ABIM Interventional Cardiology key terms

The ratio of maximal coronary blood flow in a stenotic artery to maximal flow if that artery were normal, calculated from distal coronary pressure divided by aortic pressure during hyperemia. Values at or below 0.80 generally identify ischemia-producing lesions warranting revascularization.

A non-hyperemic pressure ratio measured during the wave-free period of diastole, when microvascular resistance is naturally low and stable. A value of 0.89 or less is typically considered hemodynamically significant.

A pharmacologic agent such as intravenous or intracoronary adenosine that dilates the microcirculation to maximize coronary flow, removing autoregulation so pressure ratios reflect stenosis severity. Required for FFR but not for resting indices like iFR.

The ratio of hyperemic to resting coronary blood flow velocity, reflecting the combined capacity of epicardial conductance and microvascular function. A reduced value can indicate either an epicardial stenosis or microvascular dysfunction.

Impaired vasodilator capacity or increased resistance of the small coronary vessels, producing angina or ischemia despite angiographically unobstructed epicardial arteries. Assessed with indices such as the index of microcirculatory resistance.

A thermodilution-derived measure of minimal microvascular resistance calculated from distal pressure and hyperemic transit time. Elevated values suggest microvascular disease and predict worse outcomes after infarction or PCI.

Catheter-based grayscale imaging using high-frequency sound to display vessel wall and plaque cross-sections. Used to guide stent sizing, assess plaque burden, and confirm adequate stent expansion and apposition.

Intracoronary imaging using near-infrared light to produce high-resolution cross-sections of the vessel lumen and wall. Excels at detailing plaque morphology, thrombus, dissection, and stent strut coverage.

Computer-assisted measurement of coronary dimensions and percent diameter stenosis from angiographic frames. Provides objective lesion quantification for research and for planning intervention.

The percent reduction in luminal diameter at a lesion relative to an adjacent normal reference segment. Angiographic severity alone correlates poorly with physiologic significance.

A coronary stent coated with antiproliferative drug within a polymer or on its surface, released locally to suppress neointimal hyperplasia. Reduced restenosis compared with bare-metal stents and is the default device for most PCI.

Renarrowing within a previously stented segment from neointimal tissue growth or, with drug-eluting stents, often neoatherosclerosis. Presents as recurrent ischemia and is treated with drug-coated balloons, repeat stenting, or debulking.

Incomplete expansion of a stent relative to the reference vessel, usually from inadequate balloon sizing or calcified plaque. A major predictor of restenosis and stent thrombosis, best detected by intravascular imaging.

Incomplete contact between stent struts and the vessel wall, leaving a gap. Acute malapposition may result from undersizing; late-acquired malapposition is associated with stent thrombosis.

Thrombotic occlusion or mural thrombus within a stented segment, classified as acute, subacute, late, or very late by timing. Often catastrophic and linked to premature antiplatelet cessation, malapposition, or underexpansion.

Combined aspirin plus a P2Y12 inhibitor used to prevent thrombotic events after stenting and in acute coronary syndromes. Duration is individualized by bleeding and ischemic risk.

An oral antiplatelet drug blocking the ADP receptor on platelets, including clopidogrel, prasugrel, and ticagrelor. Combined with aspirin after PCI; potency and metabolism differ among agents.

Persistently elevated platelet aggregation despite antiplatelet therapy, most often with clopidogrel due to impaired CYP2C19 activation. Associated with increased thrombotic risk and sometimes used to guide escalation.

An intravenous agent blocking the platelet fibrinogen receptor, preventing final aggregation. Used adjunctively in high-risk PCI or thrombotic complications such as no-reflow.

A direct thrombin inhibitor used as an alternative to heparin during PCI. Short-acting with predictable kinetics; historically associated with less bleeding but more acute stent thrombosis than heparin plus glycoprotein inhibition.

Acute myocardial infarction with persistent ST elevation on ECG reflecting complete coronary occlusion. Requires emergent reperfusion, preferably primary PCI, to limit infarct size.

Emergent percutaneous coronary intervention as the preferred reperfusion strategy for STEMI, ideally within 90 minutes of first medical contact. Achieves higher patency and lower bleeding than fibrinolysis when delivered promptly.

The interval from hospital arrival to first device activation in the infarct artery during primary PCI. A quality metric, with a target of 90 minutes or less.

