Balloon catheters

Laser ablation systems hold considerable promise if restenosis (reblocking of the arteries) rates are reduced. The rate as of 1995 is 30%, typically within six months. Mechanical or atherectomy devices to cut, shave, or pulverize plaque have been tested extensively in coronary arteries. Some of these have also been approved for peripheral use. The future of angioplasty, beyond the tremendous success of conventional balloon catheters, depends on approaches that can reduce restenosis rates. For example, if appHcation of a dmg to the lesion site turns out to be the solution to restenosis, balloon catheters would be used for both dilating the vessel and deUvering the dmg. An understanding of what happens to the arterial walls, at the cellular level, when these walls are subjected to the various types of angioplasty may need to come first. 

Ca.rdia.c-AssistDevices. The principal cardiac-assist device, the intra-aortic balloon pump (lABP), is used primarily to support patients before or after open-heart surgery, or patients who go into cardiogenic shock. As of the mid-1990s, the lABP was being used more often to stabilize heart attack victims, especially in community hospitals which do not provide open-heart surgery. The procedure consists of a balloon catheter inserted into the aorta which expands and contracts to assist blood flow into the circulatory system and to reduce the heart s workload by about 20%. The disposable balloon is powered by an external pump console. 

FIGURE 4.6 The NeuroFlo device with its dual balloon catheter uniquely designed for partial occlusion of the aorta above and below the origin of the renal arteries. 

The rat carotid artery injured by a balloon catheter has been widely used as a model of angioplasty. The rat model is a proliferation model without foam cells (93). This form of injury causes immediate coagulation and thrombosis cascade in which platelets adhere, spread, and degranulate on the denuded surface of the artery, and approximately 24 hours later SMC begin to proliferate. Liposomal BPs, clodronate, and alendronate were injected to male sabra rats, 15 and 3mg/kg, respectively (52,69,76). Marked neointimal formation and decreased luminal area were observed in control animals. Neointima/media (N/M) ratio was 1.3 0.2, and luminal stenosis was 44 3%. LC and LA suppressed intimal growth when administered intravenously on day -1 and day 6. N/M ratios were reduced by 60% and 69% for LC and LA, respectively. 

Flugelman, M., Jakitsch, M., Newman, K., Casscells, S., Bratthauer, G., and Dichek, D. (1992) In vivo gene transfer into the arterial wall through a perforated balloon catheter. Circulation 85,1110-1117. 

A Swiss physician, Andreas Guentzig, developed the first balloon catheter which was small enough to reach into the coronary arteries. In 1977, he performed the first successful coronary artery dilation treatment. An estimated one million patients per year receive angioplasty as part of their treatment. 

Lactulose may be given as a retention enema via a rectal balloon catheter. Do not use cleansing enemas containing soap suds or other alkaline agents. 

Balloon catheter Border zone Infarcted zone... 

Correlation of in vitro data with human Pefjand Fa% was undertaken with a number of models [25, 27]. Although Fa% data is useful and more broadly available, the introduction of the Loc-I-Gut model by Lennernas allowed direct measurement of PefF. In the Loc-I-Gut model, a segment of the small intestine in humans is isolated using a balloon catheter, disappearance of the drug is measured and the Pgfr can be generated [40]. 

Other than tire use, there are few other significantly large application areas for natural mbber that can be identified, as indicated in Table 10. The use of natural mbber in latex products covers items such as gloves, condoms, balloons, catheters and other dipped goods, latex thread, foam and carpet backing, and rubberized coir and hair. In total, latex goods consume about 11% of world mbber production. Thereafter, there are four categories footwear,... 

PAD, post PTA-DA restenosis Hydrogel-coated balloon catheter after angioplasty VEGF-A Naked DNA Isner, JM. et al. St. Elizabeth s Medical Center, Boston, MA, USA... 

A more advanced catheter is the Dispatch catheter, which is an infusion-perfusion balloon catheter that forms a separate compartment adjacent to target vessel wall when the catheter is inflated (Tahlil et al.,... 

Porous and microporous catheters have also been used for arterial gene delivery. The channeled balloon catheter has 24 longitudinal channels, each containing 100 pm pores, that allows continuous blood... 

