Cardiovascular Disorders & Medications: Blood Pressure

Cardiovascular System

• Heart

• Blood Vessels

• Lymphatic System

• Blood

• 1st heartbeat 4 weeks after conception until death

• 100,000 beats per day

• Pumps blood through ~50,000 miles of vasculature

Basic Structures of the Heart

2 collecting chambers

 R atria

 L atria

1 low pressure pump

 R ventricle

1 high pressure pump

 L ventricle “WORKHORSE”

4 valves preventing reflux

 Tricuspid

 Pulmonic semilunar

 Mitral (bicuspid)

 Aortic semilunar

Calculating Cardiac Output

Stroke volume (SV) = amount of blood pumped out of ventricle in a single beat.

~ 60 to 130 mL

3 components

1. Preload

2. Afterload

3. Contractility

Cardiac output (CO) = amount of blood pumped out in a minute

Normal CO is - L/min in the adult

CO= _ x SV

Stroke Volume Components

Preload - Volume

• Volume of blood in ventricles at end of diastole

• (Frank Starling Law)

• vasodilation/constriction and increase blood volume

Afterload – Pressure or Resistance

• Resistance L ventricle must overcome to circulate blood (Squeeze)

• Increase afterload = increase cardiac workload

Contractility

• Force with which the heart contracts

Blood Pressure

__systolic_ Blood Pressure: the peak pressure, produced by the contracting ventricles

__diastolic___ Blood Pressure: the pressure in your arteries when the ventricles are relaxed

• Systole MINUS diastole = pulse pressure

• Pulse pressure = force generated during systole

• Mean Arterial Pressure (MAP) = calculation of average pressure.

  • Should be 60 or greater

Better indicator of tissue perfusion - it accounts for the fact that two thirds of the cardiac cycle are spent in diastole

Hypertension

Risk Factors

• Age

• Race (AA)

• Family hx

• Overweight or obese

• Inactivity

• Tobacco use

• High sodium, low K diet

• ETOH – more than 3 drinks in a sitting

• Stress

Complications

• Atherosclerosis

• Aneurysms

• HF

• CVA

• Hypertensive crisis

• Renal damage

• Vision loss

Diagnosis

• Consistent SBP >120 0r DBP > 80 is elevated BP

• Heart is working harder than normal to pump

• Primary or Essential HTN has no identifiable cause, insidious onset. Risk factors play a huge role here.

• Secondary HTN develops d/t underlying condition (chronic kidney disease, congenital heart defects, meds, drugs)

• If present, clinical manifestations may include dizziness, fatigue, headache, malaise, vision changes, chest pain

• Leading risk factor for cardiovascular disease

Hypertension Definitions

Normal

• Systolic less than 120

• and Diastolic less than 80

Elevated

• 120-129

• and Less than 80

Stage 1

• 130-139

• or 80-89

Stage 2

• 140 or higher

• or 90 or higher

Hypertensive crisis

• higher than 180

• and/or higher than 120

Hypertension Summary

• Can be idiopathic or due to underlying condition

• RAAS becomes maladaptive

• Risk factor for MANY, MANY conditions

• Patient may not know they have it

• Symptoms usually = organ damage

• Many modifiable risk factors

Hypertension Treatment

Treatment

• Low salt 2,300mg/day

• Increase fruit, veg, FF dairy, whole grains, fish, beans, seeds

• Minimize sweets & red meats, cholesterol, & total fat

• Lose weight

• Activity

• Stop smoking, manage stress

• Reduce ETOH use/ Illicit drugs

Treatment - Pharm

• Diuretics

• β-adrenergic blocking drugs

• Angiotensin-converting enzyme (ACE) inhibitors

• Angiotensin II receptor blockers

• Calcium channel blocking drugs

• Central α2-adrenergic agonists

• α1-Adrenergic receptor blockers

• Vasodilators

RAAS Suppressors: ACE Inhibitors

Prototypes: captopril, lisinopril

Indication for Use

• Hypertension, Heart failure (in combo with other drugs), Diabetic neuropathy

Mechanism of Action

• Works in the lungs to prevent ACE from converting angiotensin I (inactive) to angiotensin II (active hormone)

• Result = drop in BP (slight increase in potassium)

• Decrease in cardiac WL due to decrease in SVR and BV

Adverse Drug Reactions

• Severe HTN first dose

• Reflex tachycardia

• Dry cough

• Angioedema

• Metallic taste, rash, neutropenia

• Hypersensitivity

Interventions/Nursing Actions

• Monitor for hypotension

• Monitor for angioedema

• Labs potassium/WBC’s

• Titrate dose up slowly

• Diuretics

• Antitussive for cough?

