Artificial intelligence as a precision tool for predicting risk of in-hospital death after aortic valve replacement

Background/Introduction

The prediction of risk of in-hospital death associated with cardiac surgery still has important gaps. In this scenario, the computational tools and mathematical techniques, the pillars of artificial intelligence, can represent an effective solution to this problem.

Purpose

To develop an in-hospital death prediction model for isolated aortic valve replacement (AVR) based on an artificial intelligence constituted by an artificial neural network (ANN).

Methods

352 patients consecutively submitted to isolated AVR between 2010 and 2020 were included. Altogether, 30 baseline variables were evaluated. Initially, the Extra Tree Classifier machine learning algorithm was used to select the attributes with the highest association with death. With the application of the algorithm, it was possible to identify the 11 variables with the greatest weight associated with in-hospital death. After selecting the variables and dividing the dataset into training (70%) and testing (30%), a risk prediction model was structured through an ANN with multiple layers. The ReLU activation function was used in the hidden layers and the SoftMax activation function was used in the output layer. As an optimizing function of the ANN, the Nadam function was used. In addition, a thousand cycles of propagation and data return (Epochs) were performed to induce machine learning based on the cyclic adjustment of the weights of each of the independent variables included in the model. Accuracy assessments were performed using the ROC curve in the test dataset. The model was developed using the Python programming language.

Results

A predictive accuracy of 93,6% (AUC 0,936) was observed for the occurrence of in-hospital death in the test dataset to the ANN. When comparing the performance of traditional risk scores, also tested only in the test dataset, we found that the ANN-based model was significantly superior to the scores (EuroScore I = 84,0% (AUC 0,840); EuroScore II = 84,4% (AUC 0,844), STS Score = 74,0% (AUC 0,740). The area under the curve of the model based on the ANN was significantly higher when compared to the areas of the scores using the DeLong test (p<0.05). When applying the same model only to patients aged 75 and over, the results were as follows: ANN AUC 0,877; ES1 AUC 0,652; ES2 AUC 0,590; STS AUC 0,663 (p<0,05).

Conclusion

The application of artificial intelligence modelling is feasible for the creation of prediction models in the health area. In this study, the accuracy of the ANN was significantly higher than that of the other traditional risk scores in the general sample and for patients with more advanced age. These findings demonstrate the great potential that representative datasets have when accessed through artificial intelligence techniques. The demand for massive volumes of information is mitigated when well-structured datasets with extreme data quality is used.

Funding Acknowledgement

Type of funding sources: None.

Artificial intelligence as a precision tool for predicting risk of in-hospital death after coronary artery bypass graft surgery

Background/Introduction

The prediction of risk of in-hospital death associated with cardiac surgery still has important gaps. In this scenario, the computational tools and mathematical techniques that constitute data science and provide machine learning, pillars of artificial intelligence, can represent an effective solution to this problem.

Purpose

To develop an in-hospital death prediction model for isolated CABG based on an artificial intelligence constituted by an artificial neural network (ANN).

Methods

3,124 patients consecutively submitted to isolated CABG between 2010 and 2020 were included. Altogether, 30 baseline and operative variables were evaluated. Initially, the Extra Tree Classifier machine learning algorithm was used to select the attributes with the highest association with death. With the application of the algorithm, it was possible to identify the 13 variables with the greatest weight associated with hospital death. After selecting the variables and dividing the dataset into training (70%) and testing (30%), a risk prediction model was structured through an ANN with multiple layers. The ReLU activation function was used in the hidden layers and the SoftMax activation function was used in the output layer to extract the specific probability of death and survival. As an optimizing function of the ANN, the Nadam function was used. In addition, a thousand cycles of propagation and data return (Epochs) were performed to induce machine learning based on the cyclic adjustment of the weights of each of the independent variables included in the model. Accuracy assessments were performed using the ROC curve in the test dataset. The model was developed using the Python programming language.

Results

After consolidating machine learning based on the training dataset with 70% of the general sample, it was possible to observe that through the artificial intelligence technique, a predictive accuracy of 83.86% (AUC 0.8386) was obtained for the occurrence of in-hospital death in the test dataset. When comparing the performance of traditional risk scores, also tested only in the test dataset, we found that the ANN-based model was significantly superior to the scores (EuroScore I = 71.4% (AUC 0.714); EuroScore II = 71.9% (AUC 0.719), STS Score = 71.1% (AUC 0.714). The area under the curve of the model based on the ANN was significantly higher when compared to the areas of the scores using the DeLong test (p<0.05)

Conclusion

The application of artificial intelligence modelling is feasible for the creation of prediction models in the health area. In this study, the accuracy of the ANN was significantly higher than that of the other traditional risk scores. These findings demonstrate the great potential that representative datasets have when accessed through artificial intelligence techniques. The demand for massive volumes of information is mitigated when well-structured datasets with extreme data quality is used.

Funding Acknowledgement

Type of funding sources: None.

Impact of atrial fibrillation on in-hospital outcomes of coronary artery bypass graft surgery: an analysis by propensity score matching

Background/Introduction

Many patients referred for coronary artery bypass graft (CABG) surgery have persistent or permanent atrial fibrillation (AF). Despite the significant occurrence, the impact of this arrythmia on surgical outcomes remains uncertain.

