Comparison of magnetic resonance imaging and transthoracic echocardiography for the identification of LV mass and volume regression indices 6 months after mitral valve repair.

BACKGROUND: Magnetic Resonance Imaging (MRI) and transthoracic echocardiography have been shown to be noninvasive highly sensitive diagnostic tools to identify changes in LV mass and volume. We therefore investigated the effects of mitral valve repair (MVR) on LV function parameters including ejection fraction (EF; %), indices of LV mass (LVMI; g/m2) and volume (LVEDVI, LVESVI; mL/m2) as detected by MRI and echocardiography. METHODS: Eight consecutive patients (mean age 53.3 +/- 10.0 years) with severe mitral regurgitation (MR; grade III-IV), normal LV function and sinus rhythm were included in this prospective study. Cine MRI and transthoracic M-mode echocardiography were performed pre-operatively, as well as 6 months post-op, to identify changes in EF and in LV mass and volume. Data are given as mean +/- standard deviation. RESULTS: Post-op MR was grade 0-I in all patients. Early mortality and late mortality was 0%. EF by either method did not change significantly within the follow-up period. A significant improvement of indices of LV mass and volume was detected by Cine MRI and echocardiography within 6 months following surgery (LVMIMRI: pre-op: 76.3 +/- 20.1 vs. post-op: 66.5 +/- 14.3, p < 0.05; LVMIEcho: pre-op: 184.2 +/- 38.1 vs. post-op: 136.5 +/- 28.4, p < 0.05. LVEDVIMRI: pre-op: 119.3 +/- 26.0 vs. post-op: 75.4 +/- 13.1, p < 0.05; LVEDVIEcho: pre-op: 97.4 +/- 28.8 vs. post-op: 69.2 +/- 13.1, p < 0.05. LVESVIMRI: pre-op: 44.6 +/- 12.0 vs. post-op: 32.5 +/- 9.5, p < 0.05; LVESVIEcho: pre-op: 29.3 +/- 8.3 vs. post-op: 21.8 +/- 4.6, p < 0.05). CONCLUSIONS: MRI and echocardiography show a significant reduction of LV volume and mass 6 months after MVR. The data show that for routine follow-up transthoracic M-mode echocardiography provides reliable information for the identification of LV mass and volume regression in patients after MVR.

Towards robotic heart surgery: introduction of autonomous procedures into an experimental surgical telemanipulator system.

The introduction of telemanipulator systems into cardiac surgery enabled the heart surgeon to perform minimally invasive procedures with high precision and stereoscopic view. For further improvement and especially for inclusion of autonomous action sequences, implementation of force-feedback is necessary. The aim of our study was to provide a robotic scenario giving the surgeon an impression very similar to open procedures (high immersion) and to enable autonomous surgical knot tying with delicate suture material. In this experimental set-up the feasibility of autonomous surgical knot tying is demonstrated for the first time using stereoscopic view and force feedback.

Effects of mid-line thoracotomy on the interaction between mechanical ventilation and cardiac filling during cardiac surgery.

BACKGROUND: Mid-line thoracotomy is a standard approach for cardiac surgery. However, little is known how this surgical approach affects the interaction between the circulation and mechanical ventilation. We studied how mid-line thoracotomy affects cardiac filling volumes and cardiovascular haemodynamics, particularly variations in stroke volume and pulse pressure caused by mechanical ventilation. METHODS: We studied 19 patients during elective coronary artery bypass surgery. Before and after mid-line thoracotomy, we measured arterial pressure, cardiac index (CI) and global end-diastolic volume index (GEDVI) by thermodilution, left ventricular end-diastolic area index (LVEDAI) by transoesophageal echocardiography and the variations in left ventricular stroke volume and pulse pressure during ventilation by arterial pulse contour analysis. RESULTS: After thoracotomy, CI increased from 2.3 (0.4) to 2.9 (0.6) litre min(-1) m(-2), GEDVI increased from 605 (110) to 640 (94) litre min(-1) m(-2), and LVEDAI increased from 9.2 (3.7) to 11.2 (4.1) cm(2) m(-2). All these changes were significant. In contrast, stroke volume variation (SVV) decreased from 10 (3) to 6 (2)% and pulse pressure variation (PPV) decreased from 11 (3) to 5 (3)%. Before thoracotomy, SVV and PPV significantly correlated with GEDVI (both P<0.01). When the chest was open, similar significant correlations of SVV (P<0.001) and PPV (P<0.01) were found with GEDVI. CONCLUSION: Thoracotomy increases cardiac filling and preload. Further, thoracotomy reduces the effect of mechanical ventilation on left ventricular stroke volume. However, also under open chest conditions, SVV and PPV are preload-dependent.

