Lt Lab: 1 Cardiac Cycle , ECG+ pulse ,ECG+ Heart Sounds, and Peripheral Circulation (DONE)

Describe the physiological events occurring in the heart muscle represented by each ECG component (the P wave, QRS complex, and T wave).

P Wave:

- atrial depolarization

QRS complex:

- ventricular depolarization, atrial depolarization happens at same time already, but is small and hidden by QRS

T wave:

- ventricular repolarization

define cardiac cycle (2)

events that occur from the beginning of one heartbeat to the beginning of the next

These events include changes in electrical and mechanical activity, and movements of the heart valves.

define diastole

apply to heart

"to dilate". Atrial and ventricular diastole refers to the relaxation of the myocardium in the atria and ventricles

define systole

apply to heart

to contract". Atrial and ventricular systole refers to the contraction of the myocardium in the atria and ventricles

When the terms systole and diastole are used on their own (without an "atrial" or "ventricular" prefix), they are referring to what?

they are referring to ventricular contraction and relaxation.

- when are heart valves closed

- phase name here

- volume here

when ventricles are alternating between periods of diastole and systole,

isovolumetric phase

volumes remains the same

how long for singe cardiac cycle

what HR?

0.8 seconds

75 bpm

what can affect the duration of the cardiac cycle (4)

- exercise

- medications

- hormones

- emotions

phases of cardiac cycle (6)

1. Atrial systole

- atria contracts forcing blood through the atrioventricular (AV) valves and into the ventricles.

2. Isovolumetric contraction (early ventricular systole)

- atria relaxes while ventricles contract

- Av valves are forced closed preventing backflow of blood

- semilunar valves remain closed

3. Ejection (later in ventricular systole)

- atria are still relaxed while the ventricles continue to contract.

- The AV valves remain closed, but increased ventricular pressure forces the semilunar valves open.

- Blood is forced into the aorta and pulmonary arteries.

4. Isovolumetric relaxation (early ventricular diastole)

- atria and ventricles relax.

- Pressure falls in the aorta and pulmonary arteries and the semilunar valves close (preventing backflow of blood into the ventricles).

- The atria begin to fill with blood but the AV valves are closed

5. Rapid filling (early to mid-ventricular diastole)

- atria and ventricles are relaxed

- ventricular pressure is now below atrial pressure and aortic (or pulmonary) pressure.

- The semilunar valves remain closed.

- The AV valves open and blood flows into the ventricles.

Which of the following events are associated with 'Systole" and which are with "Diastole"

- fall in ventricular blood volume

- rapid increase in aortic pressure

- rapidly increasing ventricular pressure

- P wave

- Second heart sound

Systole:

- rapidly increasing ventricular pressure

- rapid increase in aortic pressure

- fall in ventricular blood volume

Diastole:

- P wave

- Second heart sound

Systole includes which two stages of cardiac cycle?:

- Isovolumetric contraction and ejection

- Isovolumetric contraction and isovolumetric relaxation

- Isovolumetric contraction and rapid filling.

- Rapid filling and atrial contraction

- Isovolumetric contraction and ejection.

categorize following statements between either 'False' or 'True':

- Av and semilunar valves are never open at the same time during cardiac cycle

- When atria contract, the blood is forced into ventricles through open AV valves

- AV and semilunar valves are never closed at the same time during cardiac cycle

- Cardiac cycle begins with early ventricular systole

- The term "cardiac cycle" has the same meaning as "cardiac output"

True:

- Av and semilunar valves are never open at the same time during cardiac cycle

- When atria contract, the blood is forced into ventricles through open AV valves

False:

- AV and semilunar valves are never closed at the same time during cardiac cycle

- Cardiac cycle begins with early ventricular systole

- The term "cardiac cycle" has the same meaning as "cardiac output"

Which event of the cardiac cycle occurs immediately after the mitral valve closes? explain answer

- ejection

- IVCT

- IVRT

- rapid filling

Isovolumetric contraction:

- mitral valves area forced closed when the pressure in ventricle becomes greater than pressure in atrium

- After mitral valves close, pressure in ventricles rise rapidly as ventricle contract

- Volume remains constant as blood has nowhere to flow until aortic valve opens, when ventricle pressure exceeds that in aorta

The AV valves area forced closed when _____ pressure becomes ______ than _____ pressure

ventricular ; greater ; atrial

which phase of the cardiac cycle happens when aortic valves are open.... explain

ejection , when pressure in left ventricle exceeds that in aorta , pressure gradient forces valve open

during what phase of systole does the aortic valve remain closed? explain

isovolumetric contraction, ventricular pressure has not yet exceeded aortic pressure

match the following to the photo 1 (tablet):

