Biomedical subjects
Publications and source records attributed to N E Hill.
The authors describe a method to account for patient-to-patient variability in electrocardiographic data. The method yielded criteria for healed inferior myocardial infarction with diagnostic performances better than those of traditional electrocardiographic parameters.
Path analysis was used to determine whether the effects of interparental conflict on children's depression and conduct disorder are mediated by 3 dimensions of parenting: acceptance, inconsistent discipline, and hostile control. The study extends the literature by testing this mediational model with a low-income, predominantly ethnic minority sample of preadolescent children and by examining the effects of multiple dimensions of interparental conflict from the child's perspective. Results supported the mediational model when analyses were based on child's reports of all variables but not when mother's reports were used to assess child depression and conduct problems. Exploratory analyses revealed unique mediational paths associated with conflict frequency and resolution, which were examined along with intensity as distinct dimensions of interparental conflict.
In 54 patients, we measured 3 different electrocardiogram (ECG) parameters required in the Symphony 1 trial and compared various combinations of pairs of measurements from 4 different sets of analog data and 1 set of digital data. Particularly for measurements of the durations of R waves in lead aVF, we found poor intraobserver and interobserver reliability and poor agreement between analog and digital data. There was much better agreement in measurements of the amplitudes of S waves in lead V3. The poorer agreement involving durations appears to be due to difficulties in accurately identifying the offsets of portions of the QRS complex, especially in lead AVF. We conclude that, particularly in measurements of duration, digital and analog data are not equivalent.
BACKGROUND: Orthostatic hypotension is a common phenomenon in the elderly. Hormonal changes during orthostatic stress have been described in elderly normotensive people and in those with essential hypertension. However, the hormonal response in elderly people who have systolic hypertension during orthostasis has not yet been quantified. METHODS: In this study we investigated 14 non-diabetic men, aged 60 to 75 years, with untreated systolic hypertension who were subjected to 45 degrees passive head-up incline on a tilt table for 15 min. Their hormonal profile and hemodynamic changes were analyzed before and after the stress. RESULTS: In the supine position, plasma levels of norepinephrine, atrial natriuretic peptide and aldosterone were in the normal range, while the plasma renin activity was low. Immediately upon tilt the systolic blood pressure fell but it reverted to baseline values after 15 min of orthostasis. At that time the cardiac output decreased while the systemic vascular resistance and the plasma norepinephrine concentration rose. The atrial natriuretic peptide appeared to fall, and the renin-aldosterone level did not change. CONCLUSION: The physiologic response to orthostatic stress in elderly people with systolic hypertension is comparable to that of elderly normotensive people and those with essential hypertension, i.e. a decrease in cardiac output and an increase in plasma norepinephrine levels. The atrial natriuretic peptide appeared to fall appropriately. The response of the renin-aldosterone system mimicked that in elderly patients with low renin essential isolated hypertension. These observations may have a bearing on the management of elderly people with systolic hypertension who also have orthostatic symptoms; they may not require a different approach from that needed for others of the same age group.
Research has provided some evidence of ethnic group, gender, and class differences in the socialization for achievement. However, there is little research on African American women with the exception of the studies of low-income, single mothers. To understand the similarities and differences in socialization for achievement based on social class, middle-class African American women from working- and middle-class backgrounds were studied using qualitative and quantitative methods to compare them on issues related to achievement socialization. Women from middle-class backgrounds reported that their parents had higher expectations for them and were more involved in their education than did women from working-class backgrounds. More middle-class parents expected their daughters to be successful in careers than did working-class parents. Women from working-class families did receive support from their parents but they did not have as much support as did the women from middle-class backgrounds. Women from working-class families perhaps made use of other sources to support their desire to succeed. There were no differences in perceived race-related socialization based on social class. Implications of these findings for future research are discussed.