Surgical treatment of permanent atrial fibrillation using microwave energy ablation: a prospective randomized clinical trial.

OBJECTIVE: Radiofrequency or the use of microwave energy in combination with atrial size reduction during open heart surgery have been reported to be effective in up to 75% in the treatment of permanent atrial fibrillation. However, no data from prospective randomized trials using microwave energy are available. METHODS: Forty-three patients with permanent atrial fibrillation undergoing open-heart surgery were randomly stratified into treatment group receiving microwave ablation and atrial size reduction (n=24) or control group (n=19). Patients in either group were treated with amiodarone or sotalol for 3 months if sinus rhythm or any atrioventricular rhythm was successfully restored. Follow-up time points were at 3, 6 and 12 month after surgery. RESULTS: In the treatment group 22 out of 24 patients (91,7%) were successfully converted to sinus rhythm by using intraoperative microwave ablation therapy whereas only six out of 19 (31.5%) patients converted to sinus rhythm directly after surgery. At 12-month follow-up there were still a significantly higher percentage of patients in the treatment group free from atrial fibrillation when compared to control (80 vs. 33.3%, P=0.036). CONCLUSION: The preliminary data from this first prospectively randomized trial indicate that microwave ablation combined with atrial size reduction is a safe and highly efficient treatment in permanent atrial fibrillation.

[Surgical treatment of aortic valve disease in old age]. / Keine Angst vorm Klappenersatz. Auch bei Senioren ist der Nutzen meist grösser als das Risiko.

In terms of long-term survival and quality of life, excellent results with aortic valve replacement (AVR) can also be achieved in patients older than 70 years of age. An indication for this procedure is given in symptomatic patients with significant aortic valve stenosis, patients with severe acute aortic insufficiency (AI), those with signs of cardiac insufficiency but still normal left ventricular function, and asymptomatic AI patients with an ejection fraction of less than 50% and/or an end-diastolic LV diameter (EDD) of more than 75 mm or an end-systolic diameter (ESD) of more than 55 mm. Many patients with a heart defect in need of surgical treatment also have CAD as well, in which case a bypass should be performed at the same time. For AVR, both mechanical and biological prostheses are available, the latter being regarded as the method of choice in patients aged over 70. The mechanical variant requires life-long anticoagulation therapy with phenprocoumon.

Expression of endomyocardial nitric oxide synthase and coronary endothelial function in human cardiac allografts.

