Central venous catheters may be a potential source of massive air emboli during vascular procedures involving extracorporeal circulation: an experimental study.

Central venous catheters are mandatory during every major procedure involving extracorporeal circulation. Air emboli potentially could enter the circulation through this device when negative pressure is applied in the venous cannula. The following experimental study was initiated by a fatal massive air embolus during a vascular procedure involving cardiopulmonary bypass. An experimental setup was established, simulating a real scenario. The experiment was performed with a 40% glycerol/water mixture which exhibits properties and fluid dynamics close to blood. A heart-lung machine provided circulation of the fluid. The flow was adjusted according to the gravitational status. A triple-lumen central venous catheter with one line open to air was lowered into the liquid. The disconnected lumen of the central venous catheter was manipulated so it approached and was located in close proximity to the venous cannula. An air flow of up to 300 ml/min could be obtained from the central venous catheter with a flow in the cardiopulmonary bypass circuit of 2.3 L/min. A linear relationship was observed between flow in the circuit and air flow. Consecutive measurements proved consistent with acceptable results, proving that a disconnected central venous catheter might, under certain circumstances, be a source of massive air emboli during cardiopulmonary bypass.

Renal function after cardiopulmonary bypass surgery in patients with impaired renal function. A randomized study of the effect of nifedipine.

BACKGROUND AND OBJECTIVES: Postoperative acute renal failure predicts morbidity and mortality. We investigated the effect of nifedipine infusion on glomerular filtration rate in patients with impaired renal function undergoing cardiopulmonary bypass surgery. METHODS: Twenty patients accepted for coronary bypass and/or heart valve surgery were enrolled prospectively and randomized to nifedipine infusion or no treatment. Males and females with creatinine 150 micromol L(-1) and 130 micromol L(-1), respectively, were included. Patients with unstable angina pectoris, ejection fraction 35% and those on dialysis were excluded. Glomerular filtration rate was measured preoperatively and 48 h postoperatively. Creatinine clearance was measured preoperatively and 0-4, 20-24 and 44-48 h postoperatively. There were no statistically significant differences in patient characteristics. Biochemical markers in plasma and urine were measured before and 48 h after surgery. RESULTS: The mean +/- SD preoperative glomerular filtration rates were 32.2 +/- 11.5 and 31.4 +/- 17.0 mL min-1 per 1.73 m2 in the nifedipine and control groups (P = 0.90), respectively. There was no statistically significant change in the glomerular filtration rate or in creatinine clearance over time within or between groups. A linear mixed model showed no effect of nifedipine (P = 0.44), time (P = 0.97) or interaction of nifedipine and time (P = 0.99) on creatinine clearance. Perioperative arterial pressure was kept within predefined targets. Three patients received dialysis postoperatively, all in the control group (P = 0.21). There were no statistically significant differences between groups in changes of urinary or plasma biochemistry. CONCLUSIONS: Renal function was well preserved after cardiopulmonary bypass surgery in patients with impaired renal function when maintaining thorough intensive care surveillance. Nifedipine did not influence early postoperative renal function.

Regional cardiac expression and concentration of natriuretic peptides in patients with severe chronic heart failure.

The purpose of this study was to examine the regional cardiac mRNA expression and concentration of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) in relation to the circulating peptide concentrations in patients with chronic heart failure (CHF). The myocardial mRNA levels and peptide concentrations of BNP and ANP were analysed in seven different regions of the heart from patients undergoing cardiac transplantation. Autopsy samples from individuals without known cardiovascular disease were used as controls. The plasma levels of natriuretic peptides and their N-terminal propeptides, Nt-proBNP and Nt-proANP, were measured in the CHF patients and healthy volunteers. In the autopsy specimens, the atrial regions appeared to contain the highest peptide levels for BNP as well as ANP, the atrioventricular ratio being 12-262 and 72-637-fold, respectively. In the CHF patients there was a relative shift towards the ventricle for BNP, reducing the atrioventricular ratio to 6-16-fold. The circulating concentrations of BNP/Nt-proBNP in the CHF patients correlated closely to the BNP mRNA expression in most myocardial regions including the left ventricle (r = 0.72, P < 0.001). For circulating concentrations of ANP/Nt-proANP, such correlation were limited to the left atrium free wall (r = .66, P < 0.002). Thus, of the two natriuretic peptides, BNP/Nt-proBNP may be a better reflector of left ventricular overload.

Myocardial gene expression of leukaemia inhibitory factor, interleukin-6 and glycoprotein 130 in end-stage human heart failure.

