Non-invasive measurement of peripheral venous oxygen saturation using a new venous oximetry method: evaluation during bypass in heart surgery.

Monitoring of mixed venous oxygen saturation (SvO(2)) is currently performed using invasive fibre-optic catheters. This procedure is not without risk as complications may arise from catheterization. This paper describes an alternative, non-invasive method of monitoring peripheral venous oxygen saturation (SxvO(2)) which, although it cannot replace pulmonary artery catheters, can serve as an adjunct/early warning indicator of when there is an imbalance in oxygen supply and demand. The technique requires the generation of an artificial venous pulse at the finger, thereby causing modulation of the venous blood volume within the digit. The blood volume changes are monitored using an optical sensor. Just as pulse oximetry utilizes the natural arterial pulse to perform a spectrophotometric analysis of the peripheral blood in order to estimate the arterial blood oxygen saturation, the proposed venous oximetry technique uses the artificially generated venous pulse to estimate SxvO(2). A prototype device was tested in a pilot study with patients undergoing heart surgery. Data from this study support the notion that the method is capable of tracking haemodynamic changes and suggests the technique is worthy of further development and evaluation.

Relationship between reduced elasticity of extracardiac vessels and left main stem coronary artery disease.

OBJECTIVES: To investigate the elastic properties of medium-size extracardiac arteries and veins between patients with and without left main stem coronary artery disease. METHODS: The compliance, distensibility, and incremental elastic modulus (iEmod) of the internal thoracic arteries (n=53), long saphenous veins (n=38), and radial arteries (n=35) from 74 patients undergoing coronary surgery were studied in organ baths. Twenty-four patients had left main stem (LMS) disease and 50 non-LMS coronary disease. RESULTS: Internal thoracic arteries from patients with LMS presented significantly lower compliance (-17%) and distensibility (-18%) and significantly higher iEmod (19%) than internal thoracic arteries from patients with non-LMS disease. Radial arteries from patients with LMS presented higher iEmod (50%) than radial arteries from patients with non-LMS disease. Furthermore, long saphenous veins from patients with LMS had reduced compliance (-45%), reduced distensibility (-40%) and increased iEmod (34%) compared to those from patients with non-LMS disease. CONCLUSIONS: LMS coronary disease is associated with a significantly reduced elasticity of extracardiac arteries and veins compared to non-LMS coronary disease. This finding suggests that widespread vascular elasticity defects may play a role in the development of LMS disease and be responsible for the higher incidence of early and late cardiovascular morbidity observed in this condition.

Assessment of the left ventricular diastolic reserve in essential hypertension: the acute saline load test.

OBJECTIVE: The aim of this study was to evaluate the significance of the development of a restrictive response to an acute saline load, defined as an increase in the ratio of peak early to peak late diastolic transmitral flow velocity (E/A ratio) associated with a decrease in the deceleration time, in patients with mild to moderate untreated hypertension. BACKGROUND: Recognised abnormal patterns of transmitral diastolic flow include, from 'best' to 'worst': prolonged relaxation, pseudonormalisation, and restrictive physiology. The common denominator of these transitions is the constellation of an increase in the E/A ratio associated with a decrease in deceleration time. PATIENTS AND METHODS: Sixteen normal control subjects (6 males, 10 females, age 51.6 +/- 6.9 years) and 24 patients with mild to moderate untreated hypertension (12 males, 12 females, age 46.8 +/- 7.5 years) underwent supine blood pressure measurement with sphygmomanometry, biochemical studies, and transthoracic M-mode, 2D, and Doppler echocardiography before and after an acute saline load (7 mL kg(-1), maximum 500 mL, NaCl 0.9% within 15 min IV). RESULTS: The baseline E/A ratio was lower (0.90 +/- 0.14 vs. 1.04 +/- 0.18; P < 0.01) and the deceleration time was longer (158.8 +/- 19.4 vs. 135 +/- 8.9 ms; P < 0.01) in patients with hypertension compared with normotensive controls. However, no patient with hypertension exhibited a transmitral flow velocity pattern compatible with typical prolonged relaxation. A restrictive response to the acute saline load was observed in 12 (50%) of the hypertensive and none of the control subjects. Hypertensive patients with a restrictive response to the acute saline load had a lower baseline E velocity (54.8 +/- 8.7 cm s(-1) vs. 66 +/- 6.4 cm s(-1); P = 0.003), a lower baseline E/A ratio (0.83 +/- 0.13 vs. 0.97 +/- 0.12; P = 0.015), and a longer deceleration time (167.5 +/- 15.4 ms vs. 150 +/- 19.5; P = 0.03) than hypertensive patients without such a response. CONCLUSION: A restrictive response to an acute saline load is indicative of a limited diastolic reserve in patients with mild to moderate untreated hypertension. Further studies are required in order to evaluate the significance of such a response with regards to risk stratification and efficacy of medical treatment in this patient population.