BACKGROUND: Inducible nitric oxide synthase (iNOS) is expressed and is functionally active in the presence of transplant arteriosclerosis. However, the early involvement of iNOS in alterations of microvascular endothelial function in the absence of preexisting lesions remains unclear; this information would be of prognostic value. We studied the course of iNOS mRNA expression, transcardiac nitric oxide production, and their potential association with microvascular coronary endothelial dysfunction in human cardiac allografts. METHODS AND RESULTS: A total of 42 patients were studied at 1, 6, and 12 months after heart transplantation. Microvascular coronary flow velocity reserve (CFVR) was tested in an endothelium-dependent (acetylcholine) and -independent manner (adenosine) using a Doppler flow wire. Endomyocardial iNOS expression was determined by reverse transcription polymerase chain reaction. iNOS protein and nitrotyrosine levels were detected by immunohistochemistry. Transcardiac plasma nitrite/nitrate (NOx) levels were measured by the Griess reaction. CFVR was impaired in 26.1% of patients (n=11) at 1 month and in 31% of patients (n=13) at 12 months after heart transplantation. Patients who developed impaired CFVR in the first year showed a significant increase in iNOS gene expression. Patients with impairment of CFVR 1 month after heart transplantation had higher levels of iNOS mRNA than patients with a normal CFVR. Patients with an initial impairment of CFVR who did not improve over time presented with significantly higher iNOS mRNA levels. iNOS protein and nitrotyrosine were expressed in the endomyocardial vessels of patients with impaired CFVR. Transcardiac NOx release was higher in patients with impaired CFVR. CONCLUSIONS: In human cardiac allografts, microvascular endothelial dysfunction is associated with an enhanced endomyocardial iNOS mRNA expression and higher transcardiac NOx production and is accompanied by the expression of nitrotyrosine protein, suggesting peroxynitrite plays a role in the disease process. The data from the present study suggest an important role for the iNOS/nitric oxide pathway in the regulation of microvascular function in the absence of preexisting atherosclerotic lesions.

Re-OPCAB vs. Re-CABG for myocardial revascularization.

BACKGROUND: The present study compared redo coronary artery bypass grafting (Re-OPCAB) techniques with conventional redo coronary artery bypass grafting (Re-CABG) with particular focus on myocardial damage and clinical outcome parameters. METHODS: Redo OPCAB (Re-OPCAB) was performed on 20 consecutive patients (15 males, mean age 63.2 +/- 9.3 years) using either the anterolateral approach for minimally invasive direct coronary artery bypass (n = 4) or the Octopus technique with regular sternotomy (n = 16). The Re-CABG group consisted of 20 consecutive patients (18 males, mean age 67.1 +/- 6.6 years). Groups did not differ in the number of atherosclerotic risk factors, or left ventricular, renal or liver function. RESULTS: Duration of surgery, number of bypass grafts and amount of transfused red blood cells did not differ significantly between both groups. Requirement of epinephrine (mg/h) within the first 24 h was lower in the Re-OPCAB group (Re-OPCAB: 0.14 +/- 0.22 vs. CABG: 0.88 +/- 0.97; p<0.01). In addition, CKMB levels at 24 h after operation were lower in the Re-OPCAB group (Re-OPCAB: 10.0 +/- 10.1 vs. Re-CABG: 38.7 +/- 28.1 U/l, p<0.001). There were no acute myocardial infarctions or deaths in the perioperative period. In the CABG group, there was a longer time period to extubation (hours) (Re-OPCAB: 9.8 +/- 3.9 vs. Re-CABG: 28.7 +/- 25.5; p<0.001), and the length of ICU stay was significantly prolonged (OPCAB: 1.3 +/- 0.5 versus Re-CABG: 4.4 +/- 8.7; p<0.001). The graft patency rate at follow-up was 95% in the Re-OPCAB group. CONCLUSION: Re-OPCAB results in decreased cardiac specific enzyme release, reduced requirement of inotropes and comparable clinical outcome in the early postoperative period. It is an appropriate alternative to conventional Re-CABG in selected patients awaiting reoperation for myocardial revascularization. Larger prospective and randomized trials are required to select the appropriate patient who benefits most from one or the other treatment regime.

Coronary flow reserve and nitric oxide synthases after cardiac transplantation in humans.

