Systemic pulmonary shunts in neonates: early clinical outcome and choice of surgical approach.

BACKGROUND: Systemic pulmonary shunt remains a major strategy for the palliation of cyanotic lesions in neonates despite the associated morbidity and mortality. METHODS: Between March 1993 and December 1998, 79 systemic pulmonary shunts were performed in 75 neonates with cyanosis and severely reduced pulmonary blood flow. The mean age was 11.5 days and the mean weight, 3 kg. All neonates were dependent on duct flow and prostaglandin E1 infusion for adequate oxygenation. RESULTS: The systemic pulmonary shunt was performed through a right thoracotomy in 36 patients, left thoracotomy in 6, and median sternotomy in 33 patients. The 30-day mortality was 3 patients (4%). Univariate and logistic regression analyses revealed a weight less than 2 kg (p = 0.039) and preoperative mechanical ventilation (p = 0.008), to be predictors of early mortality, whereas pulmonary hypoplasia (p = 0.55), diagnostic group (p = 0.79), shunt size (p = 0.2), and surgical approach (p = 0.5) were not. There were seven episodes of shunt-related complications that required early intervention. CONCLUSIONS: Systemic pulmonary shunt remains an effective palliative measure in cyanotic neonates despite specific complications. Both low weight and preoperative ventilation represent significant risk factors for early mortality.

Congenital division of the left atrium: the influence of associated congenital lesions on the timing and mode of presentation.

PURPOSE OF STUDY: Congenital division of an atrium is commonly associated with other cardiac malformations, which may influence presentation. BASIC METHODS: Cases diagnosed at our institution between 1980 and 1997 were reviewed, to determine whether associated lesions influence presentation. PRINCIPLE FINDINGS: 52 patients were diagnosed with atrial division (49 left, 3 right), mean age 4.8 yr. Patients could be divided according to age at diagnosis. Group 1: 32 patients aged < or = 1 yr. 14 patients had associated cardiac malformations other than atrial septal defect (ASD). Presentation was with pulmonary oedema. Group 2: 20 patients > 1 yr. 5 patients had associated major malformations other than ASD. Commonest presentation--isolated shortness of breath. Fifty patients underwent membrane resection and correction of associated anomalies (4% mortality). At follow-up (mean 12 yr) all patients were in NYHA class I or II. CONCLUSIONS: Patients with division of the atrium present early in infancy and with more severe symptoms when associated with other cardiac malformations.

Surgical management of transposition of great arteries associated with multiple ventricular septal defects.

OBJECTIVE: The presence of associated multiple ventricular septal defects (VSDs) increases the risk of the anatomic repair for transposition of the great arteries (TGA). The aim of this study was to define the optimal management of this complex anomaly. METHODS: Between January 1988 and December 1998, 45 patients underwent anatomic repair of TGA associated with multiple VSDs. The median age was 50 days and the median weight 4 kg. Eighteen (40%) had undergone previous palliation including 17 pulmonary artery banding procedure (PAB), seven associated with coarctation repair and one isolated coarctation repair. The perimembraneous septum was involved in 24 patients, the trabecular in 43, the inlet in seven and the infundibular in two. Closure of the VSDs included Dacron or pericardial patchs and matress sutures. The initial approach was through right atriotomy which was sufficient in 15 patients. VSDs were closed through right ventriculotomy in 13 patients, through pulmonary artery in six, through the aorta in one and in the remaining (n = 10) combined approaches were used. Only one patient required left apical ventriculotomy. RESULTS: There were five hospital deaths (11%; 70% CL: 6-18%) including the one early reoperation for residual VSD closure. Five patients had successful early reoperation for secondary PAB for residual VSD. Three late deaths occurred (7%; 70% CL: 3-13%). At the last visit, 95% of survivors were asymptomatic and without any cardiac medication. CONCLUSION: Mid-term survival with good quality of life can be achieved following either one or two-stage repair of this complex anomaly. In the presence of VSD closure failure a secondary PAB may be the procedure of choice.

Ascites and weight loss in a child: due to congenital division of the right atrium.

Congenital division of an atrial chamber is a very rare congenital malformation that more commonly affects the left atrium but which may, in rare circumstances, involve the right atrium. Such a divided right atrium may present with symptoms consistent with increased portal venous pressure. Reported is a case with unusual clinical presentation. The patient underwent resection of the dividing shelf with good postoperative results.

Ischaemic preconditioning reduces troponin T release in patients undergoing coronary artery bypass surgery.