Postoperative stroke in cardiac surgery is related to the location and extent of atherosclerotic disease in the ascending aorta.

OBJECTIVES: The aim of the study was to evaluate the risk from calcified atheromas in the ascending aorta, and the extent and topography of the disease in the development of stroke after cardiac surgery. BACKGROUND: Postoperative stroke constitutes a serious problem in cardiac surgery, and atherosclerosis of the ascending aorta is an important risk factor. METHODS: Before surgical manipulation epiaortic echocardiographic ultrasound was performed to evaluate the ascending aorta in 921 consecutive patients undergoing cardiac surgery. The presence of calcification, location of atheroma, extent of the disease and clinical variables including postoperative stroke were recorded prospectively. RESULTS: A total of 26.2% of the patients had atherosclerosis of the ascending aorta, and in 44.4% of them more than one of 12 possible segments was involved. Logistic regression showed that atherosclerotic disease in the ascending aorta was the most important predictive factor for postoperative stroke. The incidence of stroke was 1.8% in patients without atherosclerotic disease of the ascending aorta, and 8.7% in patients with the disease (p < 0.0001). Diabetes mellitus was also a predictive factor (p = 0.04). A new and unique finding of this study was that the middle-lateral segment is an independent predictive factor for postoperative stroke, with a relative risk of 26% (p = 0.04). CONCLUSIONS: Patients with atheromatosis in the ascending aorta had an 8.7% incidence of postoperative stroke, in spite of minor surgical modifications. The risk depended on the presence, location and extent of the disease. Randomized trials evaluating alternative surgical strategies in coronary surgery are urgently needed in high risk patients.

Successful management of Brucella mellitensis endocarditis with combined medical and surgical approach.

OBJECTIVES: Brucella endocarditis is an underdiagnosed complication of human brucellosis, associated with high morbidity and mortality. We report the successful management of a number of cases of Brucella mellitensis endocarditis. PATIENTS AND METHODS: Seven consecutive cases of Brucella mellitensis endocarditis were treated over the last 20 years, based on high suspicion of the disease at first place. The early suspicion of Brucella endocarditis relied on medical history and a standard tube agglutination titer > or =20. Blood and/or cardiac tissue cultures were positive in all patients, but available late following surgery. All patients were successfully treated with a combination of aggressive medical and early surgical therapy. All affected valves were replaced within 1 week from admission (five aortic and three mitrals). Medical treatment included co-trimoxazole, tetracyclines and streptomycin, before surgery, followed by co-trimoxazole and tetracyclines for a median of 12 months (range: 3-15 months) after surgery until the titers returned to a level < or =1:160. RESULTS: There were neither operative deaths nor recurrence of infection. One patient died two years after the operation due to massive cerebrovascular accident. Ten-year survival was 85.7+/-13.2%. CONCLUSION: Although Brucella mellitensis endocarditis is a rare entity, its optimum management should be a combination of aggressive medical treatment and early surgical intervention, based on high degree of suspicion in areas with high incidence of the disease.

