Plain-language definitions of terms used across CardioLearn. Each links back to the fuller page where the term is explained in context.

  • Ablation (Catheter Ablation) — a procedure that uses heat or cold delivered through a catheter to disable a specific piece of tissue causing an abnormal heart rhythm. See Atrial Fibrillation.
  • ACE Inhibitor — a medication that relaxes blood vessels and reduces strain on the heart; one option in the "four pillars" of HFrEF treatment. See Medications 101.
  • AFib (Atrial Fibrillation) — a heart rhythm disorder where the upper chambers quiver instead of beating in a coordinated way, raising stroke risk. See Atrial Fibrillation.
  • Amyloidosis (Cardiac) — a disease where abnormal protein deposits stiffen the heart muscle. See Cardiac Amyloidosis.
  • Angina — chest discomfort caused by reduced blood flow to the heart muscle, often a symptom of coronary artery disease.
  • Anticoagulant — a "blood thinner" medication that reduces clotting, commonly used to prevent stroke in AFib. See Medications 101.
  • Antiplatelet — a medication that prevents blood platelets from clumping together, commonly used after a stent or heart attack.
  • ARB (Angiotensin Receptor Blocker) — a blood-pressure-lowering medication with a similar effect to an ACE inhibitor, often used when ACE inhibitors aren't tolerated.
  • ARNI — a combination medication that's often the preferred "pillar" of HFrEF treatment over a standalone ACE inhibitor/ARB.
  • Apnea-Hypopnea Index (AHI) — the number of breathing pauses per hour measured during a sleep study, used to grade sleep apnea severity. See Sleep Apnea & Heart Disease.
  • Arrhythmia — any abnormal heart rhythm, whether too fast, too slow, or irregular.
  • ARVC (Arrhythmogenic Right Ventricular Cardiomyopathy) — an inherited condition where heart muscle, especially in the right ventricle, is gradually replaced by fatty and fibrous tissue, raising arrhythmia risk. See Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC).
  • Beta-Blocker — a medication that slows the heart rate and reduces the effect of stress hormones on the heart. See Medications 101.
  • Bradycardia — an abnormally slow heart rate, generally under 60 beats per minute; can be normal in athletes or a sign of a conduction problem depending on context.
  • BNP / NT-proBNP — a hormone released when the heart is under strain; measured by blood test to help diagnose and monitor heart failure. See Lab Tests & Diagnostics.
  • Cardiac Catheterization — a procedure using a thin tube threaded through a blood vessel to examine or treat the heart. See Procedures & Devices.
  • Cardiac MRI (CMR) — a detailed, non-invasive scan of the heart's structure and tissue characteristics. See Cardiac Testing & Imaging.
  • Cardiac Rehabilitation — a structured, supervised program of exercise and education after a cardiac event or procedure. See Cardiac Rehabilitation: Protocol, Succeeding & Life After.
  • Cardiogenic Shock — a life-threatening state where the heart can't pump enough blood to meet the body's needs.
  • CardioMEMS — a small implanted sensor that transmits daily pulmonary artery pressure readings from home. See Procedures & Devices.
  • Cardiomyopathy — a general term for disease of the heart muscle itself, of which there are several distinct types (dilated, hypertrophic, ischemic, amyloid).
  • Cardioversion — a procedure that delivers a controlled electrical shock (or medication) to reset an abnormal heart rhythm back to normal, commonly used for atrial fibrillation.
  • CABG (Coronary Artery Bypass Graft) — open-heart surgery that reroutes blood flow around blocked coronary arteries ("bypass surgery"). See Procedures & Devices.
  • Comorbidity — a separate medical condition existing alongside your primary diagnosis (for example, diabetes alongside heart failure) that can affect treatment decisions.
  • CPAP (Continuous Positive Airway Pressure) — a machine that delivers pressurized air to keep the airway open during sleep, the main treatment for obstructive sleep apnea.
  • CPET (Cardiopulmonary Exercise Test) — an advanced exercise test that measures oxygen use and breathing directly, often used in advanced heart failure and transplant evaluation.