- atrial contraction

- ejection

- isovolumetric contraction

- isovolumetric relaxation

- rapid filling

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T/F, the volume of blood received and ejected via the left ventricle is greater than the volume of blood received and ejected via the right ventricle... explain

false, the same volume of blood is received and ejected by both the left and right ventricles

T/F ,At the end of the ejection phase there is no blood remaining in the ventricles. Explain

False, at the end of the ejection phase there is 50-70ml of blood left in ventricles

on photo 2 (tablet) mentally draw a line within the range of the Pressure axis to show how ventricular pressure changes over time.

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During which phase does the left ventricular volume remain the same and the left ventricular pressure increase rapidly?

+ explain

isovolumetric contraction, means "equal volume" . Ventricular volume stays the same as both AV and semilunar valves are closed

Why is ventricular systolic pressure greater on the left side of the heart? ..Explain

To overcome the greater vascular resistance of the systemic circulation.

- the systemic circuit (which received blood from left side of heart) has greater total resistant than pulmonary circuit (right side)

Draw an aortic pressure line on the photo 3 (tablet)

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Draw an arrow to indicate where you think coronary blood flow will be greatest - draw on photo 3( - answers on photo 4

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what phase of cardiac cycle is coronary blood flow the greatest?

Isovolumetric relaxation (early ventricular diastole)

What happens to coronary blood flow when ventricular muscles contract and ventricular pressure rises... why?

As the ventricular muscle contracts and ventricular pressure rises, coronary blood flow falls abruptly.

- ventricular contraction compresses the vessels within the ventricular wall. this resistance in vessels rises and blood flow falls

on photo 5 match the following to the boxes of wiggers diagram:

- aortic pressure

- atrial pressure

- ventricular pressure

- ventricular volume

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END OF CARDIAC CYCLE>>>>>ECG AND PULSE

END OF CARDIAC CYCLE>>>>>ECG AND PULSE

ECG set up procedure (6)

1. Remove any jewelry from the volunteer's wrists and ankles.

2. Use a pen to mark a small cross on the volunteer's skin where each electrode will be placed (that is, both wrists and the right leg).

3. Lightly abrade the skin with abrasive gel, and clean the area with alcohol swabs.

4. Snap disposable electrodes onto the three electrode cables.

5.. Attach the electrodes to the following prepared areas on the volunteer's skin:

- Place the positive electrode on the left wrist.

- Place the negative electrode on the right wrist.

- Place the earth electrode on the right leg.

6. Ensure the finger pulse transducer is attached to a distal part of the volunteer's middle or index finger.

ECG exceuting procedure (6)

1. The volunteer should relax and sit as still as possible to minimize signal artifacts due to movements.

2. Enter the volunteer's name into the Comment panel.

3 Select Start to record, then select Add.

4. Use Auto Scale to see the data clearly in all channels.

5. After 60 s, select Stop. Leave the ECG cables and electrodes attached to the volunteer.

6.. Examine the ECG recording. Compare it to a model ECG recording.

Define the relationship between the ECG and the pulse wave. Explain why the timing of the QRS complex in the ECG and the start of the pulse wave do not coincide. (4)

- the electrical activity in the heart always precedes the mechanical contraction.

- This. there will be delay between R wave and ECG and the rising phase of pulse wave.

- Pulse wave takes a finite time to travel so the delay will be greater because we are measuring the pulse at the finger

- The time between the peak of R wave to start of the pulse upswing is sometimes referred to as the blood conduction time (rough estimate of time it takes for blood to travel from the heart to finger)

What events generate the P wave, QRS complex, and T wave?

- P wave is caused by depolarization of atrial cardiac muscle

- QRS complex is produced by depolarization of ventricular cardiac muscle (atrial repolarization also occurs during this time, but is hidden within ventricular signal

- T wave is produced by ventricular repolarization

What is the dicrotic notch, and why does it follow the T wave?

