RCIS key terms

The ratio of maximum blood flow through a stenotic coronary artery to maximum flow if that artery were normal, calculated from pressure measurements taken distal and proximal to the lesion during hyperemia. A value at or below 0.80 generally indicates a hemodynamically significant stenosis.

A pressure-derived index of coronary stenosis severity measured during a specific diastolic period when microvascular resistance is naturally low and stable, so no vasodilator drug is required. Like FFR, it compares distal coronary pressure with aortic pressure.

A short-acting vasodilator given intravenously or intracoronary to produce maximal coronary hyperemia for pressure-wire studies. It can cause flushing, chest discomfort, bronchospasm, and transient heart block, so it is used cautiously in reactive airway disease.

A drug-induced state of maximal coronary blood flow in which the small resistance vessels are fully dilated. It is required for FFR measurement because it minimizes microvascular resistance so that pressure differences reflect the epicardial stenosis.

The volume of blood pumped by the heart per minute, calculated as oxygen consumption divided by the arteriovenous oxygen content difference. It can be measured directly by thermodilution or estimated from the Fick principle using measured oxygen saturations.

Cardiac output normalized to body surface area, expressed in liters per minute per square meter. It allows comparison of flow between patients of different sizes; a typical resting value is roughly 2.5 to 4.0 L/min/m².

The resistance offered by the systemic circulation to blood flow, derived from mean arterial pressure minus right atrial pressure, divided by cardiac output. Elevated values suggest vasoconstriction or low flow, while low values suggest vasodilation or distributive shock.

The resistance to blood flow across the pulmonary circulation, calculated from the mean pulmonary artery pressure minus pulmonary capillary wedge pressure, divided by cardiac output. It helps distinguish precapillary from postcapillary causes of pulmonary hypertension.

An estimate of left atrial pressure obtained by inflating the balloon on a pulmonary artery catheter and recording the pressure distal to the occlusion. It is used to assess left ventricular filling and to separate cardiogenic from noncardiogenic pulmonary edema.

A method of measuring cardiac output by injecting a known volume of cool or room-temperature fluid into the right atrium and recording the temperature change downstream in the pulmonary artery. The area under the resulting temperature curve is inversely related to flow.

A balloon-tipped, flow-directed catheter passed through the right heart into the pulmonary artery to measure right-sided and wedge pressures, cardiac output, and mixed venous oxygen saturation. It is also called a Swan-Ganz catheter.

The oxygen saturation of blood in the pulmonary artery, reflecting the balance between whole-body oxygen delivery and oxygen consumption. A low value suggests inadequate delivery or increased demand, while a high value may indicate impaired tissue extraction.

The average arterial pressure during a cardiac cycle, approximately one-third of the pulse pressure added to the diastolic pressure. It is the driving pressure for organ perfusion and is used in resistance and hemodynamic calculations.

A venous channel on the posterior heart that collects most of the cardiac venous drainage and empties into the right atrium near the inferior vena cava. It is a landmark for catheter placement and for retrograde cardioplegia delivery.

The short common trunk arising from the left aortic sinus that promptly divides into the left anterior descending and circumflex arteries. Significant disease here threatens a large portion of the left ventricle and carries high risk during catheterization.

A major coronary branch that runs down the anterior interventricular groove, supplying the anterior left ventricle and much of the septum. Its proximal occlusion can cause extensive infarction and is sometimes called the widow-maker lesion.

An invasive imaging procedure in which contrast is injected into the coronary arteries through a catheter to visualize their anatomy and identify stenoses. It is the reference standard for defining coronary artery disease before intervention.

Continuous x-ray imaging displayed on a monitor that allows real-time guidance of catheters, wires, and contrast injections during invasive procedures. Stored cine runs permit later review of angiographic findings.

Iodine-based solutions injected into vessels to make them radiopaque during angiography and fluoroscopy. They can cause allergic reactions and kidney injury, so hydration and allergy history review are important before use.

An acute decline in kidney function occurring within days after iodinated contrast administration, after other causes are excluded. Risk is higher with preexisting kidney disease, diabetes, low ejection fraction, and large contrast volumes.

The amount of ionizing radiation energy absorbed by tissue during a procedure, influenced by fluoroscopy time, magnification, and patient size. Keeping dose as low as reasonably achievable protects both patients and staff.

A radiation safety concept meaning doses should be kept as low as reasonably achievable while still obtaining the needed diagnostic information. It guides choices such as minimizing fluoroscopy time and using pulsed imaging.

A garment containing lead or other dense material worn by staff during fluoroscopic procedures to shield the body from scattered radiation. Proper fit, storage without folding, and periodic inspection maintain its protective value.

A technique of entering the arterial system through the wrist rather than the femoral artery, often reducing bleeding complications and allowing earlier ambulation. It requires attention to ulnar collateral flow and spasm prevention.

A common route for cardiac catheterization in which the common femoral artery is punctured below the inguinal ligament. Careful landmarking and sheath management reduce risks of bleeding, hematoma, and retroperitoneal hemorrhage.

Bleeding into the space behind the abdominal cavity, often after a high femoral puncture above the inguinal ligament. It may present with back or flank pain, hypotension, and falling hematocrit without visible groin swelling.

A narrowing of the radial artery during catheter manipulation that can impede catheter movement and cause pain. It is managed with gentle technique, adequate sedation, and intra-arterial vasodilators such as nitroglycerin or verapamil.

A catheter technique in which the operator advances from a distal vessel or chamber backward toward the target, such as passing a catheter against the direction of flow. It contrasts with antegrade advancement along normal flow.

A catheter technique in which the operator advances the catheter in the direction of normal blood flow toward the target structure or vessel. It is the standard direction for most coronary and valvular interventions.

A procedure in which a needle and catheter are passed from the right atrium through the interatrial septum into the left atrium. It provides access for left-sided structural interventions such as mitral valvuloplasty or left atrial appendage closure.

A shallow depression on the right atrial side of the interatrial septum marking the site of the fetal foramen ovale. It is the preferred target for transseptal puncture because the septum is thin there.

The upper left chamber that receives oxygenated blood from the pulmonary veins and empties through the mitral valve into the left ventricle. Its pressure and size are commonly assessed during hemodynamic and structural procedures.

The upper right chamber that receives systemic venous return from the superior and inferior venae cavae and coronary sinus, then delivers blood through the tricuspid valve. Its pressure reflects right-sided filling and volume status.

Needle drainage of fluid from the pericardial sac, usually guided by echocardiography and fluoroscopy. It is performed for cardiac tamponade or to obtain fluid for diagnosis, and carries risk of myocardial puncture and arrhythmia.

A life-threatening condition in which pericardial fluid raises pressure around the heart and impairs ventricular filling. Signs include hypotension, elevated jugular venous pressure, muffled heart sounds, and pulsus paradoxus.

An exaggerated drop in systolic blood pressure during inspiration, typically greater than 10 mm Hg. It reflects impaired right ventricular filling and is classically associated with cardiac tamponade and severe asthma.

An estimate of total body surface calculated from height and weight, used to normalize physiologic measurements such as cardiac output and drug dosing. Most hemodynamic index values in the catheterization laboratory are based on it.