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Biomedical subjects

I F Palacios

Publications and source records attributed to I F Palacios.

At least 73 records · Page 4Linked to original sources
PubMed1995

Coronary vascular reactivity is abnormal in patients with Chagas' heart disease.

Symptoms of myocardial ischemia, such as chest pain (sometimes with anginal features), acute myocardial infarction, and segmental wall motion abnormalities (including left ventricular apical aneurysm), frequently occur in patients with Chagas' heart disease. Because these clinical findings occur in the presence of normal coronary arteries, it is possible that an abnormality of the coronary vascular reactivity could be present in these patients. Therefore the current study was undertaken to determine whether endothelium-dependent coronary vasodilation is abnormal in Chagas' heart disease. Coronary endothelial function was assessed by infusing the endothelium-dependent vasodilator acetylcholine (10(-8) to 10(-6) mol/L) and the endothelium-independent vasodilator adenosine (10(-4) mol/L) into the left anterior descending coronary artery of nine patients (age 43 +/- 4 years) with Chagas' heart disease. Coronary blood flow was measured with a Doppler flow velocity catheter and by quantitative coronary cineangiography. The left ventricular ejection fraction was 39% +/- 5%; eight patients had a left ventricular apical aneurysm; and one had an area of anteroapical hypokinesis. An impairment of the endothelium-dependent coronary vasodilation was demonstrated by a reduction in coronary blood flow of 41.2% +/- 12.8% produced by the infusion of acetylcholine at 10(-6) mol/L and by a blunted but preserved increase in coronary blood flow of 114.6% +/- 65.0% with the infusion of adenosine at 10(-4) mol/L (p = 0.03). In conclusion, patients with Chagas' heart disease have an abnormality of the coronary endothelium-dependent vasodilation, and this abnormality may play a role in their chest pain syndrome and in the development of segmental wall motion abnormalities.

Acetylcholine↗
PubMed1995

Dynamic expansion of the coronary arteries: implications for intravascular ultrasound measurements.

The majority of coronary artery blood flow occurs in diastole; however, systolic epicardial coronary artery expansion has been described. With the advent of intravascular ultrasound, precise measurements of arterial structures with excellent spacial and temporal resolution are now readily available. However, the effect of dynamic expansion of the coronary arteries on routine intravascular ultrasound measurements has not been assessed. The purpose of this study was to determine in vivo the presence, timing, and extent of dynamic changes in the coronary arteries and saphenous vein grafts and to assess their implications for intravascular ultrasound measurements. Intravascular ultrasound images were obtained with simultaneous electrocardiographic monitoring in 202 coronary artery and 50 saphenous vein graft sites in 32 patients with varying plaque burden and morphologic features. Arterial, luminal, and plaque area were measured at end-diastole and early, mid-, and end-systole. Coronary luminal diameter increased 2.1%; luminal area increased 8.1%; arterial area increased 3.7%; and plaque area decreased 4.9% during mid and late systole (p < 0.01). There was no detectable cyclic change in saphenous vein graft dimensions. In coronary arteries there was significant systolic expansion of the artery and lumen and systolic thinning of the plaque. The magnitude of dynamic luminal area change was greater than the variability in measurement and thus warrants gating to the cardiac cycle. The lack of dynamic change in saphenous vein grafts and the relatively small dynamic change in luminal diameter and arterial and plaque areas suggest nominal utility in gating these measurements to the cardiac cycle.

Adult↗
PubMed1995

Three-dimensional intravascular ultrasound assessment of plaque volume after successful atherectomy.

