Pathophysiology - Lecture 13 - Cardio

Angina Pectoris

occurs when there is a deficit of oxygen to meet myocardial needs (ischemia)

3 different angina

-classic

-variant angina

-unstable angina

Classic (exertional) angina

-cold

-stress

Variant angina

-vasospasm occurs at rest

-Prinzmetal

Prinzmetal

-angina at rest

-drug use

Unstable angina

-prolonged pain at rest

-may precede MI

-Cx-atherosclerosis

-ER -> Cardiac Cath lab

What is Stable Angina Pectoris?

Recurrent, intermittent brief episodes of substernal chest pain.

What triggers Stable Angina Pectoris?

Physical or emotional stress.

How do the attacks of Stable Angina Pectoris change over time?

They become more frequent and longer as the disease progresses.

How is Stable Angina Pectoris relieved?

By rest and administration of coronary vasodilators.

Nitroglycerin

it's a coronary vasodilator that primarily acts by reducing systemic resistance, decreasing the demand for oxygen

Emergency tx for angina

-rest, stop activity

-pt seated in upright position

-admin of nitro sublingual

-administer oxygen

Patient known to have angina

second dose of nitroglycerin

patient without hx of angina

emergency medical aid

What happens to the coronary artery during a myocardial infarction?

The coronary artery is totally obstructed.

What is the most common cause of myocardial infarction?

Atherosclerosis.

What can obstruct the artery during a myocardial infarction?

A thrombus from an atheroma.

What is a less common cause of myocardial infarction?

Vasospasm.

What factors determine the damage caused by a myocardial infarction?

The size and location of the infarct.

Warning s/s of MI

-pressure, heaviness, burning in chest

-sudden SOB, weakness, fatigue

-nausea, indigestion

-anxiety and fear

-pain in substernal

-pain or crushing

-radiating L arm or L jaw

Dx of MI

-ECG

-cardiac troponin are elevated

-myosin are elevated

What are the two enzymes that are elevated during a heart attack?

CPK and cardiac troponin

Complication of MI

-sudden death

-cardiogenic shock

-CHF

-Rupture of necrotic tissue

-Thromboembolism

Thromboembolism

causes cerebrovascular accident (CVA; with left ventricular MI)

What are the 3 steps for treating MI?

-keep them alive

-stabilize them

-start therapy right away

Tx for MI

-reduce cardiac demand

-Oxygen therapy

-analgesics

-anticoagulants

-thrombolytic agents may be used to stop clotting

-tissue plasminogen activator to break up clot

Medication to treat which symptoms to prevent MI?

-Dysrhythmias

-HTN

-CHF

-Cardiac rehab begins immediately

Arrhythmias (Cardiac Dysrhythmias)

deviations from normal cardiac rate or rhythm

What causes arrhythmias?

-electrolyte abnormalities

-fever

-hypoxia

-stress

-infection

-drug toxicity

Electrocardiography (ECG)

for monitoring the conduction system - Detects abnormalities

3 different arrhythmias

-premature atrial contractions

-atrial flutter

-atrial fibrillation

Premature Atrial Contractions or beats (PACs, PABs)

-extra contraction or ectopic beats

-irritable atrial muscle cells outside conduction pathway

Atrial Flutter

-atrial heart rate of 160 to 350 beats/min

-AV node delays conduction - ventricular rate slower

Atrial fibrillation

-rate over 350 beats/min

-causes pooling of blood in the atria

-thrombus formation is a risk

-not life threatening

-70% of blood still going to the heart

-can lead to a stroke

Heart block

conduction excessively delayed or stopped at AV node or bundle of His

the 3 heart blocks

-first-degree block

-second-degree block

-third-degree block

first-degree block

conduction delay between atrial and ventricular contractions

Second-degree block

every second to third atrial beat dropped at AV node

Third-degree block

No transmission from atria to ventricles

Bundle branch block

interference with conduction in one of the bundle branches

The three ventricular conduction abnormalities

-ventricular tachycardia

-premature ventricular contractions (PVCs)

-Ventricular Fibrillation

Ventricular tachycardia

-lower chambers beats out of sync, usually >100

-likely to reduce cardiac Output as reduced diastole occurs

Premature ventricular contractions (PVCs)

-additional beats from ventricular muscle cell or ectopic pacemaker

-may lead to ventricular fibrillation

What happens to muscle fibers during ventricular fibrillation?

