Subject(s)
Ajmaline/adverse effects , Anti-Arrhythmia Agents/adverse effects , Brugada Syndrome/drug therapy , Brugada Syndrome/genetics , NAV1.5 Voltage-Gated Sodium Channel/genetics , Adolescent , Adult , Brugada Syndrome/diagnosis , Child , Contraindications , Electrocardiography , Family Health , Female , Humans , Male , Middle Aged , Pedigree , Young AdultABSTRACT
INTRODUCTION: Human placental stem villi (PSV) present contractile properties. We studied the role of actin-myosin cross bridges (CBs) and the effects of NO-cGMP pathway modulators in the PSV contraction and relaxation. METHODS: In vitro contractile properties were investigated in 71 PSV from term human placentas studied according to their long axis. Contraction was induced by both KCl and electrical tetanic stimulation. Relaxation was induced by inhibiting the CB cycle with either 2,3-butanedione monoxime (BDM) or blebbistatin (BLE) and by activating the NO-cGMP pathway with isosorbide dinitrate (ISDN), sildenafil (SIL) or ISDN + SIL. RESULTS: PSV tension slowly increased by 140% of the basal tone after KCl exposure and by 85% after tetanus. The addition of BDM, BLE, ISDN, SIL and ISDN + SIL induced a relaxation of PSV, the overall time course of relaxation (in s) was respectively (means ± SD) 3412 ± 1904, 14,250 ± 3095*, 3813 ± 1383, 2883 ± 1188 and 2440 ± 477; significantly longer in BLE compared with BDM, ISDN, SIL and ISDN + SIL:*p < 0.001). the overall time course of relaxation (in s) was respectively (means ± SD) 3412 ± 1904, 14,250 ± 3095*, 3813 ± 1383, 2883 ± 1188 and 2440 ± 477; significantly longer in BLE compared with BDM, ISDN, SIL and ISDN + SIL:*p < 0.001). These relaxation kinetics were particularly slow. Other relaxation parametres, i.e., maximum lengthening, -peak dT/dt, and resting tension, did not differ between these 5 subgroups. DISCUSSION AND CONCLUSION: Isolated human PSV were able to contract after both KCl exposure and tetanus. This increase in contractility was reversed by inhibiting the CB cycle with BDM or BLE and by stimulating the NO-cGMP pathway with ISDN or SIL. The association ISDN + SIL did not potentiate the relaxing processes.
Subject(s)
Actins/physiology , Chorionic Villi/physiology , Cyclic GMP/physiology , Myosins/physiology , Nitric Oxide/physiology , Second Messenger Systems , Actins/antagonists & inhibitors , Actins/chemistry , Chorionic Villi/chemistry , Chorionic Villi/drug effects , Cyclic GMP/agonists , Cyclic GMP/antagonists & inhibitors , Diacetyl/analogs & derivatives , Diacetyl/pharmacology , Electric Stimulation , Enzyme Inhibitors/pharmacology , Female , Heterocyclic Compounds, 4 or More Rings/pharmacology , Humans , In Vitro Techniques , Isosorbide Dinitrate/pharmacology , Kinetics , Myosins/antagonists & inhibitors , Myosins/chemistry , Nitric Oxide/agonists , Nitric Oxide/antagonists & inhibitors , Nitric Oxide Donors/pharmacology , Piperazines/pharmacology , Pliability/drug effects , Potassium Chloride/metabolism , Pregnancy , Protein Structure, Quaternary , Purines/pharmacology , Second Messenger Systems/drug effects , Sildenafil Citrate , Sulfones/pharmacology , Term BirthABSTRACT
Peroxisome proliferator activated receptor alpha (PPAR alpha) regulates fatty acid beta-oxidation (FAO) and plays a central role in the metabolic and energetic homeostasis of striated muscles. The thermodynamic consequences of the absence of PPAR alpha were investigated in diaphragm muscle of PPAR alpha knockout mice (KO). Statistical mechanics provides a powerful tool for determining entropy production, which quantifies irreversible chemical processes generated by myosin molecular motors and which is the product of thermodynamic force A/T (chemical affinity A and temperature T) and thermodynamic flow (myosin crossbridge (CB) cycle velocity upsilon). The behavior of both wild type (WT) and KO diaphragm was shown to be near-equilibrium and in a stationary state, but KO was farther from equilibrium than WT. In KO diaphragm, a substantial decrease in contractile function was associated with an increase in both A/T and upsilon and with profound histological injuries such as contraction band necrosis. There were no changes in PPAR delta and gamma expression levels or myosin heavy chain (MHC) patterns. In KO diaphragm, a marked increase in entropy production (A/T x upsilon) accounted for major thermodynamic dysfunction and a dramatic increase in irreversible chemical processes during the myosin CB cycle.
