An experimental sheep model used to develop an ablation procedure for chronic atrial fibrillation.

BACKGROUND: Atrial fibrillation is the most common form of serious arrhythmia in humans. The therapeutic options offered are medical, surgical, and interventional. The surgical approach is justified in cases of atrial fibrillation already subjected to cardiac surgery for an associated organic heart disease such as a valvular or ischemic disease. A minimally invasive surgical approach is needed to extend the possibility of surgical treatment to patients with lone atrial fibrillation and those who cannot be treated by interventional procedures. This study aimed to use sheep as an experimental model in developing a minimally invasive surgical procedure for chronic atrial fibrillation therapy in humans. METHODS: The investigation was conducted with 20 animals using a video-assisted thoracoscopic approach, in which a flexible microwave energy ablating probe was positioned on the epicardial surface encircling the pulmonary veins. RESULTS: In 10 of the 20 animals, it was possible to encircle the pulmonary veins using the thoracoscopic approach in less than 3 h without major complications. CONCLUSION: The epicardial ablation procedure using the thoracoscopic approach is feasible, safe, and reproducible.

Clinical histopathology and ultrastructural analysis of myocardium following microwave energy ablation.

OBJECTIVE: Due to weaknesses of conventional modes for treating atrial fibrillation (AF), surgical energy ablation methods and tools to cure AF have been under rapid development. One of these methods, microwave energy, is beginning to be applied clinically. The purpose of this study was to examine histology and ultrastructure of lesions produced by microwave energy in the myocardium. METHODS: Fifteen consecutive patients underwent surgical microwave energy ablation (Microwave Ablation System with FLEX 4 probe, AFx Inc., Fremont, CA) concomitant to a valve procedure. Epicardial ablation was carried out on the beating normothermic heart prior to performing the valve procedure. Two tissue specimens (1cm(2)) were obtained from each patient; one from the lesion site (right appendage) and the other from an adjacent, non-ablated site, which was used as control. Tissue samples were fixed and stained as appropriate for histological and ultrastructural analysis. RESULTS: All ablated samples revealed observable microscopic alteration, including loss of nuclei, foci of coagulative necrosis or induced irregular bands of contraction. Ultrastructurally, ablated cells demonstrated architectural disarray, loss of contractile filaments, mitochondrial swelling and focal interruption of plasma membrane. CONCLUSIONS: Histologic appearance of lesions created by epicardial microwave energy ablation was consistent over tissue samples, although acute findings demonstrated differences from cryoablation. In most of the cases, lesions were transmural, as was demonstrated by loss of cellular viability throughout the depth of tissue specimens.

Microwave ablation of atrial fibrillation in conjunction with treatment of early postoperative massive left atrial thrombosis.

Left atrial thrombosis is a rare complication of both atrial fibrillation and mitral valve surgery. A patient with a massive atrial thrombosis associated with symptoms of severe heart failure is presented. Restoration of rhythmical ventricular contraction and, ultimately, atrial contractility is of great benefit for providing relief from symptoms and for preventing thrombus recurrence. We present an approach to surgically treat atrial fibrillation using a new microwave energy source in a patient with left atrial thrombosis who requires a mitral valve prosthesis replacement.

Left atrial epicardial ablation associated to a Bentall procedure.

Aortic coarctation is quite a common congenital disease and very often associated with other cardiac malformations. A 21-year-old patient presented to our observation with aortic coarctation, aortic valve regurgitation on a dilated aortic root and chronic atrial fibrillation. We performed a two-step operation: the aortic coarctation was treated first and 1 month later a Bentall procedure associated to an epicardial ablation was performed. Since most of the ablation was performed before aortic cross clamping, the ischemic time was only slightly increased. At 3 months follow-up the patient is still on normal sinus rhythm.

How to determine the correct placement of the retrograde cardioplegia catheter.

Besides the surgeon's experience, there is no objective method to detect whether the retrograde cannula is inserted correctly before injecting the cardioplegia and measuring the coronary sinus pressure after the aorta cross-clamp. Repositioning of the retrograde cannula once extracorporeally is not always an easy maneuver and may include the risk of venous air suction. Manual detection of the cannula's position may jeopardize the stability of an ischemic heart (Ann Thorac Surg 50(6) (1990) 882; J Cardiothorac Vasc Anesth 5(6) (1991) 646; Ann Thorac Surg 52(4) (1991) 879). Determining the retrograde cannula position avoiding unnecessary prolongation of the ischemia would allow a better protection of the heart. To our knowledge such a method has not yet been published.