Transaortic approach for the Alfieri stitch.

The management of associated mitral regurgitation in patients undergoing cardiac surgery is controversial. A simple, reliable, and fast repair is advantageous, especially in critically ill patients. We describe a simple method of transaortic edge-to-edge repair in patients with associated mitral regurgitation undergoing aortic valve surgery.

Stent treatment for coarctation of the aorta: intermediate term follow up and technical considerations.

OBJECTIVE: To report the initial and intermediate term results of stent implantation in children with coarctation of the aorta. PATIENTS AND DESIGN: 17 patients with coarctation of the aorta underwent stent implantation (median age 11 years, range 0.4-15 years); six were treated for isolated coarctation, nine for recurrent coarctation (five after surgical repair and four after balloon dilatation), and two for complex long segment coarctation. INTERVENTIONS: The procedure was guided by a second catheter placed transseptally in the left ventricle or the aorta proximal to the coarctation site, for angiographic and haemodynamic monitoring during the procedure. Twenty two stents were implanted in 17 patients. One of the patients with long segment coarctation received four stents and the other three. Palmaz 4014 stents were placed in 11 patients, Palmaz 308 in five, and Palmaz 154 in one. RESULTS: Immediately after stent implantation the peak systolic gradient (mean (SD)) fell from 50.0 (24.5) to 2.1 (2.4) mm Hg (p < 0.05). The diameter of the stenotic lesion increased from 5.1 (1.5) mm to 13.9 (2.4) mm (p < 0.05). There were no deaths or procedure related complications. At a median follow up of 33 months, no cases of recoarctation were identified, either clinically (0/17; 0%, 95% confidence interval (CI) 0% to 19%) or angiographically (0/13; 0%, 95% CI 0% to 25%). CONCLUSIONS: Stent implantation for the treatment of coarctation of the aorta appears to have very low morbidity and mortality, and reasonable intermediate term results. Long term freedom from recoarctation using this method remains to be determined in comparison with simple balloon dilatation.

The effect of a 'fast-track' unit on the performance of a cardiothoracic department.

OBJECTIVE: The objective of this study was to describe the impact of a 'fast-track' unit, combined with a computerised system for information collection and analysis, on the clinical practice and finance of a cardiothoracic department over the first 12 month period of its application. METHODS: Within 12 months, starting December 1996, 642 major cardiothoracic cases were performed at the Cardiothoracic Department, St Mary's Hospital, London, after the establishment of a 3-bed 'fast-track' unit, which was supported by a computerised system for admission planning and a pre-admission clinic. The main outcome measures were operating numbers, financial income, patient recovery and operative mortality. RESULTS: The 'fast-track' unit resulted in an increase of the operating numbers (11.3% increase in major cardiac cases) and income (38%), as compared with the year before. Some 525 patients out of 642 (81.8%) were scheduled for the 'fast-track' unit and 492 (93.7%) were successfully 'fast-tracked'. Coronary artery bypass grafting operations had the lowest 'fast-track' failure and mortality rates. Re-do operations and complex coronary procedures presented a high 'fast-track' failure rate of approximately 20-25%. Low cardiac output, postoperative bleeding and respiratory problems were the most frequent causes for 'fast-track' failure. CONCLUSIONS: The development of a 'fast-track' unit, supported by a computerised system for information collection and analysis and a pre-admission clinic, has resulted in a substantial improvement of operating numbers and financial income, without adversely affecting the clinical results. This task demanded close collaboration between a dedicated list manager and a designated member of the medical team. Patient selection with appropriate 'fast-track,' criteria may improve further the efficiency of 'fast-track' units in the future.

Technical adjuncts in beating heart surgery comparison of MIDCAB to off-pump sternotomy: a meta-analysis.

