Observation of Azimuth-Dependent Suppression of Hadron Pairs in Electron Scattering off Nuclei

We present the first measurement of dihadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the gibuu model, which suggests that hadrons form near the nuclear surface and undergo multiple scattering in nuclei.These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei.

Prognostic value of 13C-phenylalanine breath test on predicting survival in patients with chronic liver failure

AIM: To evaluate the prognostic value of percentage of ¹³C-phenylalanine oxidation (¹³C-PheOx) obtained by ¹³C-phenylalanine breath test (¹³C-PheBT) on the survival of patients with chronic liver failure.

METHODS: The hepatic function was determined by standard liver blood tests and the percentage of ¹³C-PheOx in 118 chronic liver failure patients. The follow-up period was of 64 mo. Survival analysis was performed by the Kaplan-Meier method and variables that were significant (P < 0.10) in univariate analysis and subsequently introduced in a multivariate analysis according to the hazard model proposed by Cox.

RESULTS: Forty-one patients died due to progressive liver failure during the follow-up period. The probability of survival at 12, 24, 36, 48 and 64 mo was 0.88, 0.78, 0.66, 0.57 and 0.19, respectively. Multivariate analysis demonstrated that Child-Pugh classes, age, creatinine and the percentage of ¹³C-PheOx (HR 0.338, 95% CI: 0.150-0.762, P = 0.009) were independent predictors of survival. When Child-Pugh classes were replaced by all the parameters of the score, only albumin, bilirubin, creatinine, age and the percentage of ¹³C-PheOx (HR 0.449, 95% CI: 0.206-0.979, P = 0.034) were found to be independent predictors of survival.

CONCLUSION: Percentage of ¹³C-PheOx obtained by ¹³C-PheBT is a strong predictor of survival in patients with chronic liver disease.

[Coronary reoperation: a 16 years retrospective analysis]

BACKGROUND

Coronary artery bypass grafting (CABG) reoperation is being performed with increasing frequency.

AIM

To assess the early and long term results of coronary reoperations in our institution and to identify prognostic factors.

PATIENTS AND METHODS

214 patients subjected to coronary reoperations between 1983 and 1999 were retrospectively studied.

RESULTS

Mean age was 64.2 years (range 42-79 years), 202 (94.4%) were male and 12 (5.6%) female. The mean interval between the operations was 125.7 months (range 6-252 months). 10 (4.6%) were emergency surgeries. Overall operative mortality was 5.6% (11 deaths) and in 5 patients (3.4%) a perioperative myocardial infarction was noted. Univariate analysis identified moderate or severe left ventricular failure (p = 0.048) as predictor of increased operative mortality, meanwhile age over 75 years (p = 0.02) and moderate or severe left ventricular failure (p = 0.01) were identified as predictors of increased in hospital mortality in the multivariate analysis. Follow up of in hospital survivors (mean interval 65 months, range 4 to 190 months) documented a 5 years survival rate of 82.9%, a 10 years survival rate of 73.1% and a 15 years survival rate of 53.4%. Moderate or severe left ventricular failure (p < 0.0001) and emergency surgeries (p = 0.007) were identified as factors influencing the late survival in the stepwise logistical regression analysis. Multivariate analysis identified left ventricular failure (p = 0.01) and peripheral vascular disease (p = 0.01) as predictors of decreased late survival.

CONCLUSIONS

Coronary reoperation has a low mortality in patients with a normal ventricular function and also has an excellent overall and disease free survival in the first 10 years of follow up. Left ventricular function is an independent risk factor increasing in hospital and late mortality.

[Obituary: Dr René Favaloro (1923-2000)]

René Favaloro MD, was born in La Plata, Argentina, in July 1923. He studied medicine in La Plata and made his cardiology residence in the Cleveland Clinic, where he developed coronary bypass surgery for the treatment of ischemic heart disease. At the present time, this surgical procedure is a well recognized therapy for coronary artery disease that has benefited millions of patients. Back in Argentina, he founded in 1992 the Institute of Cardiology and Cardiovascular Surgery that had an important research and teaching activity. Dr Favaloro wanted to be remembered as a teacher rather than as a surgeon, but he really was a great Master of Surgery in the Americas.

[Treatment of advanced heart failure by heart transplantation]

BACKGROUND

Heart transplantation currently provides the most effective treatment for advanced heart failure. However, medical therapy for this condition has also improved, heart donors are scarce and the cost of the procedure is high. Therefore the indications and management of these patients need reevaluation.

AIM

To analyze the results of 24 patients submitted to heart transplantation for end-stage heart failure needing repeated hospitalizations and i.v. inotropes for compensation.

