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PubMed1996

Dobutamine positron emission tomography: absolute quantitation of rest and dobutamine myocardial blood flow and correlation with cardiac work and percent diameter stenosis in patients with and without coronary artery disease.

OBJECTIVES: This study sought to measure myocardial blood flow at rest and during dobutamine infusion and to correlate flow with cardiac work and severity of coronary artery disease. BACKGROUND: Dobutamine is used with cardiac imaging to induce possible ischemia in patients with known or suspected coronary artery disease. Positron emission tomography permits noninvasive quantitation of myocardial blood flow. METHODS: Fifteen patients with quantitative coronary arteriography were studied at rest and during dobutamine infusion using nitrogen-13 ammonia flow imaging with positron emission tomography. Myocardial blood flow was determined in regions corresponding to the three major coronary arteries for myocardium with and without dobutamine flow defects and with and without a > 50% diameter stenosis. RESULTS: Eight patients had at least one dobutamine flow defect; four of whom had a previous myocardial infarction. One patient with > 50% diameter stenosis had no flow defects, and one with < 50% diameter stenosis (48%) had one defect. Dobutamine significantly increased myocardial blood flow in regions with and without a dobutamine flow defect or > 50% diameter stenosis, with a greater increase when a defect or > 50% diameter stenosis was not present. Rest and dobutamine flows in regions without > 50% diameter stenosis were 0.93 +/- 0.20 (mean +/- SD) and 2.16 +/- 0.52 ml/min per g (p < 0.01), respectively. The corresponding flows in regions without a defect were 0.94 +/- 0.21 and 2.17 +/- 0.53 ml/min per g (p < 0.01), respectively. This 2, 4-fold increase in flow was significantly correlated (p < 0.001) with a 2.2-fold increase in rate-pressure product induced by dobutamine. The rest and dobutamine flows for regions subtended by a vessel with > 50% diameter stenosis were 0.70 +/- 0.33 and 1.20 +/- 0.54 ml/min per g (p < 0.05), respectively, whereas the corresponding values for regions with a dobutamine flow defect were 0.69 +/- 0.33 ml/min per g at rest and 1.23 +/- 0.54 ml/min per g during dobutamine (p < 0.05). Dobutamine increased flow inversely proportional to percent diameter stenosis. The rest flow for regions with a dobutamine flow defect were not significantly different from that in regions without defects. CONCLUSIONS: Dobutamine resulted in a significant increase in myocardial blood flow that correlated significantly with both increased cardiac work and degree of stenosis.

Adult↗
PubMed1995

Changes in the carboxyl-terminal propeptide of type I procollagen and other markers of bone formation upon five days of bed rest.

This study was performed in order to investigate the influence of skeletal unloading on the serum concentration of the carboxyl-terminal propeptide of type I procollagen (sPICP) and other markers of bone formation. Blood samples were taken every third hour from nine healthy premenopausal women (22-29 years) in two 24 h studies, before and at the end of five days of bed rest. Furthermore, a set of samples were taken 12 h apart after three days of bed rest. We measured sPICP, the serum concentration of intact and N-terminal-Mid fragment osteocalcin (sOC), and the serum concentration of alkaline phosphatase (sAP). During the five days of bed rest a gradual increase in sOC was observed, while sPICP gradually decreased. sAP was unchanged. Five days of best rest resulted in the following overall changes in the 24 h mean values: sPICP: -14% (p = 0.002); sOC: +9% (p = 0.009); sAP: -1% (not significant). The circadian patterns did not change significantly after bed rest. It is puzzling that the changes in the bone formation markers are of different magnitude, and for sPICP and sOC even in opposite directions. The increase in sOC may be caused by an increase in OC secretion by the osteoblasts or a release of bone-incorporated OC from resorbing sites; the accompanying decrease in sPICP may indicate that bone formation is actually transiently decreased after short term bed rest.

Adult↗
PubMed2006

Resting energy expenditure and metabolic changes after lung volume reduction surgery for emphysema.