The ratio of the 30th to the 15th cardiac cycle duration on an electrocardiogram (30:15 ratio) immediately after active standing from the supine position has been used as one of the markers of baroreflex function. A ratio of < or = 1.0 has been suggested to indicate baroreflex dysfunction. Blood pressure (BP) changes were measured and the 30:15 ratio was calculated after standing and during 45-degree passive head-up tilt from the supine position in 10 nondiabetic men (mean age +/- SE 70.1 +/- 1.05 years, and BP < 150/90 mm Hg). After tilt the decrease in systolic BP (from 132 +/- 4.8 to 117 +/- 6.3 mm Hg; p < 0.001) appeared to be larger than that after standing (from 132 +/- 4.6 to 123 +/- 5.8 mm Hg; p < 0.01), whereas the 30:15 ratios were 0.965 +/- 0.006 and 0.970 +/- 0.014, respectively, which suggested baroreflex dysfunction. Although the mean of the 2 ratios did not differ, the variance appeared to be less during tilting than after standing. Thus, the 45-degree passive head-up tilt appeared to be a better and more uniform inducer of orthostatic stress than active standing. Therefore, 45-degree head-up tilt was used in a group of 10 nondiabetic male patients (aged 70 +/- 1.46 years) with isolated systolic hypertension (systolic BP > 160 mm Hg, diastolic BP of < 90 mm Hg) to assess their baroreflex function. Upon tilting, their systolic BP decreased from 190 +/- 5.5 to 179 +/- 5.8 mm Hg (p < 0.05) and their 30:15 ratio was 0.985 +/- 0.011.(ABSTRACT TRUNCATED AT 250 WORDS)
The hemodynamic effects of orthostatic stress in elderly subjects with systolic hypertension were studied before and after long-term hydrochlorothiazide therapy (50 mg daily). Sixteen nondiabetic men aged 70 +/- 1 (SE) years participated in the study initially, and 12 completed 1 year of therapy. Patients underwent 45 degrees head-up incline on a tilt table before, after 1 month and after 1 year of therapy. Hemodynamic variables were measured in the following situations: (1) the supine position, (2) immediately after completion of passive 45 degrees head-up position at 0 minute, (3) at 15 minutes in the tilted state while patients performed intermittent foot movements to minimize gravitational pooling and simulate the standing position outside the laboratory, and (4) after returning to the supine position. Systolic and diastolic blood pressure (BP) decreased significantly after 1 month of therapy, and this reduction was maintained up to 1 year in all aforementioned body positions, with the exception of diastolic BP at 0 minute of tilt, which was significant at 1 year only. Before therapy was begun, there was a significant reduction in systolic BP immediately after completion of tilting; however, this was statistically insignificant both at 1 month and 1 year of therapy. Thus, the data may help dispel the concern of exacerbating the hypotensive response to orthostatic stress in patients with systolic hypertension after long-term thiazide diuretic therapy.
Patients with chest pain and normal coronary arteries (NCA) score higher on measures of neuroticism than patients with coronary artery disease (CAD). This relationship, coupled with findings linking mitral valve prolapse (MVP) and anxiety disorders, led us to examine prospectively the possibility that a greater incidence of MVP among NCA patients accounts for their elevated neuroticism scores. One-hundred-forty-four patients completed psychological tests and a structured interview prior to cardiac catheterization. Forty-one of the 144 patients (28%) had normal coronary arteries. Within the NCA group 29 percent had MVP; within the CAD group only 13 percent had MVP. Despite the significant difference between NCA and CAD groups on measures of neuroticism, there were no differences as a function of MVP status, nor was there an interaction of MVP and coronary arterial status. These findings support the case for an association between NCA and neuroticism independent of the presence or absence of MVP.
Explore the source record for details and available documents.
