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At least 937 records · Page 52Linked to original sources
PubMed2005

Direct comparison of magnetic resonance imaging and conductance microcatheter in the evaluation of left ventricular function in mice.

The aim of the present work was to study the reliability of conductance microcatheter volumetric measurements as compared to magnetic resonance imaging (MRI) in the same set of mice. Mice left ventricular (LV) volumes were monitored under basal conditions and in a hypertrophy model induced by transverse aortic constriction (TAC). Cardiac function was evaluated in isoflurane anesthetized mice (n = 8) by MRI followed by 1.4 F Millar microtip catheter measurements. The second group of mice with TAC-induced cardiac hypertrophy was studied eight weeks after surgery. Reliability of 3D-reconstructed MRI data was confirmed by comparison with autopsy masses (autopsy LV mass = 73.6 +/- 3.4 mg; MRI LV mass = 76.9 +/- 3.7 mg). Conduction catheter was found to greatly underestimate end-diastolic and end-systolic volumes and thus stroke volume as well as cardiac output in control mice (MRI: EDV = 79 +/- 8 microl, ESV = 27+/-9 microl, SV = 51 +/- 9 microl, CO = 25 +/- 6 ml/min; Catheter: EDV = 28 +/- 5 microl, ESV = 8 +/- 4 microl, SV = 19 +/- 4 microl, CO = 10 +/- 2 ml/min). However, values for ejection fraction showed no significant differences between the two methods. In the hypertrophy model, stroke volume and cardiac output were increased when measured with MRI (SV: +19 +/- 20%; CO: +28 +/- 27%), whereas catheter data showed opposite directional changes (SV: -22 +/- 37%; CO: -31 +/- 37%). Ejection fraction was found to be reduced only in catheter measurements (-31 +/- 26%). In summary, our data demonstrate that absolute volumetric values are strikingly underestimated by conduction catheter measurements and that even detection of directional changes with this method may not always be feasible.

Animals↗
PubMed2003

[Analysis of the criteria that contribute to the decision to harvest the heart in brain-dead organ donors].

OBJECTIVES: The number of cardiac transplantation procedures does not increase because of the lack of donor hearts despite an increase in the number of brain-dead organ donors. The criteria used to select a donor heart are not formally standardized. The aim of the present study was to analyze the criteria that contribute to the selection of a donor heart. TYPE OF STUDY: Descriptive, retrospective study. PATIENTS AND METHOD: Clinical parameters, the initial causes that lead to brain death, maximum doses of catecholamines, several biochemical markers of myocardial ischaemia/necrosis as well as several echocardiography criteria were extracted from a prospectively collected database. Univariate and multivariate (logistic regression) analyses were performed with the "harvested heart" as dependent variable and the above-cited independent variables. RESULTS: One hundred and eighty consecutive brain-dead patients admitted from 1st October 1998 to 31st December 2000 out of which 112 gave at least one organ were analyzed. Among these 112 patients, 59 (39 males and 20 females) were pre-selected as potential heart donors. Only 44 hearts were harvested. Logistic regression analysis showed that harvesting of the heart was more probable if the donor were a male, had no left ventricle systolic wall motion abnormalities, had low doses of norepinephrine and low serum troponin Ic concentrations. CONCLUSION: After an initial phase of selection, the final decision to harvest a heart is based on several criteria. These results should be an incentive to conceive a score that could allow a more formal decision process for heart harvesting.

Adolescent↗
PubMed2005

Regional and global right ventricular function in healthy individuals aged 20-90 years: a pulsed Doppler tissue imaging study: Umeå General Population Heart Study.

The aim of the present study was to describe regional and global right ventricular (RV) function in a wide age range of healthy subjects of both sexes. We studied 255 (125 females) healthy individuals randomly selected from the Umeå General Population Register, age 58 +/- 19 (range 22-89) years. RV function was studied using myocardial tissue Doppler imaging of the RV free wall. Isovolumic contraction (IVCv), systolic (Sv), early (Ev), and late (Av) diastolic velocities were measured. Furthermore, isovolumic periods and ejection time intervals were also measured. Conventional Doppler was used to study RV global filling properties. While systolic myocardial velocities were conserved over age, there was a decrease in myocardial E/A ratio with increasing age (r =-0.67, P < 0.001, for base) taken from the RV free wall. A similar age relation was found in RV global filling velocities with a reduced tricuspid E/A ratio (r =-0.57, P < 0.001). Furthermore, a significant correlation was found between global and regional E/A ratios at the basal (r = 0.58, P </= 0.001) and mid-segmental levels (r = 0.46, P </= 0.001). Systolic myocardial velocities behaved independent of age whereas regional as well as global E/A ratio were age-related. No relationship was found between regional isovolumic time intervals and age. Knowledge of these age-dependent relationships is fundamental when evaluating RV function in patients.

