Overview of function & structure of the heart

HEART

- Muscular, pumping organ of the body

- Left mediastinum

- Weigh 300 – 400 grams

- Resembles a closed fist

- Covered by serous membrane – pericardium

Pericardium

Parietal layer Pericardial Visceral layer

Fluid – prevent

Friction rub

Layer

1. Epicardium – outermost
2. Myocardium – inner – responsible for pumping action/ most dangerous layer - cardiogenic shock
3. Endocardium – innermost layer

Chambers

1. Upper – collecting/ receiving chamber - Atria
2. Lower – pumping/ contracting chamber - Ventricles

Valves

1. Atrioventricular valves - Tricuspid & mitral valve

Closure of AV valves – gives rise to 1^st heart sound or S1 or “lub”

2. Semi lunar valve

a.) Pulmonic

b.) Aortic

Closure of semilunar valve – gives rise to 2^nd heart sound or S2 or “dub”

Extra heart Sound

S3 – ventricular Gallop – CHF

S4 – atrial gallop – MI, HPN

Heart conduction system

1. Sino atrial node (SA node) (or Keith-Flock node)

Loc – junction of SVC & Rt atrium

Fx- primary pace maker of heart

-Initiates electric impulse of 60 – 100 bpm

2. Atrioventicular node (AV node or Tawara node)

Loc – inter atrial septum

Delay of electric impulse to allow ventricular filling

3. Bundle of His – location interventricular septum

Rt main Bundle Branch

Lt main Bundle Branch

4. Purkenjie Fiber

Loc- walls of ventricles-- Ventricular contractions

SA node

Purkenjie Fibers

Bundle of His

Complete heart block – insertion of pacemaker at Bundle Branch

Metal – Pace Maker – change q3 – 5 yo

Prolonged PR – atrial fib T wave inversion – MI

ST segment depression – angina widening QRS – arrhythmia

ST – elev – MI

CAD – coronary artery dse or Ischemic Heart Dse (IHD)

Atherosclerosis – Myocrdial injury

Angina Pectoris – Myocardial ischemia

MI- myocardial necrosis

ATHEROSCLEROSIS	ARTEROSCLEROSIS
- Hardening or artery due to fat/ lipid deposits at tunica intima.	- Narrowing or artery due to calcium & CHON deposits at tunica media.

Artery – tunica adventitia – outer

- Tunica intima – innermost

- Tunica media – middle

ATHEROSCLEROSIS

Predisposing Factor

1. Sex – male
2. Black race
3. Hyperlipidemia
4. Smoking
5. HPN
6. DM
7. Oral contraceptive- prolonged use
8. Sedentary lifestyle
9. Obesity
10. Hypothyroidism

Signs & Symptoms

1. Chest pain
2. Dyspnea
3. Tachycardia
4. Palpitations
5. Diaphoresis

Treatment

P – percutaneous

T – tansluminar

C – coronary

A – angioplasty

Obj:

1. To revascularize the myocardium
2. To prevent angina

3. Increase survival rate

PTCA – done to pt with single occluded vessel .

Multiple occluded vessels

C – coronary

A – arterial

B – bypass

A –and

G – graft surgery

Nsg Mgt Before CABAG

1. Deep breathing cough exercises
2. Use of incentive spirometer
3. Leg exercises

Congenital anomalies:

1. CHD (Congenital heart disease)

§ 2 types: acyanotic and cyanotic

§ Risk factors:

o Maternal infection

o Advancing age

o Medical condition

o Alcoholism

§ Acyanotic: with oxygenation

o Shunting of blood from left side to right side of the heart

o Symptoms: no cyanosis

o Complications: CHF

o Position: semi fowlers

§ Cyanotic: unoxygenated

o Shunting of blood from right to left side of the heart

o Symptoms: with cyanosis/bluish discoloration

o Complication: prone to CVA due to polycythemia, thrombosis

o Position: squatting

§ Common s/sx with acyanotic and cyanotic chd:

o Brow sweating

o Difficulty in feeding

o Frequent urti

o Stunted growth

o Tachypnea

o Tachycardia

§ Nrsg dx: altered tissue perfusion

§ Goal: oxygen, warmth (during operation)

Types of Acyanotic CHD

- Conditions with increased pulmonary blood flow

1. VSD (ventricular septal defect)

- Most common of all congenital defect

- Problem: opening is present in the septum between the two ventricles due to pressure on the left ventricle than that of the right, the blood shunt from left to right across the septum

2. ASD (Atrial septal defect)

- Abnormal communication between the 2 atria

- Frequent in girls than boys

3. PDA (Patent ductus arteriosus)

- Common in girls

- Ductus arteriosus is an accessory fetal structures that connects pulmonary artery to the aorta

- Problem: if failed to close after birth: blood will shunt from the aorta to the pulmonary artery to left atrium to left ventricle then to the aorta to the pulmonary artery again

- Sx: machinery murmur

- Lad data: 2d echo

- Mgt: indomethacin – a prostaglandin inhibitor

· Decrease prostaglandin will stimulate the closure of ductus arteriosus

- Admin oxygen

- Conditions with obstructive congenital heart disease

1. Pulmonic stenosis

- Problem: narrowing of the pulmonic valve or pulmo artery

- Right ventricle cant evacuate the blood which may lead to right ventricular hypertrophy

2. Aortic stenosis

- Stricture of the aortic valve which prevents blood from passing freely from the left ventricle of the heart into the aorta thus increasing pressure in the heart and lead to left ventricle hypertrophy

3. Coarctation of aorta

- Narrowing of the lumen of the aorta due to constricting band

- Sx: higher BP in upper extremities