Left Atrial and Pulmonary Capillary Venous Pressures in Mitral Stenosis

A method of measuring pulmonary " capillary " pressure by wedging a catheter into a terminal branch of a pulmonary artery was introduced by Hellems et al. in 1948.To differentiate this from pressures recorded in a blocked pulmonary vein (e.g. through an atrial septal defect) this pulmonary " capillary" pressure will be referred to as pulmonary capillary venous pressure (P.C.V.P.), follow- ing the lead of Lagerl6f and Werk6 (1949).Subsequent investigations have produced confficting evidence concerning the interpretation and accuracy of such pressure measurements, and this report presents the results of a new method used to investigate the relationship between P.C.V.P. and left atrial pressure.Dow and Gorlin (1950) found a close correlation between P.C.V.P. and left atrial pressure in dogs; the two pressures also varied directly under abnormal conditions.Several investigators have found the P.C.V.P. to be higher than the pressure in the left atrium, considerably so in some instances (Hellems et al., 1948, 1949; Lagerlof and Werko, 1949; Calazel etal., 1951; and Ankeney, 1952).Ankeney has recently questioned whether phasic variations in P.C.V.P. records reflect similar phasic pressure changes in the left atrium, and suggests that the true P.C.V.P. is essentially devoid of phasic variations.Opinion among investigators also varies with regard to the significance and interpretation of the waves seen in P.C.V.P. tracings.So far all published attempts to record pressures from a blocked pulmonary artery and from the left atrium simultaneously have been in dogs under general anmsthesia or in human subjects with atrial septal defect.In this investigation the problem has been tackled in the conscious human subject in the absence of a septal defect.Certain patients with mitral valve disease were selected for this study, in view of the practical importance of measuring the P.C.V.P. in that condition.It is common knowledge that the tracheal bifurcation and left atrium are in close proximity, and that an enlarged left atrium in mitral valve disease may widen the carina and compress the left main bronchus.Post-mortem examinations confirmed the fact, first demonstrated by Allison (1952) in this country, that a needle could be introduced through the left main bronchus into the left atrium without endangering any nearby vital structure.Method.After studying relevant anatomy in the cadaver, a No. 22 gauge needle, 5 cm.long, was selected for the left atrial puncture.The needle was attached to the distal end of a metal bronchoscopic suction tube.A polythene catheter inside the metal tube connected the needle to the recording machine.Fig. 1 illustrates the position of a three-way tap that provided the essential means of recording immediately consecutive pressures from the left atrium and from a blocked peripheral pulmonary artery.Cardiac catheterization was performed by the standard method of Cournand on the conscious patient 30 minutes after oral administration of 3 grains of sodium amytal and 0-5 grains of codeine phosphate.Heparin, 5000 units (50 mg.), was injected through the catheter.Pressures were recorded in mm.Hg. by means of a Sanborn electromanometer and a direct writing multichannel