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Biomedical subjects

T Mesana

Publications and source records attributed to T Mesana.

At least 19 recordsLinked to original sources
PubMed1997

Aortic valve or root replacement with cryopreserved homograft for active infectious endocarditis.

Active aortic endocarditis is a serious condition that carries a high mortality and morbidity. The aim of this study was to analyse results obtained from 24 patients who underwent aortic valve or root replacement with cryopreserved homograft for aortic endocarditis. Eleven patients had native valve endocarditis, and 13 had prosthetic valve endocarditis. The mean age was 47.7 years: there were seven women and 17 men. Causative organisms were staphylococci (12), streptococci (four), serratia (one), candida (one), pneumococci (one), while no organisms were isolated in the remaining five patients. Complete reconstruction of the aortic annulus with homograft conduits was necessary in 20 patients (six total root and 14 mini-root). Infracoronary homograft aortic valve replacement was performed in the remaining patients. One patient died 1 day after the operation from ventricular failure, and two others died after 4 and 6 months as a result of arrhythmia. One patient died of recurrent endocarditis 1 year after surgery. The actuarial survival rate at 3 years was 83.4%. All survivors are symptom-free, with no evidence of recurrent endocarditis. Doppler echocardiography showed minimal aortic regurgitation in four patients.

Adult↗
PubMed1996

Value of Doppler echocardiography in the detection of low-grade rejections after cardiac transplantation.

Modifications of the diastolic parameters pressure half-time (PHT) and isovolumic relaxation time (IVRT), recorded using cardiac Doppler echocardiography (CDE), were studied in 23 heart transplant recipients and compared to the results of 345 endomyocardial biopsies (EMB) performed on the same day. Two different protocols, analyzing respectively (1) a decrease of 20% or more in IVRT and/or PHT with respect to the mean and (2) a decrease of 20% or more in IVRT and/ or PHT with respect to its preceding value, were used to evaluate the efficiency of CDE in diagnosing mild and moderate rejections. When a mild rejection was detected by EMB, a statistically significant decrease was found in the average CDE parameter values of the patient population. However, these variations were weak and did not differ from the spontaneous variations observed in each patient in the absence of rejection. Thus, it is not surprising that the sensitivity of CDE in the detection of mild rejections was very low (45%) using the most sensitive protocol (variations of the parameters from their preceding value). We conclude that CDE alone does not seem to be sufficient to perform the noninvasive diagnosis of low-grade rejections and must be complemented by other noninvasive methods.

Adult↗
PubMed1996

Cora valveless pulsatile rotary pump: new design and control.

For decades, research for developing a totally implantable artificial ventricle has been carried on. For 4 to 5 years, two devices have been investigated clinically. For many years, we have studied a rotary (but not centrifugal) pump that furnishes pulsatile flow without a valve and does not need external venting or a compliance chamber. It is a hypocycloidal pump based on the principle of the Maillard-Wankel rotary compressor. Currently made of titanium, it is activated by an electrical brushless direct-current motor. The motor-pump unit is totally sealed and implantable, without noise or vibration. This pump was implanted as a left ventricular assist device in calves. The midterm experiments showed good hemodynamic function. The hemolysis was low, but serious problems were encountered: blood components collecting on the gear mechanism inside the rotor jammed the pump. We therefore redesigned the pump to seal the gear mechanism. We used a double system to seal the open end of the rotor cavity with components polished to superfine optical quality. In addition, we developed a control system based on the study of the predicted shape of the motor current. The new design is now underway. We hope to start chronic experiments again in a few months. If the problem of sealing the bearing could be solved, the Cora ventricle could be used as permanent totally implantable left ventricular assist device.

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↗
PubMed1995

Clinical situations and results of cardiopulmonary support by peripheral access for resuscitation and recovery.

Use of cardiopulmonary support (CPS) by peripheral access with a membrane oxygenator has made considerable progress as a result of the development of centrifugal pumps, percutaneous cannulation, and preheparinized circuits. We have used CPS for resuscitation in 3 cases, for recovery after cardiotomy in 6 cases (myocardial insufficiency, 4; pulmonary arterial hypertension, 1; respiratory insufficiency, 1), and after heart transplantation in 1 case. Of these 10 patients, 3 died during CPS, 5 were successfully weaned, and 2 underwent heart transplantation. Use of CPS is expanding for emergency cardiac assistance. Installation is simple and rapid. It allows recovery of organs pending more invasive and costly techniques.

