Ventricular pressure tracing vs arterial pressure tracing
The diastolic pressure is very low in a ventricular pressure tracing, compared to an arterial pressure tracing. But the arterial pressure tracing can have a low diastolic pressure in aortic regurgitation. Ventricularization of a coronary artery pressure tracing can occur when the engagement of the catheter is not proper and produces wedging of the catheter within the artery. Wedging is more likely in an artery with ostial stenosis or when a larger sized catheter than the artery is used.
Aortic pressure tracing vs femoral arterial pressure tracing
Upstroke and downstroke are sharper in a peripheral arterial pressure tracing compared to the central aortic pressure tracing. Amplitude is higher in a peripheral tracing due to amplification of the pressure wave. The dicrotic notch in the peripheral arterial tracing will be lower compared the incisura of the aortic pressure tracing. The differences are due to the higher resistance in the periphery and the presence of the reflected wave. While measuring ventricular and arterial pressure simultaneously, if a single sheath is being used, the sheath diameter has to be significantly larger than that of the catheter.
Ventriculo-arterial pressure gradient
It is usually the peak to peak gradient which is measured from pressure tracing while Doppler measures the peak instantaneous gradient. Mean pressure gradient can be assessed by planimetry from the ventricular and arterial pressure gradient. Mean gradient will be about two third of the peak to peak gradient.
Carabello sign / effect
On LV (left ventricle) to aorta pull back, aortic pressure rises due to relief of the enhanced obstruction of the aortic orifice which had occurred while entering the LV in severe aortic stenosis.
What is the diameter of a 6 F catheter?
6 F catheter will have a diameter of about 2 mm (0.33 mm per 1 F).
What is the phenomenon of pressure recovery in aortic stenosis?
Systolic pressure in the aorta will be lower immediately distal to the valve, while it ‘recovers’ to a higher value more distally in the aorta. Hence gradient measured by catheter will be lower than what is measured by Doppler, even after accounting for the difference between peak to peak gradient and peak instantaneous pressure gradient. The lower pressure near the valve is due to the effect of the jet which causes a reduction in the lateral pressure. To get the recovered pressure (settled pressure), catheter has to be pulled back about 2 to 3 cm beyond the sino-tubular junction.