PubMed Health⌕ Search

Biomedical subjects

K L Peterson

Publications and source records attributed to K L Peterson.

At least 19 recordsLinked to original sources
PubMed1992

Evaluation of inotropic effect of endothelin-1 in vivo.

The vasoconstrictive peptide endothelin-1 (ET-1) has been reported to exert a very important positive inotropic effect in vitro. To assess the effect of ET-1 on myocardial contractility in vivo, we compared the effect of intracoronary infusion of 10(-8) M ET-1 (constant coronary blood flow) to that of 10(-8) M dobutamine in 8 swine. ET infusion did not produce changes in segmental shortening (control vs. drug, mean +/- SD): 33.8 +/- 14.3 vs. 30.8 +/- 12.1%, shortening velocity: 10.3 +/- 4.3 vs. 10.7 +/- 4.5 mm/s, or maximum +dP/dt: 1,691 +/- 701 vs. 1,772 +/- 773 mm Hg/s, whereas dobutamine infusion induced an important increase in these measurements; segmental shortening: 36.9 +/- 14 vs. 48.4 +/- 18.8%, shortening velocity: 10.1 +/- 2.6 vs. 14.7 +/- 4.5 mm/s, and maximum +dP/dt: 2,041 +/- 567 vs. 2,389 +/- 765 mm Hg/s (all p less than 0.05). Mean myocardial blood flow assessed by microspheres was unchanged by ET-1 despite a marked increase in coronary artery pressure (88.6 +/- 12.9 vs. 157 +/- 8.8 mm Hg, p less than 0.001). Regional infusion of ET-1 at a dose provoking extensive coronary vasoconstriction does not induce any change in regional or global myocardial function in swine.

Adenosine↗
PubMed1992

Chronic major-vessel thromboembolic pulmonary artery obstruction: appearance at angiography.

The pulmonary angiograms of 250 patients evaluated for chronic thromboembolic pulmonary hypertension were reviewed. Pulmonary thromboendarterectomy was performed in each of these individuals, and the surgical findings were correlated with abnormal angiographic patterns. The pulmonary angiographic findings suggestive of chronic thromboembolic disease included "pouching" defects, webs or bands, intimal irregularities, abrupt vascular narrowing, and complete vascular obstruction. Pouching is reported by the authors to be a previously undescribed angiographic feature of this disease. Carefully obtained and properly interpreted pulmonary angiograms are necessary to confirm the diagnosis of operable chronic thromboembolic disease. Differential diagnostic possibilities should be considered prior to a decision to perform surgical correction.

Adolescent↗
PubMed1991

Catheter-based intravascular ultrasound imaging of chronic thromboembolic pulmonary disease.

Pulmonary thromboendarterectomy is now the treatment of choice for pulmonary hypertension due to chronic pulmonary thromboemboli. A precise assessment of location and extension of these thrombi is important because only proximal chronic pulmonary thromboemboli are accessible to surgery. Because intravascular ultrasound imaging can assess not only arterial luminal size, but also wall thickness, its value as a complement to angiography was assessed in 11 patients aged 35 to 64 years with severe pulmonary hypertension (systolic pulmonary artery pressure, mean +/- standard deviation 70 +/- 19 mm Hg; pulmonary artery resistance, 609 +/- 297 dynes.s.cm-5). Intravascular ultrasound was obtained in 10 of 11 patients and no complication occurred. Intravascular ultrasound identified 10 segments with suspected chronic pulmonary thromboemboli in 7 patients, all confirmed at operation. Nine segments were considered normal, all of which (except 1) were free of chronic pulmonary thromboemboli at operation. Image quality was highly dependent on pulmonary artery size and position of the catheter. Therefore, intravascular ultrasound of pulmonary arteries is feasible and safe in patients with pulmonary hypertension. It may help to assess the location and extension of the pathologic process involving pulmonary arteries.

Adult↗
PubMed1991

Right and left ventricular function after cardiac transplantation. Changes during and after rejection.