PATIENTS AND METHODS

The group was comprised by 21 men and 3 women with a mean age of 36.8 years, mean left ventricular ejection fraction 19 +/- 4.5%, mean systolic pulmonary artery pressure 48 +/- 13 mmHg (24-70) and mean pulmonary vascular resistance 2.6 Wood Units (1-5). Fourteen patients (58%) had a previous median sternotomy. Immunosuppression did not include induction therapy and steroids were discontinued early.

RESULTS

Operative mortality was 4% at 30 days. Actuarial survival at one year was 90% and at 5 years 72%. Freedom from rejection at one year was 76% and at 5 years 50%. Freedom from infection was 70% at one year and 56.5% at five years. All patients with more than 3 months of follow-up were in functional class I.

CONCLUSIONS

These results justify the proposed modifications for transplantation protocols.

[Humoral rejection in heart transplantation. Report of 2 cases]

Heart transplantation is a therapeutic alternative for selected patients with refractory heart failure. Acute allograft rejection is one of the main causes of early death after transplantation. The cellular rejection is characterized by cellular infiltrates with or without myocyte necrosis. However, some patients develop left ventricular dysfunction due to rejection without evidence of cellular infiltration. In these patients, the rejection is mediated by antibodies and complement. Humoral rejection is a relative rare but potentially fatal form of acute allograft rejection. We report two patients with left ventricular dysfunction secondary to humoral rejection, shortly after cardiac transplantation. Both patients were treated with methylprednisolone, and azathioprine was substituted by cyclophosphamide. One patient underwent plasmapheresis. The clinical outcome was satisfactory and the left ventricular function returned to normal in both cases. The diagnostic and therapeutic strategies for the management of humoral rejection are reviewed.

[Neuropeptide Y contribution and the physiology of human sympathetic co-transmission. Studies in saphenous vein biopsies]

BACKGROUND

It is known that the sympathetic varicosities co-store and co-release norepinephrine (NE) together with adenosine S-triphosphate (ATP) and neuropeptide Y (NPY).

AIM

To describe the chemical characterization of stored and released NPY from the varicosities of sympathetic nerve terminals surrounding segments of the human saphenous vein, and the vasomotor activity of rings electrically depolarized or contracted by the exogenous application of the co-transmitters.

MATERIAL AND METHODS

Saphenous vein tissues were obtained from patients undergoing elective cardiac revascularization surgery.

RESULTS

The chromatographic profile of NPY extracted from biopsies is identical to a chemical standard of human NPY. Upon electrical depolarisation of the perivascular sympathetic nerve terminals, we demonstrated the release of NPY to the superfusion media, which did not exceed a 1% of its stored content. The release of the peptide is sensitive to guanethidine, and to extracellular calcium, suggesting that the mechanism of its release is exocytotic in nature. The electrically evoked release of NPY is dependent on the frequency and duration of the electrical pulses. Phenoxybenzamine reduces the electrically evoked release of NPY. Exogenous application of NE and ATP contract saphenous vein rings; the simultaneous application of NE plus ATP causes a synergic response, effect which is further potentiated by the joint co-application of 10 nM NPY.

CONCLUSIONS

Present results highlight the role of NPY as a sympathetic co-transmitter in the regulation of human vascular tone.

[Myocardial revascularization of the anterior descending artery with the classical technic of mammary anastomosis]

INTRODUCTION AND OBJECTIVES

To establish the results obtained with the classical technique of mammary anastomosis of the anterior descending artery.

MATERIALS AND METHODS

Between January 1982 and July 1997, 154 patients received an anastomosis of the left internal mammary artery to the left anterior descending coronary artery with use of the classical technique (sternotomy and extracorporeal circulation).

RESULTS

There was no operative mortality in our group, nor paraoperational myocardial infarction, nor cephalic vascular accidents. One (0.6%) patient had sternal wound infection, and another (0.6%) required another reoperation for postoperational bleeding. All (100%) were followed-up from 3-183 months (average 64. 4 months). Actuarial global survival at 5, 10 and 15 years was 95.6%+/-2.1; 92.1%+/-4 and 85.5+/- 7.5 respectively, and the actuarial probability of being free from cardiac death was 99%+/-0.9; 99% and 99%. The actuarial probability of being free from myocardial infarction was 99%+/-0.9; 99%+/-0.9 and 99%; and from angina was 95%+/-2.2; 86.9%+/-4.9 and 74.5%+/-12.2 at 5, 10 and 15 years.Finally, the actuarial probability of being free from reoperation was 99%+/-0.9; 99%; 99% and from angioplasty 96.9%+/-1.7; 91.4%+/-4.1; 91.4%+/-4.1 at 5, 10 and 15 years, respectively. The average hospital charges in the last 10% of the patients was U$ 6.200.

CONCLUSIONS

Revascularization of the left anterior descending with the left internal mammary artery and the classical technique (sternotomy and extracorporeal circulation) is a safe, minimal risk, effective, long lasting and cost efficient procedure with excellent results at 10 and 15 years.

