Cardiac Physiology: Clincal measurements and disease

Question 1

What blood markers are elevated in infarction?

Answer 1

Cardiac troponins T and I

Question 2

Which cardiac troponins are preferred markers for myocardial injury and why?

Answer 2

Cardiac troponins T and I; they have the highest sensitivities and specificities for the diagnosis of acute myocardial infarction

Question 3

Troponin is a contractile protein not normally found in serum. When are they released and can be detected?

Answer 3

Released only when myocardial necrosis occurs and can be detected in blood

Question 4

During infarction damaged cells lost the ability to repolarize. What is the mechanism of their injury?

Answer 4

Most damage occurs upon reperfusion and is associated with free radical damage; damaged area is in an abnormal state of depolarization

Question 5

What prolongs depolarization and therefore delays repolarization?

Answer 5

Ischemia

Question 6

Which arteries supply the myocardium?

Answer 6

Coronary arteries and their branches; cells near endocardium may be able to receive some O2 from chamber blood

Question 7

When does left coronary and right coronary flows peak?

Answer 7

Left: onset of diastole
Right: mid systole

Question 8

Which heart chamber is most limited by cardiac contraction

Answer 8

Left ventricle

Question 9

What causes systemic hypertension increasing workload on the left ventricle?

Answer 9

Systemic hypertension

Question 10

Anything that creates an abnormally high work load on a heart chamber can be contributed to?

Answer 10

Hypertrophy

Question 11

Axis

Answer 11

Average direction of ventricular depolarization

Question 12

What is the course of depolarization?

Answer 12

base to apex and from endocardium to epicardium (A.D.I.O.)

Question 13

Conduction block and hypertrophy that shifts axis

Answer 13

Axis deviation

Question 14

What is the normal axis range?

Answer 14

30-105 degrees

Question 15

First degree AV block

Answer 15

Depolarization wave from atria to ventricle is delayed excessively (PR interval > .2 s)

Question 16

Second degree AV block

Answer 16

Some depolarization waves pass, others blocked; dropped beat Pwave with NO associated QRS

Question 17

Third degree AV block

Answer 17

All depolarization waves from the atria to ventricles are blocked; No relationship between P waves and QRS complexes

Question 18

Measures potential difference across the surface of the myocardium with respect to time

Answer 18

EKG

Question 19

Line connecting leads in an EKG

Answer 19

Axis of lead

Question 20

Line perpendicular to axis of lead in EKG

Answer 20

Transition line

Question 21

Tachycardia is defined as?

Answer 21

Heart rate above 100 BPM

Question 22

Bradycardia is defined as?

Answer 22

Heart rate below 50 BPM

Question 23

EKG P wave

Answer 23

Atrial depolarization

Question 24

EKG QRS complex

Answer 24

Ventricular depolarization

Question 25

EKG T wave

Answer 25

Ventricular repolarization

Question 26

Time from SA node to entering the ventricle

Answer 26

PR interval; includes AV nodal delay

Question 27

What is a prolonged QT interval associated with?

Answer 27

Increased incidence of sudden cardiac death and high propensity to develop ventricular fibrillation

Question 28

What is associated with ventricular hypertrophy or conduction block in purkinje system?

Answer 28

Prolonged QRS complex