Successful combined minimally invasive direct coronary artery bypass and transapical aortic valve implantation

Transapical aortic valve implantation is indicated in high-risk patients with aortic stenosis and peripheral vascular disease requiring aortic valve replacement. Minimally invasive direct coronary artery bypass grafting is also a valid, minimally invasive option for myocardial revascularization in patients with critical stenosis on the anterior descending coronary artery. Both procedures are performed through a left minithoracotomy, without cardiopulmonary bypass, aortic cross-clamping, and cardioplegic arrest. We describe a successful combined transapical aortic valve implantation and minimally invasive direct coronary bypass in a high-risk patient with left anterior descending coronary artery occlusion and severe aortic valve stenosis.     

Long-term survival rates after prolonged aortic cross-clamping with St. Thomas' Hospital cardioplegia

Prolonged aortic cross-clamping (in excess of 120 min) was necessary in 154 cardiac surgical patients. St. Thomas' Hospital cardioplegia was used for myocardial preservation. Quantitative polarization microscopy enabling quantitative birefringence measurements to assess the change in birefringence of the muscle fibres in response to the addition of buffer containing ATP and calcium (i.e. myocardial contractility) was used to detect whether there had been any deterioration in right or left ventricular myocardium during the bypass period. 30 day survival was 90%, long-term (60 months) survival was 80%. In single valve replacements, patients with aortic valvular replacement had 100% survival up to 92 months, whereas patients with mitral valvular replacement had survival rates of 83% after 12 months and 27% after 60 months. Survival rates after 60 months were 89% for coronary artery bypass grafting, 80% for multiple valve replacements, and 74% for combined valvular and coronary artery bypass grafting surgery. Quantitative birefringence assessment of function showed that in the surviving patients 5% had functional deterioration during bypass whereas in the non-surviving patients 70% had functional deterioration. It may be concluded that after cardiac surgery necessitating prolonged aortic cross-clamping--once the initial operative problems are overcome--reasonable long-term results can be obtained by using St. Thomas' Hospital cardioplegia.     

Clinical study on the use of retrograde cardioplegia with St. Thomas' Hospital solution

One hundred and three consecutive patients with aortic valve disease and twenty seven patients with ischemic heart disease of severe critical coronary stenosis or left main trunk stenosis underwent open heart operations with the use of retrograde cardioplegic technique for myocardial protection. Under complete cardiopulmonary bypass, a balloon catheter was inserted into the coronary sinus through small right atriotomy and secured in place. Retrograde cardioplegia was accomplished using cold St. Thomas' Hospital solution by drip method at height of 60 to 80 cm with topical saline slush. Cardiac resuscitation was very easy and acceptable hemodynamics were obtained in all patients. Even in 8 patients in which aortic crossclamping time was above 180 minutes cardiac recovery was excellent except one who needed IABP support. Eight patients in aortotomy group were died postoperatively from the reasons unrelated to myocardial protection. Postoperative hemodynamic data and enzymatic analyses of CK-MB revealed good myocardial protective effects. Retrograde cardioplegia with the use of cold St. Thomas' Hospital solution is thus an effective alternative of myocardial protection in aortic valve surgery or aortotomy surgery and in coronary revascularization for multiple coronary stenoses or left main trunk lesions.     

Reperfusion with nifedipine: improved functional recovery after cold cardioplegic arrest

Nifedipine, an antagonist of myocardial calcium uptake, given after a period of a cold, cardioplegic arrest (150 min, 18 degrees C, St Thomas' cardioplegic solution) improved contractile recovery of the isolated working rat heart model of cardiopulmonary bypass. The hearts were reperfused with various concentrations of nifedipine in Krebs-Henseleit buffer (37 degrees C, 100 cm H2O) and their functional recoveries were compared with the control series reperfused without nifedipine. A bell-shaped dose/response curve was produced by the drug, and optimal protection observed with 0.1 mumol/l of nifedipine which improved the post-ischaemic recovery of the aortic flow from 56.8% +/- 3.7% to 80.1% +/- 3.2% (P less than 0.001). The importance of careful dose adjustment is stressed since it was noted that higher concentrations inhibit both functional and metabolic performance. This study supports the hypothesis that at the end of a cold cardioplegic arrest there are still reversibly injured cells which could restore their function if the cellular ingress of Ca++ during reperfusion is reduced by nifedipine.     

