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Biomedical subjects

D W Kitzman

Publications and source records attributed to D W Kitzman.

At least 55 records · Page 3Linked to original sources
PubMed1997

Clinical factors associated with calcific aortic valve disease. Cardiovascular Health Study.

OBJECTIVES: The aim of this study was to determine the prevalence of aortic sclerosis and stenosis in the elderly and to identify clinical factors associated with degenerative aortic valve disease. BACKGROUND: Several lines of evidence suggest that degenerative aortic valve disease is not an inevitable consequence of aging and may be associated with specific clinical factors. METHODS: In 5,201 subjects > or = 65 years of age enrolled in the Cardiovascular Health Study, the relation between aortic sclerosis or stenosis identified on echocardiography and clinical risk factors for atherosclerosis was evaluated by using stepwise logistic regression analysis. RESULTS: Aortic valve sclerosis was present in 26% and aortic valve stenosis in 2% of the entire study cohort; in subjects > or = 75 years of age, sclerosis was present in 37% and stenosis in 2.6%. Independent clinical factors associated with degenerative aortic valve disease included age (twofold increased risk for each 10-year increase in age), male gender (twofold excess risk), present smoking (35% increase in risk) and a history of hypertension (20% increase in risk). Other significant factors included height and high lipoprotein(a) and low density lipoprotein cholesterol levels. CONCLUSIONS: Clinical factors associated with aortic sclerosis and stenosis can be identified and are similar to risk factors for atherosclerosis.

Aged↗
PubMed1997

Accuracy of transesophageal echocardiography in preoperative determination of aortic anulus size during valve replacement.

This prospective, blinded study evaluated the accuracy of transesophageal (TEE) and transthoracic echocardiography in predicting the size of the surgical aortic valve anulus in 20 consecutive patients undergoing aortic valve replacement. TEE was highly accurate in predicting surgical aortic valve anulus size (r = 0.98; p < 0.00001). The standard error of the TEE estimate of the size of the obturator anulus was only 0.04 mm, and in all cases the TEE estimate was within 1 mm of the direct surgical measurement. Both biplane and multiplane TEE probes were equally accurate and this accuracy was maintained over a wide range of sizes of surgical aortic anulus. Transthoracic echocardiography appeared less accurate in predicting anulus size (r = 0.64; p < 0.08). Therefore TEE can be used routinely for selection and preparation of aortic allografts before sternotomy, potentially reducing cardiopulmonary bypass pump time by 10 to 30 minutes and ensuring optimal size matching of the donor-recipient anulus.

Adolescent↗
PubMed1997

Morphology and dynamic change of discrete subaortic stenosis can be imaged and quantified with three-dimensional transesophageal echocardiography.

This report describes three-dimensional transesophageal echocardiographic findings in three consecutive patients with discrete subaortic stenosis. The discrete subaortic stenosis lesions included a circumferential, a remnant crescent, and a broken fibrotic subaortic membrane. The lesions were best imaged by using a three-dimensional transesophageal echocardiography-generated "aortotomy view" of the left ventricular outflow tract immediately below the plane of the aortic valve. The three-dimensional images correlated well with surgical and pathologic findings. The three-dimensional surface areas of the left ventricular outflow tract at the level of discrete subaortic stenosis during systole (0.8 +/- 0.5 cm2) and diastole (1.7 +/- 0.7 cm2) were measured by planimetry of the three-dimensional transesophageal echocardiographic images. The novel "aortotomy view" offered by three-dimensional transesophageal echocardiography provided direct visualization and quantification of discrete subaortic stenosis in a dynamic fashion. In summary, three-dimensional transesophageal echocardiography can accurately display and quantify discrete subaortic stenosis and could be a new clinically useful tool for assessing discrete subaortic stenosis and guiding surgical and transcatheter interventions.

Adult↗
PubMed1997

Treatment of hypotension after hyperbaric tetracaine spinal anesthesia. A randomized, double-blind, cross-over comparison of phenylephrine and epinephrine.