Muscle fibers contract independently and rapidly.

What occurs if ventricular fibrillation is not treated immediately?

Cardiac standstill occurs.

What is the response time for treating ventricular fibrillation?

90 seconds to 2 minutes.

What is the first step in treating cardiac dysrhythmias?

Determination of cause to treat properly

What type of drugs are effective in treating many cardiac dysrhythmias?

Antidysrhythmic drugs

What is required for SA nodal problems or total heart block?

Pacemaker

What device may be implanted for the conversion of ventricular fibrillation?

Defibrillator

Cardiac arrest

-flat ECG

-no conduction of impulses

Reasons for cardiac arrest

-excessive vagal nerve stimulation

-potassium imbalance

-cardiogenic shock

-drug toxicity

-insufficient oxygen

-respiratory arrest

-blow to heart (baseball to the chest)

What is usually a complication of Congestive Heart Failure (CHF)?

Another cardiopulmonary condition.

What may contribute to Congestive Heart Failure (CHF)?

A combination of factors.

What do various compensation mechanisms do in Congestive Heart Failure (CHF)?

They maintain cardiac output, but some often aggravate the condition.

What decreases in CHF?

cardiac output or stroke volume

Backup and congestion develop as coronary demands for oxygen and glucose are not met. True or false?

True

oliguria

low urine output

s/s CHF

-decreased blood supply to tissue

-fatigue and weakness

-Dyspnea and SOB

-oliguria

-tachycardia

-cutaneous and visceral vasoconstriction

left-sided failure of CHF

-pulmonary congestion

-dyspnea and orthopnea

-hemoptysis

-paroxysmal nocturnal dyspnea

paroxysmal nocturnal dyspnea

-acute pulmonary edema

-usually develops during sleep

-excess fluid in lungs frequently leads to infections such as pneumonia

What kills left-side CHF?

pneumonia typically

Right-sided CHF

-systemic

-pitting edema in feet, legs, or buttocks

-increased pressure in jugular veins leads to distention

-hepatomegaly

-splenomegaly

-ascites (abdominal distention)

Acute right-sided CHF

-flushed face

-distended neck veins

-headache

-visual disturbance

Young children with CHF

-often secondary to congenital heart disease

-feeding difficulties often first sign

-short sleep periods

-tripod position to play

-cough

-rapid grunting respirations

-flared nostril

-wheezing

-radiographs show cardiomegaly

-arterial blood gases used to measure hypoxia

Cardiac anomalies

structural defects in the heart that develop during the first 8 weeks of embryonic life

2 congenital heart disease

-valvular defects

-septal defects

Valvular defects

valves

Septal defects

walls

How to detect congenital heart defects?

detected by the presence of heart murmur

What may happen to child if untreated congenital heart defect?

child may develop heart failure

What makes a baby cyanotic or acyanotic?

depends on direction of shunting

s/s congenital heart defects

-pallor

-dyspnea

-tachycardia

-clubbed fingers

-squatting position for toddlers and older children (for blood flow and comfort)

-intolerance of exercise and exposure to cold weather

dx test for congenital heart disease

-severe defects are often diagnosed at birth

-some may not be detected for some time

-radiography

-diagnostic imaging

-cardiac cath

-echo

-ECG

-surgical repair

Ventricular Septal Defect (VSD)

-most common congenital heart defect

-opening in the interventricular septum

Untreated VSD

-pressure usually higher in left ventricle

-shunt from left to right

-Acyanotic condition unless respiratory condition increases pressure in right ventricle

What are the two types of valvular defects?

Stenosis and valvular incompetence

What happens in valvular incompetence?

The valve fails to close completely, causing blood to regurgitate or leak backward.

What is mitral valve prolapse?

A condition where the mitral valve has abnormally enlarged and floppy leaflets.

What are the two types of surgical replacement for valves?

Mechanical or animal tissue valves.

Which valves are commonly affected by valvular defects?

Aortic and pulmonary valves.

Tetralogy of Fallot

-most common cyanotic (R -> L shunt) congenital heart condition

Cyanosis

shunt bypasses the pulmonary circulation

What does tetralogy of fallot alter?

alters pressures in heart and alters blood flow

four abnormalities of Tetralogy of Fallot

-pulmonary stenosis

-VSD

-Dextroposition of the aorta

-right ventricular hypertrophy