OBJECTIVES: The technical aspects of minimal invasive surgery are discussed, together with a comparison of off-pump MIDCAB with off-pump sternotomy, with special respect to outcomes of death, infarct and anastomoses. METHODS: Technical aspects of beating heart surgery are described under the headings: Trauma; Access; Stabilisation; Ischaemia; Haemostasis; Suturing; and Circulatory support. Data from papers and meetings on minimal invasive surgery were collated to September 1998 and correlated with the unit of origin. Percentage figures were back calculated to provide an actual number from which a new data base was obtained relevant to the reporting incidence. For statistical analysis a Chi squared test with Yates correction was used. RESULTS: Sixty-three centres reported 3304 cases of MIDCAB surgery (M) and 21 centres reported over 3060 cases of off-pump surgery through a sternotomy (S). There was no difference in early or late death rates between the two groups (1.6% M:2.2% S). There was a higher infarct rate with MIDCAB (2.9% M: 1.45% S; P < 0.03). The occlusion and stenosis rates for MIDCAB were 3.9 and 6.6% whilst for sternotomy off-pump they were 4.9 and 1.4%. The stenosis difference was significant at the P < 0.001 level. A combined occlusion and stenosis rate showed a higher incidence with MIDCAB (10.5%), than sternotomy 6.4% (P < 0.08). Four major series showed comparative data before and after stabiliser usage in MIDCABs. The stenosis rate was significantly reduced with stabilisation from 9.6 to 3.7% (P < 0.002) as was the combined occlusion and stenosis rate from 16 to 5.0% (P < 0.0001). In the total series there was no significant difference in length of stay (4.6 days), incidence of atrial fibrillation (9%), or between conversion to sternotomy(MIDCAB group) or to bypass (sternotomy group) (5%) between the two groups (M and S). Grafting the right coronary artery by MIDCAB produced worse results than for the left anterior descending artery (LAD). CONCLUSIONS: There is an important failure rate with beating heart surgery; stabilisers reduce this risk and are essential tools in both MIDCAB and beating heart surgery and encourages the further use of minimally invasive approaches.

Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy.

BACKGROUND: Left atrial systolic dysfunction, unexplained by altered loading conditions, has been reported in idiopathic dilated cardiomyopathy suggesting left atrial involvement in the myopathic process. MATERIALS AND METHODS: Seventeen patients with idiopathic dilated cardiomyopathy, 16 with ischemic dilated cardiomyopathy and 18 normal controls were studied with transthoracic echocardiography and cardiac catheterization. Transmitral diastolic flow was evaluated with pulsed Doppler. Left atrial volume (cm3/m2) at mitral valve opening (maximal, Vmax.), onset of atrial systole (P wave of the electrocardiogram, Vp), and mitral valve closure (minimal, Vmin. ) was determined with two-dimensional echocardiography using the biplane area-length method. The left atrial active emptying fraction (ACTEF = [Vp-Vmin.] x 100/Vp) served as an index of systolic function. RESULTS: The peak early diastolic transmitral flow velocity (cm/sec) was similar in the three groups (idiopathic: 60 +/- 16, ischemic: 58 +/- 20, control: 56 +/- 22; P = NS), whereas the late diastolic transmitral flow velocity was lower but not significantly different in idiopathic compared to ischemic cardiomyopathy, and in both was lower than control (26 +/- 12 vs. 34 +/- 13 vs. 44 +/- 14, respectively; P < 0.05). Vmax. and Vp were similar in idiopathic and ischemic cardiomyopathy and greater than control (44.6 +/- 13.6 vs. 48.2 +/- 18.3 vs. 26.9 +/- 6.2; P < 0.05, and 34.6 +/- 13.4 vs. 30.8 +/- 10.9 vs. 16.7 +/- 3.7, respectively; P < 0.05). ACTEF was lower in idiopathic than in ischemic cardiomyopathy and in the latter it was similar to control (18 +/- 10% vs. 32 +/- 10% vs. 36 +/- 10%, respectively; P < 0.05). Moreover, ACTEF was inversely related to left atrial tension at end-of atrial systole both in idiopathic and in ischemic cardiomyopathy (r2 = 0.52, P = 0.001 and r2 = 0.57, P = 0.0007, respectively). However, at any given level of left atrial tension at end of atrial systole, ACTEF was lower in idiopathic than ischemic cardiomyopathy. CONCLUSION: Left atrial systolic function is depressed in idiopathic and preserved in ischemic dilated cardiomyopathy despite similar left atrial loading conditions. This finding suggests left atrial myopathy in the former, and may be related to the differences in the response to medical treatment and clinical outcome observed between the two conditions.

