Social deprivation and prognostic benefits of cardiac surgery: observational study of 44 902 patients from five hospitals over 10 years.

OBJECTIVE: To assess the effects of social deprivation on survival after cardiac surgery and to examine the influence of potentially modifiable risk factors. DESIGN: Analysis of prospectively collected data. Prognostic models used to examine the additional effect of social deprivation on the end points. SETTING: Birmingham and north west England. PARTICIPANTS: 44 902 adults undergoing cardiac surgery, 1997-2007. MAIN OUTCOME MEASURES: Social deprivation with census based 2001 Carstairs scores. All cause mortality in hospital and at mid-term follow-up. RESULTS: In hospital mortality for all cardiac procedures was 3.25% and mid-term follow-up (median 1887 days; range 1180-2725 days) mortality was 12.4%. Multivariable analysis identified social deprivation as an independent predictor of mid-term mortality (hazard ratio 1.024, 95% confidence interval 1.015 to 1.033; P<0.001). Smoking (P<0.001), body mass index (BMI, P<0.001), and diabetes (P<0.001) were associated with social deprivation. Smoking at time of surgery (1.294, 1.191 to 1.407, P<0.001) and diabetes (1.305, 1.217 to 1.399, P<0.001) were independent predictors of mid-term mortality. The relation between BMI and mid-term mortality was non-linear and risks were higher in the extremes of BMI (P<0.001). Adjustment for smoking, BMI, and diabetes reduced but did not eliminate the effects of social deprivation on mid-term mortality (1.017, 1.007 to 1.026, P<0.001). CONCLUSIONS: Smoking, extremes of BMI, and diabetes, which are potentially modifiable risk factors associated with social deprivation, are responsible for a significant reduction in survival after surgery, but even after adjustment for these variables social deprivation remains a significant independent predictor of increased risk of mortality.

Logistic, additive or historical: is EuroSCORE an appropriate model for comparing individual surgeons' performance?

Both versions of the EuroSCORE, the complex logistic and the simpler additive, have been used for comparing institutional performance, but they are no longer robust enough to be used for comparing individual surgeons. It is now time to tighten the standard and add additional data to obtain a more holistic picture of the quality of cardiac surgical care in the UK.

Reduced adipocyte insulin sensitivity in Caucasian and Asian subjects with coronary heart disease.

The association between insulin resistance and coronary heart disease (CHD) is strong in the British Indian-Asian population. Adipocyte metabolism may contribute to both insulin resistance and CHD. We examined insulin-stimulated glucose uptake in adipocytes and in vivo insulin sensitivity using the fasting insulin resistance index (FIRI) in 60 subjects (45 Caucasian and 15 Asian) with CHD and 30 Caucasian subjects without CHD. In 25 CHD subjects (18 Caucasian and 7 Asian), the relationship between adipocyte insulin sensitivity and non-esterified fatty acid (NEFA) suppression to oral glucose was examined. Compared with controls, the CHD subjects had higher values of fasting insulin [51 (46 to 54) pmol l(-1) vs 36 (31 to 41) pmol l(-1) p< 0.01] and FIRI [1.65 (1.5 to 1.79) vs 1.06 (0.89 to 1.23), p < 0.01]. Among the CHD subjects, the Asians had higher values than Caucasian [insulin 58 (48 to 67) pmol l(-1) vs 48 (44 to 53) pmol l(-1) p < 0.01, FIRI 1.89 (1.44 to 2.13) vs 1.62 (1.4 to 1.79), p< 0.01)]. Insulin-stimulated glucose uptake in adipocytes was lower in the CHD than control subjects [56 (50 to 62) vs 115 (75 to 132) attomol min(-1).mm2, p < 0.05], being most reduced among the Asians. It was positively correlated with postprandial NEFA suppression and negatively with insulin release. In conclusion, abnormalities of adipocyte function and insulin sensitivity occur in CHD and may contribute to its aetiology.

Coronary revascularization in the treatment of moderate and severe postischemic left ventricular dysfunction.

