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Questions and Answers
What is blood pressure defined as?
Define systolic pressure.
The maximum pressure that occurs throughout the cardiac cycle.
High blood pressure increases the risk of heart attack and strokes.
True
Define pulse pressure (PP) = ____________ - ____________
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Match the following blood pressure terms with their definitions:
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What is the main function of an Electrocardiogram (ECG)?
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How many standard limb leads are there in a normal ECG?
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Lead aVR is one of the 6 __________ leads in a standard ECG.
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The P wave on an ECG represents ventricular depolarization.
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Match the following ECG intervals with their descriptions:
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Study Notes
Cardiovascular System
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Blood pressure is the force exerted by the blood against any unit area of the vessel wall.
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Arterial pulse is the pressure wave that travels along the arteries due to the forcible ejection of blood into the arterial system during systole.
Blood Pressure
- Systolic pressure: The maximum pressure that occurs throughout the cardiac cycle.
- Diastolic pressure: The minimum pressure that occurs throughout the cardiac cycle.
- Pulse pressure (PP) = Systolic pressure (SP) - Diastolic pressure (DP)
- Mean pressure (MP) = Diastolic pressure + Pulse pressure/3
- Mean pressure is quite uniform in normal situations, but systolic and diastolic pressure may vary significantly throughout the arterial system.
Blood Pressure Abnormalities
- Physiological variations: Site of measurement, age, sex, body build, exercise, emotions, and meals.
- High blood pressure increases the risk of heart attack and stroke.
- Low blood pressure increases the risk of lower oxygen perfusion, e.g., in the brain.
Clinical Examination
- The classical sequence of clinical examination: Inspection, Palpation, Percussion, and Auscultation.
Measuring Arterial Pulse
- General rules:
- Limb should be supported and relaxed.
- Use three fingers.
- Compare bilaterally.
- Pulse sites:
- Head and neck.
- Upper limb.
- Lower limb.
- Data gained by arterial pulse examination:
- Rate.
- Form.
- Rhythm.
- Wall.
- Force.
- Volume.
Measuring Arterial Blood Pressure
- Brachial artery is located in the antecubital fossa, medial to the biceps tendon.
- Principle: Measuring the external pressure needed to occlude the vessel and stop blood flow.
- Methods:
- Palpatory Method.
- Auscultatory Method.
Palpatory Method
- Concept: Palpation of the radial artery while the cuff is wrapped around the brachial artery.
- Steps:
- Ensure necessary equipment.
- Wash hands with alcohol cleanser.
- Introduce yourself to the patient and explain the procedure.
- Patient position and sphygmomanometer.
- Cuff.
- Palpate the radial pulse and inflate the cuff until the pulse is no longer felt.
- Note the reading on the sphygmomanometer.
- Deflate the cuff completely.
Auscultatory Method
- Concept: Auscultate the brachial artery.
- Steps:
- Palpate the brachial artery.
- Place the stethoscope's diaphragm over the brachial artery.
- Listen carefully and note the reading on the sphygmomanometer.
- Re-inflate the cuff to 20-30 mmHg above the estimated systolic BP.
- Begin to slowly deflate the cuff and listen for the first Korotkoff sound (systolic pressure).
- Continue to deflate the cuff until the sounds disappear (diastolic pressure).
- Deflate the cuff and remove it.
- Measure the blood pressure in both arms to ensure the readings are similar.
- Document the recordings in the patient's notes.
- Explain the need for follow-up and thank the patient.
Important Notes
- Avoid undue rising of pressure in the sphygmomanometer with consequent pain.
- Palpatory method is used before auscultatory method to avoid the "auscultatory gap".
The Electrocardiogram (ECG)
- An important diagnostic tool, especially in rhythm disturbances, changes in electrical conduction, and myocardial ischemia and infarction.
Standard 12 ECG Leads
- 6 Limb Leads: 3 Bipolar (Standard Limb Leads) and 3 Unipolar Limb Leads
- 6 Chest (Precordial) Leads: V1 to V6
- The limbs leads are arranged to view the heart in the Frontal Plane
- The Chest leads are arranged to view the heart in the Horizontal (Transverse) Plane
ECG Leads Configuration
- Lead I: Right arm to left arm
- Lead II: Right arm to left leg
- Lead III: Left arm to left leg
- aVR: Exploring electrode in right arm, indifferent electrode in left arm and left leg
- aVL: Exploring electrode in left arm, indifferent electrode in right arm and left leg
- aVF: Exploring electrode in left leg, indifferent electrode in right arm and left arm
- V1: Right 4th intercostal space near sternum
- V2: Left 4th intercostal space near sternum
- V3: Midway between V2 and V4
- V4: Left 5th intercostal in mid-clavicular line
- V5: Left 5th intercostal in ant-axillary line
- V6: Left 5th intercostal in mid-axillary line
Conducting System of the Heart
- Typical transmembrane action potentials for the SA and AV nodes, other parts of the conduction system, and the atrial and ventricular muscles
- Correlation to the extracellularly recorded electrical activity, i.e., the ECG
Normal Spread of Electrical Activity in the Heart
- Depolarization wave: +ve wave
- Depolarization wave: -ve wave
- Repolarization wave: +ve wave
- Repolarization wave: -ve wave
ECG Waves and Intervals
- P wave: Represents atrial depolarization, starts 0.02 s before atrial systole, duration= 0.1s, amplitude= 0.1-0.3 mV
- QRS complex: Represents ventricular depolarization, starts 0.02 s before ventricular systole, duration= 0.04-0.12 s, amplitude= 1-2 mV
- T wave: Represents fast and strong ventricular repolarization, duration= 0.25 s, amplitude= 0.2-0.3 mV
- U wave: May be present, represents slow repolarization of papillary muscles
ECG Intervals
- P-R interval: 0.12-0.20 s, represents atrial depolarization and conduction through AVN
- S-T segment: 0.08 s, represents slow ventricular repolarization, should be isoelectric
- Q-T interval: 0.3-0.4 s, represents ventricular depolarization and repolarization, a measure of ventricular systole duration
Electrical Axis of the Heart
- The overall direction of depolarization which spreads throughout the heart
- Normally directed downwards and to the left of the subject
Abnormal Rhythms
- Respiratory sinus arrhythmia
- Sinus tachycardia
- Atrial fibrillation
- Ventricular fibrillation
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Description
Learn about the concepts of blood pressure, arterial pulse, systolic pressure, diastolic pressure, and pulse pressure in the cardiovascular system.