OBJECTIVE: Coronary endothelial dysfunction may precede morphological changes in both the epicardial conduit and microvascular resistance vessels in heart transplant recipients. Since the development of transplant atherosclerosis is the major limiting factor for long-term survival, the identification of early mediators of vasomotor dysfunction may be of therapeutic interest. We therefore investigated the potential relationship between the expression of nitric oxide synthases (NOS) and coronary endothelial function in human cardiac transplant recipients over time. METHODS: Forty-two human cardiac transplant recipients were studied at 1 and 12 months after heart transplantation (HTx). The microvascular coronary flow velocity reserve (CFVR) was tested for endothelium-dependent (acetylcholine) and -independent (adenosine) stimuli by intravascular Doppler flow-wire. Epicardial diameter changes were evaluated by quantitative coronary angiography. Endomyocardial inducible (iNOS) and endothelial constitutive nitric oxide synthase were determined by RT-PCR. Nitric oxide production (nitrite and nitrate (NOx)) and TNF-alpha were measured in plasma samples from the aorta and coronary sinus. RESULTS: CFVR was impaired in 26.1% (n=11) of patients at 1 month and in 31% (n=13) 12 months after HTx. iNOS-mRNA levels were significantly higher in patients with impaired endothelium-dependent CFVR. In addition, only in these patients were TNF-alpha levels higher and these correlated with plasma NOx levels at 1 and 12 months post-HTx (1 month: r=0.81, P=0.001; 12 months: r=0.62, P=0.04). CONCLUSIONS: Coronary microcirculatory dysfunction in response to acetylcholine is present in nearly 30% of patients during the first year following transplantation. These patients present with higher iNOS-mRNA expression and TNF-alpha plasma levels. Selective modulation of the TNF-alpha/iNOS-pathway may be of therapeutic value to improve coronary endothelial dysfunction in cardiac transplant recipients.

[Minimally invasive procedures in heart surgery. How does it work and who profits?]. / Minimal-invasive Verfahren in der Herzchirurgie. Wie funktionieren sie und wer profitiert?

The leading minimally invasive procedures employed in coronary surgery are minimally invasive direct coronary arterial bypass surgery (MIDCAB) and the Octopus system. These interventions are performed on the beating heart and require no extracorporeal circulation (ECC), thus avoiding the side effects, such as pulmonary or neurological complications, associated with ECC. In surgery on the mitral or aortic valve, the procedures are carried out via small incisions in the non-beating heart, and endovascular bypass systems (e.g. Port-Access) are sometimes needed for EEC. The advantages of small incisions are a reduction in the risk of infection, shorter hospital stay and, in particular, improved cosmesis. A disadvantage is the longer operating time. Only careful patients selection guarantees successful surgery.

Reduction of systemic and cardiac adhesion molecule expression after off-pump versus conventional coronary artery bypass grafting.

Cardiopulmonary bypass (CPB) and operative trauma are associated with increased expression of proinflammatory mediators. We determined the relative contribution of CPB on activation of cytokines and adhesion molecules in patients undergoing coronary revascularization by comparing them with patients receiving off-pump coronary artery bypass grafting (OPCAB). Twenty-six patients were assigned to either the OPCAB procedure using a suction device and regular sternotomy (n = 13), or were treated conventionally using extracorporeal circulation, blood cardioplegia, and hypothermic arrest (29 degrees C-31 degrees C; n = 13). Systemic levels of TNF-alpha and the soluble adhesion molecules P-selectin and intracellular adhesion molecule 1 (ICAM-1) were assayed. Immunohistochemistry was used to account for cardiac-specific expression of adhesion molecules in interventricular endomyocardial sections. Both systemic and endomyocardial expression of adhesion molecules were lower in the OPCAB group. Coronary revascularization with CPB resulted in a significant higher expression of TNF-alpha, which was associated with P-selectin and ICAM-1 expression. This was accompanied with higher catecholamine requirement in the CPB group in the early postoperative period. Despite comparable surgical trauma, the OPCAB procedure without the use of CPB and cardioplegic arrest significantly reduces systemic and cardiac adhesion molecule expression and catecholamine requirement. Since the clinical course in the early postoperative period was comparable, larger trials are required to select the appropriate patient who benefits most from one or the other treatment regime.

Coronary vasomotor dysfunction in the cardiac allograft: impact of different immunosuppressive regimens.

