NEET MDS Synopsis
Cardiac arrhythmia
General Pathology
Cardiac arrhythmia
Cardiac arrhythmia is a group of conditions in which muscle contraction of the heart is irregular for any reason.
Tachycardia :A rhythm of the heart at a rate of more than 100 beats/minute , palpitation present
Causes : stress, caffeine, alcohol, hyperthyroidism or drugs
Bradycardia : slow rhythm of the heart at a rate less than 60 beats/min
Atrial Arrhythmias
- Atrial fibrillation
Atrial Dysrhythmias
- Premature atrial contraction
- Atrial flutter
- Supraventricular tachycardia
- Sick sinus syndrome
Ventricular Arrhythmias
- Ventricular fibrillation
Ventricular Dysrhythmias
- Premature ventricular contraction
- Pulseless electrical activity
- Ventricular tachycardia
- Asystole
Heart Blocks
- First degree heart block
- Second degree heart block
o Type 1 Second degree heart block a.k.a. Mobitz I or Wenckebach
o Type 2 Second degree heart block a.k.a. Mobitz II
- Third degree heart block a.k.a. complete heart block
Atrial fibrillation
Atrial fibrillation is a cardiac arrhythmia (an abnormality of heart rate or rhythm) originating in the atria.
AF is the most common cardiac arrhythmia
Signs and symptoms
Rapid and irregular heart rates
palpitations, exercise intolerance, and occasionally produce angina and congestive symptoms of shortness of breath or edema
Paroxysmal atrial fibrillation is the episodic occurence of the arrhythmia Episodes may occur with sleep or with exercise
Diagnosis:
Electrocardiogram
- absence of P waves
- unorganized electrical activity in their place
- irregularity of R-R interval due to irregular conduction of impulses to the ventricles
Causes:
- Arterial hypertension
- Mitral valve disease (e.g. due to rheumatic heart disease or mitral valve prolapse)
- Heart surgery
- Coronary heart disease
- Excessive alcohol consumption ("binge drinking" or "holiday heart")
- Hyperthyroidism
- Hyperstimulation of the vagus nerve, usually by having large meals
Treatment
Rate control by
Beta blockers (e.g. metoprolol)
Digoxin
Calcium channel blockers (e.g. verapamil)
Rhythm control
Electrical cardioverion by application of a DC electrical shock
Chemical cardioversion is performed with drugs eg amiodarone
Radiofrequency ablation : uses radiofrequency energy to destroy abnormal electrical pathways in heart tissue It is used in recurrent AF
In confirmed AF, anticoagulant treatment is a crucial way to prevent stroke
Atrial flutter
Atrial flutter is a regular, rhythmic tachycardia originating in the atria. The rate in the atria is over 220 beats/minute, and typically about 300 beats/minute
he morphology on the surface EKG is typically a sawtooth pattern.
The ventricles do not beat as fast as the atria in atrial flutter
Supraventricular tachycardia
apid rhythm of the heart in which the origin of the electrical signal is either the atria or the AV node
it is important to determine whether a wide-complex tachycardia is an SVT or a ventricular tachycardia, since they are treated differently
Sick sinus syndrome : a group of abnormal heartbeats (arrhythmias) presumably caused by a malfunction of the sinus node, the heart's "natural" pacemaker.
Ventricular fibrillation
is a cardiac condition which consists of a lack of coordination of the contraction of the muscle tissue of the large chambers of the heart. The ventricular muscle twitches randomly, rather than contracting in unison, and so the ventricles fail to pump blood into the arteries and into systemic circulation.
Ventricular fibrillation is a medical emergency: if the arrhythmia continues for more than a few seconds, blood circulation will cease, as evidenced by lack of pulse, blood pressure and respiration, and death will occur. Ventricular fibrillation is a cause of cardiac arrest and sudden cardiac death
Classification of Dental Fractures
Pedodontics
IMMUNO PATHOLOGY
General Pathology
IMMUNO PATHOLOGY
Abnormalities of immune reactions are of 3 main groups
- Hypersensitivity,
- Immuno deficiency,
- Auto immunity.