The primary purpose of directional coronary atherectomy is the removal of intraluminal plaque. Angiography allows assessment of residual lumen narrowing but is limited in the assessment of residual plaque burden. Intravascular ultrasound has proven useful in assessing plaque size, but current use has been limited to a single, representative cross-sectional image rather than an evaluation of the entire plaque volume. To determine the volume of residual plaque after angiographically successful directional coronary atherectomy ( < or = 20% residual stenosis), we performed intravascular ultrasound in 19 patients before and after atherectomy. Only coronary lesions optimal for three-dimensional analysis (a single, discrete stenosis in a nontortuous, noncalcified native coronary artery) were selected. A 2.9F sheath-design intravascular ultrasound catheter with a motorized pullback device was used in all patients. The cross-sectional area of the artery (defined by the medial-adventitia border), the lumen, and the plaque were measured at 1 mm intervals over a 15 to 20 mm segment, which included the target lesion and a proximal reference segment (n = 362 cross-sections), before and after atherectomy. The volumes of the artery, vessel lumen, or plaque were calculated with a modified Simpson's equation and compared with standard area measurements at the point of maximal stenosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Platelet degranulation induced by some contrast media is independent of their nonionic vs ionic nature.

We confirm that the phenomenon of platelet degranulation exists for both iohexol and diatrizoate, as reported earlier. In contrast to previous conclusions, however, we have determined that the degranulation is independent of the nonionic vs. ionic nature of the media per se, since degranulation was neither seen with nonionic iodixanol nor ionic ioxaglate. The degranulation, further, does not significantly augment platelet function, as measured by flowing whole blood platelet aggregometry.

Blood Platelets↗
PubMed1994

The technique and safety of transseptal left heart catheterization: the Massachusetts General Hospital experience with 1,279 procedures.

With the introduction of interventional procedures such as percutaneous mitral valvuloplasty and radiofrequency ablation of left-sided bypass tracts, there has been renewed interest in the technique of transseptal left heart catheterization. We review our experience with 1,279 transseptal catheterizations performed over the last 10 years. The most common indications for transseptal catheterization included direct measurement of left atrial pressure or access to the left ventricle in patients with prosthetic aortic or mitral valves, and in patients undergoing percutaneous mitral valvuloplasty. A total of 17 major complications occurred (1.3%), including cardiac tamponade (15 patients, 1.2%), systemic emboli (1 patient, 0.08%), and death secondary to aortic perforation (0.08%). We conclude that when performed by experienced operators, transseptal left heart catheterization is associated with low morbidity and mortality.

Adolescent↗
PubMed1994

Intraventricular conduction abnormalities in patients with clinically suspected myocarditis are associated with myocardial necrosis.

Twenty-nine patients with suspected myocarditis, either with or without intraventricular conduction abnormalities, were investigated for degree of myocardial necrosis by antimyosin scintigraphy. Among those 29 patients, 16 had intraventricular conduction abnormalities. Antimyosin scans were analyzed for heart/lung ratios and semiquantitative visual uptake scores (0 to 4+ scale). Of the 16 patients with conduction abnormalities, 15 (94%) demonstrated visual antimyosin uptake versus 7 (54%) of 13 cases without conduction abnormalities (p < 0.03). In addition, the heart/lung ratios and uptake scores were significantly higher in the group with conduction abnormalities than in the group without (1.64 +/- 0.31 vs 1.39 +/- 0.20, p < 0.03; and 2.3 +/- 0.7 vs 1.4 +/- 0.7, p < 0.005; respectively). In conclusion, intraventricular conduction abnormalities in patients with suspected myocarditis were more strongly associated with active and more severe myocardial necrosis as judged by antimyosin imaging than patients with normal electrocardiograms.

Adult↗
PubMed1994

Right ventricular dysfunction: an independent predictor of adverse outcome in patients with myocarditis.

To assess the predictive value of right ventricular systolic function in patients with active myocarditis, the echocardiograms of 23 patients with biopsy-confirmed myocarditis were reviewed. Right ventricular systolic function was evaluated qualitatively and quantitatively by descent of the right ventricular base. Patients were divided into those with normal right ventricular function, in whom right ventricular descent was 1.9 +/- 0.1 cm, and those with abnormal right ventricular function, in whom right ventricular descent was 0.8 +/- 0.1 cm (p < 0.001). There were no differences between the two groups in age, duration of symptoms, baseline hemodynamics, or histologic assessment. Initial left ventricular ejection fraction was significantly lower in patients with depressed right ventricular function (27.5 +/- 4.9%) compared with that in patients with normal right ventricular function (47.5 +/- 6.3%) (p = 0.01). The likelihood of an adverse outcome, defined as death or need for cardiac transplantation, was greater in patients with abnormal right ventricular function (right ventricular descent < or = 1.7 cm) than in patients with normal right ventricular function (right ventricular descent > 1.7 cm) (p < 0.03). Multivariate analysis revealed that right ventricular dysfunction as quantified by right ventricular descent was the most powerful predictor of adverse outcome.

