Robotic totally endoscopic coronary artery bypass: program development and learning curve issues.

BACKGROUND: The introduction of new procedures in heart surgery is a critical phase that includes learning curves and the risk of increased mortality or morbidity. Totally endoscopic coronary artery bypass grafting using robotic techniques represents such an innovative procedure. The aim of this report is to demonstrate the safe introduction of totally endoscopic coronary artery bypass grafting using a stepwise and modular approach. METHODS: From June 2001 until December 2002, 50 procedures were performed using the da Vinci telemanipulator system. After baseline training the following procedure modules were carried out in a stepwise manner: robotically assisted endoscopic left internal thoracic artery harvesting and completion of the procedure as conventional coronary artery bypass grafting, minimally invasive direct coronary artery bypass, or off-pump coronary artery bypass (n = 19), robotically assisted suturing of left internal thoracic artery to left anterior descending anastomoses during conventional coronary artery bypass grafting (n = 15), totally endoscopic coronary artery bypass grafting on the arrested heart using remote access perfusion and aortic endocclusion coronary bypass grafting (n = 15). One patient was excluded intraoperatively from a robotic procedure due to pleural adhesions. RESULTS: A significant learning curve was observed for left internal thoracic artery takedown time, y(min) = 181 - 39 x ln(x) (x = procedure number) (P <.001), and total operative time in totally endoscopic coronary artery bypass grafting, y(min) = 595 - 87 x ln(x) x = (procedure number) (P =.028). The conversion rate in totally endoscopic coronary artery bypass grafting was 2/15. Intensive care unit stay correlated significantly with total operative time (r =.427, P =.002). There was no hospital mortality. CONCLUSION: Totally endoscopic coronary artery bypass grafting can be safely implemented into a heart surgery program. Learning curves are steep for robotic left internal thoracic artery takedown and for performance of totally endoscopic coronary artery bypass grafting. Long operative times translate into prolonged intensive care unit stay in specific cases but not into increased mortality.

Diltiazem versus nitroglycerin for myocardial protection following coronary artery bypass grafting as assessed by dobutamine stress echocardiography.

BACKGROUND: Perioperative infusion of the calcium channel antagonist diltiazem reduces the occurrence and extent of postoperative myocardial ischemia. However, recent reports also mention nitroglycerin as the drug of choice to prevent conduit spasm after coronary bypass grafting. The diagnosis of myocardial ischemia in the perioperative setting is still problematic. Dobutamine stress echocardiography (DSE) is an established technique that combines inotropic stimulation with real-time myocardial imaging and delineates normal and abnormal regional contraction patterns. We assessed the perioperative anti-ischemic effects of diltiazem and nitroglycerin during hemodynamic stress using DSE. METHODS: 50 adult patients were included in a prospective randomized study. Diltiazem or nitroglycerin was used from the onset of extracorporeal circulation until 24 h postoperatively. Dobutamine stress echocardiography was performed in a stepwise fashion 2 to 3 h after elective coronary artery bypass grafting. RESULTS: In 42 of 49 patients, dobutamine stress echocardiography either reached a level of 40 micrograms/kg/min dobutamine or achieved the target heart rate. One patient improved in terms of segmental wall motion abnormalities and three patients developed new abnormalities without corresponding electrocardiographic changes. Analysis of ischemia-sensitive parameters showed lower creatine kinase MB (p = 0.032) and troponin I levels (p = 0.1) in the diltiazem group 24 h postoperatively. Heart rate was significantly lower in the diltiazem group (p = 0.0003). CONCLUSIONS: Under conditions of hemodynamic stress, DSE revealed no significant difference between diltiazem and nitroglycerin with regard to renewed ischemia.

Complete revascularization in coronary artery bypass grafting with and without cardiopulmonary bypass.

BACKGROUND: The feasibility of complete revascularization on the beating heart without cardiopulmonary bypass (CPB) as compared with the standard operation with CPB in elective low-risk patients with multivessel disease has not been clearly demonstrated in a prospective trial. METHODS: Eighty selected low-risk patients were enrolled. In preoperative study with coronary angiography, the decision was made whether complete revascularization without CPB could be performed. Patients were randomly assigned to receive CABG either with (n = 40) or without CPB (n = 40). Randomization criteria were age, sex, and left ventricular ejection fraction. Completeness of revascularization as well as short- and mid-term clinical outcome in a 13.4 +/- 6.5 month follow-up period were monitored. RESULTS: Twenty-six of 40 (65%) patients undergoing CABG without CPB underwent complete revascularization. In 5 of these patients (12.5%) suitable vessels were discarded for technical reasons and 9 patients (22.5%) were switched to CABG with CPB owing to the deeply intramyocardial course of target vessels (n = 5) or to hemodynamic instability (n = 4). In the group of patients operated on with CPB, 34 of 40 patients (85%) received complete revascularization. In 6 patients (15%) suitable vessels were discarded for technical reasons. Mean number of bypass grafts was 3.1 +/- 0.8 with CPB and 2.6 +/- 0.5 without CPB (p = 0.043). Clinical outcome and hospital stay were comparable in both groups. No patient died during the study period. No myocardial infarction was observed. Three patients undergoing CABG without CPB underwent successful PTCA 3 months after surgery. CONCLUSIONS: CABG without the use of CPB is effective for complete revascularization in the majority of selected low-risk patients. Nevertheless, it has to be stated that the rate of incomplete revascularization in this early series of CABG without CPB is higher, and compromises the basic principle of complete revascularization.

