Coronary artery flow

YuXC et al. (2001) Cardiac effects of the extract and active components of Radix stephaniae tetrandrae II. Myocardial infarct, arrhythmias, coronary arterial flow and heart rate in the isolated perfused rat heart. Life Sci 68(25) 2863-2872... 

A 34-year-old man developed palpitation, shortness of breath, and chest pain. He had smoked a quarter to a half an ounce of marijuana per week and had taken it 3 hours before the incident. He had ventricular tachycardia at a rate of 200/minute with a right bundle branch block pattern. Electrical cardioversion restored sinus rhythm. Angiography showed a significant reduction in left anterior descending coronary artery flow rate, which was normalized by intra-arterial verapamil 200 micrograms. 

In the isolated guinea pig auricle protopine caused a prolongation of effective refractory period (42). This action was less intense, but more rapid in onset, than that of allocryptopine. Protopine, 5 X KL moles/kg., prolonged the QRS, PR, and QT segments and increased the height of the T wave. Like allocryptopine, protopine, 2 X 10 moles/kg., sensitized the heart to the fatal ventricular arrhythmias when epinephrine, 1 X 10 moles/kg., was given. Protopine, like papaverine and allocryptopine, caused an increase in coronary artery flow. 

Although primary PCI restores normal epicardial coronary artery flow in >90% of patients with acute myocardial infarction, a large number... 

An aromatized alkaloid of this derivation, papaverine (31) is the most important alkaloid of the BIQ group from the pharmacological point of view. Papaverine inhibits aldol reductase, GABA and glucose response in chemosensory cells, and phosphodiesterase (Wink, 1993). In vivo, this alkaloid decreases the tonus of the smooth muscle, increases coronary artery flow, and causes dilation. Papaverine has a beneficial effect on angina pectoris. This aromatic isoquinoline alkaloid is neither narcotic nor addictive (Cordell, 1981). Papaverine has an LD50 i.v. in mouse of 27.5 mg/kg. Demethylpa-paverine inhibits aldose reductase (Wink, 1993). 

Small arterial prostheses Replacement of deficient coronary arteries Flowing blood high shear rate high ratio of contacted surface/blood volume Currently none... 

In addition to its internal blood flow operation, the heart has its own system of blood vessels to keep the muscle wall of the heart, the myocardium, supphed with oxygenated blood (Fig. 3a). The coronary arteries, which branch from the aorta to the right and left sides of the heart, are vital to maintaining that supply. The heart is an extraordinary electromechanical muscle that can be trained to increase blood flow to the body sixfold. It can range from 5 to 30 L /min during exertion. 

We hear a lot these days about the relationships between saturated fats, cholesterol, and heart disease. What are the facts It s well established that a diet rich in saturated animal fats often leads to an increase in blood serum cholesterol, particularly in sedentary, overweight people. Conversely, a diet-lower in saturated fats and higher in polyunsaturated fats leads to a lower serum cholesterol level. Studies have shown that a serum cholesterol level greater than 240 mg/dL (a desirable value is <200 mg/dL) is correlated with an increased incidence of coronary artery disease, in which cholesterol deposits build up on the inner walls of coronary arteries, blocking the flow of blood to the heart muscles. 

Acute coronary syndromes most often result from a physical disruption of the fibrous cap, either frank cap fracture or superficial endothelial erosion, allowing the blood to make contact with the thrombogenic material in the lipid core or the subendothelial region of the intima. This contact initiates the formation of a thrombus, which can lead to a sudden and dramatic blockade of blood flow through the affected artery. If the thrombus is nonocclusive or transient, it may either be clinically silent or manifest as symptoms characteristic of unstable angina. Importantly, if collateral vessels have previously formed, for example, due to chronic ischemia produced by multi vessel disease, even total occlusion of one coronary artery may not lead to an acute myocardial infarction. 

