[Surgical results of video-assisted thoracoscopic thymectomy for treatment of Juvenile Myasthenia Gravis]

INTRODUCTION

Juvenile myasthenia gravis (JMG) is an autoimmune disease affecting the neuromuscular junction that appears before 19 years of age with varying degrees of weakness of different muscle groups. The main treatment is pharmacological, but thymectomy has also demonstrated to improve remission rates.

OBJECTIVE

To describe the clinical characteristics and postoperative course of pediatric patients with JMG who underwent video-assisted thoracoscopic (VATS) thymectomy. Clinical Serie: Six pa tients who underwent VATS thymectomy between March 2011 and June 2019. The age range at diag nosis was between 2 and 14 years and the average age at surgery was 7 years. All patients were under treatment with pyridostigmine bromide associated with immunosuppression with corticosteroids before surgery. The interval between diagnosis and thymectomy was 21.5 months on average. VATS was performed by left approach, and there was no perioperative morbidity or mortality. The average hospital stay was 2 days. Three patients remain with no symptoms and without corticotherapy. Two patients were on corticosteroids, but in smaller doses than previous to surgery. One patient presented a crisis requiring hospitalization and ventilatory support during follow-up.

CONCLUSION

VATS thy mectomy is part of the treatment for JMG. In this series, it appears as a safe approach and its results were favorable.

Morbidity and Mortality in Patients with Perioperative COVID-19 Infection: Prospective Cohort in General, Gastroesophagic, Hepatobiliary, and Colorectal Surgery

Background

Severe acute respiratory syndrome due to coronavirus 2 has rapidly spread worldwide in an unprecedented pandemic. Patients with an ongoing COVID-19 infection requiring surgery have higher risk of mortality and complications. This study describes the mortality and morbidity in patients with perioperative COVID-19 infection undergoing elective and emergency surgeries.

Methods

Prospective cohort of consecutive patients who required a general, gastroesophageal, hepatobiliary, colorectal, or emergency surgery during COVID-19 pandemic at an academic teaching hospital. The primary outcome was 30-day mortality and major complications. Secondary outcomes were specific respiratory mortality and complications.

Results

A total of 701 patients underwent surgery, 39 (5.6%) with a perioperative COVID-19 infection. 30-day mortality was 12.8% and 1.4% in patients with and without COVID-19 infection, respectively (p < 0.001). Major surgical complications occurred in 25.6% and 6.8% in patients with and without COVID-19 infection, respectively (p < 0.001). Respiratory complications occurred in 30.8% and 1.4% in patients with and without COVID-19 infection, respectively (p < 0.001). Mortality due to a respiratory complication was 100% and 11.1% in patients with and without COVID-19 infection, respectively (p < 0.006).

Conclusions

30-day mortality and surgical complications are higher in patients with perioperative COVID-19 infection. Indications for elective surgery need to be reserved for non-deferrable procedures in order to avoid unnecessary risks of non-urgent procedures.

Bariatric Surgery in Cirrhotic Patients: a Matched Case-Control Study

INTRODUCTION

Laparoscopic bariatric surgery (LBS) in liver end-stage organ disease has been proven to improve organ function and patients' symptoms. A series of LBS in patients with cirrhosis have shown good results in weight loss, but increased risk of complications. Current literature is based on clinical series. This paper aims to compare LBS (69% gastric bypass) between patients with cirrhosis and without cirrhosis.

METHODS

We conducted a retrospective 1:3 matched case-control study including bariatric patients with cirrhosis and without cirrhosis. Demographics, operative variables, postoperative complications, long-term weight loss, and comorbidity resolution were compared between groups.

RESULTS

Sixteen Child A patients were included in the patients with cirrhosis (PC) group and 48 in patients without cirrhosis (control) group. Mean age was 50 years; preoperative BMI was 39 ± 6.8 kg/m². Laparoscopic gastric bypass and laparoscopic sleeve gastrectomy were performed in 69% and 31%, respectively. Follow-up was 81% at 2 years for both groups. PC group had a higher rate of overall (31% vs. 6%; p < 0.05) and severe (Clavien-Dindo ≥ III; 13% vs. 0%; p = 0.013) complications than that of the control group. Mean %EWL of PC at 2 years of follow-up was 84.9%, without differences compared with that of the control group (83.1%). Comorbidity remission in PC was 14%, 50%, and 85% for hypertension, type 2 diabetes, and dyslipidemia, respectively. Patients without cirrhosis had a higher resolution rate of hypertension (65% vs. 14%, p = 0.03).

CONCLUSION

LBS is effective for weight loss and comorbidity resolution in patients with obesity and Child A liver cirrhosis. However, these results are accompanied by significantly increased risk of complications.