Purpose

To assess the impact of persistent or permanent AF on post-CABG in-hospital outcomes.

Methods

A cohort of 3,124 patients undergoing to isolated CABG between 2010 and 2020 was evaluated. A propensity score pairing was applied, considering persistent or permanent AF as a dependent variable and another 19 baseline characteristics as independent variables in the regression model used to build the propensity score. Pairing was performed at a ratio of 3:1 – Group 1: 324 patients without persistent or permanent AF; Group 2: 108 patients with the documented diagnosis of persistent or permanent AF. The statistical plan also included normality analyses, descriptive and univariate analyses, binary logistic regression, ROC curves and DeLong test to compare de curves. The significance level adopted was 5%. The analyses were performed by the programming language Python.

Results

None of the baseline characteristics evaluated showed a significant difference between the groups, including the EuroScore II (Group 1: 1.54±1.45 vs Group 2: 1.49±1.59; p=0.990). Likewise, none of the analysed surgical characteristics showed a significant difference, indicating a very approximate pattern of complexity of the surgeries. The absence of differences demonstrated a high degree of homogeneity between the groups. The use of pairing by propensity score aimed to form two extremely similar study groups, which differed only in relation to the diagnosis of the arrhythmia under study. Among the outcomes evaluated, AMI (1.5 vs 6.5; p=0.013), MACCE (7.1% vs 14.8%; p=0.015) and death (1.5% vs 6.5%; p=0.013) had significantly higher incidences in Group 2, formed by patients with persistent or permanent AF. From the multivariate analysis, it can be identified that permanent AF was an independent risk predictor for the occurrence of in-hospital death (OR: 5.009; 95% CI 1.433–17.507; p=0.012). Finally, it was also possible to verify that the association of EuroScore II with persistent or permanent AF showed higher predictive accuracy than EuroScore II alone (ESII+FA = AUC 0.852 vs ESII alone = AUC 0.775, p<0,05).

Conclusion(s)

Patients with persistent or permanent AF had significantly higher incidences of AMI, MACCE and in-hospital death. Persistent or permanent AF was characterized as an independent predictor for the occurrence of death and the association with the EuroScore II resulted in a 9.9% increase in the predictive accuracy of the surgical risk score.

Funding Acknowledgement

Type of funding sources: None.

Preoperative anaemia is an independent predictor of 30-day mortality post-CABG and improves de predictive accuracy of EuroScore II

Background

The impact of preoperative anaemia on the results of cardiovascular surgery has already been demonstrated by some authors. Some of the studies observed worse surgical results in anaemic patients, however, in others, no difference was observed. In addition, the impact that the inclusion of anaemia or haemoglobin would have as a predictor in a risk model such as EuroScore II is not yet known.

Purpose

To evaluate the impact of preoperative anaemia on 30-day mortality post-CRM and compare the predictive accuracy of EuroScore II with and without the inclusion of haemoglobin levels in the model.

Methods

Single center cohort with 2168 patients consecutively included between January 2010 and December 2020. All procedures were performed with cardiopulmonary bypass. 32 baseline and operative characteristics were assessed. The primary outcomes were 30-day mortality and the EuroScore II predictive accuracy. Patients were stratified into two groups according to anaemia status. WHO Classification – haemoglobin: men <13 g/dL and women <12 g/dL. No Anaemia Group (1301–60.1%) – Anaemia Group (867–39,9%). Univariate analysis was performed to compare the characteristics of the groups, the occurrence of death in 30 days and to verify variables associated with mortality. Logistic regression analyses were used to assess predictors of mortality and generate a set of probabilities for assessing the predictive accuracy of EuroScore II with and without the addition of haemoglobin in the model. The probabilities generated through the regressions were analysed by ROC curves, which in turn were compared using the DeLong test. The level of significance was 5% and the statistical analysis was performed using Python 3.0.

Results

The anaemic patients were older and had higher prevalence of conditions, such as: diabetes, renal impairment, smoking, HF class III or IV, RBC transfusion and highest mean of EuroScore II (p<0.05 for all conditions). When comparing mortality in the groups, a significantly higher rate was observed in the anaemic group (2.2% vs 5.4%; p<0.001). In view of the heterogeneity of the groups, an adjusted logistic regression model was applied. The results of the multivariate model demonstrated that preoperative anaemia was an independent risk predictor for the occurrence of death in 30 days after CABG (B: 0.597; SE: 0.27; Wald: 5.2; OR: 1.82; 95% CI 1.09–3.04; p=0.022). In addition, we were able to verify that the addition of preoperative haemoglobin to EuroScore II resulted in a significantly higher predictive accuracy when compared to the predictive accuracy of the isolated score (AUCs: 0,732 vs 0.709; p=0.032).

Conclusions

Preoperative anaemia was an independent risk predictor for the occurrence of death in 30 days after CABG. We were also able to verify that the addition of the preoperative haemoglobin levels to EuroScore II resulted in a significantly higher predictive accuracy, improving the performance of the surgical risk model.

