Assessment of a new experimental model of isolated right ventricular failure.

We assessed a new experimental model of isolated right ventricular (RV) failure, achieved by means of intramyocardial injection of ethanol. RV dysfunction was induced in 13 mongrel dogs via multiple injections of 96% ethanol (total dose 1 mL/kg), all over the inlet and trabecular RV free walls. Hemodynamic and metabolic parameters were evaluated at baseline, after ethanol injection, and on the 14th postoperative day (POD). Echocardiographic parameters were evaluated at baseline, on the sixth POD, and on the 13th POD. The animals were then euthanized for histopathological analysis of the hearts. There was a 15.4% mortality rate. We noticed a decrease in pulmonary blood flow right after RV failure (P = 0.0018), as well as during reoperation on the 14th POD (P = 0.002). The induced RV dysfunction caused an increase in venous lactate levels immediately after ethanol injection and on the 14th POD (P < 0.0003). The echocardiogram revealed a decrease in the RV ejection fraction on the sixth and 13th PODs (P = 0.0001). There was an increased RV end-diastolic volume on the sixth (P = 0.0001) and 13th PODs (P = 0.0084). The right ventricle showed a 74% +/- 0.06% transmural infarction area, with necrotic lesions aged 14 days. Intramyocardial ethanol injection has allowed the creation of a reproducible and inexpensive model of RV failure. The hemodynamic, metabolic, and echocardiographic parameters assessed at different protocol times are compatible with severe RV failure. This model may be useful in understanding the pathophysiology of isolated right-sided heart failure, as well as in the assessment of ventricular assist devices.

Padronização da anestesia em suínos para procedimentos cirúrgicos cardiovasculares experimentais / Standardization of anesthesia in swine for experimental cardiovascular surgeries / Estandarización de la anestesia en cerdos para procedimientos quirúrgicos cardiovasculares experimentales

JUSTIFICATIVA E OBJETIVO: Embora sejam os cães os animais mais utilizados em Cirurgia Experimental, nota-se crescente utilização de ovinos, bovinos e suínos como modelos para experimentação científica. Assim, faz-se necessário maior aprendizado de seu tratamento e padronizações básicas para os procedimentos cirúrgicos mais complexos em suínos. O objetivo foi avaliar a sedação e analgesia, obtidas pela injeção intramuscular de midazolam e cetamina e anestesia local com lidocaína a 2 por cento sem vasoconstritor, na realização de traqueostomia, dissecção de artéria e veia femorais. MÉTODO: A freqüência cardíaca e o reflexo córneo-palpebral foram avaliados logo no início da sedação, durante os procedimentos cirúrgicos descritos e após seu término. Foram utilizados oito suínos fornecidos por fazendas locais sem tratamento prévio da raça Large White, com peso de 35 a 42 quilos que receberam injeção intramuscular de 22 mg.kg-1 de cetamina e 0,3 mg.kg-1 de midazolam. RESULTADOS: A abordagem anestésica nesses animais, de difíceis intubação e acesso aos vasos profundos, provou ser segura para sedação e analgesia através do método utilizado: acesso intramuscular. CONCLUSÃO: Obteve-se adequado plano de anestesia para o procedimento proposto.

BACKGROUND AND OBJECTIVES: Although dogs are the animals used more often in Experimental Surgeries, the use of sheep, bovine, and swine as models for scientific experiments has been growing. Thus, further learning on the treatment and basic standardization of more complex surgeries in swine are necessary. The objective of this study was to evaluate sedation and analgesia, obtained by the intramuscular administration of midazolam and ketamine, and local anesthetics with 2 percent lidocaine without vasoconstrictor, in tracheostomy and dissection of femoral artery and vein. METHODS: The heart rate and corneal-palpebral reflex were evaluated at the beginning of sedation, during the surgical procedures, and at the end of those procedures. Eight Large White swine, without prior treatment, weighing 35 to 42 kg were provided by local farms. They received intramuscular injections of 22 mg.kg-1 of ketamine and 0.3 mg.kg-1 of midazolam. RESULTS: The anesthetic approach on those animals, who present both difficult intubation and access to deep vessels, proved to be safe for sedation and analgesia by the method chosen: intramuscular administration. CONCLUSIONS: An adequate plane of anesthesia for the proposed procedure was achieved.