Adult↗
PubMed1995

Type A dissection of the thoracic aorta: use of MR imaging for long-term follow-up.

PURPOSE: To evaluate routine magnetic resonance (MR) imaging for long-term follow-up in patients who undergo surgery for type A aortic dissection. MATERIALS AND METHODS: Ninety-two MR examinations were performed in 36 patients. Standard spin-echo images were obtained with electrocardiographic gating (n = 92) and rapid images with a fast low-angle shot sequence and intravenous administration of gadopentetate dimeglumine (n = 25). All segments of the native thoracic aorta were evaluated. Anastomoses of the prosthesis and periprosthetic hematoma were carefully analyzed. RESULTS: Of 22 complications that occurred in 18 patients, 18 were diagnosed at MR imaging (nine false aneurysms and nine aneurysms distal to the graft). Nine patients underwent reoperation. The findings at MR imaging correlated with those at surgery. CONCLUSION: Routine follow-up with MR imaging should improve long-term survival in patients who survive emergency surgical repair of type A aortic dissection.

Aortic Dissection↗
PubMed1995

[Repeated heart valve replacements: prognosis and results].

In order to determine the prognosis of reoperation for valvular replacement, we reviewed the results of a consecutive series of 124 patients operated in the department between 1974 and 1992 (163 multi redo operations). There were 69 women and 55 men, with a mean age 48 years; 77% of the patients were in functional class III or IV. Operations were performed as an emergency in 30% of cases. Endocarditis was found in 24% of cases and was an important risk factor in this content. The main indications for reoperation were periprosthetic leakage in 28.8% of cases and failure of bioprostheses in 23.7%. The valvular replacement was simple in 61%, double in 32% and triple in 7% of cases. An associated procedure was necessary in 27% of cases. Mechanical devices were implanted in 62.3% of cases. Peroperative mortality was 3% and hospital mortality, mainly from cardiac causes, was 21.7% for the second, 20% for the third and 55.6% for the fourth reoperations. Operative mortality was dependent on the number or reoperations, functional class, emergency surgery, duration of bypass and cross-clamping time. Four per cent of patients were lost to follow-up and 30 patients died secondarily. The actuarial survival rate was 52% at 5 years and 33% at 10 years, actuarial survival rate without valvular complication was 41% at 5 years and 19% at 10 years but the functional results remained good with over 90% of patients in functional class I or II at the end of follow-up.

Adolescent↗
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

Right-sided aortic arch: surgical treatment of an aneurysm arising from a Kommerell's diverticulum and extending to the descending thoracic aorta with an aberrant left subclavian artery.

The case of a 44-year-old black man who presented with severe dysphagia, cough and chest pain caused by a 12-cm aneurysm developing from a Kommerell's diverticulum at the origin of an aberrant retro-oesophageal left subclavian artery is reported. The aortic arch and descending thoracic aorta were right sided. Diagnosis was established before operation by computed tomography, magnetic resonance imaging and arteriography. The aneurysm extended a considerable distance down the descending aorta and therefore the risk of postoperative paraplegia was considered to be high. Accordingly selective arteriography was performed to locate the Adamkievicz's artery which arose only 2 cm below the end of the aneurysm. Resection grafting of the aneurysm including the upper third of the descending aorta via right thoractomy was performed. The patient made an uneventful recovery and was discharged 20 days later. This case appears to be the first successful operation for this pathology.

Adult↗
PubMed1993

Diagnosis of prosthetic heart valve thrombosis. The respective values of transthoracic and transoesophageal Doppler echocardiography.