Chronic postischemic left ventricular (LV) dysfunction can improve following coronary revascularization (hibernating myocardium). However, it is not clear whether the severity of LV dysfunction determines functional outcome after revascularization and the accuracy of tests to predict myocardial viability. We studied 47 patients with coronary artery disease and chronic LV dysfunction. Before coronary bypass, patients underwent (18F)2-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) during euglycemic hyperinsulinemic clamp to assess viability. Global and regional LV function were assessed before and 4 to 6 months after surgery. Patients were arbitrarily divided into 2 groups with moderate and severe LV dysfunction. Group 1 (n = 26) had an ejection fraction (EF) of < or = 30% and group 2 (n = 21) > 30%. After bypass, the EF (22+/-6% vs 31+/-10%; p <0.0001) and global wall motion score (WMS) (2.05+/-0.39 vs 1.56+/-0.34; p <0.001) improved in group 1, whereas the EF (43+/-9% vs 43+/-12%; p = NS) was unchanged in group 2, although WMS tended to improve (1.42+/-0.38 vs 1.32+/-0.39; p = 0.09). The proportion of dysfunctional segments (72% vs 32%; p <0.0001) and FDG uptake in these segments (0.44+/-0.15 vs 0.34+/-0.15 micromol/g/min, p <0.0001) were greater in group 1 than in group 2. The baseline EF influenced the predictive accuracy of PET, with highest positive predictive accuracy in group 2 and highest negative predictive accuracy in group 1. Thus, coronary revascularization has the potential for greatest benefit in patients with the most severe dysfunction, but with evidence of viability, and the entity of LV dysfunction affects the predictive accuracy of viability studies.

Effect of cardiopulmonary bypass perfusion protocols on gut tissue oxygenation and blood flow.

BACKGROUND: Previous studies in patients undergoing cardiopulmonary bypass (CPB) have documented gastric mucosal hypoperfusion and hypoxia. This study examines the influence of the CPB protocol on the adequacy of gut blood flow and oxygenation. METHODS: Twenty-four patients were prospectively randomized into one of four CPB groups: nonpulsatile hypothermic (NP 28); pulsatile hypothermic (P 28); non-pulsatile normothermic (NP 37); and pulsatile normothermic (P 37). Gastric wall blood flow was assessed using laser Doppler flow measurement and gastric mucosal oxygenation (intramucosal pH), using tonometry. RESULTS: After 10 minutes of CPB, the NP 28 group had the greatest reduction in gastric wall blood flow (-60.6% +/- 3.8%) compared with baseline (p < 0.05). Thirty minutes into CPB, the P 37 group had less gastric mucosal hypoperfusion (-9.7% +/- 10.3%) than the NP 28 patients (-53.0% +/- 8.6%; p < 0.05). All groups showed a hyperemic response immediately after CPB. No significant differences between the four groups were found for gastric mucosal oxygenation during or after CPB. A progressive decline occurred in this variable during the period 3 to 4 hours after CPB. At this time, total-body oxygen consumption and extraction were at their maximum. CONCLUSIONS: This study found that perfusion protocol can influence mucosal blood flow, but other overriding factors that operate during and after CPB act to cause mucosal hypoxia. These findings, particularly the timing of mucosal hypoxia, may have implications for centers contemplating early extubation or "fast tracking" of patients after CPB.

Pathophysiology of chronic left ventricular dysfunction. New insights from the measurement of absolute myocardial blood flow and glucose utilization.

BACKGROUND: Chronically dysfunctional myocardium may improve after coronary revascularization. This condition was thought to be due to a chronically reduced myocardial blood flow (MBF). Recently, however, it has been shown that in patients without previous infarction but with chronic left ventricular dysfunction, baseline MBF was normal. METHODS AND RESULTS: To study the pathophysiology of chronic left ventricular dysfunction in patients with previous infarction, regional MBF (milliliter per minute per gram of water-perfusable tissue) and glucose utilization (MRG; micromoles per minute per gram) during hyperinsulinemic euglycemic clamp were measured with positron emission tomography in 30 patients before bypass. At baseline, 133 myocardial segments were normal, and 107 were dysfunctional. After revascularization, 59 of 107 segments improved, while 48 of 107 were unchanged. MBF was 0.92 +/- 0.25 mL.min-1.g-1 in normal segments, 0.87 +/- 0.31 mL.min-1.g-1 in improved segments (P = NS versus normal), and 0.82 +/- 0.40 mL.min-1.g-1 in unchanged segments (P < .05 versus normal). In 90% of the dysfunctional segments, MBF was > 0.42 mL.min-1.g-1, a cutoff value corresponding to the mean MBF minus 2 SD in normal segments. The MRG was 0.71 +/- 0.14 mumol.min-1.g-1 in 9 age-matched normal subjects, 0.45 +/- 0.19 mumol.min-1.g-1 (P < .01) in normal segments, 0.44 +/- 0.14 mumol.min-1.g-1 in improved segments (P = NS versus normal), and 0.34 +/- 0.17 mumol.min-1.g-1 in unchanged segments (P < .01 versus normal and improved). CONCLUSIONS: The results suggest that resting MBF measured with 15O-labeled water in chronically dysfunctional segments is not reduced and that the myocardium of these patients is less sensitive to insulin than that of normal subjects.

