Long-term event-free survival with an embolised prosthetic valve leaflet in the thoracic aorta.

We report the case of a patient who underwent a redo surgery for a leaflet escape from a Bjork-Shiley tilting disc mitral prosthesis inserted 18 years previously. The escaped disc remained lodged in the thoracic aorta without any complication. She ultimately died of terminal heart failure 13 years after the second operation. We believe this to be the longest survival with a dislodged leaflet from a mechanical valve. Removal of dislodged disc is recommended in literature but there may be a place for watchful observation in exceptional cases with no haemodynamic compromise.

Alteration in transthoracic impedance following cardiac surgery.

INTRODUCTION: Haemodynamically significant ventricular tachyarrhythmias are a frequent complication in the immediate post-operative period after cardiac surgery. Successful cardioversion depends on delivery of sufficient current, which in turn is dependent on transthoracic impedance (TTI). However, it is uncertain if there is a change in TTI immediately following cardiac surgery using cardiopulmonary bypass (CPB). METHODS: TTI was measured on 40 patients undergoing first time isolated cardiac surgery using CPB. TTI was recorded at 30 kHz using Bodystat Multiscan 5000 equipment before operation (with and without a positive end-expiratory pressure (PEEP) of 5 cm of H(2)O) and then at 1, 4 and 24 h after the operation. Data was analyzed to determine the relationship between pre- and post-operative variables and TTI values. RESULTS: Mean pre-operative TTI was 54.5+/-10.55 ohms without PEEP and 61.8+/-15.4 ohms on a PEEP of 5 cm of H(2)O. TTI dropped significantly (p<0.001) after the operation to 47.2+/-10.6 ohms at 1 h, 42.6+/-10.2 ohms at 4 h and 41.8+/-10.4 ohms at 24 h. A positive correlation was noted between duration of operation and TTI change at 1 h (r=0.38; p=0.016). There was no significant correlation between the duration of bypass and change in TTI. CONCLUSION: TTI decreases by more than 30% in the immediate post-operative period following cardiac surgery. This state may favour defibrillation at lower energy levels.

Cardiac compression following cardiac surgery due to unrecognised hiatus hernia.

A 76-year-old man who had undergone a routine coronary artery bypass grafting operation developed severe haemodynamic instability in the early postoperative period in spite of multiple inotropic supports. Due to persistent instability of haemodynamics and worsening acidosis his chest was re-explored with detection of no obvious abnormality. An intra-aortic balloon pump (IABP) was inserted for additional support. The chest had to be left open overnight and closed formally next morning. A chest X-ray at that stage showed a large hiatus hernia with huge gastric dilatation compressing the heart. Decompressions of the stomach lead to dramatic improvement in his circulatory status with rapid weaning of inotropes and IABP and he could be extubated. This case illustrates the importance of recognising the presence of hiatus hernia in preoperative chest X-ray and prophylactic NG tube insertion at the time of cardiac surgery in these cases.

Three-dimensional echocardiography is superior to multiplane transoesophageal echo in the assessment of regurgitant mitral valve morphology.

AIMS: Transoesophageal echocardiography (TOE) plays a vital role in the assessment of mitral valve morphology. However, the accuracy of TOE may be limited by inadequate recognition of all segments. We aimed to evaluate the role of three-dimensional (3D) echocardiography in this respect. METHODS AND RESULTS: Seventy-five patients were studied prior to mitral valve repair surgery. A scoring protocol was devised for recognition of the eight Carpentier segments (0=inadequate for analysis, 1=adequate, 2=good). Using surgical findings as the gold standard, TOE and 3D were compared for adequate recognition scores and accurate detection of functional morphology. Adequate recognition was more frequently obtained with 3D imaging (97% of segments by 3D c.f. 90% by TOE; p = 0.000). The major difference was seen at the commissures (adequate scores in 143/150 commissures by 3D c.f. 90/150 by TOE; p = 0.000). 3D matched more closely to surgical findings, achieving exact functional description in 92% of segments vs 79% segments with TOE (p = 0.000). This incremental value of 3D was seen in both commissures and the anterior leaflet but not in the posterior leaflet. CONCLUSIONS: In this study 3D was superior not only for complete recognition of the mitral valve but also for the accurate localisation and identification of pathology.