"Hybrid" percutaneous and surgical coronary revascularization: selection criteria from a single-center experience.

BACKGROUND: The association of minimally invasive direct coronary artery bypass (MIDCAB) to percutaneous transluminal coronary angioplasty (PTCA) of large arteries with focal lesions can be an alternative therapeutic method for patients with multivessel coronary artery disease. We reviewed our experience regarding 42 patients treated at our Institute. METHODS: MIDCAB and PTCA of the circumflex or right coronary arteries > 3 mm were performed in 42 patients from September 1997 to December 1999. RESULTS: One patient died after MIDCAB in the operating room because of rupture of the left anterior descending anastomosis. Postoperative angiography confirmed patency of the internal mammary artery (IMA) graft in 92.3% of cases: 3 early IMA graft failures occurred. The success rate for PTCA was 98%: in 1 case the wire just would not cross a chronically and totally occluded right coronary artery. The in-hospital morbidity was 12.2%: 2 patients required urgent sternotomy respectively for cardiac tamponade and coronary artery bypass grafting on cardiopulmonary bypass. One patient developed atheroembolism after PTCA with recurrence of symptoms, progressive multiorgan failure and death. Two patients required PTCA on the IMA anastomosis because of early failure of the arterial graft. At a medium follow-up of 535 days, all 40 survivors are in Canadian Cardiovascular Society class I. CONCLUSIONS: Hybrid revascularization appears to be an effective treatment for selected patients with multivessel coronary artery disease. The immediate success seems related to the learning curve for MIDCAB.

Port-access cardiac surgery: clinical experience with first 50 cases.

BACKGROUND: Minimally invasive cardiac surgery constitutes an expanding field for the treatment of many cardiac diseases. We analyze our experience with the first 50 patients operated upon using the port-access system. METHODS: From October 1999 to October 2000, 50 patients underwent cardiac operations with the port-access technique, for the correction of mitral and tricuspid disease, atrial septal defect closure, and removal of cardiac tumors. The mean age was 56.5 years. In 23 patients the mitral valve was repaired, in 14 cases a prosthetic replacement was performed, in 2 patients a paravalvular leak was resutured, 1 patient had a cardiac myxoma removed, and 1 patient had a correction of tricuspid regurgitation. In 9 cases an atrial septal defect closure was performed. RESULTS: One redo patient, with severe tricuspid regurgitation, needed conversion to sternotomy; in all the other cases the results of surgery were good and there were no surgical limitations. The mean cross-clamping time and bypass time were 53 +/- 19 and 77 +/- 27 min respectively. The mean in-hospital stay was 6 days. Re-exploration for bleeding was required in 7 patients (14%). Three patients (6%) presented with a postoperative neurological lesion; 2 recovered completely within 48 hours whereas 1 patient had permanent hemiplegia at discharge. There was one hospital death (an 81-year-old patient died of multiorgan failure on the thirteenth postoperative day). CONCLUSIONS: Minimally invasive port-access surgery is a reliable alternative to conventional surgery for the treatment of mitral and tricuspid disease, the removal of cardiac tumors, and the correction of atrial septal defects. It reduces trauma to the patient, provides a better cosmetic result and also allows for a faster recovery. Careful patient selection is important to avoid complications. Redo patients can be successfully treated and the risks of re-sternotomy avoided.

Limited posterior left atrial cryoablation in patients with chronic atrial fibrillation undergoing valvular heart sugery.