BACKGROUND: Oxygen consumption volume (VO2) and resting energy expenditure are increased in emphysema because of impaired respiratory function and mechanics, with greater oxygen cost of breathing and altered metabolism. We hypothesized that lung volume reduction surgery may improve energy expenditure and metabolism. METHODS: In this 1-year prospective study, 30 patients with moderate-to-severe emphysema underwent bilateral lung volume reduction surgery; 28 similar patients, who refused operation, followed a standard respiratory rehabilitation program. Oxygen consumption volume and resting energy expenditure, both corrected for fat-free mass, VO2 proportion of respiratory muscles (%VO2Resp), respiratory quotient, and energy substrate oxidation were determined by using a calorimetric chamber with indirect methods. RESULTS: Only after surgery significant improvements resulted in 1-second forced expiratory volume (+20.4%, p = 0.009), residual volume (-24.8%, p = 0.001), diffusion-lung carbon-monoxide (+18.4%, p = 0.008), body mass index (+5.5%, p = 0.01), resting energy expenditure (-8.2%, p = 0.006), and %VO2Resp (-44.1%, p = 0.0008) with increase in respiratory quotient (0.79 versus 0.84, p = 0.03) and conversion from prevalent lipid (44.6% versus 34.3%, p = 0.0007) to prevalent carbohydrate (25.2% versus 42.2%, p = 0.0006) metabolism. Thirteen operated on patients discontinued oral steroids, showing the most significant improvements. The remaining 17 experienced significant changes compared with the rehabilitation group despite oral steroids (resting energy expenditure -7.0% versus +4.1%, and %VO2Resp -34.0% versus +0.7%, p = 0.001). Decrease of resting energy expenditure and %VO2Resp correlated with reduction of residual volume (p = 0.02 and p = 0.001) and increment of body mass index (p = 0.03 and p = 0.004). CONCLUSIONS: Lung volume reduction surgery significantly decreased %VO2Resp and resting energy expenditure over respiratory rehabilitation and despite oral steroid therapy. Substrate oxidation changed from prevalent lipid to prevalent carbohydrate. Correlations with residual volume and nutritional status suggest that restoration of respiratory mechanics reduces energy expenditure and approximates metabolism to normal.

Aged↗
PubMed2007

Resting-state functional connectivity in major depression: abnormally increased contributions from subgenual cingulate cortex and thalamus.

BACKGROUND: Positron emission tomography (PET) studies of major depression have revealed resting-state abnormalities in the prefrontal and cingulate cortices. Recently, fMRI has been adapted to examine connectivity within a specific resting-state neural network--the default-mode network--that includes medial prefrontal and anterior cingulate cortices. The goal of this study was to examine resting-state, default-mode network functional connectivity in subjects with major depression and in healthy controls. METHODS: Twenty-eight subjects with major depression and 20 healthy controls underwent 5-min fMRI scans while resting quietly. Independent component analysis was used to isolate the default-mode network in each subject. Group maps of the default-mode network were compared. A within-group analysis was performed in the depressed group to explore effects of depression refractoriness on functional connectivity. RESULTS: Resting-state subgenual cingulate and thalamic functional connectivity with the default-mode network were significantly greater in the depressed subjects. Within the depressed group, the length of the current depressive episode correlated positively with functional connectivity in the subgenual cingulate. CONCLUSIONS: This is the first study to explore default-mode functional connectivity in major depression. The findings provide cross-modality confirmation of PET studies demonstrating increased thalamic and subgenual cingulate activity in major depression. Further, the within-subject connectivity analysis employed here brings these previously isolated regions of hypermetabolism into the context of a disordered neural network. The correlation between refractoriness and subgenual cingulate functional connectivity within the network suggests that a quantitative, resting-state fMRI measure could be used to guide therapy in individual subjects.

Adult↗
PubMed2005

Self-referential reflective activity and its relationship with rest: a PET study.

This study used positron emission tomography (PET) to identify the brain substrate of self-referential reflective activity and to investigate its relationship with brain areas that are active during the resting state. Thirteen healthy volunteers performed reflective tasks pertaining to three different matters (the self, another person, and social issues) while they were scanned. Rest scans were also acquired, in which subjects were asked to simply relax and not think in a systematic way. The mental activity experienced during each scan was assessed with rating scales. The results showed that, although self-referential thoughts were most frequent during the self-referential task, some self-referential reflective activity also occurred during rest. Compared to rest, performing the reflective tasks was associated with increased blood flow in the dorsomedial prefrontal cortex, the left anterior middle temporal gyrus, the temporal pole bilaterally, and the right cerebellum; there was a decrease of blood flow in right prefrontal regions and in medial and right lateral parietal regions. In addition, the ventromedial prefrontal cortex (VMPFC) (1) was more active during the self-referential reflective task than during the other two reflective tasks, (2) showed common activation during rest and the self-referential task, and (3) showed a correlation between cerebral metabolism and the amount of self-referential processing. It is suggested that the VMPFC is crucial for representing knowledge pertaining to the self and that this is an important function of the resting state.