Subject(s)
Diaphragm/physiopathology , PPAR alpha/deficiency , Animals , Body Weight , Diaphragm/metabolism , Diaphragm/pathology , Entropy , Gene Expression Regulation , Male , Mice , Mice, Inbred C57BL , Mice, Knockout , Myosin Heavy Chains/analysis , Myosins/metabolism , PPAR alpha/biosynthesis , PPAR alpha/genetics , PPAR delta/biosynthesis , PPAR delta/genetics , PPAR gamma/biosynthesis , PPAR gamma/genetics , Protein Isoforms/analysis , RNA, Messenger/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , ThermodynamicsABSTRACT
Statistical mechanics provides the link between microscopic properties of matter and its bulk properties. The grand canonical ensemble formalism was applied to contracting rat skeletal muscles, the soleus (SOL, n = 30) and the extensor digitalis longus (EDL, n = 30). Huxley's equations were used to calculate force (pi) per single crossbridge (CB), probabilities of six steps of the CB cycle, and peak muscle efficiency (Eff(max)). SOL and EDL were shown to be in near-equilibrium (CB cycle affinity 2.5 kJ/mol) and stationary state (linearity between CB cycle affinity and myosin ATPase rate). The molecular partition function (z) was higher in EDL (1.126+/-0.005) than in SOL (1.050+/-0.003). Both pi and Eff(max) were lower in EDL (8.3+/-0.1 pN and 38.1+/-0.2%, respectively) than in SOL (9.2+/-0.1 pN and 42.3+/-0.2%, respectively). The most populated step of the CB cycle was the last detached state (D3) (probability P(D3): 0.890+/-0.004 in EDL and 0.953+/-0.002 in SOL). In each muscle group, both pi and Eff(max) linearly decreased with z and statistical entropy and increased with P(D3). We concluded that statistical mechanics and Huxley's formalism provided a powerful combination for establishing an analytical link between chemomechanical properties of CBs, molecular partition function and statistical entropy.
Subject(s)
Models, Statistical , Molecular Motor Proteins/physiology , Muscle, Skeletal/physiology , Myosins/metabolism , Adenosine Triphosphatases/metabolism , Animals , Isometric Contraction/physiology , Models, Biological , RatsABSTRACT
Congestive cardiac failure could be as important as cardiac arrhythmias in the natural history of arrhythmogenic right ventricular dysplasia. This can be related to the progressive replacement of myocardium by fat and fibrosis of the right ventricle. The left ventricle may also be involved by the same disease process. Moreover, inflammation can be superimposed on ARVD, resulting in a wide spectrum of clinical presentation which can mimick idiopathic dilated cardiomyopathy. Right ventricular cardiac failure has been controlled by anterior dynamic cardiomyoplasty.
Subject(s)
Arrhythmogenic Right Ventricular Dysplasia/complications , Heart Failure/etiology , Arrhythmogenic Right Ventricular Dysplasia/diagnosis , Arrhythmogenic Right Ventricular Dysplasia/pathology , Cardiomyopathy, Dilated/diagnosis , Diagnosis, Differential , Disease Progression , Humans , InflammationABSTRACT
Skin cancers are a rising menace as their incidence increases, attributed in part to increasing ultraviolet radiation exposure. This increasing problem has stimulated efforts to devise useful preventive approaches. The uncertain efficacy of exhortations to avoid sun exposure and to use protective clothing and sunscreens to reduce damage when exposed argue for the development of an oral chemopreventive agent. Bickers and others have studied the effects and mechanisms of tea and of its putative active components on inhibition of skin cancer in experimental models. To continue this work, we have studied the effects of oral green tea and black tea on a new model of ultraviolet-induced skin carcinogenesis - the development of basal cell carcinomas in ptc1+/- mice. To our surprise, we have found that tea preparations which others have used to prevent squamous cell carcinoma formation in mice fail to inhibit basal cell carcinogenesis in our model, suggesting that prevention of this cancer may require special, tumor-specific approaches.