Ultrastructural study comparing the efficacy of five different methods of intraoperative myocardial protection in the human heart

The quality of myocardial protection during cardiac arrest in cardiac operations was investigated in 310 patients. Eighty patients underwent aortic valve replacement and 230 had coronary artery bypass grafting. Four different cardioplegic solutions (Kirsch, Bretschneider, St. Thomas' Hospital, and Hamburg) and the method of induced fibrillation were tested by ultrastructural analysis of the degree of ischemic injury at the end of the cardiac arrest period. Hypothermia was identical in all five groups. In this study, subendocardial and subepicardial needle biopsies were evaluated by a standardized scoring system. Chemical cardioplegia produced mainly moderate ultrastructural injury independent of the time of ischemia. Kirsch cardioplegia and the intermittent fibrillation procedure produced ischemic injury of greater and unpredictable severity. Only with Kirsch cardioplegia was a correlation observed between the duration of intraoperative arrest and the degree of injury, which is indicative of a lack of myocardial protection. The tolerance to ischemia was significantly better in patients undergoing bypass grafting than in those with aortic valve disease and therefore longstanding hypertrophy. In conclusion, the Bretschneider, St. Thomas' Hospital, and Hamburg solutions provide satisfactory myocardial protection but are not able to completely prevent myocardial ischemic injury. Kirsch cardioplegia and the intermittent fibrillation procedure provide insufficient myocardial protection. Patients with left ventricular hypertrophy are at a greater risk during cardiac operations than patients undergoing coronary bypass operations.     

Mechanisms of myocardial protection by adenosine-supplemented cardioplegic solution: myofilament and metabolic responses

OBJECTIVE: Adenosine supplementation of cardioplegic solutions in cardiac operations improves postarrest myocardial recovery after cardioplegic arrest and reperfusion; however, the mechanism of the action of adenosine remains unknown. We tested the hypotheses that adenosine-supplemented cardioplegic solution improves myofibrillar protein cooperative interaction and increases myocardial anaerobic glycolysis. METHODS: The hearts of male Sprague-Dawley rats were randomized to undergo 120 minutes of cardioplegic arrest with 1 of 3 cardioplegic solutions: (1) St Thomas' Hospital No. 2 cardioplegic solution (St Thomas group), (2) St Thomas' Hospital No. 2 cardioplegic solution plus adenosine (100 micromol/L) (adenosine group), and (3) St Thomas' Hospital No. 2 cardioplegic solution plus adenosine (100 micromol/L) plus the nonspecific adenosine receptor antagonist 8-p -sulfophenyltheophylline (50 micromol/L) (sulfophenyltheophylline group). A fourth group of hearts underwent no cardioplegic arrest. RESULTS: Systolic and diastolic functional recovery was improved in the adenosine group compared with that in the other two groups, independent of coronary flow. Adenosine supplementation of cardioplegic solution prevented the decrease in myofibrillar protein cooperative interaction seen after cardioplegic arrest and reperfusion (St Thomas and sulfophenyltheophylline groups). Adenosine-supplemented cardioplegic solution also caused significantly increased anaerobic glycolysis during cardioplegic arrest. These responses were blocked in the sulfophenyltheophylline group. CONCLUSIONS: The changes in myocardial glycolytic activity and myofilament cooperativity coincided with functional recovery in the three cardioplegia groups and may represent mechanisms underlying protection with adenosine-supplemented cardioplegic solution.     

