Search PubMed⌕ Search

Biomedical subjects

G Lema

Publications and source records attributed to G Lema.

At least 37 records · Page 2Linked to original sources
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

Effects of extracorporeal circulation on renal function in coronary surgical patients.

We prospectively studied perioperative changes of renal function in 12 previously normal patients (plasma creatinine < 1.5 mg/dL) scheduled for elective coronary surgery. Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were measured with inulin and 125I-hippuran clearances before induction of anesthesia, before cardiopulmonary bypass (CPB), during hypo- and normothermic CPB, after sternal closure, and 1 h postoperatively. Renal and systemic vascular resistances were calculated. Urinary N-acetyl-beta-D-glucosaminidase (NAG) and plasma and urine electrolytes were measured, and free water, osmolal, and creatinine clearances, and fractional excretion of sodium and potassium were calculated before and after surgery. 125I-hippuran clearance was lower than normal in all patients before surgery. During hypothermic CPB, ERPF increased significantly (from 261 +/- 107 to 413 +/- 261 mL/min) and returned toward baseline values during normothermia. GFR was normal before and after surgery and decreased nonsignificantly during CPB. Filtration fraction was above normal before surgery and decreased significantly during CPB (0.38 +/- 0.09 to 0.18 +/- 0.06). Renal vascular resistance (RVR) was high before surgery and further increased after sternotomy (from 18,086 +/- 6849 to 30,070 +/- 24,427 dynes.s.cm-5), decreasing during CPB to 13,9647 +/- 14,662 dynes.s.cm-5. Urine NAG, creatinine, and free water clearances were normal in all patients both pre- and postoperatively. Osmolal clearance and fractional excretion of sodium increased postoperatively from 1.54 +/- 0.06 to 12.47 4/- 11.37 mL/min, and from 0.44 +/- 0.3 to 6.07 +/- 6.27, respectively. We conclude that renal function does not seem to be adversely affected by CPB.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Low urinary dopamine excretion associated to low sodium excretion in normotensive Piaroa Amazonian ethnia compared to urban subjects.

The objective of this work was to compare urinary dopamine, noradrenaline, adrenaline, sodium and potassium excretion in a group of normotensive Piaroa Amazonic ethnia who do not use salt in their regular food intake, against a group of urban normotensive citizens known to have a high salt intake in their regular meals. Twenty adult normotensive Piaroa subjects living in the Amazonas forest, 11 men and 9 women, 23-72 years old, and 33 normotensive urban citizens, 25-70 years old, 17 men and 17 women, were included in the study. After a 10 min. rest, an average of three supine systolic (SBP) and diastolic (DBP) blood pressure recordings was obtained. Piaroas subjects SBP and DBP were 111.3 +/- 2.9 mmHg and 62.7 +/- 1.9 mmHg respectively; urban subjects SBP and DBP were 111.8 +/- 2.2 mmHg and 70.3 +/- 1.6 mmHg respectively. Supine heart rate was lower in Piaroas (58.0 +/- 1.8 beats/min) than in urban subjects (76.5 +/- 1.9 beats/min), p < 0.05. Sodium urinary excretion was much lower in Piaroas (12.6 +/- 5.2 mmol/24 h) when compared to urban subjects (210.7 +/- 24.5 mmol/24 h), p < 0.01. No difference was found in daily urinary potassium excretion between Piaroas and urban subjects (50.4 +/- 7.2 mmol/24 h vs 45.1 +/- 7.4 mmol/24 h). Urinary dopamine excretion was lower in Piaroas (314.7 +/- 40.1 micrograms/24 h) in comparison to urban subjects (800.4 +/- 59.2 micrograms/24 h), p < 0.05. Daily urinary noradrenaline and adrenaline excretion were 67.9% and 85.4% respectively lower in Piaroas than in urban subjects. In conclusion, lower amounts of sodium daily intake are associated to lower kidney dopamine production in Piaroas as compared to urban subjects. Apparently indigenous tribes might require less kidney dopamine synthesis to excrete the very small amounts of salt they consume in their regular food intake. The opposite was found in urban subjects; more kidney dopamine synthesis would be required for larger amounts of urinary sodium excretion. In this population, essential hypertension has been associated to a failure of the natriuretic mechanism triggered by dopamine onkidney tubules.

