MaryANN HoGAN MedSurg. Nursing Chapter 25 Principles

cardiac output

Amount of blood pumped by each ventricle in liters per minute

Pparasympathetic and sympathetic divisions of the autonomic nervous system.

Balance between two reflex control systems normally determines the heart rate.

6 P's

Neurovascular Status

Principle:

Postural hypotension is likely in the setting of a decrease in pre-load which decreases cardiac output

Contractility

Strength of contraction regardless of preload ;decreased by hypoxia and some drugs (beta blockers and calcium channel blocker's )increased by the drugs (digoxin and dopamine)

apical impulse:

impulse normally palpated at the fifth intercostal space, left midclavicular line; caused by contraction of the left ventricle; also called the point of maximal impulse

states that create excessive volume ( heart failure, brady-arrhythmias) ,

you will notice increased preload. Therefore treating the underlying cause should result in alleviating the problem. If preload is low due to a volume issue volume can be added through fluids or blood. If preload is high due to poor pump function diuretics or alternative medication therapy might be considered.

*Baroreceptors are specialized nerve cells located

•aortic arch ,both right and left internal carotid arteries (at the point of bifurcation from the common carotid arteries).

Compensatory mechanisms attempt to decrease the BP through vasodilation and decrease heart rate.

•baroreceptors are sensitive to changes in blood pressure (BP). During significant elevations in BP (hypertension), cells increase their rate of discharge, transmitting impulses to the cerebral medulla; initiating parasympathetic activity and inhibits sympathetic response, lowering the heart rate and the BP.

hypotension

: a decrease in blood pressure to less than 100/60 mm Hg that compromises systemic perfusion

contractility

Ability of the cardiac muscle to shorten in response to an electrical impulse

Perfusion Fluid Volume

Changes in fluid volume effect blood volume and contributes to hypotension or hypertension (Page #668)

Postural hypotension (orthostatic hypotension)

Normal postural responses that occur when a person moves from a lying to a standing position include (1) a heart rate increase of 5 to 20 bpm above the resting rate; (2) an unchanged systolic pressure, or a slight decrease of up to 10 mm Hg; and (3) a slight increase of 5 mm Hg in diastolic pressure.

Postural hypotension (orthostatic hypotension)

accompanied by dizziness, lightheadedness, or syncope.

Ejection Fraction (EF)

less than 40% is indicative of impaired left ventricular function (Page #660)

IV fluid bolus and Norepinephrine

(a vasoconstrictor) will increase venous return to the heart and increase preload.

acute coronary syndrome

: a constellation of signs and symptoms due to the rupture of atherosclerotic plaque and resultant partial or complete thrombosis within a diseased coronary artery; leads to unstable angina or acute myocardial infarction

Vasodilators

Nitroglycerin will dilate vessels, which will decrease venous return to the heart and this will decrease preload. Furosemide is a diuretic which will remove extra fluid from the body via the kidneys. This will decrease venous return to the heart and decrease preload