Does the Ross operation fulfil the objective performance criteria established for new prosthetic heart valves?

BACKGROUND AND AIM OF THE STUDY: Objective Performance Criteria (OPC) were established to compare a new heart valve prosthesis with fixed standards of linearized complication rates for morbid events: thromboembolism, thrombosis, hemorrhage, leakage and endocarditis. Although the pulmonary autograft operation provides optimal hemodynamic performances, the morbidity of both the autograft and homograft remain topics of controversy. METHODS: Valve-related morbid events and echocardiography in 109 patients who have undergone the Ross operation since 1991 were evaluated at annual follow up examination (mean 2.8 years; range: 1 month to 8 years). Linearized rates (number of events per 100 years patient exposure) were calculated to establish the safety and efficacy of this operation (288.7 years cumulative patient-years). RESULTS: Three patients died perioperatively (2.8%); two patients were reoperated due to autograft incompetence (1.8%, both valve repairs). No patient is currently on anticoagulation therapy, and no events of thromboembolism, valve thrombosis or bleeding were observed during follow up. Two patients had homograft endocarditis but were asymptomatic with moderate incompetence at the last follow up examination. There was no significant increase in aortic incompetence (AI) or pulmonary incompetence (PI) between discharge and follow up (AI, 0.4 +/- 0.5 versus 0.6 +/- 0.6; PI, 0.2 +/- 0.4 versus 0.4 +/- 0.6). In comparing the OPC (events per patient-year) for the Ross operation with those for tissue and mechanical valves, the results were: thromboembolism 0% (tissue 2.5%, mechanical 3%), valve thrombosis 0% (0.2% and 0.8%), all bleeding 0% (1.4% and 3.5%), major bleeding 0% (0.9% and 1.5%), all leakage 0.7% (1.2% and 1.2%), major leakage 0.7% (1.2% and 1.2%) and endocarditis 0.7% (1.2% and 1.2%). CONCLUSION: The pulmonary autograft procedure provides optimal hemodynamics and echocardiographic performance, and low valve-related complication rates; thus, the OPC for tissue and mechanical heart valve prostheses can be fulfilled by this technically demanding operation. These results confirm that the autograft is an ideal aortic valve replacement device.

Noninvasive monitoring of peak filling rate with acoustic quantification echocardiography accurately detects acute cardiac allograft rejection.

BACKGROUND: Acute cardiac allograft rejection is associated with early diastolic dysfunction. The development of chronic rejection is dependent on the frequency and severity of acute rejection episodes. Therefore, early diagnosis and therapy influence long-term survival significantly. For the first time, acoustic quantification, a new echocardiographic technology for on-line measurement of cardiac volumes and their changes, facilitates quantitative assessment of systolic and diastolic function noninvasively. METHODS: Since May 1996, all consecutive patients after cardiac transplantation (n = 94) underwent 475 endomyocardial biopsies and the same number of echocardiographic studies within 6 hours after biopsy before the histological results were available. RESULTS: Nineteen patients showed 23 episodes of acute rejection (ISHLT > or = 2). There was a significant decrease in left ventricular peak filling rate [PFR: end-diastolic volume (EDV)/ second) as a parameter of diastolic function during rejection (2.9 +/- 0.4, n = 23) as compared to PFR measured under nonrejection status (4.5 +/- 0.8; n = 452; p < 0.0001). Most importantly we found that in these 19 patients showing rejection, the PFR was normal in the last examination before rejection, but was significantly reduced during rejection (2.9 +/- 0.4 vs 4.5 +/- 0.7; n = 23, p < 0.0001). After successful rejection therapy, PFR again normalized in all patients, with the exception of 1 patient with steroid-refractory humoral rejection. We calculated sensitivity and specificity for several cutpoints for the event "first rejection" in 15 patients and plotted them in a receiver operating characteristic curve, showing that a PFR > or = 4.0 EDV/second is never associated with treatable rejection. A decrease of PFR of more than 18% from its prevalue of the last biopsy with no rejection increases the accuracy for the diagnosis of rejection significantly. CONCLUSIONS: We conclude that diastolic dysfunction during acute cardiac allograft rejection can be accurately detected by noninvasive measurement of peak filling rate with acoustic quantification echocardiography. Monitoring of this parameter provides reliable discrimination between treatable and nontreatable rejection.

