[Surgery of atrial fibrillation with intraoperative radiofrequency]

Radiofrequency ablation is successful in most supraventricular tachyarrhythmias and the first results in percutaneous applications in atrial fibrillation have been published. At present, all the surgical techniques for the treatment of atrial fibrillation use extensive atrial incisions. A case report is presented of a 67 year old woman with chronic atrial fibrillation and rheumatic mitral and tricuspid valve disease. At surgery, pulmonary vein isolation was performed using a continuous linear ablation around the pulmonary veins, instead of using extensive atrial incisions. Concomitantly, a mitral valve replacement and tricuspid valve annuloplasty were performed. Five months after surgery the patient remains with a stable sinus rhythm surgery and in functional class I (NYHA).

Cava endoluminal balloon occlusion as an adjunct technique to perform less invasive cardiopulmonary bypass procedures

OBJECTIVES

A cardiopulmonary bypass technique was developed with the aim of achieving a less invasive approach to right-sided lesions of the heart or to avoid extensive dissection in reoperations.

METHODS

Cavae endoluminal balloon occlusion (CEBO) was achieved with balloon catheters, introduced through cannulas inserted in the right jugular and one of the femoral veins. This procedure can be used in association with a standard femoral cardiopulmonary bypass or with the port-access technique.

RESULTS

Twenty-two patients were operated, through a right thoracotomy, for atrial septal defect (19) and tricuspid valve regurgitation associated with mitral valve pathology (3). There were two intra-operative complications, partially related with the development of this technique and lack of appropriate designed material. There was no mortality and a shorter and easier postoperative care was achieved in almost all patients.

CONCLUSIONS

The CEBO technique is an useful and safe adjunct to perform miniinvasive or complex reoperations on the right side of the heart.

When and how to report results of surgery on atrial fibrillation

OBJECTIVE

Several medical, interventional and surgical techniques are used to treat atrial fibrillation, aimed at different goals and having variable success rates. To be able to assess and compare all these techniques a methodology of study and a classification is proposed.

METHODS

We developed a five grade score, named the Santa Crus Score, based upon the post-operative atrial rhythm and the effective atrial contraction. Score 0 corresponds to a persistence of atrial fibrillation, the presence of a regular rhythm is grade 1, 2 or 3 if there is no atrial contraction; right atrial contraction; or bilateral atrial contraction, respectively. Score 4 corresponds to sinus rhythm and bilateral atrial contraction. Surgery for atrial fibrillation was performed on 51 patients since 1992. All patients but two had associated mitrial surgery. Three different maze techniques were performed on 17 patients and the pulmonary veins isolation procedure on 34 patients. Patients were reassessed at 1, 6, 12, 24 and 36 months.

RESULTS

After the maze I procedure atrial fibrillation eradication was achieved in 88% of patients but none scored 4. Three patients changed score during the first year. All maze III patients scored 0 initially and one changed to score 3 in the first year. Sixty percent of the maze IIIA patients scored 4, but one evolved to score 0 at 6 months. The pulmonary veins isolation technique eliminated atrial fibrillation in 71% of the patients initially, and in 60% after 1 year, and achieved a score of 4 in a third of the patients.

CONCLUSION

This classification considers the intermediate grades of success that can occur with absence of atrial fibrillation and is applicable to all forms of therapy.

Mechanisms underlying degeneration of cryopreserved vascular homografts

OBJECTIVE

To analyze the mechanism(s) underlying homograft degeneration, we designed an experimental model in which the behavior of cryopreserved autografts and homografts, as well as fresh autografts, implanted in the same animal was compared.

METHODS

A cryopreserved homograft was implanted in the aorta of 14 sheep. The excised aortic autologous segment was then subjected to cryopreservation, and 1 to 8 weeks later it was implanted 1 to 2 cm below the cryopreserved homograft. The intermediate segment of the native aorta, the fresh autograft, was dissected at this point. Animals were put to death at different times and the implanted segments were harvested together with a portion of native aorta. Histologic and immunohistochemical analyses, as well as cell viability assessments, were then performed on the explanted segments. Similar studies were also conducted on fragments of cryopreserved autografts and homografts before implantation.