BACKGROUND: Attempts to identify noninvasive markers of ventricular dysfunction accompanying acute rejection have been hampered by a lack of detailed simultaneous hemodynamic data. Therefore, we prospectively performed serial monitoring of detailed left and right heart hemodynamic parameters in cardiac transplant recipients at the time of routine endomyocardial biopsy to better define the physiology of the allograft heart during and after acute rejection. METHODS AND RESULTS: To better assess the pathophysiology of the rejection process, 18 cardiac transplant patients were prospectively studied by serial right heart micromanometer catheterization and digital image processing at the time of routine endomyocardial biopsy. Eleven patients had 18 episodes of rejection. Studies of baseline (negative biopsy preceding rejection), rejection (acute moderate rejection), and resolved (first negative biopsy after rejection) states were compared. Seven patients who did not experience an episode of rejection served as the control group. Right ventricular minimum and end-diastolic pressures increased from baseline values of 0.9 +/- 3.2 and 6.9 +/- 3.7 mm Hg, respectively, to 3.2 +/- 5.5 and 9.9 +/- 6.6 mm Hg, respectively, with rejection (both variables, p less than 0.05) and remained elevated despite histological resolution of rejection (4.3 +/- 5.5 and 10.0 +/- 7.1 mm Hg, respectively; p less than 0.05 for both variables compared with baseline values). Concurrently, right ventricular end-diastolic volumes (133 +/- 29, 119 +/- 27, and 114 +/- 30 ml; baseline, rejection, and resolved, respectively) and left ventricular end-diastolic volumes (133 +/- 24, 117 +/- 20, and 113 +/- 30 ml; baseline, rejection, and resolved, respectively) significantly decreased during rejection and remained decreased after resolution of rejection (rejection and resolved compared with baseline values, p less than 0.05). Right ventricular chamber stiffness (0.055 +/- 0.035, 0.085 +/- 0.057, and 0.092 +/- 0.076 mm Hg/ml; baseline, rejection, and resolution, respectively; rejection and resolved compared with baseline values, p less than 0.05) increased with rejection and remained elevated after resolution of rejection. Right ventricular peak filling rate also increased from a baseline value of 2.48 +/- 0.45 to 2.76 +/- 0.63 ml end-diastolic volumes per second with rejection (p less than 0.05). Elevation of right ventricular filling pressures, peak filling rate, and chamber stiffness with a concomitant decrease in end-diastolic volume is consistent with a restrictive/constrictive physiology. Mean arterial blood pressure and systemic vascular resistance were elevated after the resolution of rejection (compared with either rejection or baseline values, p less than 0.05) associated with a higher mean daily dose of prednisone (resolved compared with either baseline or rejection values, p less than 0.05). The control group experienced a time-dependent increase in mean and diastolic systemic arterial pressures (both comparisons, p less than 0.05) without detectable diastolic dysfunction. CONCLUSIONS: Persistence of biventricular diastolic dysfunction may be due to an irreversible effect of rejection, although multifactorial changes in left ventricular afterload occur that may complicate serial assessment of ventricular function.

Adult↗
PubMed1991

Imaginary audience behavior in older adolescent females.

The purpose of this study was to explore the extent of imaginary audience behavior in older adolescent females to ascertain if such behavior continues beyond the years of early and middle adolescence. Subjects were 112 freshman females enrolled in a midwestern university during their first semester. Results indicated that college freshman displayed a greater degree of imaginary audience behavior than did younger adolescents when compared to scores reported by Elkind and Bowen (1979). Findings support the view that later adolescents' entry into new social environments results in greater protection of the self, a return to previous behaviors, and an increase in egocentrism as evidence in less willingness to reveal oneself to an audience.

Adaptation, Psychological↗
PubMed1990

A 62-dose, 6-month therapy for pulmonary and extrapulmonary tuberculosis. A twice-weekly, directly observed, and cost-effective regimen.