Female↗
PubMed1994

Significant tricuspid regurgitation is a marker for adverse outcome in patients undergoing percutaneous balloon mitral valvuloplasty.

OBJECTIVES: This study examined the association between the presence of tricuspid regurgitation and immediate and late adverse outcomes in patients undergoing balloon mitral valvuloplasty. BACKGROUND: Significant tricuspid regurgitation has an adverse impact on morbidity and mortality in patients undergoing mitral valve surgery for mitral stenosis. METHODS: We studied 318 consecutive patients (mean [+/- SD] age 54 +/- 15 years) who underwent balloon mitral valvuloplasty and had color Doppler echocardiographic studies before the procedure. Patients were classified into three groups: 221 with no or mild (69%), 60 with moderate (19%) and 37 with severe (12%) tricuspid regurgitation. Clinical follow-up ranged from 6 to 62 months. RESULTS: Before mitral valvuloplasty, increasing degrees of tricuspid regurgitation were associated with a smaller initial mitral valve area (p < 0.05), higher echocardiographic score (p < 0.05), lower cardiac output (p < 0.01) and higher pulmonary vascular resistance (p < 0.01). Although the initial success rate did not differ significantly between groups, patients with a higher degree of tricuspid regurgitation had less optimal results, as reflected by a smaller absolute increase in mitral valve area (1.02 vs. 0.9 vs. 0.7 cm2, p < 0.01). The estimated 4-year event-free survival rate (freedom from death, mitral valve surgery, repeat valvuloplasty and heart failure) was lower for the group with severe tricuspid regurgitation (68% vs. 58% vs. 35%, p < 0.0001). At 4 years, 94% of patients with mild tricuspid regurgitation were alive compared with 90% and 69%, respectively, of patients with moderate or severe tricuspid regurgitation (p < 0.0001). Cox proportional analysis identified tricuspid regurgitation as an independent predictor of late outcome (p < 0.001). CONCLUSIONS: Patients with mitral stenosis and severe tricuspid regurgitation undergoing mitral valvuloplasty have advanced mitral valve and pulmonary vascular disease, suboptimal immediate results and poor late outcome.

Adult↗
PubMed1994

Exercise capacity and systolic and diastolic ventricular function after recovery from acute dilated cardiomyopathy.

OBJECTIVES: This study was undertaken to determine whether abnormalities in exercise capacity or ventricular function persist after recovery from acute dilated cardiomyopathy. BACKGROUND: Persistent ventricular structural abnormalities could cause abnormalities in exercise capacity or ventricular function. METHODS: The results of rest and exercise first-pass radionuclide ventriculography in 18 patients who were seen within 6 months of the onset of dilated cardiomyopathy and subsequently had a normal rest left ventricular ejection fraction were compared with those of age- and gender-matched control subjects. RESULTS: Patients were studied 144 +/- 34 (mean +/- SEM) days after the onset of left ventricular dysfunction at a time when heart failure symptoms had resolved. Patients with myocyte necrosis, as assessed by endomyocardial biopsy (n = 13) or antimyosin scintigraphy (n = 12), recovered more rapidly than did those without necrosis. Oxygen consumption both at peak exercise (17.7 +/- 1.2 vs. 26.1 +/- 1.5 ml/kg per min, p < 0.05) and at the anaerobic threshold (11.1 +/- 0.5 vs. 17.1 +/- 1.3 ml/kg per min, p < 0.05) was lower in the patients who had recovered from cardiomyopathy than in control subjects. Rest and exercise end-systolic and end-diastolic left ventricular volumes were greater in the patients than in the control subjects, although stroke volumes were similar. Left ventricular filling at rest was lower at diastolic filling intervals of 40% and 90%, and rest and exercise left ventricular early peak filling rate normalized for end-diastolic volume was slower in the patients than in the control subjects. At long-term follow-up of 1,082 +/- 206 days, two patients had a return of heart failure symptoms and a decrease in left ventricular ejection fraction. CONCLUSIONS: Despite the apparent normalization of rest left ventricular ejection fraction, patients who have recovered from dilated cardiomyopathy have abnormalities in aerobic exercise capacity and in left ventricular systolic and diastolic performance.

