Ultrasonic Cardiac Output Monitor

Ultra-Sonic Cardiac Output Monitor

ULTRA-SONIC CARDIAC OUTPUT MONITOR

15 /3 /08

Ultra-sonic Cardiac Output Monitor

Cardiac outputs and cardiac filling pressure measurements are invaluable for early diagnosis of heart failure , monitoring of disease progression , prognosis of therapy and during cardiac surgery Differentiation of cardiac and pulmonary dyspnoea , optimisation of the Atrio-

Ventricular intervals , outpatient monitoring , evaluation of rejection in a heart transplant , optimisation of fluid in patients with congestive failure , monitoring the response in teatment of drug resistant hypertension and cardiac arrhythmias are some of the indications for

br cardiac output estimation . Patients undergoing biventricular pacemaker implantation also need their cardiac output estimated . Many of these indications are seen in the emergency department . The balance between life and death is decided by the speedy response of the doctor to the crisis

Current methods are expensive , difficult to operate and provide variable results . They are the Fick method , thermodilution and thoracic electric bioimpedance , ECG ( electrocardiogram

and invasive transoesophageal echocardiographic ventricular transections . All are invasive except for the thoracic electric bioimpedance . All provide an idea of the stroke volume and haemodynamics involved . The ECG however gives only an indirect measurement of the cardiac muscle conductivity and not the blood flow . The thoracic electrical bioimpedance technique is safe , reliable and noninvasive However patients have to be apneic and motionless . Hence its usefulness is questionable (Muzi et al , American Physiological Society

The Ultra sonic cardiac output monitor was manufactured by an Australian company , the USCOM Ltd in 2002 . The aim was to provide the front-line clinician a stand-alone device to measure and monitor cardiac output . It employs a method slightly different from conventional techniques like thermodilution which is an invasive process by which a flexible catheter is inserted into preformed vessels connected to the heart like the aorta and pulmonary artery . The distal end is within the body and the proximal end is outside . The older technique used 2 catheters . All these are not appealing to a patient ( For the thermodilution method of determining cardiac output

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The necessity of a reliable non invasive method of repeatedly assessing the cardiac output

has been satisfied by the USCOM . The Ultra-sonic cardiac output monitor (USCOM ) is a device for monitoring the atrio-ventricular interval optimisation in cardiac resynchronisation therapy . It is a 2 dimensional echo-dependent continuous wave Doppler device . It does away with the invasive method . Essentially the parts are the ultrasonic transducer probe and a computer system to process the signals into cardiac parameters

The flow probe is a piezo-electric CW Doppler ultra-sound probe which uses a wide acoustic beam to track the blood flow through the aorta and even the pulmonary artery . The probe is placed outside the body , making the procedure non-invasive and convenient to the patient . This external probe determines signals from the aorta and pulmonary artery which convey the cardiac output information by processing the signals to decide physiological parameters associated with the heart . The parameters are transaortic peak velocity , mean transvalvular pressure gradient , stroke volume , time velocity integral , cardiac output or...