The (AVN) Atrial Ventricular Node is a group of specialized cells located in the lower part of the right atrium above the tricuspid valve base. Its function is to Delay, Relay and Filter impulses as they pass through the Ventricles. The nodal cells have pacemaker properties and can pace the heart at a rate of 40-60b/min. Rhythms coming from the AV junction are called .Junctional dysrhythmias. The electrical impulse must travel backward ( Retrograde) to activate the atria.

A normal heartbeat results from an electrical impulse that originates from the hearts primary pace maker-(SA node) • The Normal sinus rhythm records the hearts electrical impulse that starts in the SAN spreading through the normal conduction pathway. • The SAN dominates other areas that may pace the heart slower and abnormally. All other rhythms will be compared to the Normal Sinus Rhythm

The ventricles (purkinje fibres) may assume the function of pacing the heart, they pace at a slower rate 20-40b/min which cannot sustain the body's perfusion requirements. Rhythms originating from the ventricles are called ventricular arrhythmias because they originate in the ventricles. Ventricular arrhythmias occur when:- a) The SAN fails to initiate an impulse b) The AVN does not pick to pace c) There is an irritable foci in the ventricular muscle

Sickle cell disease (SCD) • A group of hereditary disorders in which the normal adult hemoglobin (hemoglobin A) is partly or completely replaced by abnormal sickle hemoglobin (HgbS). • The most common genetic hematologic condition in children • Transmitted by autosomal recessive pattern of inheritance. • Patient with this condition is homozygous for the sickle cell gene, i.e. both genes are abnormal. • The basic defect responsible for the sickling of erythrocytes is contained in the globin fraction of hemoglobin • The mode of transmission is hereditary • The gene that determines the production of HgbS is situated on an autosome.

These are therapies aimed at preventing, alleviating the underlying cause or treating the hematological disorder • They include 1. Nutritional therapy: meal management to ensure rich sources of iron, vitamin K, vitamin B9. 2. Supplements: administration of folate, iron sulfate. 3. Treatment of underlying cause: antimalarial, deworming, ulcer treatment

Outline 1. Review the role of valves in cardiac cycle 2. Define valvular heart disease 3. Identify types of VHD 4. Explain the assessment and diagnostic tests 5. Describe the management of patient with VHD

History taking 1. Nutrition: feeding habits; typical meal – to determine deficiencies 2. use of prescription and over-the-counter medications: most hematological conditions can result from herbs, or certain medications. 3. Prior chemotherapy or radiotherapy

It is a condition of combine platelet and coagulation factor disorder. • It is characterized by widespread coagulation and bleeding in the vascular compartment. • DIC occurs secondary to inappropriate systemic activation of normal clotting mechanisms. • It is associated with underlying disease manifested as uncontrolled activation of coagulation and fibrinolysis.

3 elements ensures adequate tissue perfusion 1. Functioning pump (myocardial contractility) 2. Rate of Myocardial contraction 3. Adequate volume of blood (preload) 4. Normal vascular tone, SVR (Afterload) • In order for adequate tissue perfusion to occur, cardiac output must be sufficient to deliver nutrient- and oxygen rich blood to the tissues.

Disorders of hemostasis – hypercoagulability states Disorders occurring due to imbalance between procoagulants and anticoagulants. Pro-coagulant factors: Platelets clotting factors Ca2 PLUS molecules released by damaged tissues Anticoagulant factors Protein C Plasmin Antithrombin III