Impact of myocardial protection during coronary bypass surgery on patient outcome.

We have recently shown that continuous coronary perfusion with warm blood enriched with the ultra-short acting beta-blocker Esmolol (ES) improves functional and structural myocardial protection during coronary artery surgery as compared with conventional cardioplegia (CP). The purpose of the present study was to compare both myocardial protection techniques in terms of patient outcome. We retrospectively analyzed the charts of 150 consecutive patients subjected to coronary artery surgery using the ES-technique; 150 patients matched for age, gender, preoperative left ventricular function, history of renal failure, and history of neurological symptoms undergoing surgery with conventional CP during the same time period served as control group. There were no significant differences between both groups with respect to perioperative myocardial infarction rate, need for positive inotropic medication, need for mechanical circulatory support, duration of mechanical ventilation, duration of intensive care unit stay, time of mobilization, postoperative renal failure, cardiac arrhythmias, neurological symptoms, infections or in-hospital mortality. ES-patients were less frequently readmitted to the intensive care unit (ES: 3/150; 2.2% [95% confidence interval: 0-4.2%] vs. CP: 13/150; 8.7% [4.2-13.2%]; P=0.010) and total hospital stay was shorter (ES: 12.3+/-4.8 days [95% CI: 11.5-13.0] vs CP: 13.5+/-3.8 [12.9-14.1] days; P=0.0013), thus saving 159 patient days on the normal ward. Procedural costs were less for the ES-technique (US$ 60 per patient) as compared to the cardioplegia technique (US$ 120 per patient). These data suggest that myocardial protection using the ES-technique does not improve clinical outcome in patients subjected to routine coronary artery surgery, but may save costs.

Myocardial beta-blockade as an alternative to cardioplegic arrest during coronary artery surgery.

The authors' recent experimental work has demonstrated that myocardial protection using continuous coronary perfusion with warm beta-blocker-enriched blood avoids myocardial ischaemia and minimizes myocardial oedema formation, thus completely preserving left ventricle function. The purpose of this clinical study was to compare this alternative technique in terms of structural and functional myocardial protection with the routinely used crystalloid Bretschneider cardioplegia. Sixty coronary artery surgery patients were randomized to receive either crystalloid cardioplegia or continuous coronary perfusion with warm blood enriched with the ultra-short acting beta-blocker esmolol. Cardiac function was evaluated using transoesophageal echocardiography (fractional area of contraction) and cardiac metabolism using arterial-coronary sinus lactate concentration difference (a - csD(LAC)). From left ventricular biopsies, the authors determined myocardial oedema, heat-shock-protein-70, intercellular-adhesion-molecule and actin pattern. Patients with crystalloid cardioplegia received 3.6 +/- 0.8 grafts during 64 +/- 20 min cross-clamp time (beta-blocker: 3.5 +/- 0.9 grafts during 68 +/- 22 min; NS). Following cross-clamp removal crystalloid cardioplegia hearts released significant lactate amounts (a- csD(LAC)) - 1.0 +/- 0.6 versus - 0.1 +/- 0.2 mmol/litre in beta-blocker hearts; P < 0.05). In crystalloid cardioplegia hearts, myocardial water content increased from 82.1 +/- 2.1% pre-cardiopulmonary bypass to 83.2 +/- 1.7% at the end of cardiopulmonary bypass (P < 0.05); in beta-blocker hearts myocardial water content remained unchanged (pre-cardiopulmonary bypass: 82.3 +/- 1.9%; end of cardiopulmonary bypass: 82.4 +/- 1.7%; NS). At the end of cardiopulmonary bypass, left ventricular biopsies of beta-blocker hearts showed less structural damage as determined by heat shock protein-70, intercellular adhesion molecule-I and deranged actin cross-striation pattern as compared with crystalloid cardioplegia hearts (P < 0.05). The post-cardiopulmonary bypass fractional area of contraction was similar in both groups (beta-blocker: 65 +/- 14%; crystalloid cardioplegia: 62 +/- 16%); however, beta-blocker patients required less inotropic stimulation (dopamine: beta-blocker: 2.9 +/- 2.5 versus crystalloid cardioplegia: 5.0 +/- 2.3 microg/kg per min; P < 0.05). The data suggest that continuous coronary perfusion with warm esmolol-enriched blood results in better myocardial protection compared with crystalloid cardioplegia. It is concluded that the concept of beta-blocker-induced cardiac surgical conditions may be a useful alternative for myocardial protection during coronary artery surgery.

Excellent recovery after prolonged heart storage by preservation with coronary oxygen persufflation: orthotopic pig heart transplantations after 14-hr storage.