Hypersensitivity (ALLERGY)
This is an exaggerated or altered immune response resulting in adverse effects
They are classified into 4 main types.
I. Type I-(reaginic, anaphylactic). This is mediated by cytophylic Ig E antibodies, which get bound to mast cells. On re-exposure, the Ag-Ab reaction occurs on the mast cell surface releasing histamine.
Clinical situations
I. Systemic anaphylaxis, presenting with bronchospasm oedema hypertension, and even death.
2. Local (atopic) allergy.
- Allergic rhinitis (hay fever)
- Asthma
- Urticaria.
- Food allergies.
2. Type II. (cytotoxic). Antibody combines with antigen present on-cell surface. The antigen may be naturally present on the surface or an extrinsic substance (e.g.drug) attached to cell surface.
The cell is then destroyed by complement mediated lysis (C89) or phagocytosis of the antibody coated cell.
Clinical situations
- Haemolytic anemia.
- Transfusion reaction
- Auto immune haemolytic anemia.
- Haemolysis due to some drugs like Alpha methyl dopa
2. Drug induced thrombocytopenia (especially sedormid).
3 Agranulocytosis due to sensitivity to some drugs.
4 Goodpasture’s syndrome-glomermerulonephritis due to anti basement membrane antibodies.
3. Type III. (Immune complex disease). Circulating immune complexes especially small soluble complexes tend to deposit in tissues especially kidney, joints, heart and arteries.
These then cause clumping of platelets with subsequent release of histamine. and serotonin resulting in increased permeability. Also, complement activation occurs which being chemotactic results in aggregation of polymorphs and necrotising vasculitis due to release of lysosmal enzymes
Clinical situations
- Serum sickness.
- Immune complex glomerulonephritis.
- Systemic lupus erythematosus.
- Allergic alveolitis.
- Immune based vasculitis like
o Drug induced vasculitis.
o Henoch – Schonlein purpura
4. Type IV. (Cell mediated). The sensitized lymphocytes may cause damage by cytotoxicity or by lymphokines and secondarily involving macrophages in the reaction.
Clinical situations
I. Caseation necrosis in tuberculosis.
2. Contact dermatitis to
- Metals.
- Rubber.
- Drugs (topical).
- Dinitrochlorbenzene (DNCB).
5. Type V. (stimulatory) This is classed by some workers separately and by other with cytotoxic type (Type II) with a stimulatory instead of toxic effect
Clinical Situations :
LATS (long acting thyroid stimulator) results in thyrotoxicosis (Grave’s disease)
Verruca vulgaris
General Pathology
Verruca vulgaris
1. Commonly known as warts.
2. Caused by the human papillomavirus (HPV).
3. Warts can be seen on skin or as an oral lesion (vermilion border, oral mucosa, or tongue).
4. Transmitted by contact or autoinoculation.
5. A benign lesion.
Impression Making Techniques
Prosthodontics
Impression making is a critical step in prosthodontics and orthodontics, as
it captures the details of the oral cavity for the fabrication of dental
prostheses. There are several techniques for making impressions, each with its
own principles and applications. Here, we will discuss three primary
impression-making techniques: Mucostatic, Mucocompressive, and Selective
Pressure Impression Techniques.
1. Mucostatic or Passive Impression Technique
Proposed by: Richardson and Henry Page
Materials Used: Plaster of Paris and Alginate
Key Features:
Relaxed Condition: Records the oral mucous membrane
and jaws in a normal, relaxed condition.
Tray Design: Utilizes an oversized tray to
accommodate the relaxed tissues.
Tissue Contact: Achieves intimate contact of the
tissues with the denture base, which enhances stability.
Peripheral Seal: This technique has a poor
peripheral seal, which can affect retention.
Outcome: The resulting denture will have good
stability but poor retention due to the lack of a proper seal.
2. Mucocompressive Impression Technique
Proposed by: Carole Jones
Materials Used: Impression compound and Zinc Oxide
Eugenol (ZoE)
Key Features:
Functional Recording: Records the oral tissues in a
functional and displaced form, capturing the active state of the
tissues.
Retention: Provides good retention due to the
compression of the tissues during the impression process.
