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Biomedical subjects

P Pibarot

Publications and source records attributed to P Pibarot.

At least 37 records · Page 2Linked to original sources
PubMed1999

Comparison of ketoprofen and carprofen administered prior to orthopedic surgery for control of postoperative pain in dogs.

OBJECTIVE: To compare analgesic and adverse effects of ketoprofen and carprofen when used to control pain associated with elective orthopedic surgeries in dogs. DESIGN: Prospective randomized clinical trial. ANIMALS: 93 client-owned dogs: 46 undergoing reconstruction of the cranial cruciate ligament, 47 undergoing femoral head and neck excision, and 15 control dogs anesthetized for radiographic procedures. PROCEDURE: Dogs undergoing surgery were randomly given ketoprofen, carprofen, or saline (0.9% NaCl) solution, SC, prior to surgery. Pain score and serum cortisol concentration were recorded for 12 hours after surgery for all dogs. When pain score was > or = 7, oxymorphone was administered i.m. Bleeding time was measured prior to and during surgery. RESULTS: The proportion of dogs that required oxymorphone was significantly higher for the carprofen and placebo groups than for the ketoprofen group. Pain score for the placebo group was significantly higher than for the ketoprofen and carprofen groups, 2, 8, and 9 hours after surgery. Cortisol concentration was significantly higher for the placebo group than for the carprofen group at 4 and 6 hours after surgery. Significant differences were not detected between ketoprofen and carprofen groups with respect to pain score and cortisol concentration. Bleeding time was significantly longer for the ketoprofen group than for the other groups during surgery. One dog treated with ketoprofen developed a hematoma at the surgical site. CONCLUSIONS AND CLINICAL RELEVANCE: Ketoprofen and carprofen given prior to surgery were effective for postoperative pain relief in dogs. However, ketoprofen should not be used when noncompressible bleeding may be a problem.

Animals↗
PubMed1999

Usefulness of the indexed effective orifice area at rest in predicting an increase in gradient during maximum exercise in patients with a bioprosthesis in the aortic valve position.

This study examines the hemodynamic behavior of aortic bioprosthetic valves during maximum exercise. Nineteen patients with a normally functioning stented bioprosthetic valve and preserved left ventricular function were submitted to maximum ramp bicycle exercise. In 14 of the 19 patients, valve effective orifice area and mean gradient were measured at rest and during exercise using Doppler echocardiography. At peak exercise (mean maximal workload 118 +/- 53 W), the cardiac index increased by 122 +/- 34% (+3.18 +/- 0.71 L/min/ m2, p <0.001), whereas mean gradient increased by 94 +/- 49% (+12 +/- 8 mm Hg, p <0.001), and effective orifice area by 9 +/- 13% (+0.15 +/- 0.22 cm2, p = 0.02). A strong correlation was found between the increase in mean gradient during maximum exercise and the valve area at rest indexed for body surface area (r = 0.84, p <0.0001). Due to the increase in valve area, the increase in gradient was less (-9 +/- 7 mm Hg, -41 +/- 33%, p = 0.0006) than theoretically predicted assuming a fixed valve area. These results suggest that the effective orifice area of the bioprostheses has the capacity to increase during exercise; therefore, limiting the increase in gradient. The relation found between the indexed effective orifice area at rest and the increase in gradient during exercise should be useful in predicting the hemodynamic behavior of a stented bioprosthesis during exercise.

Aged↗
PubMed1999

Changes in left ventricular mass and function after aortic valve replacement: a comparison between stentless and stented bioprosthetic valves.

The objective of this study was to compare stentless bioprostheses with stented bioprostheses with regard to the postoperative changes in left ventricular (LV) mass and function. Forty patients with aortic stenosis undergoing valve replacement with a stentless (20 patients) or a stented (20 patients) bioprosthesis were evaluated early (baseline), 1 year, and 2 years after operation. Left ventricular mass index was calculated with the corrected American Society of Echocardiography formula. The relative changes between end-diastole and end-systole in LV mid-wall radius, length, and volume (ejection fraction) were determined with a previously validated model for dynamic geometry of the left ventricle. Overall, a significant decrease was found in LV mass index (from 155 +/- 30 to 112 +/- 23 g/m(2); P <.001) and a significant increase in longitudinal shortening (from 0.12 +/- 0.11 to 0.22 +/- 0.08; P <. 001), and ejection fractions (from 0.67 +/- 0.11 to 0.71 +/- 0.10; P =.017). No significant change was found in the mid-wall radius shortening fraction. Two years after surgery, the extent of LV mass regression was greater in stentless bioprostheses (-51 +/- 18 vs -35 +/- 17 g/m(2); P =.01), though the average mass index was similar in both groups (114 +/- 26 vs 110 +/- 20 g/m(2)). Also at 2 years, the longitudinal shortening fraction was greater in patients with a stentless bioprosthesis (0.25 +/- 0.07 vs 0.18 +/- 0.08; P =.03). In conclusion, this study suggests that the superior hemodynamic performance of stentless bioprostheses may have some benefits with regard to LV mass regression and function after aortic valve replacement. The significance of these benefits in terms of prognosis remains to be determined.