(3)

- T wave is the electrical event that corresponds with the repolarization of the ventricles. Since electrical activity in the heart precedes the mechanical event, T wave will always precede the relaxation of the ventricles

- Left side of the heart, blood is ejected out of left ventricle with force, causes increase in aortic pressure. When pressure in aorta becomes greater than that in ventricle. aortic valve closes

- dicrotic notch is a notch is a short-lived decrease in pressure in the ascending aorta, which occurs following closure of aortic valve. Blood that has just been pumped out of the left ventricle temporality flows back against the closed valve, which gives rise to the characteristic v-shaped notch in the pulse pressure wave. It can be used as a marker of the end of systole

ECG, reads what?

electrical activity occurring in atrial and ventricular muscles

for the ECG graph locate on photo 6

- PR interval

- QRS interval

- ST interval

- TP interval

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Milliseconds for the following ECG components:

- PR interval

- QRS interval

- ST interval

- TP interval

- 152 ms

- 68 ms

- 287 ms

- 728 ms

for ECG and pulse wave determine the peak of R wave to the start of the finger pulse upswing from photo 7

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Determine the time from the peak of the T wave to the dip after the peak of the pulse wave, which is known as the dicrotic notch from photo 7

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Dicrotic notch in pulse wave

small v-dip in downward slope of pulse waveform, representing the closure of aortic valve

END OF ECG+PULSE WAVE >>>>>START OF ECG++HEART SOUNDS

END OF ECG+PULSE WAVE >>>>>START OF ECG++HEART SOUNDS

for photo 8 label with the following:

- T

- Q

- P

- R

- S

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determine which of the following is ECG is a useful/ not useful tool for detecting?

- abnormal heart rate

- abnormal plasma sodium

- enlarged left ventricle

- ventricular arrhythmias

useful for:

- ventricular arrhythmias

- enlarged left ventricle

not useful for:

- abnormal heart valves

- abnormal plasma sodium

resting heart rate for a patient with tachycardia?

resting heart rate greater 100bpm is referred to as tachycardia

resting heart rate for a patient with bradycardia

resting heart rater less than 50 bpm is referred to as bradycardia

what may ventricular tachycardia lead to?

ventricular fibrillation

The heart's electrical conduction pathway gives rise to the QRS complex and the ECG tracing in general. Identify each component of the conduction system (photo 9)

- atrioventricular bundle

- bundle of His

- left bundle branch

- purkinje fibers

- right bundle branch

- sinoatrial node

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Which region of the heart generates electrical activity the fastest?

Sinoatrial node (SA)

Why is it important that there is slower conduction of the electrical signal through through the AV node (and its extension, the Bundle of His)?

The delay allows the atria to contract completely before ventricular contraction begins.

This image shows the temporal relationship between the pressure in the left ventricle (blue) and the heart sounds (orange). In terms of time and pressure, label where the valves open and close. (label on photo 10)

- aortic valve closes

- aortic valve opens

- atrioventricular closes

- atrioventricular opens

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auscultation

listening to sounds from the heart, lungs, or other organs, typically with a stethoscope, as a part of medical diagnosis.

what activity in the heart is associated with the first heart sound "lub", and what is associated with the second "dub"?

first heart sound "lub" occurs during early ventricular systole (isovolumetric contraction). Av valves close

Second heart sound "dub" occurs during early ventricular diastole (isovolumetric relaxation)

semilunar valves close

equipment set up for ECH activity of heart

Setup

Make sure the PowerLab is connected and turned on.

Connect the cardio microphone to Input 1 on the PowerLab. You will use it later in the lab.

Connect the finger pulse transducer cable to Input 2 on the PowerLab. You will use this later in the lab.

Plug the Bio Amp cable into the Bio Amp connector on the PowerLab.

Connect the electrode cables to Earth, CH1 NEG, and CH1 POS on the Bio Amp cable.

Electrode placement

Remove any jewelry from the volunteer's wrists and ankles.

Use a pen to mark a small cross where each electrode will be placed on the volunteer's right and left wrists, and right leg. Lightly abrade the skin with abrasive gel, and clean the area with alcohol swabs.

Snap the electrode cables onto some disposable ECG electrodes.

Attach the disposable electrodes to the prepared areas on the volunteer's wrists and leg:

Place the positive electrode on the left wrist.

Place the negative electrode on the right wrist.

Place the ground electrode on the right leg.

Ask the the volunteer to relax and not move. This will minimize signal artifacts due to movement.

Select Start to record.

Enter the volunteer's name into the Comment panel, and select Add.

Use the Auto Scale or compression buttons to ensure that you can see the data as it is being recorded.

If the ECG cannot be seen, check that all the electrodes are correctly attached. If the signal is noisy and indistinct, make sure that the volunteer is relaxed. Consider using the alternative attachment positions.

Select Stop.

Select Start.

Ask the volunteer to open and close his or her hands, and then move both arms across the chest. Enter "ECG artifact" into the Comment panel, and select Add.

Select Stop.