BACKGROUND: Improvement of heart preservation is still the greatest challenge in preservation research. The unchanged severe restriction of acceptable storage periods of heart grafts since the beginning of clinical heart transplantation indicates that technical innovations are necessary if a substantial improvement is to be achieved. METHODS: Here, we present the results of hypothermic preservation using the innovative technique of coronary oxygen persufflation (COP). COP simply adds gaseous oxygen to hypothermic graft storage and requires only a "valve guard" for reversible closure of the aortic valve. Fourteen-hr preservation was followed by orthotopic transplantation and evaluations of functional as well as metabolic recovery. Mature pig hearts, a model with restricted preservation tolerance similar to the human heart, were used to guarantee the clinical relevance of this study. RESULTS: After 14-hr hypothermic storage, COP-preserved hearts were able to recover within 2 hr of cardiopulmonary bypass to a steady cardiovascular function without mechanical or pharmacologic support. The left ventricular pressure amplitude of mHTK-COP-preserved hearts as well as energy charge potential recovered to pregrafting values and the ventricular power output to 66%. Hearts simply stored in University of Wisconsin (UW), modified Bretschneider's histidine-tryptophan-ketoglurate (mHTK), or Euro-Flush with glutathione (EFG) solution had only limited recovery, with significantly lower ventricular power output of 18%, 29% or 30% of pregrafting controls on average. CONCLUSIONS: Fourteen-hr oxygenated pig heart preservation using COP results in optimal recovery. Storage preservation in solutions containing hyaluronidase (mHTK and EFG) results in higher recoveries as compared to UW solution, an effect that may support the excellent recovery after mHTK-COP preservation.

Increasing the colloid osmotic pressure of cardiopulmonary bypass prime and normothermic blood cardioplegia minimizes myocardial oedema and prevents cardiac dysfunction.

UNLABELLED: Our recent work demonstrated that normothermic continuous antegrade blood cardioplegia results in cardiac dysfunction related to myocardial oedema. This oedema was partially due to increased myocardial microvascular fluid filtration induced by crystalloid hemodilution. We hypothesized that increasing the colloid osmotic pressure of blood cardioplegia would stop fluid filtration into the cardiac interstitium, thus preventing myocardial oedema and cardiac dysfunction. METHODS: We determined myocardial water content in six dogs by microgravimetry and myocardial lymph flow from the major prenodal cardiac lymphatic. Preload recruitable stroke work was derived from sonomicrometry and micromanometry. The dogs were subjected to normothermic cardiopulmonary bypass primed with 6% hetastarch and 1 h of normothermic continuous antegrade blood cardioplegia (4:1 blood:6% hetastarch colloid osmotic pressure 21 +/- 2 mmHg) delivered at 50 mmHg perfusion pressure. RESULTS: We found that despite increased colloid osmotic pressure, a small but significant increase in myocardial water content still occurred during blood cardioplegia. As myocardial lymph flow virtually ceased during cardioplegia, myocardial microvascular filtration must have been present. However, increased myocardial lymph flow following cardioplegia resulted in complete oedema resolution associated with normal left ventricular performance post-cardiopulmonary bypass. CONCLUSIONS: Our data show that the plegic myocardium is prone to oedema formation because of both relatively enhanced fluid filtration and lymph flow cessation. We conclude that increasing the colloid osmotic pressure of normothermic blood cardioplegia minimizes myocardial oedema, thus preventing post-cardiopulmonary bypass cardiac dysfunction.

Surgical repair of a large residual atrial septal defect after transcatheter closure.

Transcatheter closure of ostium secundum atrial septal defects is a less invasive method of repairing atrial septal defects in comparison with an open heart operation. In selected patients the transvenous closure of atrial septal defects may be an effective alternative. Defects with circumferential septal rims, secundum atrial defects, and patent foramen are the best candidates for this method. We report a case in which a large residual atrial septal defect after transvenous closure with a Sideris occluder device required surgical closure.

Mitral valve remodeling using autologous pericardium: an experimental study.

The aim of this study was to assess in vivo the efficacy of a new technique for remodeling the mitral valve. In 6 dogs during cardiopulmonary bypass and cardioplegic cardiac arrest, both mitral valve leaflets were totally separated from the mitral ring and resected subtotally, leaving intact their narrow margins with insertion sites of the chordae tendineae of the first and second order. To mimic pathologic conditions, the chordae tendineae were then altered by placing two shortening sutures for every chordal stem. Based on standardized geometric calculations and using autologous pericardium treated with 0.62% glutaraldehyde solution, the new leaflets were then remodeled intraoperatively and sutured in place, merging them with the subvalvular apparatus and the native mitral ring. After restoration of stable circulatory conditions, valve function was evaluated under rest and defined loading conditions using a 5.0-MHz ultrasound transducer, applied epicardially. We found that intraoperative remodeling of the mitral valve leaflets using autologous pericardium with preservation of the subvalvular apparatus is possible and reproducible, and can be performed even when the subvalvular apparatus is altered morphologically. Functionally, the remodeled valve proved to be satisfactory under conditions of rest and stress. The benefits conferred by autologous tissue, the reproducibility of the surgical technique, the good functionality of the remodeled valve, and the preservation of the subvalvular apparatus could make this technique a useful surgical alternative for extensive mitral valve reconstruction procedures in pediatric and adult patients.