Cardiac

Question 1

+ve inotropy

Answer 1

Increases SV & systolic pressure.
Reduces RR interval. Affects stoke index.

Does NOT increase ventricular end diastolic pressure.

Question 2

Windkessel effect

Answer 2

Describe elastic force of aorta; the compressive force which occurs after LV systole & closure of Ao valve. Seen as dicrotic notch in arterial waveforms.

Question 3

Cannon a waves seen in

Answer 3

RA contraction against closed tricuspid valve:
Junctional rhythm.
AV block; esp 3rd degree.
VT.

Congenital heart blocks.
Constrictive pericarditis.
Pulm HTN.

Question 4

Y descent is due to

Answer 4

Opening of tricuspid valve and blood draining into RV.

Question 5

X descent occurs in

Answer 5

Ventricular systole: when blood leaves the ventricle.

Question 6

A wave correspondent in ECG

Answer 6

Corresponds to p wave. (Just after)

Question 7

Major determinants of myocardial oxygen consumption?

Answer 7

Ventricular wall tension.
Contractility.
Heart rate.

Question 8

Requirements of myocardial oxygen consumption?

Answer 8

Arterial & venous content (aortic root & coronary sinus), and est of total coronary flow

Question 9

Myocardial substrates for work other than O2

Answer 9

Glucose- 40% (insulin influence).
Fatty acids- 60%.
Ketones when conditions dictate.

Question 10

What is the O2 extraction ratio of the myocardium?

Answer 10

About 70%; pretty much maximum.

Blood returning to coronary sinus has PO2 <3kPa. Heavy on the aerobic metabolism.

Question 11

Stages of pressure-volume loop for LV includes:

Answer 11

1- Mitral valve opening - start of diastolic filling.

2- mitral valve closure at start of systole- isovolumetric contraction phase.

3- Ao valve opening at start of ejection phase.

4- Ao valve closure at start of isovolumetric relaxation phase.

Question 12

On LV pressure-vol loop, what are the effective work and the total work?

Answer 12

Effective work is the stroke work, which is represented by the area within the loop.

Total work is the effective work plus the potential energy (represented by area before stroke work when systolic & diastolic elastance curves are drawn)

Question 13

What are the determinants of stroke volume?

Answer 13

Preload (Starling’s law) & afterload (force opposing ventricular wall- tension).
Contractility (extrinsic influence e.g. calcium and sympathetic input).
Ventricular systolic & diastolic function (relaxation).

Question 14

Alternative equation for MAP?

Answer 14

MAP= (2/3 DBP) + (1/3 SBP)

Hence = DBP + (SBP-DBP)/3

Question 15

What are the determinants of myocardial oxygen consumption?

Answer 15

Primarily heart rate, contractility, and intra-myocardial tension. (Ventricular work)

Question 16

Normal ranges for oesophageal Doppler monitoring

Answer 16

CO 5-8L/min.
Stroke vol 55-100ml.
PV 70-100cm/sec.
FTc 330-360 msecs. (FTc: flow time corrected to HR 60bpm, so as to compare it more appropriately with other variables.)

Question 17

A fluid responsive patient under oesophageal Doppler monitoring should show…

Answer 17

Increased stroke vol/ stroke distance of >10% is seen as positive response; challenge should be repeated.

Failure to respond to fluid challenge should then be lead to inotropic agents consideration, and possibly vasodilators.

Question 18

Hypertrophy of the heart in athletes is similar to that in chronic hypertension?

Answer 18

True, but the athletic heart dose not demonstrate diastolic dysfunction.
Furthermore, SV can increase from 70ml to 140ml in trained male. (hence decreased resting heart rate to maintain same cardiac output). Max SV in training increases from 100 to 190ml in males.