RESULTS

With the exception of a partial loss of the endothelium, cryopreserved specimens retained cell viability and morphologic integrity before implantation. Explanted cryopreserved homografts showed profound changes affecting all strata, as well as a decline in cell viability. Lymphocyte infiltrates were found up to 12 months after implantation. Endothelium was always absent in cryopreserved homografts. However, a reendothelialization of the cryopreserved autografts was observed. After an initial period of neuronal degeneration, reenervation of the cryopreserved autograft segment occurred 6 to 12 months after the operation. Findings regarding the fresh autografts were similar to those of the cryopreserved autografts.

CONCLUSION

Our results suggest that the immunologic reaction rather than the cryopreservation process is responsible for the degenerative process occurring in cryopreserved homografts.

Operative risks of the maze procedure associated with mitral valve surgery

Twelve patients were operated on for mitral valve disease with concomitant chronic atrial fibrillation. Valve repair was performed in five patients and replacement in seven. Maze I and maze III procedures were applied in eight and four patients, respectively, and are compared. There was a regular rhythm in all maze I patients with a constant junctional rhythm in three and an alternating sinus and junctional rhythm in the remainder. In one case, part of the left atrium was in atrial fibrillation with the remaining atria in sinus rhythm. In the maze III group, one patient was always on a regular rhythm, two had episodes of atrial fibrillation and one was in atrial fibrillation with controlled ventricular rate. Echocardiography showed atrial contraction in two maze I patients, but systolic atrial flow across both atrioventricular valves could only be demonstrated in two patients in the maze III group.

What are the limits for the Ross operation?

The Ross operation is physiologically the best approach for aortic valve replacement. At the Hospital de Santa Cruz 22 consecutive pulmonary autograft operations have been performed in patients with a mean age of 49 (range 17-65) years. Six patients had mitral valve disease, two had aortic aneurysms and one had a ventricular septal defect. Subcoronary implantation of the autograft was performed in 20 patients. A partial inclusion aortic root replacement technique was used in one and the aortic root was replaced in another. There were no hospital or late deaths. Two patients required autograft replacement at 3 and 9 months postoperatively because of regurgitation. One of these cases was caused by an abnormality of the pulmonary valve and since then echocardiographic assessments of this valve have been performed routinely and have detected significant pulmonary incompetence in four patients who otherwise would have been operated on using the Ross procedure.

The large septal arteries in normal hearts, in aortic valve disease, and in tetralogy of Fallot

BACKGROUND

Several surgical techniques such as the Ross operation or total correction of tetralogy of Fallot require incisions of the upper ventricular septum. Very few reports on the anatomy of the septal arteries of the pathologic heart can be found in the literature. To get a more precise knowledge of the large septal arteries in pathologic hearts, we have compared the anatomy of normal hearts with that of hearts with aortic valve disease and of tetralogy of Fallot.

METHODS

Twenty-six normal heart specimens (group A), 11 with aortic valve disease (group B), and 4 with tetralogy of Fallot (group C) were dissected.

RESULTS

In groups B and C a single large septal artery was always found. The large septal artery had the orientation previously described for normal hearts. Still, its course in the lower border of the anterior extension of the septomarginal trabecula was deeper. The anterior extension of the septomarginal trabecula was 4 +/- 3 mm deep in group A, 6 +/- 2 mm in group B, and 3 mm in group C. The interventricular septum was much thicker in groups B and C than in group A.

CONCLUSIONS

The position of the large septal artery can be predicted from coronary angiography and from the morphology of the anterior extension of the septomarginal trabecula. Knowledge of its position can improve the safety of operations performed on the outflow of the interventricular septum.

Atrioventricular valve repair using externally adjustable flexible rings

Initial results obtained with a new flexible ring, adjustable from outside of the heart after interruption of extracorporeal circulation, are presented. Twenty-five rings have been inserted in 20 patients, 14 in the mitral position and 11 in the tricuspid position. In 8 of the 14 patients receiving mitral annuloplasty, other standard mitral valve repair techniques were used. Adjustment, assisted by intraoperative transesophageal color Doppler echocardiography, was done for 10 (71%) of the mitral rings and for 8 (73%) of the tricuspid rings. Residual mitral regurgitation disappeared or became minimal in 9 (90%) patients, and a mild regurgitation remained in 1. In all patients who received tricuspid rings regurgitation was abolished after the adjustment. There was no hospital or late mortality. After a maximum follow-up of 6 months results are comparable in the tricuspid and mitral positions and echocardiographic evaluation revealed stable competent valves in all patients but one, who underwent reoperation because of failure of a mitral valve chordae shortening procedure. The use of externally adjustable rings for the mitral and tricuspid valves is a safe alternative for atrioventricular valve annuloplasty and has the additional advantage of reducing postrepair regurgitation.

