Cardiovascular System and 12-Lead EKG Review

Vocabulary flashcards generated from lecture notes covering cardiovascular pathophysiology, cardiac conduction, and 12-lead EKG procedures.

Layers of blood vessels

The three structural layers composing blood vessel walls: tunica intima (innermost layer), tunica media (middle muscular layer), and tunica adventitia/externa (outer protective layer).

Difference between arteries and veins

Arteries carry blood away from the heart under high pressure and have thicker, more elastic walls; veins carry blood toward the heart under lower pressure, have thinner walls, and contain valves to prevent backflow.

Angina

Chest pain or discomfort caused by reduced blood flow and oxygen supply to the heart muscle (myocardium).

Ischemia

An inadequate blood supply to a local area of tissue or organ, causing a shortage of oxygen and nutrients.

Right sided heart failure

Inability of the right ventricle to pump blood efficiently to the lungs, leading to systemic venous congestion, peripheral edema, and ascites.

Left sided heart failure

Inability of the left ventricle to pump blood efficiently to the rest of the body, causing blood to back up into the lungs and leading to pulmonary edema.

Ascites

An abnormal accumulation of fluid within the peritoneal cavity, commonly seen in right-sided heart failure.

Peripheral edema

Swelling in the tissues of the lower extremities (legs, ankles, feet) due to fluid accumulation, often associated with right-sided heart failure.

Pulmonary edema

Fluid accumulation in the lungs and alveoli, commonly caused by left-sided heart failure.

Valve insufficiency and regurgitation

A condition where a heart valve fails to close completely, allowing blood to leak backward (regurgitate) into the preceding cardiac chamber.

Purpose of the heart valves

To ensure unidirectional (one-way) blood flow through the heart and prevent the backward flow (regurgitation) of blood.

Occlude

To block, obstruct, or close off a blood vessel or duct.

DVT

Deep Vein Thrombosis; the formation of a blood clot (thrombus) within a deep vein, most commonly in the legs.

Embolus vs. Thrombus

A thrombus is a stationary blood clot attached to the wall of a blood vessel; an embolus is a detached, traveling mass (clot, air, fat) carried through the bloodstream.

Echocardiogram vs. echocardiograph

An echocardiogram is the visual record or graphic output produced by ultrasound of the heart; an echocardiograph is the machine or instrument used to perform the test.

Repolarization (of cardiac cells)

The recovery phase of cardiac muscle cells during which the electrical potential across the cell membrane returns to its resting negative state.

Depolarization (of cardiac cells)

The electrical activation phase of cardiac cells in which membrane potential shifts toward positive, triggering cardiac contraction.

Electrodes used for a 12-lead EKG

10 physical electrodes placed on the body (4 limb electrodes and 6 chest electrodes) to record 12 electrical leads.

Einthoven's triangle

An imaginary equilateral triangle formed around the heart by the three limb electrode positions (right arm, left arm, left leg) used to measure bipolar leads I, II, and III.

Wilson's Central Terminal

A central electrical point created by connecting the three limb electrodes through equal resistance, serving as a zero-reference point for unipolar leads.

Bipolar leads

Leads I, II, and III (limb leads), which measure electrical potential difference between two specific limb electrodes.

Unipolar leads

Leads avF, avL, avF, V1-V6, which measure electrical potential in one direction relative to a zero reference.

Limb leads

Electrodes placed on the limbs using four specific color-coded wires: white, green, red, and black.

Precordial leads

The six chest leads designated as V1, V2, V3, V4, V5, and V6.

Grounding lead in an EKG

The right leg (RL) lead electrode, which acts as an electrical ground reference and does not produce a visual trace view of the heart.

Nuclear stress test

A diagnostic cardiac test using a small amount of radioactive tracer injected into the bloodstream along with imaging to evaluate blood flow through the heart muscle during stress and rest.

Target heart rate for an EKG stress test

The calculated minimum heart rate (typically 85% of maximum predicted heart rate, computed as $220 - \text{age}$) that a patient must reach during testing.

EKG machine standardization frequency

The regular schedule or routine check performed prior to and after each patient recording or test run to ensure accurate voltage and timing measurement.

Proper standardization of an EKG machine (speed and voltage)

Standard paper speed is $25\text{ mm/s}$ and standard voltage gain is $10\text{ mm/mV}$ ($1\text{ mV} = 10\text{ mm}$ high calibration box).