The coronary plaque responsible for the acute ischemic syndrome, typically identified by angiographic thrombus, occlusion, or ECG territory. Revascularization is directed at this lesion in the acute setting.

Failure to achieve normal myocardial perfusion despite an open epicardial artery, from microvascular obstruction and embolization. Manifests as slow flow or myocardial blush and is managed with vasodilators and aspiration.

Non-traumatic separation of coronary wall layers causing luminal narrowing or occlusion, often in younger women without atherosclerotic risk factors. Conservative management is preferred in stable cases.

Full-thickness injury of the coronary artery during PCI causing contrast or blood extravasation. Classified by severity and treated with balloon tamponade and covered stents or embolization.

A stent with a fabric or graft layer that seals vessel wall defects. Used to treat coronary perforation or large aneurysms when balloon tamponade alone fails.

Accumulation of pericardial fluid under pressure that impairs ventricular filling and causes obstructive shock. A feared consequence of coronary perforation, recognized by hypotension and echocardiographic findings.

Needle drainage of pericardial fluid, used emergently to relieve tamponade. Performed under echocardiographic or fluoroscopic guidance, often with catheter left in place.

Acute decline in renal function within days of iodinated contrast administration, attributed to renal vasoconstriction and direct tubular toxicity. Prevented by minimizing contrast volume and ensuring hydration.

The total amount of iodinated contrast administered during a procedure. A modifiable determinant of kidney injury and a key metric in complex or multivessel interventions.

The quantity of ionizing radiation absorbed during fluoroscopically guided procedures, tracked via dose-area product and air kerma. Minimized through low frame rates, collimation, and distance.

Total duration of X-ray exposure during a procedure, a surrogate for radiation dose to patient and operator. Reduced by efficient technique and pulsed fluoroscopy.

Techniques to reduce access-site and systemic bleeding, including radial access, smaller sheaths, careful anticoagulation dosing, and closure devices. Lower bleeding improves outcomes after PCI.

Cannulation of the radial artery for catheter procedures, preferred over femoral access for lower bleeding and earlier ambulation. Requires assessment of collateral ulnar flow and awareness of spasm.

Painful constriction of the radial artery during catheter manipulation, impeding device passage. Prevented with vasodilator cocktails and gentle technique.

Bleeding into the retroperitoneal space, usually after high femoral arterial puncture. Presents with flank pain, hypotension, and falling hematocrit; managed with resuscitation and sometimes embolization.

Narrowing of the aortic valve obstructing left ventricular outflow, causing pressure overload and symptoms of angina, syncope, or heart failure. Severe symptomatic disease warrants valve replacement.

Implantation of a prosthetic aortic valve via catheter, typically through the femoral artery, without sternotomy. An alternative to surgery across a widening spectrum of surgical risk.

Regurgitation around the outside of an implanted prosthetic valve. After TAVR it is associated with worse outcomes and is assessed by echocardiography and angiography.

Balloon dilation of a stenotic aortic valve to increase orifice area. Provides temporary symptom relief as a bridge or palliation; rarely definitive.

Backflow of blood from left ventricle to left atrium due to valve leaflet or annular pathology. Severe symptomatic disease may be treated surgically or with transcatheter edge-to-edge repair.

Catheter-delivered clip approximation of mitral leaflets to reduce regurgitation in selected patients. An option for high surgical risk with favorable anatomy.

Pressure within the left atrium, estimated invasively as pulmonary capillary wedge pressure. Guides management of heart failure and assessment during structural interventions.

Volume of blood ejected by the heart per minute, equal to stroke volume times heart rate. Measured by thermodilution or Fick methods to assess hemodynamic status.

Cardiac output normalized to body surface area. Used to classify shock states and guide therapy in the catheterization laboratory.

Atherosclerotic narrowing of non-coronary arteries, most commonly the lower extremities, causing claudication or critical limb ischemia. Managed with risk-factor modification and revascularization when indicated.

Ratio of ankle to brachial systolic pressure used to screen for and grade lower-extremity arterial disease. Values below 0.90 suggest stenosis; very high values suggest non-compressible vessels.

A balloon catheter that delivers antiproliferative drug to the vessel wall during dilation without leaving a permanent implant. Used in peripheral and coronary in-stent restenosis.

A contained arterial rupture communicating with the lumen through a neck, often at an access site. Treated with ultrasound-guided compression or thrombin injection.