OBJECTIVES: We sought to evaluate whether a limited surgical cryoablation of the posterior region of the left atrium was safe and effective in the cure of atrial fibrillation (AF) in patients with associated valvular heart disease. BACKGROUND: Extensive surgical ablation of AF is a complex and risky procedure. The posterior region of the left atrium seems to be important in the initiation and maintenance of AF. METHODS: In 32 patients with chronic AF who underwent heart valve surgery, linear cryolesions connecting the four pulmonary veins and the posterior mitral annulus were performed. Eighteen patients with AF who underwent valvular surgery but refused cryoablation were considered as the control group. RESULTS: Sinus rhythm (SR) was restored in 25 (78%) of 32 patients immediately after the operation. The cryoablation procedure required 20 +/- 4 min. There were no intraoperative and perioperative complications. During the hospital period, one patient died of septicemia. Thirty-one patients reached a minimum of nine months of follow-up. Two deaths occurred but were unrelated to the procedure. Twenty (69%) of 29 patients remained in SR with cryoablation alone, and 26 (90%) of 29 patients with cryoablation, drugs and radiofrequency ablation. Three (10%) of 29 patients remained in chronic AF. Right and left atrial contractility was evident in 24 (92%) of 26 patients in SR. In control group, two deaths occurred, and SR was present in only four (25%) of 16 patients. CONCLUSIONS: Linear cryoablation with lesions connecting the four pulmonary veins and the mitral annulus is effective in restoration and maintenance of SR in patients with heart valve disease and chronic AF. Limited left atrial cryoablation may represent a valid alternative to the maze procedure, reducing myocardial ischemic time and risk of bleeding.

Left ventricular hemangioma.

Cardiac hemangiomas are rare, primary benign cardiac tumors. The authors report their experience of diagnosis and treatment of an hemangioma localized into the left ventricle. The tumor could be successfully resected and there is no recurrence at 1 year follow-up.

[Myocardial revascularization in patients with severely depressed left ventricular function]. / La rivascolarizzazione miocardica nei pazienti con funzione ventricolare sinistra severamente depressa.

BACKGROUND: Improvements in anesthetic and surgical management of patients with left ventricular dysfunction have resulted in a decline in perioperative mortality and morbidity. Nevertheless, coronary artery bypass grafting (CABG) in patients with left ventricular ejection fraction < or = 0.30 remains a surgical challenge. METHODS: Fifty-one patients with end-stage coronary artery disease and left ventricular ejection fraction between 16 and 30% underwent CABG. Mean age at operation was 66.1 +/- 7.85 years. Selection criteria included the clinical diagnosis of ischemic heart disease with angiographic demonstration of critical coronary artery obstructive lesions. Mean number of grafts per patient was 2.94 (range 1-5). Average duration of cardiopulmonary bypass was 74.5 +/- 22.4 min and mean aortic cross clamp time was 47.6 +/- 17 min. RESULTS: No operative and in-hospital deaths occurred. Eight patients (15.7%) had postoperative low cardiac output syndrome, requiring intraaortic balloon counterpulsation. There were two major neurological complications (3.9%). There were four late deaths (7.8%), due to recurrence of untreatable congestive heart failure. Left ventricular ejection fraction increased from a mean of 25.51 +/- 4.75% preoperatively to 31.35 +/- 9.9% postoperatively (p < 0.001). Improvement in NYHA functional class (preoperatively 2.98 +/- 0.79 vs 2.35 +/- 0.6 postoperatively, p < 0.001) was found in this group at follow-up. CONCLUSIONS: CABG leads to an excellent prognosis in high risk patients with ischemic heart disease and low left ventricular ejection fraction, improving their functional and clinical outcome and consequently their life expectancy.

Severe cutaneous cholesterol emboli syndrome after coronary angiography.

Cholesterol embolization syndrome is due to dislodgment of cholesterol crystals from the atherosclerotic plaques lining the walls of major arteries resulting in an occlusion of small arteries. We describe a case of severe cutaneous cholesterol emboli syndrome following repeat coronary angiography showing by our observation that this syndrome is often unrecognized or misdiagnosed and that a better evaluation of risks factors in patients undergoing invasive procedures could prevent this severe complication.

Comparison of response to serotonin of radial artery grafts and internal mammary grafts to native coronary arteries and the effect of diltiazem.

We studied the response of radial artery (RA) or left internal mammary artery grafts to the intraluminal infusion of serotonin in 22 consecutive patients 1 year after the operation, subsequently evaluating the effect of diltiazem in 9 patients. Serotonin causes a significant vasoconstriction of the RA grafts, but not of the left internal mammary artery grafts, whereas oral diltiazem treatment does not prevent the effect of the higher dose of serotonin on RA grafts.

"Hybrid" and combined percutaneous and surgical intervention to treat selected cardiac patients: a new strategy.