Adult↗
PubMed1986

Ventricular pacing improves exercise tolerance in patients with chronic heart block.

Exercise capacity was assessed by means of a simple six minute walking test in a group of 18 patients with heart block whose only presenting symptom was breathlessness. None was in overt cardiac failure. Patients were studied before and after implantation of a transvenous, ventricular, demand pacing system (study group). Eight patients with an implanted pacemaker admitted for elective generator replacement were assessed in the same manner (control group). Exercise capacity in the study group was significantly increased within 48 hours of pacing, and this improvement was maintained in most patients during the follow up period of up to 30 months. In contrast, exercise capacity was unaffected by generator replacement in the control group. Simple ventricular pacing produces symptomatic benefit in patients with heart block accompanied by breathlessness. This benefit is apparent within 48 hours of pacing and is maintained; it can be assessed objectively by a six minute walking test.

Aged↗
PubMed1975

[Modifications of contractility after left ventriculography. A new test in evaluation of myocardial function].

The action of the contrast material over the various contractility indices was assessed five minutes after left ventriculography. There was an increase of the contractility index in normal subjects. On the contrary, in coronary patients, the contractility function remained unchanged or was depressed, related to the presence or not, of signs of cardiac failure. Depression of the various indices was noted in subjects with primary cardiomyopathy. After recalling the mechanism of action of the contrast products on the cardiovascular haemodynamic parameters, the following practical conclusions were drawn in relation with a series of 65 cases of coronary heart disease: the late diastolic left ventricular pressure remained lower than 20 mmHg after ventriculography in the subjects with a normal ejection fraction; it incraeased between 20 and 30 mmHg in most of the subjects with an ejection fraction ranging from 0.4 and 0.6, finally it was constantly found above 35 mmHg in the subjects with severely disturbed ventricular contraction with an ejection fraction lower than 0.4. These results underline the interest of this simple test, easy to perform, consisting in measuring the left ventricular late diastolic pressure before and 5 minutes after left ventriculography.

Adult↗
PubMed2002

Improvement in exercise capacity in asymptomatic and mildly symptomatic adults after atrial septal defect percutaneous closure.

BACKGROUND: Controversy exists as to whether secundum atrial septal defects (ASDs) in asymptomatic or mildly symptomatic New York Heart Association (NYHA) class I or II adult patients should be closed. METHODS AND RESULTS: Thirty-seven patients (24 females; mean age 49.4 years, range 19 to 76) with a mean pulmonary to systemic flow ratio (Qp:Qs) of 2.1 (1.2 to 3.4) had a maximal oxygen uptake (VO2max) determination and echocardiographic measurement of right ventricular dimensions before and 6 months after elective percutaneous closure of ASD. At baseline, mean VO2max was 23.5+/-6.4 mL/kg per minute and was higher in the 15 NYHA I patients than in the 22 NYHA II patients (27+/-6.9 versus 20.8+/-4.6 mL/kg per minute; P=0.0015). VO2max increased significantly at 6 months (23.5+/-6.4 to 26.9+/-6.9 mL/kg per minute; P<0.0001). Improvement was as marked in NYHA I (+22%; P<0.0001) as in NYHA II patients (+12%; P<0.0001), in patients with Qp:Qs 1.2 to 2.0 (+16%; P<0.0001) as in those with Qp:Qs >2 (+12%; P<0.0001), and in patients > or =40 years of age (+14%; P<0.0001) as in those <40 years of age (+16%; P<0.0001). Compared with 15 of 37 patients before closure, 35 of 37 patients were in NYHA I at 6 months. Right ventricular dimensions decreased significantly (P<0.0001). CONCLUSIONS: Adult ASD patients significantly increase their functional capacity after percutaneous defect closure. This is observed even in patients classified as asymptomatic, in those with lesser shunts, and in older patients. These findings suggest that ASD closure in an adult population should be considered even in the absence of symptoms.

Adult↗
PubMed2001

[Deep breathing test type I diabetic patients and parameters of spectral analysis].