Subject(s)
Carcinoma, Basal Cell/prevention & control , Oncogene Proteins, Fusion/genetics , Phytotherapy , Skin Neoplasms/prevention & control , Tea , Alleles , Animals , Carcinoma, Basal Cell/genetics , Carcinoma, Basal Cell/pathology , Female , Male , Mice , Mice, Knockout , Mutation/genetics , Protein-Tyrosine Kinases , Skin Neoplasms/genetics , Skin Neoplasms/pathologyABSTRACT
In heart transplant recipients (HTR), short-term systolic blood pressure variability is preserved, whereas heart rate variability is almost abolished. Heart period is the sum of left ventricular ejection time (LVET) and diastolic time (DT). In the present time-domain prospective study, we tested the hypothesis that short-term fluctuations in aortic pulse pressure (PP) in HTR were related to fluctuations in LVET. Seventeen male HTR (age 48 +/- 6 yr) were studied 16 +/- 11 mo after transplantation. Aortic root pressure was obtained over a 15-s period using a micromanometer both at rest (n = 17) and following the cold pressor test (CPT, n = 14). There was a strong positive linear relationship between beat-to-beat LVET and beat-to-beat PP in all patients at rest and in 13 of 14 patients following CPT (each P < 0.01). The slope of this relationship showed little scatter both at rest (0.34 +/- 0.07 mmHg/ms) and following CPT (0.35 +/- 0.09 mmHg/ms, P = not significant). Given the essentially fixed heart period, DT varied inversely with LVET. As a result, in 13 of 17 HTR at rest and in 12 of 14 HTR following CPT, there was a negative linear relationship between beat-to-beat PP and DT. In conclusion, our short-term time-domain study demonstrated a strong positive linear relationship between LVET and blood pressure variability in male HTR. We also identified a subgroup of HTR in whom there was a mismatch between PP and DT.
Subject(s)
Blood Pressure/physiology , Heart Transplantation/physiology , Pulse , Adult , Aorta/physiology , Cardiac Output , Diastole/physiology , Heart Rate , Humans , Male , Middle Aged , Prospective Studies , Pulmonary Circulation , Regression Analysis , Systole/physiology , Vascular Resistance , Ventricular Function, LeftSubject(s)
Aorta/physiopathology , Blood Pressure , Heart Diseases/physiopathology , Humans , MathematicsSubject(s)
Aorta/physiology , Blood Pressure Determination/methods , Blood Pressure , Adult , Female , Humans , Male , Mathematics , Prospective StudiesABSTRACT
Arrhythmogenic right ventricular dysplasia (ARVD) is a new form of cardiomyopathy probably more frequent than commonly reported. It is a rare but important cause of sudden arrhythmic death in young, otherwise healthy persons, as well as a subtle cause of congestive heart failure. It may lead to temporary incapacitation with catastrophic consequences. Proper electrocardiographic criteria, echocardiography, nuclear medicine, or magnetic resonance imaging could identify most of these individuals. With the exception of full-thickness histological examination of the right ventricular free wall, contrast ventriculography remains the most definitive standard for a positive diagnosis. The wide clinical spectrum of arrhythmogenic right ventricular cardiomyopathies/dysplasia appears to be the result of one or possibly two factors: (a) replacement of most of the right ventricular myocardium by fat and (b) genetic susceptibility to environmental agents (myocarditis). Current treatment modalities include drug therapy, catheter or surgical ablative techniques, and modern treatments of congestive heart failure. Heart transplant is exceptional. Implantable defibrillators, used alone or in combination with drug therapy, will probably play an increasing role in ARVD and related cardiomyopathies.
