Assessment of myocardial viability in a porcine model of chronic coronary artery stenosis with dual dose dobutamine magnetic resonance imaging.

In a non-surgical porcine coronary stenosis model resulting in chronic left ventricle dysfunction, we aimed in this study to evaluate the potential of magnetic resonance imaging (MRI) to distinguish dysfunctional but viable from necrotic myocardium by using multiple levels of dobutamine inotropic stimulation during a cine MRI protocol (F.P. van Rugge et al.

A nonsurgical porcine model of left ventricular dysfunction. Validation of myocardial viability using dobutamine stress echocardiography and positron emission tomography.

BACKGROUND: Although several short-term animal models of stunning and hibernation have been studied extensively, it has been difficult to produce a consistent animal model of chronic hibernation. The aim of the present study was to develop a nonsurgical porcine stent model of coronary stenosis in order to investigate the relationship between chronic dysfunctional myocardium and viability using 2D-echo, dobutamine stress echo (DSE) and positron emission tomography (PET). METHODS AND RESULTS: Focal progressive coronary stenosis was induced by implantation of an oversized stent in the left anterior descending (LAD) and/or circumflex (LCX) coronary artery in a total of 115 pigs, according to various experimental protocols: copper stent in the LAD (group I, n = 5); noncoated stainless steel stent in the LAD combined with balloon overstretch (group II, n = 7); poly(organo)phosphazene-coated stent in the LAD (group III, n = 77); and poly(organo)phosphazene-coated stent in both the LAD and the LCX (group IV, n = 26).

Optimal dosing of intravascular low-power red laser light as an adjunct to coronary stent implantation: insights from a porcine coronary stent model.

Background: It is believed that restenosis following coronary interventions is the result of endothelial denudation that leads to thrombus formation, vascular remodeling, and smooth muscle cell proliferation. Low-power red laser light (LPRLL) irradiation enhances endothelial cell growth in vitro and in vivo, and reduces restenosis in animal models. The present study investigated the optimal dose of intravascular LPRLL therapy in the prevention of in-stent stenosis in a porcine coronary stent model.

Quantification of the spectrum of changes in regional myocardial function during acute ischemia in closed chest pigs: an ultrasonic strain rate and strain study.

The objectives of this study were to define the spectrum of regional myocardial function changes during acute ischemia in closed chest animals by using newly developed ultrasonic strain rate and strain indexes derived from regional color Doppler myocardial imaging (CDMI) velocity data. Myocardial ischemia was induced in 18 pigs either with acute total 20-second occlusions (group 1, n = 12) or graded hypoperfusion (40 to 0 mL/min, group 2, n = 6) of the circumflex coronary artery. In addition, a dobutamine challenge (5 to 10 microg/kg per minute) was performed during sustained subtotal ischemia (10 mL/min) in group 2.

Changes in systolic and postsystolic wall thickening during acute coronary occlusion and reperfusion in closed-chest pigs: Implications for the assessment of regional myocardial function.

The aim of the study was to characterize the impact of short-lived total coronary occlusions in closed-chest pigs on radial wall thickening within the "at-risk" myocardial segment by using gray-scale M-mode echocardiography. Twelve pigs underwent a series of 20-second total circumflex coronary artery occlusions with an angioplasty balloon. Myocardial thickening/thinning indexes were continuously monitored before ischemia, during ischemia, and on reperfusion by high-resolution M-mode recordings of the posterior wall obtained from parasternal views.

Intravascular low-power red laser light as an adjunct to coronary stent implantation: initial clinical experience.

Low-power red laser light (LPRLL) irradiation enhances endothelial cell growth in vitro and in vivo and reduces restenosis in animal models. The present study reports the preliminary clinical experience in our center. Eighty-one patients were treated with LPRLL, 30 mW/1 min, for in-stent restenosis (n = 27), elective stenting for recurrent restenosis (n = 16), and stenting for treatment of a suboptimal PTCA result (n = 38).

Evaluation of the biocompatibility of two new diamond-like stent coatings (Dylyn) in a porcine coronary stent model.