Plasma antioxidants: evidence for a protective role against reactive oxygen species following cardiac surgery.

Total plasma antioxidant status (TPAS), lipid peroxide concentration (LPX) and cardiac troponin T (cTnT) were measured in 24 patients undergoing coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). Samples were obtained preoperatively and at 1.5 h, 6 h, 24 h and 72 h after CPB. The absolute TPAS values were significantly lower at 1.5 h, 6 h, 24 h and 72 h after CPB than were preoperative values (P < 0.05). The LPX concentration was significantly elevated at 1.5 h after CPB (P < 0.05). Cardiac troponin T concentrations were significantly elevated at all time points postoperatively (P < 0.05). Preoperative TPAS values were significantly correlated with the magnitude of fall in TPAS at 1.5 h (P < 0.05). The greater the fall in TPAS between 0 and 1.5 h, the less LPX was formed between 0 and 1.5 h. The LPX at 1.5 h displayed a significant correlation with cTnT release from myocardial myocytes (P < 0.05). These data provide evidence for the first time that the consumption of antioxidants during CABG surgery with CPB protects against the production of reactive oxygen species and subsequent myocyte necrosis. Furthermore, the availability of protective antioxidants is dependent upon preoperative TPAS.

Lipid peroxidation, antioxidant status and troponin-T following cardiopulmonary bypass. A comparison between intermittent crossclamp with fibrillation and crystalloid cardioplegia.

OBJECTIVE: Intermittent crossclamp with fibrillation affords equivalent myocardial protection to cold crystalloid cardioplegia in patients undergoing elective coronary artery surgery. This study is a direct comparison between the two techniques with regards to free radical activity. METHODS: The study design was part of a prospective randomised trial. We studied 24 consecutive patients with ejection fraction of 30% or greater undergoing elective coronary artery surgery. Patients were randomised into two groups. In group 1 (n = 13) the myocardium was protected by intermittent aortic cross clamping with fibrillation and group 2 (n = 11) by antegrade cold crystalloid cardioplegia. The determinants of free radical activity were serial peripheral venous samples for lipid peroxidation and plasma antioxidant status (before and at 1, 6, 24 and 72 h after the end of cardiopulmonary bypass). The determinant of the efficacy of myocardial protection was serial peripheral venous samples of cardiac troponin-T taken at the same time intervals. RESULTS: The groups were similar with respect to age, sex distribution, preoperative ventricular function, left main stem disease, number of grafts and bypass times. Lipid peroxidation measurements at the 1 h time point were higher than preoperative values (7.24 +/- 1.19 vs. 4.48 +/- 0.69 and 9.36 +/- 1.46 vs. 4.98 +/- 1.02 (mean +/- S.E) in groups 1 and 2, respectively (units in mmol/l) thereafter values decreased to near preoperative values by 72 h. There was no significant difference between the groups (P = 0.42). Total plasma antioxidant status values at the 1 h time point were lower than the preoperative values for all patients (1.33 +/- 0.07 vs. 1.63 +/- 0.06 and 1.42 +/- 0.07 vs. 1.63 +/- 0.05 (mean +/- standard error) in groups 1 and 2, respectively, (units in mmol/l) and thereafter at the subsequent time points increased but never attained their preoperative value. There was no statistically significant difference between the two groups (P = 0.59). Troponin-T measurements showed no significant difference between the two groups at all time points (P = 0.2217). CONCLUSIONS: This study shows that lipid peroxidation is initially elevated and the defence mechanisms against oxygen free radicals-antioxidant status'-are depressed following cardiopulmonary bypass. The degree of oxygen free radical activity produced during ischaemia and reperfusion was similar in both types of myocardial protection employed in this study.