[Long-term results of reconstructive surgery for mitral insufficiency]

BACKGROUND

Surgical repair is the procedure of choice for mitral insufficiency since it preserves better left ventricular structure and function.

AIM

To assess the long term clinical and echocardiographic results of mitral valve reconstructive surgery.

MATERIAL AND METHODS

A review of clinical and echocardiographic data of 68 patients (34 male, age range 17 to 82 years), subjected to surgical mitral valve repair between December 1991 and March 1998. Preoperative functional capacity of these patients was 2.96 +/- 0.7. Surgical repair was assessed using transesophagic echocardiography in all subjects.

RESULTS

The etiology of mitral insufficiency was degenerative in 43 patients, rheumatic in 10, infectious in 6, ischemic in 5 and miscellaneous in 4. The most frequent pathological findings were dilatation of the mitral ring in 42% of patients, chordae tendinae rupture in 32% and enlargement in 24%. A mitral anuloplasty was done in 90% of patients, a cuadrilateral resection of posterior leaflet in 52% and chordae tendinae transference in 12%. An additional surgical procedure was done in 34% of subjects. Three patients died during hospitalization (4.4%). During the follow up of 36.5 +/- 22.3 months, five patients died and one required a mitral valve replacement. The actuarial survival probability was 95.3 +/- 2.6% at one year and 83.5 +/- 6.5% at five years. The reoperation free survival was 100% at one year and 97.4 +/- 2.5% at five years. At the end of follow up the functional capacity improved to 1.25 +/- 0.4. Echocardiography showed absence of mitral insufficiency in 48.4% of patients, minimal, mild and moderate insufficiency in 35.5, 14.5 and 1.6% of patients respectively.

CONCLUSIONS

Surgical valve reconstruction in mitral insufficiency has satisfactory long term results and should be the procedure of choice for eligible patients.

Inverse association between plasma cholesterol and gallstone disease

BACKGROUND

The association between gallstone disease (gallstones or cholecystectomy) and plasma lipids was evaluated in 2,089 subjects who attended a private health care facility in Mexico City from August 1991 to August 1992.

METHODS

All participants provided data on their sociodemographic status, non-insulin-dependent diabetes mellitus diagnoses, alcohol consumption, and smoking habits; women also gave data regarding their obstetric-gynecologic histories. Ultrasounds of the liver and biliary tract were performed. Cholesterol levels, high-density lipoproteins cholesterol, and triglyceride plasma concentration were determined.

RESULTS

This study shows a strong inverse association between gallstone disease and plasma cholesterol concentration, with OR = 0.61 (95% CI = 0.42-0.89) in the category of 181-239 mg/dL, and OR = 0.49 (95% CI = 0.32-0.77) in the group of 240 mg/dL or more, when compared to 180 mg/dL or less, after adjusting for the following risk factors: gender, age, and body mass index.

CONCLUSIONS

These results suggest an increment in the catabolic pool of cholesterol, reflected in lower levels of plasma cholesterol in subjects with gallstone disease.

[Minimally invasive coronary artery surgery]

BACKGROUND

There is a growing interest to perform a left internal mammary artery (LIMA) graft to the left anterior descending coronary artery (LAD) on a beating heart through a minimally invasive access to the chest cavity.

AIM

To report the experience with minimally invasive coronary artery surgery.

PATIENTS AND METHODS

Analysis of 11 patients aged 48 to 79 years old with single vessel disease that, between 1996 and 1997, had a LIMA graft to the LAD performed through a minimally invasive left anterior mediastinotomy, without cardiopulmonary bypass. A 6 to 10 cm left parasternal incision was done. The LIMA to the LAD anastomosis was done after pharmacological heart rate and blood pressure control and a period of ischemic pre conditioning. Graft patency was confirmed intraoperatively by standard Doppler techniques. Patients were followed for a mean of 11.6 months (7-15 months).

RESULTS

All patients were extubated in the operating room and transferred out of the intensive care unit on the next morning. Seven patients were discharged on the third postoperative day. Duplex scanning confirmed graft patency in all patients before discharge; in two patients, it was confirmed additionally by arteriography. There was no hospital mortality, no perioperative myocardial infarction and no bleeding problems. After follow up, ten patients were free of angina, in functional class I and pleased with the surgical and cosmetic results. One patient developed atypical angina on the seventh postoperative month and a selective arteriography confirmed stenosis of the anastomosis. A successful angioplasty of the original LAD lesion was carried out.

CONCLUSIONS

A minimally invasive left anterior mediastinotomy is a good surgical access to perform a successful LIMA to LAD graft without cardiopulmonary bypass, allowing a shorter hospital stay and earlier postoperative recovery. However, a larger experience and a longer follow up is required to define its role in the treatment of coronary artery disease.

