HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Personal Folders Download to citation manager Permission Requests Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Walters, F. J. Articles by MacGregor, D. C. Search for Related Content PubMed PubMed Citation Articles by Walters, F. J. Articles by MacGregor, D. C.

The Journal of Thoracic and Cardiovascular Surgery, Vol 78, 319-330, Copyright © 1979 by The American Association for Thoracic Surgery and The Western Thoracic Surgical Association

ARTICLES

Intramyocardial pH as an index of myocardial metabolism during cardiac surgery

FJ Walters, GJ Wilson, DJ Steward, RJ Domenech and DC MacGregor

At present, a practical method for continuous monitoring of the state of tissue metabolism in the individual patient's heart during cardiac operations is not available. We have explored the use of miniature electrode measurements of myocardial interstitial pH to provide this monitoring capability, making comparisons with intracellular pH in left ventricular biopsy specimens and with tissue PCO2 measured by mass spectrometry. The electrode system consisted of a hydrogen ion- sensitive glass miniature electrode, housed in the beveled end of a 21 gauge (0.8 mm diameter) hypodermic needle, and a 2 mm diameter reference electrode, with an internal silver-silver chloride electrode coupled to tissue through a saline bridge (150 mM/L sodium chloride) saturated with silver chloride. Accuracy in blood at 37 degrees C was compared with conventional instrumentation (Radiometer BMS-3 MK-2 Blood Micro System) over a pH range of 7.4 to 6.4 with linear regression analysis (n = 26) revealing a high correlation (r = 0.997) and a mean difference in paired observations of only 0.01 +/- 0.004 (mean +/- SEM) pH units. In two groups of dogs on cardiopulmonary bypass, the pH needle and reference electrodes were inserted into the anterior wall of the left ventricle. Ischemic arrest of the heart at 37 degrees C was used to vary myocardial pH. In Group 1 (n = 8), intracellular pH was estimated from left ventricular biopsy specimens (400 mg each) taken over a microelectrode pH range of 7.37 to 6.37, snap frozen, and homogenized. In Group II (n = 6), tissue PCO2 in the anterior wall of the left ventricle was determined by mass spectrometry (sampling catheter 1.3 mm diameter). Miniaturized electrode (interstitial) pH exceeded biopsy (intracellular) pH under control conditions by 0.28 +/- 0.025 pH units (p less than 0.001), but below an electrode pH of 6.8 the results of the two techniques did not differ significantly. The tissue PCO2 rose from 69 +/- 2 mm Hg to a final plateau of 419 +/- 25 mm Hg, which was similar to the predicted value of 427 +/- 28 mm Hg calculated from the pH change (7.37 +/- 0.01 to 6.01 +/- 0.07), providing a further independent check on the pH electrode technique. These data indicate that our intramyocardial pH measurements do reflect intracellular metabolism during elective arrest of the heart and may have potential for clinical use.

This article has been cited by other articles:

				A.C.L. Graffigna, G. Nollo, C. Pederzolli, P. Ferrari, L. Widesott, and R. Antolini Continuous monitoring of myocardial acid-base status during intermittent warm blood cardioplegia Eur. J. Cardiothorac. Surg., June 1, 2002; 21(6): 995 - 1001. [Abstract] [Full Text] [PDF]

				Y. K. Skrobik and J. G. Filep Epi and endomyocardial pH allows the detection of acute right ventricular ischemia in pigs: a new evaluation method: [La connaissance des pH epimyocardique et endomyocardique permet la detection d'ischemie aigue du ventricule droit chez des porcs : une nouvelle methode d'evaluation] Can J Anesth, January 1, 2002; 49(1): 84 - 89. [Abstract] [Full Text] [PDF]

				K. R. Khabbaz, F. Zankoul, and K. G. Warner Intraoperative metabolic monitoring of the heart: II. Online measurement of myocardial tissue pH Ann. Thorac. Surg., December 1, 2001; 72(6): S2227 - 2233. [Abstract] [Full Text] [PDF]