Adult↗
PubMed2002

Usefulness of rest and low-dose dobutamine wall motion scores in predicting survival and benefit from revascularization in patients with ischemic cardiomyopathy.

This study examined the value of wall motion scores at rest and with low- and high-dose dobutamine infusion for prediction of outcome and benefit from revascularization in patients with ischemic cardiomyopathy. Follow-up was obtained in 139 patients with ischemic cardiomyopathy who had echocardiography at rest, and during low- (10 microg/kg/min) and high-dose dobutamine (maximal dose 50 microg/kg/min) infusion. Both rest and low-dose wall motion scores were multivariate predictors of cardiac death, but ischemia and peak dose scores were not predictors. Rest scores risk stratified patients into 3 groups: score (1.00 to 1.99) with 11% cardiac death; score (2.00 to 2.49) with 30% death; and score > or =2.50 with 47% death. One third of patients with rest scores > or =2.50 had improvement in scores to < 2.50 with low-dose dobutamine. Their frequency of cardiac death was reduced to 23% compared with 60% (p = 0.04) in those who remained with low-dose scores > or =2.50. Low-dose scores also identified those who benefited from revascularization. In patients with low-dose scores (1.00 to 1.99), the frequency of cardiac death was marginally lower in revascularized than nonrevascularized patients (10% vs 21%, p = 0.28). In patients with scores (2.00 to 2.49), revascularized patients had a significantly lower frequency of cardiac death than nonrevascularized patients (15% vs 41%, p < 0.05). The frequency of death in those with low-dose scores > or =2.50 was very high in both revascularized (75%) and nonrevascularized (56%, p = 0.42) patients. Thus, rest and low-dose wall motion scores enable risk stratification of patients with ischemic cardiomyopathy and identify those who do and do not benefit from revascularization.

Adrenergic beta-Agonists↗
PubMed2000

Comparative rest and exercise hemodynamics of 23-mm stentless versus 23-mm stented aortic bioprostheses.

BACKGROUND: The hemodynamic superiority of stentless valves at rest has been generally accepted, but there is a lack of studies on exercise hemodynamics. METHODS: We assessed aortic valve hemodynamics at rest and during exercise in 10 patients with a 23-mm stentless aortic bioprosthesis (Medtronic Freestyle; Medtronic Europe SA/NV, St. Stevens Woluwe, Belgium), in 10 patients with a 23-mm stented aortic bioprosthesis (Carpentier-Edwards, SAV, model 2650; Baxter Edwards AG, Horw, Switzerland), and in 10 healthy volunteers (control group) by means of Doppler echocardiography. RESULTS: Gradients at rest and gradients on comparable maximum exercise levels were significantly lower in patients with stentless valves compared to those with stented valves (rest: 6 +/- 2/11 +/- 4 mm Hg [mean/peak] versus 12 +/- 3/21 +/- 10 mm Hg; exercise: 9 +/- 3/18 +/- 6 mm Hg [mean/peak] versus 22 +/- 8/40 +/- 11 mm Hg). Patients with stentless valves revealed, in comparison to healthy young men, significantly higher gradients, but the small gradient difference of 3/7 mm Hg (mean/peak) at rest remained nearly unchanged throughout the exercise protocol (4/8 mm Hg [mean/peak] at 25 W, 4/9 mm Hg at 50 W and 4/9 mm Hg at 75 W). In contrast, the gradient difference between patients with stented and stentless valves increased significantly from one exercise level to the next (6/12 mm Hg [mean/peak] at rest, 8/14 mm Hg at 25 W, 12/17 mm Hg at 50 W, and 15/25 mm Hg at 75 W). CONCLUSIONS: A stentless aortic bioprosthesis seems to be an appropriate aortic valve substitute, especially in patients who perform regular physical exercise.