On-pump beating heart mitral valve surgery without cross-clamping the aorta

BACKGROUND AND AIM: Cardiac reperfusion injury is a well-described complication occurring after ischemia or following cardioplegic arrest. Various strategies have been developed to prevent ischemic reperfusion injury. The aim of this study was to assess the efficacy and applicability of the on-pump beating heart mitral valve surgery without cross-clamping the aorta in order to prevent reperfusion injury. METHODS: The prospective study (between April 2005 and December 2006) included 88 consecutive patients who underwent mitral valve surgery. The operations were carried out on a beating heart using normothermic cardiopulmonary bypass without cross-clamping the aorta, therefore perfusing the heart antegradely through the aortic root. Venting the heart from the aorta and the pulmonary vein provided adequate visualization of the operative field. RESULTS: Seventy-eight patients (88.6%) underwent mitral valve replacement and 10 patients (11.3%) underwent mitral valve repair with this technique. Concomitant surgery was required in 29 patients (32.9%). Twenty-five patients (28.4%) had also undergone previous open heart surgery. Mean cardiopulmonary bypass time was 57.4 +/- 18.4 minutes. Mean duration of ventilation was 12.2 +/- 3.5 hours, mean intensive care unit stay was 1.3 +/- 1.6 days, and mean hospital stay was 6.9 +/- 4.5 days. One-year survival was 96.6% for all causes of mortality. CONCLUSIONS: In this study, we showed that on-pump beating heart operations without cross-clamping is an acceptable surgical choice for mitral valve disease. Complication rates are low and perioperative mortality is lower than that generally reported with conventional technique.     

The optimal oxygenation of cardioplegic solution--the buffer effect of carbon dioxide and pH control

A series of studies was undertaken to establish the optimal oxygenation of St. Thomas' Hospital cardioplegic solution (ST). Using an isolated working rat heart model of cardiopulmonary bypass and the cardioplegic arrest the effect of oxygenation of ST were investigated in this study. The effects of oxygenated ST with various O2/CO2 mixture (100% O2, 99% O2 + 1% CO2, 98% O2 + 2% CO2, 95% O2 + 5% CO2) upon post ischemic functional recovery were compared with those of non-oxygenated ST. Under both normothermic and hypothermic conditions, the pH of the St. Thomas' gassed with 99% O2 + 1% CO2 mixture was maintained at 7.8, and this cardioplegic solution showed highest percent recovery of aortic flow. On the contrary, the pH of St. Thomas' cardioplegic solution oxygenated with 100% O2 exceed 9.0 and it showed lethal effect upon postischemic cardiac function. Thus oxygenation of NaHCO3 containing crystalloid cardioplegic solution oxygenated with 100% O2 is rather harmful and the 99% O2 + 1% CO2 gas is the crucial gas mixture for clinical and experimental use with oxygenated ST.     

Changes in whole blood ionized magnesium concentration during cardiac surgery employing St. Thomas' cardioplegic solution

BACKGROUND: Although there is growing evidence to suggest that magnesium supplementation to patients undergoing cardiac surgery is beneficial, the way to administer magnesium is not established. Moreover in Japan St Thomas' cardioplegic solution, containing a high level of magnesium is widely used and the effect of such magnesium-rich cardioplegic solutions on blood magnesium concentration has not been well defined. METHODS: We measured ionized magnesium concentrations (iMg) during cardiac surgery employing St Thomas' solution. Patients were divided into four groups. Group 1 patients were adults and group 2 were children, both of whom received St. Thomas' solution. Group 3 patients underwent cardiopulmonary bypass but did not receive any cardioplegic solution. Group 4 patients underwent off-pump coronary artery bypass grafting. RESULTS: In cardioplegia group (group 1 and 2) iMg was higher than the normal reference range at periods of rewarming, immediately postbypass, and at the end of the operation. iMg at immediately postbypass was related to the total amount of cardioplegic solution. In non-cardioplegia group (group 3 and 4) progressive decrease of iMg was observed throughout the operation. CONCLUSION: Because magnesium in cardioplegic solutions has substantial effect on perioperative iMg, it is crucial to measure iMg to avoid overdose of magnesium when magnesium-rich cardioplegic solutions are employed.     