STUDY OBJECTIVE: To evaluate the efficacy and toxicity of a 62-dose, four-drug, 6-month, and directly observed regimen for treatment of pulmonary and extrapulmonary tuberculosis. DESIGN: An open, nonblinded clinical trial, with intended follow-up of patients for 36 months after the completion of therapy. SETTING: A metropolitan tuberculosis clinic in a public health department. PATIENTS: From March 1981 through April 1989, we enrolled 160 patients with suspected or known tuberculosis; 35 of these patients were excluded from the analysis. INTERVENTIONS: Isoniazid, rifampin, pyrazinamide, and streptomycin were administered daily for 2 weeks; these drugs were then given in higher doses twice weekly for 6 weeks, followed by isoniazid and rifampin twice weekly for 6 weeks, followed by isoniazid and rifampin twice weekly for 18 weeks. A total of 62 doses were administered, and all therapy was directly observed by a nurse or an outreach worker. MEASUREMENTS AND MAIN RESULTS: Of the 125 evaluable patients, 101 (81%) had pulmonary tuberculosis, 7 (6%) had both pulmonary and extrapulmonary involvement, and 17 (13%) had extrapulmonary disease only. Seventy-one (57%) patients had a history of recent alcoholism. There were two relapses (1.6% +/- 2.2%), occurring 6 and 56 months after the completion of therapy. The time at which sputum samples became culture negative in pulmonary patients ranged from 1 to 19 weeks (median, 4.6 weeks); 40% +/- 9.6% of patients were culture-negative after 4 weeks of therapy, 75% +/- 8.5% after 8 weeks, 94% +/- 4.7% after 12 weeks, 97% +/- 3.3% after 16 weeks, and 100% after 20 weeks. Adverse drug reactions included hyperuricemia (greater than 178 mumol/L [3 mg/dL] above normal) secondary to pyrazinamide in 80 patients (64%), twofold or greater elevations of aspartate aminotransferase in 21 patients (17%), 1.5-fold or greater elevations of alkaline phosphatase in 33 patients (27%), cutaneous abnormalities in 8 patients (6%), nausea in five patients (4%), and dizziness in 1 patient (1%). CONCLUSIONS: This 62-dose, largely twice-weekly tuberculosis treatment regimen is efficacious and relatively nontoxic and is especially useful for patients in whom directly observed therapy is indicated.

Adolescent↗
PubMed1990

Intracoronary urokinase for intracoronary thrombus accumulation complicating percutaneous transluminal coronary angioplasty in acute ischemic syndromes.

Intracoronary urokinase was used to treat flow-limiting intracoronary thrombus accumulation that complicated successful percutaneous transluminal coronary angioplasty (PTCA) during acute ischemic syndromes in 48 patients who were followed up through the acute phase of their illness. The study group comprised 10 patients with unstable angina pectoris, 18 patients with an evolving acute myocardial infarction, and 20 patients with postinfarction angina. The initial mean percent coronary diameter stenosis for the entire population was 95 +/- 7% and decreased with initial PTCA to 41 +/- 20% (p less than 0.001), with improved corresponding coronary flow by Thrombolysis in Myocardial Infarction trial (TIMI) grade. However, thrombus accumulation then resulted in a significant increase in percent diameter stenosis to 83 +/- 17% (p less than 0.001); a corresponding significant reduction in coronary flow also occurred by TIMI grade. After administration of intracoronary urokinase (mean dose, 141,000 units; range, 100,000-250,000 units during an average period of 34 minutes), with additional PTCA, mean percent diameter stenosis significantly decreased to 34 +/- 17% (p less than 0.001); a correspondingly significant improvement in mean coronary flow by TIMI grade occurred to 2.9 +/- 0.2. Overall, the angiographic success rate was 90%. There were no ischemic events requiring repeat PTCA and no procedure-related myocardial infarctions or deaths before hospital discharge. One patient was referred for urgent coronary artery bypass graft surgery after a successful PTCA. Plasma fibrinogen levels were obtained in 15 patients, and in no patient was the level below normal for our laboratory.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Familial aortic dissecting aneurysm.

A family is described in which nine members over two generations had an aortic dissecting aneurysm or aortic or arterial dilation at a young age. The family has been followed up since 1977 after the death of a second teenager from a kindred of 11. None of the patients had the Marfan syndrome or a history of systemic hypertension. Three members died of ruptured aortic dissecting aneurysm and acute hemopericardium at 14, 18 and 24 years of age, respectively; a fourth member died suddenly at age 48 years, a few years after aortic repair for aneurysmal dilation. One member underwent surgical repair of an ascending aortic dissecting aneurysm at age 18 years and is still alive. Four members are currently under close medical observation for aortic or arterial dilation. Histologic examination of the aortic wall at autopsy or surgery in three patients revealed a loss of elastic fibers, deposition of mucopolysaccharide-like material in the media and cystic medial changes. Types I and III collagen from cultured fibroblasts appeared normal on gel electrophoresis. Results of indirect immunofluorescent studies of the elastin-associated microfibrillar fiber array in skin and fibroblast culture from multiple family members were also normal. This dramatic familial cluster of aortic dissecting aneurysm and aortic or arterial dilation suggests a genetically determined disease of autosomal dominant inheritance although the basic defect remains unknown.