Reversal of ventricular dilatation after correction of aortic incompetence: mechanical prosthesis compared with biological procedures.

BACKGROUND: The aim of the study was to compare early differences in reversal of LV dilatation between patients with mechanical prosthesis = group A (n = 51: Carbomedics = 40, Tekna/Edwards = 11) and biological procedures = group B (n = 75: pulmonary autograft = 36, aortic valve repair = 29, homograft = 10). METHODS: Since 1,990,126 consecutive patients younger than 50 years who had surgical correction of isolated aortic incompetence underwent echocardiographic examinations preoperatively, at discharge, and at one-year follow-up. Left-ventricular (LV) diameters were measured (LVEDD, LVESD) and matched to body surface area (LVESDI, LVEDDI and fractional shortening (FS) was calculated. Aortic peak flow velocities were assessed by Doppler technique and gradients were calculated. RESULTS: There were no significant differences preoperatively in aortic incompetence, NYHA classification, LVEDDI, LVESDI, and FS. In group B there was a significant decrease of LVESDI (p < 0.002) and LVEDDI (p < 0.001) but no change in FS at discharge. In group A a significant reduction of FS (p < 0.05) without any significant changes in LV size was observed. No patient died perioperatively or during the first year. At one-year follow-up (complete in 97.6% patients) there were no significant differences in LV diameters but group B had better ventricular function (p < 0.05) resulting in better NYHA classification (p < 0.05). Only group B had normal aortic valve gradients at discharge and at follow-up (A: 25.2 +/- 4.3 vs B: 10.2 +/- 2.4 mmHg). CONCLUSIONS: Normal aortic valve gradients in patients after aortic valve repair or allograft replacement for chronic aortic incompetence lead to early recovery from ventricular dilatation and significantly better ventricular function at discharge. One year postoperatively they had improved ventricular function and NYHA class in comparison with patients in whom a mechanical prosthesis was implanted.

[Functional results and long-term outcome after bilateral lung transplantation for pulmonary hypertension]. / Funktionelle Resultate und Langzeitergebnisse nach bilateraler Lungentransplantation bei pulmonaler Hypertonie.

Pulmonary hypertension (PH) signifies elevated blood pressure in the pulmonary circulation either due to clearly defined causes (cardiac, pulmonary-parenchymatous, systemic) or of idiopathic origin (primary PH, PPH). While conservative treatment is beneficial only for a small number of patients, lung transplantation represents a curative measure. The optimal form of transplantation [i.e. single lung (SLTX), bilateral lung (BLTX) or combined heart-lung transplantation (HLTX)] is still under discussion. This study is a retrospective analysis of 16 patients with different forms of PH who underwent BLTX from 1992 to 1996 in Vienna. Four patients had Eisenmenger's disease due to atrial septum defect, 3 had chronic thromboembolic PH and 9 had PPH. BLTX with cardiopulmonary bypass was the standard procedure in all patients. Acute retransplantation had to be performed in 3 patients. Mean pulmonary arterial pressure was reduced from 63 +/- 11 mmHg preoperatively to 23 +/- 5 mmHg on the second day postoperatively (p < 0.0001), while the cardiac index concomitantly improved from 2.1 +/- 0.5 to 3.9 +/- 1.2 l/min/m2 (p < 0.05). Echocardiography proved normalisation of right ventricular wall thickness and end-diastolic diameter within 12 months, while tricuspid insufficiency, present in all patients before transplantation, resolved completely. Perioperatively 4 patients (25%) died due to septic complications (n = 3) or therapy refractory rejection (n = 1). Follow-up of the remaining patients ranged from 6 to 51 months (mean 33 +/- 17). One patient died at 8 months due to fungal sepsis. Eleven patients (68%) are currently alive. Only 2 of them show functional signs of chronic allograft rejection (bronchiolitis obliterans syndrome). All patients are at present in NYHA functional class I or II. In conclusion, BLTX results in complete recovery of right ventricular function and morphology and offers good functional long-term results. Because SLTX correlates with a high incidence of reperfusion edema, and HLTX is seriously limited by the scarcity of donor organs, BLTX should be the method of choice for treating end stage PH.

