PubMed Health⌕ Search

Biomedical subjects

P Havlik

Publications and source records attributed to P Havlik.

At least 19 recordsLinked to original sources
PubMed2001

Chronic heart failure in the community: missed diagnosis and missed opportunities.

BACKGROUND: The aim of this study was to determine the incidence of congestive heart failure (CHF) in patients discharged from a hospital without a diagnosis of CHF who were admitted with shortness of breath and had a low left ventricular ejection fraction (LVEF). CHF is a devastating disease in terms of financial cost, prevalence, and effect on morbidity and mortality. The true incidence rate is not known because of reliance on discharge records and death certificates, and because diagnosis remains a clinical judgment. METHODS AND RESULTS: CHF was diagnosed by the Framingham criteria. We retrospectively reviewed the records of 225 randomly selected patients admitted with a complaint of shortness of breath and discharged without a diagnosis of CHF (group 1). We compared group 1 with patients admitted at the same time with a diagnosis of CHF and of similar age and LVEF (group 2). In group 1, 100 patients had a low LVEF (< or =40%) and 51% met criteria for CHF that had been missed. Readmission rate was high (42%). Mortality at 12 months was 18%. Rate of cardiomegaly on x-ray films was similar in groups 1 and 2 (64.6% v 64.4%, respectively). Third heart sound (39% v 10%; P <.001) and heart rate > 120 beats/min (41.7% v 12.5%; P <.001) were significantly more frequent in group 1. By contrast, signs and symptoms suggestive of fluid overload were more frequent in group 2. CONCLUSIONS: Many patients admitted with shortness of breath and low LVEF have CHF but are not diagnosed. Physicians are more likely to miss CHF in patients presenting without signs of fluid overload even when third heart sound is present with resting tachycardia. A missed diagnosis of CHF is associated with a high readmission rate, multiple admissions, and a mortality rate comparable to that of patients with newly diagnosed CHF.

Aged↗
PubMed2001

Myocardial infarction in young adults with low-density lipoprotein cholesterol levels < or = 100 mg/dL: clinical profile and 1-year outcomes.

STUDY OBJECTIVES: To define the clinical profile of young adults with optimal low-density lipoprotein (LDL) cholesterol levels who present with acute myocardial infarctions (MIs); to compare and contrast differences in the clinical profiles of young adults admitted to the hospital with MIs who have LDL cholesterol levels < or = 100 mg/dL and those with LDL cholesterol values > or = 160 mg/dL; and to evaluate the clinical outcomes for the two groups at 1 year. DESIGN: A retrospective chart review was conducted on all young men (55 years) and women (65 years) admitted to the hospital for MIs within a 2-year period (n = 232). A history of cardiovascular risk factors and 1-year outcomes were obtained. SETTING: Rural community medical center serving a tri-state area in the midwestern United States. PATIENTS: Patients were included in this analysis if (1) a lipid profile was drawn within 24 h of hospital admission and (2) the patient was not receiving a statin medication on hospital admission. MEASUREMENTS AND RESULTS: Of the 183 patients who met the inclusion criteria, as many as 68% (124 patients) had LDL cholesterol levels of < or = 130 mg/dL, 29% (53 patients) had LDL cholesterol level of < or = 100 mg/dL, and only 14% (26 patients) had LDL cholesterol levels of > or = 160 mg/dL. Patients were categorized into group 1 if their LDL cholesterol level was < or = 100 mg/dL and were categorized into group 2 if their LDL cholesterol level was > or = 160 mg/dL. In group 2, 92% of patients were placed on a statin medication. By 1 year, the mean LDL cholesterol level had decreased from 188 to 106 mg/dL. The rate of coronary artery bypass graft and percutaneous coronary intervention procedures was similar between groups. Hospital readmission rates (43.4% vs 50%, respectively) and 1-year mortality rates (9% vs 8%, respectively) were not different between groups group 1 and 2. CONCLUSIONS: Young adults experiencing acute MIs typically have acceptable cholesterol levels (ie, < or = 130 mg/dL) or optimal values (ie, < or = 100 mg/dL). In those patients with abnormal cholesterol levels, a combined strategy of aggressive intervention and adherence to secondary prevention protocols including lipid control is successful in improving outcomes.

Adult↗
PubMed1999

Decrease of subcutaneous adipose tissue lipolysis after exposure to hypoxia during a simulated ascent of Mt Everest.