Beneficial effect of carbohydrate maldigestion induced by a disaccharidase inhibitor (AO-128) in the treatment of chronic portal-systemic encephalopathy. A double-blind, randomized, controlled trial

BACKGROUND

The most widely used treatment of portal-systemic encephalopathy (PSE) is the administration of oral, non-absorbable disaccharides. Theoretically, the inhibition of intestinal disaccharidases should induce malabsorption of disaccharides and increase delivery of undigested carbohydrates to the colon, thus stimulating the effects of lactulose and other non-absorbable disaccharides (that is, lactitol and lactose). AO-128 is an N-substituted derivative of valeolamine, an aminocyclitol that selectively inhibits intestinal disaccharidases. This study was performed to investigate whether AO-128 could be used as adjuvant therapy for the treatment of mild PSE in cirrhotic patients.

METHODS

A double-blind, randomized, controlled trial was performed in 35 cirrhotic patients with PSE. Patients were given a 2-week treatment consisting of AO-128 (2 mg three times daily) or an identical placebo. The following features of PSE syndrome were assessed in a semiquantitative fashion before and after I and 2 weeks of therapy: mental state, asterixis, number connection test (NCT), venous blood ammonia concentration, electroencephalogram (EEG), and overall PSE index (PSEI). More patients receiving AO-128 than patients receiving placebo showed >40% improvement in the PSEI (83% versus 35%; P < 0.05). The mean stool pH decreased from 5.8+/-0.3 to 5.5+/-0.3 (P < 0.004) after AO-128 treatment, whereas no changes were observed in the placebo group. The EEG and nitrogen balance did not show significant changes in any of the two groups. A significant improvement was seen in the NCT performance after AO-128 (from grade 2.0+/-1.04 to grade 1.25+/-0.87; P < 0.05). Seven patients treated with AO-128 developed diarrhea, as compared with none in the placebo group (P < 0.05).

CONCLUSION

These results suggest that AO-128 may be useful in the treatment of PSE, although further studies are required to establish the benefit of AO-128 and determine adequate individual doses.

[Coronary surgery. 20 years of follow-up]

BACKGROUND

Since the first surgical coronary revascularization done in Chile in 1971, 5000 such procedures have 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 years old in 1995. No changes in the frequency of diabetes, hypertension, high serum cholesterol or previous myocardial 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%. Follow up information was obtained for 93% of 492 survivors. Actuarial survival at 5, 10, 15 and 20 years was 93 +/- 1, 82 +/- 2, 62 +/- 3 and 41 +/- 4% respectively. Ninety eight +/- 0.7, 89 +/- 2, 73 +/- 4 and 65 +/- 5% of patients remained free of a new myocardial infarction in the same lapses, respectively. Ninety seven +/- 1, 94 +/- 2, 76 +/- 4 and 47 +/- 7% 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.

[Effects of fiber administration in the prevention of gallstones in obese patients on a reducing diet. A clinical trial]

Nearly 30% of the obese patients treated with hypoenergetic diets for weight reduction develop gallstone disease (GD). Until the present time, the use of ursodeoxycholic acid (UDA) is the only available therapeutic measure to avoid the development of GD. Dietary fiber induce a bile acid synthesis. A double-blind clinical trial was conducted to compare the effect of rational diet plus UDA vs a rational diet supplemented with Psyllium plantago (Pp) for the prevention of GD in obese subjects undergoing a weight-reduction diet. Patients with a body mass index (BMI = weight in Kg/square height in m) of 30 Kg/m2 or more and with normal gallbladder and biliary tree ultrasound (GBUS) were included. Weight-reduction diets were individually calculated for each patient according to their energy expenditure (EE). Patients were randomly and blindly assigned either to group I (diet + 750 mg UDA + fiber placebo) or group II (diet + 15 g Pp+ UDA placebo). An anthropometric evaluation was performed to each patient before and after the two-month treatment, as well as resting EE by indirect calorimetry, GBUS and endoscopy for the determination of cholesterol crystals in duodenal bile. Weight reduction was similar in both groups (group I = 6 +/- 2 Kg vs group II = 6 +/- 3 Kg). GD development was observed in one patient of group I (5.5%) and two patients of group II (p > 0.05). All patients with GD lost a minimum of 4 Kg during the study period. GD development did not correlate with the presence of crystals in the duodenal bile at the beginning of the study. Our results suggest a beneficial effect of a rational diet with fiber supplementation to prevent GD development in obese patients included in a weight reduction program.

[Myocardial revascularization with one and two mammary arteries: clinical results and long-term follow-up]

BACKGROUND

Coronary bypass grafts made with internal mammary artery have better long-term results than those made with saphenous vein. It is possible that the use of both mammary arteries would lead to even better results.

AIM

To compare the long-term survival and the incidence of new coronary events of patients, in whom one or two mammary arteries were used as coronary bypass grafts.

