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M J Irarrázaval

Publications and source records attributed to M J Irarrázaval.

At least 19 recordsLinked to original sources
PubMed2004

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.

Adenosine Triphosphate↗
PubMed2004

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.

Adenosine Triphosphate↗
PubMed2001

[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.

Aged↗
PubMed2001

[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.

Adult↗
PubMed2000

[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.

Adult↗
PubMed2000

[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.

Adolescent↗
PubMed2000

[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.

Adenosine Triphosphate↗
PubMed1999

[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.

Adult↗
PubMed1998

[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.

Aged↗
PubMed1997

[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.

Animals↗
PubMed1997

[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.

Disease-Free Survival↗
PubMed1996

[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.

Adult↗
PubMed1996

[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.

Adult↗
PubMed1995

[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.

Aged↗
PubMed1995

[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.

Aged↗
PubMed1994

[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.

Adult↗
PubMed1994

[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.

Endothelium, Vascular↗