Ask the volunteer to sit quietly then select Start.

Enter "resting ECG" into the Comment panel. When you have a signal without movement artifacts, select Add to enter the comment.

Select Stop.

Why does the QRS complex have the largest amplitude?

QRS is the largest because, muscle mass of ventricle is greater than that of atria, and ventricular depolarization occurs faster than ventricular repolarization

Draw a circle around the letter of the electrical wave (P, Q, R, S, or T) that immediately precedes the first heart sound then, draw circle around stage right after second heart sound. (photo 11)

first sound of heart occurs just after QRS, seconds sound occurs just after end of T wave

Why does the first heart sound occur after the QRS complex? (2)

QRS complex represents ventricular depolarization, meaning ventricular contraction -> increases pressure in ventricles

AV valves close when pressure in ventricle exceeds that of atrium

= first sound is closure of two AV valves

Why does the second heart sound occur after the T wave? (3)

T wave represents ventricular repolarization --> ventricular relaxation, ventricular pressure falls

when pressure of L ventricle falls below aorta, aortic valves close, when pressure in R ventricle falls below pulmonary artery, pulmonary valves close

= second heart sounds is closure of two semilunar valves

Describe the relationships between the first and second heart sounds, and the finger pulse. (2)

the finger pulse is delayed

Dicrotic notch in pulse waveform follows the second heart sound. Dicrotic is a decreases in ascending aortic pressure following closure of aortic valve. Blood just pumped out of L ventricle flows back against closed valve, gives rise to V-shaped notch in pulse pressure wave (sometimes marks end of systole)

Match the description of the murmur to the valvular lesion:

(photo 12)

- Aortic stenosis

- Aortic regurgitation

- mitral regurgitation

- mitral stenosis

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END OF ECG + HEART SOUNDS>>>>>START OF PERIPHERAL CICRULATION

END OF ECG + HEART SOUNDS>>>>>START OF PERIPHERAL CICRULATION

Label the vessels below with the correct description. (photo 13)

- acts as a high pressure reservoir

- contain valve to stop back flow of blood

- drain blood from capillary beds

- exchange gases nutrients and waste

- high resistance vessels that regulate blood flow

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William Harvey

Harvey first described, correctly and in detail, the systemic circulation. He was the first to recognize that the heart pumped blood around the body.

direction of blood flow procedure (ignore)

Procedure

Place a blood pressure (BP) cuff around the upper arm and inflate this to a pressure of 90 mmHg.

You will observe what happens when parts of a vein are blocked and the blockage then released and when blood is stroked along the vein.

Describe what you observed with the arm held up above the head. Can you explain it?

- less blood in hand veins than there is is with the arm held down at side

= gravitational effect where pressures in vessels are below those in heart now

Health professionals are trained to assess various aspects of a pulse: the rate, rhythm, amplitude, and quality. For example, the rate might be 72 beats per minute, rhythm regular or irregular, amplitude full, and quality "thready" or collapsing. Which of these parameters do you think would be easy to assess, and which would be difficult?

- Amplitude

- Quality

- Rate

- Rhythm

Easy to assess:

- Rate

- Rhythm

Difficult to assess:

- quality

- amplitude

how to calculate own HR in bpm

counting the number of pulses in 30 seconds, then doubling this to give the number of pulses in 60 seconds (i.e., one minute) - easy!

While you do the next exercise, think about Mr Smith, a 53-year-old man who has noticed that at times he seems to have a "racing heart".

What might you learn from feeling his pulse? What pulse would you feel, where would you feel it, and what would you be commenting on?

- feel radial pulse at rest, easy to find, accessible

- look for rhythm, amplitude and quality (quality - does it rise slowly or rapidly and fall gradually or abruptly)

- rate of rise and fall give indications about state of aortic valve (ex: a stenosed "narrowed" valve results in a pulse greater than normal amplitude and rapid fall as blood flows back to heart from aorta through incompetent valve at beginning of ventricular relaxation (diastole)

Blood exhibits ____ flow through arteries and _____ despite what?

pulsatile ; arterioles

-> despite smoothing of pressure by elasticity of the major arteries

Palpation of arm arterial pulses - procedure (skip)

Feel the volunteer's or your own radial pulse, at the place indicated in the figure. You should feel it with the first three fingers (your index, middle, and ring fingers) placed in a line along the length of the radial artery.

Attempt to feel the volunteer's or your own ulnar pulse. In most people, no pulse can be felt.

