Cardio 4

Question 1

Describe the ECG.

Answer 1

Determination of:
-HR
-heart rhythm
-wave form morphology (amplitude & duration)

Question 2

Describe the P wave.

Answer 2

-1st ECG deflection
-depol of atria
-discharge of SA node = prior to P wave
>no deflection for SA node discharge = small # of cells
no deflection for atrial repol

Question 3

Describe left atrial enlargement.

Answer 3

LA & ventricular enlargement
-wide QRS complex
-wide & notched P wave

Question 4

Describe sick sinus syndrome.

Answer 4

absence of P wave
1. Junctional beat
-no SA node
-no P wave
-other conduction cells (AV node)
2. Sinus arrest
3. Ventricular escape beat
-cells in ventricle sends AP
-bottom to top
-inverted

Question 5

Describe the P-R segment.

Answer 5

-P wave followed by return to baseline
-end of P & beginning of Q
-AV node conduction
>flat line bc cells are too small to generate sufficient voltage

Question 6

Describe the P-R interval.

Answer 6

-represents time it takes for the electrical impulse to conduct from the SA node through the atria & AV node & bundle of HIS
-start of P wave to first deflection of QRS
-sympathetic stimulation decreases PR interval
>increases conduction velocity
-parasympathic stimulation increases PR intervals
>decreases conduction velocity

Question 7

Describe the QRS complex.

Answer 7

-impulse activates the HIS-purkinje system & ventricular muscle
-3 waves = ventricular depol
-total duration of QRS complex is similar to P wave
>faster conduction velocity
-each wave = specific place of ventricle being depol

Question 8

Describe the Q-T interval.

Answer 8

-reflects approx. duration of ventricular systole & ventricular refractory period
-beginning of Q wave to end of T wave

Question 9

Describe the S-T segment.

Answer 9

-plateau of ventricular AP
-ending of depol & beginning of repol
-isoelectric = all ventricular muscle is depol

Question 10

Describe the T wave.

Answer 10

-ventricular repol
-longer duration than QRS bc repol doesn’t occur as synchronized propagated wave
-high degree of variability
>positive, negative, biphasic or low amplitude

Question 11

Describe the R-R interval.

Answer 11

-time between one R wave & next = cycle length
-evaluate regularity of heart beats (rhythm)
-calculate HR when the rhythm is regular

Question 12

Describe the ECG in large animals.

Answer 12

-variability in polarity & size of ECG waves
>variation
>cardiac depol pathways not consistent
-ECG not useful for diagnosing structural abnormalities
>EX: ventricular hypertrophy