OBJECTIVE: To investigate whether ischaemic preconditioning could reduce myocardial injury, as manifest by troponin T release, in patients undergoing elective coronary artery bypass surgery. DESIGN: Randomised controlled trial. SETTING: Cardiothoracic unit of a tertiary care centre. PATIENTS: Patients with three vessel coronary artery disease and stable angina admitted for first time elective coronary artery bypass surgery were invited to take part in the study; 33 patients were randomised into control or preconditioning groups. INTERVENTION: Patients in the preconditioning group were exposed to two additional three minute periods of myocardial ischaemia at the beginning of the revascularisation operation, before the ischaemic period used for the first coronary artery bypass graft distal anastomosis. MAIN OUTCOME MEASURE: Serum troponin T concentration at 72 hours after cardiopulmonary bypass. RESULTS: The troponin T assays were performed by blinded observers at a different hospital. All patients had undetectable serum troponin T (< 0.1 microgram/l) before cardiopulmonary bypass, and troponin T was raised postoperatively in all patients. At 72 hours, serum troponin T was lower (P = 0.05) in the preconditioned group (median 0.3 microgram/l) than in the control group (median 1.4 micrograms/l). CONCLUSIONS: The direct application of a preconditioning stimulus in clinical practice has been shown, for the first time, to protect patients against irreversible myocyte injury.

Preconditioning the human heart.

The phenomenon of ischaemic preconditioning protects the myocardium by limiting infarct size in animal models of ischaemia and reperfusion. Ischaemic preconditioning may be induced by short periods of ischaemia and reperfusion. We investigated whether the human heart can be ischaemically preconditioned during coronary artery bypass grafting (CABG). Patients were enrolled into two separate studies. In the first study myocardial adenosine triphosphate (ATP) was used as the measured endpoint, assayed from myocardial biopsies taken at onset of cardiopulmonary bypass (CPB), at the end of the preconditioning stimulus, and at the end of a 10 min sustained ischaemic insult. In the second study the release of myocardial troponin T was used as the endpoint; taken at pre-CPB, and at 1, 6, 24, and 72 h after CPB. In both studies, patients were randomised into either the preconditioning group or the control group. Preconditioning was induced, after the onset of CPB, with two 3 min periods of crossclamping and an intervening 2 min of reperfusion, followed by 10 min sustained ischaemia. The control group only received 10 min of sustained ischaemia. Ischaemic preconditioning resulted in a slower rate of ATP (mumol/g dry weight) depletion in the preconditioned hearts at the end of the 10 min of sustained ischaemia (preconditioned: 11.5 +/- 0.8 vs control: 7.2 +/- 0.3; P < 0.005). Also, preconditioning resulted in a slower rate of troponin T release which was significantly different at 72 h after CPB in the preconditioned group (0.3 milligram) when compared with the control group (1.4 milligrams; P < 0.05). In addition, more patients in the preconditioned group had troponin T levels lower than 0.5 milligram at 72 h than in the control group (10 vs 3 patients). Both groups of patients received the same number of grafts, and underwent the same length of ischaemia during the procedure. We conclude that in patients undergoing CABG surgery, ischaemic preconditioning may reduce myocardial injury as shown by the favourable changes in myocardial ATP, and serum troponin T levels.

The incidence of significant pericardial effusion and tamponade following major aortic root surgery.

OBJECTIVE: To examine the hypothesis that the incidence of significant pericardial effusion following aortic root surgery is higher than anticipated after cardiac surgery. DESIGN: A retrospective data analysis. SETTING: A tertiary referral centre for cardiothoracic surgery. SUBJECTS: All patients undergoing aortic root surgery either with or without aortic valve replacement between January 1991 and July 1993. RESULTS: Three patients developed late cardiac tamponade (7-10 days post-operatively) and a further three developed clinically significant pericardial effusions as a result of post-pericardiotomy syndrome. The 31.6% (95% confidence limit: 12.5-56%) incidence of significant pericardial effusions following aortic root surgery is therefore significantly higher than anticipated after cardiac surgery (0.8-6). CONCLUSION: These data support the hypothesis that the incidence of significant pericardial effusion following aortic root surgery is higher than anticipated after cardiac surgery. We recommend that echocardiography is routinely performed during the post-operative period in these patients to exclude significant pericardial effusions.

Ischaemic preconditioning and cardiac surgery.

