![]() There is a definite ,sudden pressure drop distal to the obstruction. What determines the post stenotic dilatation ? Coronary ectasia is also a possibility but since it is related to site of obstruction the former is likely. Here is a patient with a tight LAD lesion with a significantly dilated segment located immediately beyond the obstruction.This can be considered as a post stenotic dilatation. It is more common in large vessels than small ones. It may not be linked to newtons law but it is observed in many. In vascular hemodynamics whenever there is a an obstruction, there tend to be a dilatation of the same blood vessel somewhere distally. Newtons third law of motion says for every action there is an equal and opposite reaction. Let me post our experience during PCI shortly. I feel so, but my colleague Dr Gnanavelu strongly differs ! (We can’t get a stent just like that unless it is a real emergency. He is posted for elective PCI this week-end. Since he had significant angina there were no debates regarding management. **Note further : This hemodynamic principle may not apply in acute occlusion as in STEMI, where acute obstruction often has a linear relationship with the quantum of blood flow.īy the way what happened to the above patient ? * The garden hose analogy is a gross simplification of complex factors that determine coronary blood flow.But it effectively clarifies a point ie coronary blood flow is least dependent on coronary stenosis (until very late stages) This is based on Bernoulli principle and is akin to how a garden hose pipe can simply increase the velocity by tightening the nozzle.* The distal vascular bed drops its resistance drastically once it senses the problem in proximal segment. Realise there is no simple relation between the degree of obstruction and degree of blood flow impediment.It can be linear, curvilinear, or even inverse depending upon the evolution and timing of obstruction, number of lesions, presence or absence of collateral support, finally and most importantly the integrity of microvascular bed. This is what is happening to this man with a stable angina and perfectly normal micro vascular bed.ĭo not get fooled by the lay man’s logic. If it is normal even a hair-line patency can profusely perfuse the distal myocardial segment. The distal flow beyond an obstruction is not primarily dependent on degree of obstruction but the status of the distal vascular bed. An almost invisible antegrade channel doing a exemplary job ! Or is it a very efficient instant collaterals from LCX ?.Can a trickle of ante grade flow sustain a TIMI 3 FLOW ?.TIMI 2 flow (partial reperfusion) is delayed or sluggish antegrade flow with complete filling of the distal territory.TIMI 1 flow (penetration without perfusion) is faint antegrade coronary flow beyond the occlusion, with incomplete filling of the distal coronary bed.TIMI 0 flow (no perfusion) refers to the absence of any antegrade flow beyond a coronary occlusion.'TIMI Grade Flow' is a scoring system from 0-3 referring to levels of coronary blood flow assessed during percutaneous coronary angioplasty: TIMI risk can be calculated on the TIMI website under "Clinical Calculators." 'TIMI risk' estimates mortality following acute coronary syndromes. % risk at 14 days of: all-cause mortality, new or recurrent MI, or severe recurrent ischemia requiring urgent revascularization. ST changes of at least 0.5mm on admission EKG At least 2 angina episodes within the last 24hrs Or female first-degree relative or mother less than 65). (CAD in male first-degree relative, or father less than 55, Such as: Hypertension -> 140/90 or on antihypertensives, Known Coronary Artery Disease (CAD) (coronary stenosis >= 50%) Aspirin use in the last 7 days (patient experiences chest pain despite ASA use in past 7days) TIMI Score Calculation (1 point for each): It is used to categorize a patient's risk of death and ischemic events and provides a basis for therapeutic decision making. The TIMI Risk Score is used in patients with U nstable Angina / Non-ST Elevation Myocardial Infarction. It has conducted numerous practice-changing clinical trials in patients with cardiovascular disease or risk factors for cardiovascular disease TIMI stands for ' Thrombolysis In Myocardial Infarction' and is the name of an Academic Research Organization (ARO) which was founded by Dr. ![]()
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