Subject(s)
Arrhythmogenic Right Ventricular Dysplasia/physiopathology , Adipose Tissue/pathology , Adolescent , Adult , Aged , Arrhythmogenic Right Ventricular Dysplasia/complications , Arrhythmogenic Right Ventricular Dysplasia/diagnosis , Arrhythmogenic Right Ventricular Dysplasia/pathology , Arrhythmogenic Right Ventricular Dysplasia/therapy , Contrast Media , Death, Sudden, Cardiac/etiology , Echocardiography , Electrocardiography , Genetic Predisposition to Disease , Heart Failure/etiology , Humans , Magnetic Resonance Imaging , Middle Aged , Myocarditis/pathology , Myocardium/pathologyABSTRACT
Arterial pulse pressure response during the strain phase of the Valsalva maneuver has been proposed as a clinical tool for the diagnosis of left heart failure, whereas responses of subjects with preserved systolic function have been poorly documented. We studied the relationship between the aortic pulse amplitude ratio (i.e., minimum/maximum pulse pressure) during the strain phase of the Valsalva maneuver and cardiac hemodynamics at baseline in 20 adults (42 +/- 14 yr) undergoing routine right and left heart catheterization. They were normal subjects (n = 5) and patients with various forms of cardiac diseases (n = 15), and all had a left ventricular ejection fraction >/=40%. High-fidelity pressures were recorded in the right atrium and the left ventricle at baseline and at the aortic root throughout the Valsalva maneuver. Aortic pulse amplitude ratio 1) did not correlate with baseline left ventricular end-diastolic pressure, cardiac index (thermodilution), or left ventricular ejection fraction (cineangiography) and 2) was positively related to total arterial compliance (area method) (r = 0.59) and to basal mean right atrial pressure (r = 0.57) (each P < 0.01). Aortic pulse pressure responses to the strain were not related to heart rate responses during the maneuver. In subjects with preserved systolic function, the aortic pulse amplitude ratio during the strain phase of the Valsalva maneuver relates to baseline total arterial compliance and right heart filling pressures but not to left ventricular function.
Subject(s)
Central Venous Pressure/physiology , Systole/physiology , Valsalva Maneuver/physiology , Adult , Aorta, Thoracic/physiology , Catheterization, Central Venous , Female , Heart Rate/physiology , Humans , Male , Pressoreceptors/physiology , Prospective Studies , Reflex/physiologyABSTRACT
Winged helix transcription factors play important roles in cellular differentiation and cell-specific gene expression. To define the role of the winged helix factor hepatocyte nuclear factor/forkhead homologue (HFH)-4, a targeted mutation was created in the mouse hfh-4 gene. No expression of HFH-4 was detected in hfh-4(-)/- mice by RNA blot analysis, in situ hybridization, or RT-PCR. hfh-4(-)/- mice were noted to have abnormalities of organ situs consistent with random determination of left-right asymmetry. In addition, a complete absence of cilia was noted in hfh-4(-)/- mice. The hfh-4 gene is thus essential for nonrandom determination of left-right asymmetry and development of ciliated cells. Homozygous mutant mice also exhibited prenatal and postnatal growth failure, perinatal lethality and, in some cases, hydrocephalus. RT-PCR revealed an absence of left-right dynein (lrd) expression in the embryonic lungs of hfh-4(-)/- mice, suggesting that HFH-4 may act by regulating expression of members of the dynein family of genes. The abnormalities in ciliary development and organ situs in hfh-4(-)/- mice are similar to those observed in human congenital syndromes such as Kartagener syndrome. Targeted mutation of hfh-4 thus provides a model for elucidating the mechanisms regulating ciliary development and determination of left-right asymmetry.
