Biomedical subjects
Publications and source records attributed to B M Fabri.
A patient who had undergone urgent coronary artery bypass grafting for unstable angina developed a fatal left ventricular free wall rupture in the early postoperative period. Heart rupture following surgical revascularisation has not been reported before.
The requirement for hypothermia in myocardial protection has recently been questioned. Between October 1990 and May 1991, diastolic arrest was achieved using continuous perfusion with normothermic, hyperkalaemic blood in 257 consecutive patients undergoing cardiac surgery. The mean age was 59.8 +/- 9.3 years (range 28-84 years). Coronary artery surgery was performed in 210 patients, valve replacements in 18, combined procedures in 22, and 7 patients had miscellaneous procedures. Eleven patients (4.3%) had undergone previous cardiac surgery, and 65 (25.3%) required urgent or emergency operations. Hyperkalaemic blood (7-20 mmol/l) was delivered antegradely in 190 (72.8%) patients (mean aortic root pressure 60-80 mmHg), retrogradely in 62 (25.3%) patients (mean coronary sinus pressure less than 40 mmHg), and by a combined route in 5 (1.9%). Sinus rhythm returned immediately after removal of the aortic clamp in 235 (91.4%) patients. Weaning from bypass was achieved without circulatory support in 207 (82.5%) patients. Of 233 patients undergoing non-emergency coronary artery surgery, single valve or combined procedures, 11 died, giving an operative mortality of 4.7%. Of 155 patients with good left ventricular function requiring coronary artery surgery, 3 (1.9%) died. The in-hospital mortality for the group as a whole was 7.3%. Sixteen (6.2%) patients sustained perioperative myocardial infarctions; of these 6 died. We conclude that continuous, normothermic, hyperkalaemic arrest is a simple and safe method of myocardial protection. It may avoid the damage associated with hypothermia, ischaemia and reperfusion.
Early rupture of a saphenous vein graft used for coronary artery surgery has not been previously reported. In a 69-year-old man having a third coronary by-pass procedure, one of the saphenous vein grafts ruptured on the 8th postoperative day. The other vein graft showed marked aneurysm formation at two sites. Histological examination of the ruptured graft revealed that this was due to a bacterial infection within the wall of the vein. Although he survived an emergency operation to control the haemorrhage and replace the ruptured graft, he died some days later of mediastinitis. It appeared that both the rupture of the graft and the ensuing mediastinitis were due to a primary infective process within the saphenous vein used for the graft.
OBJECTIVE: To test the hypothesis that selective decontamination of the digestive tract improves outcome in cardiac surgical patients. DESIGN: Prospective, consecutive, controlled trial over two 4-month periods. SETTING: Eight-bed, open-plan postcardiac surgery ICU. PATIENTS: All patients undergoing cardiac bypass surgery were eligible. Patients requiring endotracheal intubation for greater than 4 days were included in the analysis. In the initial 4 months, 12 (8.5%) of 141 patients required greater than 4 days of intubation. These 12 patients were not treated with selective decontamination of the digestive tract. We therefore used these patients as the control group. In the second 4-month period, 12 (6.6%) of 180 patients were treated with selective decontamination of the digestive tract and formed the study group. MAIN OUTCOME MEASURES: The primary measure was mortality. Secondary measures included oropharyngeal decontamination and the presence of lower airway infection. INTERVENTIONS: Cephradine prophylaxis. The study group received every 6 hrs 4 mL orally and 20 mL intragastrically a suspension of antimicrobial agents (tobramycin 80 mg, polymyxin E 100 mg, amphotericin B 500 mg), starting on postoperative day 1. The control group did not receive any oral antimicrobial agents. RESULTS: Mortality rate was significantly (p less than .05) reduced from eight (66%) of 12 patients in the control group to two (16.7%) of 12 patients in the selective decontamination of the digestive tract group. No differences in oropharyngeal decontamination or lower airway infection rates between the two groups were found. CONCLUSIONS: There is a reduced mortality rate in patients receiving selective decontamination of the digestive tract. However, the reader should recognize the small sample size studied. A simple suspension of the antimicrobial agents failed to rid the oropharynx of bacteria.