11. Gas Exchange

Wheezing is a sign of lower airwary narrowing (Page #674) Crackles is a sign of fluid accumulation typically auscultated in the lower basis of the lungs (Page #674) Hypertension Hypertension consists of having a blood pressure greater than or equal to 140/90 (Page #667) Myocardial Infarct Myocardial ischemia or infarct may occur with blockages or constriction of coronary arteries! (Page #657) Unresolved ischemia leads to necrosis of myocardial cells and the release of enzymes (creatine kinase, CK-MB) and proteins (troponin T, troponin I and myoglobin) into the blood stream (Page #675) Organ Function Deoxygenated blood leaves the right side of the heart through the pulmonary artery and carbon dioxide diffuses into the alveoli while oxygen diffuses into the pulmonary capillary and is brought back to the left side of the heart via the pulmonary veins (Page #655) Blood flow to the right atrium is done through the inferior and superior vena cava (Page #655) The sinoatrial (SA) node initiates the impulse that causes atrial contraction which is observed by a p wave on the electrocardiogram (EKG) (Page #657) Impaired cardiac conduction between the sinoatrial node, atrial ventricular node, bundle of His, right and left bundle branch and the Purkinje fibers contributes to dysrhythmias (Page #658) Depolarization results in cardiac contraction while repolarization results in the return of the chambers to a resting state (Page #658) The total amount of blood that leaves the ventricles in one minute makes up the cardiac output (4-6 liters) (Page #659) Disorders that impair the heart rate or stroke volume will affect cardiac output (Page #659) Stroke volume on average is between 60 - 130 mililiters (Page #659) Stimulation of the parasympathetic nervous system results in vagal nerve innervation and a slowing of the heart rate (Page #659) Impaired preload, afterload or contractility effects stroke volume and cardiac output (Page #659) The greater the stretch of the myocardium the greater the force of the contraction (until elasticity is impaired) (Page #660) Medications that impair venous return could lead to a reduced preload and a decrease in cardiac output (Page #660) A decrease in pulse pressure (< 30 mm Hg) suggests a decrease in stroke volume and cardiac output while an increase in pulse pressure increases stroke volume and cardiac output (Page #668) S1 sound is the closing of the atrioventricular valves while S2 is closing of the pulmonic valves (Page #671) A decrease in urine output could suggest impaired cardiac function and renal perfusion (Page #674) The blood urea nitrogen and creatinine test are done to monitor renal function (Page #676) Alterations in perfusion is caused by impaired blood volume, pump disorders or vascular disorders (Page #681) Hemodynamic monitoring is performed in the intensive care unit and allows for direct monitoring of the cardiovascular system (Page #686) Elevated central venous pressure provides a measurement of the volume of blood that returns to the right side of the heart (2-6 mm Hg) so high levels could suggest heart failure while low levels could suggest dehydration or overdiuresis (Page #687) Safety Straining with bowel movements could trigger the Valsalva maneuver which increases intrathoracic pressure, decreases venous blood flow to the heart and results in a decrease in cardiac output (rebound phenomenon ensues) (Page #665) Change the patients position slowly to prevent orthostatic hypotension (Page #668) Keep the head of the bed elevated to 45 degrees following a transesophageal echocardiography and note gag reflex (Page #680) Deflate the balloon following pulmonary artery wedge pressure readings to restore blood flow through the pulmonary artery! (Page #688)

summation gallop:

abnormal sounds created by the presence of an S3 and S4 during periods of tachycardia

B. increase, increasing preload

4. A patient with hypovolemic shock is given IV fluids. IV fluids will help _________ cardiac output by:* A. decrease; decreasing preload B. increase, increasing preload C. increase, decreasing afterload D. decrease, increasing contractility

Bradycardia

Heart rate less than 60 bpm

Hypertension

Hypertension consists of having a blood pressure greater than or equal to 140/90 (Page #667)

shock, hypotension, tamponade) you will also see decrease preload.

In states that lead to low volume

Cardiac cycle

One complete heartbeat includes two phases systole (ventricular contraction) and diastole (ventricular relaxation and filling).

orthostatic hypotension (postural hypotension)

Risk for falls is the most significant threat to safety.

Effect of Stroke Volume on Cardiac Output

Stroke volume is primarily determined by three factors: preload, afterload, and contractility.

ejection fraction:

percentage of the end-diastolic blood volume ejected from the ventricle with each heartbeat

Stroke volume

the amount of blood pumped by the left ventricle with each beat.

afterload

the amount of resistance to ejection of blood from the ventricle

B. The amount the ventricles stretch at the end of diastole.

1. Which statement below best describes the term cardiac preload?* A. The pressure the ventricles stretch at the end of systole. B. The amount the ventricles stretch at the end of diastole. C. The pressure the ventricles must work against to pump blood out of the heart. D. The strength of the myocardial cells to shorten with each beat. pumped out of the heart.

D. It's the pressure the ventricles must work against to open the semilunar valves so blood can be pumped out of the heart.

2. Select the statement below that best describes cardiac afterload:* A. It's the volume amount that fills the ventricles at the end of diastole. B. It's the volume the ventricles must work against to pump blood out of the body. C. It's the amount of blood the left ventricle pumps per beat. D. It's the pressure the ventricles must work against to open the semilunar valves so blood can be

A. Heart rate C. Stroke volume

3. What two factors are used to calculate cardiac output? Select all that apply:* A. Heart rate B. Blood pressure C. Stroke volume D. Mean arterial pressure

Stroke volume

5. ___________ is the amount of blood pumped by the left ventricle with each beat.* A. Cardiac output B. Preload C. Afterload D. Stroke volume

Preload Contractility Afterload

6. Stroke volume plays an important part in cardiac output. Select all the factors below that influence stroke volume:* A. Heart rate B. Preload C. Contractility D. Afterload E. Blood pressure

Nitroglycerin Furosemide

7. Which treatments below would decrease cardiac preload? Select all that apply:* A. IV fluid bolus B. Norepinephrine C. Nitroglycerin D. Furosemide

Decrease the patient's blood pressure and decrease cardiac afterload

8. A patient has a blood pressure of 220/140. The physician prescribes a vasodilator. This medication will?* A. Decrease the patient's blood pressure and increase cardiac afterload B. Decrease the patient's blood pressure and decrease cardiac afterload C. Decrease the patient's blood pressure and increase cardiac preload D. Increase the patient's blood pressure but decrease cardiac output.