Funding Acknowledgement

Type of funding sources: None. Figure 1. Haemoglobin vs 30-day mortalityFigure 2. Predictive accuracies – EuroScore II

EuroScore II is the best predictive model for the off pump coronary artery bypass graft surgery

Background

Coronary artery bypass graft surgery (CABG) is the most common cardiac surgery performed in the world and a significant part of these surgeries are performed without cardiopulmonary bypass (off pump). Although none of the main surgical risk scores include pump use in their prediction model, the scores are widely used in risk stratification, including for patients who will be submitted to off pump CABG.

Purpose

To analyse and compare the predictive accuracy of EuroScore I, EuroScore II and STS Score for 30-day mortality after off pump CABG.

Methods

Single-centre cohort with 943 patients consecutively submitted to off pump CABG between January 2010 and December 2020. 31 baseline and operative variables were analysed. The primary outcome was the occurrence of death in the first 30 days after the surgery. Descriptive analysis, normality for quantitative data and univariate inference were performed to compare proportions and means between the survival group (n=930) and death group (n=13). Next, three logistic regression models were performed. Each of them had 30-day mortality as a dependent variable and one of the scores as an independent variable. The probabilities generated by the three models were saved and analysed by ROC curves. Thus, it was possible to assess the predictive accuracy of each of the scores. Finally, the values of the areas under the curves were compared using the DeLong test. The level of significance was 5% and the analysis was performed using the Python 3.0 programming language.

Results

The mean age of the general group was 63 years old and there was a predominance of male patients (68.4%). The means of the three evaluated risk scores were significantly higher in the Death group (p<0,05). This pattern confirmed the findings of higher prevalence of several comorbidities in the death group. The 30-day mortality rate was 1.37%. Through the analysis of regressions and the probabilities generated through them, it was possible to verify that the predictive accuracy of EuroScore II was significantly higher than that of the other two scores. While the predictive accuracy of EuroScore II was 77.3%, the accuracy of two other scores was in the range of 69% (AUC EsI: 0.697; AUC EsII: 0.773; AUC STS: 0.695; p=0.029).

Conclusion

EuroScore II seems to be the most adequate surgical risk score for the assessment of mortality risk of patients who will undergoing to off pump CABG. The score had a predictive accuracy of 77.3%, almost 8% more than the other two scores. Therefore, although EuroScore II does not include in its model the use of cardiopulmonary bypass, it has a satisfactory accuracy to be used in clinical-surgical practice. On the other hand, the EuroScore I and the STS Score showed predictive accuracy not adequate for this type of surgery.

Funding Acknowledgement

Type of funding sources: None. Predictive accuracies of risk scores

Results of on-pump and off-pump coronary artery bypass graft surgery in 30 days: an analysis by propensity score matching

Background

The results of coronary artery bypass graft surgery (CABG) performed with and without the support of cardiopulmonary bypass have already been widely discussed and studied, including through a few large randomized clinical trials. Despite the efforts, the findings of these studies still generate controversy and doubts about the outcomes achieved by the two techniques. One of the contested points is the heterogeneity of the degree of specialization in the off-pump technique in relation to the surgical groups that participated in the studies.

Purpose

To compare the results in 30 days of on-pump and off-pump CABG.

Methods

A single centre cohort with 1,767 patients undergoing isolated CABG was initially evaluated (January 2013 – December 2018). 397 patients undergoing off-pump CABG and 1,370 patients undergoing on-pump surgery were identified. To obtain two completely homogeneous study groups, a propensity score matching was applied. For this, a logistic regression model was built with the variable use of CPB support as dependent variable. In the group of independent variables, 14 baseline and operative characteristics were included. The probabilities generated for each patient were used as scores to establish the match. To establish a pair, it was necessary to have three squares after the comma, with the fourth decimal place being the tiebreaker criterion in the pairing. In this way it was possible to obtain 332 pairs (N=664). The paired groups, on and off-pump, were compared by descriptive and univariate analysis and later a logistic regression model was applied to identify possible risk predictors and to verify the impact of CPB support on 30-day mortality. The level of significance was 5% and the analysis was performed using Python 3.0.

Results

None of the 29 baseline and operative characteristics showed a significant difference between the groups, demonstrating a high degree of homogeneity obtained from the propensity score matching, which enabled a solid comparison between the incidences of outcomes in 30 days. None of the analysed outcomes showed any difference between the groups on and off-pump, including AMI, stroke, major reoperation and death (1.5% vs 2.4%; p=0.401). Through regression analysis it was possible to establish that the use of CPB was not an independent predictor of risk for the occurrence of death (p=0.246).

Conclusion

After matching by propensity score, patients who underwent surgery with and without CPB had similar incidences of 30-day mortality. In addition, it was possible to verify that the use of CPB was not an independent predictor of risk for the occurrence of death in 30 days.

