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Biomedical subjects

L T Mahoney

Publications and source records attributed to L T Mahoney.

At least 37 records · Page 2Linked to original sources
PubMed1991

Factors affecting tracking of coronary heart disease risk factors in children. The Muscatine Study.

The public health implications of reducing or preventing the excess increase in blood pressure and the acquisition of obesity during childhood years are important. Many children with high blood pressure, particularly those who are initially obese or become obese as young adults and those with excess left ventricular mass for body size, become adults with high blood pressure. Although blood pressure and cholesterol have been shown to track during childhood and from childhood into the adult years, the use of repeated determinations along with measures of obesity and information concerning family history of diabetes and coronary heart disease can significantly add to the prediction of future elevated levels.

Adolescent↗
PubMed1991

Childhood predictors of future blood pressure.

Blood pressure in infants and children is much lower than that in adults. It is suspected that children whose blood pressures are greatest for their age or body size may be destined for future hypertension. However, it is apparent that some children with lower blood pressures are also destined for hypertension as adults. Children with a family history of hypertension demonstrate greater blood pressure and heart rate responses to mental challenge. These responses are enhanced when a high salt diet is consumed. Increased maximal exercise systolic blood pressure and increased left ventricular wall mass in childhood add significantly to the prediction of future high blood pressure. In addition, the acquisition of excess weight for height from childhood to young adult life adds to the prediction of future blood pressure elevations. Both children and adults who are obese have significantly higher blood pressures than those who are lean. Approximately 34% of the variability in body mass index is explained by genotype differences at a single recessive locus, 41% by genotype differences at polygenic loci, and 25% by nongenetic factors. Thus, the genetic influence of obesity may be an important factor responsible for elevated blood pressure in both children and adults.

Adult↗
PubMed1989

Haemodynamic effects of rectal methohexitone for induction of anaesthesia in children.

Pulsed Doppler and two-dimensional echocardiography were used to determine the haemodynamic effects of rectal methohexitone in 12 children 32.4 +/- 3.8 months old and weighing 13.3 +/- 1.1 kg (mean +/- SEM). Heart rate, blood pressure and echocardiographic measurements of cardiac output, stroke volume and left ventricular end-diastolic and end-systolic volumes were obtained prior to the induction of anaesthesia. Anaesthesia was induced with 25 mg.kg-1 two per cent rectal methohexitone. Immediately following the onset of sleep all cardiovascular measurements were repeated. Following the induction of anaesthesia with rectal methohexitone there was a significant increase in heart rate. Blood pressure, cardiac index, stroke volume and ejection fraction were unchanged. It is concluded that rectal administration of two per cent methohexitone for the induction of anaesthesia in healthy paediatric patients has minimal haemodynamic effect.

Anesthesia, Rectal↗
PubMed1989

Haemodynamic effects of atropine during halothane or isoflurane anaesthesia in infants and small children.

In this study, two-dimensional and pulsed Doppler echocardiography were used to measure cardiovascular changes before and after IV atropine in 31 infants and small children during halothane (n = 15) or isoflurane (n = 16) anaesthesia. Prior to induction of anaesthesia heart rate (HR), mean blood pressure (MBP), and two-dimensional echocardiographic dimensions of the left ventricle and pulmonary artery blood flow velocity were measured by pulsed Doppler echocardiography. Cardiovascular measurements were repeated while anaesthesia was maintained at 1.5 MAC halothane (n = 15) or isoflurane (n = 16). Atropine 0.02 mg.kg-1 IV was then administered and two minutes later, a third set of cardiovascular data was obtained. Heart rate decreased during halothane anaesthesia but did not change significantly during isoflurane anaesthesia. Mean blood pressure, cardiac output (CO) and stroke volume (SV) decreased similarly during 1.5 MAC halothane or isoflurane anaesthesia. Ejection fraction (EF) decreased and left ventricular end-diastolic volume (LVEDV) increased significantly in both groups, but decreases in EF (32 +/- 5 per cent vs 18 +/- 5 per cent) and increases in LVEDV (18 +/- 7 per cent vs 7 +/- 5 per cent) were significantly greater during halothane than during isoflurane anaesthesia. Following atropine, HR increased more in the patients maintained with halothane (31 +/- 6 per cent), than during isoflurane anaesthesia (18 +/- 5 per cent). Atropine increased CO in both groups of patients, but SV and EF remained unchanged. When compared with awake values, HR increased similarly and significantly (18 +/- 4 per cent) following atropine in both groups, and CO returned to control levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1988

Coronary artery aneurysms due to Kawasaki disease: diagnosis with ultrafast CT.