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%). Patients that received two mammary arteries had a higher frequency of operative wound complications. Long-term survival was 84% in patients who received one and 83% in patients who received two mammary arteries. The probabilities of being free of myocardial infarction (92 and 82% respectively) and angina (94 and 86% 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.

[Carotid endarterectomy combined with myocardial revascularization: report of 27 patients]

Atherosclerosis is a systemic disease that may involve more than one territory. Myocardial infarction can occur after carotid endarterectomy and stroke is a well documented morbidity of coronary artery bypass grafting. To optimize results, we have performed concomitant carotid endarterectomy and myocardial revascularization in selected cases, with severe disease in both territories. During a 13-year period, 27 patients were submitted for this procedure, 21 (77.8%) were male and the average age was 67.6 years (range 59-81). All patients had high-grade internal carotid artery stenosis, five (18.5%) were symptomatic. Coronary artery disease symptoms were: unstable angina in 12 patients (44.4%) and effort angina in 15 (55.6%). Two patients (7.4%) required reintervention for postoperative bleeding. Two cases (7.4%) had transient renal dysfunction. One patient, with multiple organ failure, died on the 16th postoperative day (3.7%). Follow up was obtained in 26 patients (96.3%). Survival at 5 years was 80.6%, 95.7% of those patients were free of any neurologic symptom. Combined carotid and coronary surgery is a safe treatment option for atherosclerosis of multiple territories in selected patients; long term benefits are also obtained.

[Primary biliary cirrhosis: clinical features and survival of a Mexican population]

BACKGROUND

PBC progresses to cirrhosis and results in death due to liver failure or bleeding portal hypertension. Data of the clinical characteristics and survival of PBC patients allows the assessment of therapeutical alternatives as well as the establishment of inclusion criteria for liver transplantation.

AIMS

One hundred and twenty patients with histological diagnosis of PBC, admitted from 1972 to 1992, were selected with the purpose of studying the clinical and biochemical characteristics and survival.

METHODS

Patients who underwent liver transplant or those who had an incomplete follow-up were excluded.

RESULTS

Therefore only 80 patients were included: these were seventy five women and five men, with mean age 46 +/- 11 years (X +/- SD) to whom demographic data, biochemical analysis, liver function (Child-Pugh) and liver damage (Ludwig) were recorded at the time of histological diagnosis, which was considered zero for calculating the survival (Kaplan Meier). The most common symptoms at diagnosis were pruritus in 63 patients, jaundice in 48, asthenia and adynamia in 55 patients. Eight cases were asymptomatic. According to Child-Pugh's classification, patients were grouped as follows: forty in stage A, 29 in B, and three in C; and according to liver damage (Ludwig), 8 in grade I, 28 in grade II, 22 in grade III and 14 in grade IV. The most frequent clinical associations were Sjögren's syndrome, in 30% of patients, although one case was associated to progressive muscular dystrophy and another one to multiple myeloma and hypothyroidism; in 58.7% of the cases, antimitochondrial antibodies were negative. One year survival was 75%, five years 44%, and seven years 13%.

CONCLUSIONS

The most important characteristics of the studied patients were elevated percentage of negative antimitochondrial antibodies and short survival. it is important to impel the development of liver transplantation as the only mean to improve survival.

[Pulmonary thromboendarterectomy: a case of surgical treatment of chronic pulmonary thromboembolism under circulatory arrest with deep hypothermia]

Pulmonary thromboendarterectomy under circulatory arrest and deep hypothermia is presently a curative treatment for pulmonary hypertension secondary to chronic pulmonary artery thromboembolic occlusion, but is still not frequently performed around the world. We report here the first successful pulmonary thromboendarterectomy under circulatory arrest performed in Chile. The patient was a 37 year old white man, high school teacher, with a 5 months history of effort dyspnea and cough. Pulmonary hypertension secondary to chronic pulmonary thromboembolism was confirmed by angiography and echocardiography. The patient was operated on April 27, 1995. After the operation the patient had an immediate and maintained normalization of his pulmonary hemodynamics. He presented periods of delirium that postponed mechanical ventilation disconnection until the 7th postoperative day, after which he had an uneventful neurological recovery. Before hospital discharge a control angiography showed complete patency of the pulmonary artery system with no evidence of residual thrombi. Presently he is enjoying a normal life and back to his teaching activities.

