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Clinical Application of a Mechanical,
Bileaflet, Rotatabel, Valvar Prosthesis,
in Aortic Position

Almeida, Rui Manuel Sequeira;
Lima Jr., José Dantas; Kahrbek, Thomas;
Jorge, Amaury César; Loures, Danton Rocha

Instituto de Moléstias Cardiovasculares de Cascavel (IMCC) e
Universidade Estadual do Oeste do Paraná (UNIOESTE), Paraná, Brazil

RESUMO

ABSTRACT
Introduction: The use of mechanical valves is a normal issue in today's cardiovascular surgery. The main problem is the necessity for anticoagulants.
Objective: Study of the clinical application of ATS Medical Open Pivot™, in aortic position, from a clinical and laboratory point of view, during one year.
Material and Method: Thirty-four patients were studied, in whom an ATS valve was implanted in aortic position. Twenty-eight were male and six females, with a mean age of 40.2 years. Pre-operatively 11 patients were in NYHA class III and eight in IV, being 24 elective operations, 12 urgencies and four emergencies. The patients were evaluated trough an interview, physical and laboratorial examination, EKG, chest X-ray and 2-D echocardiography with color Doppler.
Results: The hospital mortality was 5.9%, from non-cardiac causes, and the main cause of morbidity was in 14.7% left ventricular failure. Late mortality was 3.1%. The actuarial survival curves, for a year, show 90.9% patient survival and 93.9% freedom from valve complications. At the end of the study 29 patients were in class I. The cardio-thoracic ratio, higher than 0.5in 91.2%, pre-operatively, became to normal range in 73.3%. The RNI was maintained between 1.5 and 2, during the study. The mean transvalvar gradient was 12,2 ± 5,9 mmHg.
Discussion: There was an improvement in all indexes for ventricular regression. A correlation between maximum transvalvar gradient and lactic dehydrogenase was established, as well as between left ventricular end systolic volume and ejection fraction
Conclusion: The authors conclude that the ATS prosthesis is an excellent alternative, as an aortic valvar replacement, due to the fact that has a low rate of valve complications, during the period studied, with the advantage of a low index of RNI.

 

OBJECTIVE
   To present the clinical application of ATS Medical Open Pivot™, in aortic position, from a clinical and laboratory point of view, during one year, at the Cardiovascular Surgical Unit, of the "Instituto de Moléstias Cardiovasculares de Cascavel", Cascavel, Paraná, Brazil.

INTRODUCTION
   The development of a new cardiac valve prosthesis, capable of substituting, without restrictions, a natural cardiac valve, as represented always, a great challenge to the Human imagination and technology. Among all cardiac valve prostheses, at reach to the cardiovascular surgeon, the metallic prostheses are the ones most used at world level. Their main problem is a consequence of the necessity for life-time use of anticoagulants, which is adjusting their INR values specifically, for a different prosthesis and a different patient.

   The bileaflet valves are the latest ones to arrive to our clinical practice and the ones, in which a lower INR level, can be used. One of the newest representatives of these valves is the ATS Medical Open Pivot™, seen below. (Fig. 1)

Figure 1

PATIENTS AND METHODS
   Between May 1996 and October 1997, at the Cardiovascular Surgical Unit, of the "Instituto de Moléstias Cardiovasculares de Cascavel", Cascavel, Paraná, Brazil, 34 patients were submitted to an aortic valve replacement, by a bileaflet mechanical, rotational, heart valve (ATS Medical Open Pivot™, Standard type).

   From this group, of 34 patients, there were 28 male and 6 female with a mean age of 40.2 years. Pre-operatively, 11 patients were in NYHA functional class IV (32.4%), 15 in class III (44.1%) and eight in class II (23.5%), being 24 elective procedures, 12 urgent and four emergencies. The group was followed-up, for a year, in 97.1%.

   There was in 44,1% (15/34) association with other cardiac disease. The most commom association was with mitral valve disease (8), coronary artery bypass (3), congenital defects (2) and dissecting aortic aneurysm (1).

   All patients were studied pre and postoperatively, by an interview, physical and laboratory exams, which included blood exams (globular volume, haematocrit, protrombin time and lactic dehydrogenase- LDH), EKG, chest X-ray and 2-D echo Doppler color, with a purpose of getting the following data: ejection fraction, percentual shortening, left ventricular end systolic and diastolic volumes, maximum and medium aortic velocity flow, maximum and medium transvalvular gradient and septal and posterior left ventricular wall thickness.