Aged↗
PubMed1999

A new flow model for Doppler ultrasound study of prosthetic heart valves.

BACKGROUND AND AIM OF THE STUDY: Steady and pulsatile flow models used to assess the hydrodynamic aspects of prosthetic heart valves are generally made of Plexiglas and Lucite tubing. They often allow continuous-wave and pulsed-wave Doppler ultrasound velocity measurements to be made parallel to the flow, but cannot be used as such for ultrasound scanning of valve inflow and outflow velocities because of ultrasonic reverberation and refraction by the tubing. The aim of the study was to develop a new flow model which allowed ultrasonic scanning of the prosthetic valve flow for three-dimensional (3D) reconstruction of color Doppler flow distributions. METHODS: The flow model, designed with left ventricular and aortic chambers composed of agar gel which mimics the ultrasound characteristics of biological tissues, was developed and tested for comparative in vitro hydrodynamic and Doppler ultrasonic studies of aortic prosthetic valves. An electromagnetic flowmeter and a pressure monitor provided the flow and pressure signals for the hydrodynamic tests. The Doppler ultrasonic evaluation was performed with an Ultramark 9 HDI ultrasound system and a 3D ultrasound imaging system. The model was designed to enable assessment of prosthetic valve performance by pulsed-wave and continuous-wave Doppler velocity measurements, as well as by 3D color Doppler velocity measurements obtained by ultrasonic scanning of the left ventricle or aortic chamber with an ultrasound probe mounted on a motorized translation assembly. RESULTS: The study results showed that this new flow model can provide 3D color Doppler velocity distributions as well as accurate comparisons of hydrodynamic parameters of mechanical and bioprosthetic heart valves derived from Doppler and catheter measurements, both under steady and pulsatile flow conditions. CONCLUSION: This new flow model can be used to evaluate the usefulness of hydrodynamic parameters for the assessment of prosthetic heart valves using both conventional Doppler echocardiography, as currently used in patients, and 3D color Doppler ultrasonic imaging.

Blood Flow Velocity↗
PubMed1999

Midterm follow-up of unstented biological valves.

We have used the stentless aortic biosprosthesis for aortic valve replacement during the last 10 years. Since 1988, 647 stentless aortic prosthesis were implanted: 384 unstented heterografts, 176 Ross procedures, and 87 homografts. Patients up to age 50 were offered the Ross procedure, those between the ages of 50 and 60 a homograft, and patients 60 years old and older received heterografts. All patients were evaluated at our clinic. An echocardiogram was obtained before discharge from the hospital, at 3 to 6 months postoperatively, and yearly thereafter. Gradients, regurgitation, and effective orifice area were recorded at each visit. The patient was also evaluated clinically. Early mortality rate was 5.4%, 1.7%, and 5.8% for heterograft, autograft, and homograft, respectively. The mean gradient for the unstented porcine valve was 7.6 mm Hg at 3 to 6 month but 5 mm Hg or less for the homografts or autografts. Unstented valves are relatively new but they showed superior hemodynamic performance compared with either mechanical or biological stented valves. Anticoagulation is not mandatory, which should decrease the number of complications. They are the replacement of choice for young and old patients with a small aortic root and are the best alternative to the natural valve.

Adult↗
PubMed1998

Application of the matching pursuit method for structural decomposition and averaging of phonocardiographic signals.

The paper evaluates the performance of an automatic adaptive time-frequency method to detect each cardiac cycle of a phonocardiogram (PCG) and extract average heart sounds and PCG cycles. The proposed method combines a global search of the PCG, in terms of the energy distribution of the most important components, with a local search relating to the specific events found within a cardiac cycle. The method is applied to 100 PCG recordings from 50 patients with an aortic bioprosthetic valve. The performance of the proposed method is compared with a commonly used semi-automatic method that is based on the combined analysis of an electrocardiogram (ECG) and the PCG signal. Results show that the proposed method clearly outperforms the semi-automatic method, especially in the case of patients with malfunctioning bioprostheses. By eliminating the need to record an ECG as the time-reference signal, this method reduces hardware overheads when analysis of PCG signals is the primary aim. It is also independent of subjective human judgment for selection of reference templates and threshold levels. Furthermore, the method is robust to artefacts, background noise and other kinds of signal interferences. With minor modifications, the procedure described could be applied to other types of biomedical signal in order to extract coherent transient components and identify specific events.

