A.1 Hemodynamic Effect of Mitral Valve Commissurotomy in Patients with Mitral Stenosis

GLENNE. NEWMAN*, STEPHENK. RERYCH*, MARK T. UPTON*

and ROBERTH. JONES*, Durham, North Carolina

Sponsored by David C. Sabiston, Jr., Durham, North Carolina

The recent development of noninvasive radionuclide angiography has provided a means to assess multiple parameters of cardiac function with simplicity and accuracy and more importantly during maximal exercise. Left ventricular function was assessed by radionuclide angiocardiorgra-phy in 9 patients with isolated mitral stenosis before and approximately 6 months after mitral commissurotomy (MC). The mean mitral valve gradient was 14.0 ± 2.8 mmHg, and the mean mitral valve area was 1.20 1 0.26 cm². Each patient was evaluated at rest (R) and during maximal exercise (E) on an isokinetic bicycle ergometer before and after commissurotomy. Heart rate (HR), LV ejection fraction (EF), LV end-diastolic volume (EDV), pulmonary transit time (PTT), LV stroke volume (SV), cardiac output (CO) and diastolic ventricular filling rate (DVFR) were determined by the nuclide technique. Before operation patients with mitral stenosis had characteristic changes from rest to exercise which supported restriction to diastolic left ventricular filling as the primary limitation in generating a cardiac output during exercise. The SV was unchanged from rest to exercise because the EDV decreased (P < 0.05) and the EF increased (P <0.05). Thus, the CO during exercise was HR dependent. However, after commissurotomy the SV increased (P <0.05) from R to E because the EDV was unchanged and the EF increased (P < 0.05). Therefore, the CO during E was achieved by HR and an augmented SV. Moreover, the PTT was reduced during R (P<0.05) and E (P<0.05) after MC. The table reflects the differences during R and E and the paired-statistic (*P<0.05) before and after MC.

	At rest (preop)	At rest (postop)	Exercise (preop)	Exercise (postop)
HR	94 ± 16	90 ± 17	155 ± 21	159 ± 20
EF-%	51 ± 12	56 ± 7	61 ± 10	68 ± 10
EDV-ml	100 ± 24	133 ± 32*	84 ± 21	125 ± 43*
SV-ml	51 ± 16	75 ± 21*	51 ± 17	85 ± 27*
CO-L/min	4.7 ± 1.6	6.6 ± 1.8*	7.8 ± 2.4	13.7 ± 3.9*
PTT-sec	9.3 ± 2. 3	6.3 ± 1.2*	6.4 ± 1.4	3.6 ± 1.4*
DVFR-ml/sec	137 ± 52	194 ± 66*	235 ± 66	422 ± 176*

An increased EDV, SV, CO and DVFR and a decreased PIT are demonstrated at rest and during exercise after commissurotomy. The cardiac output rose from 6.6 L/min during exercise before operation to 13.7 L/min postoperatively. These differences in hemodynamic parameters at rest and druing exercise document the mechanics of increased tolerance in patients with mitral stenosis after mitral commissurotomy.

A.2 PEEP in the Management of the Post-Operative Bleeding Heart Patient

PATRICK) A. ILABACA*, JOHNL. OCHSNER, and

NOEL L. MILLS, New Orleans, Louisiana

This prospective study involves 406 consecutive adults who had heart surgery with extracorporeal circulation. Fifteen patients (3.7%) bled at the rate of 200 cc per hour or more in the post-operative period. Thirteen of the 15 patients who bled had had coronary surgery.

After checking and correcting all clotting parameters, and when applicable, hypertension, Positive End Expiratory Pressure (PEEP) was used in managing the bleeding of these patients. Initially, ten centimeters of PEEP were used; this was increased to 15 cm. in those cases in which ten did not sufficiently decrease the rate of hemorrhage. Before institution of PEEP, the average bleeding was 330 cc per hour for one to five hours. After PEEP was instituted in the 11 cases in which bleeding was controlled, an average output of 25 cc per hour for one to ten hours was recorded. Patients were kept on PEEP for five to ten hours. No patient rebled while weaning off PEEP.

In seven patients hemorrhage was controlled with 10 cm. of PEEP; four required 15 cm. of PEEP to stop bleeding; three were explored for continuous bleeding on 15 cm. of PEEP and one because she did not tolerate it. The bleeding sources in the four cases explored were; (1) a branch of a saphenous vein graft; (2) a branch of the internal mammary; (3) a large vein severed at the xiphoid; and (4) no definite site was found, but a large clot in the posterior descending graft suture line was seen at the time of surgery.

In 11 of the 15 patients who bled post-operatively (73%), surgery was avoided by judicious use of PEEP. We believe that PEEP increases mediastinal pressure and that the overdistended lung can obliterate some bleeders in the mediastinum, thus controlling bleeding in many of these patients. We conclude that PEEP is a valuable tool in the management of the post-operative bleeding heart patient.

*By invitation