Funding Acknowledgement

Type of funding sources: None. Propensity score adjustment by group30-day outcomes vs CABG technique

P4735Preoperative frailty is a predictor of worse in-hospital outcomes after coronary artery bypass graft surgery and improves the predictive accuracy of EUROSCORE I and II

Introduction

Although coronary artery bypass grafting (CABG) is the most widely performed cardiovascular procedure in the world and is the standard treatment for complex coronary artery disease, the risk prediction for the procedure has major gaps. In this context, preoperative frailty may have a relevant role in the prediction of surgical risk.

Purpose

Our goal was to evaluate the impact of frailty on in-hospital outcomes after CABG and verify if any other comorbidity enhances the effects of fragility.

Methods

Prospective cohort of patients submitted consecutively to isolated CABG between Jan/2013 and Dec/2017. Frailty was defined as any deficiency in the Katz Index. Of the 1508 patients, 126 (8.4%) were classified as frail. Baseline characteristics and outcomes were compared by univariate analysis. Multivariate regression models were applied for the adjusted analysis of outcomes. The predictive accuracy of the regression models were analyzed using ROC curves. The additional predictive accuracy of the frailty and other risk variables were evaluated by comparing the ROC curves with the DeLong test.

Results

The frail patients presented more advanced age, more comorbidities and the majority were female. Frailty was an independent predictor for in-hospital mortality (OR 5.55, p=0.002) and MACCE (OR 5.60, p=0.001). In addition, by means of an adjusted analysis, we identified that the frailty was associated with a longer time of hospitalization (B 4.61, 95% CI 2.12–7.10, p<0.001). We also identified that preoperative anemia was classified as an independent predictor for hospital mortality and MACCE and improved the effect of frailty on outcomes. In this way, we could verify that when associated with surgical risk scores, frailty and anemia significantly improved the predictive accuracy of EuroScore 1 and EuroScore 2 for in-hospital mortality.

Predictive accuracies

Conclusions

Frailty and preoperative anemia are independent predictors of hospital mortality and MACCE after CABG. Frailty was also a predictor of longer hospitalization time. The association of frailty and anemia with surgical risk scores resulted in a significant improvement in the predictive accuracy of the scores. Frailty screening by Katz Index improved the risk assessment for isolated CABG and, when associated with anemia, demonstrated that frail and anemic patients had worse surgical outcomes.

Acknowledgement/Funding

The development of the present study was funded entirely by the Institution itself.

Health-related quality of life and right ventricular function in the midterm follow-up assessment after tetralogy of fallot repair

BACKGROUND

Few data are available on quality of life after surgical repair of tetralogy of Fallot (ToF), and on its relationship to right ventricle function.

METHODS

Patients with at least 1 year of follow-up evaluation after surgery were studied. Right ventricle function was evaluated by the Doppler-derived myocardial performance index (MPI), and health-related quality of life (HRQL) was assessed by the Child Health Questionnaire, Parent Form-50. Findings were compared with those for an age- and sex-matched group of healthy children.

RESULTS

The study enrolled 35 successfully repaired ToF patients with 4.9 years (range, 3-7 years) of follow-up evaluation after surgery and 36 healthy children. The MPI demonstrated right ventricle dysfunction in patients compared with controls (0.34; range, 0.26-0.49 vs 0.2; range, 0.13-0.27; p < 0.01), although HRQL for the psychosocial domain was similar between patients and healthy children (summary score, 47.9; range, 45-52 vs 47.5; range, 44.5-50; p = 0.17). A trend for poorer physical area results was observed in patients (summary score, 44; range, 31-52 vs 48.5; range, 45.7-51.7; p = 0.06). Neither physical nor psychosocial summary scores for HRQL had any correlation with right ventricle MPI.

CONCLUSIONS

Right ventricle dysfunction is present in postoperative ToF patients. The psychosocial domain of HRQL is preserved after surgery. A trend for worse results was observed in the physical domain. The right ventricle function is not related to quality of life after surgical repair of ToF.

Off-pump coronary artery bypass grafting does not reduce lymphocyte activation

OBJECTIVE

In this study, we test the hypothesis that off-pump coronary bypass surgery might result in less lymphocyte activation than on-pump coronary surgery. We also study the behavior of lymphocyte activation markers during and after surgery.

BACKGROUND

Coronary artery bypass surgery is known to be associated with changes of inflammatory mediators, immune function, and early phase lymphocyte activation, which could cause postoperative lymphopenia and lymphocyte unresponsiveness.

METHODS

We studied lymphocyte activation response in 28 patients randomized to off-pump (n = 13) or on-pump (n = 15) coronary artery bypass surgery. Expression of CD25, CD26, CD69, and DR on T (CD3+) and B (CD19+) lymphocytes on peripheral blood was assessed through flow cytometry.

RESULTS

The response of T lymphocytes and their activation markers, as well as B lymphocytes and their activation markers, was similar after on- and off-pump surgery. Overall, T lymphocytes decreased to the lowest level 9 h after surgery and tended to increase later. For B lymphocytes, there was early reduction with increase on the 1st postoperative day. There was early activation of CD69+ and late activation of CD25+ on T lymphocytes. For B lymphocytes, there was early activation of CD69+ and late activation of DR+.

CONCLUSIONS

(1) Compared to on-pump cardiopulmonary bypass, off-pump surgery does not reduce lymphocyte activation. (2) Coronary bypass surgery causes the early activation of lymphocytes, as evidenced by the increased expression of lymphocyte activation markers.

