[Postoperative pain after cardiac surgery: neurobiological basis and treatment]

INTRODUCTION

Despite the evolution of surgical techniques, pain continues to be one of the most frequent disorders in the postoperative period of cardiac surgery (CS), leading to the appearance of complications in the acute period and impairment of quality of life due to the appearance of chronic pain. In this narrative review, we aim to analyze the prognostic factors for the appearance of postoperative pain after CS, to locate and quantify the severity of neuropathic pain, and determine the most appropriate assessment methods in these patients.

DEVELOPMENT

Postoperative pain in CS is a complex pain, which associates neuropathic, somatic and visceral components. Its origin is multifactorial; factors depending on the patient, the preoperative symptoms and the type of intervention, as well as sequelae derived from the surgery itself, determine the variability in its manifestation. Multiple studies have tried to identify the risk factors for its development, but the quantification of pain is limited by the subjective perception of the patients.

CONCLUSIONS

Neurologists can play a relevant role in the differentiation of the different types of pain after CS, thanks to the understanding of its neurobiological bases, properly handling neuromodulators that control the neuropathic component of pain and collaborating in the indication of invasive techniques, necessary occasionally in the management of these patients.

Aortic valve surgery in octogenarians: Risk factors and long-term impact

BACKGROUND AND OBJECTIVES

To understand the risk factors and long-term impact and results of aortic valve surgery in patients over age 80.

PATIENTS AND METHODS

We consecutively evaluated 255 octogenarians who were operated on between 2000 and 2013 and referred for aortic valve disease (isolated or combined with coronary artery disease), which, even when associated with other diseases, was the primary cause of the patient's functional limitation.

RESULTS

The mortality rate decreased from 14.08% (2000-2004) to 7.7% (isolated valve surgery, 4.4%; with coronary bypass, 3.3%) (2010-2013). The independent risk factors associated with mortality were urgent surgery, combined procedures, peripheral vascular disease, a postsurgery hematocrit level <24% and the need for transfusion. More than 50% of the patients experienced a postoperative complication. Blood product transfusions were associated with renal and respiratory failure, and preoperative anemia was associated with an increased rate of myocardial infarction and stroke. Survival at 1, 3, 5 and 10 years was 79.5, 74.3, 63.6 and 30.5%, respectively, with 91.5% of patients in NYHA functional class I-II. Long-term survival was lower for cases of preoperative left ventricular dysfunction. The EuroSCORE I logistics score was not useful for our population as a predictor of mortality or of medium to long-term survival.

CONCLUSIONS

The morbidity and mortality of aortic valve surgery for patients over age 80 has decreased in recent years, although it remains higher when valve surgery is combined with coronary surgery. The presence of preoperative left ventricular dysfunction decreases long-term survival.

[Evaluation of the withdrawal of ACE inhibitors in coronary artery surgery]

During cardiac surgery, as a result of surgical aggression, myocardial ischaemia and cardiopulmonary bypass, the renin-angiotensin-aldosterone mechanism is intensely activated. Our aim is to document whether, in the case of patients undergoing chronic treatment with lisinopril, the non-withdrawal of this inhibitor's administration before cardiac surgery and the administering of a last dose on the day of the operation are associated with coronary haemodynamic alterations. A study was made of 18 patients submitted to myocardial revascularization under extracorporeal circulation and distributed in two groups: group A) without ACE inhibitorsplacebo, group B) with ACE inhibitors (Lisinopril). Coronary blood flow (CBF) was determined by inverted thermodilution via Baim's catheter. Coronary and metabolic haemodynamic values were calculated. Lisinopril had no significant influence on the CBF or on the other above-mentioned values. Therefore, it is not necessary to withdraw ACE inhibitors in cardiac surgery interventions.

Apoptotic cell death and genetic control in graft coronary artery disease in heart transplant

AIM

Apoptosis is a type of programmed cell death whereby, immunologic, genetic and biochemical mechanisms are involved in its control. On the other hand, graft coronary artery disease is the most important restrictive factor for the long-term survival of heart transplantation. The purpose of this study is to analyse both apoptotic cell lesions in transplanted patients that present coronary artery disease.

METHODS

From August 1984 until December 1996, 148 heart transplants were carried out in the Clínica Universitaria de Navarra. In 102 patients, annual coronary angiography was performed, reaching a diagnosis of coronary artery disease in 30 patients. Study of apoptotic cell death was done in the tissue of endomyocardial biopsies on all patients by means of the TUNEL technique. Procedures of immunohistochemistry with antibodies antic-myc, p53 and bcl-2 were carried out and results were compared with a control group of 30 patients with homogeneous characteristics.

RESULTS

All patients with coronary artery disease showed apoptotic cardiomyocytes, 13 patients to a mild degree, 14 to a moderate degree and 3 to a severe degree, while in the control group apoptosis was found only to a mild degree in 8 patients, obtaining a very significant statistical difference (p<0.0001). The expression of analysed oncoproteins was null in the 2 groups.

CONCLUSION

Myocardial apoptosis is a constant finding in transplanted patients with coronary artery disease. We have not seen any correlation between the apoptotic process and genetic mechanisms.

