'Cardiac' enzymes after transurethral resection of the prostate

TROPONIN T AND N-TERMINAL PRO-BRAIN NATRIURETIC PEPTIDE CHANGES IN PATIENTS UNDERGOING TRANSURETHRAL RESECTION OF THE PROSTATE

PURPOSE

We investigated whether transurethral resection of the prostate (TURP) caused subclinical myocardial damage or cardiac dysfunction by measuring troponin T (Trop T) and N-terminal pro-brain natriuretic peptide (pro-BNP).

MATERIALS AND METHODS

A total of 52 consenting patients took part in this study. All had a detailed medical history including cardiac history taken. On the day of the operation all patients had troponin T, pro-BNP, full blood count and urea, electrolytes and creatinine measured preoperatively. A preoperative and postoperative electrocardiogram was performed. Patients in renal failure were excluded from analysis. During the operations factors such as blood loss, operative time, tissue resected and fluid absorption were monitored. On postoperative day 1 all the previously mentioned tests were repeated.

RESULTS

Mean patient age was 71 years (range 52 to 85). Eight patients had a history of associated cardiac problems. Mean preoperative and postoperative hemoglobin were 14.1 gm/dl (range 10.5 to 17) and 13.3 gm/dl (range 9.9 to 16.2), respectively. None of the patients had significant (greater than 1,000 ml) fluid absorption during TURP, which was calculated using ethanol tagged glycine. Mean blood loss measured with a photometer was 129.7 ml (range 0 to 1,800). Mean operative time was 28.4 minutes (range 5 to 50) and mean weight of prostatic tissue resected was 15.2 gm (range 1 to 47). Preoperative Trop T was less than 0.01 mcg/ml in all patients and mean pro-BNP was 39.2 pg/ml (range 0.5 to 866). Postoperative Trop T was less than 0.01 mcg/ml in all but 1 patient who experienced chest pain after TURP and had an increased Trop T (0.28 mcg/ml). Mean postoperative pro-BNP was 54.57 pg/ml (range 1 to 679). A total of 37 patients had an increase in pro-BNP which was still within the reference range for the age group. There were no significant electrocardiogram changes postoperatively. The Trop T changes were not statistically significant (Wilcoxon sign ranked test p = 0.31) although they may be clinically significant.

CONCLUSIONS

Our study indicates that in patients with no prior cardiac history TURP does not cause myocardial damage indicated by nonincrease of Trop T. There are slight increases in pro-BNP after TURP in some patients although the exact clinical significance is uncertain.

Creatine kinase alterations after acute malignant hyperthermia episodes and common surgical procedures

Skeletal muscle may release creatine kinase (CK) during a malignant hyperthermia (MH) episode; however, muscle damaged during surgery may also release CK. This study examined the overlap between peak plasma CK levels in patients suspected of having had a MH episode (data obtained from North American MH Registry) and previously published CK changes occurring after common surgeries. For patients who were subsequently proven to be MH positive by muscle biopsy, there was considerable overlap. This was most significant with surgeries having substantial tissue damage, such as major vascular surgery and abdominal surgery. Overlap was much less with minimally invasive surgery, such as cystoscopy. Approximately 30% of MH positive patients treated with dantrolene had peak CK in the range of most surgical procedures, and approximately 50% of MH positive patients not given succinylcholine had peak CK similar to those of most surgical procedures. Dantrolene did not significantly alter peak CK in MH positive patients; however, succinylcholine was associated with significantly higher peak CK. These data suggest that patients who have had an acute MH episode during a surgical procedure may have peak CK values within the range of CK values expected from the procedure itself.