Acute Disease↗
PubMed1994

The role of percutaneous aortic balloon valvuloplasty in patients with cardiogenic shock and critical aortic stenosis.

OBJECTIVES: The goal of this study was to evaluate the role of percutaneous aortic valvuloplasty in patients with cardiogenic shock due to severe aortic stenosis and associated major comorbid conditions and to establish predictors of survival. BACKGROUND: The prognosis for patients in cardiogenic shock with severe aortic stenosis is poor. Aortic valve replacement can be lifesaving, but the presence of multiorgan failure precludes these patients from operation. Percutaneous aortic balloon valvuloplasty has been used in these patients with short-term improvement and could be an alternative therapeutic option. METHODS: Of 310 patients undergoing percutaneous aortic balloon valvuloplasty, 21 were in cardiogenic shock and were included in this study. All 21 patients had associated major comorbid conditions at the time of presentation. RESULTS: After percutaneous aortic balloon valvuloplasty, systolic aortic pressure increased from 77 +/- 3 (mean +/- SEM) to 116 +/- 8 mm Hg (p = 0.0001); aortic valve area increased from 0.48 +/- 0.04 to 0.84 +/- 0.06 cm2 (p = 0.0001); and cardiac index increased from 1.84 +/- 0.13 to 2.24 +/- 0.15 liters/min per m2 (p = 0.06). Nine patients died in the hospital, two during the procedure and seven after successful percutaneous aortic balloon valvuloplasty (five from multiorgan failure). Five patients had vascular complications. Stroke, cholesterol emboli and aortic regurgitation requiring aortic valve replacement occurred in one patient each. Twelve patients (57%) survived and were followed up for 15 +/- 6 months; five patients subsequently died. The Kaplan-Meier survival curve showed a 38 +/- 11% survival rate at 27 months. The only predictor for longer survival rate was the postprocedure cardiac index. CONCLUSIONS: 1) Emergency percutaneous aortic balloon valvuloplasty can be performed successfully as a lifesaving procedure. 2) Morbidity and mortality remain high despite successful percutaneous aortic balloon valvuloplasty. 3) For nonsurgical candidates, percutaneous aortic balloon valvuloplasty may be the only therapeutic alternative.

Adult↗
PubMed1994

Percutaneous mitral balloon valvotomy in patients with calcific mitral stenosis: immediate and long-term outcome.

OBJECTIVES: This study analyzed the immediate and long-term outcome of percutaneous balloon mitral valvotomy in patients with and without fluoroscopically visible mitral valve calcification. BACKGROUND: Mitral valve calcification has been shown to be an important factor in determining immediate and long-term outcome of patients undergoing surgical mitral commissurotomy. Patient selection has an important impact on the outcome of percutaneous balloon mitral valvotomy. METHODS: The immediate and long-term results of percutaneous balloon mitral valvotomy were compared in 155 patients with and 173 patients without mitral valve calcification. The patients with calcified valves were assigned to four groups according to severity of calcification. RESULTS: Patients with calcified mitral stenosis more frequently were in New York Heart Association functional class III or IV and more frequently had atrial fibrillation, previous surgical commissurotomy, echocardiographic score > 8, higher pulmonary artery and left atrial pressures, higher pulmonary vascular resistance and mean mitral valve gradient and lower cardiac output and smaller mitral valve area. Mitral valve area after valvotomy was significantly smaller in patients with calcified valves (1.8 +/- 0.06 vs. 2.1 +/- 0.06 cm2) and was > or = 1.5 cm2 in 65% of patients with and 83% of patients without calcified valves (p = 0.004). A successful outcome, defined as mitral valve area > 1.5 cm2 without significant mitral regurgitation and left to right shunting, was achieved in 52% of patients with and 69% of patients without uncalcified valves (p = 0.001). The success rate was 59%, 48%, 35% and 33% in subgroups with 1+, 2+, 3+ and 4+ calcification, respectively. The rates of significant left to right shunting and mitral regurgitation after valvuloplasty were similar in the two groups. Estimated survival rate (80% vs. 99%, respectively, p = 0.0001), survival rate without mitral valve replacement (67% vs. 93%, respectively, p < 0.00005) and event-free survival rate (63% vs. 88%, respectively, p < 0.00005) at 2 years were significantly better in the patients with uncalcified valves. Survival rate curves became progressively worse as the severity of calcification increased. CONCLUSIONS: These findings indicate that immediate and long-term results of mitral valvuloplasty are not as successful in patients with fluoroscopically visible mitral valve calcification as in those without calcification.

