Cardiology Review

Middle of the thoracic cavity, attached to the thorax via great vessels

• Apex - Just above diaphragm left of midline
• Base - ~ 2nd rib

Endocardium - Inner most layer

Myocardium - Thick middle layer

Pericardium - protective sac surrounding the heart.

Visceral Pericardium(Epicardium) - Inner layer in contact with heart muscle. 

Parietal pericardium - Outer fibrous layer.

Myocardium

• Atria: receive blood from the body
• Ventricles: pump blood to lungs and body

• Tricuspid: between R atrium and R ventricle
• Mitral: between L atrium and L ventricle

• Pulmonary: from the R ventricle to the pulmonary artery
• Aortic: from the L ventricle to the Aorta

Superior/Inferior vena cava(deoxygenated blood) ---> R atrium ---> Tricuspid valve ---> R ventricle ---> Pulmonary Valve ---> Pulmonary artery ---> Lungs ---> Pulmonary Vein(oxygenated blood) ---> L atrium ---> Mitral Valve ---> L Ventricle ---> Aortic Valve ---> Aorta ---> Body

Coronary Arteries

Supply the left ventricle, interventricular septum, parts of the right ventricle and the hears conduction system. 

Anterior descending artery

Circumflex artery

Supplies portion of the right atrium/ventricle and part of the conduction system. 

• Posterior descending artery
• Marginal artery

CO= SV (stroke volume) x HR (heart rate)

• CO: amount of blood ejected (pumped) by the ventricles in 1 minute
• Normal adult CO= 5LPM

• Norepinephrine
• Increases HR and Cardiac contractile force

• Acetylcholine
• Slows both the HR and atrioventricular conduction.

Chronotropy - Refers to HR

Inotropy - Strength of cardiac muscular contraction. 

Dromotropy - The rate of nervous impulse conduction.

Alpha 1 - Located in the peripheral blood vessels. Responsible for vasoconstriction.

Beta 1 - Primarily in the heart. Increase HR and Contractility. 

Beta 2- Lungs and Peripheral blood vessels. Brochodilation and peripheral vasodilation.

Cells can respond to an electrical stimulus

Cells can propagate the electrical impulse from one cell to another

Ability to spontaneously initiate an electrical impulse

The ability to contract

• SA Node = 60-100 BPM
• AV Node = 40-60 BPM
• Purkinje system = 15-40 BPM

Potassium (K) - Influences repolorization. 

Sodium (Na) - Major role in depolarizing the myocardium

Calcium (Ca) - Takes part in myocardial depolarization and contraction

• Resting state with no electrical activity.  The inside of the cell is negative, outside is positive with uneven distribution of ions across the cell membrane.
• EKG Baseline

Inside of cell is positive, outside of cell is negative.

From the onset of QRS to approximately the peak of T wave.  Cells are depolarized and cannot be stimulated.

• "Vulnerable Period" because cells are repolarizing and can be stimulated (if stimulus is strong enough) thus possibly resulting in ventricular chaos.
• Downslope of T wave.

conduction disturbances, electrical effects of meds and electrolytes, and ischemic damage and injury.

• Toward positive electrode= upward
• Toward negative electrode= inverted (downward)

A straight line is recorded, called the "baseline" or "isoelectric" line

• Positive =  L leg electrode
• Negative = R arm electrode

RA (-) ----> LA (+)

RA (-) -----> LL (+)

LA (-) ----> LL (+)

Small square: 1mm x 1mm, 0.04 sec

Large square: 5mm x 5mm, 0.2 sec

atrial depolarization and spread of impulse across the L & R atria

End of P wave, beginning of QRS complex.  Usually represented by an isoelectric line

• From the beginning of the P wave to the beginning of QRS Complex.  Reflects the impulse travel time from the SA node through the AV node, Bundle of His, R & L bundles, and into the Purkinje fibers.
• Normal range= 0.12- 0.20

a negative deflection following the P wave. Always appears as a negative waveform.

First positive deflection following the P Wave or Q wave (if present).  Always appears as a positive waveform.

Negative waveform that follows the R wave.

R & S waves represent the depolarization of the L & R ventricles.

• Represents the depolarization of the ventricles and HR.
• Normal range= 0.04- 0.12

End of the S wave, beginning of the T wave

above or below by 1mm of the PR segment

• Depression: myocardial ischemia, digoxin, or low K
• Elevation: myocardial injury, infarction, or pericarditis, or cardiac tamponade.

3 I's of MI (ischemia, injury, infarction)

represents ventricular repolarization

• From beginning of Q to the end of the T wave. Represents total ventricular activity.
• Normal range= 0.33-0.42

SA ---> Internodal Pathways ---> AV Junction ---> AV Node ---> Bundle of His ---> L/R Bundle Branch --- (R Bundle) ---> apex of the R ventricle ---> Perkinje system --- (L Bundle) ---> Anterior/Posterior fascicles ---> Perkinje System