Client Instructions

• Watch for hypotension

• Empty stomach (captopril)

• S/Sx of hyper K+, infection

• Supine after first dose: dizziness

• No potassium supplements!!

• No salt substitutes! (general rule)

Contraindications

• Pregnancy and lactation

• Hyper K

Drug Interactions

• Any med that impacts potassium

• NSAIDs may render less effective

• Don’t combine with other RAAS suppressors

• *may have to dose adjust for ethnicity

Precautions

• Renal Impairment

• Immunosuppression

• Hx of heart disease, hyper k

• Cerebrovascular disease

RAAS Suppressors: Angiotensin Receptor Blockers (ARBs)

Prototypes: losartan, valsartan

Indications for Use

• Hypertension (all ARBs), stroke prevention (losartan only), Diabetic neuropathy (certain ones)

Mechanism of Action

• Blocks angiotensin II receptors

• Result = drop in BP (slight increase in potassium)

• Decrease in cardiac WL due to decrease in SVR and BV

Adverse Drug Reactions

• Hypotension

• Angioedema: receptors change swelling & fluid

• HA, insomnia

Interventions/Nursing Actions

• Monitor BP

• d/c if angioedema occurs

Client Instructions

• Take with or without food

• Monitor for swelling/angioedema

• Monitor BP

Contraindications

• Pregnancy/lactation

• < 6yo

• >6yo but low creatinine clearance

Drug Interactions

• NSAIDs reduce effectiveness

• If given with other hypotensive may have severe impact on HTN

Precautions

• Diuretics

• Hyper K+

• Hepatic impairment

• Renal impairment

Calcium Channel Blockers

Prototypes: nifedipine, amlodipine, diltiazem

Indications for Use

• HTN (and sometimes angina or cardiac dyrhythmias)

Mechanism of Action

• Inhibits movement of calcium across membranes of myocardial muscle or arterial muscle cells

• Alters action potential, decreases contractility, relaxes/dilates arteries

• Therefore, causing a drop in BP

Adverse Drug Reactions

• Reflex tachycardia

• CNS effects, dizziness syncope

• Peripheral edema

• GI issues

• Skin flushing

• Gingival hyperplasia

Interventions/Nursing Actions

• Anticipate beta blocker

• Monitor HR

• Assist with ambulation

• If systolic BP<90 mmHg hold

• Recommend regular dental exams

Client Instructions

• Watch for hypotension

• Watch for bradycardia

• Regular dental exams

• Don’t increase dose!

• Avoid Grapefruit juice

• Monitor for edema

Contraindications

• Pregnancy/Lactation (not known)

• Allergy

• 2nd & 3rd degree heart block

• Systolic pressure of <90 mmHg

Drug Interactions

• St. John’s Wart

• Grapefruit juice

• Cyclosporins

Precautions

• Geriatric population

• Reflux disease

• Heart failure

Sympatholytic: Alpha 1 Blockers

Prototypes: doxazocin

Indications for Use

• HTN (and symptomatic BPH)

Mechanism of Action

• Most Alpha 1 blockers are in the smooth muscle and cause vasoconstriction when activated by epi or norepi

• These medications block this vasoconstriction

Adverse Drug Reactions

• Orthostatic hypotension(esp 1st dose)

• Reflex tachycardia

• HA/Dizziness

Interventions/Nursing Actions

• Monitor for HR and BP 2-6h after

• Report change in BP >20 mmHg

• Report Headache

Client Instructions

• Take at bedtime

Contraindications.