Adolescent↗
PubMed1989

Age-appropriate behaviors: a comparison of three generations of females.

The purpose of this study was to examine differences in older adolescent and adult females' perceptions of age-appropriate behavior in adults. Subjects were three generations of maternally related females (95 older adolescents, 78 mothers, 83 grandmothers) who were administered a questionnaire designed to assess age-appropriate behaviors in three broad categories: recreation, occupation/career, and family. Major findings were that older adolescents were most tolerant of behaviors performed by individuals at varying ages while older women most closely ascribed to age constraints, and that the greatest agreement on appropriateness of age constraints concerned family relationships while least agreement concerned recreational activities. Results support the view that adolescents' values on family issues are consistent with those of their parents, and suggest that adherence to age norms increases throughout the life span or are the result of generational differences in socialization.

Adult↗
PubMed1988

Densitometric regional ejection fraction: a new three-dimensional index of regional left ventricular function--comparison with geometric methods.

Densitometric regional ejection fraction obtained by computer analysis of digital subtraction ventriculography was evaluated as a new, quantitative, three-dimensional index of regional left ventricular performance. Eighteen patients with coronary artery disease and seven control subjects had right anterior oblique ventriculography at rest and immediately after rapid atrial pacing using central venous injection of contrast material. Regional left ventricular ejection fraction was determined by densitometry in six segments drawn around the end-diastolic center of gravity, and compared with two conventional indexes of segmental wall motion: area and radial regional ejection fraction. Densitometric, area or radial regional ejection fraction was classified as abnormal if it fell at least 2 standard deviations below the corresponding mean value in the normal group. The densitometric method did not require outlining of the end-systolic left ventricular silhouette and was the easiest and fastest to perform of all three techniques. In addition, intra- and interobserver reproducibilities were higher with the densitometric method (r = 0.97 and 0.95) than with either the area (r = 0.84 and 0.82) or the radial method (r = 0.82 and 0.76). Regional left ventricular dysfunction as assessed by the densitometric, area and radial techniques allowed the detection of coronary artery disease in 50, 50 and 44% of the patients at rest and in 83, 67 and 61% of the patients in the post-pacing period, respectively. Post-pacing regional left ventricular dysfunction accurately predicted the presence or absence of greater than 70% diameter stenosis in the supplying coronary artery in 75, 67 and 56% of the cases, respectively. Thus, densitometric analysis of digital subtraction ventriculography allows a fast and reproducible three-dimensional determination of regional left ventricular ejection fraction. Using this technique, pacing-induced regional dysfunction can be detected in most patients with coronary artery disease and corresponds well with the location of significant coronary artery lesions.

Absorptiometry, Photon↗
PubMed1988

Early changes of right heart geometry after pulmonary thromboendarterectomy.

To determine the changes in right heart hemodynamics and geometry early after surgery for chronic pulmonary hypertension due to large vessel thromboembolic occlusion, 30 patients were evaluated 8 +/- 8 days (mean +/- SD) before and 6 +/- 4 days after pulmonary thromboendarterectomy by two-dimensional echocardiography and right heart catheterization. Surgery resulted in an early significant improvement in hemodynamic variables including mean pulmonary artery pressure (48 +/- 12 to 28 +/- 8 mm Hg, p less than 0.001), right ventricular systolic pressure (76 +/- 20 to 47 +/- 15 mm Hg, p less than 0.001), pulmonary vascular resistance (935 +/- 620 to 278 +/- 252 dynes.s.cm-5, p less than 0.001) and cardiac index (2.0 +/- 0.5 to 2.9 +/- 0.6 liters/min per m2, p less than 0.001). Similarly, echocardiographic variables of right heart structures, which were well outside the normal range preoperatively, improved significantly early after thromboendarterectomy. These included diameters of the pulmonary artery (2.8 +/- 0.3 to 2.4 +/- 0.4 cm, p less than 0.001), inferior vena cava (2.9 +/- 0.6 to 2.2 +/- 0.4 cm, p less than 0.001) and right atrium (6.8 +/- 1.5 to 5.9 +/- 1.5 cm, p less than 0.001) as well as right ventricular short axis (4.5 +/- 0.8 to 3.7 +/- 0.8 cm, p less than 0.001) and long axis (8.7 +/- 0.9 to 8.1 +/- 0.9 cm, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Quantitative assessment of regional left ventricular function by densitometric analysis of digital-subtraction ventriculograms: correlation with myocardial systolic shortening in dogs.