Feel the brachial pulse at the elbow. This is the most common site to palpate the pulse in children.

tips for palpating arterial pulses (3)

1. Don't use your thumb for palpation - because the thumb has a strong pulse, you may end up feeling your own pulse rather than the volunteer's.

2. Don't press too hard - only light to moderate pressure is needed to feel a pulse.

3. Take your time - when feeling for arteries, it's best to glide the fingers back and forth slowly over the region rather than immediately applying pressure.

sites for palpation for arm arterial pulses (3)

brachial artery

radial artery

ulnar artery

Anatomical sites where a pulse can be palpated often correspond to "pressure points" for stopping hemorrhage in first-aid treatment. Why?

these points are where the arteries are closest to the skin, and close to bone, which serve as an excellent surface on which to compress the artery

In the video from the previous page, Nurse Bernie counts the pulse for 15-30 seconds. Comment on whether this differs from what you have been taught.

regional differences in what is taught about this. For example: in UK, pulse is taken for full 60 seconds, in order to detect any rhythm irregularities. in other countries , 30 seconds is adequate

Use arrows to show 3 places where you think you might be able to palpate for pulses on the image 14

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Palpation of leg arterial pulses locations (4)

Posterior tibial pulse

Popliteal pulse

Dorsalis pulse

femoral pulse

Femoral pulse palpation

Locate the superior border of the pubis in the midline of the body; this is the uppermost part of the pubic superior ramus. Feel the anterior limit of the iliac crest. The femoral pulse lies midway between these two bony points (the mid-inguinal point).

Popliteal pulse palpation

Ask the volunteer to bend the knee so that it is flexed to about 90°. Gently clasp the sides of the knee (of either limb) and press the pulps of your fingers into the popliteal fossa.

Dorsalis pedis pulse palpation

Place your fingers half way down the dorsum of the foot on the bony area (navicular and the intermediate cuneiform bones) in the line between the first and second toes. To help locate this area you can get your volunteer to dorsiflex their big toe and, using your fingers, follow the tendon up to the bony area. Roll your fingers laterally to find the pulse.

which region of pulse palpation of the leg can be easily lost if pushed to hard?

Dorsalis pedis pulse

Posterior tibial pulse palpation

Locate the medial malleolus. The posterior tibial pulse is 2-3 cm below and behind it. Because the artery is slightly deeper than the dorsalis pedis you will need to concentrate hard to find it.

Try this at home book + abdomen fun experiment

At home, lie down, relax your abdominal muscles and press deeply in the midline. You should be able to feel your abdominal aorta pulsating.

Place a book on your abdomen. You will probably see the book "bouncing" with each beat of your heart as the aortic pulse is transmitted through the wall of the abdomen to the book.

recording pulses with machine (skip) - radial

Palpate for the radial pulse on your volunteer. Place the pressure pad of the pulse transducer against the radial artery of a volunteer.

Use a Velcro strap to attach it firmly to the volunteer's wrist.

Connect the pulse transducer cable to Input 1 on the front of the PowerLab.

Check the PowerLab is connected to the computer and turned on.

In a clinical setting, why is it advisable to record the heart rate for 60 seconds rather than for a shorter duration, such as 15 or 30 seconds?

patient my have irregular heart beat, which could be missed if recording for just 15 or 30 seconds. Recording for 60 seconds gives you more accurate estimation of heart rate, and is necessary if the patient has an irregular heart rate

Arterial anastomoses

connections between arteries supplying the same tissues or organ

Arterial anastomoses procedure machine (skip)

Move the pulse transducer to the distal segment of a volunteer's middle finger.

Prepare the comment: "brachial".

Start recording.

Add the comment and apply firm pressure with the ball of the thumb over the brachial artery.

Prepare the comment: "release".

After 5-10 s, release the pressure on the artery and Add the comment.

Repeat steps 2-6 for the radial artery and then the ulnar artery.

Stop recording and observe your data. The waveforms should look similar to those in this figure.

Arterial anastomoses analysis:

- What effect did compression of each artery have on the finger pulse? What do you conclude from your results?

finger pulse was relatively unaffected when either radial or ulnar arteries were compressed. Compression of brachial artery, however largely abolished the finger pulse.

= palmar arches are supplied by both radial and ulnar arteries and loss of one arterial supply is compensated for by the other

A 37-year-old gentleman is anxious that his hand will be damaged by the loss of part of its blood supply. From what you learnt in this exercise, what could you tell him?

since the blood supply to the hand is shared between the radial and ulnar arteries through superficial palmar arch and deep palmar arch, blockage to radial artery would have small effect on circulation in hand

= should not result in major problems