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Myocardial metabolism during cardioplegia for aortic valve replacement
Et feet substrate Department Karolinska
of
a new stimulator of metabolism in healthy of Clinical Physiology
carbohydrate metabolism men.L.Kaijser,B.Berglund and Gustaf V Research
on
myocardiai and L.A.Carlso Institute,
sjukhuset,Stockholm,Sweden.
Plasma free fatty acids (FFA)constitute the major substrate of myocarfor a given ener-gy yield lipid oxidial oxidative metabolism. However, dation requires more oxygen than carbohydrate oxidation. Thus, the induction of a relative increase in carbohydrate utilization may be bcneficial in myocsrdial ischemia. This may be achieved by i.v. q!ucose infusion, drugs lowering plasma FFA concentration or drugs with intraimyocardial effects on enzymes of the intermediary metabolism e.g. pyruvatedehydrogenase (PDH). Myocardial extraction of oxygen, carbohydrate substrates and FFA was measured in helthy volunteers by catheterisation of an artery and the injection of (S)-4-hydroxyphenylcoronary sinus before and after i.v. glycine
(HPG),
which
is
assumed
to
act
mainly
extraction and oxidation was estimated by i.v. HPG increased myocardial RQ from 0.75 to 0.90, predominantly lipid to predominantly carbohydrate extractions of glucose and lactate were doubled. was only slightly reduced, but FFA fractional accordance with the RQ change. It is concluded hydrates oxidation in man can be increased by intramyocardiat enzymes.
MYOCARDIAL L. Kaijser. Physiology
METABOLISM W. Bomfin, and Thoracic
Stockholm,
Sweden.
DURING CARDIOPLEGIA E. Jansson and C. Surgery, Karolinska
by
PDH activation. FFA 14C oleate. infusion of indicating a shift from oxidation. Myocardial The extraction of FFA oxidation decreased in that myocardial carboa agent which effects
FOR AORTIC VALVE Olin. Departments sjukhuset, S-104
REPLACEMENT. of Clinical 01
Hypothermic cardioplegia has become the standard method for myocardial preservation during open heart surgery, but little is known about the merits of different cardioplegic solutions. In 23 patients undergoing aortic valve replacement in extra corporeal circulation cardioplegia was induced by infusion of 700-1000 ml cooled Ringers acetate containing 20 mM K+ into the left coronary artery, resulting in a myocardial temperature of 20°C. Simultanous blood samples from an artery and the coronary sinus were taken before and at intervals for 60 min after! and biopsies were taken at the onset and immediately after cardioplegra. Immediately after cardioplegia a substantial net release of lactate was found. Myocardial glycogen content had decreased 30 mM and lactate content increased 26 mM/kg dw. Myocardial glucose extraction was increased fivefold above basal, and while the lactate release gradually decreased the high glucose extraction remained, singifying a restoration of the glycogen stores. The increased glucose extraction was probably partly the result of increased arterial glucose concentration, but stimulated glycogen synthesis must have contributed. A low a-cs oxygen difference remained 60 min after cardioplegia suggesting disturbed distribution of myocardial blood perfusion.
of
a new stimulator of metabolism in healthy of Clinical Physiology
carbohydrate metabolism men.L.Kaijser,B.Berglund and Gustaf V Research
on
myocardiai and L.A.Carlso Institute,
sjukhuset,Stockholm,Sweden.
Plasma free fatty acids (FFA)constitute the major substrate of myocarfor a given ener-gy yield lipid oxidial oxidative metabolism. However, dation requires more oxygen than carbohydrate oxidation. Thus, the induction of a relative increase in carbohydrate utilization may be bcneficial in myocsrdial ischemia. This may be achieved by i.v. q!ucose infusion, drugs lowering plasma FFA concentration or drugs with intraimyocardial effects on enzymes of the intermediary metabolism e.g. pyruvatedehydrogenase (PDH). Myocardial extraction of oxygen, carbohydrate substrates and FFA was measured in helthy volunteers by catheterisation of an artery and the injection of (S)-4-hydroxyphenylcoronary sinus before and after i.v. glycine
(HPG),
which
is
assumed
to
act
mainly
extraction and oxidation was estimated by i.v. HPG increased myocardial RQ from 0.75 to 0.90, predominantly lipid to predominantly carbohydrate extractions of glucose and lactate were doubled. was only slightly reduced, but FFA fractional accordance with the RQ change. It is concluded hydrates oxidation in man can be increased by intramyocardiat enzymes.
MYOCARDIAL L. Kaijser. Physiology
METABOLISM W. Bomfin, and Thoracic
Stockholm,
Sweden.
DURING CARDIOPLEGIA E. Jansson and C. Surgery, Karolinska
by
PDH activation. FFA 14C oleate. infusion of indicating a shift from oxidation. Myocardial The extraction of FFA oxidation decreased in that myocardial carboa agent which effects
FOR AORTIC VALVE Olin. Departments sjukhuset, S-104
REPLACEMENT. of Clinical 01
Hypothermic cardioplegia has become the standard method for myocardial preservation during open heart surgery, but little is known about the merits of different cardioplegic solutions. In 23 patients undergoing aortic valve replacement in extra corporeal circulation cardioplegia was induced by infusion of 700-1000 ml cooled Ringers acetate containing 20 mM K+ into the left coronary artery, resulting in a myocardial temperature of 20°C. Simultanous blood samples from an artery and the coronary sinus were taken before and at intervals for 60 min after! and biopsies were taken at the onset and immediately after cardioplegra. Immediately after cardioplegia a substantial net release of lactate was found. Myocardial glycogen content had decreased 30 mM and lactate content increased 26 mM/kg dw. Myocardial glucose extraction was increased fivefold above basal, and while the lactate release gradually decreased the high glucose extraction remained, singifying a restoration of the glycogen stores. The increased glucose extraction was probably partly the result of increased arterial glucose concentration, but stimulated glycogen synthesis must have contributed. A low a-cs oxygen difference remained 60 min after cardioplegia suggesting disturbed distribution of myocardial blood perfusion.