Early diagnosis of acute prosthetic thrombosis remains a challenge. In 20 patients with 23 thrombosed cardiac valves, we evaluated the respective value of transthoracic (TTE) and transoesophageal (TEE) Doppler echocardiography. According to the presence or absence of prosthetic obstruction by continuous-wave Doppler, prostheses were separated into two groups. Group 1 included nine thrombosed prostheses (8 mitral, 1 aortic) with severe obstruction. All patients presented with severe symptoms of heart failure. Transthoracic Doppler echocardiography allowed immediate diagnosis of prosthetic thrombosis, even in critically ill patients, showing (1) eccentric transprosthetic colour flow jets in all eight mitral prostheses, (2) severe obstruction on Doppler examination (mean gradient = 18 to 36 mmHg in eight mitral prostheses, and 69 mmHg in one aortic valve), and (3) direct echocardiographic evidence of thrombosis (i.e. thrombus or abnormal disc or leaflet motion) in four patients. All nine patients were immediately treated by surgery (n = 8) or fibrinolysis (n = 1) on the basis of TTE results only. TEE allowed better visualization of thrombus and restricted leaflet or disc motion, but had little influence on patient management. Group 2 included 14 thrombosed prostheses (10 mitral, 4 aortic) with mild or absent obstruction. In three patients with massive mitral prosthetic thrombosis, an associated minimal thrombosis of a prosthetic aortic valve was found at surgery, but was detected neither by TTE, nor by TEE. The 11 remaining patients with isolated partial mitral (n = 10) or aortic (n = 1) thrombosis. Clinical presentation was fever, cerebral embolism, or mild dyspnoea, but no heart failure. TTE was normal in all.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗
PubMed1992

[Plasma glycosylated residues demonstrated by proton NMR spectroscopy. Value in the detection of heart graft rejection].

In conjunction with biopsy and Doppler studies, we analysed by high resolution proton NMR spectroscopy the blood plasma of 22 heart transplant recipients. There was a significant variation in the glycosylated residues of proteins with the development of acute cardiac rejection. A more extensive study is underway to assess the sensitivity and specificity of this approach for the early diagnosis of acute cardiac rejection.

Acetylglucosamine↗
PubMed1992

[Right intra-atrial extension of hydatid cyst mimicking cardiac thrombosis. Apropos of a case].

The authors describe an unusual case of hydatid cyst inserted in the inferior vena cava and extending into the right atrium. The transoesoesophageal echocardiographic appearances were similar to those of a thrombus: the tumour was very mobile, echogenic, polylobular with a cord-like pedicle in the inferior vena cava. The pathological examination revealed a ruptured hydatid cyst. The mass and its insertion were not visible on CT scan or cavography. Transoesophageal echocardiography would therefore seem to be a very useful diagnostic method for tumours arising in the inferior vena cava and extending into the right atrium.

Cardiomyopathies↗
PubMed1991

[Surgical treatment of right-sided infective endocarditis].

Between 1980 and 1989, 8 patients (5 men, 3 women; mean age 30 years) were operated upon in our department of right-sided infective endocarditis. Six patients were heroin addicts and among these 3 were HIV positive and 2 had confirmed AIDS. The most frequently encountered microorganisms (6 cases) were staphylococci. It was decided to operate because of persistent infection and haemodynamic deterioration. The infection involved the pulmonary valve in only 1 of the 8 patients. Surgery was performed during the acute phase in 5 patients and was conservative in 6 patients, consisting of excision of the vegetations or valvulectomy combined or not with valvuloplasty. A high mortality rate (3/8 cases) was observed only among patients operated upon in the acute phase. This may be due to the underlying immunodeficiency and poor haemodynamic state of these patients. Among survivors, the long-term results were excellent, with no recurrent endocarditis and no death, and with only one subsequent operation, 4 years after the first one, for residual tricuspic valve regurgitation. This study shows that patients with right-sided infective endocarditis should be operated upon outside the acute phase of the disease and as soon as complications appear, and that surgery should preferably be conservative.

Acquired Immunodeficiency Syndrome↗
PubMed1991

[Periprosthetic false aneurysm after Bentall's operation: diagnosis with magnetic resonance imaging].

Periprosthetic false aneurysm due to dehiscence of a suture line represents a serious postoperative complications after Bentall's procedure, because of its asymptomatic presentation and spontaneous course towards progressive increase in size with high risk of sudden rupture. This type of complication justifies systematic radiologic follow-up. Magnetic Resonance Imaging, as proved by our two cases, is a reliable technique in the diagnosis of this complication requiring reoperation.

Adult↗