JUSTIFICATIVA Y OBJETIVOS: Aunque los perros sean los animales más a menudo usados en Cirugía Experimental, se nota un aumento en la utilización de los ovinos, bovinos y porcinos como modelo para experimentación científica. De esa forma, se hace necesario aprender más con su tratamiento y estandarizaciones básicas para los procedimientos quirúrgicos más complejos en porcinos. El objetivo fue evaluar la sedación y la analgesia obtenidas por la inyección intramuscular de midazolán y la cetamina y anestesia local con lidocaína a un 2 por ciento sin vasoconstrictor, en la realización de traqueostomía, disección de arteria y vena femorales. MÉTODO: La frecuencia cardíaca y el reflejo córneo-palpebral fueron evaluados inmediatamente al inicio de la sedación, durante los procedimientos quirúrgicos descritos y después en su conclusión. Se utilizaron ocho porcinos que fueron suministrados por haciendas de la región sin tratamiento previo de la raza Large White, con peso de 35 a 42 kilos que recibieron inyección intramuscular de 22 mg.kg-1 de cetamina y 0.3 mg.kg-1 de midazolán. RESULTADOS: El abordaje anestésico en esos animales, de difícil intubación y acceso a los vasos profundos, demostró ser seguro para la sedación y analgesia a través del método utilizado: el acceso intramuscular. CONCLUSIÓN: Se obtuvo un adecuado plan de anestesia para el procedimiento propuesto.

Standardization of anesthesia in swine for experimental cardiovascular surgeries.

BACKGROUND AND OBJECTIVES: Although dogs are the animals used more often in Experimental Surgeries, the use of sheep, bovine, and swine as models for scientific experiments has been growing. Thus, further learning on the treatment and basic standardization of more complex surgeries in swine are necessary. The objective of this study was to evaluate sedation and analgesia, obtained by the intramuscular administration of midazolam and ketamine, and local anesthetics with 2% lidocaine without vasoconstrictor, in tracheostomy and dissection of femoral artery and vein. METHODS: The heart rate and corneal-palpebral reflex were evaluated at the beginning of sedation, during the surgical procedures, and at the end of those procedures. Eight Large White swine, without prior treatment, weighing 35 to 42 kg were provided by local farms. They received intramuscular injections of 22 mg.kg of ketamine and 0.3 mg.kg(-1) of midazolam. RESULTS: The anesthetic approach on those animals, who present both difficult intubation and access to deep vessels, proved to be safe for sedation and analgesia by the method chosen: intramuscular administration. CONCLUSIONS: An adequate plane of anesthesia for the proposed procedure was achieved.

Desenvolvimento de uma protese de ventrículo artificial implantável / Development of a prosthesis of implanted artificial ventricle

O objetivo deste trabalho foi o desenvolvimento de uma prótese de ventrículo artificial implantável (VAI), para utilização em pacientes com insuficiência cardíaca profunda que necessitam de assistência circulatória mecânica, como ponte para transplante de coração. Foi utilizado um programa CAD (Microstation) para o projeto mecânico do VAI. O dispositivo apresenta uma membrana livre fixada entre duas crianças de titânio, seu acionamento é do tipo pneumático. O dispositivo foi projetado para ser implantado na cavidade abdominal e conectado ao coração nativo via ápice do ventrículo esquerdo e aorta, por meio de cânulas confeccionados em silicone, acopladas a válvulas biológicas de pericárdio bovino.

Abstract - This paper describes the design of an implantable artificial ventricular assist device to support the heart as a bridge to heart transplantation, in patients with profound cardiac failure. The artificial ventricle presented has a free floating membrane, dividing two titanium carcass. The driving unit is pneumatic. Two silicone cannulae are used to conect the device to the patient's heart ( left ventricle apex and aorta). Each cannula is eqquiped with one bovine pericardium valve. A computer program (Microstation) was utilized to provide volumetric calculus, bidimensional and tridimensional visualization to optimize the design