Aortic Valve↗
PubMed1998

Impact of prosthesis-patient mismatch on hemodynamic and symptomatic status, morbidity and mortality after aortic valve replacement with a bioprosthetic heart valve.

BACKGROUND AND AIMS OF THE STUDY: Previous studies have shown that the effective orifice area of an aortic prosthetic valve may be too small in relation to the patient's body surface area, resulting in abnormally high gradients. The consequences of this condition, termed prosthesis-patient mismatch, have not been fully studied. The study objective was to determine if the condition has a detrimental effect on symptomatic and hemodynamic status, morbidity and mortality of patients undergoing aortic valve replacement. METHODS: A cohort of 392 patients was prospectively followed for up to seven years after implantation of a Medtronic Intact bioprosthesis. Doppler echocardiography was performed annually in 72 patients. Based on previous studies, presence of mismatch was defined as an indexed valve area < or = 0.85 cm2/m2. RESULTS: Mismatch was associated with less postoperative improvement of NYHA functional class (p < 0.009) independently of other predictors, such as age and preoperative functional class, but had no significant impact on patient survival (mismatch: 75 +/- 4%, no mismatch: 79 +/- 3%; p = 0.59) and valve-related morbidity up to seven years. Cardiac index was similar in patients with and without mismatch up to three years after operation but decreased significantly thereafter only in patients with mismatch (-0.54 +/- 0.32 versus -0.17 +/- 0.49 l/min/m2; p = 0.04). Likewise, the mean transprosthetic gradient, which was higher at one year after operation in patients with mismatch (22 +/- 8 versus 15 +/- 7 mmHg), increased significantly (+6 +/- 6 versus +1 +/- 1 mmHg; p = 0.008) only in this group during follow up. CONCLUSIONS: Patients with mismatch have less symptomatic improvement and worse hemodynamics that continue to deteriorate with time. However, medium-term prognosis (up to seven years) is relatively good. Further studies are necessary to determine the longer-term effects of mismatch on morbidity and mortality.

Aged↗
PubMed1997

Comparison of ketoprofen, oxymorphone hydrochloride, and butorphanol in the treatment of postoperative pain in dogs.

OBJECTIVE: To compare analgesic effects of ketoprofen, oxymorphone hydrochloride, and butorphanol when used to control postoperative pain associated with elective orthopedic surgery in dogs. DESIGN: Prospective randomized clinical trial. ANIMALS: 70 dogs undergoing orthopedic surgery on a hind limb. PROCEDURE: Dogs were randomly assigned to 1 of 4 postoperative analgesic treatment groups: ketoprofen alone, oxymorphone alone, butorphanol alone, or ketoprofen-oxymorphone. Drugs were given IM at the end of anesthesia. Pain score, sedation score, arterial blood pressures, arterial blood gas partial pressures, and plasma cortisol concentration were measured for 12 hours after surgery. If the pain score was > or = 9, supplemental oxymorphone was administered IM. RESULTS: The proportion of dogs that did not require supplemental treatment with oxymorphone was significantly higher for the ketoprofen alone and ketoprofen-oxymorphone groups than for the oxymorphone alone group. During the first hour after surgery, pain score was lower for oxymorphone alone and ketoprofen-oxymorphone groups than for ketoprofen or butorphanol alone groups. Significant differences were not detected among groups in regard to pain score 2 and 3 hours after surgery or in regard to arterial blood pressures at any time. From 4 to 12 hours after surgery, pain score was significantly lower for the ketoprofen alone group than for other groups. Plasma cortisol concentration was significantly higher for the oxymorphone alone group 6 and 8 hours after surgery, compared with other groups. CLINICAL IMPLICATIONS: Except during the first hour after surgery, dogs given ketoprofen alone after elective orthopedic surgery had a greater level of, and longer-lasting, analgesia than did dogs given oxymorphone or butorphanol alone.

Analgesics, Opioid↗
PubMed1997

Time-frequency analysis of heart murmurs. Part I: Parametric modelling and numerical simulations.