Adult↗
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

Thermoregulatory vasoconstriction increases the difference between femoral and radial arterial pressures.

OBJECTIVE: Thermoregulatory vasoconstriction locally increases arterial wall tension and arteriolar resistance, thereby altering physical properties of the arteries. The arterial pressure waveform is an oscillatory phenomenon related to those physical characteristics; accordingly, we studied the effects of thermoregulatory vasomotion on central and distal arterial pressures, using three hydraulic coupling systems having different dynamic responses. METHODS: We studied 7 healthy volunteers. Central arterial pressure was measured from the femoral artery and distal pressure was measured from the radial artery, using 10.8-cm long, 20-gauge catheters. Three hydraulic coupling systems were used: (1) a 10-cm-long, 2-mm internal diameter connector; (2) a 150-cm-long, 1-mm internal diameter connector (Combidyn 520-5689, B. Braun, Melsungen, Germany); (3) a 180-cm long, 2-mm internal diameter connector (Medex MX564 and MX562, Medex Inc., Hillard, OH). Brachial artery pressure was measured oscillometrically. Core temperature was measured at the tympanic membrane. The vasomotor index, defined as finger temperature minus room temperature, divided by core temperature minus room temperature, was used to estimate the degree of vasoconstriction. Constriction was considered near maximal when the index was less than 0.1, and minimal when it exceeded 0.75. Measurements were taken every 3 min. Baseline readings were obtained when subjects were warm. They then were cooled by exposure to 20 degrees C to 22 degrees C room air and a circulating-water mattress set at 4 degrees C until index was less than 0.1. They then were rewarmed by increasing water temperature to 42 degrees C and adding a forced-air warmer until the vasomotor index exceeded 0.75. Data were analyzed by ANOVA and linear regression. RESULTS: Thermoregulatory vasoconstriction was associated with marked arterial pressure waveform changes. Radial pressure showed, in lieu of a dicrotic notch, large oscillations of decreasing amplitude. Femoral pressure showed a single diastolic oscillation of smaller amplitude. The waveforms appeared different, depending on the hydraulic coupling system used, artifact being more marked with the longer connectors. On the average, radial systolic pressure exceeded femoral systolic pressure during vasoconstriction; however, during vasodilatation, femoral systolic pressure exceeded radial systolic pressure (p < 0.05). Oscillometric measurements underestimated systolic pressure, and did so more markedly during vasoconstriction. There were no differences in the values of mean and diastolic pressures. CONCLUSION: Thermoregulatory vasoconstriction alters radial arterial pressure waveform, artifactually increasing its peak systolic pressure compared with the femoral artery. Poor dynamic responses of recording systems further distort the waveforms. Consequently, radial artery pressure may be misleading in vasoconstricted patients.

Adult↗
PubMed1993

[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.

Acute Disease↗
PubMed1992

Double-blind placebo-controlled trial of terazosin effect on blood pressure and urinary output of dopamine in hypertensive patients.

In a parallel, double-blind study, 12 untreated hypertensive patients received terazosin (2-4 mg/day for 4 weeks), and 12 received placebo during the same period. Systolic and diastolic blood pressure decreased significantly in the terazosin group, from 150 +/- 5.0 mmHg systolic and 99.6 +/- 2.0 diastolic before treatment, to 134.0 +/- 7.0 systolic and 85.6 +/- 3.0 mmHg diastolic at week 4 of treatment. No significant blood pressure changes occurred in the placebo group. Blood pressure decrease showed a positive correlation (r = .62 and r = .52 for systolic and diastolic blood pressure, respectively) with the patient's age (P less than .05). Total plasma cholesterol decreased 18% in the terazosin group (P less than .05) and 9% in the placebo group (P greater than .05). Urinary dopamine excretion decreased significantly from 692.8 +/- 180.0 to 330.5 +/- 52.0 micrograms/24 hours in the terazosin group (P less than .05) and showed a nonsignificant increase in the placebo group. Compared with 22 age- and sex-matched healthy volunteers, urinary dopamine excretion in the hypertensive group before treatment was not statistically different (779.3 +/- 83.1 micrograms/24 hours). Dopamine excretion was higher in untreated hypertensive men and in male healthy volunteers compared with women. The decrease of urinary dopamine excretion observed under terazosin treatment could be due to a decrease of kidney dopamine synthesis or release induced by blood pressure reduction, or secondarily to the blockade of kidney alpha 1-receptors, modulating dopamine excretion. No significant changes were observed in urinary excretion of noradrenaline and adrenaline.