The term "hybrid revascularization" describes the combined use of minimally-invasive surgery without cardiopulmonary bypass and percutaneous coronary revascularization in selected cases. The theoretical advantage of a less invasive surgical intervention must be weighted against the need for additional percutaneous procedures, with their own risks and limitations. We describe our initial experience with hybrid revascularization at the Istituto Clinico Humanitas in Milan. From 7/97 to 10/98, twelve patients underwent hybrid revascularization or a combined percutaneous and surgical intervention. A "classic" hybrid approach, consisting of minimally-invasive direct coronary artery bypass to the left anterior descending coronary artery and angioplasty or stenting of arteries in the right coronary artery or circumflex territories, was used in nine patients. In three patients, myocardial revascularization could be completed with percutaneous procedures after bypass surgery without cardiopulmonary bypass (in two patients because of severe aortic calcification) or valve surgery in a patient with two previous bypass operations. In-hospital complications were observed in three patients. Two required urgent median sternotomy (one for impending cardiac tamponade, one for conversion to bypass on extra-corporeal circulation). One patient developed atheroembolism after percutaneous intervention: after hospital discharge, there was a recurrence of symptoms, clinical deterioration with renal failure and eventually death. At a mean follow-up of 152 +/- 91 days (range 17 to 283) after minimally-invasive surgery and 166 +/- 122 days (range 13 to 397) after angioplasty, all surviving patients are well and free of anginal symptoms. Closer collaboration between surgical and interventional operators may offer a novel approach to effective treatment of difficult patient subsets. However, our initial experience suggests that a cautious evaluation of possible risks and benefits must carefully be entertained in each patient who may be considered a candidate for hybrid revascularization or combined percutaneous and surgical intervention.

Relief of an early pulmonary pathway obstruction with stenting after modified Fontan operation in an adult.

The prognosis of Tricuspid Atresia, a rare congenital heart disease, has been changed by surgery. The criteria for Fontan operation have been well established in the literature and adult patients rarely fulfil these criteria; however, in very selected cases Fontan operation can be performed also in adults. A 33 year old woman with tricuspid atresia and previous palliation with classical right Glenn and with left modified Blalock-Taussing, underwent modified Fontan operation because increasing cyanosis and moderate exercise intolerance. Three weeks after operation the patient was readmitted with severe heart failure because of a tight obstruction at the anastomosis between right atrium and main-left pulmonary artery. The stenosis was treated with balloon and stenting achieving large pathway. Our experience confirms that after a modified Fontan, if cardiac failure occurs, an immediate full investigation have to be done.

The use of pulmonary allografts for aortic valve replacement. Short term results and comparative morphometric analysis of the aortic and pulmonary valves.

UNLABELLED: The satisfactory results of aortic valve replacement with pulmonary autograft and the limited availability of aortic allografts prompted us to use the pulmonary valve as an aortic valve substitute and to perform a morphometric analysis of the two valves in cadavers. CLINICAL STUDY: From March 1994 to March 1995 20 patients underwent an aortic valve replacement (AVR) with a pulmonary allograft (PA). Twelve patients were men, 8 women; age ranged from 15 to 58 years. In 4 cases the indication to AVR was an infective endocarditis which was acute in two patients. Functional class was NYHA II in 18 cases and NYHA III in 2 patients with active endocarditis. Left ventricular ejection fraction (LVEF%) was preserved in the majority of patients (mean LVEF=53% range 36% to 65%). End diastolic aortic valve diameters were measured by bidimensional echocardiography in parasternal long axis view and ranged from 18 mm to 29 mm. The diameters of the allografts implanted ranged from 19 mm to 27 mm. Donors age ranged from 19 years to 55 years. We tried to use the allograft from the youngest donor available. The surgical technique was the classic "Ross" coronary freehand implantation in 11 cases, a "Miniroot" implant in 8 instances and a "Miniroot" implant combined with a "Nicks" annular enlargment in 1 case. Aortic cross clamping ranged from 66 mm to 118 m (92m+/-10m). One patient died (5%) of infarction. In this patient the allograft was replaced with a mechanical valve because the echocardiography showed a rapidly increasing aortic regurgitation. At hospital discharge a slight aortic regurgitation was detected in 2 cases. In these two patients, whose annulus diameters were 26 mm and 28 mm respectively, we adopted a classic freehand technique of implantation. Mean postoperative transvalvular gradient was 4 mmHg+/-3 mmHg. The follow-up ranges from 45 days to 14 months (mean 8 months). The aortic regurgitation in the two cases remains stable and no new aortic regurgitations have been detected to date. No embolic or infective episodes occurred during the follow-up. ANATOMIC STUDY: Analysis was performed on 6 couples of valves obtained from cadevers without evidence of previous valvular disease. The normalized Free Edge (FE) dimensions and Leaflet Surfaces (LS) of the pulmonary valve (PV) proved to be larger than the corresponding aortic (AV) measurements (Free edge/Diameter: PV 1.25+/-0.2 vs AV 1.16+/-0.2 p<0.05; Annular Attachment/Diameter PV 1.9+/-0.1 vs AV 1.74+/-0.2 p=NS; Valve Surface/Leaflet Surface PV 0.97+/-0.2 vs AV 0.80+/-0.2 p=0.004) indicating that the PV has a larger coapting surface.