The purpose of this study was to examine the effects of prolonged hypoxia on adipose tissue lipolysis, in relation to the weight loss usually observed at high altitude. Eight male subjects were exposed for 31 days to gradually increasing hypobaric hypoxia up to the equivalent altitude of 8848 m (Mt Everest) in a decompression chamber, after 7 days at 4350 m for altitude pre-acclimatization. A biopsy of subcutaneous adipose tissue was performed before and after hypoxic exposure, to study in vitro changes in adipose tissue sensitivity. Fat mass, adipocyte volume and spontaneous lipolysis were not impaired by the exposure to hypoxia. The in vitro lipolytic response to epinephrine, isoproterenol, growth hormone (GH) and parathormone (PTH) decreased significantly (P<0.01, P<0.05, P<0.01 and P<0.01 respectively), as did the plasma concentration of free fatty acid (P<0.01). The anti-lipolytic effect promoted by alpha2-adrenergic receptor stimulation (epinephrine with propranolol) was greater after hypoxia (P<0.05), while the anti-lipolytic activity of insulin was decreased (P<0.01). In conclusion, prolonged exposure to hypobaric hypoxia led to a potent reduction in lipid mobilization, through a decrease in the efficiency of beta-adrenergic, GH and PTH lipolytic pathways, as well as an increment in the alpha2-adrenergic-receptor-mediated anti-lipolytic effects.

Adipose Tissue↗
PubMed1998

Study of left ventricular bypass using Wankel type semipulsatile blood pump.

The influence of the Wankel type semipulsatile left ventricular assistance on hemodynamics was investigated with a computer simulation and an animal experiment. A simulation circuit was constructed to express the circulatory system. A current source was added to create a semipulsatile blood pump. The left and right ventricles were replaced by variable compliances. Left heart failure was simulated by decreasing the amount of compliance change of the left ventricle. Under the condition of heart failure when semipulsatile assist flow increased, the mean aortic pressure (AoP), tension time index (TTI), and diastolic pressure time index (DPTI) increased, and the cardiac output, pulse pressure (PP), and pulsatility indicator (PI) decreased. In an animal experiment, a Wankel type blood pump was used in a calf. With the increase of the assist flow, AoP curves became less pulsatile, and PP and PI decreased in accordance, which was predicted by the numerical simulation.

Animals↗
PubMed1997

Physico-chemistry and cytotoxicity of ceramics: part I: characterization of ceramic powders.

The morphology of Al2O3, ZrO2/Y2O3, AIN, B4C, BN, SiC, Si3N4, TiB2, TiC, TiN ceramic, graphite and diamond powders has been studied by scanning electron microscopy (SEM) and the specific area of each powder was determined with the BET method. X-ray diffraction (XRD) investigations have been carried out in order to evaluate the crystallinity and determine the constitutive phases. The chemical composition was assessed by classical chemical analyses and by X-ray microprobe; some powders were studied by the laser micro-Raman technique. Correlations have been established between all these results.

Journal Article↗
PubMed1997

Cora rotary pump for implantable left ventricular assist device: biomaterial aspects.

Our group is developing a left ventricular assist device based on the principle of the Maillard-Wankel rotative compressor: it is a rotary, not centrifugal, pump that produces a pulsatile flow. Stringent requirements have been defined for construction materials. They must be light, yet sufficiently hard and rigid, and able to be machined with high precision. The friction coefficient must be low and the wear resistance high. The materials must be chemically inert and not deformable. Also, the materials must be biocompatible, and the blood contacting surface must be hemocompatible. We assessed the materials in terms of physiochemistry, mechanics, and tribology to select the best for hemocompatibility (determined by studies of protein adsorption; platelet, leukocyte, and red cell retention; and hemolysis, among other measurements) and biocompatibility (determined by measurement of complement activation and toxicity, among other criteria). Of the materials tested, for short- and middle-term assistance, we chose titanium alloy (Ti6Al4V) and alumina ceramic (Al2O3) and for long-term and permanent use, composite materials (TiN coating on graphite). We saw that the polishing process of the substrate must be improved. For the future, the best coating material would be diamond-like carbon (DLC) or crystalline diamond coating.

Adsorption↗
PubMed1996

Biological evaluation of mechanical circulatory support systems in calves.