Adrenergic alpha-Antagonists↗
PubMed1992

Renal function and cardiopulmonary bypass: effect of perfusion pressure.

Controversy continues as to whether hypotension during cardiopulmonary bypass (CPB) impairs intraoperative and postoperative renal function. Therefore, 21 patients with normal renal function (plasma creatinine less than 1.2 mg/dL, creatinine clearance greater than 70 mL/min), aged 50 to 70 years, without associated pathology, scheduled for elective coronary surgery were studied prospectively. Patients were randomized into two groups: group 1 included 14 patients whose arterial blood pressure during CPB was left untreated, and group 2 consisted of 7 patients who received phenylephrine to maintain their arterial pressure above 70 mmHg. Plasma and urine creatinine, sodium, potassium, and osmolality were measured preoperatively, intraoperatively and postoperatively. Creatinine, osmolal and free water clearances, and excreted sodium fraction were calculated. Plasma creatinine remained normal throughout the study in all patients. Creatinine clearances were similar preoperatively (101.9 +/- 36.7 in group 1 and 120.6 +/- 50.7 mL/min in group 2). In group 1, creatinine clearance decreased during CPB to 88.7 +/- 39.7 mL/min, whereas in group 2 it increased to 157.6 +/- 79.5 mL/min; the difference between groups was significant. Early postoperatively, there was no difference: 136.2 +/- 86.6 mL/min in group 1 and 100 +/- 21.4 mL/min in group 2. One week postoperatively, values were 100.5 +/- 37.9 and 101.9 +/- 18.4, respectively. There was a significant correlation between the creatinine clearance and perfusion pressure intraoperatively, but not postoperatively. Osmolal clearance also correlated with perfusion pressure intraoperatively, but it was significantly lower in the phenylephrine group postoperatively. Postoperative renal function was normal in all patients; no deleterious effect of a low arterial pressure during bypass could be identified.

Aged↗
PubMed1992

[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.

Actuarial Analysis↗
PubMed1991

Anesthesia for elective cardioversion: a comparison of four anesthetic agents.

Elective cardioversion is a short procedure performed under general anesthesia for the treatment of cardiac dysrhythmias. Selection of the anesthetic agent is important, because a short duration of action and hemodynamic stability are required. Forty-four patients scheduled for elective cardioversion in the coronary care unit were studied prospectively. All patients were randomly assigned, according to the last digit of their clinical record number, to receive one of the four anesthetic agents studied: group 1, 12 patients who received 3 mg/kg of sodium thiopental; group 2, 10 patients who received 0.15 mg/kg of etomidate; group 3, 12 patients who received 1.5 mg/kg of propofol; and group 4, 10 patients who received 0.15 mg/kg of midazolam. All patients also received 1.5 micrograms/kg of fentanyl 3 minutes before induction. All four drugs provided satisfactory anesthesia for cardioversion and there were no major complications. Midazolam produced a more prolonged duration of effect and more interindividual variability. Propofol was associated with hypotension and a higher incidence of apnea, and its duration of action was similar to that of etomidate or thiopental. Etomidate produced myoclonus and pain on injection; however, it was the only agent that did not decrease arterial blood pressure. Thiopental reduced blood pressure but otherwise seemed an appropriate anesthetic for this procedure. In conclusion, all four anesthetic agents were acceptable for cardioversion, although their pharmacological differences suggest specific indications for individual patients.

Adult↗
PubMed1990

[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.

Adolescent↗