Calcinosis↗
PubMed1994

Percutaneous mitral balloon valvotomy for patients with mitral stenosis.

This study reports the immediate outcome, in-hospital complications, and long-term clinical follow-up of patients undergoing percutaneous mitral balloon valvotomy. In most series, this procedure is reported to increase mitral valve area from less than 1.0 cm2 to at least 2.0 cm2. The most important predictor of the immediate outcome of percutaneous mitral valvotomy is the echocardiographic score. The best results with percutaneous mitral valvotomy occur in those patients with echocardiographic scores of 8 or less. Mortality and morbidity with percutaneous mitral valvotomy are low and similar to surgical commissurotomy. There is less than 1% mortality, a 0% to 3.1% incidence of thromboembolic episodes and stroke, a 1% to 5.2% incidence of severe mitral regurgitation, a 0.2% to 4.1% incidence of pericardial tamponade, and a 3% to 16% incidence of left-to-right shunt. Survival (83 +/- 6% vs 48 +/- 8%), survival with freedom from mitral valve surgery (58 +/- 5% vs 25 +/- 5%), and event-free survival (51 +/- 6% vs 22 +/- 5%) at 80-month follow-up was greater in patients with echocardiographic scores of 8 or less compared with those with scores greater than 8 (P < 0.0001). Thus, the excellent immediate and long term results of percutaneous mitral valvotomy in patients with echocardiographic scores of 8 or less suggest that this procedure may be the treatment of choice in this group of patients.

Balloon Occlusion↗
PubMed1994

Macrophage infiltration in acute coronary syndromes. Implications for plaque rupture.

BACKGROUND: Rupture of atherosclerotic plaques is probably the most important mechanism underlying the sudden onset of acute coronary syndromes. Macrophages may release lytic enzymes that degrade the fibrous cap and therefore produce rupture of the atherosclerotic plaque. This study was designed to quantify macrophage content in coronary plaque tissue from patients with stable and unstable coronary syndromes. METHODS AND RESULTS: Hematoxylin and eosin and immunostaining with anti-human macrophage monoclonal antibody (PG-M1) were performed. Computerized planimetry was used to analyze 26 atherectomy specimens comprising 524 pieces of tissue from 8 patients with chronic stable angina, 8 patients with unstable angina, and 10 patients with non-Q-wave myocardial infarction. Total plaque area was 417 +/- 87 mm2 x 10(-2) in patients with stable angina, 601 +/- 157 mm2 x 10(-2) in patients with unstable angina, and 499 +/- 87 mm2 x 10(-2) in patients with non-Q-wave myocardial infarction (P = NS). The macrophage-rich area was larger in plaques from patients with unstable angina (61 +/- 18 mm2 x 10(-2)) and non-Q-wave myocardial infarction (87 +/- 32 mm2 x 10(-2)) than in plaques from patients with stable angina (14 +/- 5 mm2 x 10(-2)) (P = .024). The percentage of the total plaque area occupied by macrophages was also larger in patients with unstable angina (13.3 +/- 5.6%) and non-Q-wave myocardial infarction (14.6 +/- 4.6%) than in patients with stable angina (3.14 +/- 1%) (P = .018). Macrophage-rich sclerotic tissue was largest in patients with non-Q-wave myocardial infarction (67 +/- 30 mm2 x 10(-2)) and unstable angina (55 +/- 19 mm2 x 10(-2)) than in patients with stable angina (11.5 +/- 4.1 mm2 x 10(-2)) (P = .046). Macrophage-rich atheromatous gruel was also largest in patients with non-Q-wave myocardial infarction (15 +/- 4 mm2 x 10(-2)) than in patients with unstable angina (3.3 +/- 1.7 mm2 x 10(-2)) or stable angina (2.4 +/- 1.2 mm2 x 10(-2)) (P = .026). CONCLUSIONS: Macrophage-rich areas are more frequently found in patients with unstable angina and non-Q-wave myocardial infarction. This suggests that macrophages are a marker of unstable atherosclerotic plaques and may play a significant role in the pathophysiology of acute coronary syndromes.