[Surgical myocardial revascularization during the 1st 15 days of evolution of acute myocardial infarction]

Revascularization significantly improves early and late prognosis in acute myocardial infarction and has prompted substantial changes in therapeutic stategies. 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 in 8 (6%), double vessel disease in 32 (23%), triple vessel disease in 85 (61%) and left main vessel disease in 13 (9%). Indications for surgery were postinfarction angina in 92 patients (66%), multiple severe coronary stenoses in 18 (13%), infarction of less than six hours from onset in 16 (11%), acute angioplasty failure in 7 (5%) and cardiogenic shock in 7 (5%). 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% (6/140). Among patients with failed angioplasty and cardiogenic shock, mortality was 23% (7/140), among patients with postinfarction angina this figure was 2.1% (2/92). No patient operated within 6 hours of infarction onset or due to severe coronary stenosis, died. Ninety seven percent of patients were followed during mean of 49 months. Three patients had a new acute myocardial infarction, two had sudden death and two died of unrelated causes. One required angioplasty and none was reoperated. Five years actuarial survival was 95% and the actuarial probability of being free of acute myocardial infarction, angioplasty or reoperation at five years was 99 and 100% respectively. It is concluded that early surgical revascularization in cute myocardial infarction is safe and has excellent long term results.

[Retrograde cerebral perfusion during circulatory arrest with deep hypothermia. A new technique for brain protection in surgery of ascending aorta and aortic arch]

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%) 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 dialysis. There was no case of Q wave infarction nor congestive heart failure in the perioperative period. Follow-up was 100% 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.

[Papillary muscle rupture in myocardial infarction]

We report nine patients with acute mitral regurgitation secondary to post-infarction papillary rupture operated between 1980 and 1992. Seven cases had posterior papillary muscle rupture. All patients were in critical conditions with pulmonary edema at the moment of surgery. In eight cases, mitral valve replacement was performed (4 with mechanical prostheses) and in one, the valve was repaired with papillary muscle reimplantation. Six cases were also subjected to myocardial revascularization with sapheneous vein grafts. Two patients (22%) died during the postoperative period and 4 had postoperative complications. The seven survivors have been followed during 6 to 115 month. Of theses, one died six month after surgery due to congestive heart failure, three are in functional class I and the rest in functional class II. It is concluded that, although mitral valve replacement for papillary muscle rupture has a high operative mortality and morbidity, long term results are satisfactory.

[Reactivity of internal mammary artery and saphenous vein used in human myocardial revascularization: studies with endogenous vasoconstrictors and vasodilators]

Biopsies of human internal mammary artery and saphenous vein were examined to ascertain the functional integrity of these vessels employed in myocardial revascularization. Studies were performed in vascular rings derived from 28 patients without previous consideration of age, sex, underlying additional pathology or drug treatments previous to and during surgery. Isometric muscle contraction of the circular muscle layer was monitored. Endothelin-1 (ET) is equipotent as a vasoconstrictor in arteries and veins, with a potency at least 10 to 100-fold that of noradrenaline (NA) or serotonin (5-HT). The potency of ET, NA or 5-HT is unaltered by mechanical removal of the endothelial cell layer. Arterial rings precontracted with NA relaxed in a concentration-dependent fashion in the presence of acetylcholine and sodium nitroprusside. Whereas the potency of nitroprusside was unaltered by removal of the endothelium, the efficacy of acetylcholine was greatly reduced. Saphenous vein rings were refractory to acetylcholine but not nitroprusside. Results open new perspectives to explain the larger patency of internal mammary artery grafts as compared to that of saphenous vein grafts in human myocardial revascularization.

[Surgery of acute mitral valve insufficiency]

Between January 1980 and December 1990, 16 patients with acute mitral insufficiency were operated on an emergency basis at our institution. They represented 1.8% of all mitral surgical cases. All of them were in acute pulmonary edema and 7 in cardiogenic shock. The etiology was ischemic in 6, degenerative in 4, infectious in 3, degenerative and infectious in 2 and traumatic in 1. The pathologic mechanism was chordal rupture in 8 patients (5 anterior) and papillary muscle rupture in the other 8 (5 posterior). A mitral valve replacement was performed in all cases. Two patients died and 7 had morbidity in the postoperative period. One patient died 6 months after surgery of congestive heart failure. Ten patients are in NYHA functional class I at a mean follow-up of 48.1 months. Acute mitral insufficiency has different etiologies and pathologic mechanisms. In spite of the severe clinical condition of these patients, mitral valve replacement has good immediate and long-term results.

[Dissection of the ascending aorta (type A): diagnostic aspects, surgical treatment and long-term follow-up]

Aortic replacement is the treatment of choice and improves the natural history of dissections involving the ascending aorta. Forty patients (23 male), aged 49.4 years, have been operated at the hospital Clínico de la Universidad Católica. Twenty six presented with acute dissections. Angiography conformed the dissection in 63.3% and computed axial tomography in 84.6% of patients; lately, transesophageal echocardiography has become the most sensitive diagnostic method. Twenty three patients (57.5%) were subjected to emergency operations and 17 to semielective procedures. In 24 patients (60%) ascending aorta was replaced and in 16 a composite graft was used. Operative mortality was 27.5%. Univariate analysis showed that the period in which the operation was performed and the presence of limb ischemia were the only independent predictors of operative mortality. Long term follow up was achieved in 26 patients (89.6%). Actuarial 5 year survival without considering operative mortality was 87.9%. It is concluded that patients with acute dissections involving the ascending aorta should be operated as soon as the imaging diagnosis is complete and, since this is a palliative procedure, a close follow up is required for early detection of complications.