Subject(s)
Body Patterning/genetics , Cilia/genetics , DNA-Binding Proteins , Mutation , Phosphoproteins/deficiency , Transcription Factors/deficiency , Abnormalities, Multiple , Animals , Basic Helix-Loop-Helix Leucine Zipper Transcription Factors , Choroid Plexus/embryology , Dyneins/biosynthesis , Female , Forkhead Transcription Factors , Growth , Hepatocyte Nuclear Factor 4 , Kartagener Syndrome , Lung/embryology , Male , Mice , Nuclear Proteins/genetics , Oviducts/embryology , Phosphoproteins/genetics , Sequence Homology, Amino Acid , Testis/embryology , Transcription Factors/geneticsABSTRACT
BACKGROUND: Digital photoplethysmography is used to assess hemodynamic variability and baroreflex sensitivity. Numerous studies have critically evaluated the accuracy of the photoplethysmographic device against peripheral pressure. The aim of our study was to compare finger blood and aortic root pressure. METHODS: We prospectively compared simultaneous recordings of systolic pressure at the aortic root and finger level over three consecutive respiratory cycles in 15 patients (56+/-11 years) undergoing routine cardiac catheterization. Data were obtained at baseline, during deep breathing maneuver (0.1 Hz), and after left ventricular cineangiography. RESULTS: At baseline, systolic finger pressure overestimated systolic aortic pressure (145.2+/-22.5 vs 115.0+/-20.1 mm Hg; p<0.001). The pressure difference (30.2+/-17.0 mm Hg) was not influenced by systolic aortic pressure. There was no relationship between pressure difference and the main determinants of the pulse wave amplification phenomenon. There was a beat-to-beat relationship between finger and aortic pressure in 14 of 15 subjects (slope ranging from 0.37 to 1.70; ordinate: from -56 to +98 mm Hg). During the deep breathing maneuver and after left ventricular cineangiography, finger pressure still overestimated aortic pressure by 32.3+/-15.0 mm Hg and 38.3 13.9 mm Hg, respectively (each p<0.001). There was a beat-to-beat relationship between systolic aortic root pressure (IAoBP) and systolic finger (FBP) in 13 of 15 patients, with major scattering of both slopes and ordinates. Throughout the study, there was no predictable relationship between the level of IAoBP and pressure bias. CONCLUSIONS: As expected, FBP was almost always higher than IAoBP. Importantly, the differences in systolic pressure did not correlate with known determinants of the pulse wave amplification phenomenon. The device must be used cautiously if one wants to noninvasively track spontaneous or induced changes in IAoBP.
Subject(s)
Aorta/physiology , Blood Pressure Determination , Fingers/blood supply , Cardiac Catheterization , Cineangiography , Female , Humans , Male , Middle Aged , Photoplethysmography , Prospective Studies , Respiration , Sensitivity and Specificity , SystoleABSTRACT
On the basis of the windkessel model, the stroke volume-to-aortic pulse pressure ratio (SV/PP) has been proposed as an estimate of total arterial compliance, but recent studies have questioned this approximation. Aortic pressure was obtained at rest in 31 adults undergoing cardiac catheterization (47 +/- 14 yr): controls (n = 7), patients with dilated cardiomyopathy (n = 10), and patients with other cardiac diseases (n = 14). We calculated PP, mean aortic pressure (MAoP), heart period (T), SV (thermodilution cardiac output/heart rate), total peripheral resistance (R), total arterial compliance estimated by area method (Carea), and the time constant of aortic pressure decay in diastole (RCarea). In the overall population (n = 31), there was no significant difference between SV/PP and Carea. SV/PP was linearly related to Carea (SV/PP = 0.99Carea + 0.05; r = 0.98; P < 0.001); the slope and intercept did not differ from unity and zero, respectively. Similar results were obtained in the three subgroups. These results implied that PP/MAoP and T/RCarea were proportionally related (T/RCarea = 1.18PP/MAoP - 0.07; r = 0.96; P < 0.001). We conclude that for humans at rest 1) SV/PP gave a reliable estimate of Carea, and 2) T normalized by the time constant of aortic pressure decay in diastole was proportionally related to PP/MAoP. This last relationship could be considered an aspect of the coupling between the left ventricle and its load.
