Cardiac Abnormalities

Question 1

Valvular abnormalities: Doesn’t open fully

Answer 1

called stenotic
Chamber upstream has to develop more pressure during systolic phase in order to achieve a given flow through valve
Increases “pressure” work (afterload) –> hypertrophy

Question 2

Valvular abnormalities: Doesn’t close completely

Answer 2

called insufficient

Regurgitant blood flow represents an additional volume that must be ejected in order to get sufficient forward flow.

Increases “volume” work (stroke volume)–> chamber dilation

Question 3

If capillary hydrostatic pressures are elevated, what will happen

Answer 3

tissue edema will occur, which will have consequences on function of upstream organs.

Question 4

Four common valve defects in left heart:

Answer 4

Aortic Stenosis
Mitral Stenosis
Aortic Insufficiency (Regurgitation)
Mitral Insufficiency

Similar stenotic and regurgitant abnormalities can occur in the right ventricular valves with similar consequences on function.

Question 5

Aortic Stenosis

Answer 5

Aortic valve doesn’t open fully-Increased resistance to flow

Question 6

Mitral valve stenosis

Answer 6

Mitral valve doesn’t open fully
Increased resistance to flow
Characteristic Signs:
Pressure difference of more than a few mmHg across the mitral valve during diastole
Elevated left atrial pressure
Turbulent flow of blood leads to diastolic murmur
May induce hypertrophy of left atrial muscle
Primary physiological consequence: high left atrial and pulmonary capillary pressures

Question 7

Aortic Insufficiency

Answer 7

Leaflets of aortic valve do not seal
Blood regurgitates back into LV during diastole
Characteristic Signs:
Aortic pressure falls faster/farther than normal during diastole
Low diastolic pressure
Large pulse pressure
Ventricular EDV and EDP are higher than normal because extra blood reenters the chamber
Turbulent flow of blood reentering LV causes diastolic murmur
Primary physiological consequence: reduced ejection fraction, increased volume workload
Often aortic valve is BOTH stenotic and insufficient… in this case both systolic and diastolic murmurs will be heard

Question 8

Mitral Regurgitation

Answer 8

Leaflets of mitral valve do not seal
Blood regurgitates back into left atrium during systole
Characteristic Signs:
Left atrial pressure is abnormally high
Left ventricular EDV and EDP increase
Systolic murmur
Primary physiological consequence: ejection fraction from left ventricle compromised, increased volume workload on LV
May lead to pulmonary effects with shortness of breath
Prolapse is the most common form –> valve leaflets evert into left atrium during systole

Question 9

Supraventricular Abnormalities Originate

Answer 9

in atria or AV node

Question 10

Paroxysmal supraventricular tachycardia (PSVT)

Answer 10

A rapid, usually regular rhythm, originating from above the ventricles. PSVT begins and ends suddenly.
Low blood pressure and dizziness common

Question 11

Sinus Node Dysfunction

Answer 11

A slow heart rhythm due to an abnormal SA (sinus) node.

Example: Sinus Arrest with pause for 3+ seconds with no SA node activity

Question 12

Heart block

Answer 12

Heart block
A delay or complete block of the electrical impulse as it travels from the sinus node to the ventricles. The level of the block or delay may occur in the AV node or HIS-Purkinje system. The heart may beat irregularly.
Often the heart rate is slower too.

Question 13

First Degree Block:

Answer 13

unusually slow conduction
Abnormally long PR interval (>0.2 sec)
ECG otherwise normal

Question 14

Second Degree Block:

Answer 14

some, but not all, atrial impulses transmit through AV node due to slower than normal conduction
Some, but not all P waves accompanied by QRS & T wave

Question 15

Third Degree Block:

Answer 15

no impulses are transmitted through AV node, pacemaker defaults to His (usually, not always), atrial and ventricular rates independent
P waves and QRS are totally dissociated in ECG
P waves are equally spaced, QRS are equally spaced
Ventricular rate likely slower than normal because of alternate pacemaker –> often slow enough to impair cardiac output

Question 16

Premature atrial contractions (PACs)

Answer 16

Supraventricular Arrhythmia

Early extra beats that originate in the atria

Question 17

Accessory pathway tachycardias

Answer 17

A rapid heart rhythm due to an extra abnormal pathway or connection between the atria and the ventricles. The impulses travel through the extra pathways (short cuts) as well as the normal AV-HIS Purkinje system. This allows the impulses to travel around the heart very quickly, causing the heart to beat unusually fast.

Question 18

AV nodal reentrant tachycardia (AVNRT)

Answer 18

A rapid heart rate due to more than one pathway through the AV node.
Atrial tachycardia
Atrial fibrillation
Atrial flutter

Question 19

Atrial tachycardia

Answer 19

A rapid heart rate originating in the atria.

Question 20

Atrial fibrillation

Answer 20

A very common irregular heart rhythm. Many impulses begin and spread through the atria, competing for a chance to travel through the AV node. The resulting rhythm is disorganized, rapid, and irregular. Because the impulses are traveling through the atria in a disorderly fashion, it results in loss of coordinated atrial contraction.
Depolarization / Repolarization happening randomly throughout atria
No P waves appear in ECG
May be rapid, irregular, small wave apparent throughout diastole
Ventricular rate irregular

Question 21

Atrial flutter

Answer 21

An atrial arrhythmia caused by one or more rapid circuits in the atrium. Atrial flutter is usually more organized and regular than atrial fibrillation.

Question 22

Bundle Branch Block

Answer 22

Also called Hemiblocks

Occur in either of the branches of the Purkinje system of the intraventricular septum:
Often due to myocardial infarction
Widening of QRS (>0.12 sec) because Ventricular depolarization less synchronous in half the heart
Split of the R-wave

usually inconsequential

Question 23

Premature ventricular contractions (PVCs)

Answer 23

PVCs are early extra beats beginning in the ventricles.
PVCs are common.
Mostly cause no symptoms and require no treatment.
can be related to stress, too much caffeine or nicotine, or exercise.
sometimes can be caused by heart disease or electrolyte imbalance.
Large amplitude, long duration QRS deflections on ECG
Shapes are variable –> depend on ectopic site of origin and depolarization pathway involved

Question 24

Ventricular tachycardia (V-tach)

Answer 24

A rapid rhythm originating from the lower chambers of the heart.
rapid rate prevents the heart from filling adequately with blood, and less blood is able to pump through the body.
This can be a more serious arrhythmia, especially in people with heart disease, and may be associated with more symptoms.
Often precedes Ventricular Fibrillation

Question 25

Long QT Syndrome

Answer 25

Delayed ventricular myocyte repolarization
QT interval is prolonged if > ~450ms
Long QT is defined as greater than 50% cycle duration
When QT is longer than normal, it increases the risk for torsade de pointes, a life-threatening form of ventricular tachycardia.

Question 26

torsades de pointes

Answer 26

differs from normal v-tac in that QRS complexes cyclically vary in amplitude around the baseline and can deteriorate rapidly to v-fib

Question 27

Ventricular fibrillation

Answer 27

An erratic, disorganized firing of impulses from the ventricles. The ventricles quiver and are unable to contract or pump blood to the body. This is a medical emergency that must be treated with cardiopulmonary resuscitation (CPR) and defibrillation as soon as possible.