[Specific markers of myocardial injury in acute stroke]

INTRODUCTION

It is thought that any acute damage to the central nervous system and, more particularly, acute cerebrovascular disease (ACVD) can give rise to a myocardial lesion. Our aim is to apply the latest biochemical markers (troponin T, troponin I and myoglobin) to the study of this problem.

PATIENTS AND METHODS

We conducted a retrospective study of 42 patients who were consecutively admitted to hospital with ACVD. The pathological antecedents and the clinical and electrocardiographic variables were considered in each case. A single determination of CK, CK MB, myoglobin, troponin T and troponin I was performed for each patient.

RESULTS

The determination of the new biochemical markers was positive in a higher number of cases than CK and its MB fraction, or electrocardiographic alterations. This positivity, together with the troponin T and troponin I values correlate with mortality.

CONCLUSIONS

We present the first research work to be published in Spanish that studies the new biochemical markers of myocardial damage in ACVD. We urge researchers to carry out further analyses on more extensive series in order to determine the influence myocardial damage has on mortality and to establish suitable therapeutic measures. This will also allow us to find out whether a certain location or size of the lesion can give rise to a higher predisposition to this kind of damage

Neurological complications after cardiopulmonary bypass: An update

INTRODUCTION

Neurological complications are, at the present time, considered among the most important causes of morbidity and mortality after heart surgery. We evaluated their importance and risk factors.

PATIENTS AND METHODS

We retrospectively reviewed 2, 528 consecutive patients who underwent cardiopulmonary bypass in a single center. In each one, we attended to previous vascular risk factors, such as surgical and postoperative events. We considered four categories of neurologic outcome: (1) persistent neurological focal deficits, (2) stupor or coma, (3) temporary neurological focal deficits, and (4) seizures. We carried out univariant and multivariant statistical analysis, looking for predictors of adverse neurologic events.

RESULTS

Neurological complications occurred in 76 patients (3%); 36 of them (47%) had persistent neurological focal deficits, 18 (24%) stupor or coma, 18 (24%) temporary neurological focal deficits, and 27 (36%) seizures. Twenty-two patients with cerebral adverse outcomes died (29%), the overall mortality among the 2,528 cases being 5%. Predictors of risk were aortic aneurysm and aortic valve surgery, advanced age, female sex, and the use of intra-aortic balloon pump. A longer hospitalization time was noticed among patients with neurological side effects.

DISCUSSION

Neurological complications are common and serious after heart surgery, as we have noticed with this series, the largest up to now, according to our review of the literature. They increase perioperative mortality and hospitalization time. Neurological morbidity and risk factors in our study are similar to those previously published.

Hydatid cyst of the interventricular septum in a 3.5-year-old child

An asymptomatic cardiac cyst located in the interventricular septum was diagnosed in a 3.5-year-old child by echocardiographic findings. Surgical ablation was done and histopathologic analysis confirmed a hydatid cyst. The patient was discharged without symptoms.

[Neurological complications of aortic artery surgery]

INTRODUCTION

Improvement in cardiac surgery techniques has led to a considerable reduction in mortality following surgery of the aorta, dissection of the aorta and for aortic aneurysms. Although there are satisfactory vascular results following surgical repair, morbi-mortality related to neurological complications, both cerebral and spinal, is still very high. Repair of aortic lesions may lead to damage by two main mechanisms: ischemia secondary to prolonged obstruction of the aorta or to neurological lesions due to total circulatory arrest.

DEVELOPMENT

After description of the mechanisms leading to cerebral and spinal lesions and the risk factors involved, we discuss methods of vascular protection and other means of neuro-protection, both spinal and cerebral. Of the vascular techniques for spinal protection, the most useful ones are short-circuits, or active or passive shunts, and cardiopulmonary by-pass. Amongst the vascular techniques for cerebral protection we describe total circulatory arrest and methods of anterograde and retrograde cerebral perfusion, and when these may be used. As general measures for nervous system protection, we describe the use of hypothermia and drugs such as corticosteroids, free radical blockers, antagonists of the excitatory amino-acids etc.

CONCLUSIONS

In spite of the number of studies done, the extreme sensitivity of the nervous system to ischemia has meant that in few cases have encouraging results been seen. Neurological damage continues to be the main cause of morbi-mortality in patients with dissection or aneurysm of the aorta.

Intracardiac thrombus trapped in a patent foramen ovale

We describe a case of impending paradoxical embolism due to a thrombus trapped in a patent foramen ovale in a 22-year-old woman. Transthoracic and transesophageal echocardiography detected the thrombus. She was operated on and discharged asymptomatic.

[The etiology of neurological complications after cardiopulmonary bypass surgery]

INTRODUCTION

Cardiopulmonary bypass (CEC) in the surgical treatment of cardiac diseases may cause the appearance of neurological damage of an intensity which varies between minor neuropsychological disorders and global cerebral anoxia. There are two mechanisms for the production of these lesions: ischaemic and embolic. The mortality associated with this type of complication is low, but morbidity may be considerable. The neurological disorders derived from CEC may be classified according to the aetiology and clinical findings. In the first group are included: severe cerebral anoxia, embolic cerebro-vascular accidents, microvascular embolias, lesions of spinal vascularization and lesions of the peripheral nerves. In the second group are: encephalic focal lesions, convulsive crises, lesions of the extra-pyramidal system, alterations in the level of consciousness and neuropsychological disorders.