Neuropeptide Y is released from human mammary and radial vascular biopsies and is a functional modulator of sympathetic cotransmission

The role of neuropeptide Y (NPY) as a modulator of the vasomotor responses mediated by sympathetic cotransmitters was examined by electrically evoking its release from the perivascular nerve terminals of second- to third-order human blood vessel biopsies and by studying the peptide-induced potentiation of the vasomotor responses evoked by exogenous adenosine 5' triphosphate (ATP) and noradrenaline (NA). Electrical depolarization of nerve terminals in mammary vessels and radial artery biopsies elicited a rise in superfusate immunoreactive NPY (ir-NPY), which was chromatographically identical to a standard of human NPY (hNPY); a second peak was identified as oxidized hNPY. The amount released corresponds to 4-6% of the total NPY content in these vessels. Tissue extracts also revealed two peaks; hNPY accounted for 68-85% of the ir-NPY, while oxidized hNPY corresponded to 7-15%. The release process depended on extracellular calcium and on the frequency and duration of the electrical stimuli; guanethidine blocked the release, confirming the peptide's sympathetic origin. Assessment of the functional activity of the oxidized product demonstrated that while it did not change basal tension, the NA-evoked contractions were potentiated to the same extent as with native hNPY. Moreover, NPY potentiated both the vasomotor action of ATP or NA alone and the vasoconstriction elicited by the simultaneous application of both cotransmitters. RT-PCR detected the mRNA coding for the NPY Y(1) receptor. In summary, the release of hNPY or its oxidized species, elicited by nerve terminal depolarization, coupled to the potentiation of the sympathetic cotransmitter vasomotor responses, highlights the modulator role of NPY in both arteries and veins, strongly suggesting its involvement in human vascular sympathetic reflexes.

Release and functional role of neuropeptide Y as a sympathetic modulator in human saphenous vein biopsies

Transmural electrical stimulation of the sympathetic nerve endings of human saphenous vein biopsies released two forms of NPY identified chromatographically as native and oxidized peptide. The release process is dependent on extracellular calcium, the frequency, and the duration of the stimuli. While guanethidine reduced the overflow of ir-NPY, phenoxybenzamine did not augment NPY release, but increased that of noradrenaline. Oxidized NPY, like native NPY, potentiated the noradrenaline and adenosine 5'-triphospahate-induced vasoconstriction, an effect blocked by BIBP 3226 and consonant with the RT-PCR detection of the mRNA encoding the NPY Y1 receptor. These results highlight the functional role of NPY in human vascular sympathetic reflexes.

[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.

[Infection of ascending aortic graft: treatment with surgical cleaning, graft preservation and transposition of muscle flaps. Report of two cases]

Mediastinitis with graft infection is a serious complication of ascending aorta replacement. We report two cases of graft infection, treated with surgical cleaning, graft preservation and transposition of muscle flaps. A 62 years old male was admitted 34 days after an ascending aortic grafting due to a sternal dehiscence and mediastinitis. Antimicrobial treatment was started and a surgical cleaning performed, leaving an open sternotomy. Three days later, the thoracic cavity was closed with a rectus abdominis muscle flap. After 23 months of follow up, the patient is well and without evidence of infection. A 74 years old male was subjected to an aortic valve and ascending aorta replacement and a myocardial revascularization. In the postoperative period, the patient developed septic signs, and a purulent drainage. A CAT scan showed a liquid collection surrounding the aortic graft. On tW Sixteenth postoperative day, a surgical cleaning was performed and the thorax was closed with the pectoralis major muscle. After 10 months of follow up, the patient is in Good condition and without evidence of infection.

[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.

[Infective endocarditis: short and long-term results in 261 cases managed by a multidisciplinary approach]

BACKGROUND

Early diagnosis, an effective treatment and prompt recognition of complications are essential to improve the prognosis of infective endocarditis (IE).

AIM

To report the results of a multidisciplinary approach to diagnosis and management of patients with IE at the Universidad Católica de Chile Hospital.

PATIENTS AND METHODS

The clinical history, diagnosis, treatment and outcome of 261 episodes (Duke criteria) of IE admitted between January 1980 and January 1999 were analyzed. These included 185 episodes of native, 73 of prosthetic valve and 3 of nonvalvular IE.