As many as 30% of patients with chest pain symptoms who are referred for arteriography are found to have normal coronary arteries. Research has shown that patients with anginal symptoms and normal coronary arteries score higher on neuroticism measurements (anxiety, depression and somatic concerns) at the time of catheterization than patients with anginal symptoms who have coronary artery disease. Research examining the cardiac course of chest pain patients with normal coronary arteries indicates that this is a nonprogressive disorder. Although follow-up studies of these patients report continued chest pain and diminished physical activity, these studies have ignored the psychologic status of the patients. Thus, it is not known whether their higher neuroticism scores at the time of catheterization persist following angiography or whether such elevated indexes of neuroticism are transient phenomena associated with precatheterization anticipatory stress. The present study examined 48 Veterans Administration Medical Center patients: 24 with anginal symptoms and normal coronary arteries and 24 with documented coronary artery disease. The patients completed a structured clinical interview and a set of psychologic inventories on the day before catheterization and 1 year later. The findings established continued high neuroticism scores among patients with anginal symptoms only and supported the findings of other investigators regarding continuing chest pain and restricted physical activity. The knowledge alone of benign coronary artery status resulted in virtually no change in the psychosocial status of these patients. Alternative treatment methods are discussed.
Traditional electrocardiographic (ECG) criteria for left atrial enlargement (LAE) emphasize the increased amplitude and width of the corresponding component of the hypertrophied atrium. Although a correlation exists between LAE and ECG criteria, a cause-and-effect relationship has not been conclusively demonstrated. Because the diastolic properties of the left ventricle directly influence left atrial emptying, these properties might also influence the ECG diagnosis of LAE. Therefore, the authors hypothesized that the ECG criteria for LAE are influenced by diastolic properties of the left ventricle as defined by Doppler-derived parameters.
The authors evaluated the ability of criteria involving abnormalities of repolarization to diagnose healed myocardial infarction (MI). They studied the Q, R, S, and T waves and the ST-segments of the electrocardiograms (ECGs) of 60 angiographic-normal patients, 63 patients with angiographic evidence of healed inferior MI, and 33 patients with angiographic evidence of anterior MI. The best individual criteria involving repolarization were T wave amplitude less than or equal to 0.4 mm in lead II for inferior MI (specificity, 93%: sensitivity, 67%) and T wave amplitude greater than 2.4 mm for anterior MI (specificity, 100%: sensitivity, 27%). These T wave criteria enhanced the diagnostic performances of otherwise marginal QRS criteria for both inferior and anterior MI. The authors conclude that ECG criteria that involve abnormalities of the T waves are useful for diagnosing healed MI.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Traditional electrocardiographic (ECG) and vectorcardiographic (VCG) criteria for left ventricular enlargement (LVE) understandably emphasize the increased tendency of the maximal electrical forces of ventricular depolarization to be directed toward the left. This tendency is manifested on the ECG by increased amplitudes of the R waves in leads I, AVL, V5 and V6 and by deeper S waves in lead V1. However, because the left ventricle is a relatively posterior as well as leftward structure in the thorax, LVE should also cause these forces to be directed posteriorly. Such changes in the anteroposterior dimension should be reflected in the VCG loop in the transverse plane and in the scalar ECG leads which are placed anterior to the heart. Therefore, we hypothesized that both the ECG and VCG criteria for LVE might be optimized if a variety of parameters that reflect alterations in the anteroposterior as well as in the right to left dimension are investigated.
Explore the source record for details and available documents.
Twenty-four men, mean age 63 +/- 1.7 years, with systemic systolic hypertension were studied before and after 1 month of therapy with oral hydrochlorothiazide, 50 mg/day. The control mean plasma volume was 2,664 +/- 96 ml, cardiac index 3.9 +/- 0.2 liters/min/m2, stroke volume index 52 +/- 2 ml/beat/m2, systemic vascular resistance 1,351 +/- 80 dynes s cm-5, plasma aldosterone 8.6 +/- 1.0 ng/dl and 24-hour urinary excretion of metanephrines 0.371 +/- 0.044 mg. On renin-sodium profiling in 23 patients, 12 were classified into a normal group and 11 into a low-renin group; none had high renin values. Based on multiple regression analysis, the 24-hour urinary excretion of total metanephrines appeared to be the single most important factor explaining 28% of the variability in systolic blood pressure (BP). After therapy with oral hydrochlorothiazide, the elevated systolic BP decreased (p less than 0.0001) and diastolic BP decreased (p less than 0.005), with concomitant reduction in systemic vascular resistance (p less than 0.03). Patients in both the normal- and low-renin groups had normal plasma volume and responded similarly to thiazide diuretic therapy, without symptomatic side effects.