Minimally invasive coronary revascularization through parasternal incisions without cardiopulmonary bypass.

BACKGROUND: We report the results of minimally invasive coronary revascularization without cardiopulmonary bypass through miniparasternal incisions. METHODS: This procedure was performed in 40 patients with disease in the left anterior descending, first diagonal, and right coronary arteries. After a 5- to 7-cm left vertical parasternal incision and removal of two costal cartilages, the left internal mammary artery was harvested up to the 2nd rib. The left anterior descending artery was occluded by means of two polydioxanone monofilament sutures. The anastomosis was performed with one 7-0 Prolene suture while the heart was beating. In 4 cases the left internal mammary artery was used as a sequential graft to the left anterior descending artery and the first diagonal artery. In 14 cases the right coronary artery was grafted with the right internal mammary artery through a right parasternal incision. Postoperatively, 95% of the patients underwent angiographic assessment of the anastomoses. RESULTS: We performed 52 anastomoses (34 to the left anterior descending artery, 4 to the first diagonal artery, and 14 to the right coronary artery). The mortality was 0% and the morbidity included postoperative bleeding (5%), acute renal failure (2.5%), atrial fibrillation (2.5%), and wound infection (5%). No patient had ventricular arrhythmias or circulatory problems during or after the operation. Two patients (5%) with right internal mammary artery-to-right coronary artery grafting had graft failure that required a redo operation. CONCLUSIONS: Small vertical parasternal incisions may be an alternative approach for single and multiple coronary revascularization, with a low incidence of intraoperative cardiac complications. The application of this approach to the right coronary artery, however, carries additional technical difficulties, and careful patient selection may be required to achieve optimal results.

The role of profunda femoris revascularization in aortofemoral surgery. An analysis of factors affecting graft patency.

BACKGROUND: To determine the long-term results of aortofemoral grafts using the profunda femoris artery as an outflow vessel and to determine the factors affecting the outcome of these procedures. DESIGN: Prospective study. METHODS: From 1980 to 1993, 224 profundoplasties were performed as an adjunctive outflow procedure of aortofemoral grafts in 180 patients. There were 167 men and 13 women with a mean age of 63.7 years. Severe claudication was the indication for operation in 147 limbs (65.6%), and critical ischemia in 77 (34.4%). Good runoff was present in 159 limbs (71%), while poor run-off in 65 (29%). Profundoplasty was extended distally in 67 cases (29.9%), while in the remaining 157 (70.1%) it was limited to the proximal portion of the artery. Arterial and venous patches were used alternatively for the profundoplasty. RESULTS: The 30-day mortality was 1.6% and the 5-year and 9-year survival rate was 69.7% and 49.1% respectively. Primary graft patency was 87.2% in 5 years and 78.5% in 9 years, while secondary graft patency was 90.1% in 5 years and 81.4% in 9 years. Limb salvage rate was 92.7% in 5 years and 87.6% in 9 years. There were four factors which were predictive of inferior longterm results namely; critical ischemia, poor run-off, extended profundoplasty and vein patch used for the profundoplasty. CONCLUSIONS: Angioplasty of the profunda femoris artery is a durable outflow procedure for aortofemoral graft surgery, when the above mentioned risk factors are absent; however when they do exist, the use of arterial patch for profundoplasty may improve the prognosis.

Circulatory arrest in a reoperation for brachiocephalic arterial occlusive disease.

We report a patient with multiple brachiocephalic arterial occlusive disease who suffered failure of a bifurcated aorto-carotid artery graft. Profound hypothermic circulatory arrest provided adequate cerebral protection during redo aorto-brachiocephalic arterial grafting.