Aged↗
PubMed2003

Skeletal muscle interleukin-6 and tumor necrosis factor-alpha release in healthy subjects and patients with type 2 diabetes at rest and during exercise.

To examine the influence of type 2 diabetes on cytokine release from the leg at rest and during exercise, 9 male type 2 diabetics (D) and 8 age-, gender-, Vo2peak-, weight- and body mass index (BMI)-matched control subjects (C) were studied before and after 25 minutes of supine bicycle exercise at 60% Vo2peak. Blood samples were obtained from a femoral artery and vein from 1 limb, and plasma was analyzed for glucose and the cytokines, interleukin (IL)-6 and tumor necrosis factor (TNF)-alpha. Leg blood flow (LBF) was measured by thermodilution in the femoral vein, and net leg IL-6, TNF-alpha, and glucose balance were calculated as the product of LBF and femoral arteriovenous (fa-v) glucose, IL-6, and TNF-alpha difference. Arterial plasma glucose and IL-6 were higher (P<.05) at rest in D compared with C, but there were no differences in arterial TNF-alpha concentrations at rest when comparing groups. Despite measurable arterial levels of both IL-6 and TNF-alpha in both groups at rest, there was not net leg release of either cytokine at rest. Exercise increased (P<.05) IL-6 release and glucose uptake in both D and C, and contracting leg glucose uptake was similar when comparing D with C. While not significant, there was a trend (P=.1) for augmented exercise-induced IL-6 release in D compared with C. In contrast, exercise did not result in TNF-alpha release in either D or C. These data demonstrate that basal circulating TNF-alpha is not elevated in patients with type 2 diabetes when matched for BMI with control subjects. The results also suggest that neither type 2 diabetic nor healthy skeletal muscle releases these cytokines at rest, indicating that organs other than skeletal muscle contribute to the elevated basal IL-6 in type 2 diabetics. In contrast with IL-6, exercise does not result in the release of TNF-alpha from the contracting limbs of either healthy subjects or patients with type 2 diabetes.

Adult↗
PubMed2002

Resistance to aspirin in vitro at rest and during exercise in patients with angiographically proven coronary artery disease.

BACKGROUND: Acetylsalicylic acid, or aspirin, is widely used in secondary prevention of coronary artery diseases, but the inhibition of platelet aggregation is not uniform in all individuals. OBJECTIVE: To investigate the prevalence of aspirin resistance at rest and during exercise in coronary artery disease patients. MATERIALS AND METHODS: Fifty patients with stable coronary artery disease were prospectively studied. All patients received aspirin (75-300 mg/day for >1 month) and no other antiplatelet therapy. Aspirin resistance was studied, at rest and immediately after a stress test, using the standardized platelet function analyzer (PFA-100(R), Dade-Behring). Aspirin resistance was defined as a normal collagen/epinephrine closure time (<186 s). RESULTS: Ten patients (20%) were aspirin-resistant at rest. Out of the 40 patients who were aspirin-sensitive at rest, 9 (22%) were aspirin-resistant immediately after the exercise stress test. There were no differences in aspirin sensitivity regarding gender, age, diabetes, hypertension, dyslipidemia, platelet count, medical treatment or number of the coronary arteries involved. CONCLUSIONS: Aspirin resistance is detected, at rest, in 20% of our patients with stable coronary artery disease. Aspirin treatment does not seem to protect against exercise-induced platelet activation in 22% of such patients, despite aspirin sensitivity at rest.

Aged↗
PubMed2002

Fluid and salt supplementation effect on body hydration and electrolyte homeostasis during bed rest and ambulation.

