Jarbas J Dinkhuysen

Risk factors associated with cardiac surgery during pregnancy

BACKGROUND This study is aimed at analyzing risk factors for fetal and maternal mortality in cardiac surgery during pregnancy. METHODS Seventy-four pregnant women underwent cardiac surgery and 58 (78.3%) were followed. The most frequent pathology was valve disease (93.2%). Mitral valve disease was the most prevalent (72.9%), and mitral commissurotomy or replacement was required in 78% of the cases. Most were in functional class III or IV and mean gestational age was 22 weeks. RESULTS There was functional class improvement after surgery (91% into class I or II), and 70.4% were restored to sinus rhythm. Twenty percent required reoperation. There were five maternal deaths (8.6%) and 11 fetal deaths (18.6%). Several aspects were considered as contributing risk factors for maternal mortality, such as the use of vasoactive drugs and other preoperative medications, age, kind of surgery, reoperation, and functional class. Functional class was the factor that predicted higher risk for maternal death. As to fetal mortality, several factors played a role, such as maternal age more than 35 years, functional class, reoperation, emergency surgery, type of myocardial protection, and anoxic time. CONCLUSIONS Cardiac surgery during pregnancy is associated with acceptable maternal and fetal mortality rates. These rates may be even lower if the factors mentioned above are maintained under control.

Characteristics of a Blood Pump Combining the Centrifugal and Axial Pumping Principles: The Spiral Pump

Two well-known centrifugal and axial pumping principles are used simultaneously in a new blood pump design. Inside the pump housing is a spiral impeller, a conically shaped structure with threads on the surface. The worm gears provide an axial motion of the blood column through the threads of the central cone. The rotational motion of the conical shape generates the centrifugal pumping effect and improves the efficiency of the pump without increasing hemolysis. The hydrodynamic performance of the pump was examined with a 40% glycerin-water solution at several rotation speeds. The gap between the housing and the top of the thread is a very important factor: when the gap increases, the hydrodynamic performance decreases. To determine the optimum gap, several in vitro hemolysis tests were performed with different gaps using bovine blood in a closed circuit loop under two conditions. The first simulated condition was a left ventricular assist device (LVAD) with a flow rate of 5 L/min against a pressure head of 100 mm Hg, and the second was a cardiopulmonary bypass (CPB) simulation with a flow rate of 5 L/min against 350 mm Hg of pressure. The best hemolysis results were seen at a gap of 1.5 mm with the normalized index of hemolysis (NIH) of 0.0063 ± 0.0020 g/100 L and 0.0251 ± 0.0124 g/100 L (mean ± SD; n = 4) for LVAD and CPB conditions, respectively.

Transplante cardíaco no Instituto Dante Pazzanese de Cardiologia: análise da sobrevida

From November 30, 1991 to August 31, 2000, 80 cardiac transplants have been analyzed retrospectively at Instituto Dante Pazzanese de Cardiologia. Seventy percent of the recipient were male, and the recipient average was 44.8 years(range: 7 to 69 years). Twelve patients(15%) were considered priority, receiving inotropic drug support at the moment of transplantation. The diagnosis of the recipients included primary dilated cardiomiopathy (37.5%), ischemic cardiomiopathy (33.75%), cardiomiopathy by Chagas disease (17.5% ) and others (11.25%). Seventy eight transplants were orthotopic, and two heterotopic. Surgical technique used was bicaval/bipulmonar (63.75%), atrial (27.5%), bicaval/unipulmonar (6.25%) and heterotopic (2.5%). The 30 day mortality for all patients was 18.75%. The survival after orthotopic transplant in one year was of 72.7%; in five years was 61.5%, and in seven years was of 56.4%. The survival after transplant was related to the following variables: age, cause of death and sex of the donor, and wheter the transplant was or not the patients first cardiac surgery .

Implantable centrifugal blood pump with dual impeller and double pivot bearing system: electromechanical actuator, prototyping, and anatomical studies.

An implantable centrifugal blood pump has been developed with original features for a left ventricular assist device. This pump is part of a multicenter and international study with the objective to offer simple, affordable, and reliable devices to developing countries. Previous computational fluid dynamics investigations and wear evaluation in bearing system were performed followed by prototyping and in vitro tests. In addition, previous blood tests for assessment of normalized index of hemolysis show results of 0.0054±2.46 × 10⁻³ mg/100 L. An electromechanical actuator was tested in order to define the best motor topology and controller configuration. Three different topologies of brushless direct current motor (BLDCM) were analyzed. An electronic driver was tested in different situations, and the BLDCM had its mechanical properties tested in a dynamometer. Prior to evaluation of performance during in vivo animal studies, anatomical studies were necessary to achieve the best configuration and cannulation for left ventricular assistance. The results were considered satisfactory, and the next step is to test the performance of the device in vivo.

