Hypertension: 

This is a common disease especially when you get older. It is estimated that more than 60 million people in the USA has hypertension. The limit of hypertension is usually defined as the systolic blood pressure more than 140mmHg and the diastolic blood pressure more than 90mmHg. The aetiology of hypertension is usually unknown though a family history may be positive, other causes include renal disease (chronic renal failure, renal artery stenosis, acute inflammation of the kidney, polycystic kidney disease, etc.), endocrine diseases (e.g. Cushing syndrome), pregnancy related, oral contraceptive pills and others. Hypertension is associated with diabetes mellitus, coronary artery disease and arteriosclerosis.
Complications of hypertension includes hypertensive heart disease (in which the heart muscle increase in size with the heart becoming hypertrophied and later get ischemic and failed), renal impairment, haemorrhage of the brain (stroke), ischemic heart disease (angina and myocardial infarction) and eye disease (retinal haemorrhage).
 

Non-drug treatment of hypertension includes weight loss, optimal exercise, quit smoking and alcohol, low salt diet, decrease stressful life style, treatment of other associated disease like diabetes, coronary heart disease (CAD) and renal disease.

Drug treatment include various combination of beta blockers, diuretics, angiotensin converting enzyme inhibitors (ACEI), calcium channel blockers (CCB, especially long acting ones), alpha blockers, vasodilators.

As hypertension is a slowly developing and progressing disease, a long term follow up and treatment program is thus required for optimal management of this disease.

Coronary Artery Disease (CAD)
- Angina and Acute Myocardial Infarction
As our diet become more high cholesterol and saturated fat containing, our vessel get more easily narrowed because of the deposition of these fatty materials alongside the vessel wall. This process results in arteriosclerosis. Studies has shown that a high LDL (low density lipoprotein) level is directly related to high risk of arteriosclerosis. A high HDL (high density lipoprotein) level is associated with a protective effect for the development of coronary artery disease. A high triglyceride level is also found to be related to the development of CAD.
The formation of the fibrofatty plaque on the inside of the vessel wall results in progressively narrowing of the lumen. This results in decreased amount of oxygenated blood flow to the heart. The patient may have angina during exercise (dull central chest discomfort of a gripping nature and typically radiated to the neck, jaw and left shoulder) and later even at rest! If this fibrofatty plaque ruptures and bleeding results, platelets and other coagulation factors will deposit on the cracks resulting in a sudden blockage of the vessel supply specific region of the heart. This will result in acute myocardial infarction (heart attack). The typical symptoms is a severe dull central gripping pain which may also radiated to the neck and shoulder and lasting for more than 30 minutes associated with sweating, dizziness and even collapse and death. As the area of muscle supplied by that specific vessel is dead, recovery depends strongly on the area affected and the time to recannalisation of the blocked vessel.

The complication of CAD includes limitation of the daily activity due to the exertional angina, progressive deterioration of the heart function resulting in heart failure, acute myocardial infarction, cardiac arrhythmia, cardiac rupture and even death.

Diagnosis of acute myocardial infarction include the typical history of pain, ECG findings of hyper-acute ST segment elevation and serial changes, serial changes of cardiac enzymes (CK, CKMB, AST, LD) and other imaging techniques like thallium scanning.

Pre-operative assessment of patient with coronary artery disease is also very important so as to minimise the operative risk.

Non-drug treatment of CAD includes removal of risk factors (like smoking, obesity, sedentary life style, high blood cholesterol), treatment of aggregating diseases (hypertension, heart failure, tachycardia, valvular heart disease, anaemia, etc.).

Drugs treatment of CAD include aspirin, nitrates (sublingual and oral), calcium channel blockers, beta blockers. Internventional treatment for CAD include percutanous transluminal coronary angioplasty (PTCA) with or without stenting (including drug eluting stent), coronary artery bypass grafting (CABG) and transmyocardial revascularization (TMR).