BACKGROUND: Despite many advantages, spinal anesthesia often is followed by undesirable decreases in blood pressure, for which the ideal treatment remains controversial. Because spinal anesthesia-induced sympathectomy and management with a pure alpha-adrenergic agonist can separately lead to bradycardia, the authors hypothesized that epinephrine, a mixed alpha- and beta-adrenergic agonist, would more effectively restore arterial blood pressure and cardiac output after spinal anesthesia than phenylephrine, a pure alpha-adrenergic agonist. METHODS: Using a prospective, double-blind, randomized, cross-over study design, 13 patients received sequential infusions of epinephrine and phenylephrine to manage hypotension after hyperbaric tetracaine (10 mg) spinal anesthesia. Blood pressure, heart rate, and stroke volume (measured by Doppler echocardiography using the transmitral time-velocity integral) were recorded at baseline, 5 min after injection of tetracaine, and before and after management of hypotension with epinephrine and phenylephrine. Cardiac output was calculated by multiplying stroke volume x heart rate. RESULTS: Five min after placement of a hyperbaric tetracaine spinal anesthesia, significant decrease in systolic (from 143 +/- 6 mmHg to 125 +/- 5 mmHg; P < 0.001), diastolic (from 81 +/- 3 to 71 +/- 3; P < 0.001), and mean (from 102 +/- 4 to 89 +/- 3; P < 0.001) arterial pressures occurred. Heart rate (75 +/- 4 beats/min to 76 +/- 4 beat/min; P = 0.9), stroke volume (115 +/- 17 to 113 +/- 13; P = 0.9), and cardiac output (8.0 +/- 1 l/m to 8.0 +/- 1l/m; P = 0.8) did not change significantly after spinal anesthesia. Phenylephrine was effective at restoring systolic blood pressure after spinal anesthesia (120 +/- 6 mmHg to 144 +/- 5 mmHg; P < 0.001) but was associated with a decrease in heart rate from 80 +/- 5 beats/min to 60 +/- 4 beats/min (P < 0.001) and in cardiac output from 8.6 +/- 0.7 l/m to 6.2 +/- 0.7 l/m (P < 0.003). Epinephrine was effective at restoring systolic blood pressure after spinal anesthesia (119 +/- 5 mmHg to 139 +/- 6 mmHg; P < 0.001) and was associated with an increase in stroke volume from 114 +/- 12 ml to 142 +/- 17 (P < 0.001) and cardiac output from 7.8 +/- 0.6 l/m to 10.8 +/- 1.1 l/m (P < 0.001). CONCLUSIONS: Epinephrine management of tetracaine spinal-induced hypotension increases heart rate and cardiac output and restores systolic arterial pressure but does not restore mean and diastolic blood pressure. Phenylephrine management of tetracaine spinal-induced hypotension decreases heart rate and cardiac output while restoring systolic, mean, and diastolic blood pressure.

Adrenergic Agonists↗
PubMed1996

Effects of pregnancy on the electrocardiogram in healthy subjects during strenuous exercise.

OBJECTIVE: Our purpose was to examine the nature and the frequency of electrocardiographic changes at rest and after bicycle exercise in early and late gestation compared with a group of nonpregnant subjects. STUDY DESIGN: Thirty-nine pregnant subjects had electrically braked bicycle exercise early and late in gestation. Eight nonpregnant subjects served as controls. Twelve-lead electrocardiograms were obtained during rest, exercise, and recovery. All electrocardiograms were analyzed by a cardiologist blinded to subject group and stage of the pregnancy. Data were analyzed by analysis of variance for repeated measures, and contingency tables were used to compare findings at rest and during exercise between the time periods. A p value < 0.05 was considered significant. RESULTS: T-wave inversion in V2 was more frequent in the pregnant than the nonpregnant subjects (p < 0.01). Subjects "late" in pregnancy had significantly fewer Q waves in II, III, and aVF than the nonpregnant group did. With exercise the time to onset of maximum ST depression was significantly shorter during pregnancy. CONCLUSION: Although minor electrocardiographic charges were found at rest and during exercise between the two groups, these should be considered normal unless associated with significant symptoms.

Adult↗
PubMed1995

Determination of left ventricular chamber stiffness from the time for deceleration of early left ventricular filling.