St. Thomas' Hospital cardioplegic solution. Beneficial effect of glucose and multidose reinfusions of cardioplegic solution

The intention of this study was to determine whether glucose is beneficial in a cardioplegic solution when the end products of metabolism produced during the ischemic period are intermittently removed. The experimental model used was the isolated working rat heart, with a 3-hour hypothermic 10 degrees C cardioplegic arrest period. Cardioplegic solutions tested were the St. Thomas' Hospital No. 2 and a modified Krebs-Henseleit cardioplegic solution. Glucose (11 mmol/L) was beneficial when multidose cardioplegia was administered every 30 minutes. Including glucose in Krebs-Henseleit cardioplegic solution improved postischemic recovery of aortic output from 57.0% +/- 1.8% to 65.8% +/- 2.2%; p less than 0.025. The addition of glucose to St. Thomas' Hospital No. 2 cardioplegic solution improved aortic output from 74.6% +/- 1.9% to 87.4% +/- 1.9%; p less than 0.005. Furthermore, a dose-response curve showed that a glucose concentration of 20 mmol/L gave no better recovery than 0 mmol/L, and glucose in St. Thomas Hospital No. 2 cardioplegic solution was beneficial only in the range of 7 to 11 mmol/L. In addition, we showed that multidose cardioplegia was beneficial independent of glucose. Multidose St. Thomas' Hospital No. 2 cardioplegia, as opposed to single-dose cardioplegia, improved aortic output recovery from 57.4% +/- 5.2% to 74.6% +/- 1.9%; p less than 0.025, and with St. Thomas' Hospital No. 2 cardioplegic solution plus glucose (11 mmol/L) aortic output recovery improved from 65.9% +/- 2.9% to 87.4% +/- 1.9%; p less than 0.005. Hence, at least in this screening model, the St. Thomas' Hospital cardioplegic solution should contain glucose in the range of 7 mmol/L to 11 mmol/L, provided multidose cardioplegia is given. We cautiously suggest extrapolation to the human heart, on the basis of supporting clinical arguments that appear general enough to apply to both rat and human metabolisms.     

Superior protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium. Clinical study in comparison with St. Thomas' Hospital solution

The protective effect of low-calcium, magnesium-free potassium cardioplegic solution on ischemic myocardium has been assessed in adult patients undergoing heart operations. Postreperfusion recovery of cardiac function and electrical activity was evaluated in 34 patients; 16 received low-calcium, magnesium-free potassium cardioplegic solution (group I) and 18 received St. Thomas' Hospital solution, which is enriched with calcium and magnesium (group II). There were no significant differences between the two groups in age, sex, body weight, and New York Heart Association functional class. Aortic occlusion time (107.3 +/- 46.8 minutes versus 113.6 +/- 44.3 minutes), highest myocardial temperature during elective global ischemia (11.5 degrees C +/- 3.1 degrees C versus 9.3 degrees C +/- 3.2 degrees C), and total volume of cardioplegic solution (44.2 +/- 20.5 ml/kg versus 43.4 +/- 17.6 ml/kg) were also similar in the two groups. On reperfusion, electrical defibrillation was required in four cases (25.5%) in group I and in 15 cases (83.3%) in group II (p less than 0.005), and bradyarrhythmias were significantly more prevalent in group II (6.3% versus 44.4%; p less than 0.05). Serum creatine kinase MB activity at 15 minutes of reperfusion (12.3 +/- 17.0 IU/L versus 42.6 +/- 46.1 IU/L; p less than 0.05) and the dose of dopamine or dobutamine required during the early phase of reperfusion (1.8 +/- 2.5 micrograms/kg/min versus 6.1 +/- 3.3 micrograms/kg/min; p less than 0.0002) were both significantly greater in group II. Postischemic left ventricular function, as assessed by percent recovery of the left ventricular end-systolic pressure-volume relationship in patients who underwent aortic valve replacement alone, was significantly better in group I (160.4% +/- 45.5% versus 47.8% +/- 12.9%; p less than 0.05). Serum level of calcium and magnesium ions was significantly lower in group I. Thus low-calcium, magnesium-free potassium cardioplegic solution provided excellent protection of the ischemic heart, whereas St. Thomas' Hospital solution with calcium and magnesium enabled relatively poor functional and electrical recovery of the heart during the early reperfusion period. These results might be related to differing levels of extracellular calcium and magnesium on reperfusion.     

