Glossary of Terms
| Ablation | Procedure to destroy tissue that is abnormal or malfunctioning. In cardiac procedures it is often a catheter procedure, using heat, cold or electrical energy. Common to atrial fibrillation treatment. |
| Afterload | The resistance in the systemic circulation the ventricle must overcome to eject blood (systole). It is dependent on blood volume, blood viscosity and blood pressure. A stiff aortic valve can also be a source of resistance. |
| Agonist | A substance or drug chemical that binds to a receptor and results in a biological response. Agonists can cause a full response or a partial response (called sympathomimetic) |
| Anastomosis | A surgical connection between two structures, such as blood vessels. In open heart surgery these are manual stitched connections by the surgeon to reroute blood flow. |
| Aneurism | an abnormal bulge or ballooning in the wall of a blood vessel. An aneurysm can burst. This is called a rupture. A ruptured aneurysm causes bleeding inside the body and often leads to death. |
| Angina | A symptom related to heart disease. Characterized by pain in the chest, jaw, shoulder or back. The pain is a result of a lack of oxygen delivered to the heart. It can be transient from a mismatch in oxygen demand and supply to the heart or occur during a myocardial infarction. |
| Angioplasty or PCI | Percutaneous Coronary Intervention. A procedure where a catheter equipped with a balloon is sent upstream on the arterial side (femoral or radial) to an occluded area in a coronary artery. The balloon is inflated, and the area is widened. |
| Antagonist | A substance or drug chemical that binds to a receptor and blocks its activation, preventing a biological response. |
| Atelectasis | The collapse or incomplete expansion of the lungs. This is a common occurrence for open heart surgery patients who were on a heart-lung bypass machine. Their lungs had collapsed and have yet to fully recover. Clinicians often have patients cough or “huff” to help create back pressure to help inflate the lungs. Exercise is also used. |
| Atherosclerosis | A chronic, inflammatory disease characterized by a buildup of cholesterol-laden plaque on the interior of the arteries, ultimately reducing blood flow to vital organs. |
| Arrhythmia | An abnormality of the heart in rhythm or rate. Synonymous with dysrhythmia |
| Automaticity | The intrinsic ability of a cell (such as a cardiac cell) to generate electrical impulses and contract rhythmically without external stimulation. Different cells of the heart have different firing rates, with the SA node having the fastest. |
| a-VO2 Difference | The difference in oxygen content between the arterial side and the venous side. It is representative of the oxygen extracted by the tissue. Influenced by blood flow to a tissue bed, density of capillaries and the size and number of mitochondria. |
| Biphasic | Biphasic used as a term in electrocardiography refers to a cardiac wave that has 2 phases. Often one phase is a positive deflection, and another is a negative deflection. Sometimes the term “equiphasic” is also used. |
| Bioavailability | The proportion or percentage of a drug or substance that becomes available to exert its effect after administration. Factors affecting bioavailability include the route of administration, absorption, distribution, and metabolism. |
| Cannula | A thin tube that is inserted into the body to administer fluids or redirect fluids, such as is the case with a heart lung bypass machine. |
| Cardiac Output (Q) | Cardiac output is the volume of blood ejected by the heart each minute. It is calculated as Stroke Volume x Heart rate. |
| Cardioplegia | A technique of administration of a solution containing potassium, magnesium, and calcium to stop the heart by eliminating voltage gradients across cell membranes. This is used during open heart surgery so that the surgeon can operate on a still heart. |
| Cardioversion | A timed defibrillation procedure where the depolarization shock is synchronized with the ventricular systole to prevent inducing dangerous arrhythmias. It is used in cases of atrial fibrillation, flutter and SVT. Chemical cardioversion is also possible with medications such as flecainide, amiodarone or propafenone. |
| Catheter
Chronotropy |
A thin, flexible tube used in medical procedures to gain access to the body to introduce or remove fluids. Catheters can also move within the blood vessels and carry equipment used in cardiac procedures, such as angioplasty and ablation. Urinary catheters drain urine from the bladder when individuals are not able to move or urinate on their own.
Refers to the influence of factors that affect the heart rate (HR), specifically the rate at which the heart beats. It encompasses mechanisms that can either increase (positive chronotropy) or decrease (negative chronotropy) heart rate. |
| CK-MB | Creatine Kinase-Myocardial Band is an enzyme within heart tissue. During a myocardial infarction, damaged cardiac tissue releases CK-MB into the blood, where it can be measured as evidence of an acute myocardial infarction. It is used as a blood marker of MI. |
| Claudication
Cold spot |
Pain or cramping in the legs during physical activity. The pain usually resolves with rest. Most often this pain is due to peripheral artery disease and is caused by local ischemia and the accumulation of lactic acid.