OBJECTIVE: This review discusses the phenomenon of ischaemic preconditioning and its potential application to cardiac surgery. The biology of ischaemic preconditioning is explained and the more limited evidence suggesting that the human heart can be preconditioned is discussed. METHODS AND RESULTS: It is now accepted that the heart is capable of short-term rapid adaptation in response to brief ischaemia so that during a subsequent, more severe ischaemic insult myocardial necrosis is delayed-ischaemic preconditioning. The infarct-delaying properties of ischaemic preconditioning have been observed in all species studied. Five minutes of ischaemia is enough to initiate preconditioning and the protective period lasts for 1-2 h. Laboratory experiments have demonstrated that the stimulation of adenosine receptors initiates preconditioning and the intracellular signal transduction mechanisms involve protein kinase C and ATP-dependent potassium channels, although there may be some differences between species. An analysis of studies on myocardial infarction in humans has revealed that some patients reporting angina in the days before infarction have a better outcome and this may be due to the ischaemia causing preconditioning. More direct evidence has come from an investigation of patients undergoing percutaneous transluminal angioplasty in whom the ST-segment changes induced by balloon inflation were more marked during the first inflation than the second. In patients undergoing coronary artery bypass grafting the decline in ATP content during the first 10 min of ischaemia was reduced in patients subjected to a brief preconditioning protocol. CONCLUSIONS: Preconditioning is a powerful and reproducible method of protecting the myocardium from irreversible ischaemic injury. There is now evidence indicating that the human heart can be preconditioned. However, more trials are necessary in patients undergoing cardiac surgery before the role of preconditioning as a means of myocardial protection can be assessed.

Coronary artery fistulas presenting with bacterial endocarditis.

Coronary artery fistulas are rare congenital malformations. Two cases presenting with bacterial endocarditis are described. Both were treated successfully by grafting of the coronary artery and ligation of the fistula.

Recurrent left atrial myxoma.

Based on statistics from the UK, the incidence of myxoma is about 1:1,000,000/year. Three recent cases of recurrent myxoma are reported, one where excision was probably incomplete, one where tumour implantation may have occurred and one where a mesenchymal sarcoma was misinterpreted histologically. The relative importance of these three factors in recurrence of cardiac tumours after surgical excision is discussed.

Preconditioning the human heart during aorto-coronary bypass surgery.

UNLABELLED: Ischaemic preconditioning, with brief periods of ischaemia separated by reperfusion, increases myocardial resistance to infarction. In addition, preconditioning leads to preservation of myocardial adenosine triphosphate (ATP) during ischaemia. We propose that ischaemic preconditioning may share fundamental similarities with intermittent aortic cross-clamping utilised during aorto-coronary bypass surgery. The aim of this study was to test the hypothesis that controlled aortic cross-clamping is a form of preconditioning using conservation of ATP as the end point. Patients randomised to the preconditioned group (preconditioned, n = 10 patients), received a preconditioning stimulus of two 3-min periods of cross-clamping separated by 2 min of reperfusion prior to an ischaemic insult of 10 min ischaemia and ventricular fibrillation. In the control group (control, n = 10 patients) hearts received 10 min cross-clamping with fibrillation without prior preconditioning. Myocardial ATP, creatine phosphate (CP), and lactate were determined from biopsy specimens taken at the onset of cardiopulmonary bypass (A), at the end of preconditioning (B), and at the end of 10 min of ischaemic insult (C). RESULTS: expressed as mean +/- SE (mumol/g dry weight). Preconditioning resulted in a significant depletion of the myocardial ATP content (preconditioned, B: 11.7 +/- 0.9 vs A: 19.8 +/- 1.4; P < 0.01). Furthermore 10 min of ischaemia resulted in a significant depletion of ATP in the control patients (control, C: 7.2 +/- 0.3 vs B: 19.5 +/- 1.2; P < 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of the time period between preconditioning ischemia and prolonged ischemia on myocardial protection.

Ischemic preconditioning with brief periods of ischemia followed by reperfusion protects the myocardium against a subsequent prolonged ischemic insult. Reperfusion may influence the protection given by ischemic preconditioning by washing out metabolites that are accumulated during the preconditioning ischemia. This study was designed to define the duration of reperfusion necessary to provide such protection. Hearts of anesthetized rats were preconditioned by occlusion of the left coronary artery for 5 minutes. This was followed by reperfusion for either 1 minute (n = 6) or 30 seconds (n = 6). The hearts were then subjected to a sustained occlusion of the left coronary artery for 45 minutes followed by reperfusion for 3 hours. Control (n = 11) hearts were subjected only to occlusion of the left coronary artery for 45 minutes followed by reperfusion for 3 hours. Infarct size was measured using tetrazolium and expressed as a percentage of the region at risk. After reperfusion for 1 minute there was a significant reduction in the size of the infarct (32.3 +/- 4.1%), expressed as a percentage of the zone at risk, when compared to controls (61.9 +/- 3.5%) (p < 0.01). However, the protection received by preconditioning was lost when reperfusion was limited to 30 seconds (infarct size 63.4 +/- 3.2%). The results show that the minimum period of reperfusion required to give protection after preconditioning ischemia lies between 30 seconds and 1 minute.