A clinical comparative study between crystalloid and blood-based St Thomas' hospital cardioplegic solution.

OBJECTIVE: Myocardial protection with blood cardioplegia during cardiac surgery is increasingly preferred, but few studies have compared the protective effects of crystalloid cardioplegia to the same solution with blood as the only variable. This clinical study compared the protective effects of crystalloid or blood-based St. Thomas' Hospital cardioplegic solution No. 1. METHODS: Fifty higher risk patients undergoing elective coronary artery bypass surgery, with an ejection fraction less than 40%, were randomly allocated to receive cold (4 degrees C) intermittent crystalloid St. Thomas' No. 1 cardioplegia (n = 25), or a similar blood-based solution (n = 25) with a haematocrit of 10-12%. We determined (1) peri-operative and post-operative arrhythmias, (2) left and right ventricular function (24 h) using the thermodilution technique, (3) left ventricular high-energy phosphate content sampled before ischaemia, the end of ischaemia and the end of bypass. RESULTS: Pre-operative haemodynamic data, aortic cross-clamp and bypass times were similar in both groups of patients; there was no mortality. At the end of ischaemia there were no differences in ATP content between groups but creatine phosphate was maintained at a significantly (P < 0.007) higher level in the blood-based St. Thomas' cardioplegia group than the crystalloid St. Thomas' cardioplegia group (20+/-2 (SE) vs. 13+/-1 micromol/g dry wt, respectively). Return to spontaneous sinus rhythm was significantly (P = 0.002) increased in the blood-based St. Thomas' cardioplegia group (96%) compared to the crystalloid St. Thomas' cardioplegia group (60%). Early post-operative ventricular dysfunction occurred in both groups, but normal LV function (stroke work index) recovered significantly (P = 0.043) more rapidly (by 2 h) in the blood-based St. Thomas' cardioplegia group of patients. CONCLUSIONS: In a higher risk (EF < 40%) group of patients undergoing elective cardiac surgery, addition of blood to an established crystalloid cardioplegic solution significantly enhanced myocardial protection by reducing arrhythmias, improving rate of recovery of function and maintaining myocardial high-energy phosphate content during ischaemia.     

Long-term preservation of explanted hearts perfused with L-aspartate-enriched cardioplegic solution. Improved function, metabolism, and ultrastructure.

The effects of supplementing oxygenated St. Thomas' Hospital cardioplegic solution No. 2 with L-aspartate and/or D-glucose for the long-term preservation of excised rat hearts were determined with isolated working heart preparations. Left ventricular function was assessed at 37 degrees C with a crystalloid perfusate, before cardioplegic arrest and after 20 hours of low-flow perfusion (1.5 ml/min) with continuing arrest at 4 degrees C, and after this period, again at 37 degrees C with a crystalloid perfusate. Four groups (n = 8/group) of hearts were studied with four cardioplegic solutions: St. Thomas' Hospital solution alone, St. Thomas' Hospital solution with aspartate 20 mmol/L, St. Thomas' Hospital solution with glucose 20 mmol/L, and St. Thomas' Hospital solution plus both aspartate and glucose (20 mmol/L each). The addition of glucose to St. Thomas' Hospital solution made no significant difference in the recovery of aortic flow rates (17.7% +/- 8.6% and 21.6% +/- 7.8% of prearrest values), but when aspartate or aspartate and glucose were present, hearts showed significant improvements (89.8% +/- 5.2% and 85.0% +/- 6.2%, respectively). These improvements were associated with a reduction in the decline of myocardial high-energy phosphates during reperfusion, a reduction in cellular uptake of Na+ and Ca++, and a reduction in ultrastructural damage. These results indicate that low-flow perfusion with St. Thomas' Hospital solution plus aspartate can considerably extend the duration of safe storage of explanted hearts.     

Pretreatment with aminophylline reduces release of Troponin I and neutrophil activation in the myocardium of patients undergoing cardioplegic arrest.

