The effects of cardioplegic arrest and reperfusion on the microvasculature of the heart

• Published in: European journal of cardio-thoracic surgery 1997-02, Vol.11 (2), p.350-357
• Main Authors: PATHI, V. L, MCPHADEN, A. R, MORRISON, J, BELCHER, P. R, FENNER, J. W, MARTIN, W, MCQUISTON, A.-M, WHEATLEY, D. J
• Format: Article
• Language: English
• Subjects: Anesthesia; Anesthesia depending on type of surgery; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Animals; Biological and medical sciences; Cardiopulmonary Bypass; Coronary Circulation - physiology; Coronary Vessels - pathology; Heart Arrest, Induced; Lymphocyte Depletion; Medical sciences; Microcirculation - pathology; Microscopy, Electron, Scanning; Myocardial Reperfusion Injury - pathology; Myocardium - pathology; Swine; Thoracic and cardiovascular surgery. Cardiopulmonary bypass
• ISSN: 1010-7940; 1873-734X
• DOI: 10.1016/S1010-7940(96)01037-8

OBJECTIVES: Despite laboratory evidence of leucocyte involvement inreperfusion injury, cardiac surgical clinical trials do not support thetherapeutic effectiveness of leucocyte filtration. Furthermore, the directeffects of crystalloid cardioplegia and reperfusion on the capillaries ofthe heart have yet to be elucidated. We tested the effects of cardioplegicarrest and reperfusion both with and without leucocyte depletion, in amodel of cardiopulmonary bypass that mimics clinical cardiac surgicalconditions. METHODS: Four groups of Landrace pigs were studied. Group A (n= 6) underwent 30 min of hypothermic (28 degrees C) cardiopulmonary bypass.Groups B (n = 6), C (n = 6) and D (n = 6) also had 90 min of cardioplegicarrest. Group C was then reperfused with whole blood, while Group D wasreperfused with leucocyte-depleted blood. Microvascular methylmethacrylatecorrosion casts were made at the end of the experimental period. Myocardialvascular anatomy was defined by electron microscopy and capillary abundancederived from this and from the weight of casts from representative areas.Leucocyte deposition was assessed using radioisotope-labelled leucocytes.Ischaemic damage to tissues was graded according to light and electronmicroscopic findings. RESULTS: In Group A the mean (+/- S.D.) vascular castweight/volume of myocardium (density) was 125 +/- 9 mg/mm3. Aftercardioplegic arrest (Group B), it fell to 74 +/- 7 mg/mm3 (P < 0.0001)due to absence of capillaries, although arterioles, venules andnon-nutritive bypass vessels remained patent. Following reperfusion withwhole blood (Group C), capillary numbers partially recovered but luminaldiameters were reduced with a cast density of 94 +/- 5 mg/mm3 (P