Dobutamine stress echocardiography for CHD

Dobutamine is a similar chemical that our bodies produce when our physical activity levels increase. It acts to:
1. increase heart rate
2. increase the force of the contraction.

Indications for this type of stress test are to see if a patient has evidence to support a diagnosis of CHD, to determine whether a patients symptoms are due to a cardiac problem and to check the efficiency of medical treatments for CHD.

Patients are prescribed this kind of stress test if they have contraindications for a normal excercise test. i.e. lung disease, severe arthritis or sever PVD.

The procedure involves;
1. an IV infusion of dobutamine.
2. the placement of 10 electrodes strategically on the chest and connected to an ECG machine.
3. blood pressure monitor throughout the test.
4. an initial ultrasound image of the heart at rest.
5. IV infusions od the drud at regular intervals with ultrasound images taken periodically until the IV has stopped. usually only 4 images in total.

these ultrasound images and ECG tracings are then used for the diagnosis of a cardiac problem.



HYPERFIBRINOGENAEMIA is defined as the increase of fibrinogen (a plasma protein) in the blood. It is a biochemical risk factor for CHD.



The contraindications for the use of beta blockers include:
cardiogenic shock
hypotension
bradycardia <50
active asthma
sever respiratoy disease

usually ACE inhibitors and beta blockers are given insync as a combined therapy to which most patients are administed if they can tolerate them. However an ACE inhibitor can be given alone instead. It acts to also improve the hemodynamics of the heart by decreasing preload and afterload with vasoconstriction of the coronary arteries. ( It also blocks angiotensin 2 formation and increase nitric oxide production. This in turn reduces the inflammatory process post a cardiac event.

For example, beta blockers increase bp. fewer patients have a low bp and can tolerate beta blockers and ace inhibitors. However a patients condition has to be evaluated first. I a patient has renal insufficiency and restricted ventricular function they would need beta blockers. But if a patient had DM, with decreased ventricular function and bronchospasmic disease, then giving an ace inhibitor alone may be prudent.


hope this helps!!
jess