A New Model of Centrifugal Blood Pump for Cardiopulmonary Bypass: Design Improvement, Performance, and Hemolysis Tests

A new model of blood pump for cardiopulmonary bypass (CPB) application has been developed and evaluated in our laboratories. Inside the pump housing is a spiral impeller that is conically shaped and has threads on its surface. Worm gears provide an axial motion of the blood column. Rotational motion of the conical shape generates a centrifugal pumping effect and improves pumping performance. One annular magnet with six poles is inside the impeller, providing magnetic coupling to a brushless direct current motor. In order to study the pumping performance, a mock loop system was assembled. Mock loop was composed of Tygon tubes (Saint-Gobain Corporation, Courbevoie, France), oxygenator, digital flowmeter, pressure monitor, electronic driver, and adjustable clamp for flow control. Experiments were performed on six prototypes with small differences in their design. Each prototype was tested and flow and pressure data were obtained for rotational speed of 1000, 1500, 2000, 2500, and 3000 rpm. Hemolysis was studied using pumps with different internal gap sizes (1.35, 1.45, 1.55, and 1.7 mm). Hemolysis tests simulated CPB application with flow rate of 5 L/min against total pressure head of 350 mm Hg. The results from six prototypes were satisfactory, compared to the results from the literature. However, prototype #6 showed the best results. Best hemolysis results were observed with a gap of 1.45 mm, and showed a normalized index of hemolysis of 0.013 g/100 L. When combined, axial and centrifugal pumping principles produce better hydrodynamic performance without increasing hemolysis.

Bomba sangüínea espiral: concepção, desenvolvimento e aplicação clínica de projeto original

Introduction: This paper addresses an original project that encompasses the concept, development, and clinical application of a helical bypass pump using the association of the centrifuge and axial propulsion forces based on the Archimedes principle, referred to as Spiral Pump. This project has obtained Brazilian Patent and a Preliminary International Report defining it as an invention. Methods: We seek to evaluate the homodynamic capacity and the impact of its application to the blood cells by means of experimental “in vitro” tests, such as Hydrodynamic Efficiency, Normalized Hemolytic, and Flow Visualization. The “in vivo” experimental tests were carried-out in lambs submitted to bypass for 6 hours and in 43 patients undergoing bypass heart surgery using the Spiral Pump. Results: When the rotor – plastic carcass gap was 1.5 mm, the generated flow was nearly 9 L/min; pressure above 400 mmHg at 1500 rpm, normalized hemolytic indexes not superior to 0.0375 g/1001 under high-flow and pressure conditions, and by the flow visualization at the entrance and exit of the pump, as well as the extremity of the spindles. At the “in vivo” tests in the lambs, the pump was capable of maintaining adequate pressure and the Free Hemoglobin ranged between 16.36 mg% and 44.90 mg%. Evaluating the results of the 43 patients using this pump in bypass heart operations we observed that the Free Hemoglobin ranged from 9.34 mg% to 44.16 mg% before and after surgery, respectively; the Serum Fibrinogen from 236.65 mg% to 547.26 mg%; Platelet Blood Count from 152.465 to 98.139; and the Lactic Dehydrogenase from 238.12 mg% to 547.26

Bicaval/bipulmonary orthotopic heart transplantation

The author describes a technique of performing bicaval/double-lung heart transplantation including the evaluation, harvesting and conservation of the donated organ. Additionally, the regime of pre-operative immunosuppression, the techniques of myocardial protection, resection of the native heart and implantation of the donated organ are described.

Testes in vitro e in vivo com o Coração Artificial Auxiliar (CAA): um novo modelo de coração artificial totalmente implantável e heterotópico