Autologous blood donation in cardiac patients

Despite the advantages of autologous blood transfusion, doubt still remains about its safety in cardiac patients. We report our experience with 439 cardiac patients who donated a total of 1692 units of blood before coronary, valvular, or congenital cardiac operations. During the collections, patients were continuously monitored with ECG, blood pressure, and heart rate. In 22 collections we observed vasovagal reactions, which represents an incidence of 1.3% of the total number of collections. The patients recovered quickly and only in 3 cases was volume replacement with saline needed. There were no other complications which could be related to the preoperative autologous donation program. We feel that, with careful selection of the patients and of the circumstances surrounding the collection of blood, autologous blood donation in cardiac patients is a safe and beneficial experience.

Histologic and genetic assessment of explanted allograft valves

A possible way of analyzing the immune response triggered by the allograft and the cellular viability is to compare immunocompetent and immunosuppressed patients, such as those having valve replacement and heart transplantation, respectively. These groups differ in immunosuppression therapy, preparation methods, valve hemodynamics. In the present study, we investigated polymerase chain reaction-amplified DNA flanking hypervariable (CA)n regions obtained from valve leaflets taken from patients having valve replacement or heart transplantation and performed a histologic analyses of the cells. In addition, we assessed an autograft valve to compare the hemodynamic effects on the cellular composition of the valve leaflet. We conclude that leaflet cellularity of the heart transplantation and autograft patients is superior to that of the valve replacement patients. These differences were consistent with the occurrence of an immune response in the valve replacement group, which was prevented or abrogated by immunosuppressive therapy administered to the heart transplantation group. However, it cannot be excluded that preparation procedures have a long-term effect on the extracellular matrix, leading to deterioration of cell adhesion and homing conditions.

The allograft valve in heart transplantation and valve replacement. Genetic assessment of the origin of the cells by means of deoxyribonucleic acid profiles

Assessment of the cellular origin of allograft valves is essential in comprehending their biologic behavior and in improving preparation methods. In this study we retrospectively analyzed 10 allografts obtained from patients who underwent valve replacement or heart transplantation. Histologic evaluation and deoxyribonucleic acid amplification by polymerase chain reaction technology with fluorescence labeled primers was performed on different parts of the valve leaflets. Automated analyses of the obtained amplimers showed in the heart transplantation group the presence of receptor cells interspersed with native donor cells in three cases. Preliminary results for the valve replacement group are inconclusive as yet.

Can the location of the large septal artery be predicted?

The aim of this study is to establish anatomical landmarks for the trajectory of the large septal artery. Thirty hearts were dissected, 20 of which had no cardiac pathology and the remaining with different cardiac conditions. One large septal artery was located in 27 of these hearts, two large septal arteries in 2 and three large septal arteries in 1. For all cases there existed one large septal artery in the lower border of the anterior limb of the septomarginal trabecula. When more than one large septal artery was encountered, the first was located within the subendocardial outflow tract of the left ventricle, the second was in the lower border of the anterior limb of the septomarginal trabecula and the third 1.5 cm below the second.

[Identification of a period of renal ischemic vulnerability studying the changes in the indicators of acute renal insufficiency after heart surgery with extracorporeal circulation]

We studied the pre operative status and the 1st, 4th, 12th and 24th hours of the post operative period after open heart surgery with cardiopulmonary bypass with a crystalloid solution containing 10 gr of mannitol. We considered acute renal failure (ARF) as being any increase in plasma creatinine values of 0.25 mg/dl for the first 24 hours and 0.5 mg/dl for periods longer than 24 hours. Six patients had transitory ARF (28.5%). The maximum value of plasma creatinine was 2.3 mg/dl and no patients required renal function substitution. There were no deaths. We used as ischemia ARF indicators the urinary flow rate, urine/plasma creatinine ratio, urine/plasma osmolality ratio, sodium fractional excretion and free water reabsorption. We also measured the urinary N-A-Glucosaminidase (NAG). We found that creatinine clearance reached its lowest in the first and fourth hours. Beyond the fourth hour we observed, the urinary flow rate reduce significantly, the urine/plasma creatinine and osmolality ratios reach values traditionally associated prerenal ARF, an increase main free water reabsorption and a decrease in sodium fractional excretion with a close relationship between the less than 1 value and the increase in plasma creatinine. There was a significant NAG increase in the 24 th hour. The evidence of a vulnerability period for renal ischemic lesions between the 4 th and 12 th hour suggests a second mannitol administration during the first four hours of the post operative period.