The object of this study is to compare the performance of two new bilinear time-frequency representation techniques with the spectrogram to characterise the behaviour of heart murmurs produced by bioprosthetic heart valves implanted in the mitral or aortic position. The murmurs are those of mitral stenosis, mitral regurgitation, aortic stenosis, aortic regurgitation, a diastolic musical murmur and a systolic musical murmur. In the first part of the study, the general characteristics of the amplitude and the spectral content of these murmurs are determined by visual observation of the spectrogram of phonocardiograms obtained from several patients with known valvular pathology complemented with a literature review. A parametric model is then generated for each murmur signal. Stenotic and regurgitant murmurs are modelled as the sequential output of a bank of low-pass filters excited by a white noise input signal. The basic parameters of each filter are selected to simulate, as a function of time, the basic characteristics of random heart murmurs. Musical murmurs are modelled as a frequency-modulated deterministic sinusoid of constant amplitude. Numerical simulations of these random and musical heart murmurs are then generated and will be used in Part II to determine the best of three time-frequency representation techniques for analysing heart murmur signals.

Aortic Valve↗
PubMed1997

Catheter-assisted totally thoracoscopic coronary artery bypass grafting: a feasibility study.

BACKGROUND: The purpose of this study is to examine the feasibility of performing totally thoracoscopic internal mammary-to-coronary artery bypass grafting with the assistance of radiologically guided catheter intervention. METHODS: Fourteen dogs were subjected to mobilization of the internal mammary artery and anastomosis of it to the left anterior descending coronary artery over an angiographic catheter inserted into the internal mammary artery under fluoroscopy. The anastomosis was completed over the catheter using sutures and the application of fibrin glue. Eight animals underwent the anastomosis after their sacrifice. The other 6 animals were put on closed chest cardiopulmonary bypass and had their anastomosis done after intraaortic balloon occlusion and cardioplegic arrest of the heart. All animals had an angiographic and pathologic examination at the completion of the anastomosis. RESULTS: Anastomosis was completed in all dogs. Three anastomoses leaked and two were noted to be stenosed at completion of the anastomosis. One leak was sealed by application of fibrin glue. Both stenotic anastomoses were caused by suturing of the back wall when a short angiographic catheter could not be positioned across the anastomosis. CONCLUSIONS: Minimally invasive totally thoracoscopic mammary-to-coronary artery bypass grafting with catheter assistance is feasible. Technical improvement and appropriate instrumentation are required to minimize anastomotic failure.

Animals↗
PubMed1996

Estimation of pulmonary artery pressure by spectral analysis of the second heart sound.

The objective of the present work was to test and validate a noninvasive method based on spectral analysis of the second heart sound (S2) to estimate the pulmonary artery (PA) systolic pressure in 89 patients with a bioprosthetic heart valve. The technique was compared with continuous-wave Doppler estimation of PA systolic pressure in these patients. The heart sounds recorded at the pulmonary area on the chest wall were digitized by computer. The spectra of S2 and those of the aortic (A2) and the pulmonary (P2) components of S2 were computed with a fast-Fourier transform. Seven features were extracted from these spectra. The statistical analysis performed with the Pearson linear correlation coefficient showed that the best estimation of PA systolic pressure obtained by spectral phonocardiography (r = 0.84, SEE +/- 5.6 mm Hg, p <0.0001) was provided by the following equation: PA systolic pressure = 47 + 0.68 Fp - 4.4 Qp - 17 Fp/Fa - 0.15 Fs, where Fs and Fp are dominant frequencies associated with the maximal amplitude of the power spectra of S2 and P2, respectively, Qp is the quality of resonance of P2, and Fp/Fa is the ratio of the dominant frequencies of P2 and A2, respectively.

Adult↗
PubMed1996

The effect of prosthesis-patient mismatch on aortic bioprosthetic valve hemodynamic performance and patient clinical status.