• Allergy

• Hypotension

• Hx of syncope

• Children

Drug Interactions

• Sildenafil may increase hypotens

• Alcohol may increase hypotens

• NSAIDs decrease therapeutic effects

Precautions

• Geriatric Clients

• Hepatic disease

• Safety not established w/preg

Sympatholytic: Beta Blockers

Prototypes: atenolol, metoprolol, propranolol

Indications for Use

• HTN, angina pectoris, decrease mortality after MI, heart failure

Mechanism of Action

• Blocks beta receptors (selective B1 only, non-selective B1 and B2)

• Decreases heart rate, contractile force, impulse conduction, also decreases renin release in the kidneys

Adverse Drug Reactions

• Bradycardia

• May lead to reduced CO

• Heart failure

• Rebound excitation if not tapered

• Angina

Interventions/Nursing Actions

• *Monitor HR if less than 50, hold

• Teach pt not to stop abruptly

• Teach symptoms of heart failure

Client Instructions

• Report s/sx heart failure

• Report bradycardia (take pulse)

• Don’t stop abruptly

• Take same time each day

• Before meals or bedtime

• Report CP

Contraindications

• Sinus brady or > 1st degree heart block

• Moderate to severe HF

• Cardiogenic shock

• Raynaud’s disease

• Children under 6yo

Drug Interactions

• Digoxin (may have additive effect)

• Antacids may decrease absorption

Precautions

• Adrenal tumor

• Asthma (esp non-selective), COPD

• DM

• Depression

• Hyperthyroid

Sympatholytic: Alpha 2 Agonists

Prototypes: clonidine

Indications for Use

• HTN (severe pain - epidural injection, ADHD)

Mechanism of Action

• Activates the Alpha 2 receptors in the brainstem

• Results in sympathetic stimulation reduction of heart and vessels

• Decreased BP d/t passive vessel dilation

Adverse Drug Reactions

• Drowsiness, dizziness

• Dry mouth!

• HTN Crisis if d/c suddenly

Interventions/Nursing Actions

• Monitor for CNS effects

• Education about dry mouth (will improve after ~1mo)

• Must taper dose

• Might be patch route

• Monitor for abuse potential

Client Instructions

• Take at night

• Don’t drive

• Hard candy (esp sour)

• Don’t suddenly stop

• Rotate patch sites if applicable

Contraindications

• Anticoagulation therapy (can increase risk for bleeding)

• Severe heart disease

Drug Interactions

• Alcohol, opioid, diphenhydramine

• All increase CNS depression

• MAOI, amphetamines, or

• Antidepressants may reduce therapeutic effects.

Precautions

• Cerebrovascular disease

• Renal disease

• Abuse potential

Sympatholytic: Alpha/Beta blockers

Prototypes: carvedilol

Indications for Use

• HTN, post MI, heart failure (in combination with other drugs)

Mechanism of Action

• Block both Alpha 1 (body) and Beta 1 (heart)

• Alpha 1 block is responsible for dilation of arteries

• Beta 1 block is responsible for decreased heart rate and contractile force

Adverse Drug Reactions

• Dizziness/HA

• Hypotension

• Bradycardia

• Decrease CO

• Orthostatic hypotension

• Asthma!

Interventions/Nursing Actions

• Monitor HR; report if less than 60

• How do you measure HR?

Client Instructions

• Take with food to minimize orthohyp

• Report dizziness or syncope

• Move slowly and don’t drive

• Check heart rate

Contraindications

• Pregnancy/Lactation

• Bronchospastic resp disorder (non-selective)

Drug Interactions

• Insulin or oral hypoglycemic

• Carvedilol will alter effectiveness

Precautions

• Under 18

• DM or renal disease

• Hepatic disease

• Peripheral vascular disease

Direct Acting Vasodilators

Prototypes: hydralazine

Indications for Use

• HTN, Hypertensive Crisis

Mechanism of Action

• Dilates arterioles which decreases peripheral vascular resistance (PVR)

• This drops arterial pressure without changing venous pressure

Adverse Drug Reactions

• Reflex tachycardia (most common)

• SLE-like disorder (systemic lupus)

• HTN crisis if d/c quickly

Interventions/Nursing Actions

• Monitor HR (tachy)

• Monitor s/sx of SLE-like syndrome

• Crackles in lungs (might need diuretic)

• Anticipate titrating

Client Instructions

• Report HA

• Move slowly, don’t drive *

• Watch for reflex tachycardia

• Monitor for s/sx of SLE-like syndrome

• Must taper!

Contraindications

• Sensitivity

Drug Interactions

• NSAIDs decrease effects

• Antidepressants/MAOI’s increase

• Other hypotensives

Precautions

• CV disease

• Cerebrovascular disease

• Renal/hepatic impairment