An area on a cardiac imaging test, such as a Thallium scan, that lacks color, indicating a lack of blood flow to an area of the myocardium. If the cold spot is seen on both the resting image and stress image this indicates necrotic (dead) tissue. if the spot is only seen on the stress image, it is indicative of ischemia and is reversible. |
| Contraindication | A specific condition, disease or other measure that makes a particular treatment or activity potentially harmful, and therefore should not be done. Driving under the influence of alcohol is contraindicated because vision and reaction time is impaired, making driving very dangerous. |
| Coronary Steal | A condition related to disease or atherosclerotic coronary arteries. Diseased arteries do not dilate during exercise or other vasodilation stimuli. However healthy arteries do dilate, and redirect blood flow away from the diseased arteries, resulting in reduced blood flow to through the diseased arteries, causing ischemia. |
| Defibrillation | A medical treatment for life threatening arrhythmias, such as ventricular fibrillation, where cardiac cells randomly fire, resulting in no coordinated ventricular contraction. Defibrillation sends an electric shock through the heart, depolarizing all cells at once, with the hope that the SA node resumes its role as the normal pacemaker. Defibrillation can be done externally to the chest, and internal defibrillators can be implanted as part of a pacemaker. |
| Diaphoresis | Excessive sweating, beyond what is a normal response to the environment. Non exercise reasons for diaphoresis may be anxiety, stress, adverse reaction to medication, myocardial infarction, and fever. |
| Diastole | The relaxation phase of the heart where there is no ventricular contraction. The pressure within the arterial system during the diastolic phase is known as Diastolic Pressure. |
| Diuresis | The increased production of urine by the kidneys leading to increased urine output. Diuresis may be in response to increased blood pressure hormonal regulation to balance electrolytes or some medications such as diuretics. |
| Dropped Beat | Refers to a missing QRS complex following an atrial beat. For example, in conduction defects such as a second-degree AV block the are some P waves present that do not have a subsequent QRS, due to the AV block. This missing QRS is a dropped beat. |
| Dyspnea | Difficulty breathing characterized by breathlessness and a feeling of not being able to get enough air in the lungs to relieve the distress. Causes can include COPD, anxiety, deconditioning, and edema caused by heart failure. |
| Dysrhythmia | An abnormality of the heart in rhythm or rate. Synonymous with arrhythmia |
| Ectopic-Ectopy | The occurrence of premature beats, such as PVCs PAC and PJCs |
| Edema | An abnormal accumulation of fluid in the interstitial spaces. The accumulation can occur in the leg (peripheral edema) lungs (pulmonary edema) and the arms and abdomen(ascites) |
| Ejection Fraction (EF) | The percentage of blood ejected from the left ventricle relative to the end diastolic volume. It is a key measure of heart contraction strength. EF= (stroke volume/ EDV) x 100 |
| End-diastolic Volume | The volume in the ventricle at the end of diastole. It is influenced by venous return, preload and heart rate. At high heart rates, EDV is reduced due to shorter filling times. This is especially important in cases of accelerated heart rhythms such as SVT and ventricular tachycardia. |
| End-systolic Volume | The volume in the ventricle at the end of systole. It is influenced by both preload and afterload as well as the strength of heart contraction. |
| Endocardium | The innermost lining of cardiac tissue in the heart |
| Hemodynamic | The study of the pressure and flow of the blood in the body. |
| Hypokalemia | A reduction in blood potassium. This can occur due to excessive potassium intake, diuretic use, vomiting and diarrhea, excessive seating or kidney disorders. |
| Hypokinesis | A reduction in normal movement or contraction. In cardiac muscle this is reduce contractile action of the cardiac chambers, due to ischemia or necrotic (dead) tissue) |
| Hyponatremia | A condition of low blood levels of sodium. This can occur due to dehydration, excessive water intake and medication use (thiazide diuretics) |
| Hypercalcemia | A condition of elevated levels of blood calcium. This may occur due to hyperparathyroidism, high calcium intakes, and diuretic use |
| Hyperglycemia | High levels of blood glucose. Hyperglycemia during a fasted measurement is seen in diabetic patients and represents either a failure to produce insulin (type I) or an impairment in the insulin- insulin receptor binding (type II). Some symptoms of hyperglycemia include increased thirst, frequent urinations, fatigue, dry mouth, and headaches. |
| Idiopathic | A disease or condition that arises spontaneously and from an unknown cause. This often makes treatment difficult since the cause of the condition is unknown. |
| Indication
Inotropy |
A sign or circumstance that suggests a course of action should be taken. Term used in drug referencing to identify a particular use of a medication. For example, a beta blocker is indicated for the treatment of hypertension and angina.