OBJECTIVE: Cardioplegic arrest and subsequent reperfusion results in myocardial injury partly related to local inflammation in the heart. It has been proven that aminophylline has numerous anti-inflammatory effects. This study has been designed to evaluate the effects of aminophylline used as a cardioprotective agent for patients undergoing cardiopulmonary bypass (CPB) for valve replacement. METHODS: Thirty patients undergoing elective valve replacement were randomized to receive either aminophylline (n=15), or normal saline (control n=15). Administration of aminophylline (5mg/kg) was injected intravenously after induction of anesthesia. The cardiac Troponin I (cTnI), myocardial myeloperoxidase (MPO) activity, atrial cyclic AMP, and a coronary sinus neutrophil count were measured before and after cardioplegic arrest. RESULTS: There were no differences between the two groups with regard to clinical variables. The cTnI concentration increased significantly after aortic declamping in both groups. However, it was significantly lower, 8h after aortic declamping, in aminophylline group (1.00+/-0.41 vs 2.37+/-1.35 ng/ml p=0.038). The atrial cAMP was significantly higher before aortic cross-clamping in aminophylline group (42.5+/-6.7 pmol/g tissue vs 30.6+/-12.4 pmol/g tissue p=0.04). In addition, we found that the aminophylline group had a significantly lower MPO after reperfusion (1.50+/-0.58 U/g tissue vs 0.86+/-0.24 U/g tissue p=0.003), and a significantly lower neutrophil count 30 min after aortic declamping (0.68+/-0.11x10(3) cell/ml vs 0.32+/-0.16x10(3) cell/ml, p=0.023). CONCLUSIONS: Pretreatment with intravenous aminophylline reduces the subclinical myocardial injury and neutrophil activation in patients undergoing CPB for valve replacement.     

Creatine phosphate: an additive myocardial protective and antiarrhythmic agent in cardioplegia

The potential for enhancing myocardial protection by adding high-energy phosphates to cardioplegic solutions was investigated in a rat heart model of cardiopulmonary bypass and ischemic arrest. Creatine phosphate (CP) was evaluated as an additive to the St. Thomas' Hospital cardioplegic solution. Dose-response studies (CP 0 to 50 mmol/L) revealed 10.0 mmol/L as the optimal concentration which improved recovery of aortic flow and cardiac output after a 40 minute period of normothermic (37 degrees C) ischemic arrest from 21.2% +/- 5.4% and 32.8% +/- 4.6% in the CP-free control group to 82.5% +/- 3.7% and 82.6% +/- 4.2% (p less than 0.001), respectively. Creatine kinase (CK) leakage was reduced by 68.7% (p less than 0.001) in the CP group. With hypothermic (20 degrees C) ischemia (240 minutes) and multidose (every 30 minutes) cardioplegia, recoveries of aortic flow and cardiac output were improved from 33.1% +/- 8.4% and 42.2% +/- 7.7% in the CP-free control group to 77.9% +/- 4.2% and 79.6% +/- 4.3% (p less than 0.001), respectively, in the drug group. In addition to improving function and decreasing CK release, CP reduced reperfusion arrhythmias, significantly decreasing the time between cross-clamp removal and return of regular rhythm and also completely obviating the need for electrical defibrillation. 51Chromium-ethylenediaminetetraacetic acid (51Cr-EDTA), an extracellular space marker, was used to study the disappearance of CP from the cardioplegic solution during its stasis in the heart. Upon reperfusion, two thirds of the infused dose appeared unchanged in the coronary effluent; the remainder was either degraded or accumulated by the myocardium. Despite its alleged inability to enter the myocardial cell, exogenous CP exerts potent protective and antiarrhythmic effects when added to the St. Thomas' Hospital cardioplegic solution. Although the mechanism of action remains to be elucidated, it may involve binding or uptake of the drug.     