Immunosuppression may have an important impact on early graft coronary endothelial injury. We investigated functional and morphologic coronary alterations, myocardial expression, and cardiac release of possible mediators of allograft vasculopathy within 6 months after cardiac transplantation with respect to different immunosuppressive regimens. Epicardial and microvascular endothelium-dependent and endothelium-independent vasomotor function and epicardial intimal thickening were measured in 8 transplant recipients treated with cyclosporin A (CyA), azathioprine, and prednisone (group 1), 9 transplant recipients treated with tacrolimus (TKL), azathioprine, and prednisone (group 2), and 14 patients treated with TKL, mycophenolate mofetil (MMF), and prednisone (group 3). The gene expressions of inducible and endothelial nitric oxide synthase (iNOS and eNOS), endothelin-1, prostacyclinsynthase, and thromboxansynthase were analyzed in endomyocardial biopsy specimens using semiquantitative reverse transcription polymerase chain reaction. Transcardiac cytokine release, endothelin-1, and nitrate-release were determined from plasma samples. Epicardial endothelial dysfunction (vasoconstriction to acetylcholine > 10%) and microvascular smooth muscle cell dysfunction (flow velocity increase to adenosine and nifedipine < 2.0) were enhanced in heart transplant recipients immunosuppressed with TKL, azathioprine, and prednisone. The prevalence of epicardial dysfunction was 78% in group 2 versus 44% and 46% in group 1 and 3 (p < 0.05), respectively. The prevalence of microvascular dysfunction was 56% in group 2 versus 13% and 7% in group 1 and 3 (p < 0.02), respectively. Coronary vasomotor dysfunction was associated with increased myocardial iNOS expression (p < 0.05), decreased eNOS expression (p < 0.05), and enhanced cardiac immunoreactive interleukin-6 (p < 0.01). Coronary intimal thickening was not different between the groups. The combination of TKL and MMF appears to be superior to TKL and azathioprine (and comparable to CyA and azathioprine) concerning preservation of early coronary vasomotor function, eNOS expression, iNOS suppression as well as cardiac interleukin-6 release. This may have an important impact on subsequent development of transplant coronary atherosclerosis.

Effects of Celsior and University of Wisconsin preservation solutions on hemodynamics and endothelial function after cardiac transplantation in humans: a single-center, prospective, randomized trial.

Optimal preservation of the myocardium remains a major concern in clinical and experimental heart transplantation. The present study compared the efficacy of University of Wisconsin (UW) and Celsior preservation solution with respect to myocardial performance, epicardial and microvascular endothelial vasomotor function and myocardial expression of endothelin and nitric oxide synthases in humans. Forty-one cardiac transplant recipients received either UW (n = 20) or Celsior (n = 21) preserved hearts. Catecholamine and vasodilator requirements were assessed within the first 5 postoperative days. Left ventricular performance and endothelial function was assessed 1 month after transplantation. Endothelin and nitric oxide synthase gene expression were detected in myocardial biopsy samples. Celsior preserved hearts required significantly more catecholamines and vasodilators within the first 5 postoperative days. Myocardial performance and endothelial function were comparable 1 month after transplantation. Total ischemic time correlated with impaired endothelial function in the Celsior but not in the UW group. Endothelin and inducible nitric oxide synthase gene expression were significantly higher in the Celsior group. The results of the study show that both solutions provide myocardial protection with regard to left ventricular performance and endothelial function 1 month after cardiac transplantation. The necessity for higher vasodilator and catecholamine therapy in Celsior preserved hearts suggests post-ischemic myocardial stunning within the first 5 postoperative days. The positive correlation between impaired endothelial function and total ischemic time in the Celsior group requires longitudinal investigation in particular with regard to the development of allograft vasculopathy.

An association between microvascular endothelial dysfunction, transcardiac nitric oxide production and pro-inflammatory cytokines after heart transplantation in humans.

