Evaluation of improved transvenous heartworm extraction brush in dogs with caval syndrome.

BACKGROUND: Heartworm infection in dogs is caused by Dirofilaria immitis and common in shelter animals and outdoors dogs. Caval syndrome can develop with severe infection and physical heartworm removal is essential with heartworm burdens. In this study, we used an improved transvenous heartworm extraction brush, which was expected to cause less cardiovascular damage and allow easier manipulation. OBJECTIVES: This study aims to evaluate efficacy of this improved transvenous heartworm extraction brush. METHODS: The brush was designed to improve upon the limitations of the previous brush-type devices. The brush was made of a polyvinyl chloride tube and threads of polyamides or polyglyconates. Metal material was inserted at the front tip for easy visualization under fluoroscopy. The eight dogs diagnosed with caval syndrome with large numbers of heartworms and pulmonary hypertension were used in this study. The removal procedure began with the dissection of the subcutaneous tissue around the right jugular vein. The device was inserted through the jugular vein. After insertion, the tube was rotated to catch the heartworms and extracted with the heartworms hanging on the threads. The procedure was repeated several times. Lastly, jugular vein and skin sutures were made. Adulticidal therapy was administered after heartworm removal. RESULTS: The mean number of removed heartworms was 10.5 ± 4.24 and mean number of remaining heartworms was 0.63 ± 1.06. Total procedure time was 72.63 ± 51.36. Except for three cases, heartworms were not detected on ultrasonography after the procedure. No procedure-related side effects were observed within the 1- to 2-mon. CONCLUSIONS: An improved transvenous heartworm extraction brush is efficient for heartworm removal in dogs with caval syndrome.

N-terminal pro-B-type natriuretic peptide levels in normotensive and hypertensive dogs with myxomatous mitral valve disease stage B.

BACKGROUND: Systemic hypertension affects the heart, and to the best of our knowledge, no study has investigated the effects of N-terminal pro-B-type natriuretic peptide (NT-proBNP) in dogs with myxomatous mitral valve disease (MMVD) stage B and systemic hypertension. This study aimed to investigate the blood level of NT-proBNP and assess the selected echocardiographic variables in dogs with MMVD stage B according to the presence of systemic hypertension or normal blood pressure and in dogs without MMVD. RESULTS: The study group comprised 37 dogs with stage B MMVD (normotensive group, n = 30; systemic hypertension group, n = 7) and 13 dogs without MMVD. We evaluated NT-proBNP, blood pressure, complete blood count (CBC), and serum chemistry in all 50 dogs. We performed electrocardiography, radiography, and echocardiography on 44 dogs (37 dogs with MMVD and 7 dogs without MMVD). The NT-proBNP concentrations showed significant intergroup differences (p < 0.001). Normotensive dogs with MMVD stage B (median [interquartile range]: 1083.5 [574.8-1912.8] pmol/L) and hypertensive dogs with MMVD stage B (2345.0 [1812.5-2533.0] pmol/L) showed significantly higher NT-proBNP concentrations than dogs without MMVD (504 [430-774] pmol/L, p = 0.009 and p < 0.001, respectively), and dogs in the systemic hypertension group showed significantly higher NT-proBNP concentrations than those in the normotensive group (p = 0.046). Mitral valve regurgitation velocity was significantly higher in dogs in the systemic hypertension group (6.11 [6.07-6.24] m/s) than in those in the normotensive group (5.53 [5.17-5.95] m/s, p = 0.006). The left atrial to aortic root ratio (LA/Ao), E-peak velocity, and left ventricular end-diastolic internal diameter corrected for body weight (LVIDDN) were significantly lower in dogs without MMVD than in dogs with MMVD stage B. CONCLUSIONS: These findings suggest that NT-proBNP concentrations are higher in dogs with MMVD stage B with systemic hypertension than in normotensive dogs with MMVD stage B. Therefore, clinicians should be aware that NT-proBNP could be elevated in the presence of systemic hypertension.

CT-guided instillation of 5% dextrose in water into the anterior pararenal space before renal radiofrequency ablation in a porcine model: positive and negative effects.

PURPOSE: To assess the positive and negative effects of computed tomographic (CT)-guided instillation of 5% dextrose in water (D5W) into the anterior pararenal space before renal radiofrequency (RF) ablation in a porcine model. MATERIALS AND METHODS: Under CT guidance, D5W was instilled into the right anterior pararenal space of 10 pigs and RF ablation performed in the right kidney. For the control lesions, RF ablation was performed in the left kidney of the same pigs without pretreatment with D5W. Approximately 1 week after RF ablation, bowel adhesion to both kidneys was compared by using a 5-point scale at open laparotomy, as follows: grade 0=no adhesion, grade 1=detachable adhesion, grade 2=grade 1 adhesion plus other adhesion to organs, grade 3=undetachable adhesion, and grade 4=bowel perforation. The areas of coagulation necrosis in both kidneys were compared at pathologic examination. RESULTS: Bowel adhesions to the right kidneys were classified as grade 0 in nine pigs and as grade 1 in one pig, whereas those to the left kidneys were classified as grade 2 in two pigs and as grade 3 in eight (P<.05). The mean areas of coagulation necrosis in right and left kidneys were 0.58 cm2+/-0.5 and 1.53 cm2+/-1.3, respectively (P<.05). CONCLUSIONS: CT-guided D5W instillation has a positive effect in reducing the amount of bowel adhesion injury during RF ablation. However, this technique may limit the area of coagulation necrosis in a swine model. Longer term pathologic evaluation is necessary to fully understand the effects of D5W instillation.