Inotropy refers to the contractile strength or force of cardiac muscle cells, particularly in relation to the heart’s function. |
| Intercostal | Between the ribs in the chest wall. Placement of ECG electrodes that use boney landmarks also use intercostal spaces as locations for electrode placement. For example, V4 is placed at the midclavicular line and 5th intercostal space. |
| Ischemia | Inadequate blood (and therefore oxygen) supply to a tissue. A narrowed or blocked coronary artery results in reduced blood flow to an area of the heart, resulting in reduced oxygen availability. |
| Isoelectric line | The baseline or zero line on the electrocardiogram where there is no electrical activity present. This is the line between the end of the T wave and the beginning of the P wave, and the PR segment. Measures of ECG wave magnitude is made from the isoelectric line (i.e. voltage, ST segment depression) |
| Mean Arterial Pressure (MAP) | A value that represents the average pressure in the arteries during a single cardiac cycle. It is calculated as: Diastolic pressure + 1/3 pulse pressure. A blood pressure of 120/80 is a MAP of 93. Below 60-70mmHg MAP cerebral perfusion may be inadequate and the patient may lose consciousness. |
| MET | Metabolic Equivalent. A term used to describe metabolism and oxygen consumption by a huma. I MET equals 3.5 ml/kg/min of oxygen use. The cost of activities can be quantified by how many METs is required to perform the activity or exercise intensity. |
| Morphology | In electrocardiography, morphology refers to the shape or structure of an electrical wave. Certain cardiac abnormalities or conditions are identified by the shape of the ECG wave. An example is the “swooped” ST segment in patients taking digitalis. |
| Multifocal | Many locations. In ECG terms, this refers to premature beats that come from more than one location. For example, if two PVCs occur but they look different, then they came from different locations, and we refer to them as multifocal PVCs. |
| Muscle Pump | Contraction of muscle, primarily in the legs, that squeezes veins, causing increased venous return. This is especially important post exercise to prevent sudden drops in blood pressure due to venous blood pooling. |
| Myocardium | The middle and thickest layer (between endocardium and epicardium) of the heart muscle. |
| Myocardial Infarction | Often called a “heart attack” is when a coronary artery is blocked and blood flow to a portion of the heart is stopped, leading to cell death. |
| Necrosis | Referring to cell death. Necrotic tissue is dead tissue, as happens with a myocardial infarction. |
| Occlusion | Refers to the complete blockage of a blood vessel or other tubular structure. Sometimes coronary artery degree of blockage is referred to as a percent occlusion. Sometimes used synonymously with the term “Stenosis.” |
| Orthostatic Hypotension | A sudden drop in blood pressure when someone moves from supine or seated to standing. This is often accompanied by symptoms of dizziness, pallor complexion and possibly fainting. |
| Pallor | Abnormal whitening or pale complexion or tissue bed. It can be a symptom of reduced blood flow to an area. |
| PCI or angioplasty- | Percutaneous Coronary Intervention. A procedure where a catheter equipped with a balloon is sent upstream on the arterial side (femoral or radial) to an occluded area in a coronary artery. The balloon is inflated, and the area is widened. |
| Perfusion | The process of delivering blood, oxygen and nutrients to tissue and organs. In heart disease, arteries that are partially occluded can result in decrease perfusion to tissue. |
| Preload | The stretch or filling of the heart chambers during the diastolic phase. This represents a load that must then be ejected during systole. Venous return influences preload, and in cases of heart failure, extra fluid retained can cause a heavy preload that overstretched the ventricle, causing added work for the heart, and reducing its ability to contract. |
| Prolapse | Refers to the abnormal displacement of a tissue or organ from its usual position. For example, mitral valve prolapse is when the valve leaflets bulge backwards into the atrial, causing regurgitation of blood into the atrial during ventricular systole. |
| Pulse Pressure | The pressure difference between the systolic pressure and diastolic. For example, with a blood pressure of 120/80 the pulse pressure is (120-80) 40 mmHg. High pulse pressures can be indicative of stiff blood vessels. |
| Rate Pressure Product | An index of myocardial oxygen use (“work of the heart”). RPP is calculated as heart rate x systolic blood pressure. |
| Re-entrant Circuit | A lesion of pathway of slow conducting, short refractory tissue that can be activated by a premature beat, causing a fast-contracting circuit leading toa high speed pacing of the heart (examples, atrial flutter, ventricular tachycardia, SVT) |
| Respiratory Pump | A pump mechanism that helps pull blood back to the heart (venous return) during the low-pressure inspiration by reducing intrathoracic pressure. |
