Cardiology Review: The Heart and Conduction System

The heart is a muscular pump with four chambers that circulate blood through the body.

Heart valves control the direction of blood flow through the heart.

The heart muscle. Its powerful contractions pump blood.

A specialized network of fibers that create and conduct electrical impulses for heart contraction.

The sinoatrial node; the heart's natural pacemaker, initiating electrical impulses.

The atrioventricular node; a relay point in the heart's electrical system.

Blood vessels that supply the heart muscle with oxygen.

A condition where the heart isn't effectively pumping blood, causing fluid buildup.

A disease where blood flow to the heart muscle is reduced due to narrowed coronary arteries.

Hardening and stiffening of artery walls, common with age.

Fatty deposits (plaques) buildup inside arteries, narrowing them.

Chest pain due to insufficient blood flow to the heart muscle.

A heart attack; a serious event where part of the heart muscle dies due to lack of blood.

Nitroglycerin opens blood vessels, reducing workload on the heart and easing chest pain by vasodilation, primarily targeting venous circulation.

Nitroglycerin transforms into nitric oxide (NO), a potent vasodilator, widening blood vessels ultimately decreasing oxygen demands and blood pressure, reducing workload of the heart to lower pain.

Preventing angina by reducing the frequency of painful episodes

Used to relieve the sharp pain of an angina attack.

Place the medication under the tongue, let it dissolve to allow rapid absorption into bloodstream.

Headache, flushing, and dizziness due to vasodilation.

A maximum of three doses within a timeframe to address an acute angina attack. After three doses if pain persists, seek immediate help.

Nitroglycerin comes in many forms: Sublingual tablets and spray for acute attacks, Ointment and oral/topical patches for prevention. IV form exists for emergencies

Calcium channel blockers that are potent vasodilators.

Calcium channel blockers with stronger negative inotropic effects (affecting heart muscle contraction).

Chest pain caused by reduced blood flow to the heart.

Arrhythmias starting in the atria or AV node (top of heart).

Arrhythmias originating below the AV node (bottom of heart).

Rapid heart rate (over 100 bpm).

Slow heart rate (below 60 bpm).

Abnormal areas in the heart that generate irregular heartbeats.

Antiarrhythmic drugs that block sodium channels, affecting heart excitation and conduction.

Drugs that inhibit calcium entry into heart and vascular cells, reducing heart work and blood vessel tone.

Typical symptoms include tiredness, shortness of breath, rapid heartbeat, and swelling (edema).

Often involves vasodilators and beta-blockers to lower peripheral resistance and blood pressure, improving heart function.

A specific class 2 antiarrhythmic drug available as tablets.

Class 4 antiarrhythmics, commonly used to treat supraventricular tachycardias, also effective against hypertension & angina. Supplied as tablets/capsules and intravenous injection.

Diuretics help eliminate excess sodium and water from the body through urination. This reduces blood volume, swelling (edema), and the workload of the heart.

Digoxin is used as a third-line treatment option for heart problems when other therapies like diuretics and vasodilators haven't been successful. It's also used when the heart muscle itself is weak and can't pump effectively.

Cardiac glycosides are a group of drugs derived from plants like Digitalis purpurea and Digitalis lanata. They are often used to treat heart failure and some types of irregular heartbeat.

Cardiac glycosides increase the strength of heart contractions in heart failure without increasing oxygen consumption by the heart. This results in stronger, faster contractions, allowing the heart to pump more blood with each beat.

Digoxin is available as a pill (oral) or as an injection (intravenous). It can be given in a rapid dose initially (digitalization) to quickly reach effective levels in the body. Then a smaller, daily dose is used to maintain those levels.

A narrow therapeutic index means that the difference between a safe and effective dose and a toxic dose is very small. This means careful monitoring is crucial to avoid harmful side effects.

Adverse effects of cardiac glycosides are usually caused by overdose and can include nausea, vomiting, headache, vision problems, and skin rashes. More serious effects like irregular heartbeat, extra heartbeats, fast heart rhythms, and even heart arrest can occur. These effects can be treated by stopping the drug, replacing potassium levels, and using anti-arrhythmic medications.

Cardiac glycosides are highly sensitive to changes in electrolytes like potassium, calcium, and sodium. Low potassium levels increase the risk of toxicity, while high potassium levels reduce their effectiveness. High calcium levels enhance the action of cardiac glycosides.

A period of time each day where a patient on maintenance nitrate therapy should avoid taking nitrates to prevent tolerance development.

Beta blockers block beta receptors in the heart, reducing heart rate and force of contraction, leading to lower oxygen demand and workload.

A beta blocker that affects multiple areas of the body, including the heart, lungs, blood vessels, and kidneys.

A beta blocker that primarily targets the heart, minimizing effects on other organs.

Nitrate medications used to treat angina, with dinitrate for acute attacks and mononitrate for long-term maintenance.

Isosorbide nitrates act like nitroglycerin, by dilating blood vessels to reduce heart workload and oxygen demand, easing chest pain.