Partial left ventriculectomy: overall and late results in 44 class IV patients with 4-year follow-up

BACKGROUND

This study reports long-term results of partial left ventriculectomy (PLV).

METHODS

Forty-four patients with dilated cardiomyopathy were operated on in a 4-year study. Echocardiograms, catheterization, and stress tests with oxygen consumption (VO2) were performed.

RESULTS

The survivors' preoperative ejection fractions of 22.1% +/- 4.9% improved to 30.9% +/- 9.4%, left ventricular (LV) end-diastolic diameter decreased from 79.4 +/- 9.3 mm to 61.9 +/- 8.2 mm, and maximum VO2 consumption improved from 8.8 +/- 3.9 mL/kg per minute to 15.8 +/- 6.1 mL/kg per minute at 22.6 months. These data also showed improvements in nonsurviving patients, according to the last evaluation before death. Seven of 12 survivors (58.3%) were in New York Heart Association (NYHA) I and II in December 1998. Twelve patients had elevated pulmonary vascular resistance (PVR) contraindicating heart transplant. In five patients the PVR returned to normal and one high-PVR patient was transplanted at the 16th postoperative month. Survival was 56.8%, 47.7%, 38.4%, and 35.9%, respectively, at 3, 6, 12, and 18 months, with a tendency to stabilize at 32.7% thereafter. Arrhythmias and heart failure were the main causes of death.

CONCLUSIONS

In spite of improvement of ventricular function and quality of life of the survivors, high mortality is a limiting factor. PLV can be indicated as a bridge to heart transplantation in high-PVR patients or if ventricular assist devices or donor hearts are not available.

Holt-Oram syndrome revisited. Two patients in the same family

Holt-Oram syndrome was first described in 1960 as an association of familial heart disease and musculoskeletal abnormalities. The most important findings include atrial septal defects, atrioventricular conduction abnormalities, vascular hypoplasia, and upper limb musculoskeletal deformities. We report two patients with this syndrome in the same family and discuss the variability of the musculoskeletal abnormalities and their association with the cardiac morphologic defects. Both patients in this study had associated eosinophilia, which has not been reported in the literature.

[Involvement of pulmonary function in patients treated with rotated chest muscle flap surgery for the treatment of sternal wound complications after heart surgery]

PURPOSE

To evaluate pulmonary function of patients submitted to muscle flap for treatment of mediastinitis.

METHODS

Fifteen patients operated with the muscle flap technique were compared with 26 consecutive patients submitted to heart surgery with extracorporeal circulation, that did not present wound complications. Both groups were evaluated for age, sex, body weight, height, surgery, forced vital capacity (FVC), forced expiratory volume in first second (FEV1) and the relation (FEV1/FVC) in absolute and percentual values, espirometry conclusions and clinical evidences of lung disease.

RESULTS

There was no statistical difference between preoperative and postoperative period for FVC (p = 0.98), FEV1 (p = 0.68) and FEV1/FVC (p = 0.30) in the group with no sternal complications. In the control group, the median of FVC was 3907 +/- 1053.25 and in the study group was 2818 +/- 766.86 in absolute values (p = 0.0015). The median of FEV1, in the control group, was 2995 +/- 855.68 and in the study group was 2232 +/- 617.68 in absolute values (p = 0.0046). There was statistical difference, between groups, in FVC (104.78 +/- 21.73 and 82.04 +/- 21.16) and FEV1 (99 +/- 22.67 and 79.04 +/- 19.17) in percentual (p = 0.0026 and 0.0067) values. There was no statistical difference for the ratio FEV1/FVC. The study group had five patients diagnosed as having restrictive ventilatory insufficiency by espirometry against none in the control group (p = 0.0031).

CONCLUSION

Patients with infectious complications of sternum and mediastinum, treated surgically with muscle flap rotation may present restrictive pulmonary insufficiency in moderate degree, that must be considered in this situation.

[Surgical myocardial revascularization in young patients]

PURPOSE

To determine early and late results of surgical myocardial revascularization (SMR) in young patients.

METHODS

We studied retrospectively 73 patients aging less than 40 years and submitted to SMR between 1975 and 1989. The method used was patient card review and thelephone contact with the patient or his physician.

RESULTS

Follow-up was obtained in all cases in a period of 2 to 185 (59.9 +/- 41.0) months. Of the coronary risk factors smoking was the most frequent. One vessel coronary artery disease was observed in 16 (21.9%) patients, 2 and 3 vessel coronary artery disease in 26 (35.6%) and 32 (43.8%) patients respectively. SMR was considered complete in 68 (93.2%) patients. An associated procedure was performed on 10 cases: Left ventricular aneurysm repair in 9 (12.3%) and mitral valve replacement in one (1.4%). Perioperative myocardial infarction occurred in 7 (9.5%) patients and one of them died (operative mortality: 1.4%). During follow-up, 6 (8.3%) patients died with an actuarial survival rate of 89.1% at 15 years. An event free survival rate of 68.3% was observed at 10 years. From 66 survivors, 53 (80.3%) were asymptomatic at late follow-up and 48 (72.7%) patients returned to work.