| Regurgitation | The abnormal backflow of fluid. With respect to a heart valve, blood typically flows in one direction through an open valve and then when the valve closes, flow cannot go back. However impaired valves can create openings allowing for blood to flow backwards. Mitral valve prolapse is a condition where regurgitation occurs. |
| Retrograde | In the opposite direction. In ECG terms, premature beats occurring in the AV node are sometimes conducted in opposing directions. One signal travels the normal direction and down into the ventricle, but another signal moves in the opposite (retrograde) direction into the atrial, causing an inverted P wave. |
| Secondary Prevention | Measures to reduce the risk of additional heart disease complications in patients with latent disease. These measures can include cardiac rehab, nutrition counseling, stress management, medications, and smoking cessation. |
| Sign | These represent things that can be measured or identified on the body, such as blood pressure, body temperature, and oxygen saturation. |
| Stenosis | The abnormal narrowing of a tubular structure, such as a coronary artery. Sometimes used synonymously with the term” Occlusion.” |
| Stent | A small, metal mesh-like tube that is placed in the coronary artery to keep a blood vessel open after a PCI or angioplasty procedure. Typically, it is put in place following balloon angioplasty has widened a narrowed area in the artery. |
| Sternotomy | A surgical procedure involving the cutting of the sternum lengthwise to gain access to the heart and surrounding tissue. |
| Strain Pattern | A pattern seen on the ECG, particularly the QRS and T wave complex. Typically, it is a combination of ST segment depression and T wave inversion. Left ventricular strain patterns are often seen in left ventricular hypertrophy, left bundle branch block and cardiomyopathy. |
| Stroke Volume | The volume of blood ejected from the left ventricle with each contraction. |
| Subendocardium | The innermost layer of tissue, lining the inner chambers of the heart muscle. It also contains the Purkinje fibers and conducts electrical signals to the myocardium. During ischemia, this tissue is often the first to experience a reduction in blood and oxygen. |
| Sublingual | Under the tongue. Some medications that bypass the GI and are absorbed directly into the blood are given sublingually (i.e nitroglycerine) |
| Sulci | This refers to grooves or furrows. These are found on the surface of the heart and are where the coronary arteries sit. Sulci are compressed during ventricular systole but relaxed during diastole. This is how the ventricle can get its own coronary blood supply during the diastolic phase. |
| Supine | Relaxed position where the patient lies flat on their back, arms at their side. |
| Symptom | Symptoms may be reported by the patient (“my chest hurts”) or you might notice the symptoms displayed by observing them (patient began to walk with an uneven gait, with the left side losing control). |
| Systole | The contractile phase of the cardiac cycle. The pressure generated during this phase is the systolic blood pressure. |
| Systemic Circulation | Movement of blood from the heart, through arteries, arterioles, and capillaries, delivering nutrients to the cells. It is also deoxygenated blood in the venules, veins, and blood circulating back to the right atrium. |
| Thrombus | A blood clot that forms in a blood vessel or in the heart. |
| Thrombolytic | Refers to something that breaks down blood clots. |
| TIMI | Thrombolysis in myocardial Infarction. A grading system of flow, where 0= no flow and 3 = normal flow |
| Transdermal | “Across the skin”. Refers to chemicals such as drugs that can be delivered to the system and bypassing digestion. For example, nitroglycerin can be delivered directly to the blood via a transdermal nitro patch. |
| Transducer | A device that converts electrical energy into some other form of energy. For example, in echocardiography the transducer converts electrical energy into sound waves, which can be used to visualize the heart or other internal structures. |
| Transmural | “Across the wall”. In the myocardial muscle this means across the entire width of the myocardial wall |
| Troponin I | Contractile protein. “I” form located in the heart. When it is found in the blood it is a marker for an acute myocardial infarction |
| Unifocal | Meaning “one focus” or one location. Used in terms of premature beat locations. If two PVCs look the same, they are unifocal. |
| Valsalva | Exhaling against a closed resistance. This can be as simple as breath holding, or with much more force, like during a heavy lift. For heart patients this can be dangerous, as it also causes substantial increases in blood pressure. |
| Venous Capacitance | The ability of the veins to expand and contract and serve as a reservoir of blood and help maintain venous pressure and cardiac output. |
| Venous Return | Refers to the blood returning to the heart (right atrium) from the venous circulation. Venous return can be influenced by posture, the skeletal muscle pump, and the respiratory pump. |