We report a series of 21 consecutive patients undergoing combined multiple valve procedures and myocardial revascularisation between 1978 and 1988. There were 11 females and 10 males with a mean age of 58.5 (+/- 5.7) years. All patients were in NYHA Class 2 or more and 12 patients (57%) had angina. The mean left ventricular segment score was 7.9 (+/- 3.3). Five patients had undergone previous cardiac surgery. In all patients the aetiology of the valvular dysfunction was rheumatic. The first patient in the series was operated on using ischaemic arrest. The remaining 20 operations were performed using cardioplegia (2 crystalloid, 18 blood). A mean of 1.63 grafts per patient were inserted. There were 20 aortic valve replacements, 1 aortic valvotomy, 13 mitral valve replacements, 7 open mitral valvotomies, 1 mitral valve repair, and 1 tricuspid valve replacement. 1 patient had 3 valves replaced. Five deaths occurred in the series; all were due to low cardiac output and occurred prior to discharge from hospital. Follow-up ranged from 7 to 111 months (mean = 46 +/- 33). Three patients developed mitral paravalvular leaks, two of which were successfully repaired at 2 months and 2 years postoperatively. The third was asymptomatic. There were no late deaths and all survivors improved to NYHA Class 1 and had no angina. Early death was associated with increased perfusion time (p less than 0.01), the need for postoperative inotropic support (p less than 0.01) and high blood loss. No preoperative predictors of early death were identified. Multiple valve procedures and myocardial revascularisation carry a significant early mortality but are justified by the satisfactory long-term outcome.
We examined the cases of 31 patients over the age of 50 years undergoing operative closure of isolated ostium secundum atrial septal defect. The lesion had been diagnosed in all cases prior to cardiac catheterization. To assess the importance of pre-operative data on surgical outcome, the patients were first divided into three groups according to mean pulmonary artery pressure (PAP): less than 16 mmHg (Group A), 16-30 mmHg (Group B) and greater than 30 mmHg (Group C). Symptomatic improvement occurred in all groups but more patients in Group C, although symptomatically improved, remained short of breath and in atrial fibrillation than in Group A. Patients in Group A had a higher actual forced vital capacity expressed as a percentage of the predicted value (FVCa/FVCp) than patients in Group B or Group C (P less than 0.015). There was a good correlation between FVCa/FVCp and percentage oxygen saturation of the arterial blood (P less than 0.0009). This simple non-invasive investigation was therefore found to correlate with previously documented parameters, pulmonary artery pressure and percentage oxygen saturation of the arterial blood, affecting surgical outcome. Patients were also divided into groups according to FVCa/FVCp: less than 75% (Group 1), 50-75% (Group 2) and less than 50% (Group 3). Postoperative symptoms were more common in Group 3 than in Group 1. We conclude that respiratory function tests, as well as measurement of pulmonary artery pressures, are useful in predicting improvement following atrial septal repair.
Using regionally implanted sonomicrometry crystals, we have evaluated a new index of regional function (normalised systolic shortening [NSS]) which integrates the systolic and diastolic properties of the left ventricle. Eight dogs (group I) were subjected to standard cardiopulmonary bypass and 45 min of hypothermic (10 degrees C), hyperkalaemic (25 mEq) crystalloid cardioplegia. Seven dogs (group II) underwent occlusion of the left anterior descending (LAD) coronary artery 5 min prior to initiation of cardiac arrest. The occlusion was released after 20 min, before the second cardioplegia infusion. Sarnoff left ventricular (LV) function curves were performed pre-arrest and 20, 40 and 60 min after removal of the cross-clamp. Regional assessment of myocardial function showed 55% +/- 3%, 70% +/- 3% and 70% +/- 5% recovery in the LAD region and 52% +/- 2%, 83% +/- 3% and 88% +/- 4% recovery in the circumflex (Cx) region of group I. In group II the LAD region recovered 27% +/- 1%, 31% +/- 3% and 38% +/- 3% and the Cx region showed 61% +/- 3%, 55% +/- 1% and 65% +/- 5% recovery. Comparison of the new index of ventricular function to standard indices of regional and global function demonstrate that the latter underestimate the degree of myocardial dysfunction after cardioplegic arrest, particularly in situations of acute regional myocardial ischaemia and uneven myocardial protection. The utilization of this index should provide a better standard for the more accurate assessment of interventions designed to decrease myocardial injury during cardioplegic arrest.
We conducted a prospective, randomized, controlled trial comparing homologous blood consumption between groups of patients receiving conventional mediastinal drainage (group 1) or reinfusion of shed mediastinal blood (group 2) using hard-shell cardiotomy reservoir. One hundred consecutive patients who had elective coronary artery or valvular operations were studied. The two groups were comparable with regard to age, sex, weight, preoperative and postoperative hemoglobin levels, and surgical procedure. Group 2 patients had their shed mediastinal blood reinfused for up to 18 hours postoperatively; otherwise, the two groups were treated identically. For groups 1 and 2, average mediastinal blood losses were 705 +/- 522 and 822 +/- 445 mL and homologous blood consumption was 3.83 +/- 2.58 and 3.15 +/- 2.05 U, respectively (neither measure was significantly different). However, if blood losses exceeded 500 mL, there was a statistically significant reduction in homologous blood requirements in group 2 as compared with matched controls in group 1. This difference was most significant in patients with the greatest mediastinal losses.