CONCLUSION

Surgical myocardial revascularization in young patients associated with medical treatment, has good early and late results with a high percentage of patients asymptomatic and reemployed at a late follow-up.

[Adequacy of of pacemakers responsive to the volume-minute ventilation rate in heart transplantation patients]

PURPOSE

To evaluate in the late post-operative period (PO) the chronotropic response to exercise of patients submitted to orthotopic cardiac transplantation (CT) and the implant of a cardiac pacemaker (PM).

METHODS

A rate response ventricular PM (VVI+R) which uses minute ventilation (MV) as a sensor was implanted in five patients in the early PO of CT due to chronotropic incompetence. The patients were 31 to 64 years old and the indication to implant of PM was low ventricular escape rhythm following atrial taquicardia/bradycardia (one case) or sinus bradycardia (4 cases). The study was performed by means of paired exercise tests using Naughton protocol in order to compare the heart rate in VVI (prefixed heart rate) and VVIR+MV (rate response) mode. The duration of the exercise was compared between the two modes of stimulation.

RESULTS

In VVI mode the heart rate was significantly lower than in VVIR+MV mode for comparable periods of exercise (101 +/- 12 ppm vs 132 +/- 4 ppm; p < 0.05); in VVIR+MV mode the patients had a prolonged time of exercise as compared to VVI mode (15 +/- 7 min vs 12 +/- 7 min; NS).

CONCLUSION

The MV rate response PM provided patients with satisfactory heart during exercise and may be an adequate option to patients submitted to CT who present chronotropic incompetence.

Side-to-side carotid-subclavian anastomosis for interrupted aortic arch

A simple technique is proposed for restoring aortic flow in an interrupted aortic arch simulating a type B interruption that does not require aortic cross-clamping, circulatory arrest, or the ligation of major aortic branches. Side-to-side anastomosis between the left carotid and subclavian arteries together with division of the ductus arteriosus and pulmonary artery banding proved effective for relieving aortic arch stricture in that location.

Late outcome of unsupported annuloplasty for rheumatic mitral regurgitation

OBJECTIVES

The aim of this study was to evaluate medium- and long-term (range 4 months to 17 years) clinical results in a series of patients treated surgically by unsupported mitral annuloplasty.

BACKGROUND

Mitral valve regurgitation has usually been treated by valve replacement or ring annuloplasty. A few series have reported plastic repair procedures without annular support or remodeling. Furthermore, in rheumatic lesions the results have been inferior to those in degenerative mitral insufficiency, and the majority of previous reports have provided information on short- or medium-term follow-up.

METHODS

One hundred fifty-four patients were operated on (55 male [36%] and 99 female [64%]). The mean age +/- SD was 36 +/- 16 years (range 5 to 73). Associated lesions comprised 47 aortic and 21 tricuspid valve lesions and 2 atrial septal defects. Patients with concomitant mitral stenosis were not included. Preoperative functional class was I or II in 19% and III or IV in 81%. The cardiothoracic ratio was 0.61 +/- 0.10. All patients underwent an unsupported mitral annuloplasty procedure in which the mural portion of the annulus was reduced by applying two buttressed mattress sutures at the commissures without compromising the width of the septal leaflet. When necessary, additional chordal procedures were performed. No patients received ring or posterior annular support.

RESULTS

The early mortality rate was 1.9% (three patients; one of the three died of myocardial failure and two of pulmonary thromboembolism). The late mortality rate was 5.8% (nine patients; three of the nine died of myocardial failure, one each of septicemia, pulmonary thromboembolism and sudden arrhythmic death and three of unknown causes). Twenty-eight patients (18.2%) were reoperated on because of mitral valve dysfunction and 2 (1.3%) because of prosthetic aortic valve dysfunction. A residual late systolic murmur was present in 48% of patients. Late complications were systemic thromboembolism in 5.8% (one third with an aortic valve prosthesis), infective endocarditis in 1.3% and pulmonary thromboembolism in 0.6%. Postoperative functional class was I or II in 84% and III or IV in 16%. Cardiothoracic ratio was 0.58 +/- 0.10. Actuarial probability of late survival was 79.5 +/- 5.3% at 10 years and 71.0 +/- 7.4% at 14 years. Event-free survival was 67.9 +/- 8.9% at 10 years and 56.1 +/- 11.7% at 14 years.

CONCLUSIONS

Rheumatic mitral regurgitation can be effectively treated by annuloplasty without prosthetic annular support, with late results comparable to those obtained with more complicated procedures. This observation is particularly important for treatment of children and young adult patients.