Coronary artery aneurysms are the most serious complication of Kawasaki disease, and periodic screening examinations are necessary. Two-dimensional (2D) echocardiography represents the standard screening method; however, visualization of the distal coronary arteries is often limited. This report describes the complementary role of ultrafast computed tomography (CT) with 2D echocardiography in the evaluation of coronary artery aneurysms resulting from Kawasaki disease (mucocutaneous lymph node syndrome). Six pediatric patients with coronary aneurysms were examined with 2D echocardiography and ultrafast CT. Ten of 11 lesions were detected with ultrafast CT. The one missed coronary artery aneurysm was one of two contiguous aneurysms. Because of intersection thickness these two discrete aneurysms were interpreted as a solitary aneurysm. Ultrafast CT allowed detection of one aneurysm not initially visualized with echocardiography. In conclusion, ultrafast CT was found to be an effective complementary procedure with 2D echocardiography for noninvasively evaluating coronary artery aneurysms occurring as sequelae of Kawasaki disease.

Adolescent↗
PubMed1988

Left ventricular mass and exercise responses predict future blood pressure. The Muscatine Study.

Increased blood pressure and left ventricular mass are associated with increased morbidity and mortality in adults with coronary heart disease. To define the predictors of subsequent childhood blood pressure and left ventricular mass, serial echocardiograms and blood pressure responses during exercise were studied in 274 children aged 6 to 15 years, whose systolic blood pressures were in the high, middle, or low range. Persistence of rank order for left ventricular mass and blood pressure, at rest and during exercise, was maintained over a mean follow-up period of 3.4 years, with correlations ranging from 0.33 to 0.44. Subsequent systolic blood pressure was best predicted from initial resting and maximal exercise systolic blood pressures and left ventricular mass. Subsequent left ventricular mass was best predicted from initial left ventricular mass and maximal exercise diastolic blood pressure, but resting systolic blood pressure did not add to this latter prediction. Since left ventricular mass relates best to exercise blood pressure and not to resting blood pressure, left ventricular mass may provide an integrated view of the effects of blood pressure both at rest and during stress. We speculate that increased left ventricular mass in childhood may be an important predictor of subsequent hypertension and its consequences.

Adolescent↗
PubMed1987

Dominantly inherited dilated cardiomyopathy.

We describe a family in which there is segregating an autosomal dominant gene determining a cardiomyopathy. The pathodynamics is that of pump failure associated with dilatation of the heart, generally having an overt clinical onset from the fourth through seventh decades. Dysrhythmia is a frequent concomitant feature. There may be an associated skeletal myopathy, either producing a very mild proximal weakness or proving detectable only upon biopsy. This family is similar to other reported cases of familial dominant "idiopathic" dilated cardiomyopathy, but the nature of the heterogeneity within this category remains to be elucidated. The roles of echocardiography, cardiac biopsy, and skeletal muscle biopsy in the presymptomatic detection of the heterozygote are noted.

Adolescent↗
PubMed1987

Balloon dilation valvuloplasty of bioprosthetic valves in extracardiac conduits.

Six patients, aged 8 to 20 years, with valved right ventricle to pulmonary artery conduits were catheterized for balloon dilation valvuloplasty of stenotic and calcified bioprosthetic valves. Conduit stenosis was severe in all cases, with peak-to-peak systolic pressure gradients of 62 to 100 mm Hg (mean 79 mm Hg) and right ventricular systolic pressures of 87 to 115 mm Hg (mean 100 mm Hg). Three patients had good results, with residual peak-to-peak systolic pressure gradients of 20, 25, and 35 mm Hg. In two other patients, repeated balloon rupture before full inflation occurred, and residual gradients were high (55 and 60 mm Hg). One patient had substantial proximal and distal conduit obstruction in addition to valvular stenosis, and balloon dilation valvuloplasty was not attempted. No complications occurred in five patients; one patient required iliac vein exploration to remove an avulsed balloon fragment. Balloon dilation valvuloplasty can relieve bioprosthetic valve stenosis and postpone conduit replacement in some patients.

Adolescent↗
PubMed1987

Measurement of right ventricular volume using cine computed tomography.

Volume measurements of the right ventricle are clinically important, particularly in the assessment of congenital heart disease. The complex configuration of the right ventricular cavity, however, makes assessment of its volume difficult. Cine computed tomography (CT) permits depiction of cardiac anatomy in parallel, sequential, high-resolution tomographic images. To test whether cine CT would allow accurate, reproducible determination of right ventricular volumes, 11 excised, fixed canine hearts were scanned ex vivo. The endocardial contours of the right ventricular cavity were traced by two independent observers. The right ventricular cavity areas were measured in each image and right ventricular volume calculated by a Simpson's rule approximation. Actual right ventricular volume (range 24-86.5 mL) was measured by cavity fluid capacity. Right ventricular volumes derived from cine CT data correlated closely with actual volumes (R = .96, cine CT volume = 0.99 X [actual volume] + 0.2 mL). Interobserver correlation was excellent (R = .99). It is concluded that cine CT scanning permits accurate, reproducible determination of right ventricular volume ex vivo. This technique should be immediately applicable to the noninvasive evaluation of right ventricular function in children and adults.