BACKGROUND: Studies in different animal models and plasma analyses in humans suggest that members of the interleukin-6 (IL-6) cytokine family may be involved in the pathogenesis of congestive heart failure (CHF). Accordingly, we have examined IL-6-related cytokines in chronic CHF in humans by analysing gene and protein expression in myocardium derived from patients with end-stage heart failure and donor hearts. METHODS: Gene expression of cytokines/receptors of the IL-6 family was documented in myocardial samples using cDNA array hybridization and RNase protection assays. Immunohistochemistry was used to detect leukaemia inhibitory factor (LIF), IL-6 and glycoprotein 130 (gp130) in myocardial tissues. RESULTS: Myocardial gene activity was documented for the majority of IL-6 family cytokines and their receptors. Immunohistochemical analysis localized IL-6, LIF and their common receptor subunit gp130 to myocytes and vascular smooth muscle cells. LIF mRNA levels were enhanced in the left ventricles of CHF patients relative to the left ventricles of donor hearts (patients 4.6 +/- 4.7 vs. donors 0.3 +/- 0.3, P < 0.005). Myocardial IL-6 and gp130 mRNA levels were not statistically different between patients and donors, but in contrast to LIF mRNA expression in heart explants, gp130 mRNA levels were significantly higher in left atrium compared with left ventricle in both patients and donors. CONCLUSIONS: Both mRNA and proteins of gp130 and its ligands IL-6 and LIF are expressed in both nonfailing and failing human myocardium. The elevated LIF mRNA levels in left ventricles from patients with end-stage heart failure suggest a role for LIF in the pathogenesis of CHF.

Transthoracic intra-aortic balloon pump in open heart operations: techniques and outcome.

OBJECTIVE: During open heart surgery, direct transthoracic insertion of the intra-aortic balloon pump (IABP) is an alternative to the routine transfemoral insertion especially in the presence of severe peripheral vascular disease. METHODS: Over 19 years (1980-1998), 646 patients were treated with IABP. In 24 of them, the balloon was inserted transthoracic (TIABP) due to failure of transfemoral insertion in 13 or extensive occlusive aorto-iliac disease in 11 cases. RESULTS: Early mortality was 58.3% in patients having TIABP compared to 46.1% in patients with transfemoral IABP insertion (p > 0.2). Of the 24 patients receiving IABP transthoracic, none suffered vascular injury (i.e. perforation or dissection). Complications which could be related to TIABP occurred in 10 patients: 3 balloon ruptures, 1 mediastinal haemorrhage, 3 cerebrovascular accidents, 1 post-operative mediastinitis, and 2 late graft infections. CONCLUSIONS: TIABP is a useful alternative when transfemoral insertion of IABP is not feasible or hazardous because of occluded or severely diseased ilio-femoral arteries. Being a second choice and a more invasive treatment, transthoracic IABP is associated with increased mortality.

[Surgery in chronic pulmonary embolism]. / Kirurgi ved kronisk lungeemboli.

BACKGROUND: Chronic lung thromboembolism may develop after episodes of acute lung emboli. Instead of being resoluted, the thromboembolic material is incorporated into the walls of the lung arteries causing obstruction of the blood flow. Secondarily, pulmonary hypertension develops and patients experience increasing dyspnoea on exertion. In chronic pulmonary thromboembolism, drug therapy is of little benefit. Surgical thromboendarterectomy of lung arteries has emerged as an effective treatment for these very sick patients. MATERIALS AND METHODS: This paper discusses our experience with seven patients who underwent pulmonary thromboendarterectomy during the five-year period 1995-99 at our institution. The preoperative and postoperative haemodynamic evaluation of all patients were similar. RESULTS: For five patients the working capacity was significantly improved, one had limited symptomatic effect, and one died perioperatively due to massive surgical bleeding. INTERPRETATION: Pulmonary thromboendarterectomy may be indicated in selected patients with severe dyspnoea due to pulmonary hypertension secondary to chronic pulmonary thromboembolism.

Omega-3 fatty acids improve blood pressure control and preserve renal function in hypertensive heart transplant recipients.