[Interventricular rupture following myocardial infarction. Surgical treatment and long-term follow-up]

The natural course of post myocardial infarction ventricular septal defect is towards cardiogenic shock and death. 50% in the first week, over 90% a year latter. Between 1973-1989, 28 patients where operated on. Before surgery 14 patients (53%) where in Killip IV, 5 patients (19%) in III, 5 patients (19%) in II and 2 patients in I. The repair was accomplished under hypothermia and cardioplegia, with the insertion of a Teflon patch to close the defect in 20 patients (70%). Complementary procedures (CABG, Pacemaker, repair of dissections) were performed in 12 patients (47%). Three patients (10%) could not be weaned from the pump; another 10 (36%) died before discharge: 2 with multisystem failure and sepsis, the other 8 with cardiogenic shock (4 with residual VSD). The only independent predictor of operative mortality, by univariate analysis, was preoperatory cardiogenic shock. All 15 survivors (100%) where followed between 5 months and 14.5 years (mean 104.5 months). Two patients died at 4 years, one at 10, another at 10.5 years. The actuarial probability of being alive after discharge was 100% at 4 years, 75% at 5, and 50% at 10 years. At last follow up only 2 patients had mild dyspnea, the remaining where asymptomatic. Surgical treatment provides an opportunity to improve this otherwise dismal survival and offers a surprising good long term result. An early diagnosis and efficient repair, before the onset of cardiogenic shock, should provide better results.

[Fever of unknown origin. A study of cases seen at the third level]

Clinical records of 160 patients admitted with fever of unclear origin were reviewed. Of them, all cases with fever of obscure origin (FOO) were selected based on the following criteria: at least two weeks with fever, with an oral temperature of 37.5 degrees C or more during hospitalization and whose clinical history, physical examination, hemocytologic data, erithrosedimentation rate, urinalysis, febrile tests, glutamic-piruvic transaminase, chest and abdomen radiographies were not suggestive of any specific diagnosis. 32 cases of FOO were found, but only the 30 which had been studied previously in another hospital were considered for analysis. Of these 30 patients, 18 were men and 12 women, with a mean age of 36.3 (range 19-64). Infectious diseases caused 40 percent and neoplastic disease 27 percent of cases. The single most frequent cause was non-Hodgkin lymphoma in four cases, followed by tuberculosis and Hodgkin's disease in three patients each. In four cases the cause of fever was not identified. Eleven patients required exploratory laparotomy; in nine of them it was usefull for diagnosis. Our results show a high proportion of neoplastic diseases, probably related with patient's selection and with intrinsic diagnostic difficulty of these kind of diseases.

Characterization of acetylcholinesterase from human heart auricles: evidence for the presence of a G-form sensitive to phosphatidylinositol-specific phospholipase c

1. Acetylcholinesterase (AChE) is an important enzyme of the cholinergic system in mammals. 2. We report here the subcellular association of the AChE molecular forms in the normal human heart auricle. 3. Both globular (G) and asymmetric (A) forms were identified using velocity sedimentation and sequential extraction procedures. 4. G forms corresponds to 84% and A forms account for 16% of the total AChE activity. 5. Of G forms 64% of AChE activity correspond to the G1 monomer and of the A forms the class I-A account for 80% of AChE activity. 6. In addition, treatment of the cardiac membranes with the enzyme phosphatidylinositol-specific phospholipase c (PIPLC) results in the solubilization of AChE activity. 7. This means that a G2 AChE dimer with a glycolipid anchoring domain is present in the human heart.

[The long-term evolution of aortic valve replacement with a mechanical prosthesis: experience with the Starr-Edwards (1965-1974) and Bjork-Shiley (1973-1981) prostheses]

We compared the short- and long-term results of isolated aortic valve replacement in 98 patients receiving a Starr-Edwards (SE) prosthesis from 1965 to 1974 and 80 pts receiving a Bjork-Shiley (BS) prosthesis from 1973 to 1981 at our institution. Operative mortality was 20% (SE) and 6% (BS). Follow-up information was obtained in 88% (SE) and 96% (BS) of pts discharged alive. The mean period of follow up was 8.2 and 6.7 years respectively. The 5 and 10 year actuarial survival rates were 72% and 61% (SE) vs 89% and 83% (BS). Complications per 100 pt-years among pts with SE and those with BS were: systemic emboli 2.8 vs 0.6, major hemorrhagic events 1.25 vs 1.36, perivalvular leak 1.6 vs 1.15, endocarditis 0.31 vs. 0.39, prosthetic thrombosis 0 vs 0.58 and ball variance 0.47 vs 0, respectively. Some of these differences may reflect shortcomings of the initial surgical experience during the period in which the SE prosthesis was used, rather than different performance of both valves.