Surgical repair of ventricular aneurysms. Early results with Cooley's technique

Using bovine pericardium instead of Dacron for grafting, we performed ventricular endoaneurysmorrhaphy (Cooley's technique) in 13 patients with postmyocardial infarction left ventricular aneurysm. Twelve patients were men and 1 was a woman; their ages ranged from 38 to 67 years (mean, 51.2 +/- 11.4 years). Eight patients had large anterolateral aneurysms, 4 had apical aneurysms, and 1 had a false inferior aneurysm. Postoperatively, the mean cardiac index increased from 2.07 +/- 0.50 to 3.09 +/- 0.99 L/min/m2 (p < 0.05), with a mean percentage increase of 50.17% +/- 37.03%. No patient required postoperative mechanical circulatory assistance, and pharmacologic support could be withdrawn soon after surgery. All patients had uncomplicated recoveries and were asymptomatic upon discharge, at a mean time of 9.0 +/- 2.3 days after surgery. We conclude that ventricular endoaneurysmorrhaphy provides excellent initial results, and we believe, through subjective analysis of ventriculograms, that the use of bovine pericardium for grafting produces better functional results than does the use of Dacron.

[The use of a rate-responsive pacemaker after heart transplantation]

PURPOSE

The indications and the results of pacemaker implant following orthotopic cardiac transplantation.

METHODS

Four patients implanted a cardiac pacemaker (PM) in the early post-operative period (PO) of orthotopic cardiac transplantation (from 10th to 16th PO day). The patients were 33 to 55 year-old and the indications to PM were supraventricular arrhythmia (atrial fibrillation or flutter) associated with atrioventricular block in three, and complete atrioventricular block in one patient. Previous to PM implant, patients were submitted to endomyocardial biopsy, which was normal in two patients, evidenced mild rejection in one and moderate rejection in the remaining. A ventricular rate responsive pacemaker was implanted in all patients, with sensors responsive to muscular activity in one patient, and to minute ventilation in three.

RESULTS

One patient died in the 20th PO due to acute allograft rejection not controlled by immunosuppressive drugs. Three other patients had satisfactory evolution and the pacemakers were programmed during exercise testing, previous to hospital discharge. Recent evaluation revealed that these patients are in good clinical condition at the 6th, 14th and 24th PO months. Adequate pacemaker function was insured by exercise testing and ambulatory electrocardiographic recording.

CONCLUSION

A ventricular rate responsive pacemaker represented a satisfactory mode of pacing, in patients with severe bradycardia, following heart transplantation.

New needle for catheter introduction in left atrium

We describe a new needle for left atrial catheter introduction. It allows catheter introduction through the right superior pulmonary vein or through the interatrial septum. Used in 32 patients (adults and children), the device proved to be highly efficient, simple, and safe.

[Hospital risk factors in subclavian-pulmonary anastomosis with polytetrafluoroethylene graft]

PURPOSE

Identification of risk factors for mortality in subclavian-pulmonary anastomosis using polytetrafluorethylene (PTFE).

PATIENT AND METHODS

Immediate surgical results (30 days) were analyzed in 180 cyanotic patients consecutively operated on from september 1979 to march 1989.

RESULTS

The hospital mortality was 12.7% (23 patients) and age at surgery, low weight (less than 3 kg) and preoperative diagnosis were considered risk factors for mortality. Pulmonary artery diameter at echocardiography, date of surgery and diameter of the conduits were associated with increased risk, but this association lacked statistical significance. Sex and previous palliative surgery have not increased hospital mortality.

CONCLUSION

We believe that identification of risk factors to PTFE conduit implant plays an important role in the preoperative management of those patients in order to obtain better results in this life saving procedure.

[Modified Cooley technique for surgical repair of left ventricular aneurysms]

PURPOSE

To evaluate early postoperative results of modified Cooley's technique of ventricular endoaneurysmorrhaphy.

PATIENTS AND METHODS

Eight patients, seven males, with ages ranging 38.0 to 67.0 years (m = 51.2 +/- 11.4 years) and with postinfarction left ventricular aneurysms were submitted to surgical repair by a modified Cooley's technique of ventricular endoaneurysmorrhaphy.

RESULTS

No postoperative complication occurred and all patients were discharged from the hospital asymptomatic on a mean time of 9.0 +/- 2.3 days after surgery. The mean cardiac index increased from 2.1 +/- 0.5 to 3.3 +/- 1.1 l/min (p less than 0.05) with a mean percentual increase of 53.0%. No patient required mechanical circulatory assistance after surgery and the pharmacological support could be interrupted soon.

CONCLUSION

Ventricular endoaneurysmorrhaphy searchs to restore shape, contour and volume to the left ventricle and has shown excellent initial results.

Permanent form of junctional reciprocating tachycardia with only even-numbered beats

An analysis of the electrocardiogram of a patient with the permanent form of junctional reciprocating tachycardia is presented. The patient demonstrated near-incessant tachycardia, with a 1:1 atrioventricular relationship and a retrograde P wave (P') occurring closer to the succeeding QRS complexes (ie, with a P'R interval that is shorter than the RP' interval). Each tachycardia episode was characterized by alternating short and long cardiac cycles due to alternation of retrograde conduction time (RP' interval), retrograde Wenckebach periodicity, and an even number of ectopic P' waves. The authors propose that there is an accessory AV connection with decremental functional properties that arborizes into two atrial branches with different conduction times. The fast branch initially exhibits a 3:2 retrograde conduction block followed by a cycle length-dependent 2:1 retrograde conduction block, thereby permitting alternate use of the slow branch, which is the weakest component of the reciprocating process.

