Search

Aims: We compared two procedures for local myocardial treatment: transepicardial versus transendocardial catheter injection. Transepicardial injections were performed under direct surgical visualization whereas transendocardial injections were performed using electrophysiological guidance. Methods: A left ventricle (LV) myocardial infarction (MI) was surgically created in 14 sheep. At 3 months, gadolinium was injected IV followed by the injection of super paramagnetic iron oxide (SPIO) into MI. Animals were divided in two groups: transepicardial injection (Group I) versus transendocardial (Group II) using “Cell-Fix” catheter injection. This catheter was developed to identify by electrophysiology the infarcted area and to stabilize injections suctioning the device to the endocardium. Postgadolinium delayed-enhancement magnetic resonance imaging (MRI) was performed to stain the infarct size. SPIO injections were used to assess the magnitude of the treated area. The ratio between SPIO black stained treatment areas and white gadolinium stained infarcted areas was calculated using MRI. Results: The electrophysiological recordings by the catheter for the MI versus normal LV wall were: R wave amplitude 4.16 versus 12.08 mV (P = 0.003), slew rate (slope of the signal) 0.36 V/s versus 1.04 V/s (P = 0.008). The ratio of the SPIO diffusion into the MI was 41.2 ± 8.1% for surgical and 63.7 ± 8.2% for percutaneous endocardial injections (P = 0.0132). Conclusion: MRI allows evaluation of the extent of local myocardial treatments. The differences shown between epicardial and endocardial injections concerning the distribution of SPIO can be justified by the methodology of injection and by a more precise MI detection by electrophysiology. In conclusion, electrophysiological recordings to guide injections is superior to direct surgical visualization in terms of injecting into infarcted tissue. [ABSTRACT FROM AUTHOR]

Objectives: Large animal experimental models of chronic heart failure (HF) permit repeated invasive assessment of cardiovascular function, and evaluation of new medical or surgical therapies. The existing models however fail to achieve stable and long-term HF. The aim of this study was to create a simple and stable chronic model of HF in goat, using both arteriovenous fistula and weekly intravenous doxorubicin injections.Methods: After a preliminary experiment on four goats receiving weekly 1 to 2 mg/kg of doxorubicin, six adult female goats, having had an arteriovenous fistula without signs or symptoms of heart failure, received weekly two different dosages of doxorubicin for 13 weeks: group A (n = 3) received 0.5 mg/kg and group B (n = 3) received 1 mg/kg. After a three-month period without medication, both groups received again 1 mg/kg for four weeks. Cardiac function was assessed by repeated electrocardiographic and echocardiographic examinations.Results: Four goats died during the medication period (one in group A, three in group B). During the period without medication a stable ventricular hypocontractility with left ventricular dilation was observed. Left ventricular dysfunction was more pronounced in group B, and was associated with clinical symptoms of HF.Conclusions: Arteriovenous fistula alone did not produce HF. Its association with doxorubicin injections provides a simple and stable chronic model of HF. This association allows reduction of the required doxorubicin dose and toxicity in animals and in the environment. Depending of the dose of doxorubicin, it is possible to obtain a model of heart dilatation and ventricular hypokinesia with or without clinical symptoms of HF, with a different mortality. [ABSTRACT FROM AUTHOR]