Experiencia de 36 años con marcapasos implantables: un análisis histórico / A 36 year experience with implantable pacemakers

Background: The implantation of pacemakers improves cardiac function and quality of life, in particular with dual chamber DDD and DDDR modes. Aim: To evaluate our clinical experience and results on pacemaker implantation, from 1963 to 1998. Material and methods: Computerized data collected from 2,445 consecutive paced patients was reviewed. A total of 3,554 operative procedures were performed, including 412 procedures for complications and 697 pacemaker replacement. Patient survival was determined from clinical records, inquiry to pacemaker manufacturers and death certificates from Servicio de Registro Civil e Identificaci-n de Chile (Chilean Civil and Identification Registry). Results: Use of dual chamber (DDD and DDDR) pacemakers increased progressively up to 74 percent from 1988 to 1998. Complication rate was 42 percent in the 1963-1976 study period, it decreased to 10.6 percent in the 1977-1987 study period, and to 5.6 percent by 1988-1998. Only two patients died during surgery in the study period (0.08 percent). In the 1977-1987 period, pacemakers lasted 10.6 years. Survival rates were 52 percent at ten years, 33 percent at 15 years, and 21 percent at 20 years, with a median survival of 11.7 years, and 7.24 years in patients over 80 years old. Conclusions: Transvenous permanent pacing can be accomplished today with a low complication rate, mainly due to better technology and surgical procedures

Endarterectomía carotídea bajo anestesia regional: experiencia inicial / Carotid endarterectomy under regional anesthesia: initial experience

Background: Endarterectomy is the treatment of choice for internal carotid artery critical stenosis. Some authors have proposed that the use of regional anesthesia has advantages over general anesthesia. Aim: To report our initial experience with carotid endarterectomy under regional anesthesia. Patients and methods: Between 1998 and 1999, patients with critical carotid artery stenosis, asymptomatic or with transient and recovered symptoms, were selected. A C2, C3, C4 root deep cervical block and superficial block was performed, using a mixture of lidocaine and bupivacaine. A carotid endarterectomy with patch and without routine shunt insertion, with standard and neurological monitoring, was performed. Results: During the study period, 94 carotid endarterectomies were done, 22 under regional anesthesia in 21 patients (12 male, age range 58-90 years old). Ninety five percent had hypertension, 52 percent smoked and 38 percent had renal dysfunction. One patient was converted to general anesthesia. Seventeen patients were discharged within 48 hours of the procedure and the rest, within 72 hours. There was no mortality or complications. Conclusions: Endarterectomy under regional anesthesia is less invasive, has excellent results and is well accepted by patients

Opioides y sistema inmune / Opioids and the immune system

The immune response is partly regulated by the nervous system, that involves endogenous opioids, stimulating or depressing immune responses. Opioids modulate immune response by indirect and direct mechanisms. Indirect modulation occurs when the activation of opioid receptors within the nervous system modifies the activity of neuroendocrine axes or neurotransmission pathways. Direct modulation results from the effects of opioids on immune system cells. This requires the expression of membrane opioid receptors in these cells. Immunomodulating effects of morphine would be a result of the integration of indirect and direct effects. In animal models, morphine transiently depresses cellular and humoral immunity. In humans, morphine has similar effects; however, the real impact of morphine administration on the immune response in clinical situations in not yet known

Cirugía coronaria: veinte años de seguimiento / Results of coronary surgery: a 20 years experience

Background: Since the first surgical coronary revascularization done in Chile in 1971, 5000 such procedures bave been performed. Aim: To assess the long term results of coronary revascularization surgery in our institution and to identify prognostic factors. Patients and methods: Five groups of 100 patients each, composed by the first consecutive patients subjected exclusively to coronary bypass surgery in the years 1975, 1980, 1985, 1990 and 1995 were retrospectively studied. Results: Mean age of Patients increased from a median of 52 years old in 1975 to 62 yean old in 1995. No changes in the frequency of diabetes, hypertension, high serum cholesterol or prvious mycardial infarction were observed. There was an increase in the Proportion of patients with a recent (< 30 days) infarction that were operated along time. Seventy percent of patients had triple vessel disease or LMT and this proportion did not change. The number of grafts per patients increased form 1.9 to 3.4 and the use of arterial conduits from 0.18 to 0.81. Perioperative mortality remained constant and was 1.6 percent. Follow up information was obtained for 93 percent of 492 survivors. Actuarial survival at 5, 10, 15 and 20 years was 93ñ1, 82ñ2, 62ñ3 and 41ñ4 percent respectively. Ninety eight ñO.7, 89ñ2, 73ñ4 and 65ñ5 percent of patients remained free of a new myocardial infarction in the same lapses, respectively. Ninety seven ñl, 94ñ2, 76ñ4 and 47ñ7 percent of patients remained free of a new operation. Stepwise logistical regression analysis identified as bad Prognostic factors, in decreasing order: cardiac failure, diabetes, smoking, hypercholesterolemia and age at the moment of operation. Conclusions: Coronary artery bypass surgery provides good and long lasting clinical improvement. The prognosis of patients is influenced by the presence of cardiac failure, some well known coronary risk factors and age at the moment of operation

Revascularización miocárdida con una y dos arterias mamarias: resultados clínicos y seguimiento alejado / Myocardialrevascularization with 1 or 2 mammary arteries: clinical results and long term follow up