Subject(s)
Aorta/physiology , Blood Pressure , Hemodynamics , Stroke Volume , Adult , Aged , Cardiac Catheterization , Cardiomyopathy, Dilated/physiopathology , Female , Heart Diseases/physiopathology , Humans , Male , Middle Aged , Prospective Studies , Pulsatile Flow , Sensitivity and SpecificityABSTRACT
The mean blood pressure is an accurate estimate of the end-systolic aortic pressure in children. The aim of this study was: 1) to assess the relationship between the pressure at the incisura (PIAo) and the mean (MAoP) and pulse (PAoP) pressures of the supravalvular aorta in adults: and 2) to evaluate MAoP as an estimate of PIAo in adults. High fidelity pressure recordings were carried out in the supravalvular aorta in 17 men. The pressures were measured at rest in 10 consecutive beats and. In 6 subjects, during a Valsalva manoeuvre. At rest, PIAo was greater than the MAoP (109 +/- 17.9 versus 99.6 +/- 12.5 mmHg, p = 0.0001). There was a positive linear correlation between PIAo and MAoP (r = 0.93) and between PIAo and PAoP (r' = 0.77) whereas no correlation was observed between PIAo and heart rate, cardiac output or estimated total systemic arterial compliance. A beat-to-beat relationship was observed between PIAo and MAOP: 1) at rest in 16 of the 17 subjects and 2) in each subject who performed a Valsalva manoeuvre. Both at rest and during Valsalva, MAOP underestimated PIAo significantly, especially when PIAo was increased (p = 0.0001). The authors conclude that end-systolic supraaortic pressure is mainly related to the mean component of aortic pressure. MAOP slightly but constantly underestimated PIAo and this should lead to caution in assimilating MAOP to end-systolic aortic pressure in adults, especially in subjects with very high aortic pressures.
Subject(s)
Aorta , Blood Pressure , Adult , Aged , Aorta/physiology , Blood Pressure Determination , Data Interpretation, Statistical , Hemodynamics , Humans , Male , Middle Aged , Prospective Studies , Sensitivity and Specificity , Systole , Valsalva ManeuverABSTRACT
It has been suggested that pulmonary artery pressure at the end of ejection is close to mean pulmonary artery pressure, thus contributing to the optimization of external power from the right ventricle. We tested the hypothesis that dicrotic notch and mean pulmonary artery pressures could be of similar magnitude in 15 men (50 +/- 12 yr) referred to our laboratory for diagnostic right and left heart catheterization. Beat-to-beat relationships between dicrotic notch and mean pulmonary artery pressures were studied 1) at rest over 10 consecutive beats and 2) in 5 patients during the Valsalva maneuver (178 beats studied). At rest, there was no difference between dicrotic notch and mean pulmonary artery pressures (21.8 +/- 12.0 vs. 21.9 +/- 11.1 mmHg). There was a strong linear relationship between dicrotic notch and mean pressures 1) over the 10 consecutive beats studied in each patient (mean r = 0.93), 2) over the 150 resting beats (r = 0.99), and 3) during the Valsalva maneuver in each patient (r = 0.98-0.99) and in the overall beats (r = 0.99). The difference between dicrotic notch and mean pressures was -0.1 +/- 1.7 mmHg at rest and -1.5 +/- 2.3 mmHg during the Valsalva maneuver. Substitution of the mean pulmonary artery pressure by the dicrotic notch pressure in the standard formula of the pulmonary vascular resistance (PVR) resulted in an equation relating linearly end-systolic pressure and stroke volume. The slope of this relation had the dimension of a volume elastance (in mmHg/ml), a simple estimate of volume elastance being obtained as 1.06(PVR/T), where T is duration of the cardiac cycle. In conclusion, dicrotic notch pressure was of similar magnitude as mean pulmonary artery pressure. These results confirmed our primary hypothesis and indicated that human pulmonary artery can be treated as if it is an elastic chamber with a volume elastance of 1.06(PVR/T).