Bed rest (BR) induces significant urinary and blood electrolyte changes, but little is known about the effect of fluid and salt supplements (FSS) on catabolism, hydration and electrolytes. The aim was to measure the effect of FSS on catabolism, body hydration and electrolytes during BR. Studies were done during 7 days of a pre-bed rest period and during 30 days of a rigorous bed rest period. Thirty male athletes aged, 24.6 +/- 7.6 years were chosen as subjects. They were divided into three groups: unsupplemented ambulatory control subjects (UACS), unsupplemented bed rested subjects (UBRS) and supplemented bed rested subjects (SBRS). The UBRS and SBRS groups were kept under a rigorous bed rest regime for 30 days. The SBRS daily took 30 ml water per kg body weight and 0.1 sodium chloride per kg bodyweight. Plasma sodium (Na), potassium (K), calcium (Ca) and magnesium (Mg) levels, urinary Na, K, Ca and Mg excretion, plasma osmolality, plasma protein level, whole blood hemoglobin (Hb) and hematocrit (Hct) level increased significantly (p < or = 0.05), while plasma volume (PV), body weight, body fat, peak oxygen uptake, food and fluid intake decreased significantly (p < or = 0.05) in the UBRS group when compared with the SBRS and UACS groups. In contrast, plasma and urinary electrolytes, osmolality, protein level, whole blood Hct and Hb level decreased significantly (p < or = 0.05), while PV, fluid intake, body weight and peak oxygen uptake increased significantly (p < or = 0.05) in the SBRS group when compared with the UBRS group. The measured parameters did not change significantly in the UACS group when compared with their baseline control values. The data indicate that FSS stabilizes electrolytes and body hydration during BR, while BR alone induces significant changes in electrolytes and body hydration. We conclude that FSS may be used to prevent catabolism and normalize body hydration status and electrolyte values during BR.

Adaptation, Physiological↗
PubMed2000

The ice test versus the rest test in myasthenia gravis.

OBJECTIVE: To compare the ice test with the rest test in subjects with myasthenic and nonmyasthenic ptosis. DESIGN: Randomized, noninterventional trial. PARTICIPANTS: (1) Ten subjects with ptosis from previously undiagnosed myasthenia gravis. (2) Fifteen subjects with nonmyasthenic ptosis. METHODS: Application of ice compared with rest. MAIN OUTCOME MEASURES: Improvement in eyelid elevation in millimeters after the application of a surgical glove filled with ice or cotton. RESULTS: In myasthenic subjects, the median improvement of ptosis with the rest test was 2 mm and with the ice test was 4.5 mm. The difference between the rest and ice tests is significant (P: < 0.001). There was no improvement in ptosis in nonmyasthenic subjects with either test. CONCLUSION: In myasthenic ptosis, improvement in eyelid elevation after the ice test is in part caused by rest. The ice test significantly improves ptosis more than rest alone does.

Adolescent↗
PubMed2000

Autonomic dysregulation in panic disorder and in post-traumatic stress disorder: application of power spectrum analysis of heart rate variability at rest and in response to recollection of trauma or panic attacks.

Power spectral analysis (PSA) of heart rate variability (HRV) offers reliable assessment of cardiovascular autonomic responses, providing a 'window' onto the interaction of peripheral sympathetic and parasympathetic tone. Alterations in HRV are associated with various physiological and pathophysiological processes, and may contribute to morbidity and mortality. Previous studies of posttraumatic stress disorder (PTSD) found lower resting HRV in patients compared to controls, suggesting increased sympathetic and decreased parasympathetic tone. This article describes the analysis of HRV at rest and after psychological stress in panic disorder (PD) patients, in an enlarged sample of PTSD patients, and in healthy control subjects. Standardized heart rate (HR) analysis was carried out in 14 PTSD patients, 11 PD patients and 25 matched controls. ECG recordings were made while subjects were resting ('rest 1'), while recalling the trauma implicated in PTSD, or the circumstances of a severe panic attack, as appropriate ('recall'), and again while resting ('rest 2'). Controls were asked to recall a stressful life event during recall. While both patient groups had elevated HR and low frequency (LF) components of HRV at baseline (suggesting increased sympathetic activity), PTSD patients, unlike PD patients and controls, failed to respond to the recall stress with increases in HR and LF. HRV analysis demonstrates significant differences in autonomic regulation of PTSD and PD patients compared to each other and to control subjects. HRV analysis may augment biochemical studies of peripheral measures in these disorders.

Adult↗
PubMed1998

Free plasma catecholamines in spinal cord injured persons with different injury levels at rest and during exercise.

