THROMBOSIS

THROMBOSIS

Thrombosis is the formation of a blood clot (thrombus) inside a blood vessel, obstructing the flow of blood through the circulatory system. When a blood vessel is injured, the body uses platelets and fibrin to form a blood clot, because the first step in repairing it (hemostasis) is to prevent loss of blood. If that mechanism causes too much clotting and the clot breaks free, an embolus is formed. Thromboembolism is both thrombosis and its main complication, which is embolization.

Causes;

1. Hypercoagulability 2. Endothelial cell injury

2. Disturbed blood flow

Classification:

There are two distinct forms of thrombosis, each of which can be presented by several subtypes.

Venous thrombosis:

Venous thrombosis is the formation of a thrombus (blood clot) within a vein. There are several diseases which can be classified under this category:

Deep vein thrombosis;

Deep vein thrombosis (DVT) is the formation of a blood clot within a deep vein. It most commonly affects leg veins, such as the femoral vein. Three factors are important in the formation of a blood clot within a deep vein—these are the rate of blood flow, the thickness of the blood and qualities of the vessel wall. Classical signs of DVT include swelling, pain and redness of the affected area.

Portal vein thrombosis

Portal vein thrombosis is a form of venous thrombosis affecting the hepatic portal vein, which can lead to portal hypertension and reduction of the blood supply to the liver.

Renal vein thrombosis:

Renal vein thrombosis is the obstruction of the renal vein by a thrombus. This tends to lead to reduced drainage from the kidney.

Jugular Vein Thrombosis:

Jugular Vein Thrombosis is a condition that may occur due to infection, intravenous drug use or malignancy.

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APPENDICITIS

APPENDICITIS

Appendicitis is a condition characterized by inflammation of the appendix. It is classified as a medical emergency and many cases require removal of the inflamed appendix, either by laparotomy or laparoscopy. Untreated, mortality is high, mainly because of peritonitis and shock.

Signs and symptoms:

These include localized findings in the right iliac fossa. The abdominal wall becomes very sensitive to gentle pressure (palpation). Also, there is rebound tenderness. In case of a retrocecal appendix, however, even deep pressure in the right lower quadrant may fail to elicit tenderness (silent appendix), the reason being that the cecum, distended with gas, prevents the pressure exerted by the palpating hand from reaching the inflamed appendix.

Rovsing's sign:

Continuous deep palpation starting from the left iliac fossa upwards (anti clockwise along the colon) may cause pain in the right iliac fossa, by pushing bowel contents towards the ileocaecal valve and thus increasing pressure around the appendix. This is the Rovsing's sign.

Psoas sign:

Psoas sign is right lower-quadrant pain that is produced with the patient extending the hip due to inflammation of the peritoneum overlying the iliopsoas muscles and inflammation of the psoas muscles themselves. Straightening out the leg causes the pain because it stretches the muscles, and flexing the hip into the "fetal position" relieves the pain.

Obturator sign:

If an inflamed appendix is in contact with the obturator internus, spasm of the muscle can be demonstrated by flexing and internal rotation of the hip. This maneuver will cause pain in the hypogastrium.

Blumberg sign:

Deep palpation of the viscera over the suspected inflammed appendix followed by sudden release of the pressure causes the severe pain on the site indicating positive Blumberg's sign and peritonitis.

Alvarado score:

A number of clinical and laboratory based scoring systems have been devised to assist diagnosis. The most widely used is Alvarado score.

Symptoms
Migratory right iliac fossa pain	1 point
Anorexia	1 point
Nausea and vomiting	1 point
Signs
Right iliac fossa tenderness	2 points
Rebound tenderness	1 point
Fever	1 point
Laboratory
Leucocytosis	2 points
Shift to left (segmented neutrophils)	1 point
Total score	10 points

TREATMENT:

Surgery:

The surgical procedure for the removal of the appendix is called an appendicectomy (also known as an appendectomy). Often now the operation can be performed via a laparoscopic approach, or via three small incisions with a camera to visualize the area of interest in the abdomen. If the findings reveal suppurative appendicitis with complications such as rupture, abscess, adhesions, etc., conversion to open laparotomy may be necessary. An open laparotomy incision if required most often centers on the area of maximum tenderness, McBurney's point, in the right lower quadrant. A transverse or a gridiron diagonal incision is used most commonly.

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MYOCARDIAL INFARCTION

MYOCARDIAL INFARCTION

Myocardial infarction (MI) or acute myocardial infarction (AMI), commonly known as a heart attack, is the interruption of blood supply to part of the heart, causing heart cells to die.

Description:

This is most commonly due to occlusion (blockage) of a coronary artery following the rupture of a vulnerable atherosclerotic plaque, which is an unstable collection of lipids (fatty acids) and white blood cells (especially macrophages) in the wall of an artery. The resulting ischemia (restriction in blood supply) and oxygen shortage, if left untreated for a sufficient period of time, can cause damage or death (infarction) of heart muscle tissue (myocardium).Classical symptoms of acute myocardial infarction include sudden chest pain (typically radiating to the left arm or left side of the neck), shortness of breath, nausea, vomiting, palpitations, sweating, and anxiety (often described as a sense of impending doom). Women may experience fewer typical symptoms than men, most commonly shortness of breath, weakness, a feeling of indigestion, and fatigue. Approximately one quarter of all myocardial infarctions are silent, without chest pain or other symptoms.