Subject(s)
Blood Pressure , Pulmonary Artery/physiopathology , Cardiovascular Diseases/physiopathology , Elasticity , Humans , Male , Middle Aged , Rest , Stroke Volume , Systole , Valsalva ManeuverABSTRACT
It has recently been suggested that mean arterial pressure provides a reliable estimate of dicrotic notch pressure in infants and children. The aim of the present study was twofold: (1) to investigate the relation existing between aortic dicrotic notch pressure and both the steady and pulsed component of aortic pressure in adults (i.e., mean and pulse aortic pressures, respectively); and (2) to evaluate mean aortic pressure as an estimate of aortic dicrotic notch pressure. High-fidelity pressure recordings were obtained at the aortic root level in 17 men (52 +/- 13 years). Pressure data were analyzed at rest over 10 consecutive beats in each patient, and, in 6 patients, during the Valsalva maneuver (over 22 to 50 consecutive beats). At rest, dicrotic notch pressure was greater than mean pressure (109.0 +/- 17.9 vs 99.6 +/- 12.5 mm Hg, p = 0.0001). Dicrotic notch pressure was positively related to mean pressure (r = 0.93) and to pulse pressure (r' = 0.77), but not to patient's heart rate, cardiac output, or total estimated arterial compliance. There was a spontaneous beat-to-beat relation between dicrotic notch and mean pressures (1) at rest in 16 of 17 patients (mean r = 0.85), and (2) in all patients undergoing the Valsalva maneuver (mean r = 0.97). During the maneuver, intravascular mean pressure ranged from 59 to 171 mm Hg. Dicrotic notch pressure was positively related to mean pressure (r = 0.98) and to pulse pressure (r' = 0.44). Both at rest and during the Valsalva maneuver, mean pressure underestimated dicrotic notch pressure, and the higher the dicrotic notch pressure, the more negative the percent error (each p = 0.0001). In conclusion, aortic dicrotic notch pressure was mainly related to the steady component of aortic pressure. The mean aortic pressure slightly but significantly underestimated aortic dicrotic notch pressure, and thus should be used with greater caution in adults than in young patients as an estimate of end-systolic pressure.
Subject(s)
Aorta/physiology , Blood Pressure , Adult , Aged , Blood Pressure Determination , Cardiac Catheterization , Cardiac Output , Humans , Male , Middle Aged , Prospective Studies , Valsalva ManeuverABSTRACT
Two groups of worksite employees (58 in a control, 53 in an experimental group) underwent three 90-min. educational sessions designed to increase participation in exercise. At the end of the third session, experimental subjects were asked to complete a structured statement of exercise intention which addressed the major barrier to exercise. Two weeks following the program, chi-squared analysis showed that the two groups were proportionately different in changes in frequency and intensity of exercise such that the experimental group in both cases showed greater changes than the control. Experimental subjects showed a twofold increase in frequency and intensity of exercise over the control group. Pearson r indicated a statistically significant association between the completeness of structured statements of intention and an increase in frequency of exercise. We conclude that structured statements of intention are useful for distinguishing between contrived barriers to exercise (excuses) and actual barriers that require practical solutions.
Subject(s)
Exercise/psychology , Health Education , Motivation , Workplace , Adult , Female , Health Knowledge, Attitudes, Practice , Health Promotion , Humans , Male , Middle AgedABSTRACT
OBJECTIVE: Determine the evolution of left ventricular ejection fraction during weaning. DESIGN: Prospective study. SETTING: Intensive care unit of a university teaching hospital. PATIENTS AND PARTICIPANTS: 12 consecutive mechanically ventilated patients, without documented coronary artery disease, suffering from acute exacerbation of chronic obstructive pulmonary disease and able to be weaned. MEASUREMENTS AND RESULTS: Left ventricular ejection fraction was determined during mechanical ventilation, inspiratory pressure support (10 cmH2O) and spontaneous ventilation with constant inspiratory oxygen fraction using technetium 99m radionuclide angiography. Spontaneous ventilation induced a significant decrease in left ventricular ejection fraction from 54.5 +/- 12.4 to 47.0 +/- 13% (p < 0.01). Inspiratory pressure support induced a slight but non-significant decrease in left ventricular ejection fraction from 55.0 +/- 12.1 to 50.3 +/- 12.4%. Left ventricular ejection fraction was homogeneously reduced by spontaneous ventilation without patent regional wall motion abnormalities of the left ventricle. Myocardial 201thallium imaging performed 15 min after weaning showed a normal perfusion in the left ventricle anterior and posterior free wall. CONCLUSION: Weaning of patients suffering from chronic obstructive pulmonary disease without coronary artery disease induced a significant reduction in left ventricular ejection fraction. The non significant decrease in left ventricular ejection fraction observed with inspiratory pressure support suggested that our results might be explained by a weaning induced increase in afterload.