| Question | Answer |
| Two main systems | left and right |
| The left coronary artery (LCA) branches into: | • Left Anterior Descending (LAD) -feeds anterior wall of LV, IVS, apex of heart
• Left Circumflex (LCx) -feeds lateral and posterior portion of LV |
| Right system | Right Coronary Artery (RCA) -feeds inferior wall of RV |
| The largest vessels in the body are | Arteries and Veins |
| The exchange of blood occurs at | Capillary level |
| • The spinal cord is posterior to the heart? | True |
| Arteries have small valves inside them to assist in the movement of
flow back to the heart? | False |
| Sinoatrial (SA) Node | - located at the right atrial wall; inferior to opening of SVC,
- Has the highest degree of “automaticity”
- Native “pacemaker” of the heart |
| Internodal Pathways | -Three: Anterior, Middle, Posterior - Feeds RA
- Bachmann’s Bundle – Feeds LA |
| AV Node and Bundle of His | - Connections of atria to ventricles;
- impulse slows for about .05 seconds to allow for ventricular filling |
| Bundle Branches | - Right and Left bundle branches; Right feeds RV, Left feeds LV |
| Purkinje fibers | - Penetrates into the ventricular muscle,
- rapidly conducts action potential to ventricles |
| Normal Intracardiac Pressures | RA – mean of 5 mmHg
RV – 25/5 mmHg
PA – 25/10 mmHg
LA – mean of 10 mmHg
LV – 120/10 mmHg
AO – 120/80 mmHg |
| P wave | represents atrial depolarization (discharge), followed immediately by atrial
systole (contraction) |
| QRS Complex | represents ventricular depolarization (discharge), followed
immediately by ventricular systole (contraction) |
| T wave | represents ventricular repolarization (recharge) |
| Isoelectric line | represents no conduction or contraction |
| R to R interval | represents 1 complete cardiac cycle |
| 1 cardiac cycle includes two phase… | Systole and diastole |
| R – R represents | 1 complete cardiac cycle |
| Ventricular contraction | Ventricular Systole |
| Ventricular Systole
ECG timing: | Closure of the AV valves to closure of the SV valves
Defined from the R wave to the end of the T wave |
| Ventricular Systole
Includes 3 phases | Isovolumic contraction phase (time)
Rapid ejection
Reduced ejection |
| Isovolumic Contraction Period/Time (IVCT) | Period begins at atrioventricular (AV) valve closure (enddiastole) and continues until semilunar (SL) valve opening |
| Iso
volumic | equal
volume |
| Isovolumic Contraction Period/Time | Heart volume is at its largest
No volume change because all valves are closed during this period
Duration: Valves are closed for a split second
Pressure rises rapidly in preparation for SL valve opening |
| Rapid Ventricular Ejection | Occupies the approx. first half of systole
SL Valves open
Rapid ejection of blood
Ventricular volume rapid decreases |
| Reduced Ventricular Ejection | Ventricular pressure begins to decline
Repolarization (recharging) occurs (on the T wave) |
| Ventricular Diastole | Ventricular filling
Closure of the SL valves to closure of the AV valves. |
| Ventricular Diastole
ECG rhythm timing: | Defined from the end of the T wave to the R wave |
| Ventricular Diastole
Includes 4 phases | Isovolumic relaxation phase (time)
Early rapid filling
Diastasis
Late filling |
| Isovolumic Relaxation Time/Period (IVRT) | Period begins at semilunar (SL) valve closure (endsystole) and continues until atrioventricular (AV) valve
opening |
| Isovolumic Relaxation Time/Period IVRT | Heart volume is at its smallest
No volume change because all valves are closed during this
period
Duration: Valves are closed for a split second
Pressure decreases rapidly in preparation for AV valve
opening |
| Stroke Volume (SV) | Volume of blood pumped out of
the ventricles during systole (per
heart beat |
| SV timing | SL valve opening-toclosure ( upstroke of S wave to
end of T wave) |
| SV measurements | Measured in milliliters (mL’s) or
cubic centimeters (cc’s |
| SV normal range | 70 – 100 mL/
heart beat |
| Frank-Starling Law | The greater the volume of blood in the heart during diastole
(filling), the more forceful the contraction, the more blood the
ventricle will pump |
| Frank-Starling Law normal volume/pres
relationship | Stroke volume ~ 75 mL/beat (changes with
heart rate)
LVEDP ~ 8 mmHg |
| Frank-Starling Law | Increase venous return = increased LVEDP
= increased preload = increased SV and
vise versa |
| SV Calculations | End diastolic volume (EDV) – End systolic volume (ESV) |
| Four Determinants of Left Ventricular Function | Heart Rate
Preload
Afterload
Contractility |
| Heart Rate | (chronotropic) |
| Heart Rate expressed as | beats per minute (BPM) |