BACKGROUND: A noninvasive measure of left ventricular (LV) chamber stiffness (KLV) would be clinically useful. Our theoretical analysis predicts that KLV can be calculated from the time for deceleration of LV early filling (tdec) by [formula: see text] where p = density of blood, L = effective mitral length, and A = mitral area. METHODS AND RESULTS: We tested this hypothesis in eight conscious dogs instrumented for measurement of LV pressure (P) with use of a micromanometer and volume (V) with use of sonomicrometers. KLV was determined as the slope of the late diastolic portion of the LV P-V loop. KLV was varied from 0.99 +/- 0.35 to 2.58 +/- 0.92 mm Hg/mL with use of three graded doses of phenylephrine. We assumed that p = 1.0 and that L/A = 3.4. Thus, we predicted that KLV = (0.08/tdec)2. The LV filling pattern was determined from the derivative of LV volume (dV/dt). tdec was measured from peak early filling to the end of early filling. Predicted KLV and actual KLV were closely correlated (r = .94, SEE = 0.06 mm Hg/mL, P < .05). The regression line was close to the line of identity (slope = 0.95, intercept = 0.13 mm Hg/mL). Dobutamine did not alter the relation between tdec and KLV.tdec determined from the mitral valve flow velocity measured with Doppler echocardiography correlated well with that measured by dV/dt (r = .89, P < .01) but was 0.02 seconds longer. KLV-calculated tdec from the corrected Doppler tdec provided a good estimate of measured KLV (r = .75, SEE = 0.5 mm Hg/mL, P < .01). CONCLUSIONS: LV chamber stiffness can be determined from the time for deceleration of LV early filling, which can be measured noninvasively.

Animals↗
PubMed1993

Clinical utility of echocardiography in neurologic disorders.

Echocardiography is an established technology encompassing an increasingly wide variety of clinical situations including cardioembolism and the detection of CAD in patients with cerebral ischemia and in patients undergoing neurovascular surgery. Echocardiography will continue to occupy a pivotal role in clinical management and research in the area of brain heart interaction.

Brain↗
PubMed1991

Age-related alterations of Doppler left ventricular filling indexes in normal subjects are independent of left ventricular mass, heart rate, contractility and loading conditions.

The purpose of this study was to determine whether age-related alterations in Doppler diastolic filling indexes occur independent of cardiovascular disease and confounding physiologic variables. Ten old (62 to 73 years) and 10 young (21 to 32 years) healthy male volunteers were rigorously screened for cardiovascular disease and underwent comprehensive Doppler echocardiography, radionuclide ventriculography and invasive measurements of right heart and left atrial pressures. There were no differences between the two groups in the physiologic variables of left ventricular mass, volumes, ejection fraction, end-systolic wall stress, left atrial size, heart rate and right atrial, pulmonary artery, pulmonary capillary wedge and systemic arterial pressures. However, there were marked differences in Doppler left ventricular filling indexes. Compared with the young group, the old group had reduced peak early diastolic flow velocity (56 +/- 13 vs. 82 +/- 12 cm/s, p = 0.0002) and increased atrial diastolic flow velocity (59 +/- 14 vs. 43 +/- 10 cm/s, p = 0.009) and had a peak atrial/early flow velocity (A/E) ratio twice that of the young group (1.09 +/- 0.29 vs. 0.54 +/- 0.15, p less than 0.0001). Similar results were obtained for the time-velocity integrals of the peaks. Subjects in the old group also had a markedly reduced peak filling rate (274 +/- 62 vs. 448 +/- 152 ml/s, p = 0.004). In univariate and multivariate regression analyses, peak early and atrial flow velocities were not related to any of the physiologic variables measured once age was accounted for, although peak filling rate, a volumetric measure flow, was related to body surface area as well as age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Exercise intolerance in patients with heart failure and preserved left ventricular systolic function: failure of the Frank-Starling mechanism.