Conventional wall motion analysis of contrast ventriculograms assesses only that part of the wall that is tangential to the x-ray beam. To assess regional left ventricular function in three dimensions, a new computerized method based on densitometric analysis of digital subtraction left ventriculograms was developed and validated in nine open-chest dogs instrumented with a circumflex coronary artery occluder and sonomicrometers in the anterior and posterior walls. Each dog underwent digital subtraction ventriculography at baseline and at five levels (I to V) of dysfunction of the inferior wall induced by progressive stenoses of the circumflex coronary artery. The ventriculogram was divided into six segments around the end-diastolic center of gravity. Time-volume curves were obtained by densitometry in the normal anterior and ischemic inferior segments containing the sonomicrometers. From these curves, regional ejection fraction (R-EF), regional peak ejection rate (R-PER), and regional phase (R-PH) and amplitude (R-AMP) of the first Fourier harmonic were derived. From baseline to level V of dysfunction, myocardial systolic shortening determined by sonomicrometry decreased by 124 +/- 34% of control (mean +/- SD; p less than .001) in the ischemic wall, while it increased by 12 +/- 19% (NS) in the normal wall. At the same time, R-EF, R-PER, and R-AMP decreased in the ischemic segment by 65 +/- 12%, 46 +/- 30%, and 45 +/- 15% of control, respectively (all p less than .01), while they remained unchanged or increased in the normal segment. R-PH was delayed by 14 +/- 5% (p less than .01) in the ischemic segment, but remained unchanged in the normal segment, reflecting the asynchrony of regional left ventricular contraction during ischemia. Densitometric indexes of regional function correlated well with sonomicrometric systolic shortening both in normal and ischemic segments, with r values of .84 for R-EF, .80 for R-AMP, .64 for R-PER, and .55 for R-PH (all p less than .0001). Thus, densitometric analysis of digital subtraction left ventriculograms allows three-dimensional assessment of the extent, velocity, and synchrony of regional left ventricular contraction. Densitometric indexes of regional contraction correlate well with direct measurements of myocardial systolic shortening and are useful in quantitating regional left ventricular dysfunction.

Animals↗
PubMed1988

Early diastolic filling dynamics during experimental mitral regurgitation in the conscious dog.

Diastolic flow into the left ventricle during mitral regurgitation must increase as total stroke volume increases in response to the volume overload. The mechanisms that allow augmented diastolic filling are not fully defined. Accordingly, the left ventricle of five dogs was instrumented with a micromanometer and sonomicrometers and studied during the conscious state before (control) and after the creation of significant mitral regurgitation. Serial measurements were made at control and up to 4 weeks after the creation of the volume overload. Heart rate, peak systolic wall stress, and peak positive dP/dt showed no significant changes between control and subsequent observations. End-diastolic volume and total stroke volume progressively and significantly increased during the 4-week course. When compared with the control state (51 +/- 4, mean +/- SD), the filling fraction during the first 40% of diastolic time was increased at 4 days (67 +/- 10%, p less than 0.001), 2 weeks (72 +/- 6%, p less than 0.001), and 4 weeks (76 +/- 10%, p less than 0.001). During the period of adaptation to the volume overload, filling fraction correlated with end-diastolic volume (r = 0.52, p less than 0.02) and total stroke volume (r = 0.80, p less than 0.001). Compared with the control state (0.81 +/- 0.04), eccentricity of the left ventricle at end systole decreased at 4 weeks (0.79 +/- 0.06, p less than 0.05); the absolute change in this ratio during the first 40% of diastolic time was significantly augmented at 2 weeks (0.09 +/- 0.02, p less than 0.05) and 4 weeks (0.11 +/- 0.04, p less than 0.005) compared with control (0.05 +/- 0.02). Ventricular elastance (pressure/volume) at end systole (minimum volume) was 1.70 +/- 0.50 mm Hg/ml at control, 1.09 +/- 0.46 at 4 days (p less than 0.05), 0.96 +/- 0.42 at 2 weeks (p less than 0.01), and 0.99 +/- 0.22 at 4 weeks (p less than 0.01). Moreover, the elastance change during the rapid-filling phase was significantly diminished after creation of mitral regurgitation. Thus, during the volume overload of mitral regurgitation, the left ventricle accommodates a higher percentage of its total stroke volume during early diastole; this adaptation can be correlated with augmented systolic shortening, and thereby with increased restorative forces or elastic recoil, and with reduced chamber elastance and eccentricity during the early part of diastole. Other potential mechanisms include altered systolic and relaxation loading, augmented elastic recoil of the left atrium, left atrium and left ventricular pressure gradient, accelerated myocardial inactivation, and increased adrenergic stimulation.