BACKGROUND: Hypertension and cyclosporine-induced nephrotoxicity are common complications in heart transplant recipients. Omega-3 fatty acids may prevent blood pressure rise early, but have not been studied long-term after heart transplantation. METHODS AND RESULTS: Forty-five clinically stable hypertensive heart transplant recipients were studied 1-12 years after transplantation and randomized in a double-blind fashion to receive either 3.4 g of omega-3 fatty acids daily or placebo for 1 year. Ambulatory 24 h blood pressure monitoring and haemodynamic studies were performed before randomization and at the end of the study. Systolic blood pressure increased by 8+/-3 mmHg (P<0.01) in the placebo group, with a non-significant increase in diastolic blood pressure of 3+/-2 mmHg (P=0.10), accompanied by a 14% increase in systemic vascular resistance (P<0.05). In contrast, no change in blood pressure or systemic vascular resistance was recorded in the omega-3 group. Plasma creatinine increased (P<0.01) and glomerular filtration rate decreased (P<0.05) in the placebo group, while no changes were observed in the omega-3 group. The antihypertensive effect was related to an increase in serum eicosapentaenoic and docosahexaenoic acid. CONCLUSION: Treatment with omega-3 fatty acids may reduce the long-term continuous rise in blood pressure after heart transplantation and may offer a direct or indirect renoprotective effect, making these fatty acids a potentially attractive treatment for post-transplant hypertension.

Intraaortic balloon pumping for predominantly right ventricular failure after heart transplantation.

BACKGROUND: Right ventricular failure from elevated pulmonary vascular resistance in the recipient is a main cause of early mortality after heart transplantation. When pharmacologic treatment is insufficient, mechanical circulatory assistance has been used to support the failing right ventricle. Considering right and left ventricular interdependence, we investigated whether intraaortic balloon counterpulsation (IABP) might also alleviate predominantly right ventricular dysfunction after heart transplantation. METHODS: Among 278 cardiac recipients, 12 adult patients underwent mechanical circulatory support for cardiac allograft dysfunction. Five patients were treated with percutaneous IABP for early postoperative low cardiac output syndrome characterized by predominantly right ventricular failure. Clinical data and hemodynamic variables were recorded before and during IABP treatment. RESULTS: Cardiac index (CI) and mean arterial pressure (MAP) increased (CI 1.7 +/- 0.1 to 2.5 +/- 0.2, MAP 53 +/- 12 to 71 +/- 7, p < 0.05) within 1 hour after IABP, whereas central venous pressure (CVP) and pulmonary artery wedge pressure (PAWP) decreased (CVP 21.6 +/- 1.7 to 13.8 +/- 3.1, p < .05; PAWP 14.8 +/- 4.9 to 12.4 +/- 3.7, nonsignificant). Within the next 12 hours, CI and mixed venous oxygen saturation increased (p < 0.05) and pulmonary artery pressure decreased (p < 0.05). All 5 patients were weaned successfully and 4 are long-term survivors with adequate cardiac performance at 1 year follow-up. CONCLUSIONS: Intraaortic balloon pumping is a minimally invasive circulatory assist device with proved efficiency in low cardiac output syndromes. This report shows that low output syndrome caused by predominantly right ventricular allograft failure may be an additional indication for IABP.

Myocardial expression of CC- and CXC-chemokines and their receptors in human end-stage heart failure.

OBJECTIVES: Chemokines regulate several biological processes, such as chemotaxis, collagen turnover, angiogenesis and apoptosis. Based on the persistent immune activation with elevated circulating levels of chemokines in patients with congestive heart failure (CHF), we have hypothesised a pathogenic role for chemokines in the development of CHF. The objective of this study was to examine mRNA levels and cellular localisation of chemokines and chemokine receptors in human CHF. METHODS: We examined explanted hearts from ten patients with end-stage heart failure (all chambers) and in ten organ donors using an RNase protection assays and immunohistochemical techniques. RESULTS: Our main findings were: (i) expression of eight chemokine and nine chemokine receptor genes in both failing and nonfailing myocardium, (ii) particularly high mRNA levels of monocyte chemoattractant protein (MCP)-1 and CXC-chemokine receptor 4 (CXCR4), in both chronic failing and nonfailing myocardium, (iii) decreased mRNA levels of MCP-1 and interleukin (IL)-8 in the failing left ventricles compared to failing left atria, (iv) decreased chemokine (e.g., MCP-1 and IL-8) and increased chemokine receptor (e.g., CCR2, CXCR1) mRNA levels in failing left ventricles and failing left atria compared to corresponding chambers in the nonfailing hearts and (v) immunolocalisation of MCP-1, IL-8 and CXCR4 to cardiomyocytes. CONCLUSION: The present study demonstrates for the first time chemokine and chemokine receptor gene expression and protein localisation in the human myocardium, introducing a new family of mediators with potentially important effects on the myocardium. The observation of chemokine dysregulation in human end-stage heart failure may represent a previously unknown mechanism involved in progression of chronic heart failure.

[Cardiac tumors]. / Svulster i hjertet.

