Coronary artery dilation using

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. 

Percutaneous coronary intervention (PCI) is one of a host of techniques performed by using a catheter inserted via a major limb artery that aims to relieve nanowing of coronary arteries. For example, percutaneous transluminal coronary angioplasty (PTCA) is the classic PCI that uses a catheter-directed balloon to dilate a stenotic coronary artery, and more recent PCIs include stent implantation, rotational atherectomy, and laser angioplasty. 

Methyixanthines relax smooth muscle, and have a bronchodilating effect in the lungs. Theophylline is used as a treatment for asthma. Methyixanthines dilate coronary arteries, increasing cardiac blood flow, but an opposite effect occurs on cerebral blood vessels (see below). 

Papaverine is an opium alkaloid initially isolated in the mid-1800s. It relaxes smooth muscle and is a potent vasodilator. As such it is used to dilate pulmonary and other arteries. It is therefore sometimes of use in the treatment of angina pectoris (usually caused by partial blockage of the coronary artery), heart attacks and bronchial spasms. 

Mechanism of Action A potent vasodilator used to treat emergent hypertensive conditions acts directly on arterial and venous smooth muscle. Decreases peripheral vascular resistance, preload and afterload improves cardiac output. Therapeutic Effect Dilates coronary arteries, decreases oxygen consumption, and relieves persistent chest pain. 

ACE). Hence, angiotensin II production is inhibited. Decrease in angiotensin II results in dilatation of peripheral vessels leading to a reduction in systemic vascular resistance and a decreased aldosterone secretion. They can be administered safely in patients of hypertension with diabetes mellitus or bronchial asthma. ACE inhibitors are efficacious drugs, are well tolerated and are useful antihypertensive drugs. ACE inhibitors are also used in coronary artery... 

Q13 Calcium channel blockers decrease the opening of L-type calcium channels in the plasma membrane of vascular smooth muscle cells, and so reduce intracellular calcium concentration and contractile activity. The blood vessels therefore dilate. Calcium channel blockers act mainly on the arterial side of the circulation, and the dihydropyridines, such as nifedipine, are useful coronary arteriolar dilator agents. These agents are usually the treatment of choice for Prinzmetal angina. 

Cardiovascular effects include tachycardia, hypertension, and increased cardiac irritability large intravenous doses can cause cardiac failure. Cardiac dysrhythmias have been ascribed to a direct toxic effect of cocaine and a secondary sensitization of ventricular tissue to catecholamines (17), along with slowed cardiac conduction secondary to local anesthetic effects. Myocardial infarction has increased as a complication of cocaine abuse (7,8). Dilated cardiomyopathies, with subsequent recurrent myocardial infarction, have been associated with long-term use of cocaine, raising the possibility of chronic effects on the heart (18). Many victims have evidence of pre-existing fixed coronary artery disease precipitated by cocaine (SEDA-9, 35) (19-21). However, myocardial infarction has been noted even in young intranasal users with no evidence of coronary disease (22), defined by autopsy or angiography (23,24). If applied to mucous membranes, cocaine causes local vasoconstriction, and, with chronic use, necrosis. 

Four categories of calcium channel blockers can be defined based on their chemical structures and actions diphenylalkylamines, benzothiazepines, dihydropyridines, and bepridil. Both diphenylalkylamines (verapamil) and benzothiazepines (diltiazem) exhibit effects on both cardiac and vascular tissue. With specificity for the heart tissue, these two types of calcium channel blockers can slow conduction through the AV node and are useful in treating arrhythmias. The dihydropyridines (nifedipine is the prototypical agent) are more potent peripheral and coronary artery vasodilators. They do not affect cardiac conduction, but can dilate coronary arteries. They are particularly useful as antianginal agents. Bepridil is unique in that it blocks both fast sodium channels and calcium channels in the heart. All calcium channel blockers, except nimodipine and bepridil, are effective in treating HTN. 

Pharmacological investigations using a particular valepotriate fraction called Vpt2 extracted from the roots of V. officinalis (L.) have shown antiar-rhythmic activity and ability to dilate coronary arteries in experimental animals. Moderate positive inotropic and a negative chronotropic effect were also observed. Vpt2 contains valtratum (50%), valeridine (25%), and valechlorin (3%), with trace amounts of acevaltrate, dihydrovaltratum, and epi-7-desacetyl-isovaltrate (36). 

Diltiazem hydrochloride is a calcium ion influx inhibitor (slow channel blocker or calcium antagonist). It has generally been indicated for the treatment of angina and, more recently (2), hypertension. Diltiazem hydrochloride is a potent dilator of coronary arteries and has been shown to increase exercise tolerance in man. It is available for dosing as immediate release tablets and as extended or sustained release capsules and is usually well-tolerated. While some adverse reactions have been reported during diltiazem hydrochloride therapy, it is generally considered to be well-tolerated. In most cases, no causal relationship between the events and diltiazem hydrochloride use has yet to be established (1). 

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