Dopamine therapy for patients at risk of renal dysfunction following cardiac surgery: science or fiction?

OBJECTIVES: We aimed to evaluate the renoprotective role of renal-dose dopamine on cardiac surgical patients at high risk of postoperative renal dysfunction. The latter included older patients or those with pre-existing renal disease, elevated preoperative serum creatinine (Cr), poor ventricular function, hypertension, diabetes mellitus and unstable angina requiring intravenous therapy. METHODS: Fifty patients undergoing cardiopulmonary bypass (CPB) who fulfilled the entry criteria were prospectively randomized into two groups: Group 1 received a 'renal-dose' (3 microg kg(-1) min(-1)) dopamine infusion starting at anaesthetic induction for 48 h whilst saline infusion acted as placebo in Group 2. The anaesthetic and CPB regimes were standardized. Urinary excretion of retinol binding protein (RBP) indexed to Cr, an accurate and sensitive marker of early renal tubular damage, was assessed daily for 6 days. Additional outcome measures included daily fluid balance, blood urea and serum Cr. Statistical comparisons were made using ANOVA and Mann-Whitney U-test. RESULTS: No significant difference was found between the groups in their age, gender, preoperative NYHA class, ejection fraction, baseline serum Cr and duration of CPB and aortic cross-clamping. Renal replacement therapy was not required in any instance. Both groups demonstrated a similar and significant rise in urinary RBP throughout the study period. Dopamine-treated patients achieved more negative average fluid balance than those on placebo (5 vs. 229 ml, P<0.05). CONCLUSIONS: Renal-dose dopamine therapy failed to offer additional renoprotection to patients considered at increased risk of renal dysfunction after CPB.

Avoiding ischemia in latissimus dorsi muscle grafts: electrical prestimulation versus vascular delay.

BACKGROUND: Surgical mobilization of the latissimus dorsi muscle produces regional ischemic damage that may compromise its function in clinical applications such as cardiomyoplasty. We compared the effectiveness of two procedures designed to maintain blood flow throughout the mobilized muscle. METHODS: Adult pigs were assigned to two experimental groups: an electrically prestimulated group (n = 10) and a vascular delay group (n = 10). In the prestimulated group the left latissimus dorsi muscle was activated in situ at 2 Hz for 24 h/d. In the vascular delay group, the intercostal perforating arteries to the left latissimus dorsi muscle were divided. Two weeks later, hyperemic blood flow was measured by means of fluorescent microspheres immediately before and after mobilizing the latissimus dorsi muscle and again after recovery for a further 2 days. RESULTS: In the prestimulated group, blood flow was not significantly depressed in any region of the muscle immediately after mobilization, and blood flow increased significantly in proximal (p = 0.01), middle (p = 0.02), and distal (p = 0.007) regions following recovery. In muscles subjected to vascular delay the proximal and middle regions showed no significant changes in blood flow after mobilization or recovery, but flow in the distal region was 50% lower after mobilization (p = 0.003), and it remained significantly depressed even after recovery (p = 0.008). CONCLUSIONS: Prestimulation was significantly more effective than vascular delay in preserving distal blood flow. Because it is also less invasive and initiates metabolic transformation before mobilization, this technique should allow cardiac assistance to be introduced at an earlier postoperative stage without compromising the viability of the grafted muscle.

Improved viability of latissimus dorsi muscle grafts after electrical prestimulation.

Surgical mobilization of the latissimus dorsi muscle (LDM) produces fiber degeneration, particularly in the distal part of the graft, that may compromise its function in clinical applications such as dynamic cardiomyoplasty. In five rats, the left LDM was stimulated continuously at 10 HZ. After 5 weeks, vessels perforating the chest wall were divided and the left LDM was mobilized as a pedicle graft based on the thoracodorsal artery. Twenty-four hours later, animals were killed and left and right LDMs were incubated with the vital stain nitroblue tetrazolium. Five control rats underwent a similar procedure without prestimulation. Mobilization of the LDM resulted in a loss of viability in the distal third of the muscle graft. This was reduced significantly by prestimulation (P = 0.006). Blood flow to the distal LDM graft is known to be augmented by electrical stimulation in situ before mobilization; the present results show that there is an associated enhancement of viability. The clinical implications of this finding are discussed.