A case of vocal cord paralysis following mobilisation of the internal mammary artery is described. Of the various possible mechanisms, the most likely in this case is damage to the vagus nerve in the root of the neck, where it passes close to the origin of the internal mammary artery. Diathermy may have caused the damage, and this may be avoided by using a disposable automatic clip applier on any branches of the mammary artery in the area.
Systemic and cardiac metabolism of thromboxane was studied in a canine model (n = 13) of standard cardiopulmonary bypass and surgical cardioplegia. Sterile techniques were applied and no donor blood was used. Systemic samples (thoracic aorta) and transcardiac gradients (coronary sinus - aortic root) were obtained (1) 5 minutes after cannulation, (2) 20 minutes after the onset of partial bypass, (3) 5 seconds after the first administration of cardioplegic solution (CP-1), and (4) 5 seconds after the second administration of cardioplegic solution (CP-2). Cardioplegic doses were administered 30 minutes apart and consisted of 500 ml of hypothermic (8 degrees C), hyperkalemic (25 mEq potassium chloride) solution infused into the aortic root at 60 to 70 mm Hg. Thromboxane B2 was determined by a double-antibody radioimmunoassay (picograms per milliliter +/- standard error of the mean). Onset of partial bypass was followed by a significant rise in systemic arterial thromboxane B2 levels: after cannulation, 115 +/- 21 pg/ml; after the onset of partial bypass, 596 +/- 141 pg/ml; p less than 0.01). Significant transcardiac thromboxane B2 gradients were found during the first and second cardioplegic washouts (CP-1: aortic root 73 +/- 12 pg/ml, coronary sinus 306 +/- 86 pg/ml, p less than 0.01; CP-2: aortic root 65 +/- 11 pg/ml, coronary sinus 355 +/- 98 pg/ml, p less than 0.01). Transcardiac gradients of 6-keto-prostaglandin F1 alpha and thromboxane B2 were obtained at CP-1 and CP-2. Gradients of 6-keto-prostaglandin F1 alpha were not different from thromboxane B2 gradients during CP-1 but were significantly higher than thromboxane B2 gradients during CP-2. In a subgroup of five dogs, transcardiac thromboxane B2, lactate, and platelet gradients were measured simultaneously. Cardiac thromboxane B2 generation was found only in the presence of cardiac lactate production. Transcardiac platelet gradients were significantly higher at CP-1 (13,900 +/- 3,000/mm3) than at CP-2 (4,000 +/- 1,230/mm3) (p less than 0.05), whereas thromboxane B2 gradients were similar at CP-1 and CP-2. Our study demonstrates that thromboxane B2 is released into the coronary circulation during surgical cardioplegic arrest with anaerobiosis.
No reliable, noninvasive technique is currently available for the early detection of cardiac transplant rejection. In this study, pulse nuclear magnetic resonance (NMR) spectroscopy was used (20 MHz) to detect cardiac allograft rejection in rats. Proton spin-lattice relaxation time (T1), proton spin-spin relaxation time (T2), and water content were measured in both recipient and donor hearts at 2, 4, 6, and 8 days after transplantation. Pathologic specimens were scored on a 0 to 4+ scale of increasing evidence of rejection by light microscopy. Three kinds of heterotopic transplants were performed for a total of 90: (1) Lewis rats received Lewis rat isografts, (2) Lewis rats received Brown Norway rat allografts, and (3) Lewis rats received cyclosporin A-treated allografts (15 mg/kg/day). T1 in group 2 was significantly higher than that in group 1 as early as day 2 (670 + 25 vs 616 + 11 msec, p less than .001), when histologic scores were not different. T2 in group 2 was also higher than that in group 1 (48.0 +/- 5.0 vs 41.1 +/- 2.6, p less than .005). T1 and T2 in group 2 increased from day 4 and correlated well with the water content of the hearts (r = .70 and r = .75, respectively). Cyclosporin A completely suppressed the increase of T1 and T2 in group 2. Treatment with cyclosporin also suppressed the histologic rejection scores. Our data suggest that proton relaxation time measurement may be a sensitive technique for detecting the onset of rejection and examining the therapeutic effects of cyclosporin. NMR imaging, which highlights T1 and T2 separately, should provide a sensitive noninvasive means of assessing myocardial graft rejection.