RESULTS
   The hospital mortality was 5.9%, due to non-cardiac causes and the most important complication was left ventricular failure (14.7%). The late mortality was 3.1%. The actuarial survival curves, at the end of one year, showed a 90.9% patient survival and a 93.9% freedom of valvular problems. At the end of the study, 29 patients were in NYHA class I. The cardio-thoracic index, greater than 0.5 in 91.2% of the patients, pre-operatively, return to normal values in 73.3%. It was possible to maintain the INR values between 1.5 and 2.0, without any prostheses complications. The LDH values' were above the normal range, during the follow-up period, but was a reliable parameter for seric hemolysis. The mean valvular gradient was 12.2 ± 5.9 mmHg. (Fig. 2)

Figure 2

   There was a left ventricular remodelling, during the all study, with the regression of the systolic and diastolic left ventricular volumes and the thickness off the septal and parietal. There was a correlation between the maximum transvalvular gradient and the LDH, as well as between end systolic volume and the ejection fraction. Finally, there was only a small group of patients, who complained about the valve noise.
The actuarial survival of curve of the all group is shown below. (Fig. 3)

Figure 3

DISCUSSION
   The ATS valve prosthesis, when being made and after its clinical application in 1992, had the intuit of improving the negative points of other bileaflet metallic valves and making a valve that "Advanced the Standard". The most important features of this prosthesis are the design of the pivot, the rotation in itself, the low profile, the orificial geometrical area, the opening angle of the leaflets, the radiopacity, and the sound due to the leaflets closure.
Despite the group being an heterogeneous group with patients with preponderance of stenotic or insufficiency lesion associated with mitral, coronary arteries, aortic aneurism and congenital disease, the overall results are similar tto those presented in the international literature.

   During the all study there was an improvement in all indexes for ventricular regression. A correlation between maximum transvalvar gradient and lactic dehydrogenase was established, as well as between left ventricular end systolic volume and ejection fraction

CONCLUSIONS
   This study is able to conclude, that the ATS Medical Open Pivot™ is a excellent alternative, for an aortic valve substitute, as it has a low index of complications, during the follow-up period, with the advantage of being able to have a low INR, comparing with other prostheses, and that a reshaping of the left ventricle occurs due to its good haemodynamic performance.

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Aplicação Clínica de Prótese Valvar Mecânica, de Duplo Folheto, Giratória, em Posição Aórtica

RESUMO
Introdução: O uso de próteses mecânicas é comum em cirurgia cardiovascular. O grande óbice é a necessidade em usar anticoagulantes.
Objetivo: Estudo da aplicação clínica da prótese ATS Medical Open Pivot™, em posição aórtica, através da análise clínica e laboratorial prospectiva, durante o primeiro ano.
Material e Método: Foram estudados 34 pacientes, nos quais se procedeu ao implante, da prótese ATS. Destes 28 eram masculinos e seis femininos, com uma média de 40,2 anos. No pré-operatório, 11 pacientes encontravam-se na classe funcional IV, 15 na III e oito na II, tendo sido realizadas 24 cirurgias eletivas, 12 de urgência e quatro de emergência. Os pacientes foram avaliados, através de anamnése, exames físico e laboratoriais, eletrocardiograma, radiografia do tórax e ecocardiograma bidimensional com Doppler colorido.
Resultados: A mortalidade hospitalar foi de 5,9%, devida a causas não cardíacas, sendo a complicação mais freqüente, insuficiência do VE (14,7%). A mortalidade tardia foi 3,1%. As curvas atuariais, ao final de um ano, mostraram 90,9%, de sobrevivência, e 93,9%, de próteses livres de complicações. No final do estudo 29 pacientes estavam em classe funcional I. O índice cardiotorácico, superior a 0,5 em 91,2% dos pacientes, no pré-operatório, retornou a valores normais em 73,3%. Foi possível durante o estudo manter os pacientes com um INR entre 1,5 e 2. O gradiente médio das próteses implantadas, foi 12,2 ± 5,9 mmHg.
Discussão: Houve melhora dos índices de regressão ventricular, em todo o estudo. Verificou-se uma correlação entre gradiente máximo transvalvar e desidrogenase lática sérica e entre volume sistólico final e fração de ejeção do ventrículo esquerdo.
Conclusão: Conclui-se que a prótese ATS é uma excelente alternativa, como substituto valvar aórtico, porque teve um baixo índice de complicações associadas, durante o período de estudo, com a vantagem de poder manter um nível de INR abaixo, dos anteriormente usados.

 

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2nd Virtual Congress of Cardiology

Dr. Florencio Garófalo
Steering Committee
President
Dr. Raúl Bretal
Scientific Committee
President
Dr. Armando Pacher
Technical Committee - CETIFAC
President
fgaro@fac.org.ar
fgaro@satlink.com
rbretal@fac.org.ar
rbretal@netverk.com.ar
apacher@fac.org.ar
apacher@satlink.com

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