Spinal cord lesion leads to an interruption of pathways from brain to the peripheral sympathetic nervous system, which results in pathological changes in sympathetic innervation. Free epinephrine (E), norepinephrine (NE) and dopamine (DA) were measured in 30 tetraplegics (TETRA), 15 high-lesion paraplegics (T1 and T4, HPARA), 15 paraplegics with injuries between T5 and T10 (MPARA), 15 low-lesion paraplegics (below T10, LPARA) and 16 non-handicapped control persons (C) at rest, at 60 and 100% of maximal oxygen consumption during graded wheelchair ergometry (WCE). The TETRA showed significant lower E and NE levels at rest and only slight increases during physical exercise. The E and NE concentrations of the paraplegics with a lesion below T5 were significantly higher than those of the high-lesion paraplegics, as well as those of the control persons at every point in the study. All paraplegics and the control persons showed, at submaximal and maximal exercise, a significant increase in NE. Only a slight increase in E in HAPRA was shown. No differences were found at rest and during exercise in E and NE levels in the MPARA and LPARA. No significant differences were found in the dopamine concentration at rest or during exercise for any of the groups. In summary, different levels of lesion and the resulting interruption to sympathetic pathways in the spinal cord are decisive factors in the degree of impairment of sympathetic innervation in SCI persons. Tetraplegics show less preganglionic resting activity because of interruption of impulses from central centers and no considerable stimulation of the sympathetic nervous system during maximal exercise. Individuals with high paraplegia have a partial impairment of catecholamine release, especially of epinephrine, at rest and during exercise. Paraplegics with a lesion level below T5 showed an augmented basal and exercise-induced upper spinal thoracic sympathetic activity in comparison to control persons.

Adult↗
PubMed1986

Effects of nifedipine on arterial oxygenation at rest and during exercise in patients with stable angina.

The effects of nifedipine on arterial oxygenation and hemodynamics were studied at rest and during bicycle exercise in 12 men (mean age 55 years, range 41 to 67) with stable exertional angina. The study was conducted double-blind on 2 days, 1 week apart, using a placebo-controlled crossover design. On each day, measurements at rest were made before and 20 minutes after 20 mg sublingual nifedipine or placebo and were followed by measurements made during exercise. Compared with placebo, nifedipine reduced mean arterial pressure, systemic vascular resistance and pulmonary vascular resistance, and increased heart rate and cardiac output at rest and during exercise. It did not alter mean pulmonary artery or pulmonary artery wedge pressures at rest, but decreased them during exercise. Nifedipine decreased arterial oxygen tension (PaO2) from 96 +/- 10 to 90 +/- 13 mm Hg (p less than 0.05) at rest and from 99 +/- 11 to 92 +/- 12 mm Hg (p less than 0.005) at submaximal exercise (33 +/- 21 W), but did not alter it (100 +/- 12 versus 100 +/- 16 mm Hg, p = NS) at maximal exercise (68 +/- 30 W). The reduction in PaO2 was not due to alveolar hypoventilation, because nifedipine did not alter arterial carbon dioxide tension, or to changes in mixed venous oxygen tension, which nifedipine increased at rest (39 +/- 2 versus 43 +/- 3 mm Hg, p less than 0.001) and during submaximal exercise (31 +/- 4 versus 33 +/- 4 mm Hg, p less than 0.03) and maximal exercise (27 +/- 3 versus 31 +/- 3 mm Hg, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Myocardial blood flow at rest and contractile reserve in patients with chronic coronary artery disease and left ventricular dysfunction.

BACKGROUND: The mechanisms that determine chronic left ventricular dysfunction in coronary artery disease (in particular, critical reductions in coronary artery blood flow leading to hibernating myocardium) may affect the ability of the myocardium to respond to inotropic stimulation with dobutamine. This study was designed to investigate the relationship between resting myocardial blood flow and contractile reserve in patients with coronary artery disease and chronic left ventricular dysfunction. METHODS AND RESULTS: Twenty-three patients (21 men and 2 women; age 61 +/- 9 years) underwent transesophageal echocardiography during infusion of dobutamine (2.5 microg/kg to 40 microg/kg per minute) and positron emission tomography (PET) with 150-water (9 patients) or 13N-ammonia (14 patients). Systolic wall thickening at each dose of dobutamine and resting myocardial blood flow were quantitatively analyzed in 8 anatomically matched regions at mid-ventricular level. Myocardial regions with preserved contraction had higher blood flow compared with regions with basal dyssynergy (0.99 +/- 0.3 vs 0.65 +/- 0.3 mL/min/gm; P < .0001). Among myocardial regions with preserved resting contraction, no relation was observed between blood flow and the response to dobutamine (r = 0.06). In contrast, among myocardial regions with diminished resting contraction, a significant correlation was observed between resting blood flow and contractile reserve (r = 0.53; P < .0001). The maximum increase in percent systolic wall thickening with dobutamine was 32.8% +/- 14% in regions with normal blood flow, 21.5% +/- 17% in regions with mildly to moderately reduced blood flow, and 10.7% +/- 10% in regions with severely reduced blood flow (P < .0001). CONCLUSIONS: These findings emphasize the importance of resting myocardial blood flow for the preservation of contractile reserve in patients with coronary artery disease and left ventricular dysfunction. Because a positive inotropic response to dobutamine is more likely to occur in dyssynergic regions with preserved rather than reduced myocardial blood flow, regional perfusion may determine in which circumstances dobutamine echocardiography contributes to the assessment of myocardial viability.