Unlabelled: Hydrogenated diamond-like carbon films (DLC, a-C:H), deposited using plasma-assisted or ion beam-assisted techniques, offer great potential as self-lubricating coatings in many tribological applications. Additionally, studies on biocompatibility have shown that DLC is an inert, impervious hydrocarbon with properties suitable for use in the biomedical field. One particular class of modified DLC coatings are diamond-like nanocomposite coatings (DLN or Dylyn , Bekaert, Kortrijk, Belgium), which offer promising solutions for many industrial applications.

Experimental Evaluation of a New Tubular Coronary Stent (V-Flexª).

The safety, efficacy, angiographic and histological effects of a new 316 L, SS seamless stainless steel tubular stent (V-Flexª, Global Therapeutics, Broomfield, Colorado) was evaluated in a porcine coronary and peripheral artery model. Implantation in the right coronary artery was successful in all 16 pigs. Eight pigs were angiographically controlled after 6 weeks and then sacrificed for morphometric analysis.

Neointimal hyperplasia and late pathologic remodeling in a porcine coronary stent model.

Background: Although coronary stenting has been demonstrated to significantly reduce restenosis compared to conventional angioplasty, occurrence of in-stent stenosis still remains one of the major limitations. This study investigates the influence of stent strut diameter on injury, inflammatory response, thrombosis and neointimal hyperplasia in a porcine coronary artery.

Methods: Coil stents made of either a 0.

M cells and transmural heterogeneity of action potential configuration in myocytes from the left ventricular wall of the pig heart.

Objective: Heterogeneity of action potential configuration in the left ventricle (LV), and the contribution of M cells to it, has been observed in the human heart and is important for arrhythmogenesis. Whether the pig heart has similar properties remains a controversial but important issue as the pig heart is currently under study for use in xenotransplantation.

Methods: Single myocytes were enzymatically isolated from the epicardium (EPI, ncells = 29), midmyocardium (MID, ncells = 38), and endocardium (ENDO, ncells = 13) of the free LV wall (npigs = 26, 14-22 weeks old, 55-80 kg), and studied at different stimulation rates during whole-cell recording (normal Tyrode's solution, K(+)-aspartate-based pipette solution, 50 microM K5fluo-3 as [Ca2+]i indicator, 37 degrees C).

Protein kinase C expression and subcellular distribution in chronic myocardial ischemia. Comparison of two different canine models.

We studied protein kinase C (PKC) isozyme expression and activity distribution in two models of chronically ischemic canine myocardium: (1) single vessel obstruction (SVO), produced by tight stenosis of LAD followed by preconditioning and acute ischemia (40 min); (2) three vessel obstruction (3VO), produced by LAD-stenosis and gradual occlusion of right coronary artery and left circumflex. In both models after 8 weeks of chronic ischemia the dogs were either sacrificed or had PTCA of the LAD with a follow up of another 4 weeks. Control dogs were sham operated.

Repeated stunning precedes myocardial hibernation in progressive multiple coronary artery obstruction.

Objective: The aim of this study was to characterize a regional myocardial flow-function relationship in collateral dependent myocardium produced by multiple coronary artery obstruction.

Methods: Ameroid constrictors were placed around the proximal right (RC) and circumflex (CX) coronary arteries and a silicon tubing cuff around the proximal LAD (left anterior descending artery) (luminal stenosis +/- 77%) in 18 dogs. Weekly two-dimensional echocardiography was performed for regional function (anterior [A], inferoposterior [IP], wall thickening [WT]), and fractional shortening (FS).

In vivo effects of contrast media on coronary thrombolysis.

Objectives: The aim of the present study was to evaluate the influence of radiographic contrast media (CM) on alteplase-induced coronary thrombolysis.

Background: Contrast media inhibit fibrinolysis in vitro and interact with endothelial cells, platelets and the coagulation system. The in vivo effects of CM on thrombolysis are not known.

[Treatment of chronic alcoholic pancreatitis with a new acid-resistant pancreatin product].

The authors summarised pathophysiology and therapy possibility of the chronic alcoholic pancreatitis. They introduce a new product of pancreatin use for treatment of chronic alcoholic pancreatitis. The aim of this prospective study was to asses the efficacy of this new drug in the treatment of chronic alcoholic pancreatitis.