Methotrexate Antiproliferative inhibits folate metabolism, purine synthesis and cell proliferation Porcine coronary artery Local application by balloon catheter Did not prevent neointimal thickening (101)... 

Inhibition of restenosis by paclitaxel in the rat carotid arter/ injury model. Paclitaxel inhibits the accumulation of smooth muscle cells 11 days after balloon catheter injury of rat carotid artery. Animals were treated with 2mg/kg body weigh paclitaxel in vehicle (control animals were treated with vehicle alone) two hours after injury and daily for the next four days. 

Several attempts in the past have been made to achieve local gene delivery via coated balloon catheters or infusion catheters using both naked plasmid DNA and adenoviral vectors for the transfer of VEGF-1 or -2 (69,70). Walter et al. (69) demonstrated that local VEGF-2 plasmid gene delivery of a therapeutic gene via coated stents appears feasible, safe, and effective. 

Hiltunen et al, (20) have reported balloon catheter delivery of VEGF-C plasmid after angioplasty injury in vivo. They found a significant reduction in intima-media ratio of the vessels compared with controls. They also studied the effects of VEGF-A plasmid in the same model, but found no benefit. VEGF-D plasmid has also been infused into balloon-injured rabbit aortae. A nitric oxide-dependent significant reduction in intima/media ratio was observed at 14 days (21). 

The time frame of antisense ODN introduction to injured vessel may play an important role in the prevention of restenosis. Schmidt et al. (57) showed that rat carotid artery SMC proliferation begins one to two days after balloon catheter-induced injury, and entry of cells into the growth phase was completed within three days of injury. At the same time, minimally modified b-FGF-specific antisense ODN exerted its antiproliferative activity within this time frame. This strategy has also been successfully applied in the inhibition of various targets, such as c-cbl and c-src (58), HSV-1 (59), and c-myc (47). 

Slow application of 0.2-l.5mL of alcohol through the inflated balloon catheter induces necrosis of the myocardium, which is seen as an obvious contrast enhancement on echocardiography. If the gradient post instillation of alcohol remains above 30 mmHg, the balloon may be positioned more proximally in the vessel or a second septal perforating artery may be treated in the same way,... 

Complications reported with this type of intervention are rare, Rupture of the annulus is reported. The tricuspid valve may also be damaged if a large diameter balloon catheter has been passed inadvertently through the tricuspid valve chordae. After inflation, the balloon is relatively bulky and as it is removed the tricuspid valve apparatus may be disrupted causing regurgitation. A procedure-associated death rate of 0.24% and a major complication rate of 0.35% were found in a large study comprising 822 balloon pulmonary valvuloplasty procedures (15). 

Inoue K, Owaki T, Nakamura T, et al, Clinical application of transvenous mitral commissurotomy by a new balloon catheter. J Thorac Cardiovasc Surg I 984 87(3) 394-402. 

A guidewire and subsequently a balloon catheter (2.0-2.5 mm in diameter) are advanced into the septal perforator. Identification of the target territory is performed by contrast echocardiography to determine the most appropriate septal perforator for ethanol infusion by showing echo... 

Prescott, M. F., Webb, R. L., and Reidy, M. A. 1991. Angiotensin-converting enzyme inhibitor versus angiotensin II, ATI receptor antagonist. Effects on smooth muscle cell migration and proliferation after balloon catheter injury. Am J Pathol 139 1291-1296. 

Kohler, R., Brakemeier, S., Kuhn, M., Behrens, C., Real, R., Degenhardt, C., Orzechowski, H. D., Pries, A. R., Paul, M., and Hoyer, J. 2001. Impaired hyperpolarization in regenerated endothelium after balloon catheter injury. Circ. Res. 89 174-179. 

Zwergel et al. (1991) developed an intact canine model to measure renal pelvic pressure after complete ureteral obstruction with a balloon catheter inflated in the distal ureter. 

Inoue et al. (1990) induced experimental atherosclerosis in the rat carotid artery by balloon de-endothelialization and atherogenic diet. A balloon catheter was introduced into the rat s carotid arteries from the iliac arteries and the endothelium was denuded. 

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