemoglobin levels among the three groups, although a slight upward trend was detected in the diabetic group. There was a lack of correlation of cord and maternal glycosylated hemoglobin with birth weight in all three groups. The implications of these findings are discussed in respect to the usefulness of cord and maternal glycosylated hemoglobin in retrospective screening for gestational diabetes.

Adult↗
PubMed1985

Unusual QRS morphology associated with transvenous pacemakers. The pseudo RBBB pattern.

Eleven patients with implanted pervenous pacemakers were found to have unusual QRS morphology resembling right bundle branch block (RBBB) on the 12-lead electrocardiogram. In nine patients, the tip of the electrode catheter was established with certainty to be in the right ventricular apex. In eight of the nine, the standard leads showed a left bundle branch block pattern (LBBB), whereas only the precordial leads V1 and V2 resembled RBBB. In only one of the nine was the RBBB pattern also seen in the standard leads. In all nine, recording the precordial leads one intercostal space below the usual space eliminated the RBBB pattern in V1-V2 and resulted in inscription of a QS complex, whereas recording the leads one space higher than usual enhanced the height of the R wave. This is explained by the marked superior and slight anterior orientation of the main QRS complex in right ventricular pacing. It is suggested that the pattern of RBBB in V1-V2 + LBBB in lead 1 be named pseudo RBBB pattern since it does not represent left prior to right ventricular activation.

Bundle-Branch Block↗
PubMed1985

Echocardiographic findings of mitral and tricuspid valve prolapse in primary pulmonary hypertension.

Echocardiographic findings in six patients with primary pulmonary hypertension are presented. Four of six patients had abnormal septal motion with prolapse of mitral and tricuspid valves. The other two had none of the three echocardiographic abnormalities. It is possible that hemodynamic changes in ventricular pressure gradients across the interventricular septum cause an abnormal septal motion and secondary AV valve prolapse.

Adolescent↗
PubMed1984

A new form of insulin resistance with growth retardation, fatty liver, and hypogonadotropic hypogonadism.

A 17-year-old boy presented with growth retardation, marked hepatomegaly, and sexual infantilism. Elevated fasting serum insulin levels and a blunted hypoglycemic response to exogenous insulin (up to 0.35 unit/kg) demonstrated severe insulin resistance. Neither anti-insulin nor anti-insulin receptor antibodies were present. The molecular size of his circulating insulin and its binding to IM-9 lymphocytes was normal. Despite high circulating insulin values, both erythrocytes and cultured skin fibroblasts showed normal insulin binding capacity and affinity. Tissue responsiveness was examined by measuring the insulin-induced increase in 2-deoxyglucose uptake into fibroblasts. Although the basal glucose transport rate was slightly lower than that of controls, the insulin-induced increase was normal. However, the normal increase in thymidine incorporation in response to insulin was blunted, as were the thymidine incorporation responses to epidermal growth factor and fibroblast growth factor. These studies demonstrate the possible existence of a new form of post-insulin receptor defect as a cause of insulin resistance, but underscore the difficulty that exists in defining the exact nature of the defect in these disorders.

Adolescent↗
PubMed1983

Serial two-dimensional echocardiography in infective endocarditis of the pulmonic valve.

Infective endocarditis was diagnosed in a 15-yr-old patient following closure of a patent ductus arteriosus several weeks previously. Pulmonic valve vegetations were detected by both M-mode and two-dimensional echocardiograms. The serial echocardiographic examinations revealed the emergence of a vegetation on the pulmonic valve, a marked decrease in its size subsequent to pulmonary embolism, reemergence of a vegetation upon relapse of the disease and its resolution 4 mo later. The echocardiographic findings and their correlation to the various stages of the disease are described.

Adolescent↗