  • CRT (Cardiac Resynchronization Therapy) — a specialized pacemaker that helps the heart's chambers beat in better sync. See Procedures & Devices.
  • Defibrillation — delivering an electrical shock to stop a dangerous, chaotic heart rhythm and allow the heart's normal rhythm to resume; the function an ICD performs automatically.
  • Denervated (Heart) — describes a transplanted heart's lack of the original direct nerve connections that were cut during surgery, which is why heart rate rises and falls more gradually with exertion than in a native heart. See Life After Transplant.
  • Diastole / Diastolic — the phase of the heartbeat when the heart's chambers relax and fill with blood; also the lower number in a blood pressure reading.
  • Diuretic — a "water pill" that helps the body eliminate excess fluid, commonly used in heart failure.
  • Driveline — the cable connecting an LVAD pump inside the body to its external controller and power source. See Driveline Care & Dressing Changes.
  • ECG / EKG (Electrocardiogram) — a quick recording of the heart's electrical activity using electrodes on the skin. See Cardiac Testing & Imaging.
  • Echocardiogram ("Echo") — an ultrasound of the heart that measures pumping function, valve health, and chamber size. See Cardiac Testing & Imaging.
  • Edema — medical term for swelling caused by fluid accumulation in tissue, commonly in the legs or abdomen with heart failure.
  • Ejection Fraction (EF) — the percentage of blood pumped out of the heart's main chamber with each heartbeat; a key measure of pumping strength.
  • Endocarditis — an infection of the heart's inner lining or valves, a serious condition requiring prompt treatment.
  • Endomyocardial Biopsy — a procedure that retrieves small tissue samples from inside the heart, often used to monitor for transplant rejection. See Procedures & Devices.
  • Etiology — the medical term for the cause or origin of a condition.
  • GLP-1 — a class of medications, originally for diabetes, now also used for weight management and shown to benefit certain heart conditions. See GLP-1 Medications: A Complete Guide.
  • Heart Failure — a condition where the heart doesn't pump or fill with blood as efficiently as the body needs; not the same as the heart "stopping." See Heart Failure.
  • HFpEF — heart failure with preserved ejection fraction, where the heart pumps normally but doesn't fill (relax) properly.
  • HFrEF — heart failure with reduced ejection fraction, where the heart's pumping strength itself is reduced.
  • Holter Monitor — a wearable device that continuously records heart rhythm, typically for 24–48 hours, to catch symptoms an office ECG might miss. See Cardiac Testing & Imaging.
  • Hibernating Myocardium — heart muscle that's alive but chronically under-supplied with blood and not contracting well, which can potentially recover function if blood flow is restored, unlike permanently scarred tissue. See Ischemic Cardiomyopathy.
  • Hypertrophy — thickening or enlargement of muscle tissue, in cardiology usually referring to thickened heart muscle walls.
  • ICD (Implantable Cardioverter-Defibrillator) — a device that monitors for dangerous fast heart rhythms and delivers a shock to correct them. See Procedures & Devices.
  • Immunosuppression — medications that reduce the immune system's activity to prevent organ rejection after transplant. See Medications 101.
  • Impella — a temporary mechanical pump inserted into the heart to support blood flow during cardiogenic shock or high-risk procedures. See Procedures & Devices.
  • Induction Therapy — a period of more intensive immunosuppression given around the time of transplant surgery to establish strong protection during the highest-risk early period, followed by a lower-intensity maintenance regimen. See Transplant Anti-Rejection Medications.
  • INR (International Normalized Ratio) — a blood test measuring how long blood takes to clot, used to monitor warfarin dosing. See Anticoagulants.
  • Intra-Aortic Balloon Pump (IABP) — a temporary support device that helps the heart pump and improves blood flow to the coronary arteries. See Procedures & Devices.
  • LDL / HDL — two types of cholesterol-carrying particles; LDL ("bad" cholesterol) contributes to artery plaque, while HDL ("good" cholesterol) helps remove it. See Hyperlipidemia.
  • LVAD (Left Ventricular Assist Device) — a mechanical pump that helps a weakened heart circulate blood, used as a bridge to transplant or as long-term therapy. See What Is an LVAD?.