Cardiac ischemic preconditioning improves lung preservation in valve replacement operations

BACKGROUND: Previous work has shown that cardiac ischemic preconditioning reduces cardiac reperfusion injury. We investigated whether cardiac ischemic preconditioning can improve lung preservation in patients who undergo valve replacement. METHODS: Forty patients with rheumatic heart disease requiring valve replacement were randomly divided into two groups. Twenty patients received two cycles of 3 minutes of aortic cross-clamping and 2 minutes of reperfusion before cardioplegic arrest (group IP), and 20 patients underwent 10 minutes of cardiopulmonary bypass (group C, control group). Blood samples from the pulmonary vein were collected to measure levels of polymorphonuclear leukocytes, superoxide dismutase, malonedialdehyde, and thromboxane B2, and arterial oxygen tension. Blood samples from the coronary sinus were used to measure calcitonin gene-related peptide values. Hemodynamic data were recorded by a pulmonary artery Swan-Ganz catheter. Lung tissue was collected after 1 hour of reperfusion to evaluate morphology. Clinical outcome data were recorded. RESULTS: In group C (cardiopulmonary bypass and cardioplegic arrest), the levels of polymorphonuclear leukocytes, thromboxane B2, malonedialdehyde, and calcitonin gene-related peptide were increased after 1 hour of reperfusion, whereas the value for superoxide dismutase was decreased. In group IP, preconditioning attenuated the increase in polymorphonuclear leukocytes, thromboxane B2, and malonedialdehyde (p < 0.05) and increased superoxide dismutase and calcitonin gene-related peptide levels (p < 0.05). Preconditioning also increased arterial oxygen tension and cardiac index compared with controls (p < 0.05) and decreased mean pulmonary artery pressure and pulmonary vascular resistance index (p < 0.05). Histologic findings showed less lung injury and a lower polymorphonuclear leukocyte count in group IP than in group C (p < 0.05). Group IP had fewer postoperative pulmonary complications and a shorter intubation time. CONCLUSIONS: Cardiac ischemic preconditioning improves lung preservation in patients having valve replacement. The mechanism may be that cardiac ischemic preconditioning reduces the accumulation of polymorphonuclear leukocytes in lung tissue and decreases the formation of oxygen free radicals.     

Protection of ischemic myocardium by exogenous phosphocreatine. II. Clinical, ultrastructural, and biochemical evaluations

In valve replacement operations on 78 patients with acquired heart disease, the efficiency of phosphocreatine in intraoperative protection of ischemic myocardium was evaluated by clinical, morphologic, and biochemical methods. Phosphocreatine (8 to 10 mmol/L) in a blood cardioplegic solution was used in operations on 41 patients; in the control group (37 patients) standard blood cardioplegia was used. In the group with phosphocreatine treatment we observed more rapid recovery of hemodynamics after release of the aortic cross-clamp, a decreased frequency of fibrillation, and more frequent restoration of sinus rhythm even if there were sinus rhythm disturbances before aortic cross-clamping. Analysis of the biopsy samples taken from the right ventricle showed protection of the sarcolemma against ischemic damage afforded by phosphocreatine and complete preservation of high-energy phosphates. The results obtained confirm the conclusion made by Robinson, Braimbridge, and Hearse (J Thorac Cardiovasc Surg 1984; 87:190-200) that phosphocreatine is an effective additional cardioprotective agent when used in cardioplegic solutions.     

Effect of ischemic postconditioning in adult valve replacement.

OBJECTIVE: Ischemic postconditioning (POC) by brief episodes of ischemia performed just at the time of reperfusion can reduce infarct size in animal models and clinical settings of percutaneous coronary intervention. However, the clinical applicability of postconditioning in cardiac surgery remains to be determined. We investigated the effect of postconditioning on myocardial protection in patients undergoing valve replacement. METHODS: Fifty adult patients scheduled for elective valve replacement under cold blood cardioplegic arrest were randomly assigned to postconditioning (n=25) or control treatment (n=25). Postconditioning was performed by three cycles of 30s ischemia and 30s reperfusion using aortic re-clamping and de-clamping started 30s after cardioplegic arrest. The creatine kinase-MB, troponin I, transcardiac release of lactate were assayed. Measurements of clinical results were recorded during the study. RESULTS: The types of procedure, age, bypass and aortic cross-clamping times were similar in both groups. The postoperative peak creatine kinase-MB was lower after aortic de-clamping in the postconditioning patients compared with the control group (66+/-24 U/l vs 84+/-20 U/l, p=0.02) and peak cTnI was similar in both groups. The required inotropes were reduced in postconditioning group compared with the control group (2.3+/-1.8 vs 4.1+/-2.2 microg/min/kg, p=0.03). There were reduction trends with regard to transcardiac release of lactate in postconditioning group compared with the control group (0.10+/-0.17 mmol/l vs 0.24+/-0.16 mmol/l, p=0.08). The transcardiac neutrophil count during reperfusion was less in POC group compared with the control group (7.8+/-6.3% vs 14.0+/-8.7%, p=0.04). CONCLUSIONS: The present study demonstrated that postconditioning may protect adult myocardium undergoing cold blood cardioplegic arrest. These data support the need for a further clinical trial of postconditioning in cardiac surgery.     

