Category Archives: Cardiovascular disease

Drug treatment

If physical manoeuvres have not been successful, intravnous adenosine (up to 0.25 mg kg-I) may be tried. This is a very short-acting (half-life < 10 s) naturally occurring purine nucleoside that causes complete heart block for a fraction of a second following intravenous admllllstratlOn (Usual dose in adUIt 3 mg; maximum 12 mg). It IS hjgb.1y effective at terminating junctional tach cardias or reveing atri

Cardiac arrhythmias

Junctional tachycardia Almost all junctional tachycardia is paroxysmal in nature. There is usually no associated structural disease but there may be demonstrable electrophysiological or electrocardiographic abnormalities such as the Wolff- ..Parkinson-White syndromeor the Lown-Ganong-Levine syndrome (in which there is an anomalous connection between the atrium and the bundle oTHis). There are two main varieti

Temporary pacing

Symptomatic bradycardias unresponsive to atropine are treated with a cardiac pacemaker. A temporary pacemaker (external unit) may be connected to the myocardium by a thin (French gauge 5 or 6), bipolar pacing electrode wire inserted via a subclavian or internal jugular vein and manipulated into the right ventricular apex using cardiac fluoroscopy. The energy needed for successful pacing (the pacing threshold

Therapeutic procedures

Cardiac resuscitation No matter where cardiac arrest occurs it is essential that someone close to the victim institutes basic life support. The longer the period of respiratory and circulatory arrest, the less the possibility of restoring healthy life. After 3 min there will be permanent cerebral dysfunction. Because sudden unexpected cardiac arrest is relatively common in the hospital, medical students and a

Nuclear imaging

Nuclear imaging techniques are primarily used in ischaemic heart disease. Myocardial structure and function can be assessed by radionuclide-irnaging techniques. Thallium-20l imaging This is used to detect myocardial ischaemia and infarction. Thallium, which behaves lilee potassium, is talcen up by healthy myocardium. Ischaemia or infarction produces a nuclear image with a ‘cold’ spot. The isotope

Echocardiography

Echocardiography uses echoes of ultrasound waves to map the heart and study its function. To provide detailed images, ultrasound wavelengths of 1 mm or less are used, which correspond to frequencies of 2 MHz (1 MHz = 1 000000 cycles s’) or more. At such high frequencies, the ultrasound waves behave more like light and can be focused into a ‘beam’ and aimed at a particular region of the hear

ECG waveform

The shape of the normal ECG waveform  has important similarities, whatever the orientation. The first deflection is caused by atrial depolarization, and it is a low-amplitude slow deflection called a P wave. The QRS complex results from ventricular depolarization and is sharper and larger in amplitude than the P wave. The T wave is another slow and low-amplitude deflection that results from ventricular repo

Cardiac investigation

Chest X-ray This is taken in the postero-anterior (p A) direction at maximum inspiration with the heart close to the X-ray film to minimize magnification with respect to the thorax. A lateral may give additional information if the PA is abnormal. The cardiac structures and great vessels that can be seen on these X-rays are indicated. Heart size Heart size can be reliably assessed only from the PA chest film;

Prosthetic sounds

Mechanical replacement heart valves produce loud clicks due to the opening and closing of the valve. These prosthetic sounds may be muffled or absent if valve movement is impeded by thrombus or vegetations. Heart murmurs Turbulent blood flow causes heart murmurs. Turbulence may be produced when there is high blood flow through a normal valve, or when there is normal blood flow through an abnormal valve or int

Heart sounds

THE FIRST HEART SOUND. This is caused by the closure of the mitral and tricuspid valves and is best heard at the cardiac apex. The sound is usually single but may be slightly split. If split, this ‘double’ sound at the beginning of systole must be distinguished from the combination of the first heart sound with a fourth heart sound or with an ejection click. The first heart sound is loud when the