Heart Structure and Blood Flow

Heart Structure

• The pericardium secures the heart in the chest, protects against infection, and has receptors for regulating blood pressure and heart rate.
• The two layers of the pericardium are the epicardium (inner visceral layer) and the parietal layer (outer layer).
• Pericardial fluid between these layers cushions and reduces friction.
• The myocardium, a thick, muscular middle layer, is most pronounced in the left ventricle due to its role in pumping blood to the body.
• The myocardium can undergo hypertrophy if workload increases (hypertension over time).
• The Endocardium is the inner lining, forming a continuous endothelial layer connecting arteries and veins, ensuring a closed circulatory system.

Valves and Blood Flow

• The heart includes the right atrium, left atrium, right ventricle, and left ventricle.
• The heart includes chambers separated by the interventricular septum.
• Valves separate the atria from the ventricle .
• Valves regulate blood flow from the ventricles into the pulmonary artery and aorta.

Coronary Arterial Circulation

• The heart has several major arteries, including the left coronary artery, circumflex artery, left (obtuse) marginal artery, right coronary artery, right (acute) marginal artery, left anterior descending artery, and diagonal arteries.

The Cardiac Cycle

• Atrial contraction forces blood into the ventricles during the Atriole systole phase.
• Ventricular contraction pushes AV valves closed during the first Ventricular systole phase.
• Semilunar valves open, and blood is ejected during the second Ventricular systole phase.
• Semilunar valves close, blood flows into atria during the early Ventricular diastole phase.
• The chamber relaxes and fills ventricles passively during the late Ventricular diastole phase.
• The P-wave represents atria depolarization, and the QRS Complex represents ventricles depolarization.
• The T-Wave represents ventricles repolarization.

Conduction System

• Cardiac contractions rely on ion movement and electrical impulses between myocardial cells.
• Impulses in the heart create a weak electrical current or action potentials.
• Electrical currents move Na+, Ca+, and K+ ions through cell membrane channels.
• Two types of action potentials that regulate the cardiac cycle are slow and fast responses.

Cardiac Conduction

• Depolarization = Squeeze and push out
• Repolarization = Relax and fill
• P wave: Atria's depolarization from the sinoatrial node PQ interval: Depolarization of the AV node and bundle fibers
• QRS complex: Ventricles' depolarization
• U wave: Purkinje fibers' repolarization

Cardiac Output

• Cardiac output is measured by heart rate multiplied by stroke volume and is influenced by various factors like afterload, preload, and contractility. Afterload: Resistance the heart must overcome to eject blood. It is based on systemic vascular resistance (BP), and conditions like atherosclerosis and aortic stenosis increase afterload
• Preload: Stretch of the myocardium affects blood volume returning to the heart.
• Contractility: Ability and force of myocardium contraction.

Blood Pressure Control

• Baroreceptors sense pressure in the heart and aortic arch, signaling the brainstem to activate the ANS for ventilation and perfusion.
• Chemoreceptors sense pH, O2, and CO2 changes, alerting the ANS to adjust ventilation and perfusion.
• RAAS hormones regulate vasoconstriction and fluid retention.
• ADH maintains fluid balance and can act as a potent vasoconstrictor

Altered Perfusion

• Ventilation-Perfusion Mismatch, Impaired Circulation, Inadequate Cardiac Output, and Excessive Perfusion Demands can be the cause of Altered Perfusion

Impaired Circulation

• Impaired circulation is inadequate blood flow to tissues and organs such as Hemorrhage, Thrombus/Embolus Atherosclerosis, Arterial Aneurysms, Venous Stasis, and Heart Defects.

Hemorrhage

• Hemorrhage is a loss of blood through the vessel wall.
• The most common cause of loss of blood is vascular injury as a result of Trauma
• Aneurysms, coagulation disorders (hemophilia, thrombocytopenia), and neoplasms can also cause trauma.

Thrombus/Embolus

• Stationary blood clot in blood vessel or heart Thrombus
• Detached thrombus that can lodge in smaller vessels and block blood flow Embolus
• The causes of thrombus formation is caused by trauma, surgery, hypertension, atherosclerosis, and smoking
• Abnormal blood flow, slow or stagnant circulation (immobility, atrial fibrillation (Afib), venous stasis) turbulent blood flow in the heart (Afib or valvular disorders) can all cause improper thrombus formation.
• Excessive blood clotting caused by oral contraceptives, sickle cell disease, and dehydration, is also a main reason for thrombus formation

Deep Vein Thrombosis (DVT)

• Thrombi forms in venous circulation of the lower extremities
• The virchow triad is the common cause
• Risk factor- Vein damage with poor circulation and Embolism travel to the lungs impairing gas exchange.

Atherosclerosis

• Irregularly distributed lipid deposits in large and mediums arteries inner layer.
• Caused by injury to intima caused by smoking and hypertension.
• Low-density lipoproteins (LDL) becomes trapped as the arteries become narrow with fatty proteins.
• Occlusion of plaque occurs where plaque rupture or thrombosis froms.