A miniaturized artificial heart is being developed in the authors laboratories, the Auxiliary Total Artificial Heart (ATAH). This device is an electromechanically driven ATAH using a brushless direct current (DC) motor fixed in a center aluminum piece. This pusher plate type ATAH is controlled based on Frank-Starlings law. The beating frequency is regulated through the change of the left preload, assisting the natural heart in obtaining adequate blood flow. With the miniaturization of this pump, the average sized patient can have the surgical procedure of implantation in the right thoracic cavity performed without removal of the natural heart. The left and right stroke volumes are 35 ml and 32 ml, respectively. In vitro tests were made and the performance curves demonstrated that the ATAH produces 5L/min of cardiac output at 180 bpm (10 mmHg of left inlet mean pressure and 100 mmHg of left outlet mean pressure). Preliminary acute In vivo tests were performed in two sheeps with 50 ± 5 kg, during 5 hours. The ATAH performance is satisfactory for helping the natural heart to obtain the required blood flow and arterial pressure. With the ATAH and the natural heart working simultaneously the ATAH control system is simpler, also the risks of a fatal misoperation is minor compared to a total artificial heart, for patients that still present some cardiac function.A miniaturized artificial heart is being developed in the authors laboratories, the Auxiliary Total Artificial Heart (ATAH). This device is an electromechanically driven ATAH using a brushless direct current (DC) motor fixed in a center aluminum piece. This pusher plate type ATAH is controlled based on Frank-Starlings law. The beating frequency is regulated through the change of the left preload, assisting the natural heart in obtaining adequate blood flow. With the miniaturization of this pump, the average sized patient can have the surgical procedure of implantation in the right thoracic cavity performed without removal of the natural heart. The left and right stroke volumes are 35 ml and 32 ml, respectively. In vitro tests were made and the performance curves demonstrated that the ATAH produces 5L/min of cardiac output at 180 bpm (10 mmHg of left inlet mean pressure and 100 mmHg of left outlet mean pressure). Preliminary acute In vivo tests were performed in two sheeps with 50 ± 5 kg, during 5 hours. The ATAH performance is satisfactory for helping the natural heart to obtain the required blood flow and arterial pressure. With the ATAH and the natural heart working simultaneously the ATAH control system is simpler, also the risks of a fatal misoperation is minor compared to a total artificial heart, for patients that still present some cardiac function.

Hybrid treatment of aortic arch disease

Introduction The management of thoracic aortic disease involving the ascending aorta, aortic arch and descending thoracic aorta are technically challenging and is an area in constant development and innovation. Objective To analyze early and midterm results of hybrid treatment of arch aortic disease. Methods Retrospective study of procedures performed from January 2010 to December 2012. The end points were the technical success, therapeutic success, morbidity and mortality, neurologic outcomes, the rate of endoleaks and reinterventions. Results A total of 95 patients treated for thoracic aortic diseases in this period, 18 underwent hybrid treatment and entered in this study. The average ages were 62.3 years. The male was present in 66.7%. The technical and therapeutic success was 94.5% e 83.3%. The perioperative mortality rate of 11.1%. There is any death during one-year follow- up. The reoperation rates were 16.6% due 2 cases of endoleak Ia and one case of endoleak II. There is any occlusion of anatomic or extra anatomic bypass during follow up. Conclusion In our study, the hybrid treatment of aortic arch disease proved to be a feasible alternative of conventional surgery. The therapeutic success rates and re- interventions obtained demonstrate the necessity of thorough clinical follow-up of these patients in a long time.

Manuseio da deiscência do esterno no pós-operatório de cirurgia cardíaca

No periodo de dezembro de 1987 a dezembro de 1989, 906 pacientes foram submetidos a cirurgia cardiaca com circulacao extracorporea, no Instituto Dante Pazzanese de Cardiologia, sendo 43% coronarianos, 37% valvares, 17% congenitos e 3% outros. Dentre eles, observou-se, na fase intra-hospitalar de pos-operatorio, a ocorrencia de 19 casos de deiscencia parcial ou total da toracotomia mediana (2%), que ocorreu, em media, ao redor da 1o semana de pos-operatorio, tendo sido a reintervencao cirurgica por volta da 3o semana. As culturas mostraram predominio de germes gram positivos e poucos casos de gram negativos e fungos. Em apenas um caso nao foi isolado qualquer agente infeccioso. Neste grupo de pacientes, constatou-se a presenca de fatores predominantes, tais como diabetes, obesidade, doenca pulmonar obstrutiva cronica (DPOC) e tempo prolongado de cirurgia (media de 6 horas). Houve predominio de pacientes adultos, cujas idades variaram de 40 a 67 anos, media de 53 anos (89%). Constatou-se que, em 84% dos pacientes, a arteria mamaria interna foi utilizada como enxerto na revascularizacao cirurgica do miocardio. Alem das medidas gerais de terapeutica local e sistemica com antibioticos especificos, visando ao combate dos agentes infecciosos e a consequente esterilizacao da ferida, os pacientes eram conduzidos a sala de operacao, procedendo-se a limpeza e desbridamento dos planos cirurgicos, incluindo o esterno, deixando-se, em alguns casos, irrigacao continua com solucao de povidine. Em dois pacientes foi realizada rotacao de retalho miocutâneo, devido a refratariedade ao tratamento. De cinco casos de mediastinite, tres faleceram por falencia de multiplos orgaos e sepsis. O grupo restante apresentou boa evolucao, tendo obtido alta hospitalar apos a 3o semana da reintervencao, com boa cicatrizacao da ferida operatoria.