Vasoconstriction Aortic stenosis Pulmonary Hypertension

9. What conditions below can result in an increased cardiac afterload? Select all that apply:* A. Vasoconstriction B. Aortic stenosis C. Vasodilation D. Dehydration E. Pulmonary Hypertension

preload

: degree of stretch of the cardiac muscle fibers at the end of diastole

Baroreceptors

: nerve fibers located in the aortic arch and carotid arteries that are responsible for control of the blood pressure

Heart Valves

Atrioventricular (tricuspid and mitral) and semilunar valves (pulmonic and aortic) create the heart sound "lub-dub" and maintain blood flow through the heart in one direction (Page #671) Valve disorders contribute to turbulent blood flow and heart murmurs (Page #673)

APTM 2245

Auscultate heart sounds over the aortic (second intercostal space just right of the sternum), pulmonic (second intercostal space just left of the sternum), tricuspid (4th intercostal space left of the sternum) and mitral valve (5th intercostal space midclavicular region) areas (Page #670)

Cardiac Output (CO) Principles

Auscultate the apical pulse (point of maximal impulse) at the intersection of the fifth intercostal and midclavicular line (Page #656) Hypoxemia( blood low in oxygen ) and acidosis suppress ( carbonic suppression) cardiac contractility and could lead to a decrease in stroke volume and cardiac output (Page #660) An ejection fraction( amount of blood pumped Via the LV) less than 40% is indicative of impaired left ventricular function (Page #660) Estrogen contributes to vasodilation and enhances coronary blood flow (with menopause estrogen levels decline, impaired vasodilation) (Page #660) Changes in cardiac output impairs level of consciousness (alert, lethargic, obtunded, stuporous, comatose) and mental status (orientation to person, place and time) (Page #662) Determine changes in arterial blood flow by assessing for pain, pallor, paresthesia(numbness), paralysis(muscle weakness), poikilothermia/polar, pulselessness and capillary refill (Page #667) Chronic reduction of oxygenation and nutrients to the skin results in hair loss, dry scaling skin, ulcerations and brittle nails (Page #667) The pulse pressure (systolic minus diastolic) is a reflection of the stroke volume and the cardiac output (Page #667) Changes in cardiac output impairs level of consciousness (alert, lethargic, obtunded, stuporous, comatose) and mental status (orientation to person, place and time) (Page #667) Assess pulses using light palpation (Page #669) Auscultate heart sounds over the aortic (second intercostal space just right of the sternum), pulmonic (second intercostal space just left of the sternum), tricuspid (4th intercostal space left of the sternum) and mitral valve (5th intercostal space midclavicular region) areas (Page #670)

Principles: Chemical Agents

Brain natriuretic peptide (BNP) triggers Na excretion and a decrease in volume. (Page #675) Brain natriuretic protein (BNP) levels increase as ventricular pressure increases in order to rid the body of excess fluid (Page #675) A brain natriuretic protein level > than 100 pg/mL suggests heart failure (Page #675) (Body's natural diuretic)

Angina pectoralis

Chest pain resulting from restricted bloodflow to the myocardium

Decreased Contractility of the heart

Contractility is depressed by hypoxemia, acidosis(CO2 -waste buildup in the blood and lack of O2 in the blood making the heart unable to pump), and certain medications (e.g., beta-adrenergic blocking agents such as metoprolol [Lopressor]).

Contrast Medium

Contrast medium is nephrotoxic and is contraindicated if the patient has allergies to iodine, shellfish, or seafood, is pregnant or has an elevated creatinine (Page #683

Preload

Degree of myocardial fiber stretch at end of ventricular diastole ;influenced by ventricular filling volume and myocardial compliance.