Invasive cardiopulmonary exercise testing was performed in 7 patients who presented with congestive heart failure, normal left ventricular ejection fraction and no significant coronary or valvular heart disease and in 10 age-matched normal subjects. Compared with the normal subjects, patients demonstrates severe exercise intolerance with a 48% reduction in peak oxygen consumption (11.6 +/- 4.0 versus 22.7 +/- 6.1 ml/kg per min; p less than 0.001), primarily due to a 41% reduction in peak cardiac index (4.2 +/- 1.4 versus 7.1 +/- 1.1 liters/min per m2; p less than 0.001). In patients compared with normal subjects, peak left ventricular stroke volume index (34 +/- 9 versus 46 +/- 7 ml/min per m2; p less than 0.01) and end-diastolic volume index (56 +/- 14 versus 68 +/- 12 ml/min per m2; p less than 0.08) were reduced, whereas peak ejection fraction and end-systolic volume index were not different. In patients, the change in end-diastolic volume index during exercise correlated strongly with the change in stroke volume index (r = 0.97; p less than 0.0001) and cardiac index (r = 0.80; p less than 0.03). Pulmonary wedge pressure was markedly increased at peak exercise in patients compared with normal subjects (25.7 +/- 9.1 versus 7.1 +/- 4.4 mm Hg; p less than 0.0001). Patients demonstrated a shift of the left ventricular end-diastolic pressure-volume relation upward and to the left at rest. Increases in left ventricular filling pressure during exercise were not accompanied by increases in end-diastolic volume, indicating a limitation to left ventricular filling.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Adrenal insufficiency from bilateral adrenal hemorrhage.

Bilateral adrenal hemorrhage is a rare cause of adrenal insufficiency in adults. Because of the nonspecific manifestations of adrenal insufficiency, antemortem diagnosis is difficult. Serial computed tomographic scans of the abdomen are a valuable adjunct in confirming the diagnosis of bilateral adrenal hemorrhage, which manifests as round or oval adrenal masses of high density that subsequently decrease in both size and density. The diagnosis should be suspected in any complex highly stressful illness, in the postoperative period, or in the presence of a coagulopathy in conjunction with hypotension, fever, or electrolyte disturbances. Herein we describe five patients in whom the computed tomographic scans suggested or confirmed the presence of bilateral adrenal hemorrhage. In three of the five patients, the presence of a circulating lupus anticoagulant was demonstrated. Once the diagnosis of adrenal hemorrhage is suspected, steroid replacement therapy should be initiated promptly.

Adrenal Gland Diseases↗
PubMed1990

Age-related changes in the anatomy of the normal human heart.

Recent information has expanded our knowledge regarding age-related changes in the normal heart. With advancing age there are significant increases in heart weight, ventricular septal and probably left ventricular free wall thickness, and in valve circumferences. In the myocardium, there are increases in fat, collagen, elastin, and lipofuscin. The geometry of the heart changes as well, due to decreasing base-to-apex dimension, rightward shift and dilatation of the aortic root, and left atrial dilatation. The aortic and mitral valves thicken and become fibrotic along their appositional surfaces, and their annuli are the sites of collagen degeneration, lipid accumulation, and calcification. The coronary arteries become tortuous, dilated, and focally calcified. There are atrophy and loss of specialized conduction tissue in the atria and ventricles. These changes, while usually modest, might diminish the ability of the aged heart to adapt to the stresses imposed by a number of cardiovascular diseases.

Adolescent↗
PubMed1989

Doppler left ventricular diastolic filling abnormalities in aortic stenosis and their relation to hemodynamic parameters.

Doppler mitral flow indexes and their relation to invasively measured hemodynamic diastolic indexes were assessed in 13 patients with isolated aortic stenosis (AS), and compared to Doppler indexes in 10 normal subjects matched for age, heart rate, left ventricular (LV) ejection fraction and LV load. Patients with AS showed no difference in Doppler early filling (E) indexes, but demonstrated greater Doppler atrial filling (A) indexes in comparison to normal subjects: atrial velocity (89 +/- 31 vs 56 +/- 7 cm/s), atrial integral (11.4 +/- 4.8 vs 5.7 +/- 1.6 cm), A/E velocity (1.69 +/- 0.89 vs 1.06 +/- 0.26) and A/E integral (3.53 +/- 6.64 vs 0.81 +/- 0.27) (all p less than 0.05). Doppler indexes in patients with AS did not correlate with hemodynamic indexes of LV relaxation or chamber stiffness. Significant correlations were observed between Doppler and angiographic peak filling rates (r = 0.70) and between Doppler atrial filling velocity and LV end-diastolic volume (r = -0.66), LV end-diastolic pressure (r = -0.48) and LV ejection fraction (r = 0.53) (all p less than 0.05). These data indicate that, compared to matched normal subjects, most patients with AS have an increased atrial contribution to LV filling. However, in patients with decreased LV function, atrial function may also be depressed, as indicated by a decreased atrial contribution to LV filling, resulting in "normalization" of the Doppler mitral flow pattern.