[Echo-Doppler in patients undergoing mitral commissurotomy. Comparison of open and closed commissurotomy]

OBJECTIVE

1. To evaluate with Echo-Doppler the medium/long term results of mitral commissurotomy. 2. To compare the results of open mitral commissurotomy to those of closed commissurotomy.

PATIENTS AND METHODS

The Echo 2D-Doppler study has been performed in 117 patients (104 females and 13 males), randomly selected among patients previously submitted to open (62 d.) or closed (55 d.) mitral commissurotomy, with greater than or equal to 12 months follow-up. Pulsed and continuous Doppler recordings were obtained in all 117 patients, and the following parameters were evaluated: Maximum Mitral Gradient (MG); mitral valvular area calculated by half-pressure time (MVA); presence of mitral regurgitation greater than or equal to grade 2 (MR); evaluation of systolic Pulmonary Artery pressure (PAP) by the gradient RV/RA + 14mmHg, in the patients with tricuspid insufficiency; acceleration time (ACT), ejection time (EJT) and the relation ACT/EJT in pulmonary artery. To compare the results of open commissurotomy, to those of closed commissurotomy, and in order to minimize the pre-operative differences between the patients submitted to each of these interventions, only the patients in the same NYHA functional class before surgery (class III), and in sinus rhythm have been selected. In this way two groups were compared: group A-24 patients with open commissurotomy and group F-37 patients with closed commissurotomy.

RESULTS

in the total of patients the results were: MG-9.8 +/- 4.2 mmHg; MVA-2.3 +/- 0.95 cm2; MR 16 pts. (13.7%); PAP obtained in 30 pts. (25.6%) -27.47 +/- 1.18 mmHg; the ACT, the EJT and the relation ACT/EJT in PA were respectively 115.63 +/- 34 ms, 309.9 +/- 38.5 ms, 0.37 +/- 0.1. The Doppler parameters obtained respectively in group A and in group F were: MG 8.96 +/- 4.5 mmHg and 10.38 +/- 3.82 mmHg (ns); MVA 2.62 +/- 1.01 cm2 and 2.08 +/- 0.84 cm2 (ns); MR 8.3% and 15.6% (ns) (Fig.3); the PAP have been calculated on 5(20.8%) patients in group A and on 10(27%) patients in group F and their respective values were 30.78 +/- 0.48 mmHg and 28.26 +/- 1.11 mmHg (ns); ACT 109.09 +/- 41.55 ms and 116.67 +/- 33.22 ms (ns); EJT 297.27 +/- 72.94 ms and 308.7 +/- 41.58 ms; ACT/EJT 0.35 +/- 0.12 and 0.38 +/- 0.10 (ns).

CONCLUSION

Both open and closed commissurotomy revealed to be good therapeutic alternatives to mitral stenosis with identical long term results as evaluated by Echo-Doppler. The results of percutaneous mitral valvuloplasty should be compared with these in the future.

Early surgical repair in traumatic rupture of the thoracic aorta (report of 9 cases and review of the current concepts)

Ten patients with rupture of the aortic isthmus due to blunt trauma were subjected to early surgical intervention with nine survivors (mortality 10%). A high degree of suspicion is necessary in order to make an early diagnosis. Left atrium (LA) to femoral artery (FA) bypass using systemic heparinization was used in all cases and bypass instituted before the aorta was prepared for clamping. Advantages of LA to FA bypass are as follows: (a) Technically easy; (b) Better control of patient during preparation of the aorta for clamping; (c) Provides the surgeon with more time to perform a safe operation.

Pulmonary embolectomy

Embolectomy was carried out in eight patients with pulmonary emboli. Angiographic diagnosis was obtained in six, and in two cases pulmonary angiography could not be done because of the very critical condition of the patients. In the latter two, diagnosis was made based only on clinical findings. Two patients died in the operating room (25 percent). Six patients were discharged in good condition. It is emphasized that pulmonary embolectomy should be done in cases of pulmonary emboli when a clinical status of shock is present (systolic blood pressure less than 80 mm of mercury and the patient in low cardiac output syndrome) and when there is no response to medical treatment regardless of the degree of obstruction in the pulmonary arterial tree.