Analysis of left ventricular function after emergency coronary artery bypass grafting for life-threatening ischaemia following primary revascularization.

OBJECTIVE: Severe ischemic injury in the first few hours following primary revascularization necessitates acute reoperation. To study the effect of emergency coronary artery bypass grafting, we followed 18 patients for up to 8 years, relating their changes of global and regional myocardial function during the acute event and after secondary revascularization to final outcome. METHODS: A total of 16 patients with coronary artery bypass grafting (CABG) and 2 PTCA were treated for coronary heart disease between 1989 and 1993 and experienced life-threatening ischemic events (94% cardiogenic shock, 39% ventricular fibrillation, 67% ischemic electrocardiograph (ECG) changes) within 2.3+/-1.6 h after primary revascularization. Reoperation was carried out 1.0+/-1.3 h after the occurrence of acute ischemia. Serial echoes were obtained during the acute event and after reoperation as well as during the follow-up period. RESULTS: Of the 18 patients, 8 are currently alive, 5 died within 30 days and 4 within the 1st year. There was one late death 5 years after surgery. Global and regional wall motion was evaluated using short axis views of transesophageal echoes taken during the acute event and after secondary revascularization, and compared with transthoracic echoes in long-term survivors up to 5 years after surgery. During the acute event left ventricular ejection fraction (LVEF) was reduced in 83% of the patients and improved significantly after reoperation (chi2 = 11.74, df= 2, P < 0.01). As to regional wall motion, 50% of the segments in non-revascularized areas remained abnormal. Regional wall motion after reoperation was significantly better in the surviving patients compared with patients dying in the post-operative course (chi2 = 6.23, df= 1, P < 0.05). The revascularization score ( > 75%) of abnormal contracting segments during the acute ischemic event was a significant determinant for long-term survival. CONCLUSION: We conclude that patient outcome is determined by the severity of regional wall motion abnormality during the acute ischemic event, the aggressiveness of the attempt to revascularize these perfusion territories and their improvement after revision. Long-term survival reflects, therefore, the extent of emergency revascularization and therefore the ability to identify ischemic perfusion territories for surgical strategy planning.

Increased pulmonary flow velocities in oversized homografts in patients after the Ross procedure.

OBJECTIVE: Between September 1991 and July 1996, 60 patients (mean age 29.8 +/- 9 years; range 5-57) underwent aortic root replacement with pulmonary autograft, a viable biologic and nondegenerating substitute. The pulmonary root was replaced with cryopreserved homografts from cardiac transplant recipients. The aim of this study was to evaluate differences in early valve function of viable and cryopreserved allografts. METHODS: All patients had Doppler echocardiographic examinations preoperatively, at discharge from hospital and 54 patients at 1 year follow-up. We measured aortic and pulmonary peak flow velocities with continuous and pulsed-wave Doppler, and graded aortic and pulmonary insufficiency (AI, PI) with color Doppler flow (grade 0-IV). Intraoperatively, the diameters of the pulmonary root and the pulmonary homograft were measured with standard valve probes and matched to body surface area. RESULTS: Pulmonary peak flow velocity (PVmax) increased significantly from preoperative 0.87 +/- 0.11 m/s to 1.30 +/- 0.34 m/s postoperatively (P < 0.001). The implanted homografts (mean 25.9 +/- 2.4 mm) were larger than their native pulmonary diameter (mean 23.3 +/- 1.8 mm) in all patients. Homograft size matched for body surface area (BSA) did not correlate with increased PVmax. There was a significant increase of PVmax at follow-up (FU) since discharge, also (1.83 +/- 0.53 m/s; P < 0.001). Pulsed-wave Doppler demonstrates that increase of PVmax is located directly at the homograft leaflets and not at the anastomoses. Aortic peak flow velocities (AVmax) were normal postoperatively and at FU (post = 1.35 +/- 0.35 m/s; FU = 1.17 +/- 0.27 m/s). There was no significant change in AI or PI since discharge (AI FU = 0.8 +/- 0.4; PI FU = 0.7 +/- 0.5). Eight patients with fever and symptoms diagnosed as post-pericardiotomy syndrome had significantly higher PVmax at FU (PVmax = 2.41 +/- 0.40 m/s; P < 0.02). CONCLUSIONS: The Ross procedure leads to normal AVmax but significant increase of PVmax even in oversized cryopreserved homografts immediately after surgery. Further increase of PVmax without changes in AVmax in the first year demonstrates that changes in flow velocities are valve related and not due to increase in cardiac output. Further investigations will be necessary to determine whether this observation is due to valve rejection or early leaflet degeneration and treatment with immunosuppressive therapy is warranted.