Data from animal experiments with mechanical circulatory support systems (MCSS) performed in Groningen and Marseille over the past years were used to obtain normal values of hematological, coagulation, rheological and blood chemistry parameters in calves. These parameters were divided between two groups: a limited number of parameters necessary to assess biocompatibility properties of MCSS quickly and a more extensive number of parameters suitable for more detailed biological evaluation of blood pumps. All applied tests can be examined in calf blood as well as in human blood. Parameters were selected on clinical relevance and usefulness for standardization procedures. The obtained data were compared with normal values in human beings derived from the literature.

Animals↗
PubMed1995

Experimental use of a semipulsatile rotary blood pump for cardiopulmonary bypass.

We tested our valveless pulsatile rotary blood pump (CORA) extensively in animals, but only as a temporary implantable left ventricular assist device. To expand the scope of future clinical applications, we recently undertook experiments to assess the feasibility of our pump for use in a standard cardiopulmonary bypass circuit. We conducted 4 experiments in adult sheep (body weight, 40 kg): 2 with CORA and 2 with the BioMedicus pump (BP) for comparison. In all experiments, a currently used extracorporeal circuit with reservoir, filter, and membrane oxygenator (Sorin monolith) was installed, and open chest extracorporeal circulation (ECC) was performed for 6 h. Hemodynamic performance and hemolysis were evaluated. CORA provided semipulsatile systemic flow at a level comparable to that of the BP. Free plasma hemoglobin levels were slightly higher with CORA, but the decrease in platelet count was the same for both devices. There was no significant difference in the extent of blood trauma. We conclude that CORA could be successfully used for ECC with an oxygenator. Negative pressure can be prevented by our specially designed control system.

Animals↗
PubMed1994

Development of the Marseilles pulsatile rotary blood pump for permanent implantable left ventricular assistance.

We have developed a low-speed, double-lobed hypocycloidal pump that furnishes a pulsatile flow without valves. The pump is coupled to a specially designed electric motor. The motor/pump unit is totally implantable and has been extensively tested in vitro and in vivo in animals. Because this pump is volumetric, it is necessary to control speed precisely to avoid overpumping. Our control system, which is based on analysis of the motor current wave form, can detect and prevent negative pressures before they occur. The physical properties and hemocompatibility of several construction materials have been studied to determine their suitability for clinical use. These materials include a graphite substrate, titanium nitrate surface coating, boric carbon, and amorphous diamond. The pumps currently being tested are made of titanium, but clinical versions will be made of composite materials selected from this preliminary study. In vivo testing of this pump confirmed its good hemodynamic performance, low hemolysis rate, and biocompatibility (i.e., low heat, noise, and vibration levels). Animal experiments were terminated after 15 days because of mechanical failure related to the accumulation of blood components on moving parts. A new pump in which the mechanism is completely sealed from the blood flow has been designed and will soon be tested. If this sealed design is effective, the pump should be ready for use as a permanent implantable ventricular assistance device.

Animals↗
PubMed1994

[Evaluation of vertebral bone mass in anorexia nervosa].

Lumbar bone mineral content (BMC) of 33 female patients aged 14-30 years (19 +/- 4.1 (mean +/- SD) with anorexia nervosa (duration 31 +/- 37 months) was studied using dual X-ray absorptiometry. Results were compared with the data obtained in a population of 26 women aged 17-38 years without bone disease. BMC was significantly decreased (0.872 +/- 0.107 g/cm2 hydroxyapatite) in anorectic patients as compared to controls (1.008 +/- 0.098 hydroxyapatite). A single patient had a non traumatic vertebral compression fracture. A statistically significant negative correlation was found between BMC and duration of amenorrhea (r = 0.48; p < 0.01). There was no significant correlation between BMC and body mass index or daily calorie intake. Ovarian steroid deficiency might thus be a major factor--among other ones--in the development and the degree of bone loss in anorexia nervosa.

Absorptiometry, Photon↗
PubMed1993

TiN coating: surface characterization and haemocompatibility.

The left ventricular assist device under consideration is based on the principle of the Maillard-Wankel rotary pump. The construction materials must meet stringent requirements. Titanium nitride was chosen for its surface properties and graphite for its bulk characteristics. The purpose of this study was to characterize the chemical vapour deposition titanium nitride coating via morphology, roughness, crystallinity, chemical composition, to report and discuss the results of in vitro haemocompatibility tests (protein adsorption, platelet retention, haemolysis) and to discuss physico-chemical and biological results. This chemical vapour deposition titanium nitride coating is well tolerated by the blood despite its surface irregularities, and appears as a good candidate material after improvements.