Animals↗
PubMed1987

Enhanced forearm blood flow during mental stress in children of hypertensive parents.

This study compared changes in forearm blood flow, forearm vascular resistance, blood pressure, and heart rate elicited by mental stress (mental arithmetic) in 12 adolescents with a hypertensive parent and 13 age-matched adolescents with normotensive parents. The two groups did not differ in resting forearm blood flow, forearm vascular resistance, heart rate, or blood pressure. During mental stress, children with a family history of hypertension had a significantly greater increase in forearm blood flow than did children of normotensive parents (+37.5 +/- 8.0 vs +12.8 +/- 7.5%; p less than 0.05) and a trend toward reduced forearm vascular resistance (p = 0.08). Mental stress significantly increased systolic blood pressure (p less than 0.0001), diastolic blood pressure (p less than 0.001), and heart rate (p less than 0.03) in both groups. The blood pressure and heart rate responses to stress were not significantly different between groups. There was no evidence of a prolonged response or a different pattern of recovery in children with a family history of hypertension. This study indicates that regional blood flow responses underlying similar blood pressure increases during mental stress may be different in adolescents with and without a family history of hypertension.

Adolescent↗
PubMed1987

Surgical treatment of coarctation of the aorta after balloon angioplasty.

This study was designed to assess the long-term effects of balloon angioplasty for coarctation of the aorta. Eleven asymptomatic children, aged 4 to 6 years, underwent balloon angioplasty. Mean peak gradient fell from 50.5 +/- 4.7 mm Hg before angioplasty to 21.7 +/- 3.1 immediately after angioplasty. Children were then followed up at 3 to 6 month intervals and were recatherized 5 to 14 months after balloon angioplasty. On the basis of these catheterization findings, patients were divided into three groups: group I--four patients, residual gradient less than 10 mm Hg and no anatomic abnormalities; Group II--three patients, increase of gradient to greater than 25 mm Hg, mean 34 mm Hg; Group III--four patients, aneurysmal dilatation in the area of the balloon angioplasty. The seven patients in groups II and III underwent elective resection of their coarctation at 7 to 28 months after balloon angioplasty with end-to-end anastomosis. Somatosensory evoked potentials were monitored during the operation. There were no operative deaths and no gradients between arm and leg pressures postoperatively. One patient had mild paresis of the lower extremities. Pathologic examination of the specimens revealed an absence of muscle and elastic lamella in the area of the aneurysms. This finding was present in all specimens regardless of whether there was aneurysmal dilatation. Neofibroelastic proliferation at the site of the tear was responsible for persistent gradients. Balloon angioplasty may result in aneurysmal formation and/or recurrent stenosis in the area of the tear necessitating elective surgical repair. Surgical treatment is the same as for native coarctation when done early after balloon angioplasty, but may be associated with increased risk because of the lack of collateral circulation. Continued follow-up of these lesions is necessary.

Angioplasty, Balloon↗
PubMed1987

Pulsed Doppler and two-dimensional echocardiography: comparison of halothane and isoflurane on cardiac function in infants and small children.

The combination of two-dimensional and pulsed Doppler echocardiography was used to measure determinants of cardiac function in 20 ASA physical status I infants and small children (9 days-32 months of age) during equipotent halothane (n = 10) or isoflurane (n = 10) anesthesia in oxygen. Five sets of cardiovascular data were recorded in each patient. In the awake, unmedicated state prior to induction, at three different anesthetic levels, 0.75, 1.0, and 1.25 MAC (corrected for age) and a final measurement repeated at 1.25 MAC after the intravenous infusion of 15 ml X kg-1 of Lactated Ringers solution. The study was completed prior to intubation and surgery. Results are expressed as mean +/- SEM. Isoflurane and halothane decreased mean blood pressure from the awake level (isoflurane 76.6 +/- 2.3 to 60.6 +/- 3.1 mm, halothane 72.2 +/- 3.9 to 60.6 +/- 3.1 mm at 1.25 MAC). Isoflurane increased heart rate at all anesthetic levels (128.7 +/- 4.2 to 142.5 +/- 6.0 beats/min at 0.75 MAC). Halothane decreased heart rate at 1.25 MAC (124.6 +/- 4.6 to 119.4 +/- 3.5 beats/min). Isoflurane and halothane decreased cardiac index at 1.25 MAC. Stroke volume index decreased at 1.0 and 1.25 MAC with both isoflurane (36.9 +/- 3.8 to 30.2 +/- 3.5 ml/m2) and halothane (32.7 +/- 2.5 to 28.9 +/- 2.5 ml/m2). Ejection fractions also decreased significantly at 1.0 and 1.25 MAC in both groups of patients (22 +/- 6% at 1.25 MAC halothane and 28 +/- 8% at 1.25 MAC isoflurane).(ABSTRACT TRUNCATED AT 250 WORDS)

Age Factors↗
PubMed1986

Atrial septal defects that present in infancy.