Organ Function

Deoxygenated blood leaves the right side of the heart through the pulmonary artery and carbon dioxide diffuses into the alveoli while oxygen diffuses into the pulmonary capillary and is brought back to the left side of the heart via the pulmonary veins (Page #655) Blood flow to the right atrium is done through the inferior and superior vena cava (Page #655) The sinoatrial (SA) node initiates the impulse that causes atrial contraction which is observed by a p wave on the electrocardiogram (EKG) (Page #657) Impaired cardiac conduction between the sinoatrial node, atrial ventricular node, bundle of His, right and left bundle branch and the Purkinje fibers contributes to dysrhythmias (Page #658) Depolarization results in cardiac contraction while repolarization results in the return of the chambers to a resting state (Page #658) The total amount of blood that leaves the ventricles in one minute makes up the cardiac output (4-6 liters) (Page #659)

Principle:

Determine changes in arterial blood flow by assessing for pain ,pallor , paresthesia ,paralysis, poikilothermia/polar and pulselessness and capillary refill

Depolarization:

Electrical activation of a cell caused by the influx of sodium into the cell while potassium exits the cell

Fluid Volume:

Grade pitting edema from 0 (absent) to 4+ (more than 8mm)

Cardiovascular Disease Principles

Instruct on low sodium, fat and cholesterol diets in the prevention and management of cardiovascular disease (Page #665) Instruct on low sodium, fat and cholesterol diets in the setting and/or management of cardiovascular disease (Page #665) *A body mass index of (25-30 )is overweight while less than (18.5 )is underweight and both findings could increase the risk for disorders (one pound is equivalent to 3500 calories) (Page #667) Cholesterol levels > 200 mg/dL increases the risk for coronary artery disease (Page #675) Substances (homocysteine) that damage the endothelial lining of afteries increase the risk for thrombus formation and lead to stroke, coronary artery disease and peripheral vascular disease (Page #675) Elevated C-reactive protein levels suggests inflammation (Page #675) Lead II and V1 provide the best visualization for atrial and ventricular depolarization respectively (Page #677) ST segment depression suggests myocardial ischemia while ST elevation suggests infarct (Page #677) Cardiac stress test is done with exercise or pharmacologic agents to determine the hearts ability to respond to increased oxygen demand (Page #679) The echocardiogram shows the direction of blood flow through the chambers, the heart size, shape, ventricular function and ejection fraction (Page #680) Cardiac catheterization is performed to diagnosis coronary artery disease and the extent of coronary artery occlusion. (Page #683)

If pulmonary vascular resistance or systemic vascular resistance is high

It will create an increased cardiac afterload.

Heart Failure

Jugular vein distention, peripheral edema, hepatomegaly, scrotal edema, shortness of breath, and crackles suggest increased pressure and filling volumes in the ventricles (fluid volume overload) (Page #662) S3 is a significant finding in older adults and may suggest heart failure! (Page #672)

myocardium

Muscle layer of the heart responsible for the pumping action of the heart

Myocardial Infarct

Myocardial ischemia or infarct may occur with blockages or constriction of coronary arteries! (Page #657) Unresolved ischemia leads to necrosis of myocardial cells and the release of enzymes (creatine kinase, CK-MB) and proteins (troponin T, troponin I and myoglobin) into the blood stream (Page #675)

Red box warning:

Oxygen administration may remove the stimulus of hypoxemia, and the patient develops "carbon dioxide narcosis" unless the situation is quickly reversed. Therefore, oxygen is given only with extreme caution.

systole

Period of ventricular contraction resulting in ejection of blood from the ventricles into the pulmonary artery and aorta

Preload Highs and Lows

Preload is essentially (in basic terms) a measure of volume status within the body. In states that lead to low volume (shock, hypotension, tamponade) you will also see decrease preload. In states that create excessive volume ( heart failure, brady-arrhythmias) , you will notice increased preload. Therefore treating the underlying cause should result in alleviating the problem. If preload is low due to a volume issue volume can be added through fluids or blood. If preload is high due to poor pump function diuretics or alternative medication therapy might be considered.

All have a role with influencing stroke volume

Preload, afterload, and contractility

Dysrhythmias

Premature ventricular contractions could trigger life threatening dysrhythmias! (Page #659) Therapeutic levels for warfarin (coumadin) when used for atrial fibrillation is an international therapeutic ratio of 2-3 (Page #676) Fatal dysrhythmias may occur following cardiac catheterization! (Page #683)

cardiac afterload:

Pressure the ventricles must work against to pump blood out of the heart by opening up through the semilunar valves. So, it's the pressure the ventricles must overcome to open the semilunar valves to push blood out of the heart.