BACKGROUND: Tumours of the heart are rare, but of great clinical interest as the majority are benign and amenable to radical excision. MATERIAL AND METHODS: We report on 30 patients with cardiac tumours resected at the National Hospital, Oslo, Norway from 1990 to 1999. Data were obtained from patient files. RESULTS: 27 patients had benign tumours, 25 of which were myxomas predominantly located in the left atrium. One patient had a primary malignant tumour (rhabdomyosarcoma) and two had secondary malignant tumours (metastases from malignant tumours). All patients were alive at follow-up four to ten years after operation. INTERPRETATION: Patient with benign tumours are cured by surgery, whereas in malignant primary tumours the surgery will most often be palliative. Surgery for cardiac metastases may be indicated in selected symptomatic patients.

[Heart transplantation in Norway]. / Hjertetransplantasjon i Norge.

The first heart transplantation in the Nordic countries was performed at Rikshospitalet, Oslo in 1983. In this paper, we present our experience with this treatment up to 1999. 317 heart transplantations have been performed, an average of 23 transplantations per year. 82% of the recipients were males; 50% had heart failure due to coronary heart disease. Mean age of the recipients was 47 years (range 1-64). Our indications and contraindications are similar to most other transplantation centres. Triple immunosuppression with ciclosporin, prednisolone and azathioprine have been used as standard treatment. The survival rate after one and ten years are 85% and 53% respectively, with a significantly higher survival rate among recipients younger than 50 at transplantation, especially if the graft was from a donor younger than 35 years. The most common early postoperative complications were acute cellular rejections and infections. Transplant accelerated coronary heart disease and cancer were the main causes of late death. We believe that close co-operation between Riskshospitalet and local centres will provide the best treatment for patients needing a heart transplant.

[Lung transplantations--methods, indications and results 1986-1998]. / Lungetransplantasjoner--metoder, indikasjoner og resultater 1986-98.

The National Hospital is the national centre for organ transplantation in Norway, and heart-lung-transplantation was introduced at the hospital in 1986. In this report, methods, patient selection and the current expectations of the various forms of lung transplantation are described. Heart-lung transplantation and bilateral lung transplantation have been used in patients in which a diseased heart or a native lung left behind would create serious problems in the postoperative period, thus we select patients to unilateral lung transplants whenever it is feasible. Due to a severe lack of lung transplants, and based on results of heart-lung and lung transplantation at other transplantation centres, we apply different upper age limits to the various transplantation procedures. 98 lung transplantations have been performed at Rikshospitalet, 96 of them after 1990; 15 heart-lung transplantations, 66 single lung transplantations in 61 patients, and 17 bilateral, sequential lung transplantations. 30 day mortality is 15%. One and five years recipient survival is 70% and 34% after heart-lung transplantation, 66% and 48% after single lung transplantation, and 81% and 63% after bilateral lung transplantation. Significant bronchial complications occurred in 7% of all anastomosis performed. The results are similar to data from The International Registry for Heart and Lung Transplantation. Lung transplantation is not developed to the same level as other forms of organ transplantation. Organ shortage is the most critical factor for further development of the lung transplantation programme.

Vascular complications of the intraaortic balloon pump in patients undergoing open heart operations: 15-year experience.

BACKGROUND: The beneficial effects of the intraaortic balloon pump (IABP) in providing circulatory support must be weighed against its complications, particularly its vascular trauma. METHODS: Five hundred nine patients who underwent open heart operations at our institution and who were treated with the IABP from January 1980 through December 1994 were studied retrospectively to assess IABP-related vascular complications and their independent preoperative predictors and the implications of IABP-related vascular complications on the patients' mortality, morbidity (clinical sepsis and organ failure), and long-term survival. RESULTS: Early vascular complications occurred in 56 patients (11%) and major complications occurred in 41 patients (8%). The latter consisted of aortic perforation in 1 patient, aortoiliac dissection in 2 patients, and limb ischemia in 38 patients. Logistic regression analysis identified concomitant peripheral vascular disease (p<0.001), elevated preoperative end-diastolic pressure, small body surface area, and large catheter size (p<0.05) as independent risk factors for IABP-related major vascular complications in patients who survived the day of operation. Late IABP-related sequelae occurred in 10 patients, 9 of whom had had early vascular complications. The presence of vascular complications per se was not a significant independent factor among other risk factors for mortality, morbidity, or long-term survival. CONCLUSIONS: Careful clinical assessment of the aortofemoral vascular tree is a cornerstone of early diagnosis and early intervention and usually prevents limb loss. The significant decrease in major vascular complications that has occurred over the last 5 years can be explained by the increased use of catheters with smaller diameters. The timing of IABP insertion in relation to operation and the duration of IABP use were the only device-related risk factors identified for morbidity and survival.

