Haemodynamic effects of atrial pacing in rheumatic mitral stenosis.

Abstract

Haemodynamic effects of right atrial pacing were studied in 12 patients (average age 25'6 years) with isolated rheumatic mitral stenosis in normal sinus rhythm. The cardiac output, systemic arterial pressure, and the left ventricular work did not change during atrial pacing. Both I966). Accordingly, the present investigation was designed to study the haemodynamic effects of increasing the heart rate by right atrial pacing in patients with rheumatic mitral stenosis. Subjects and methodsTwelve patients (7 men and 5 women) with isolated rheumatic mitral stenosis in normal sinus rhythm were studied. Their ages ranged between i6 and 34 years (average of 25 6 years). None of the patients had evidence of rheumatic activity as judged by the modified Jones criteria (I965). No one was receiving digitalis preparations for at least two weeks before the study. A right and percutaneous left heart catheterization study (Seldinger, I953) was performed in all in a fasting state Received 9 November I973. without any premedication, to assess the severity of mitral stenosis and to exclude mitral regurgitation. The nature of the procedure of right atrial pacing was fully explained to each patient and a written consent was taken for carrying out the procedure of atrial pacing in addition to right and left heart catheterization. Intracardiac pressures were recorded through P23 AA strain gauge transducers on a multichannel photographic recorder (DR-8 Electronic for Medicine Inc. U.S.A.). The baseline for all pressure measurements was taken as half the chest thickness at the second costal cartilage in the supine position (Roy, Gadboys, and Dow, I957).Cardiac output was estimated by a dye dilution technique (Hamilton et al., 1932). Indirect transmitral pressure gradients were obtained by simultaneous recording of pulmonary artery wedge pressure and left ventricular diastolic pressures using equisensitive preamplifiers with a common baseline. The precise point where left ventricular end-diastolic pressure was measured corresponded with the nadir of the atrial kick in the left ventricular tracing. In tracings where the atrial kick could not be clearly defined, the left ventricular enddiastolic pressure was measured at a point corresponding with the peak of the R wave in the surface electrocardiogram. A No. 6F NBIH bipolar catheter was introduced percutaneously through a venous dilator into the right femoral vein and positioned in the right atrium at a site where complete capture occurred during pacing with an extemal fixed rate pacemaker. Atrial pacing was performed at a minimum rate of 30 per cent above the resting heart rate. In 3 patients where the basal heart rate was less than go a minute, pacing was performed at two rates, one 30 per cent above the basal level and the other at the maximum rate of 140 a minute. All the haemodynamic variables were repeated during 8 to I0 minutes

Hemodynamic evaluation of stenotic cardiac valves: I. Effect of ventriculography and atropine on mitral stenosis

“…Rapid atrial pacing has been considered a valid alternative intervention, but this procedure has several disadvantages: An additional catheter for atrial stimulation is necessary and it is less effective than exercise since it does not induce any increase in CO because of a consistent decrease of stroke volume [8,9]. In addition, when atrial fibrillation is present, ventricular pacing has to be performed with its known CO reduction and consequently with its less marked increment in MVF [16, which is easily carried out by means of a bolus of i.v.…”

“…When baseline mitral gradient (MG) is low, and valve area is at least moderately reduced, physiological interventions raising heart rate (HR) and cardiac output (CO) should be routinely carried out and the induced changes on MG evaluated. Basically, exertion [5-71 and rapid atrial pacing [8,9] have been used. Such interventions have both advantages and limitations.…”

Hemodynamic evaluation of stenotic cardiac valves: II. Modification of the simplified valve formula for mitral and aortic valve area calculation

“…Their study showed a good linear correlation although in certain cases similar Gorlin values corresponded to markedly different Hakki values. The preliminary results found by these authors need further evaluation, particularly in patients with MS whose data are evaluated under varying conditions [4,5]. Furthermore, Hakki et a1 used 0.7 instead of 0.85 as a constant for MVA calculation when the latter value seems to be more correct.…”