health assessment draft

Cardiovascular Concepts

  • Assessment of Hemodynamic State

    • The space around the heart, known as the pericardial sac, protects the heart.

    • Abnormal sounds may be detected via stethoscope, originating from the heart or lungs.

The Cardiac Cycle

  • Initiation: Begins with the action potential from the sinus atrial node.

  • Contraction (Systole): Involves depolarization.

  • Relaxation (Diastole): Involves repolarization.

  • Prolonged Muscle Contraction:

    • Cardiac cells contain thousands of overlapping actin and myosin filaments.

    • A sarcomere is a structural unit (bounded by the sarcoplasmic reticulum) composed of these filaments.

    • Gap junctions allow rapid electrical signal transmission between cells.

    • Dermasomes facilitate force transfer between cells.

Blood Flow Mechanics

  • Blood enters the right atrium via the superior vena cava.

  • Veins assist blood flow in one direction; they do not create a pulse.

  • The tricuspid valve separates the right atrium and right ventricle.

    • During diastole, blood flows down from the right atrium to the right ventricle.

    • Right atrium depolarization pushes blood into the right ventricle.

    • Measuring pressure on the right side of the heart indicates right-sided heart problems.

  • Left Side of Heart: No valve at the entry to the left atrium.

    • The mitral valve is open during diastole, allowing blood to flow from the left atrium to the left ventricle.

Heart Sounds

  • Systolic Sound (S1): Caused by opening of the aortic valve and closure of the tricuspid and mitral valves; long and low-pitched.

  • Diastolic Sound (S2): Closure of the aortic and pulmonary valves; quick snap sound.

  • Third Heart Sound (S3): Abnormal, indicates rumbling of blood in an already full ventricle; more common in older adults.

Blood Pressure Basics

  • Blood pressure (BP) is pulsatile in elastic arteries near the heart.

  • Systolic Pressure: Pressure during ventricular contraction.

  • Diastolic Pressure: Lowest arterial pressure during the ventricular cycle.

  • Mean Arterial Pressure (MAP):

    • Calculated as (systolic + (diastolic × 2))/3.

Common Errors in Blood Pressure Measurement

  • Placing the cuff over clothing.

  • Using an incorrect cuff size.

  • A worn or serviced sphygmomanometer.

  • Arm not supported or elevated.

  • Failure to check both arms.

  • Patient not rested before measurement.

  • Patient talking during measurement.

  • Failure to palpate radial pulse before measurements.

  • Deflating cuff too quickly.

  • Re-inflating cuff before fully deflated.

  • Rounding off measurements.

  • Taking a single measurement.

Cardiac Output and Heart Function

  • Cardiac Output (CO): Volume of blood ejected from the ventricle every minute.

    • Calculated as CO = HR × SV; typically ~70 mL per beat, 70 beats per minute = 4900 mL/min.

  • Heart Rate (HR): Ranges from 40-170 bpm.

  • Stroke Volume (SV):

    • SV = End Diastolic Volume (EDV) - End Systolic Volume (ESV).

  • Preload: Refers to myocardial fiber stretch at the end of diastole.

  • Afterload: The pressure the heart must work against to eject blood.

  • Contractility: The ability of the heart muscle to contract.

Regulation of Blood Pressure

  • Control mechanisms affect the cardiovascular system:

    • Short-term: Baroreceptors in the carotid sinuses and aortic arch measure pressure.

    • Chemical receptors detect pH changes in blood, adjusting cardiac function as needed.

    • Negative feedback loops regulate pressure and flow, influencing heart rate and vascular resistance.

  • Rennin-Angiotensin System: Plays a crucial role in blood pressure regulation:

    • Involves blood volume and systemic vascular resistance.

    • Kidneys monitor pressure; low pressure leads to rennin release, creating angiotensin, a potent vasoconstrictor.