Treatment of acute myocardial infarction include complete bed rest, oxygen, aspirin, morphine, thrombolytics (drugs to dissolve the clots in the vessel), heparin, nitrates, beta blockers, ACEI and may be calcium channel blockers and emergency PTCA. Long term management includes reduction of risk factors and cardiac rehabilitation (Quit smoking, treat high blood cholesterol, control hypertension and diabetes mellitus).
 

Cardiac Arrhythmias and Heart Blocks

As the normal beating of the heart requires the generation of a very small electrical impulse from the sinus node (SA node) in the right atrium and then spread through the conducting muscles of the atriums to the atrio-ventricular node (AV node) and then with some delay to the His-Purkinje system and the bundle branches where it spread to the muscles of the ventricles. Any problem along this pathway will result in bradycardias and heart blocks. If for some reasons, the automaticity of the cell of these structure is abnormal or there is a re-entry circuit somewhere (e.g. with an accessory pathway) or there are delay repolarizations of the electrical impulse (due to drugs or electrolyte disturbance), there will be tachyarrhythmias, i.e. abnormal fast or irregular heart beats.

The patients suffering from the above problems will have fast or irregular palpitations, drop beats, dizzy spells, syncope, loss of consciousness, angina, sweating, shortness of breath, polyuria or even sudden death.

The investigation of these patients includes ECG (electrocardiogram), CXR (chest X-Ray), blood investigation, 24 hours ECG (Holter) monitoring, treadmill exercise testing and Electrophysiological Study of the Heart (EPS).

Treatment include antiarrhythmics (Class I-IV e.g. quinidine, procainamide, flecanide, propafenone, lignocaine, propranolol, amiodarone, sotalol, etc.), placement of a Permanent Cardiac Pacemaker, EPS study and radio-frequency ablation (RF), implantation of a automatic cardioverter defibrillator (AICD), atrial cardioverter and other surgical techniques (e.g.MAZE procedure).
 
 

Cardiac Transplantation

The use of the cadaveric heart transplantation started in the 1960's. Since then, there is gradual increase in the number of transplantations to approximately 2000-3000 per year. As the development of a better immunosuppressive therapy with cyclosporin A, prednisone and azathioprine, the 5 year survival has increased to 80-90%. The most important is the limited donor supply. The cadaveric donor should be relatively young, with no systemic illness, infections or cardiomyopathy. The optimal recipient should be mentally sound, has no other end organ damage, systemic illness or infection.

The operative procedure involves the removal of the recipient's heart leaving the posterior walls of both atria and then suturing the donor's heart to the atria walls which are connected to the veins, the aorta and the pulmonary artery. As the heart is denervated, the patient will not have angina.

After the procedure, the patient will need to ne follow up regularily and to be put on drugs to suppress rejection. (e.g. Cyclosporin A, steroids, etc.)

Complications of this procedure include operative risks, rejection of the heart, accelerated coronary arteries stenosis and side effects of immunosuppression (like infection).
 
 

Vasovagal Syncope 
(Neurocardiogenic Syndrome)

This is a relatively common syndrome seen in young people especially females. The clinical setting is usually when the patient stands for a prolong period of time in a crowded environment e.g. inside a bus, train or underground railway system. He or she may feel dizzy, shortness of breath, "black screen" in front of the eyes and then feel to the ground with a brief period of loss of consciousness. This is usally a benign situation and the patient will be awake in a few seconds to minutes time. If you examine the patient during that time, he or she will usually has hypotension and bradycardia (slow heart rate). The situation will be dangerous if the patient happened to be in a pay phone stand where he or she cannot lie flat on the ground, as a result, continue hypotension may need to serious consequences.

The underlying mechanism of this syndrome is still unknown. It may be due to the hypersensitivity of the sympathetic nervous system what result in a over reaction and produce the slowing of the heart rate and/or lowish blood pressure.

Investigation will be mainly to exclude other causes of syncope (e.g. arrhythmias, drugs, epilepsy, etc.) and the Tilt Table Test will be useful for the documentation of this syndrome.

Treatment include beta-blockers, mineralcorticoides or even permanent pacemaker insertion for those if severe cardioinhibtory effect (profound bradycardia or asystole during attack).

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