Use of the radial artery for myocardial revascularization.

BACKGROUND: The radial artery was first used as a coronary graft by Carpentier and associates in 1973 but, due to the disappointing results, it was abandoned. In 1992 its revival coincided with the widespread use of calcium-channel blockers in cardiovascular surgery, in the belief they could prevent spasm. METHODS: From January 1993 to October 1995 we operated on 109 patients for myocardial revascularization employing the radial artery with two different surgical techniques: in 95 patients (group 1) it was "pretreated" by opening its fascia after a gentle hydrostatic dilation and then anastomosed to the aorta; in 14 patients (group 2) it was branched to another conduit. We had two operative deaths (1.82%). RESULTS: At a mean interval of 532.42 days 105 patients are still alive, 2 (1.86%) having died of abdominal tumors. Fifty-six patients (52.33%) underwent angiography at a mean interval of 334.42 days: the patency of the radial artery was 88.88% in group 1 and 62.50% in group 2. Indications and contraindications are discussed. CONCLUSIONS: The radial artery is an easily manageable conduit whose early patency is very promising, although a longer follow-up is mandatory.

Safe removal of the radial artery for myocardial revascularization: a Doppler study to prevent ischemic complications to the hand.

Radial artery harvesting has recently been reintroduced for myocardial revascularization. Harvesting the radial artery may jeopardize the vascularization of the hand; cautious selection of candidates must therefore be pursued. The study involved 188 consecutive patients. We verified the patency of the upper limb's arteries and the adequacy of the ulnar supply by static and dynamic Doppler evaluations. The use of the radial artery was contraindicated in 14 cases (three for stenosis of the subclavian artery and 11 for inadequate collateralization). One hundred patients were operated on with the radial artery used as a graft; the remaining 74 patients had a different conduit placed. The vascularization of the hand was restudied within 10 days in all patients who underwent operation; in 63 patients, it was studied again at 1 year. The early Doppler examination showed significant increase in blood flow velocities in the ulnar artery, with a flow redistribution in the common digital palmar arteries (decreased in the first and increased in the second and the third). The late Doppler examination showed superimposable findings. No local ischemic complications were observed. We conclude that Doppler study is a useful tool in preoperative screening of candidates for radial artery harvesting for myocardial revascularization.

[Reintervention of myocardial revascularization by left thoracotomy in deep hypothermia. A clinical case]. / Reintervento di rivascolarizzazione miocardica per toracotomia sinistra in ipotermia profonda. Caso clinico.

Herewith we report a case of redo coronary-surgery which was approached through a left thoracotomy and in hypothermic arrest so as to avoid either a demanding dissection with its potential consequences over the functioning grafts and aortic cross-clamping thus making unnecessary any cardioplegia delivery. We describe the surgical procedure and analyze its advantages with respect to the usual median sternotomy approach.

Aortopulmonary window in the first year of life: report on 11 surgical cases.

From June, 1975, through April, 1986, 11 consecutive infants with aortopulmonary window were operated on at the Department of Cardiac Surgery, Ospedali Riuniti, Bergamo, Italy. The classic type of aortopulmonary window was present in 6 patients, whereas 4 patients had a ductus type of aortopulmonary window and 1 patient had a double aortopulmonary window, associated transposition of the great arteries, and ventricular septal defect. Operative technique included patch closure of the defect by means of cardiopulmonary bypass using various approaches: transaortic in 3, transpulmonary in 2, and transwindow in 2. The aortopulmonary window was ligated in 3 patients, in 2 of whom an incorrect diagnosis of patent ductus arteriosus was made at cardiac catheterization. Division and suture of the defect through a median sternotomy was performed in the remaining patient, who was moribund on admission. There was a single operative death. All survivors are in New York Heart Association Functional Class I at a mean interval of 6 1/2 years postoperatively.