RESULTS

Sixty nine percent of patients were men and the mean age was 49 +/- 16 years. Seventy five percent had a definite diagnosis of IE (Duke). S. viridans, staphylococci and enterococci together constituted 85% of the isolated bacterial strains. Twenty seven had culture-negative IE, related to a high incidence of antibiotic therapy prior to diagnosis. Transesophageal echocardiography was performed in 102 cases and it detected vegetations in 91% of aortic and 96% of mitral IE, rupture or prosthesis dehiscence in 67% of aortic and 52% of mitral IE and abscesses in 51% of aortic and 15% of mitral IE. Fifty one percent developed heart failure and 34% had embolic events. S. aureus IE was associated to a higher incidence of embolic events, complications which contraindicated surgery and increased mortality rate (27%). Of all patients, 40% were treated exclusively with antibiotics, 52% were operated on and 8% had surgical indication but were nonoperable because of serious complications. The overall mortality was 16.3%: 13% in the medical, 9% in the surgical and 81% in the non-operable groups. The type of treatment and mortality rates did not differ between IE of native valves and prosthetic valves. Long term follow up showed survival rates of 73% at 5 years and 66% at 10 years.

CONCLUSION

A multidisciplinary approach may be very helpful to improve the prognosis of IE.

[Traumatic rupture of thoracic aorta and non operative treatment of concomitant splenic lesion. Case report]

We report a 26 years old male that suffered a motorcycle accident resulting in a traumatic aortic rupture and splenic laceration. He was subjected to a surgical repair of the aortic lesion under complete heparinization. The splenic rupture was non operatively managed successfully.

[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.

[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.

[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.

[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.

[Metalloproteinase activity in arteries and veins. Regulation with doxycycline]

BACKGROUND

Alterations in the synthesis and degradation of extracellular matrix occur during atherogenesis. Metalloproteinases, whose activity may be inhibited with doxycicline in other tissues, play an important role in this process.

AIMS

1. To characterize metalloproteinase activities in internal mammary artery and saphenous vein, and 2. To assess the effect of doxycicline in the activity of metalloproteinases of these vessels and of cultured smooth muscle cells.

METHODS

Segments of internal mammary arteries and saphenous veins and cultured smooth muscle cells were incubated with and without doxycicline. Metalloproteinases activity was assessed by zymography and Western Blot.

RESULTS

Activity of metalloproteinase-9 in saphenous veins was 217% less than in internal mammary arteries. In these vessels doxycicline decreased metalloproteinase-9 activity by 207% and metalloproteinase-2 by 290%. Western Blot analysis showed that docycicline also inhibited metalloproteinase-1 expression. In cultured smooth muscle cells, the median inhibitory concentration of doxycicline for metalloproteinase-2 was 138 microM (r2 = 0.82).

CONCLUSIONS

Internal mammary arteries and saphenous veins have different metalloproteinase activities, that are inhibited by doxycicline.

[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.

[Hypertrophic cardiomyopathy with two episodes of recuperated sudden death. Report of the first implantable defibrillator cardioverter inserted in Chile]

We report a 29 years old male with a non obstructive hypertrophic cardiomyopathy that survived two episodes of cardiac arrest and with a familiar history of the disease and sudden death. He had an implant of an automatic implantable cardioverter defibrillator by a left anterior thoracotomy with intraoperative electrophysiology. The postoperative outcome was uneventful. After one year of follow up, the patient is in good functional capacity and the implanted device has not performed defibrillations.

[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.

[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.

[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.

Ultrastructural myocardial preservation during coronary artery surgery: a controlled, prospective, randomized study in humans

Potassium cardioplegia was compared with normothermic, intermittent ischemic arrest in 30 patients undergoing multiple coronary artery bypass grafts. Group 1 comprised 15 patients in whom cold potassium cardioplegia with St. Thomas' Hospital solution was used. In Group 2 were 15 patients who underwent intermittent ischemic arrest during the construction of the distal anastomoses. Two myocardial transmural left ventricular biopsies were done in each patient. There was no operative mortality. Electron microscopical examination showed normal myocardial ultrastructure in both groups. In particular, mitochondria were well preserved in all samples. The postoperative electrocardiogram demonstrated a new Q wave in 1 patient in Group 2 whose level of the myocardial isoenzyme of creatine phosphokinase (CPK-MB) was within the normal range. The peak CPK-MB release in Group 1 was 23.2 +/- 20.1 IU and in Group 2, 19.9 +/- 15.1 IU. This difference was not statistically significant. The mean period of anoxic arrest in Group 1 was 49.5 +/- 15 minutes and in Group 2, 25.5 +/- 8 minutes (p less than 0.001). Total cardiopulmonary bypass time in Group 1 was 114.5 +/- 20 minutes and in Group 2, 90.2 +/- 16 minutes (p less than 0.01). It is concluded that both techniques can preserve myocardial subcellular architecture during multiple coronary artery bypass grafting in patients with normal left ventricular function.

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.