Aged↗
PubMed1994

Significant tricuspid regurgitation does not resolve after percutaneous balloon mitral valvotomy.

A total of 318 consecutive patients with mitral stenosis underwent percutaneous mitral valvotomy at our institution from 1987 to 1993. Of those, 98 patients had color Doppler echocardiographic studies performed before, 24 hours after, and late after the intervention. On the basis of color Doppler echocardiographic grading of tricuspid regurgitation, 32 patients (32%; mean age 57 +/- 15 years) had significant (moderate or severe) tricuspid regurgitation before the intervention and were the subject of this study. The follow-up study was performed 18.4 +/- 13 months after the procedure. Successful percutaneous mitral valvotomy (> or = 1.5 cm2 valve area or > or = 50% increase after valvotomy) with no restenosis at follow-up was achieved in 20 patients. Tricuspid regurgitation decreased by one grade (from severe to moderate) in only four subjects in this group and in none of the 12 patients who did not meet the criteria for successful percutaneous mitral valvotomy or who had restenosis. Thus tricuspid regurgitation did not improve in 88% of all patients studied. On average, no significant change was observed in the ratio of maximal tricuspid regurgitant jet area to right atrial area 24 hours after percutaneous mitral valvotomy and at late follow-up (37% vs .33% vs 34%, respectively) or in any of the right heart dimensions, even in patients who underwent successful percutaneous mitral valvotomy. Right ventricular systolic pressure also did not change significantly on average in those patients (46 +/- 15 versus 42 +/- 14 versus 48 +/- 18 mm Hg, respectively). However, right ventricular dimensions did not decrease and tricuspid regurgitation did not resolve even in a subgroup of patients in whom right ventricular systolic pressure fell by more than 10 mm Hg (up to 41 mm Hg).

Aged↗
PubMed1993

Early decrease in minimal luminal diameter after successful percutaneous transluminal coronary angioplasty predicts late restenosis.

Eighty-eight patients underwent serial coronary arteriography before, immediately after, 24 hours after and 7 +/- 2 months after successful percutaneous transluminal coronary angioplasty (PTCA) of 102 lesions. Severity of coronary obstruction was measured using quantitative digital angiography. Three groups of lesions were defined when comparing angiograms recorded immediately after and 24 hours after PTCA: group I--lesions with either no change or < or = 10% increase in arterial diameter stenosis after PTCA (n = 71); group II--lesions with > 10% increase in diameter stenosis after PTCA (n = 19); and group III--patients with total occlusion (n = 12). There were no significant differences in the severity of stenosis before or immediately after PTCA among the 3 groups of lesions. Twenty-four hours after PTCA the diameter stenosis was 14.2 +/- 6.3% in group I, 34.7 +/- 8.1% in group II and 100 in group III (p < 0.0001). At 7.1 +/- 2 months after PTCA the diameter stenosis was 21.2 +/- 16.8% in group I, 61.3 +/- 1.1% in group II, and 98.5 +/- 1.3% in group III (p < 0.0001). Restenosis (> or = 50% stenosis diameter) at follow-up per lesion was significantly greater in group II than in group I (73.6 vs 9.8%) (p < 0.0001). Thus, early angiographic study after successful PTCA stratifies lesions into angiographic subsets with low (group I) and high (group II) risk of coronary restenosis.

Adult↗