Animals↗
PubMed1988

Temporal Fourier transform of digital angiograms for left ventricular regional wall motion analysis.

To determine whether or not the first harmonic of a temporal Fourier transform, applied pixel-by-pixel on time-intensity curves, can detect the subtle wall motion abnormalities due to ischemia, 6 dogs were instrumented with a micromanometer in the left ventricles, a hydraulic cuff occluder around the circumflex coronary artery, and sonomicrometers on the inferior (ischemic) and anterior (non-ischemic) walls. Left ventricular images, obtained after contrast injection via the pulmonary artery, were compared with dimension signals in control and 3 progressive levels of coronary stenosis (Stenosis I, II and III). Normalized, digital functional images (512 x 512 matrix, 256 shades of gray/pixel) were divided into anterior, apical, and inferior areas to acquire regional mean phase (degrees) and amplitude (intensity units) values. After inducing stenosis, phase in ischemic region significantly increased at all 3 levels of stenosis, whereas amplitude significantly decreased at Stenosis II and III. However, amplitude images showed clearly the topographic site of ischemia. There was a progressive increase in phase and decrease in amplitude in ischemic areas as the percent wall thickening (%WTh) fell (phase vs. %WTh: r = -0.55, p less than 0.005; amplitude vs. %WTh: r = 0.71, p less than 0.001). Heart rate and peak systolic pressure showed no significant changes during stenosis. We conclude that quantitative functional images, generated from a temporal Fourier transform, are sensitive to the detection of left ventricular regional wall motion abnormalities during mild, moderate, and severe degrees of ischemia.

Animals↗
PubMed1987

Ischemic myocardial dysfunction assessed by temporal Fourier transform of regional myocardial wall thickening.

A Fourier analysis including the first 20 harmonics was performed on sonomicrometric measurements of regional myocardial wall thickness in eight conscious dogs under control conditions and at four levels of ischemia produced by a hydraulic occluder on the left circumflex coronary artery. Systolic wall thickening was reduced from 26.47 +/- 6.20% (S.D.) (control) to 22.05 +/- 5.73% (mild stenosis), 17.00 +/- 5.86% (moderate stenosis), 11.46 +/- 3.56% (severe stenosis), and 3.69 +/- 2.57% (30-second occlusion), values significantly different from each other (p less than 0.01). The amplitude of the first harmonic decreased stepwise from 1.35 +/- 0.31 to 1.08 +/- 0.29 mm, 0.90 +/- 0.27 mm, 0.69 +/- 0.24 mm, and 0.43 +/- 0.12 mm, all significantly different from each other (p less than 0.05). These amplitude values correlated to percent systolic wall thickening (r = 0.894, p = 0.001). A phase shift of the first harmonic from 137 +/- 11 to 139 +/- 14 degrees, 150 +/- 15 degrees (p less than 0.05 vs control), 161 +/- 21 degrees (p less than 0.01 vs control), and 191 +/- 21 degrees (p less than 0.01 vs control and severe stenosis) correlated with the increase in time from end diastole to the point of maximum wall excursion (r = 0.662, p less than 0.001). These data indicate that the extent of ischemic regional myocardial hypokinesis can be adequately described by the amplitude of the first harmonic, and that the asynchrony of ventricular contraction and relaxation can be detected from the phase of the first harmonic.

Animals↗