Vascular patches tissue-engineered with autologous bone marrow-derived cells and decellularized tissue matrices.

Synthetic polymer vascular patches used in cardiovascular surgery have shortcomings such as thrombosis, intimal hyperplasia, calcification, infection, and no growth potential. Tissue-engineered vascular patches using autologous vascular cells may solve these problems. In this study, we developed a tissue-engineered vascular patch using autologous bone marrow-derived cells (BMCs) and decellularized tissue matrices. Vascular smooth muscle cells and endothelial cells were differentiated from bone marrow mononuclear cells in vitro. Tissue-engineered vascular patches were fabricated by seeding these cells onto decellularized canine inferior vena cava matrices and implanted into the inferior vena cava of dogs. Three weeks after implantation, the tissue-engineered vascular patches were patent with no sign of thrombus formation. Histological, immunohistochemical, and electron microscopic analyses of the vascular patches retrieved 3 weeks after implantation revealed regeneration of endothelium and smooth muscle and the presence of collagen and elastin. BMCs labeled with a fluorescent dye prior to implantation were detected in the retrieved vascular patches, indicating that the BMCs survived after implantation and contributed to the vascular tissue regeneration. This study demonstrates that vascular patches can be tissue-engineered with autologous BMCs and decellularized tissue matrices.

Tracheal gas isufflation-aided mechanical ventilation during carbon dioxide-induced pneumoperitoneum in rabbits.

Despite numerous benefits of laparoscopic procedures, the serious hypercapnia and respiratory acidosis in hypercapnic patients with decreased pulmonary compliance during carbon dioxide-induced pneumoperitoneum (CDP) may be developed. Tracheal gas insufflation (TGI) has been shown to be a useful adjunct to controlled mechanical hypoventilation. This study was undertaken to identify whether TGI superimposed on controlled mechanical ventilation (CMV) improve ventilatory efficiency during CDP in rabbits. Sixteen paralyzed and anesthetized rabbits were used. The animals were assigned to two groups-CMV group: CMV alone; TGI group: CMV superimposed by TGI with flow rate of 2L/min. The animals were insufflated to intra-abdominal pressure of 8 mmHg with CO2 gas. Then, tidal volume (V(T)) was changed to maintain the set peak inspiratory pressure (PIP) value, while other ventilatory settings were kept constant. The set PIP value corresponding to 30, 60, and 90 min after the start of peritoneal insufflation of CO2 were 15, 22, and 25 cm H2O, respectively. During CDP with TGI, PaCO2 decreased significantly (p<0.01) from CMV without TGI of 82.1 +/- 14.1 to 47.5 +/- 5.5, 58.1 +/- 9.9 to 40.0 +/- 4.6, 47.1 +/- 9.4 to 32.7 +/- 5.1 mmHg at PIP of 15, 22, and 25 cm H2O, respectively. The inspired V(T) decreased significantly (p<0.05) from CMV without TGI of 18.4 +/- 3.9 to 12.8 +/- 2.8 ml at PIP of 15 cm H2O. TGI superimposed on CMV is more effective than CMV alone in enhancing ventilatory efficiency during CDP in rabbits.

Identification of differentially expressed mRNAs of the autologous vein graft after an arterial bypass in mongrel dogs.

PURPOSE: Intimal hyperplasia (IH) is characterized by vascular smooth muscle cell (VSMC) proliferation in the intima and subsequent accumulation of extracellular matrix. A variety of factors that might be considered as possible VSMC mitogens induce the specific gene expression of VSMC. This study was designed to identify differentially expressed mRNA by method using an mRNA differential display. METHODS: A bilateral femoropopliteal reverse saphenous vein bypass was performed on both hind limbs of mongrel dogs. At 4 and 8 weeks after the implantation, the vein bypass grafts were harvested. The total RNAs were extracted from each specimen and transcribed into the cDNAs. Amplified cDNAs using 16 sets of primers were separated on DNA sequencing gel. Differentially displayed bands were excised from the gel, cloned, and then sequenced. The sequences were compared with the National Center of Biotechnology Information nonredundant sequence database using the Basic Local Alignment Search Tool (BLAST) program. RESULTS: Forty-three bands were cloned and sequenced. A computer search revealed that 11 of them had similarities to known genes while 32 cDNAs had no similarities to any registered DNA sequence. CONCLUSIONS: We found several genes to be related to IH. Some of them had already had their function and sequence identified whereas some of them have yet to be identified. Further studies are necessary to determine the precise relationship between these genes and IH.