Endothelial dysfunction anticipates the development of transplant coronary artery disease (TxCAD) observed more than 1 year after transplantation (HTx). We investigated whether in patients early after HTx myocardial inducible and constitutive nitric oxide synthases (iNOS; cNOS) are expressed and cardiac nitric oxide production occurs. Moreover, a possible relationship to alterations in endothelium dependent and independent vasomotor function was assessed. Forty-two transplant recipients were studied 37 +/- 5 days after HTx. Microvascular coronary flow velocity reserve (CFVR) was tested endothelium dependent (acetylcholine; 30 microg/min x 5 min/i.c.) and independent (adenosine; 160 microg/min x 5 min/i.c.) by Doppler flow wire. Flow velocity increase by a factor greater than 2 was considered normal. Quantitative coronary angiography was used to assess epicardial vasomotor function in response to the same stimuli. Myocardial iNOS and cNOS gene expression were detected by semiquantitative reversed transcriptase polymerase chain reaction. Plasma nitrite levels (microM) were measured by spectrophotometry. Cytokines (TNF-alpha, IL-6; pg/ml) were measured by enzyme linked immunosorbent assay. In 26.1% of patients (n = 11; group A) an impaired endothelium dependent CFVR (1.65 +/- 0.23 increase) was observed; in 73.9% (n = 31, group B) a normal endothelium dependent CFVR (3.0 +/- 0.7 increase; P = 0.003) was observed. Myocardial iNOS and cNOS gene expression did not differ between the two groups. Transcardiac cytokine production was noted in 58.8% of patients for IL-6 and in 53.3% for TNF-alpha. Coronary sinus (CS) levels of TNF-alpha, IL-6 and nitrite were higher in group A. A significant increase in nitrite production was found only in patients with impaired endothelium dependent CFVR (aorta: 43.9 +/- 3.7 vs CS: 52.8 +/- 5.6, P = 0.05), suggesting transcardiac nitric oxide production. In addition, CS nitrite levels correlated with CS TNF-alpha levels in patients with impaired CFVR (r = 0.44, P = 0.003). Microvascular endothelium dependent CFVR is impaired in 26% of patients early after HTx. Activation of cytokines and the NO pathway seem to be involved in this vasomotor dysfunction The association between cardiac nitric oxide production and TNF-alpha in this group indicates a chronic high immunologic process, which may represent an early and important target for therapy and prevention of TxCAD.

Reduced myocardial cellular damage and lipid peroxidation in off-pump versus conventional coronary artery bypass grafting.

BACKGROUND: The development of new surgical devices and techniques allows off pump coronary artery bypass grafting (OPCAB) without the use of CPB and cardioplegia. This study tested whether OPCAB reduces myocardial cell damage, lipid peroxidation and systemic endothelin release when compared to conventional coronary artery bypass grafting. METHODS: Twenty-six patients were assigned to either the OPCAB procedure using a suction device and regular sternotomy (n = 13) or were treated conventionally using extracorporeal circulation, blood cardioplegia and hypothermic arrest (29-31 degrees C; n = 13). Troponin I and creatine kinase - MB were determined for cardiac specific cell damage. Myocardial and systemic malondialdhyde levels were measured to account for oxyradical mediated lipid peroxidation. Systemic big-endothelin levels were determined as a marker for endothelial cell activation. RESULTS: A significant reduction of the cardiac specific cell damage was observed in the OPCAB group vs. the CABG group over time in the absence of acute myocardial ischemia or infarction. In addition, systemic and myocardial lipid peroxidation as measured by the malondialdehyde (MDA) levels were lower in the OPCAB group when compared to CABG. Finally, plasma levels of big-Endothelin (big-ET) significantly rose in the CABG but not in the OPCAB group. CONCLUSIONS: The data of the present study indicate that OPCAB revascularization without the use of CPB and cardioplegic arrest reduces myocardial cell damage and lipid peroxidation. It is also associated with a reduced activation of the potent vasoconstrictor peptide endothelin. All of this may contribute to improved myocardial function and faster postoperative recovery from surgical revascularization procedures, particularly in critically ill patients.