Angiography and the aetiology of heart failure.

The diagnosis of idiopathic dilated cardiomyopathy should not be made without first performing a coronary angiogram. If the cause of heart failure is unknown this should be stated rather than attributing the cause to dilated cardiomyopathy. Severe ventricular dysfunction may improve dramatically after revascularisation in some cases of coronary disease. Preservation of R waves on the surface electrocardiogram suggests the presence of hibernating myocardium but thallium scintigraphy or positron emission tomography scanning should be employed to investigate this further.

Endotoxaemia detected during cardiopulmonary bypass with a modified Limulus amoebocyte lysate assay.

Cardiopulmonary bypass (CPB) is associated with blood heparin level fluctuations and a reduction in haematocrit due to crystalloid haemodilution. The effect of these changes on the reliability of the Limulus amoebocyte lysate (LAL) chromogenic microassay for the measurement of plasma endotoxin was assessed in vitro. It was shown that the assay could be significantly compromised by twofold haemodilution which can occur during CPB. The interference effect on the assay caused by CPB-associated heparin was not significant if a comparatively large amount of heparin (25 IU/ml) was added to the blood at the time of sampling. The effect of haemodilution was counteracted by prediluting plasma samples with crystalloid by a factor dependent on the sample haematocrit (to ensure that the proportion of plasma was similar in all samples). A correction was then required to determine the endotoxin level in the original sample. The modified assay was used to determine sequential plasma endotoxin levels in 14 patients undergoing hypothermic nonpulsatile CPB. Endotoxaemia occurred at the time of aortic cross-clamp release and reached a peak of 48.9 +/- 12.9 ng/l shortly before the end of CPB, which was significantly higher than baseline values pre-CPB (p < 0.05). Thereafter, there was a decline in endotoxin levels to 28.9 +/- 13.6 ng/l 24 hours later which was still significantly higher than baseline levels (p < 0.05). Peak endotoxaemia was a predictor of protracted hospital stay when compared with haemodynamic and tissue perfusion parameters.

Assessment of the value of the immediate postoperative chest radiograph after cardiac operation.

The value of the immediate postoperative chest radiograph upon a patient's return to the intensive care unit after a cardiac surgical procedure is uncertain. This study represents a prospective analysis of the immediate postoperative radiograph in 100 consecutive adult patients undergoing cardiac operations. In 11 patients it was found that the routine postoperative radiograph was of value when it was necessary either to clarify or confirm clinical findings or to check the position of an intraaortic balloon catheter. For those chest radiographs that were deemed unnecessary, only one of 89 were found to be of clinical value. Furthermore, in those situations in which an emergency radiograph was obtained, the routine radiograph was not found to be contributory to patient management. We conclude that the policy of obtaining routine, immediate postoperative chest radiographs in the absence of a specific clinical indication provides virtually no additional clinical yield. Residents should therefore request radiographs only to check the position of an intraaortic balloon catheter, and to clarify or confirm a clinical diagnosis.

Carcinoid heart disease: early failure of an allograft valve replacement.

A woman who had carcinoid syndrome and carcinoid heart disease underwent tricuspid and pulmonary valve replacements with a xenograft and a cryopreserved allograft, respectively. Within 3 months of the operation severe pulmonary regurgitation and pulmonary hypertension refractory to medical therapy developed. Autopsy found the biomechanical tricuspid valve to be free of disease but the allograft in the pulmonary position was involved by carcinoid heart disease in a fashion similar to the excised native pulmonary valve.

Co-expression of renin-angiotensin system component genes in human atrial tissue.

OBJECTIVES: To detect co-expression of genes coding for components of the renin-angiotensin system and investigate the potential for variation in the level of angiotensin converting enzyme (ACE) gene expression in the right atrial appendage of patients undergoing heart surgery. DESIGN: The right atrial appendage was collected at the time of surgery from 30 randomly chosen patients and was rapidly frozen in liquid nitrogen prior to extraction of messenger (m)RNA. Surgical samples of heart valve (n = 6) and papillary muscle (n = 3) were also examined. METHODS: Aliquots of purified mRNA were reverse-transcribed for analysis of gene expression by a polymerase chain reaction amplification assay. Primers specific for angiotensinogen, renin, ACE, cardiac chymase, atrial natriuretic peptide, glyceraldehyde-3-phosphate dehydrogenase, adenosine deaminase and the transferrin receptor were used for a qualitative analysis of co-expression of these genes within the same sample. In a subgroup of eight patients, a quantitative comparison of the relative levels of ACE gene expression was performed using a competitive polymerase chain reaction. RESULTS: Angiotensinogen and ACE expression were detected in all atrial, valve and ventricular samples examined, at levels similar to those of 'housekeeping' genes such as the transferrin receptor. Atrial renin and chymase expression were more difficult to detect, being demonstrable in only 70 and 63% of the samples, respectively. Higher levels of chymase were detected in ventricular samples than in atrial tissues. A quantitative analysis of ACE expression in eight atrial samples provided evidence of interindividual variation in the relative level of atrial ACE expression. CONCLUSIONS: The essential components of the renin-angiotensin system are co-expressed at a low level in the right atrial appendage and are detectable in other regions of the human heart. Renin and chymase genes are expressed at a lower level than the angiotensinogen and ACE genes and exhibit regional differences in expression. Interindividual variation in the relative level of ACE expression can be detected by a competitive polymerase chain reaction.