UNLABELLED: Nervous system injury, affecting also its autonomic part, occurs in the natural course of chronic complications in patients with type 1 and 2 diabetes. The aim of the study was to compare heart rate frequency analysis parameters at rest and after deep breathing test in healthy persons and in the group of type 1 diabetes patients without complications. The study was performed in 34 patients with type 1 diabetes without chronic complications (N0), hospitalized in the Chair and Department of Metabolic Diseases in 1993-1996. The control group (K) consisted of 23 healthy persons. All diabetic patients underwent examinations to identify chronic complications of the disease. Aiming at answering the question how simple physiological tests influence frequency parameters of heart rate variability, assessment of VLF, LF and HF parameters was performed at rest and after the deep breathing test. In both groups K and N0 no changes were observed in the spectrum power within VLF values after deep breathing compared to the initial values. In the group K the deep breathing test significantly (p < 0.001) increased spectrum power within LF values, whereas in the group N0 the test did not produce statistically significant changes of this parameter compared to the initial values. In the control group K as well as in diabetic patients N0 the test caused significant (p < 0.01 and p < 0.001, respectively) decrease in the HF spectrum power in comparison to the values at rest. VLF/LF ratio after the deep breathing test as well as LF/HF ratio at rest were significantly lower in the group K compared to the group N0. CONCLUSION: Analysis of the autonomic nervous system imbalance may be an indispensable tool in the early diagnostics of patients with type 1 diabetes. Results of spectrum analysis may be useful in cases when classical Ewing battery tests do not identify autonomic dysfunction.

Adult↗
PubMed1978

[Cardiorespirography in physiologic and pathologic premature infants].

The cardiorespirography investigation, carried out in 42 premature newborn has led to the following results: 1. The narrowed undulatory zone was stated more frequently in cases of prematurely born infants, than in those of mature ones.--2. A silent zone was a typical phenomen with pathological prematurely born infants. The silent zone of type b together with tachypnoe and apnoic attacks and decelerations, prevailed within the group of infants suffering from IRDS. A typical silent zone of type a together with bradycardia, bradypnoe and apnoic attacks without decelerations was found in infants with the symptoms of intracranial haemorrhage. There were observed the silent zone of type a and of type b in cases of severe neonatal infections. But apnoic attacks with decelerations proved to be more frequent than in cases suffering from IRDS and intracranial haemorrhage. The respiratory curves showed an accentuated respiratory periodicity.--3. Whereas in cases of infants with IRDS the correction of the acid base balance brought about the correction of CRG--a gradual passage from the silent zone of type b to the undulatory one, the correction of the acid base balance did not bring about any change in the type of the silent zone within the group of cases of infants suffering from intracranial haemorrhage.--4. The cardiorespirography would therefore be suitable to be used, in relation to acid base balance values, as an additional method of establishing differential diagnosis in neonatal pathological cases.

Acid-Base Equilibrium↗
PubMed1989

A non-invasive method for testing neural circulatory control in man.

Exaggerated cardiovascular responsiveness is common in young men and may cause non-specific symptoms and poor performance. Conventional autonomic function tests are not clinically useful. We have therefore designed a thermal entrainment method to evaluate sympathetic and parasympathetic cardiovascular function in subjects with dystonic symptoms and orthostatic intolerance. Oscillations of thermal gradient in the skin were produced by standardised periodic stimulation of the lower part of the arm with warm and cool water. Vasomotor activity of the skin induced oscillations of arterial blood pressure which were thought to be regulated by sympathetic and parasympathetic heart rate control and by oscillation of the sympathetically controlled peripheral vascular resistance. We tested the method in subjects with cardiovascular symptoms (n = 7) and controls (n = 7). At supine rest, the frequency response of the heart rate variability to the thermal stimulation at frequencies of 0.01, 0.02, 0.03 and 0.1 Hz was significantly different (p = 0.008) between symptomatic subjects and controls. The gain of the heart rate control was increased to 0.03 Hz [-1.3(SEM 0.5) dB v -3.8(0.8) dB, p = 0.068] and decreased at 0.1 Hz [-3.9(1.1) dB v -1.5(0.6) dB, p = 0.076] in the test group compared to the control group. At stimulus frequencies of less than 0.03 Hz the individual overall heart rate variability of the subjects with symptoms stayed below the mean control value, at 60(6) ms v 79(15) ms, p = 0.16. The cutaneous temperature oscillations at the site of stimulation, frequency response of the oscillations of the skin blood flow and respiration to the thermal stimulation, and mean heart rate were similar in the both groups. The results show that this thermal entrainment method quantifies the increased sympathetic and decreased parasympathetic cardiac control of subjects with dystonic symptoms.

Adult↗