  • Metabolic Syndrome — a cluster of risk factors (waist size, blood pressure, blood sugar, triglycerides, HDL) that together raise cardiovascular risk. See Metabolic Syndrome.
  • MRA (Mineralocorticoid Receptor Antagonist) — a medication class that's one of the "four pillars" of HFrEF treatment. See Medications 101.
  • Murmur — an extra heart sound caused by turbulent blood flow, which can be innocent or reflect underlying valve disease. See Cardiac Murmurs.
  • Myocardial Infarction (MI) — the medical term for a heart attack. See Heart Attack Recovery.
  • Myocarditis — inflammation of the heart muscle, often caused by a viral infection, which can temporarily or permanently weaken the heart.
  • Palpitations — an uncomfortable awareness of your own heartbeat, whether fast, irregular, or forceful — a symptom, not a diagnosis in itself. See Palpitations & Arrhythmias.
  • PACs / PVCs (Premature Atrial / Ventricular Contractions) — single extra or early heartbeats, usually harmless in an otherwise healthy heart. See Premature Atrial & Ventricular Contractions (PACs & PVCs).
  • PCI (Percutaneous Coronary Intervention) — a procedure using a balloon and usually a stent to open a blocked coronary artery. See Procedures & Devices.
  • Perfusion — the flow of blood through tissue, delivering oxygen and nutrients; "reduced perfusion" means an area isn't getting enough blood flow.
  • Pericardium — the thin sac surrounding the heart; can become inflamed (pericarditis) or fill with fluid (pericardial effusion).
  • Prognosis — the likely course and outcome of a medical condition, based on your specific situation rather than a single universal prediction.
  • Pulmonary Hypertension — high blood pressure specifically in the arteries between the heart and lungs. See Pulmonary Hypertension.
  • PYP Scan — a specialized nuclear scan used to help diagnose ATTR cardiac amyloidosis. See Cardiac Testing & Imaging.
  • Rejection (Transplant) — the immune system attacking a transplanted organ; monitored for with regular biopsies and managed with immunosuppression.
  • Resistant Hypertension — blood pressure that remains above target despite three or more medications from different classes at appropriate doses, which warrants a closer look for contributing causes. See Hypertension.
  • Right Heart Catheterization — a procedure that directly measures pressures inside the heart and lungs. See Procedures & Devices.
  • SGLT2 Inhibitor — a medication class originally for diabetes, now also a "pillar" of heart failure treatment. See Medications 101.
  • Sinus Rhythm — the heart's normal rhythm, originating from its natural pacemaker (the sinus node).
  • Statin — a cholesterol-lowering medication. See Medications 101.
  • Stent — a small mesh tube placed to hold open a blood vessel after a blockage is treated.
  • Stress Test — any of several tests (treadmill, pharmacologic, echo, or nuclear) that evaluate the heart's response to exertion. See Cardiac Testing & Imaging.
  • Swan-Ganz (Pulmonary Artery) Catheter — a catheter used to continuously monitor heart pressures, typically in an ICU setting. See Procedures & Devices.
  • Syncope — the medical term for fainting.
  • Systole / Systolic — the phase of the heartbeat when the heart's chambers contract and pump blood out; also the upper number in a blood pressure reading.
  • Tachycardia — an abnormally fast heart rate, generally over 100 beats per minute at rest.
  • Titration — the gradual, stepwise adjustment of a medication dose to find the right balance of benefit and tolerability.
  • Troponin — a protein released into the blood when heart muscle is damaged, measured to help diagnose a heart attack.
  • UNOS Status — the priority level assigned to a patient on the heart transplant waiting list, reflecting medical urgency. See Waiting for a Heart: Understanding UNOS Status.
  • Validated (Device) — a monitor whose accuracy has been formally tested against a clinical reference standard using a recognized protocol, not just factory-calibrated — the standard to look for in a home blood pressure monitor. See Taking Your Blood Pressure: Best Practices.
  • Vasodilator — a medication that relaxes and widens blood vessels, lowering blood pressure or reducing the heart's workload.
  • Ventricle — one of the heart's two main pumping chambers (left and right).