Coronary artery stenosis

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. 

High-risk NSTE ACS patients should undergo early coronary angiography (within 24 to 48 hours) and revascularization if a significant coronary artery stenosis is found. Moderate-risk patients with positive biochemical... 

The action of nitrates appears to be mediated indirectly through reduction of MVo2 secondary to venodilation and arterial-arteriolar dilation, leading to a reduction in wall stress from reduced ventricular volume and pressure. Direct actions on the coronary circulation include dilation of large and small intramural coronary arteries, collateral dilation, coronary artery stenosis dilation, abolition of normal tone in narrowed vessels, and relief of spasm. 

Flow through moderately severe coronary artery stenosis is commonly normal at rest but becomes inadequate for the increased metabolic requirements and blood flow during stress. Coronary blood flow normally increases to four times resting baseline flow rates after coronary artery vasodilators such as dipyridamole and adenosine. A stenosis restricts maximal blood flow capacity compared to normal coronary arteries, thereby causing a disparity in regional perfusion of areas supplied by a stenotic artery compared to normal coronary arteries. This disparity manifests as a relative perfusion defect during stress, corresponding to the ischemic myocardial territory supplied by a stenotic artery. Furthermore, the quantitative severity of the relative perfusion defect is proportional to the severity of the stenosis under conditions of maximal coronary flow after dipyridamole or adenosine stress [24]. 

Gould KL. Assessing myocardial viability. In Gould KL. Coronary artery stenosis and reversing atherosclerosis. 2nd ed. London Arnold, pp 329-357, 1999... 

Gould KL. Quantification of coronary artery stenosis in vivo. Circ Res 1985 57 341-353... 

Greuntzig AR, Turina MI, Schneider JA. Experimental percutaneous dilatation of coronary artery stenosis. Circulation 1976 54 81. 

I. Madar, H. Ravert, A. Dipaula, Y. Du, R.F. Dannals, L. Becker, Assessment of severity of coronary artery stenosis in a canine model using the PET agent F-fluorobenzyl triphenyl phosphonium Comparison with " Tc-tetrofosmin, J. Nucl. Med. 48 (2007) 1021-1030. 

A 61-year-old man with coronary artery stenosis became hypotensive during elective surgery, refractory to ephedrine (cumulative dose of 36 mg over 45 minutes). Immediately after terlipressin 1 mg, he developed hypertension and bradycardia, with evidence of myocardial ischemia. 

Voudris V Alexopoulos E, Karyofillis R et al. Prospective native coronary artery stenosis treated with sirolimus-eluting stent (ONASSIS) registry—acute results and mid-term outcomes a single-center experience. J Invasive Cardiol 2005 17(8)401-405. 

P. Golino, M. Buja, Y. Shcng-Kun, J. McNatt and J. T. Willerson, Failure of nitroglycerin and diltiazem to reduce platelet-mediated vasoconstriction in dogs with coronary artery stenosis and endothelial injury further evidence for thromboxane A2 and serotonin as mediators of coronary artery vasoconstriction in vivo, J Am Coll Cardiol 15, 718-726 (1990). 

P. R. Kowey, R. L. Verrier, B. Lown and R. I. Handin, Influence of intracoronary platelet aggregation on ventricular electrical properties during partial coronary artery stenosis, Am J Cardiol 51, 596-602 (1983). 

Sclarovsky S, Nikus KC, Birnbaum Y. Manifestation of left main coronary artery stenosis is diffuse ST depression in inferior and precordial leads on ECG. J Am Coll Cardiol 2002 40 575. 

There has been concern that overtreating high BP in patients with coronary artery disease may bring about more harm than good (termed the J-curve phenomenon). Since coronary blood flow occurs during diastole, the rate of flow is directly influenced by the DBP. Therefore, excessively reducing DBP may compromise coronary perfusion, especially in patients with fixed coronary artery stenosis, and lead to myocardial infarction. This concern has been theoretical based on retrospective analyses, and prospective studies have not found a J-curve until DBPs were very low (<60 mm Hg). However, this controversy has resurfaced because a post-hoc subgroup analysis of the INVEST study has shown a J-curve in patients with DBP less than 84 mm Hg. 

Diastolic murmur (in absence of aortic regurgitation) Coronary artery stenosis Rare... 

Taggart S, Kaul W, Boden WE, et al. Revascularization for unprotected left main stem coronary artery stenosis stenting or surgery. J Am Coll Cardiol 2008 51(9) 885-92. 

Palmerini T, Marzocchi A, Marrozzini C, et al. Comparison between coronary angioplasty and coronary bypass surgery for the treatment of unprotected left main coronary artery stenosis (the Bologna registry). Am J Cardiol 2006 98 54-9. 

Austin, G.E., Ratcliff, N.B., Hollman, J., Tobei, S. and Phillipis, D.F. (1985). Intimal proliferation of smooth muscle cells as an explanation for recurrent coronary artery stenosis after percutaneous transluminal coronary angioplasty. ]. Am. Coll Cardiol, 6, 369-375... 

Gruntzig AR, Senning A, Siegenthaler WE. Nonoperative dilatation of coronary-artery stenosis Percutaneous transluminal coronary angioplasty. N. Engl. J. Med. 1979 301 61-68. 

Fig. 15.3. After segmentation of the coronary arteries, dedicated software allows for quantifying the degree of coronary artery stenosis. The reliability of this measurement as compared to quantitative coronary assessment (QCA) by cardiac catheter has not yet been determined...

Garcia M J, Lessick J, Hoffmann MH (2006) Accuracy of 16-row multidetector computed tomography for the assessment of coronary artery stenosis. JAMA 296 403-411... 

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