Effects of cardiopulmonary bypass on gut blood flow, oxygen utilization, and intramucosal pH.

Studies documenting rises in endotoxin after cardiopulmonary bypass (CPB) have postulated gut mucosal hypoperfusion. We have investigated alterations in jejunal blood flow by laser Doppler flow measurement, intramucosal pH (pHi) by tonometry, and oxygen utilization in a canine model of hypothermic CPB (n = 11 dogs). After 10 minutes of hypothermic CPB, despite no major reduction in superior mesenteric artery flow, mucosal laser Doppler flow decreased to -38.2% +/- 9.3% of levels obtained before bypass (p = 0.008) and serosal laser Doppler flow, to -47.3% +/- 11.4% (p = 0.006). During the hypothermic phase, mesenteric oxygen consumption fell from 0.18 +/- 0.01 to 0.098 +/- 0.01 mL.min-1.kg-1 (p = 0.005), and mesenteric oxygen delivery fell from 1.97 +/- 0.39 to 1.14 +/- 0.12 mL.min-1.kg-1 (p = 0.05). There was no change in jejunal pHi. During the rewarming phase, there was a substantial increase in mucosal laser Doppler flow, peaking at +69.8% +/- 15.2% (p = 0.03), whereas serosal laser Doppler flow returned to values seen prior to CPB (-16.4% +/- 21.5%; p = 0.25). These changes coincided with a surge in oxygen consumption (0.33 +/- 0.042 mL.min-1.kg-1; p = 0.009), while mesenteric oxygen delivery remained depressed at 1.09 +/- 0.12 mL.min-1.kg-1 (p = 0.04). Jejunal pHi fell from a value of 7.36 +/- 0.04 before CPB to 7.12 +/- 0.07 (p = 0.02), thus indicating mucosal hypoxia. During the rewarming phase of hypothermic CPB, there is a disparity between mesenteric oxygen consumption and oxygen delivery with villus tip ischemia; these findings may explain the pathophysiology of endotoxemia during CPB.

The effect of cardiopulmonary bypass on gastric and colonic mucosal perfusion: a tonometric assessment.

In a study to assess the potential effect of nonpulsatile hypothermic cardiopulmonary bypass (CPB), intramucosal pH (pHi) of the gastric and colonic mucosae was determined by tonometry (n = 8). During the hypothermic phase of CPB, gastric and colonic pHi did not change significantly. Forty minutes after the start of rewarming, despite increases in the cardiac index and mean arterial blood pressure, gastric pHi fell from 7.53 +/- 0.02 to 7.31 +/- 0.03 (p = 0.017) and colonic pHi fell from 7.50 +/- 0.02 to 7.32 +/- 0.03 (p = 0.028). Forty minutes after the end of CPB both the colonic (p = 0.017) and gastric (p = 0.046) pHi remained depressed below pre-CPB values. The difference in the arterial (pHa) and the gastric mucosal pH changed from -0.097 before CPB to 0.016, 40 minutes after the end of CPB (p = 0.027). This alteration in the pHa-pHi underlines the importance of measuring intramucosal pH by tonometry, since the pHa and pHi may move in opposite directions during episodes of haemodynamic stress. Both the gastric and colonic pHi were found to have a linear correlation with the pHa, although changes in the gastric pHi (r = 0.41, p = 0.018) were more strongly correlated with the pHa than the colonic pHi (r = 0.23, p = 0.19) in the rewarming phase of CPB and the immediate post-CPB period when there was a tendency towards intramucosal acidosis. The development of intramucosal acidosis in the rewarming and immediate post-CPB phases following hypothermic nonpulsatile CPB may impair the gut barrier and predispose patients to the absorption of luminal toxins.