[Wolff-Parkinson-White syndrome: late results of surgical treatment]

We followed 25 patients operated on for Wolff-Parkinson-White syndrome between August 1985 and October 1989. Their mean age was 37 +/- 12 years and arrhythmia had been present for 5 to 30 years. A mean of 3.3 +/- 1.2 antiarrhythmic agents had failed in controlling recurrences. Tachycardia was orthodromic in 21 patients and antidromic in 1, while 3 patients presented rapid atrial fibrillation with hemodynamic deterioration. Drug refractoriness (n = 23) or intolerance (n = 2) were the main surgical indications. The location of accessory pathways was lateral in 19 patients, anteroseptal in 3, posteroseptal in 2, postero lateral in 1 and right lateral in 1 patient. One patient had a double pathway. There was no surgical mortality. After a follow-up period ranging from 1 to 50 months recurrence of arrhythmia was observed in one patient and electrophysiologic evaluation showed persistence of a left lateral pathway in another. The remaining 24 patients are free of symptoms at the end of follow up. Thus, surgical treatment is a curative therapy for most patients with WPW.

[The heart transplant: the current status]

Interest in cardiac transplantation started with the investigations of Carrel in 1905. Clinical experience started in 1967 but early results were discouraging mainly due to difficulties with diagnosis and treatment of rejection. The introduction of cardiac biopsy to diagnose and cyclosporine to treat rejection vastly improved the success of the procedure. Large number of patients have been operated in different centers and criteria for selecting or excluding patients have emerged. Selection of the donor and improvements in surgical technique have also contributed to better results. Currently, 80% survival in the first year and 70% at 5 years are to be expected, and cardiac transplantation is a definite therapeutic option for selected patients with end-stage cardiac disease. However, significant problems remain to be solved, such as cyclosporin nephrotoxicity, secondary hypertension and occlusive vascular disease of the transplanted heart.

[Atrial ectopic tachycardia. A variety of incessant tachycardia]

A 19 year old patient with incessant supraventricular tachycardia was submitted to electrophysiologic study. An ectopic left atrial focus was demonstrated. Intraoperative mapping localized the focus to the upper left atrial quadrant. Successful surgical isolation of the focus was possible. The patient is currently asymptomatic and arrhythmia free.

[Surgery of evolving myocardial infarction]

Limitation of infarct size has been proven to improve the prognosis in patients with recent myocardial infarction (MI). Emergency coronary bypass surgery may be used for this aim. We operated on 44 such patients within 15 days of onset of MI. Operation was done within 6 hr in 11 patients and later on in the other 33, due to post infarction angina or incomplete MI. One patient died in the perioperative period. Thirty nine patients were followed at a mean of 33 months: 2 have angina, one dyspnea and the rest is asymptomatic. We believe that bypass surgery is an effective treatment in selected patients with recent MI.

Disc dislodgment in Björk Shiley mitral valve prosthesis: two successfully operated cases

Two patients with Björk Shiley mitral valve replacement had migration and embolization of the occluding disc. One patient suffered migration of the disc a few hours after surgery and the other had a strut fracture with disc translocation six years after the initial operation. Clinical signs in both cases were pulmonary edema, cardiogenic shock, and absence of prosthetic sounds. Both patients were reoperated on an emergency basis, recovering after a complicated postoperative course. They are on functional Class I, 8 and 1 years later, respectively, with their dislodged discs still in the abdominal aorta. The only hope for survival in these patients is emergency reoperation, once the prosthetic mitral valve dysfunction is confirmed.

Surgical removal of entrapped endocardial leads without using extracorporeal circulation

Of 267 patients having a tined endocardial lead implanted from 1978 to December 1983, three (1.1%) developed pulse generator pocket infection. Proper treatment of this complication involves removal of the pulse generator, continued external pacing via the implanted lead, pocket drainage and administration of specific antibiotics until the infected area clears. In two patients, the electrode could not be removed by traction. A sternotomy was performed, the pericardium was opened, the endocardial electrode was located by palpation, and a purse string suture (PSS) was prepared around it on the right ventricular wall. A new myocardial electrode with its corresponding generator was then implanted to reestablish pacing. Through the PSS the myocardium was incised, the distal end of the endocardial lead was exteriorized and severed, and the PSS was tied. The remaining lead was withdrawn proximally and the surgical wounds were closed. The results of this procedure have been been excellent, allowing the removal of the entrapped leads, with continuous pacing and without the need for extracorporeal circulation.