Arterial Aneurysm

• Arterial aneurysms - bulges in an artery are caused by chronically high blood pressure and/or weakness in vessel wall - associated with nicotine from smoking
• Measured in mm or cm and aneurysms considered significant with larger then 3.0 men; 2.5 cm in women
• Normal may be present with a pulsatile mass on palpitation of thorax with thin abdominal wall

Heart Defects

• Shunting - Heart defect where blood movement across the chamber
• Regurgitation defect when blood flow allows in backward flow - can be caused by stenois
• Heart Structure does not resist blood flow

Inadequate Cardiac Output

• Impaired pumping to the pulmonary or systemic circulation that results in the inability to meet the metabolic needs for dehydration, hemorrhage, or anemia.
• Ventricular heart defects of electrical conduction - damage as the heart fails its conduction of rhythm
• Reduced oxygen to brain that presents the Loc like weakness with chest pain due to a electrical issue

Hypertension

• Hypertension (HTN) is a progressive cardiovascular syndrome that includes elevated blood pressure. Systolic is greater then 130, and diastolic is greater than 80.

• Primary hypertension is unknown while secondary causes by other conditions like kidney problems.

• Elevated Systolic as only Elevated Systolic hypertension causes by family History, age, stress, high-cholesterol-diet, excessive alcohol, and smoking that increase cardiac output that causes structural or functional change from the lack of sodium.

• CNS Effect- High B.P reduces brain function and high oxygen.

• Cardio Effect- Arterial obstruction due to hyperoxemia.

• Chronic kidney damage or inflammation happens in the kidneys.

• Is often asymptotic and is detected during B.P screenings.

Shock

• The condition of circulatory failure and impaired perfusion that effect vital organs.
• Often equates to hypotension indicate of an ineffective balance. Types of shock
• Cardio: Low output
• Hypotension: Reduced blood volume
• Septic Shock: Systemic inflammation
• Neurogenic: sympathetic control loose leading to low perfusion.
• Ana-phylatic: Immune resonce. Compensatory Mechanisms - increasing rate and contraction with blood re-absorbed
• Goals- Blood shunting and promote cardio output
• Downward Spiral: anaerobic, cellular metabolism fails leading to death.

Coronary Artery Disease (CAD)

• Narrow/obstructions of Coronary and reduced blood flow called plaque in arterial wall
• Occurs during plaque erosion
• Patient can be asymptomatic and has chest pain and shortness of breath
• Check ST segment elevation
• Check for Cardiac biomarkers levels, and have regular montior lipid levels.

Acute Coronary Syndrome (ACS)

• Includes unstable angina, non-ST-segment elevation myocardial infarction (NSTEMI), and ST-segment elevation myocardial infarction (STEMI).
• Caused by atherosclerosis and causes with angina, GI issues
• Essential assessment monitoring.

Acute Coronary Intervention

• Check percutaneous levels along with Coronary artery bypass.

Myocardial Pain Location

• Check cardiac output (CO) and identify pain locations

Cardiac Disease and Recovery

• Scarred heart tissue from replace necrotice cells within weeks

Cardiac Arrhythmia and Infraction

• Caused by a ST elevation and non elevation due to the myocardium failing
• A non ST elevation shows ST depressio, with T waves - QRS
• Elevation segment shows abnormal QRS

Angina Pectoris

• Angina is caused by Ischemia and chest pains.
• Types of angina

1. Stable
2. Variant or Vasospastic/Prinzmetal)
3. Unstable

• Has shortness of breath with nausea.

Cardiomyopathies

• affect Cardiac function
• Occurs with DCM- L ventricle won't stretch with normal heart.
• HCM- L vent too big with low heart
• RCM or ARVC
• SOB- with Palpitations and chest Pains- synoscope

Heart Failure

• Complex system with poor cardio that can't meets output demand.
• Caused by- valvular, long term- HTN.
• Systolic or dystonic depending to the cardio and tissue perfusion

Heart Failure Factors

• High weight. edema, SOB, paroxymal etc
• Mont- changes in weight, B,P, eletrolights
• Increase BNP

Heart Failure Rate

• Preserve all for fillinf.
• Dystoic with conctractio
• Distencsion overload. greater then range.
• High JVD range.

Pericardititis

• The inflammation of the pericardium which is sac surrounding the heart that is caused by infections.
• Causes chest pain that is sharp.
• ECG level increased.

Infective Endocarditis

Infection - is caused by staph infection.

• Due to valves that lack proper infection with embolization.
• Caused by new heart damage - may be persistent. .

Rheumatic Heart Disease

• The heart can not treat streptococcal infections
• Inflammable damages is a complication for valves causing scarring.
• Check for elevated infections.

The valuvlar Heart Disease

• Dysunction causes a dysfunction of a or more arties-
• Reduces heart function due to abnormalities. caused by ischmia-

The Cardiovascular system

• Occurs when the heart has abnormal blood flow.
• Can be detected with blood in the heart that causes issues in heart.

Cardio Tamponade

• A medical emergency. Where fluid is increased around the heart.
• Due to reduced cardio.
• Causes: Trauma, Pericarditis - may be potential life threating
• Check for distention or exaggeration.

Stroke

• An acute illness with inflammation that affects the brain.
• Major-Diabetes /Smoke.
• Types are: Emoblic
• Hemorrhagic

Heart Conduction System

• Electro activity happens to the S.A
• Can be electrical from bundle for the heart

Heart rhythm

• Need to check sinus bradycardia and the output with less the 60 beats a min.
• Check for abnormal heart rythem.

Atrial Fiber/Flutter

• flutter irregular or a- fib
• Uncontrolled- greater then 90bpm
• Controlled – less than 90bpm
• Check P's

Atrioventricular

• 1st degree is Regular vs 3rd degree is always Bradycardic

Premature Contraction

Pac'S come from electrical of of the sequence.

Vent Tach

• QRS only. check artifact or for the patients.

Ventricular Fibrilation

• There is a code blue- need to cpr and d-fib

Too Short