Thyroid function during and after cardiopulmonary bypass in children.

BACKGROUND: The aim of the study was to elucidate the changes in thyroid function during and after cardiopulmonary bypass (CPB) in children. METHODS: Triiodothronine (T3), thyroxine (T4), free thyroxine (FT4) and thyroid-stimulating hormone (TSH) were determined preoperatively, at specific times throughout CPB, and serially up to 48 h postoperatively, in 10 children (median age 35, range 23-68 months) undergoing elective surgery for congenital heart disease. RESULTS: T3 decreased from 2.01 +/- 0.08 preoperatively to 0.94 +/- 0.10 nmol/l 24 h postoperatively (P < 0.05). T4 levels followed a pattern similar to changes in T3. FT4 increased from 17.4 +/- 0.7 preoperatively to 30.0 +/- 0.4 pmol/l after 30 min of CPB (P < 0.05). TSH decreased from 2.44 +/- 0.43 preoperatively to 0.93 +/- 0.21 24 h postoperatively (P < 0.05). CONCLUSION: T3, T4 and TSH are significantly depressed after open heart surgery in children.

Up to eight years' follow-up of 997 patients receiving the CarboMedics prosthetic heart valve.

BACKGROUND: The aim of the study was to evaluate our clinical experience with the CarboMedics Heart Valve Prosthesis. METHODS: Nine hundred ninety-seven consecutive patients underwent mechanical valve implantation (aortic, 771; mitral, 169; double, 52; tricuspid, 5) with this prosthesis from September 1987 through December 1993. The mean age was 62.3+/-13.7 years (range, 0.4 to 84 years); 56.6% (564 patients) were men. Four hundred seventy patients (47.1%) underwent additional surgical procedures. Mean follow-up was 4.1+/-2.2 years (range, 0 to 8.3 years) with a total of 4,040 patient-years. RESULTS: Early mortality was 5.0% (50/997; aortic, 4.4%; mitral, 6.4%; double, 9.6%). Late mortality was 14.8% (140/947). Survival at 7 years was 75.9%+/-1.8% (aortic, 78.4%+/-2%; mitral, 70.7%+/-4.5%; double, 60.8%+/-7.4%). When matched for sex and age and compared with the normal Norwegian population, our patients had an increased standard mortality ratio in both men (1.9+/-0.4) and women (2.9+/-0.6). The linearized rate of major thromboembolism was 0.9% per patient-year, valve thrombosis 0.2% per patient-year, major bleeding event 0.6% per patient-year, paravalvular leak needing reoperation 0.5% per patient-year, prosthetic valve endocarditis 0.1% per patient-year, and of all reoperations 0.6% per patient-year. CONCLUSIONS: The CarboMedics Heart Valve Prosthesis has incidences of morbid events comparable with or better than reported for other mechanical valves.

Immunoglobulin prolongs survival of pig kidneys perfused ex vivo with human blood.

Intravenous immunoglobulin (IVIG) (Octagam), was used to determine the effect on hyperacute rejection in an ex vivo xenograft model. Six pig kidneys were perfused with IVIG and fresh human AB blood, and six control pig kidneys were simultaneously perfused with albumin and blood from the same donation. The survival of the IVIG-perfused xenografts (median, 6.5 h) was significantly (P = 0.03) longer than the albumin-perfused xenografts (median, 3.5 h). Complement was activated in both groups. The administration of IVIG to the perfused blood resulted in immediate and significantly higher complement activation in the fluid phase as compared with the albumin group. At rejection the fluid phase complement activation was higher in the IVIG group than in the albumin group for C1rs/C1inh complexes, C4bc, Bb and TCC. At the time of rejection both the albumin and the IVIG group demonstrated interstitial tubular haemorrhage, vasculitis or necrosis of glomerular capillaries and glomerular microthrombi. IgM, C1q, C3c, C4 and fibrin were located in arteries and glomeruli and IgG in the interstitium in both groups at rejection. The fluid phase findings are consistent with a modulatory effect of IVIG on complement activation by deviating the classical pathway activation towards the fluid phase. The prolonged survival of the IVIG-perfused kidneys suggests that IVIG may be useful to dampen hyperacute rejection.

Minimally invasive direct coronary artery bypass grafting without cardiopulmonary bypass in combination with intraoperative percutaneous transluminal coronary angioplasty for palliative coronary revascularization in a heart transplant recipient.

The use of minimally invasive direct coronary artery bypass grafting without cardiopulmonary bypass in combination with intraoperative percutaneous transluminal coronary angioplasty for myocardial revascularization in a heart transplant recipient is reported.