AORTIC VALVE INCOMPETENCE 55 



'manometer. Steadying the innominate by the thread (1) held in left hand, 

 cut with sharp fine scissors half through the innominate 4 mm. distal to 

 ligature-thread (3), which is still loose. Seize the right edge of the gaping cut 

 in the artery with fine forceps in left hand and pass into the artery towards 

 the heart the end of the wire stylet previously oiled. Loosen the most 

 proximal thread-loop and pass the wire down ; it will meet with obstruction 

 at the aortic valve. Feel with the finger for the seat of obstruction and 

 assure yourself that it is at the aortic orifice and that the wire has not passed 

 through into the ventricle. Press the wire down against the obstruction, support- 

 ing the aorta with the fingers of the other hand. The obstruction will be 

 felt to suddenly yield ; this means the breaking of a cusp of the valve. 

 Withdraw the wire a few millimetres and twist it a little in the aorta : thrust 

 it down again ; it will meet obstruction at the same level as before ; break this 

 down as before. Then at once withdraw the wire, drawing tight the ligature 

 (2) as the wire leaves the artery. 



VII. Replace the chest-wall flap over the opening in chest. Observe the 

 change in the kymograph record of the subclavian, and see that the connecting- 

 tube and cannula have not been shifted from the favourable position in which 

 they lay before the innominate was dealt with. The cardiac pulsations have 

 become much more marked, although the systolic maximum has altered little 

 (text-figs. 26, 27). The pulsations will increase in depth still further, though the 

 mean pressure may not fall much. The aortic regurgitation accentuates the 

 pulse-waves by causing the diastolic pressure of each pulse-wave to fall 

 abnormally low (water hammer-pulse of aortic insufficiency). A further effect 

 which often occurs is considerable irregularity of the pulse-frequency, also a 

 reduction of the pulse-rate. In this latter case the slowing of the pulse-rate 

 tends of itself to increase the pulse oscillations, especially with a Hg manometer 

 record. Note the change in the pulse-form (text-fig. 27). The auricular 

 systole may make itself felt as a pressure rise in the aorta (text-fig. 27). 



VIII. Tie off the left subclavian artery permanently by ligating with 

 the controlling proximal thread already round it. Clamp the junctional tube 

 to manometer. Detach the junctional tube from the subclavian cannula. 

 Shift the operation table somewhat from the kymograph. The calibration of 

 the membrane manometer and the actual inspection of the aortic valve-lesion 

 produced remain to be done. These do not require the living preparation 

 and are deferred to the end of the exercise ; see § X. 



IX. Have ready a 50 c.c. burette clamped to a standard and armed Obs. 38. 



below with about 20 cm. rubber tubing with pinch-cock, 30 c.c. of -2 per cent, i^ed^ciiig 



action of the 