[Countercurrent aortography by contrast injection into a peripheral artery]

Countercurrent aortography performed through left brachial artery in 8 children, aging 27 days to 42 months. Systemic-pulmonary anastomosis was possible to be assessed in 3 out of 4 cases, even in one aging 42 months. Aortic coarctation could be evaluated in another 3 patients. In the last case with a clinical suspection of vascular ring, countercurrent aortography disclosed an anomalous right subclavian artery. We concluded that the procedure is safe and useful to assess some conditions involving thoracic aorta, even in older children.

Subaortic fibrous ridge and ventricular septal defect: role of septal malalignment

The purpose of this study was to test the hypothesis that the presence of a subaortic ridge associated with a ventricular septal defect (VSD) is related to a malaligned ventricular septum caused by anterior or posterior deviation of the infundibular septum with or without obstructive lesions of the aortic arch. Thirty-two of 295 patients in whom a diagnosis of VSD was made by two-dimensional echocardiography and who were studied from June 1983 to April 1985 presented with a subaortic shelf. Every patient (p less than .00001) had a malalignment type of defect; the defect was produced by anterior deviation of the outlet septum (without compromise of the right ventricular outflow tract) in 28 and by posterior deviation of the infundibular septum in four. The prevalence of a subaortic shelf in the malalignment VSD group was 82% (32/39). Among the 28 patients with a subaortic ridge and anterior deviation of the outlet septum only three had aortic coarctation, but all four patients with subaortic stenosis and posterior infundibular malalignment had obstructive lesions of the aortic arch--coarctation in three and interruption of the aortic arch in one (p less than .001). We conclude that a malalignment type of VSD may be a consistent feature in patients with VSD and associated discrete subaortic stenosis. We also noted a high prevalence of subaortic ridge in the presence of a malalignment VSD and therefore speculate that there may be a common morphogenesis for malalignment VSD, subaortic shelf, and obstructive lesions of the aortic arch.

A new technique for repair of aortic coarctation. Subclavian flap aortoplasty with preservation of arterial blood flow to the left arm

From February 1984 to March 1986, 28 patients underwent a new technique of coarctation repair. This technique consists of a complete mobilization of the left subclavian artery extended to the origin of its first branches. The aorta need not be extensively mobilized and the intercostal arteries are individually controlled with snares. After all the proper clamping, the left subclavian artery is detached from the aorta at its origin and is opened longitudinally on its posterior aspect. The anterior wall of the aorta is then incised, beginning with the opening at the origin of the left subclavian artery and extending distally to the descending aorta 12 to 15 mm past the coarctation. The coarctation membrane is excised and the ductus is ligated and divided. The opened left subclavian artery, now forming a flap, is pulled down and sutured to the edges of the aorta, widening the coarctation site and also preserving the blood flow to the left arm. The ages of the patients ranged from 2 months to 25 years (mean 4.24 +/- 4.9 years) and their weights ranged from 2.8 to 52 kg (mean: 14.8 +/- 10.0 kg). There were no hospital deaths and the mean follow-up was 9.6 months (+/- 4.9 months). Recatheterization of four patients from 4 to 12 months postoperatively showed adequate correction and strongly suggested normal growth of the aorta at the site of coarctation, as well as preservation of the blood flow through the left subclavian artery. Doppler measurements showed normal flow to the left arm and no gradients through the isthmic area. Our experience indicates that this technique is not only feasible but is the procedure of choice in most cases of discrete isthmic coarctation and in some cases of long narrowing of the isthmus in patients with a wide range of ages and weights.

Subannular aortic aneurysms in whites. Report of two cases and review of literature

Subannular aortic aneurysms are a rare entity occurring predominantly in young black men. Five white patients have been reported who underwent surgical correction, but long-term survival occurred in only two. We report two white men, 36 and 45 years old, who survived aortic valve replacement and direct suture of subannular aneurysms, with no symptoms at 29 and 42 postoperative months.

[Atrio-septostomy using a Rashkind catheter in complete transposition of the great arteries. Immediate and late results]

Seventy one patients with complete transposition of the great arteries (TGA) who underwent balloon atrial septostomy (BAS) were studied, with the purpose to evaluate its early and late results within the first year of life. Fifty four patients were male (76,1%) and 17 female (23,9%), aged 2 days to 11 months (mean = 2,3 +/- 0,3%), being 46,5% less than 1 month old. Increase in mean aortic oxygen saturation (Ox. Sat.) after BAS was highly significant (p less than 0,001), irrespective of age and morphological features of TGA. Analysis of the group of 55 patients who underwent only BAS during the first year of life showed: mean age in the 13 non-survivors was 3,3 +/- 0,2 months; increase in Ox.Sat. was highly significant in the 42 survivors and not significant in the 13 patients who died; mortality in children with and without patent ductus arteriosus was 23,1% and 23,8%, respectively. Death directly related do BAS occurred in 2 patients (2,8%), without other complications being observed. We conclude that BAS is an effective and low-risk procedure, even in neonates with poor clinical condition. Early response to BAS is predictive of survival in the first year of life.