Patients and methods: One hundred and eight randomly selected patients who received one mammary artery for myocardial revascularization and 108 patients, matched for prognostic factors, who received two mammary arteries were studied. These patients were followed for a mean of 4 years (range 1 to 12 years). Operative complications, hospital mortality and long term probability of being free of disease were compared in both groups. Results: Operative mortality was similar in both groups (0,9 percent). Patients that received two mammary arteries had a higher frequency of operative wound complications. Long term survival was 84 per cente in patients who received one and 83 per cente in patients who received two mammary arteries. The probabilities of being free of myocardial infarction (92 and 82 percent respectively) and angina (94 and 86 percent respectively) were lower in the later group. Conclusions: Patients who received two mammary arteries had a higher probability of a long term disease free survival than patients who received one mammary artery

Aneurisma aórtico abdominal: evolución de la morbimortalidad de la cirugía electiva durante 20 años / Abdominal aortic aneurysm: morbimortality evolution of elective surgery during 20 years

Abdominal aortic aneurysms (AAA) usually undergo progressive dilatation and eventually may rupture,complication that caries a high mortality rate. If certain clinical conditions, like operative risk and aortic diameter are met, all patients should be considered for surgical repair. Analysis of our results with the surgical treatment of asymptomatic AAA prompted this stydy. Our of 479 consecutive patients operated because of AAA between 1976 and 1995, 378 (79 percent) were electively treated. Two decades: 1976-85 (101 patients) and 1986-95 (277 patients) were compared as far as associated medical conditions, surgical procedures, complications and mortality rate. There was no difference in age, sex, risk factors and aortic diameter. During the second decade we favoured the use of aortic tube grafts (53 percent vs 25 percent, p < 0.01) and epidural anesthesia (95 percent vs 35 percent, p < 0.01). During the last decade only 53.3 percent of the patients received blood transfusion, compared to 95.3 percent during the first period (p < 0.001). Operative mortality decreased from 5.94 percent to 0.72 percent (p < 0.05). Postoperative hospital stay diminished from 11.2 ñ 8.2 to 9.6 ñ 6.3 days (p < 0.05). These results compare favourable with those reported from other academic centers and support our therapeutic approach. Our contemporary surgical results serve as a reference for future clinical evaluation of endovascular procedures currently under investigation

Cirugía de revascularización miocárdica en los primeros 15 días de evolución del infarto / Miocardial revascularization surgery in the first 15 days of infarction evolution

Revascularization significantly improves early and late prognosis in acute myocardial infarction and has prompted substantial changes in therapeutic strategies. We report 140 patients aged 60.3 years old (123 male) operated within 15 days of sustaining an acute myocardial infarction, between january 1984 and december 1989. Coronary angiogram showed single vessel disease single vessel disease in 8 (6 percent), double vessel disease in 32 (23 percent), triple vessel disease in 85 (61 percent) and left main vessel disease in 13 (9 percent). Indications for surgery were ponstinfarction angina in 92 patients (66 percent), multiple severe coronary stenosis in 18 (13 percent), infarction of less than six hours from onset in 16 (11 percent), acute angioplasty failure in 7 (5 percent) and cardiogenic shock in 7 (5 percent). Thirty one patients were operated during the initial 24 h of infarction (16 with less than 6 h) 14 between the second and third day and 95 between the fourth and fifteenth day. Overall mortality was 4.3 percent (6/140). Among patients with failed angioplasty and cardiogenic shock, mortality was 23 percent (7/140), among patients with postinfarction angina this figure was 2.1 percent (2/92). Five years actuarial survival was 95 percent and the actuarial probability of being free of acute myocardial infarction, angioplasty or reoperation at five years was 99 and 100 percent respectively. It is concluded that early surgical revascularization in acute myocardial infarction is safe and has excellent long term results

Perfusión cerebral retrógrada durante paro circulatorio con hipotermia profunda: nueva técnica para la protección encefálica en cirugía de aorta ascendente y arco aórtico / Retrograde cerebral perfusion during circulatory arrest with deep hypothermia: new technique for encephal protection in aortic arch and ascendent aorta surgery

Between may 1993 and august 1994, 15 patients (10 men) with type A aortic dissection (9 acute) had a replacement of the ascending aorta and/or aortic arch with circulatory arrest with profound hypothermia and retrograde cerebral perfusion. Mean circulatory arrest time was 47.5 min (range 23 to 68 min). Three patients (20 percent) died in relation to postoperative bleeding. No patient had a new neurologic damage related to surgery. Ten patients were awake and oriented before 24 hours of the operation and another one before 48 hours; 4 patients required more than 48 hours to be completely awake and oriented. Two patients were operated on with a recent stroke. One of them recovered without sequelae before hospital discharge and the other one had a major regression of his brain damage. Two other patients had emergency surgery because of cardiac tamponade and cardiogenic shock. Both of them had a satisfactory recovery. Six patients presented azotemia but only 2 of them needed dyalisis. There was no case of Q wave infarction nor congestive heart failure in the perioperative period. Follow-up was 100 percent completed (12 patients) with a mean of 9.8 months (range 5 to 18 months). One patient died on the 10th postoperative month because of a late infectious process. Eight patients are in functional class I and 3 in II. Ten of them are back to their usual activities. Although retrograde cerebral perfusion is a new surgical technique, it seems to be a very valuable complement for brain protection in ascending aorta and/or aortic arch surgery with circulatory arrest with profound hypothermia