BACKGROUND: High pressure gradients occurring through normally functioning prosthetic valves appear to be related to a mismatch between the effective orifice area of the prosthesis and the patient's body surface area. OBJECTIVE: To determine whether prosthesis-patient mismatch affects clinical and hemodynamic status, a group of patients with a bioprosthetic heart valve in the aortic position was prospectively evaluated at 6.2+/-4.4 years after implantation by transthoracic Doppler echocardiography. METHODS: Manufacturer-derived in vitro valve areas were available in 61 patients allowing classification into two subgroups, with or without mismatch, based on a valve area at implantation indexed for body surface area 0.85 cm2/m2 or less, or greater than 0.85 cm2/m2. Clinical and hemodynamic parameters evaluated at follow-up included New York Heart Association (NYHA) class distribution, mean transprosthetic gradient, prosthetic valve area and cardiac index. RESULTS: Prosthesis-patient mismatch was present in 32 of 61 patients (52%). Although NYHA class of the patients was similar in both groups, hemo-dynamic performance of the aortic bioprostheses was worse in patients with mismatch than in patients with no mismatch, as indicated by a higher mean gradient (22+/-9 versus 15+/-8 mm Hg, P=0.002) and a lower cardiac index (3.0+/-0.7 versus 3.4+/-0.7 L/min/m2, P=0.04). The prevalence and severity of intrinsic prosthetic dysfunction were similar in both groups. Despite similar NYHA functional class distribution in both groups, the occurrence of syncope, acute pulmonary edema and angina pectoris was significantly higher in patients with mismatch (50% versus 21%, P=0.017). CONCLUSIONS: Prosthesis-patient mismatch is associated with worse hemodynamic performance and higher prevalence of adverse clinical events. However, mismatch did not promote accelerated hemodynamic or structural deterioration of the bioprosthesis.

Angina Pectoris↗
PubMed1995

Digital signal processing of the phonocardiogram: review of the most recent advancements.

The objective of the present paper is to provide a detailed review of the most recent developments in instrumentation and signal processing of digital phonocardiography and heart auscultation. After a short introduction, the paper presents a brief history of heart auscultation and phonocardiography, which is followed by a summary of the basic theories and controversies regarding the genesis of the heart sounds. The application of spectral analysis and the potential of new time-frequency representations and cardiac acoustic mapping to resolve the controversies and better understand the genesis and transmission of heart sounds and murmurs within the heart-thorax acoustic system are reviewed. The most recent developments in the application of linear predictive coding, spectral analysis, time-frequency representation techniques, and pattern recognition for the detection and follow-up of native and prosthetic valve degeneration and dysfunction are also presented in detail. New areas of research and clinical applications and areas of potential future developments are then highlighted. The final section is a discussion about a multidegree of freedom theory on the origin of the heart sounds and murmurs, which is completed by the authors' conclusion.

Coronary Disease↗
PubMed1995

Cardiorespiratory effects of hemic versus nonhemic prime during and immediately following mitral valve replacement in dogs.

In order to limit the hemodilution effect during cardiopulmonary bypass (CPB) in low weight animal patients, blood is often used as a component of the prime solution. This study was undertaken to evaluate the effects of the addition of blood to the prime solution on the hemodynamic and respiratory parameters during and following mitral valve replacement in dogs. Ten dogs were randomly assigned to receive either a hemic (HP), 75% blood component, or a nonhemic prime (NP) solution. The hemodilution was 5 +/- 4% and 25 +/- 10% for the HP and NP groups, respectively. Cardiopulmonary measurements were taken 20 minutes before initiating CPB, during CPB, and 20 min after termination. The hematocrit level, the hemoglobin concentration, and the arterial oxygen content were significantly lower in the NP group during and following CPB. However, the systemic oxygen transport index was not significantly different between the NP group (355 +/- 87 mL/min/m2) and the HP group (546 +/- 155 mL/min/m2) following CPB. Our study indicates that, in normal dogs undergoing hemodilution from a nonhemic prime solution, the cardiovascular function is able to maintain the systemic oxygen transport in the period immediately following mitral valve replacement.

Analysis of Variance↗
PubMed1992

Optimal time-window duration for computing time/frequency representations of normal phonocardiograms in dogs.

The optimal duration of the time-window used to compute the time-frequency representation (spectrogram) of the phonocardiogram was studied in four dogs by using intracardiac and thoracic measurements of the PCG. The power and cross-spectrograms of the intracardiac and thoracic PCGs were computed using a fast Fourier transform algorithm and a sine-cosine window with 10 per cent decaying functions. A coherence spectrogram was also computed for each dog to study the linear relationship between the two signals and determine the optimal time-window duration. Results show that the optimal range of the time-window duration is between 16 and 32 ms. A time-window shorter than 16 ms spreads out low-frequency components into the higher frequencies and generates a spectrographic representation with poor frequency resolution (> or = 62.5 Hz). A window larger than 32 ms increases the frequency resolution but smears the spectrographic representation of the signal in the time domain and thus cannot correctly reflect the time-varying properties of the signal. In both cases, the amplitude of the coherence function computed between the left ventricular and the thoracic phonocardiograms is overestimated.

Animals↗