Classification:

There are two basic types of acute myocardial infarction:

• Transmural: associated with atherosclerosis involving major coronary artery. It can be subclassified into anterior, posterior, or inferior. Transmural infarcts extend through the whole thickness of the heart muscle and are usually a result of complete occlusion of the area's blood supply.
• Subendocardial: involves small area in the subendocardial wall of the left ventricle, ventricular septum, or papillary muscles. Subendocardial infarcts are thought to be a result of locally decreased blood supply, possibly from a narrowing of the coronary arteries. The subendocardial area is farthest from the heart's blood supply and is more susceptible to this type of pathology.

Signs and symptoms:

Although chest pain or pressure is the most common symptom of a heart attack, heart attack victims may experience a variety of symptoms including:

• Pain, fullness, and/or squeezing sensation of the chest

• Jaw pain, toothache, headache

• Shortness of breath

• Nausea, vomiting, and/or general epigastric (upper middle abdomen) discomfort

• Sweating

• Heartburn and/or indigestion

• Arm pain (more commonly the left arm, but may be either arm)

• Upper back pain

• General malaise (vague feeling of illness)

• No symptoms (Approximately one quarter of all heart attacks are silent, without chest pain or new symptoms. Silent heart attacks are especially common among patients with diabetes mellitus.)

Risk factors:

Risk factors for atherosclerosis are generally risk factors for myocardial infarction:

• Diabetes (with or without insulin resistance) - the single most important risk factor for ischaemic heart disease (IHD)
• Tobacco smoking
• Hypercholesterolemia (more accurately hyperlipoproteinemia, especially high low density lipoprotein and low high density lipoprotein)
• High blood pressure
• Family history of ischaemic heart disease (IHD)
• Obesity^: (defined by a body mass index of more than 30 kg/m², or alternatively by waist circumference or waist-hip ratio).
• Age: Men acquire an independent risk factor at age 45, Women acquire an independent risk factor at age ; in addition individuals acquire another independent risk factor if they have a first-degree male relative (brother, father) who suffered a coronary vascular event at or before age. Another independent risk factor is acquired if one has a first-degree female relative (mother, sister) who suffered a coronary vascular event at age 65 or younger.
• Hyperhomocysteinemia (high homocysteine, a toxic blood amino acid that is elevated when intakes of vitamins B₂, B₆, B₁₂ and folic acid are insufficient)
• Stress (occupations with high stress index are known to have susceptibility for atherosclerosis)
• Alcohol Studies show that prolonged exposure to high quantities of alcohol can increase the risk of heart attack
• Males are more at risk than females.

Diagnosis:

A patient is diagnosed with myocardial infarction if two (probable) or three (definite) of the following criteria are satisfied:

1. Clinical history of ischaemic type chest pain lasting for more than 20 minutes
2. Changes in serial ECG tracings
3. Rise and fall of serum cardiac biomarkers such as creatine kinase-MB fraction and troponin

1. Physical examination 2. Electrocardiogram

3. Cardiac markers 4. Angiography

5. Histopathology

Prevention:

• Antiplatelet drug therapy such as aspirin
• Beta blocker therapy
• ACE inhibitor therapy should be commenced 24–48 hours post
• Statin therapy
• The aldosterone antagonist agent
• Omega-3 fatty acids,

Management:

1. Antiplatelet agents 2. Nitroglycerin

2. Reperfusion 4. Rehabilitation

Complications:

1. Congestive heart failure 2. Myocardial rupture

3. Arrhythmia 4. Pericarditis

5. Cardiogenic shock

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ANTIARRHYTHMIC DRUG SCHEME

β-Adrenoceptor antagonists (class II)
Clinical uses of class I antidysrhythmic drugs
• Class Ia (e.g. disopyramide)
o ventricular dysrhythmias
o prevention of recurrent paroxysmal atrial fibrillation triggered by vagal overactivity.
• Class Ib (e.g. intravenous lidocaine )
o treatment and prevention of ventricular tachycardia and fibrillation during and immediately after myocardial infarction.
• Class Ic
o to prevent paroxysmal atrial fibrillation (flecainide)
o recurrent tachyarrhythmias associated with abnormal conducting pathways (e.g. Wolff-Parkinson-White syndrome).
Clinical uses of class II antidysrhythmic drugs (e.g. propranolol, timolol )

• To reduce mortality following myocardial infarction.
• To prevent recurrence of tachyarrhythmias (e.g. paroxysmal atrial fibrillation) provoked by increased sympathetic activity.
Clinical uses of class III antidysrhythmic drugs
• Amiodarone: tachycardia associated with the Wolff-Parkinson-White syndrome. It is also effective in many other supraventricular and ventricular tachyarrhythmias but has serious adverse effects.
• (Racemic) sotalol combines class III with class II actions. It is used in paroxysmal supraventricular dysrhythmias and suppresses ventricular ectopic beats and short runs of ventricular tachycardia
Adenosine (unclassified in the Vaughan Williams classification)
Clinical uses of class IV antidysrhythmic drugs
• Verapamil is the main drug. It is used:
o to prevent recurrence of paroxysmal supraventricular tachycardia (SVT)
o to reduce the ventricular rate in patients with atrial fibrillation, provided they do not have Wolff-Parkinson-White or a related disorder.
• Verapamil was previously given intravenously to terminate SVT; it is now seldom used for this because adenosine is safer.

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