(bifurcation output)Perfusion

Principle:Postural hypotension is likely in the setting of a decrease in pre-load which decreases cardiac output. Assessment Findings Definition: postural (orthostatic) hypotension: significant drop in blood pressure (20 mm Hg systolic or more or 10 mm Hg diastolic or more) after an upright posture is assumed

Afterload

Resistance that ventricles must overcome to eject blood into systematic circulation directly related to arterial blood pressure

murmurs

Sounds created by abnormal, turbulent flow of blood in the heart

Measuring Preload

That volume is measured as the pressure that it exerts on the walls of the ventricles in mmHg. There are two numbers that we can use to indirectly measure or estimate preload: CVP and PAOP CVP is central venous pressure and provides an indirect measure of the EDV in the right ventricle. This is a parameter that a nurse can view using a flowtrac or other system that allows this number to be viewed. PAOP is pulmonary artery occlusion pressure provides an indirect measure of the EDV in the left ventricle. This number can aid in evaluating preload status of the left side of the heart.

What is Afterload?

The best way to think of afterload is pressure. Essentially, afterload is the PRESSURE that ventricles must exert to open the semilunar (aortic/pulmonic) valves. Vessels distal to the ventricles exert a pressure due to vasoconstriction or vasodilation. This pressure maintains the valves closed. In order to open the valves a specific pressure within the ventricles must be reached . . . this pressure is the AFTERLOAD. This number is represented by SVR and PVR (systemic and pulmonary vascular resistance respectively).

What is Preload?

The best way to think of preload is as a volume. Essentially, preload is the VOLUME of blood in the ventricles at the end of diastole. This is termed End Diastolic Volume (EDV), thus at the very end of diasotole, if you look at that volume of blood sitting in the ventricles . . . that is your PRELOAD.

Principle:

The blood pressure represents the amount of pressure thats exerted on the walls of the arteries during systole and diastole and is influenced by cardiac output and peripheral vascular resistance (distention of the arteries) (Page #667)

increase stroke volume

The heart can achieve an(e.g., during exercise) if preload is increased (through increased venous return), if contractility is increased (through sympathetic nervous system discharge), and if afterload is decreased (through peripheral vasodilation with decreased aortic pressure).

high blood pressure effects on cardiac output:

The patient has a high systemic vascular resistance...as evidence by the patient's blood pressure blood....there is vasoconstriction and this is resulting in the high blood pressure. Therefore, right now, the cardiac afterload is high because the ventricle must overcome this high pressure in order to pump blood out of the heart. If a vasodilator is given, it will decrease the blood pressure (hence the systemic vascular resistance) and this will decrease the cardiac afterload. The amount of the pressure the ventricle must pump against will decrease (cardiac afterload decrease) because the blood pressure will go down (hence the systemic vascular resistance).

IV fluids will increase venous return to the heart.

This will increase the amount of fluid that will fill the ventricles at the end of diastole...hence increasing preload and increasing cardiac output.

echocardiogram

Use for Structure & Function, used for internal & External diagnosing

Stroke Volume (SV)

Volume of blood ejected each cardiac cycle.

Cardiac Output (CO)

Volume of blood in liters ejected by heart each minute; indicator of pump function of heart; normal adult CO is 4 to 8 L per minute cardiac output equal heart rate times stroke volume . CO=HRxSV

Preload is essentially (in basic terms)

a measure of volume status within the body.

cardiac stress test

a test used to evaluate the functioning of the heart during a period of increased oxygen demand; test may be initiated by exercise or medications

opening snaps:

abnormal diastolic sound generated during opening of a rigid atrioventricular valve leaflet

systolic click:

abnormal systolic sound created by the opening of a calcified aortic or pulmonic valve during ventricular contraction

stroke volume:

amount of blood ejected from one of the ventricles per heartbeat

S3

an abnormal heart sound detected early in diastole as resistance is met to blood entering either ventricle; most often due to volume overload associated with heart failure

S4

an abnormal heart sound detected late in diastole as resistance is met to blood entering either ventricle during atrial contraction; most often caused by hypertrophy of the ventricle

Homocysteine:

an amino acid normally present in the blood that, when found at high levels, may be related to higher risk of cardiovascular disease.

cardiac catheterization:

an invasive procedure used to measure cardiac chamber pressures and assess patency of the coronary arteries( Structure & Function)

afterload is increased by

arterial vasoconstriction, which leads to decreased stroke volume. Opposite is true with arterial vasodilation, in which case afterload is reduced because there is less resistance to ejection, and stroke volume increases.