METHODS

Quantification of neuronal damage has been attempted by: monitoring cerebral blood flow and neurone metabolism, EEG and study of intra-operative evoked potentials, echography of the carotid, cardiac and ascending aorta, transcranial doppler, fluorescein-angiography and the study of biochemical markers of neuronal and glial damage. Different studies have identified a series of factors which potentiate the risk of neurological lesions following CEC. These are: age, severe carotid disease, aortic atherosclerosis and previous cerebro-vascular haemorrhage, amongst others. An attempt is made to reduce the incidence of neurological complications by: pre-operative evaluation of carotid bruits, hypothermia, careful surgical technique and the use of drugs with a neuroglial protector effect. None of these methods gives sufficiently effective protection to the central nervous system subjected to the changes involved in the use of CEC.

CONCLUSION

There are still many unknown aspects of neurone pathology in these circumstances, leaving a door open to investigation.

Role of epicardial pacing wire cultures in the diagnosis of poststernotomy mediastinitis

Mediastinitis after cardiac surgery is difficult to diagnose in many cases. The transitory epicardial pacing wires used after surgery are placed in the mediastinum, so the culture of these wires could be useful for the diagnosis of this disease. To test this hypothesis, we routinely cultured the epicardial pacing wires of 565 patients undergoing extracorporeal circulation. Wires were removed on the 7th to 9th postoperative day under sterile conditions and were cultured with routine techniques used for the culture of venous catheters. Mediastinitis developed in 16 patients, and Staphylococcus aureus was the most common pathogen (81.25%). We had 103 positive and 462 negative cultures. There were 458 true-negative, 12 true-positive, 91 false-positive and 4 false-negative results. For mediastinitis in general, epicardial pacing wire culture has a sensitivity of 75%, specificity of 83.4%, positive predictive value of 11.6%, and negative predictive value of 99.1%. For Staphylococcus aureus mediastinitis, epicardial pacing wire culture has a sensitivity of 84.6%, specificity of 95.8%, positive predictive value of 32.3%, and negative predictive value of 99.6%. We conclude that a sterile culture of the epicardial pacing wires strongly contradicts a diagnosis of postsurgical mediastinitis.

[Aortic valve replacement via ministernotomy]

Minimally invasive cardiac surgery is arising as an alternative technique in some cardiac operations. We present the first aortic valve replacement via ministernotomy. We describe in detail the technique of ministernotomy and the limitations that this new approach would have. We conclude with the advantages of minimally invasive cardiac surgery over conventional approach and review other techniques described in the literature.

[Thromboendarterectomy as a treatment for chronic pulmonary hypertension]

Chronic pulmonary hypertension is an extremely difficult disease to diagnose and is usually identified by the exclusion of other more recognized causes of enlargement in mean pulmonary arterial resistance. Up to now, treatments proposed for this disease, have not been very successful. Medical procedures are not a long term proper solution which leads the process to an irreversible point whose only solution should be a pulmonary transplantation. In recent years, study groups have established a surgical method, alternative to transplantation, which has been able to increase, with a decrease in mortality rates, a longer and a better quality of life for the patients affected by this disease: we are talking about pulmonary thromboendarterectomy.

[A method for the predictive estimation of the surgical risk in adult cardiac pathology]

INTRODUCTION

In order to test the efficiency of statistical predictive models, we compare the results of a standard method (Parsonnet) with the model created through the data of our population.

MATERIAL AND METHODS

We used the chi 2 univariate model, lineal and logistic regression with the data of the whole population receiving cardiac surgical procedure from January 1, 1990 to December 31, 1993 (total 1626 patients). The population was divided into a control group (1100 cases, 68%) and a study group (526 cases, 32%). The coefficients of the control group were used to estimate the results in the study group.

RESULTS

Univariate model p value. Significant (p < 0.001) for emergency, age, pulmonary hypertension, left ventricular failure, preoperative use of intra-aortic balloon pump; p < 0.05 mitral valve disease, aortic aneurysm and reoperation. No significance (p < 0.01) was found for gender, aortic or tricuspid disease, percutaneous transluminal coronary angioplasty, unstable or postinfarction angina, transplant, left main or vessel disease number, and mitral, tricuspid or aortic procedure. MULTIVARIATE MODEL: Emergency, pulmonary hypertension, age, left ventricular dysfunction and aortic aneurysm. We estimated a 5.2%, 5.2% and 11.4% mortality with linear, logistic and Parsonnet method respectively with a real group mortality of 6.5%. The average error of the observed and predicted mortality after risk stratification was 5.7%, 6% and 12%.

CONCLUSION

A model for risk prediction based on the data of the own institution is more accurate for that population than a model created for comparison between institutions, because the former takes account of the center and population peculiarities.