The diagnosis of isolated secundum atrial septal defect (ASD) in infancy is uncommon. We studied 26 infants with ASD confirmed at cardiac catheterization. Of these, nine were born prematurely, 15 presented with symptoms of congestive heart failure, and only three were noted to have the clinical features of an ASD in spite of large left to right shunts. All but two patients responded to medical management. Spontaneous closure of the ASD was documented in 39% (ten) of the patients at ages ranging from 2 to 8 years. Twelve patients underwent surgical closure at a mean age of 4 years. No variables at presentation were predictive of subsequent spontaneous closure. In view of the high rate of spontaneous closure and the success of medical therapy, most infants with symptomatic ASD may be managed medically, allowing sufficient time to observe whether spontaneous closure will occur.

Blood Pressure↗
PubMed1986

Growth of the pulmonary arteries following Blalock-Taussig shunt.

The Blalock-Taussig (BT) shunt remains the standard systemic-to-pulmonary artery shunt. We reviewed our experience with the classic BT shunt in terms of mortality, patency, duration of palliation, and growth of the pulmonary artery. Records were reviewed in 49 consecutive patients, 25 of whom were less than one month old at the time of operation. They underwent a total of 53 BT shunts. Also, the pulmonary artery index (PAI), or the sum of the cross-sectional areas of the right and left pulmonary arteries standardized by the body surface area (BSA), was calculated. There were 4 operative deaths (7.5%) and 1 late death (2.0%). Early shunt thrombosis (within 72 hours postoperatively) occurred in 3 patients. Four patients required a second BT shunt, 5 underwent a palliative outflow tract reconstruction, and 5 required a polytetrafluoroethylene graft. Twenty-one patients underwent a corrective procedure, and 26 underwent a second cardiac catheterization. Of these 26 patients, 24 represent the subgroup used to assess the growth of the pulmonary arteries. The mean duration of palliation was 25.15 months. Mean PAI increased significantly from 127 +/- 40 mm2/BSA pre-shunt to 286.1 +/- 144 mm2/BSA post-shunt (p less than .004). This series demonstrates that the pulmonary arteries do grow after BT shunt. Pulmonary artery growth in patients with tetralogy of Fallot was greater than that in patients with single ventricle, and the duration of palliation was acceptable in most patients. Calculation of PAI may aid in the decision whether to perform a corrective surgical procedure or a second palliative shunt procedure.

Heart Defects, Congenital↗
PubMed1986

Tracking of blood pressure during childhood: the Muscatine Study.

Four thousand three hundred and thirteen children beginning at five to fourteen years of age have been examined on three to six occasions in Muscatine, Iowa on alternate years. To compare blood pressures throughout the period of observation each value was expressed as a percentile rank. For each subject the average percentile rank (level), the trend in rank and the variability over time were calculated. Values for height, weight, relative weight and triceps skinfold thickness measurements were expressed in the same fashion. The relationship between average rank of blood pressure and average rank of body size as well as between trend of blood pressure and trend of body size percentiles were significant (p less than .05). These observations indicate the importance of relative rate of growth in the establishment of the rank order of blood pressure.

Adolescent↗
PubMed1985

Pacemaker management for acute onset of heart block in childhood.

Four children aged 2 to 15 years are described who had Stokes-Adams syndrome as the primary cardiac manifestation of complete heart block. All had mild, nonspecific antecedent symptoms without signs of congestive heart failure. Viral neutralizing antibody titers (coxsackievirus B1 and B2) rose significantly in two patients. Electrocardiography demonstrated complete heart block associated with one or more of the following: right bundle branch block, left anterior hemiblock, left bundle branch block, intraventricular conduction delay, and ventricular standstill. In addition, second-degree heart block was seen during the initial or resolving phases of illness. To prevent further life-threatening episodes of Stokes-Adams syndrome, temporary transvenous pacemakers were placed. Two patients with persisting complete heart block required permanent pacemakers. At last examination, the remaining two patients had sinus rhythm and normal conduction. Nonsurgical acquired complete heart block is unusual in childhood, and may be the only manifestation of myocarditis. Extreme bradycardia, which causes syncope, requires immediate temporary cardiac pacing; if the bradycardia persists, a permanent pacemaker should be implanted.

Acute Disease↗