Assess for cardiac output

assess pulses using light palpation signs of changes in arterial blood flow ❶ pain ❷ pallor ❸ paresthesia ❹ paralysis ❺ poikilothermia/polar ❻ pulselessness ❼ capillary refill

myocardial ischemia:

condition in which heart muscle cells receive less oxygen than needed

orthostatic hypotension (postural hypotension)

creates a significant risk for falls due to the dizziness and lightheadedness that accompanies it. Ability to perform normal roles may be affected.

Aortic stenosis

creates an outflow of blood obstruction for the ventricle (specifically the left ventricle) and this will increase the pressure the ventricle must pump against to get blood out through the aortic valve.

Postural hypotension (orthostatic hypotension)

drop in blood pressure related to change in position (supine/seated to standing), caused by pooling of blood in the veins, decrease in venous return, and decreased cardiac output

Cardiac output is calculated by taking the

heart rate and multiplying it by stroke volume. CO = HR x SV

Sympathetic Nervous System (SNS)

increases heart rate by innervation of the beta-1 receptor sites located within the SA node. The heart rate is increased by the sympathetic nervous system through an increased level of circulating catecholamines (secreted by the adrenal gland) and by excess thyroid hormone, which produces a catecholamine-like effect.

Pulmonary hypertension

increases pulmonary vascular resistance which will increase the pressure the right ventricle must overcome to open the pulmonic valve to get blood out of the heart....all of this increase cardiac afterload.

Heart rate

is affected by central nervous system and baroreceptor activity.

afterload

is the PRESSURE

Cardiac preload

is the amount the ventricles stretch at the end of diastole (the filling or relaxation phase of the heart).

If pulmonary vascular resistance or systemic vascular resistance is low,

it will create a decreased cardiac afterload.

Cardiac output responds to changes in the

metabolic demands of the tissues associated with stress, physical exercise, and illness. To compensate for these added demands, the cardiac output is enhanced by increases in both stroke volume and heart rate.

diastole:

period of ventricular relaxation resulting in ventricular filling

sinoatrial (SA) node:

primary pacemaker of the heart, located in the right atrium

: unstable atoms that give off small amounts of energy in the form of gamma rays as they decay; used in cardiac nuclear medicine studies

radioisotopes

Contractility of the heart

refers to the force generated by the contracting myocardium.

pulmonary vascular resistance:

resistance to blood flow out of the right ventricle created by the pulmonary circulatory system

Vasoconstriction increases systemic vascular

resistance which will increase cardiac afterload. It will increase the pressure the ventricle must pump against to open the semilunar valves to get blood out of the heart.

Increased Contractility of the heart

results in increased stroke volume. Enhanced by circulating catecholamines, sympathetic neuronal activity, and certain medications (e.g., digoxin [Lanoxin], dopamine, or dobutamine).

atrioventricular (AV) node:

secondary pacemaker of the heart, located in the right atrial wall near the tricuspid valve

normal heart sounds:

sounds produced when the valves close; normal heart sounds are S1 (atrioventricular valves) and S2 (semilunar valves)

cardiac conduction system

specialized heart cells strategically located throughout the heart that are responsible for methodically generating and coordinating the transmission of electrical impulses to the myocardial cells

Postural hypotension (orthostatic hypotension)

sustained decrease of at least 20 mm Hg in systolic BP or 10 mm Hg in diastolic BP within 3 minutes , heart rate of more than 20 bpm above the resting rate of moving from a lying or sitting position to a standing position.

pulse deficit:

the difference between the apical and radial pulse rates

S1:

the first heart sound produced by closure of the atrioventricular (mitral and tricuspid) valves

telemetry

the process of continuous electrocardiographic monitoring by the transmission of radio waves from a battery-operated transmitter worn by the patients .

S2:

the second heart sound produced by closure of the semilunar (aortic and pulmonic) valves

hemodynamic monitoring

the use of pressure monitoring devices to directly measure cardiovascular function

Branches of the parasympathetic nervous system

travel to the SA node by the vagus nerve. Stimulation of the vagus nerve slows the heart rate.

Compensatory mechanisms attempt to elevate the BP through vasoconstriction and increased heart rate.

•opposite during hypotension (low BP). Less baroreceptor stimulation during hypotension prompts a decrease in parasympathetic activity and enhances sympathetic responses