The Annals of Thoracic Surgery, Vol 42, 619-626, Copyright © 1986 by The Society of Thoracic Surgeons
Acute rejection after cardiac transplantation: detection by interstitial myocardial pH
TJ Takach, LR Glassman, ER Rodriguez, JT Falcone, VJ Ferrans and RE Clark
Intramyocardial pH was assessed as a potential marker for clinical
evaluation and treatment of acute rejection following cardiac
transplantation. Fifteen cats underwent forty operative procedures.
Following intra-abdominal heterotopic heart transplantation, serial
laparotomies were performed in the early (days 0 to 2), intermediate (days
5 to 7), and late (days 7 to 16) postoperative periods. Rejection was
assessed by serial clinical examinations, ECG analyses, B-mode
echocardiography, histological and ultrastructural analyses, and
measurements of interstitial myocardial pH. Intramyocardial pH was measured
by a new miniature (0.6 X 3.0 mm) fiberoptic pH transducer. At confirmed
rejection, concomitant laparotomy and thoracotomy were performed and pH
sensors were implanted in both native (anatomical) and graft hearts. Nine
animals at rejection were given methylprednisolone and changes in graft and
native heart pH were measured. The pH during absence of rejection, mild
acute rejection, and severe acute rejection averaged 7.430 +/- 0.019, 7.233
+/- 0.040 (p less than .02), and 6.860 +/- 0.066 (p less than .02),
respectively (mean +/- standard error of the mean). A progressive decline
in pH was noted in each heart. In animals receiving steroids, graft heart
pH increased over 90 minutes from 6.852 +/- 0.065 to 7.043 +/- 0.077 (p
less than .05). Although pH decline may be secondary to either inflammatory
or ischemic etiology, histological and ultrastructural analyses demonstrate
a predominant inflammatory response with progressive mononuclear cell
infiltration, interstitial edema, vascular wall edema, infiltration by
polymorphonuclear neutrophil leukocytes, vacuolation of sarcoplasmic
reticulum, and disarray of myocytes associated with falling pH. Degree of
pH change correlated closely with degree of histological rejection,
presence of ECG voltage decline, and change in wall thickness by
ultrasound.