Absorption↗
PubMed1993

Blood haemolysis by ceramics.

Ceramics are more and more frequently under consideration for construction of blood-contacting devices, i.e. cardiac valves or cardiac assist devices. This study evaluated the haemolysis eventually initiated in vitro by ceramic powders (Al2O3, ZrO2/Y2O3, AlN, B4C, BN, SiC, Si3 N4, TiB2, TiN, TiC), graphite and diamond. The chemical composition of the powders was studied by X-ray microprobe and various other methods, and BET specific areas were determined. The haemolysis was almost zero for all powders, except AlN which showed slight haemolysis and TiB2 which had high haemolytic power.

Aluminum↗
PubMed1993

Haemocompatibility of Ti6A14V alloy.

Ti6A14V alloy has been mainly used as a biomaterial in the orthopaedic field. The present study describes the surface state of the Ti6A14V material and evaluates its in vitro haemocompatibility in terms of protein adsorption, platelet retention and haemolysis. The behaviour of the Ti6A14V alloy towards albumin and fibrinogen was compared to that of a reference medical-grade elastomer. The platelet retention test gave better results than those achieved with the elastomer. The haemolysis percentage of the alloy was almost zero. These results indicate that the Ti6A14V alloy is well tolerated by blood.

Adsorption↗
PubMed1993

A new model to test platelet adhesion under dynamic conditions. Application to the evaluation of a titanium nitride coating.

In order to evaluate under dynamic circumstances the in vitro platelet adhesion induced by rigid materials such as ceramic coatings deposited on selected substrates, a new model simulating a tube has been designed. In vitro platelet adhesion was assessed with this new model: the material was titanium nitride (TiN) deposited on Ti6A14V (TA6V) titanium alloy by a physical vapor deposition (PVD) process. The results were compared to those obtained with complete titanium carbide (TiC) graphite tubes coated with TiN by a chemical vapor deposition (CVD) process. The difference observed (less than 25%) in favour of the new system, could be due to the better surface state of the construction materials of this system. In fact it is a systemic error. However TiN confirms its good performance as a blood-contacting biomaterial.

Alloys↗
PubMed1989

[Clinical history and anatomic findings following the longest survival after cardiac transplantation].

The authors report the case history of the first patient in the world to have survived 18 and a half years with a heart transplant. This survival was marked by several episodes of rejection during the early years and various other incidents. The pathology encountered was primarily iatrogenic: diffuse osteoporosis sometimes limited the patient's activity. Two skin cancers and a lung cancer were diagnosed and treated. The patient died from progressive respiratory failure with pulmonary hypertension and signs of right ventricular failure. Pathological examination revealed a subnormal myocardium with a certain amount of overloading of the coronary arteries, confirmed the lung cancer and pulmonary hypertension and, most importantly, revealed the presence of nodular regenerative hepatic cirrhosis responsible for ascites during the last few months of life and a renal adenocarcinoma. These last two lesions are observed in immunosuppressed patients. The authors pay tribute to this patient who led an active and devoted life in the service of others.

Carcinoma, Bronchogenic↗
PubMed1988

[18 and one-half years' survival after cardiac graft. Clinical course and anatomical findings].

Operated upon in November, 1968, the last survivor of heart transplant recipients in those times has died on May 11, 1987, having survived 18 years and 6 months. The active life of this patient, however, was marred by episodes of graft rejection during the first post-operative years and by various incidents. It was mainly the complications of the immunosuppressive treatment that hampered his activities (osteoporosis) and provoked his death. Post-mortem examination confirmed that the heart was in good condition, found an active bronchial epithelioma and revealed iatrogenic lesions, namely adenomas, adenocarcinoma of the kidney and "regenerative" nodular hyperplasia of the liver with portal hypertension. Such lesions are observed in patients under long-term treatment with immunosuppressants. A "sleep apnoea" syndrome might have accounted for the formation of pulmonary hypertension lesions. The authors wish to pay their respects to this man who devoted himself to the service of other men.

Endomyocardial Fibrosis↗
PubMed1976

[The curve of the intraventricular pressure-volume relationships is not mono-exponential].

The graphic and statistic investigations have let us to assert that the right ventricular P/V relationship's curve is characterized by two successive segments: linear and exponential respectively. We have proposed an interpretation based on Roach's and Burton's works. Interest of information about this curve is double: 1) it is a function of the ventricular cavity volume; 2) it gives a general idea about the mode of ventricular filling.

Cardiac Volume↗