Aged↗
PubMed1989

Evaluation of a supervised exercise program in a geriatric population.

Most studies that assess the effects of exercise in the elderly involve subjects who are in good health. The objective of this prospective longitudinal study was to examine the impact of exercise on cardiovascular fitness, flexibility, and strength in an elderly population that included chronically ill individuals. Patients were recruited initially from a population of veterans over 64 years of age who use a VA outpatient clinic as their regular source of care. The exercise intervention consisted of 90 minutes of exercise 3 days per week at 70% of the patient's maximal capacity. Activities included stationary cycling, stretching, weight training, and walking. Of 69 patients who began the program, 49 (71%) reached 4-month follow-up. Most patients completing follow-up (76%) had at least one chronic disease, such as arthritis, hypertension, or heart disease. Patients who dropped out were more likely to have multiple chronic illnesses than those who remained in the program. Average weekly attendance was 65% and was stable over time. Improvements in cardiovascular fitness at 4-month follow-up were significant: Metabolic equivalents increased from 7.1 +/- 2.3 to 8.3 +/- 2.6 (P less than .001), treadmill time increased from 8.5 +/- 3.8 to 11.2 +/- 4.2 minutes (P less than .001), submaximal heart rate decreased from 123.7 +/- 18.8 to 118.8 +/- 19.4 beats per minute (P less than .001) and resting heart rate decreased from 68.1 +/- 10.6 to 63.3 +/- 11.6 beats per minute (P = .005).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1988

Age-related changes in normal human hearts during the first 10 decades of life. Part I (Growth): A quantitative anatomic study of 200 specimens from subjects from birth to 19 years old.

Heart weight, ventricular wall thicknesses, and valve circumferences were measured in 200 autopsy specimens of normal hearts from persons who ranged from birth to 19 years old. During this period of body growth, all cardiac measurements increased progressively and correlated with both age and body size (height, weight, and surface area). For most measurements, the mean predicted values were greater in male than in female subjects. Heart weight correlated better with body weight and body surface area than with body height or age of patients. In contrast, ventricular wall thicknesses and valve circumferences correlated better with age of the patients than with measurements of body size. In both sexes at all ages, the thickness of the left ventricle was greater than that of the right ventricle and was generally less than that of the ventricular septum. The circumference of the tricuspid valve usually exceeded that of the mitral valve, but aortic and pulmonary valve circumferences were similar. On the basis of these data, equations were derived and reference tables were constructed to predict normal values for heart weight, ventricular wall thicknesses, and valve circumferences.

Adolescent↗
PubMed1988

Age-related changes in normal human hearts during the first 10 decades of life. Part II (Maturity): A quantitative anatomic study of 765 specimens from subjects 20 to 99 years old.

Heart weights, ventricular wall thicknesses, and valve circumferences were measured in 765 autopsy specimens from normal hearts from persons 20 to 99 years old. Body weight was a better predictor of normal heart weight than was body surface area or height, and mean heart weights were greater in men than in women at all ages. When heart weights were indexed (divided by body surface area), the mean values per decade increased significantly in women between the 3rd and 10th decades of life (P less than 0.01) but remained relatively constant with time in men. We found no significant differences in ventricular wall thicknesses between men and women. Although indexed mean values for left and right ventricular wall thicknesses remained relatively constant in all decades, ventricular septal thickness increased significantly between the 3rd and 10th decades of life (P less than 0.001). Beyond the seventh decade of life, the mean ratio of septal to left ventricular free wall thicknesses exceeded 1.20, and the upper 95% confidence limit exceeded 1.50--an important consideration in evaluation of hypertrophic cardiomyopathy in elderly patients. Mean valve circumferences were usually greater in men than in women, but the opposite pertained when values were indexed by body surface area. In both sexes, all indexed mean valve circumferences increased progressively throughout adult life, although this trend was greater for semilunar than for atrioventricular valves. The mean circumference of the aortic valve surpassed that of the pulmonary valve in the 4th decade and approached that of the mitral valve by the 10th decade of life. Thus, in evaluation of annuloaortic ectasia, investigators should take into account the normal age-related changes in aortic valve dimensions.

Adult↗