Combining off pump coronary artery bypass with mitral valve replacement

Background Conventional approach to combined coronary artery bypass grafting (CABG) and mitral valve replacement (MVR) is associated with longer cardiopulmonary bypass (CPB) and aortic cross clamp (ACC) time leading to high operative risk. Methods We conducted a retrospective review of nine consecutive patients undergoing coronary artery bypass grafting/mitral valve replacement combining the off pump technique with cardioplegic arrest. Elective intra aortic balloon pump (IABP) support was instituted in all cases. CABG was first done in all cases without cardiopulmonary bypass support. Mitral valve replacement was then done using conventional cardiopulmonary bypass and cardioplegic arrest using the superior septal approach. Results Nine consecutive patients underwent coronary artery bypass grafting with mitral valve replacement including three patients with acute myocardial infarction. Preoperative echocardiogram revealed a mean ejection fraction (EF) of 38.4 ± 6.0%. Intra aortic balloon pump was inserted in all patients preoperatively. The average number of grafts were 3.0 ± 0.7. Eight patients received bioprosthetic valve while one patient received mechanical prosthesis. The average length of stay in intensive care unit was 3.3 ± 0.5 days. There was no mortality. One patient had superficial wound infection. Conclusion The data suggest that the combined technique (off pump coronary artery bypass grafting and conventional mitral valve replacement) is a safe method to perform coronary artery bypass grafting/mitral valve replacement with minimal morbidity and mortality.     

Right ventricular function in retrograde cardioplegia for myocardial protection--an experimental study

Anterior cardiac veins which are the main drainage vessels of the right ventricle drain directly into the right atrium. Therefore, the right ventricular wall may not be perfused effectively during open heart surgery by the use of retrograde cardioplegic method resulting in postoperative right ventricular dysfunction. Seventeen mongrel dogs were subjected to this study and were placed on cardiopulmonary bypass using a conventional heart-lung machine. Total aortic cross-clamping time was 60 minutes in all dogs. In Group I (n = 6), 4 degrees C St. Thomas' Hospital solution (15 ml/kg body weight) was injected into the aortic root by the use of a syringe. Cardioplegic solution was replenished every 20 minutes with a half of the initial dose (7.5 ml/kg body weight). Group II (n = 6) were the dogs with the retrograde cardioplegia in which 4 degrees C St. Thomas' Hospital solution (15 ml/kg body weight) was given retrogradely from the coronary sinus by the drip method at the height of 60 cm, and the replenishing dose and interval of cardioplegia were the same as Group I. Group III (n = 5) was the dogs treated with retrograde cardioplegia identical to Group II and the combined use of topical cooling with ice-slush. The hearts were resuscitated after 60 minutes of aortic cross-clamping. Right ventricular functions such as cardiac output, right atrial pressure, right ventricular end-diastolic pressure, right ventricular max dp/dt, and shortening fraction of the right ventricle were measured 15, 30, 45, and 60 minutes after cardiac resuscitation respectively. In Group II, right atrial pressure was significantly elevated from the control value 15 and 30 minutes after cardiac resuscitation. On the other hand, all indices of right ventricular functions in Group III showed insignificant changes. The present experimental study demonstrated the retrograde cardioplegic method could produce right ventricular perfusion resulting in right ventricular dysfunction early after cardiac resuscitation. This deleterious effect however could be prevented by the combined use of topical cooling of the right ventricle with ice-slush.