Anatomy of the Cardiovascular System

Cardiovascular System

• The cardiovascular system consists of the heart, vessels, and blood.

Heart

• The heart is cone-shaped, weighing approximately 320 grams in males and 270 grams in females.
• It has three surfaces: anterior (sternocostal), inferior (diaphragmatic), and left (pulmonary).
• The heart is located in the middle mediastinum, with one-third on the right side and two-thirds on the left side of the midline.
• The apex of the heart is below and to the left, related to the 5th left intercostal space, 8 cm from the midline.

Position of the Heart

• The base of the heart is located in the superior and posterior regions.
• The apex is inferior and anterior.

Chambers of the Heart

• The heart has four chambers: two atria and two ventricles.
• The right ventricle forms most of the anterior surface.

Grooves on the Heart

• There are two grooves on the anterior surface: the coronary sulcus (or atrioventricular sulcus) and the anterior interventricular sulcus.
• There are two grooves on the inferior surface: the coronary sulcus (or atrioventricular sulcus) and the inferior interventricular sulcus.

Surface Marking of the Heart

• The right border of the heart extends from the 3rd right costal cartilage to the 6th costal cartilage, 1 cm to the right of the sternal border.
• The left border extends from the 2nd left costal cartilage to the 5th left intercostal space, 8 cm from the midline.

Valves of the Heart

• There are four valves: tricuspid valve, mitral valve, pulmonary valve, and aortic valve.

Right Atrium

• The posterior smooth part is the sinus venarum.
• The anterior part has pectinate muscles.
• There is a crista terminalis on the lateral wall.
• The fossa ovalis is on the medial wall.
• The valve of inferior vena cava (Ostashian valve) and the valve of coronary sinus (Thebesian valve) are present.

Left Atrium

• The wall is smooth, except in the left auricle.
• There are four openings of pulmonary veins.
• The mitral valve is between the left atrium and left ventricle.

Ventricular Muscles

• There are three types of ventricular muscles: ridge, bridge, and papillary.

Layers of the Heart

• There are three layers: epicardium (outer layer), myocardium (thick middle layer), and endocardium (inner layer).

Coronary Arteries

• The coronary arteries originate from the aorta and supply the heart with blood flow.
• The main coronary artery lies on the surface of the heart (epicardial coronary arteries).
• Small penetrating arteries supply the myocardial muscle.

Cardiac Conduction System

• The cardiac conduction system controls the heart rate.
• The sinoatrial node (SA node) initiates impulses (70-80 times per minute) and is located in the back wall of the right atrium near the entrance of the vena cava superior.
• The atrioventricular node (AV node) is located in the bottom of the right atrium near the septum and conducts impulses more slowly, causing a delay.

Pericardium

• The pericardium is a double-walled sac around the heart.
• It is composed of the fibrous pericardium and the serous pericardium.
• The pericardium protects and anchors the heart, prevents overfilling, and allows for a friction-free environment.

Clinical Findings

• Patient presentation: shortness of breath, fatigue, and racing heart during exercise.
• Physical examination: pulse rate of 122 bpm, auscultation reveals a mid-diastolic murmur and systolic "snap" over the heart apex, and crackles detected in all lung lobes.
• Echocardiography reveals calcification in both leaflets of the mitral valve, doming of the anterior leaflet, and thickened and shortened chordae tendineae.

Main Contributing Risk Factors to Cardiac Problems

• Hypertension
• Hyperlipidemia
• Smoking
• Diabetes

These are considered modifiable risk factors.