Chronic Disease↗
PubMedDate not supplied

Comparison of acute rest myocardial perfusion imaging and serum markers of myocardial injury in patients with chest pain syndromes.

BACKGROUND: Newer diagnostic modalities such as serum markers and acute rest myocardial perfusion imaging (MPI) have been evaluated diagnostically in patients with chest pain in the emergency department (ED), but never concurrently. We compared these two modalities in distinguishing patients in the ED with symptomatic myocardial ischemia from those with non-cardiac causes. METHODS: Serum markers and acute technetium-99m sestamibi/tetrofosmin rest MPI were obtained in 75 patients admitted to the ED with chest pain and nondiagnostic electrocardiograms. Venous samples were drawn at admission and 8 to 24 hours later for total creatine kinase, CK-MB fraction, troponin T, troponin I, and myoglobin. Three nuclear cardiologists performed blinded image interpretation. Coronary artery disease (CAD) was confirmed either by diagnostic testing or by the occurrence of myocardial infarction (MI). RESULTS: Acute rest MPI results were abnormal in all 9 patients with MI. An additional 26 patients had objective evidence of CAD confirmed by diagnostic testing. The sensitivity of acute rest MPI for objective evidence of CAD was 73%. Serum troponin T and troponin I were highly specific for acute MI but had low sensitivity at presentation. Individual serum markers had very low sensitivity for symptomatic myocardial ischemia alone. In the multivariate regression model, only acute rest MPI and diabetes were independently predictive of CAD. CONCLUSION: At the time of presentation and 8 to 24 hours later, acute rest MPI has a better sensitivity and similar specificity for patients with objective evidence of CAD when compared with serum markers.

Biomarkers↗
PubMed2004

Compliance among general practitioners in France with recommendations not to prescribe bed rest for acute low back pain.

UNLABELLED: Acute low back pain is a very common reason for general practitioner visits. OBJECTIVE: To evaluate practices among French general practitioners regarding the prescription of bed rest in patients with low back pain. METHODS: 2000 general practitioners were to include the first three patients presenting within the first 3 d of onset of acute low back pain without nerve root pain. The characteristics of the pain, social and demographic characteristics of the patients, and treatments prescribed by the physicians were recorded. RESULTS: 5355 patients were included, of whom more than half had a history of one or more episodes of low back pain. The mean pain severity score on a 100-mm visual analog scale was 57.2 +/- 22.7 mm. Bed rest was recommended to 27.6% of the patients, for a mean duration of 4.4 d. Patients to whom bed rest was recommended were significantly more likely than the other patients to have chronic low back pain (32.1% vs. 26.5%) and received a greater number of medications. Bed rest was associated with significantly poorer outcomes in the multivariable analysis adjusting for confounding factors. CONCLUSION: Recommendations to avoid bed rest in patients with acute low back pain are widely followed in France. Furthermore, our results confirm that bed rest is associated with poorer outcomes.

Adult↗
PubMed1985

Bed rest in twin pregnancy.

A total of 146 twin pregnancies were studied to evaluate the importance of bed rest. A significantly reduced frequency of preterm delivery was found after bed rest in hospital as compared to bed rest at home or no bed rest at all. An increase in gestational age and in birth weight was seen after bed rest. No effect was found on the intrauterine increase of fetal weight per time. Early routine ultrasound is recommended, so that effective bed rest may be instituted in due time.

Bed Rest↗