Ischemic heart disease (IHD) is also called coronary heart disease (CHD) or coronary artery disease. The term ischemic refers to a decreased supply of oxygenated blood, in this case to the heart muscle. Ischemic heart disease is caused by the narrowing of one or more of the major coronary arteries that supply blood to the heart, most commonly by atherosclerotic plaques. Atherosclerotic plaques may impede coronary blood flow to the extent that cardiac tissue distal to the site of the coronary artery narrowing is deprived of sufficient oxygen in the face of increased oxygen demand. Ischemic heart disease results from... 

Acute coronary syndromes is a term that includes all clinical syndromes compatible with acute myocardial ischemia resulting from an imbalance between myocardial oxygen demand and supply.3 In contrast to stable angina, an ACS results primarily from diminished myocardial blood flow secondary to an occlusive or partially occlusive coronary artery thrombus. Acute coronary syndromes are classified according to electrocardiogram (ECG) changes into STE ACS (STE MI) or NSTE ACS (NSTE MI and unstable angina) (Fig. 5-1). An STE MI, formerly... 

Short-term desired outcomes in a patient with ACS are (1) early restoration of blood flow to the infarct-related artery to prevent infarct expansion (in the case of MI) or prevent complete occlusion and MI (in unstable angina) (2) prevention of death and other complications (3) prevention of coronary artery reocclusion and (4) relief of ischemic chest discomfort. 

Coronary artery bypass graft surgery Thoracic surgery whereby parts of a saphenous vein from a leg or internal mammary artery from the arm are placed as conduits to restore blood flow between the aorta and one or more coronary arteries to bypass the coronary artery stenosis (occlusion). 

Percutaneous coronary intervention A minimally invasive procedure whereby access to the coronary arteries is obtained through the femoral artery up the aorta to the coronary os. Contrast media is used to visualize the coronary artery stenosis using a coronary angiogram. A guidewire is used to cross the stenosis and a small balloon is inflated and/or stent is deployed to break up atherosclerotic plaque and restore coronary artery blood flow. The stent is left in place to prevent acute closure and restenosis of the coronary artery. Newer stents are coated with antiproliferative drugs, such as paclitaxel and sirolimus, which further reduce the risk of restenosis of the coronary artery. 

The answer is a. (Hardman, pp 762-764.) Experimentally, nitrates dilate coronary vessels. This occurs in normal subjects, resulting in an overall increase in coronary blood flow. In arteriosclerotic coronaries, the ability to dilate is lost, and the ischemic area may actually have less blood flow under the influence of nitrates. Improvement in the ischemic conditions is the result of decreased myocardial oxygen demand because of a reduction of preload and afterload. Nitrates dilate both arteries and veins and thereby reduce the work of the heart. Should systemic blood pressure fall, a reflex tachycardia will occur. In pure coronary spasm, such as Prinzmetal s angina, the effect of increased coronary blood flow is relevant, while in severe left ventricular hypertrophy with minimal obstruction, the effect on preload and afterload becomes important. 

In contrast to stable angina, an ACS results primarily from diminished myocardial blood flow secondary to an occlusive or partially occlusive coronary artery thrombus. 

NTG causes venodilation, which lowers preload and myocardial oxygen demand. In addition, arterial vasodilation may lower BP, thereby reducing myocardial oxygen demand. Arterial dilation also relieves coronary artery vasospasm and improves myocardial blood flow and oxygenation. 

Dopamine produces dose-dependent hemodynamic effects because of its relative affinity for cq-, /Jr, /J2-, and Dr (vascular dopaminergic) receptors. Positive inotropic effects mediated primarily by / -receptors become more prominent with doses of 2 to 5 mcg/kg/min. At doses between 5 to 10 mcg/kg/min, chronotropic and -mediated vasoconstricting effects become more prominent. Especially at higher doses, dopamine alters several parameters that increase myocardial oxygen demand and potentially decrease myocardial blood flow, worsening ischemia in some patients with coronary artery disease. 

PAD is a coronary artery disease risk equivalent, andaBPgoaloflower-extremity PAD CCBs may also be beneficial. /3-Blockers have traditionally been considered problematic because of possible decreased peripheral blood flow secondary to unopposed stimulation of a-receptors that results in vasoconstriction. However, /3-blockers are not contraindicated in PAD and have not been shown to adversely affect walking capability. 

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