Displacement Issues: Dentures made using this
technique may tend to get displaced due to tissue rebound when the
tissues return to their resting state after the impression is taken.
3. Selective Pressure Impression Technique
Proposed by: Boucher
Materials Used: Special tray with Zinc Oxide Eugenol (ZoE)
wash impression
Key Features:
Stress Distribution: Loads acting on the denture
are transmitted to the stress-bearing areas of the oral tissues.
Tray Design: A special tray is designed such that
the tissues contacted by the tray are recorded under pressure, while the
tissues not contacted by the tray are recorded in a state of rest.
Balanced Recording: This technique allows for a
more balanced impression, capturing both the functional and relaxed
states of the oral tissues.
Lymphomas
General Pathology
Lymphomas
A. Hodgkin’s disease
1. Characterized by enlarged lymph nodes and the presence of Reed-Sternberg cells (multinucleated giant cells) in lymphoid tissues.
2. Disease spreads from lymph node to lymph node in a contiguous manner.
3. Enlarged cervical lymph nodes are most commonly the first lymphadenopathy observed.
4. The cause is unknown.
5. Occurs before age 30.
6. Prognosis of disease depends largely on the extent of lymph node spread and systemic involvement.
B. Non-Hodgkin’s lymphoma
1. Characterized by tumor formation in the lymph nodes.
2. Tumors do not spread in a contiguous manner.
3. Most often caused by the proliferation of abnormal B cells.
4. Occurs after age 40.
5. Example: Burkitt’s lymphoma
a. Commonly associated with an EpsteinBarr virus (EBV) infection and a genetic mutation resulting from the translocation of the C-myc gene from chromosome 8 to 14.
b. The African type occurs in African children and commonly affects the mandible or maxilla.
c. In the United States, it most commonly affects the abdomen.
d. Histologically, the tumor displays a characteristic “starry-sky” appearance.
Monoamine oxidase inhibitors
Pharmacology
Monoamine oxidase inhibitors (MAOIs)
e.g. phenelzine, tranylcypromine, moclobemide
- Belong to first generation antidepressants with TCAs
- Most MAOIs irreversibly inhibit the intraneuronal catabolism of norepinephrine and serotonin by MAO-A and MAO-B
- increase brain levels of noradrenaline and 5-HT
- Moclobemide causes selective, reversible inhibition of MAO-A
DRUG INTERACTIONS
Hypertensive crises similar to cheese reaction with OTC cough/cold preparations containing indirect-sympathomimetics
e.g. ephedrine
- Other antidepressants should not be started at least 2 weeks after stopping MAOIs and vice versa due to risk of serotonin syndrome
- Similar interaction with pethidine
ADVERSE DRUG REACTIONS
- Antimuscarinic side effects (e.g. dry mouth, blurred vision, urinary retention)vision, urinary retention)
- Excessive central stimulation causes tremors, excitement and insomnia
- Postural hypotension
- Increased appetite with weight gain
Empyema
Medicine
• Thoracic empyema is purulent pleural effusion
• End stage of pleural effusion if not treated properly
• Thick pus with a thick cortex of fibrin and coagulum over lung
Etiology
Most common cause : Parapneumonic, Postsurgical & post-traumatic
Most common: pneumonia → extension of bacterial infection into the pleural space
Less common: infected hemothorax, ruptured lung abscess, esophageal tear, thoracic trauma
Empyema due to pneumonia three phase
The exudative phase :
- protein > 3g/100 ml
- Infection from lung
- Antibiotics & aspiration or drainage
The fibrinopurulent phase :(next few days)
Pleural fluid become thick ,
Drainage must
The organized phase:
- Lung trapped by thick peel or cortex
- Surgical management
- VATS,
- thorocotomy
Condition predispose to Empyema
Pulmonary infection:
- Unresolved pneumonia
- Broncietasis
- Tuberculosis
- Fungal infection
- Lung abscess
Aspiration of pleural effusion
Trauma :
- Penetrating injury
- Surgery
- Oesophgeal peforation
Extrapulmonary sources : Subphernic abscess
Bone infection osteomyelitits ribs and vertebra