Question

Help please!

Assuming an EDV of 130ml and an ESV of 50ml use the obtained blood pressure values to carefully and accurately draw this individuals left ventricular pressure volume loop in as much detail as possible (think back to being in class). When annotating this picture you are expected to label x and y axis with appropriate titles and units and identify the key values, including blood pressure, on each axis. You must also use the "typing" function for labeling to receive credit. Annotate Start Over

Answer 1

150 Aortic Valve Closing 3 С 100 Aortic Valve Opening d LVP (mmHg) ESPVR SV 50 Mitral Valve bClosing Mitral Valve Opening a EDPVR 0 0 50 100 150 EDV ESV LV Vol (ml)

EXPLANATION:

Volumes:

• At the end of ventricular diastole (just before systole): EDV, i.e. 130 ml
• Volume remains same during isovolumetric contraction = 130 ml
• Rapid ejection phase = 70% of stroke volume is ejected, i.e. about 55 ml is ejected
• At the end of rapid ejection phase = 130-55 ml = 75 ml
• Remaining 25 ml is ejected during reduced ejection phase
• By the end of reduced ejection phase, we have End systolic volume (ESV) = 50 ml
• Volume remains same during isovolumetric relaxation = 50 ml
• 80% of ventricular filling (EDV) occurs before atrial contraction = rises to 105 ml
• Remaining 25 ml is filled by atrial contraction = EDV, i.e. 130 ml

Ventricular and aortic pressure changes: Let us talk focusing only the left side of heart –

1. At the end of atrial systole, ventricles are closed chambers with both the aortic and mitral valves closed. Isovolumetric ventricular contraction raises the ventricular pressure rapidly to 80 mmHg.
2. When ventricular pressure just exceeds 80 mmHg, the aortic valve opens and the “sloppy” pressure rise becomes more gradual. As the blood runs off into the aorta, the pressure in the aorta simultaneously rises with that of left ventricle upto 120 mmHg and falls upto 80 mmHg. Throughout this period, ejection of blood occurs:
   • 1/3rd of ejection period (pressure rises from 80 to 120 mmHg): rapid ejection occurs (70% volume ejection)
   • 2/3rd of ejection period (pressure falls from 120 to 80 mmHg): reduced or slow ejection occurs (30% volume ejection)
3. Once, the pressure approaches 80 mmHg, the elastic recoil of aorta overcomes falling ventricular pressure leading to closure of aortic valve and the ventricular pressure continues to fall down. Due to inertia of flowing blood, blood momentarily hits the closed aortic valve just after it’s closure giving rise to “incisura“.
4. Once again the ventricle is a closed chamber when the semilunar valve closes. During isovolumetric relaxation, there is “sloppy” fall in ventricular pressure to 10 mmHg and the aortic pressure is maintained in it’s diastolic pressure (80 mmHg) which ensures continuous perfusion of organs even during ventricular diastole.
5. When the mitral valve opens, there is rapid ejection of blood from atrium to ventricle – leading to fall in atrial pressure (end of “v” wave in JVP and beginning of “y” descent).
6. When the pressure in ventricle approaches that of atrium, they act as a single chamber and very little or no blood is filled into ventricle during this period and is known as “diastasis“. This is the longest period of diastole (about 0.2 seconds).