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Biomedical subjects

D N Salem

Publications and source records attributed to D N Salem.

At least 19 recordsLinked to original sources
PubMed1992

Direct angioplasty for acute myocardial infarction. A review of outcomes in clinical subsets.

PURPOSE: To review the usefulness of angioplasty done early in the course of an acute myocardial infarction without preceding thrombolytic therapy. DATA SOURCES: The English-language literature was searched from 1983 through October 1991 using MEDLINE; bibliographies from selected articles were searched by hand. STUDY SELECTION: Series reporting results for direct angioplasty without preceding thrombolytic therapy were reviewed. Twenty-three articles describing a total of 4368 patients were found. DATA EXTRACTION: After duplicate patient series were eliminated, weighted average short- and long-term mortality rates were calculated for the remaining 2073 patients in 10 series and for selected clinical subsets. RESULTS OF DATA SYNTHESIS: Average hospital mortality for patients with acute myocardial infarction having direct angioplasty was 8.3% (95% Cl, 7.1% to 9.5%). Patients in cardiogenic shock had the highest mortality (44.2%; Cl, 35.9% to 52.5%); patients with one-vessel disease had the lowest (1%; Cl, 0% to 2.3%). For patients in cardiogenic shock, data on direct angioplasty appeared superior to data for similar patients receiving thrombolytic therapy. Although few data exist, a survival advantage was also suggested for patients with a history of previous bypass surgery (hospital mortality, 11.1% [Cl, 4.4% to 17.8%]). CONCLUSIONS: Direct angioplasty has an overall mortality similar to that of thrombolytic therapy. Patients who may benefit more from mechanical revascularization than from thrombolytic therapy include those at increased risk for thrombolytic therapy (uncontrolled hypertension, recent major surgery, cerebrovascular accident, prolonged cardiopulmonary resuscitation, or bleeding diathesis), and those with cardiogenic shock. The efficacy in several other patient subsets (age greater than 65 years, previous coronary artery bypass grafting, prolonged delay before reperfusion) warrants further study.

Angioplasty, Balloon, Coronary↗
PubMed1992

Lipoprotein cholesterol, apolipoprotein A-I and B and lipoprotein (a) abnormalities in men with premature coronary artery disease.

The prevalence of abnormalities of lipoprotein cholesterol and apolipoproteins A-I and B and lipoprotein (a) [Lp(a)] was determined in 321 men (mean age 50 +/- 7 years) with angiographically documented coronary artery disease and compared with that in 901 control subjects from the Framingham Offspring Study (mean age 49 +/- 6 years) who were clinically free of coronary artery disease. After correction for sampling in hospital, beta-adrenergic medication use and effects of diet, patients had significantly higher cholesterol levels (224 +/- 53 vs. 214 +/- 36 mg/dl), triglycerides (189 +/- 95 vs. 141 +/- 104 mg/dl), low density lipoprotein (LDL) cholesterol (156 +/- 51 vs. 138 +/- 33 mg/dl), apolipoprotein B (131 +/- 37 vs. 108 +/- 33 mg/dl) and Lp(a) levels (19.9 +/- 19 vs. 14.9 +/- 17.5 mg/dl). They also had significantly lower high density lipoprotein (HDL) cholesterol (36 +/- 11 vs. 45 +/- 12 mg/dl) and apolipoprotein A-I levels (114 +/- 26 vs. 136 +/- 32 mg/dl) (all p less than 0.005). On the basis of Lipid Research Clinic 90th percentile values for triglycerides and LDL cholesterol and 10th percentile values for HDL cholesterol, the most frequent dyslipidemias were low HDL cholesterol alone (19.3% vs. 4.4%), elevated LDL cholesterol (12.1% vs. 9%), hypertriglyceridemia with low HDL cholesterol (9.7% vs. 4.2%), hypertriglyceridemia and elevated LDL cholesterol with low HDL cholesterol (3.4% vs. 0.2%) and Lp(a) excess (15.8% vs. 10%) in patients versus control subjects, respectively (p less than 0.05). Stepwise discriminant analysis indicates that smoking, hypertension, decreased apolipoprotein A-I, increased apolipoprotein B, increased Lp(a) and diabetes are all significant (p less than 0.05) factors in descending order of importance in distinguishing patients with coronary artery disease from normal control subjects. Not applying a correction for beta-adrenergic blocking agents, sampling bias and diet effects leads to a serious underestimation of the prevalence of LDL abnormalities and an overestimation of HDL abnormalities in patients with coronary artery disease. However, 35% of patients had a total cholesterol level less than 200 mg/dl after correction; of those patients, 73% had an HDL cholesterol level less than 35 mg/dl.

Apolipoproteins↗
PubMed1992

Intracardiac echocardiography during simulated aortic and mitral balloon valvuloplasty: in vivo experimental studies.

The feasibility of intracardiac echocardiography with a low-frequency transducer to assess catheter position and detect complications during experimental aortic and mitral balloon valvuloplasty was studied in 10 dogs. Intracardiac echocardiography was performed with a transesophageal echocardiographic probe placed in the right atrium. In all instances high-quality images of cardiac structures were obtained. The guide wire and balloon catheter were clearly seen as they crossed the valves. With inflation the balloon was seen as a hyperechoic structure. Doppler echocardiography documented aortic regurgitation after inflations. Acute pericardial effusion was instantly detected. It is concluded that intracardiac echocardiography is a potentially useful technique for cardiac imaging, assessing wire and balloon catheter position, evaluating valvular regurgitation, and instantly detecting acute pericardial effusion. Further research in humans with low-frequency, catheter-based transducers needs to be performed.

Animals↗
PubMed1992

The MspI restriction fragment length polymorphism 3' to the apolipoprotein A-II gene: relationships with lipids, apolipoproteins, and premature coronary artery disease.

In previous studies, a restriction fragment length polymorphism (RFLP) has been identified using MspI restriction endonuclease in the 3' region of the apo A-II gene. The rare variant site for this MspI (M2) has been reported to be associated with higher levels of HDL cholesterol and apo A-II. We have studied the frequency and lipid associations of this RFLP in a population of 168 coronary artery disease (CAD) male and female patients, who had more than 50% narrowing of one or more arteries prior to age 60 years, as well as 255 aged-matched males and females from the Framingham Offspring Study. We also studied 31 kindreds in which the proband had premature CAD. The frequency of the M2 allele was higher in CAD cases (0.20) than in the controls (0.13) (P less than 0.05). In general, those subjects carrying the M2 allele had lower HDL cholesterol and apo A-I plasma levels; however, this difference was only significant (P less than 0.02 and 0.002, respectively) in females with CAD. No cosegregation of the M2 allele with hypoalphalipoproteinemia was found in 31 kindreds studied. However, in both generations there was a trend for those subjects carrying the M2 allele to have lower HDL cholesterol levels than those carrying the M1 allele. Sequence analysis of the apo A-II gene of subjects homozygous for either the M1 (n = 1) or the M2 allele (n = 2) revealed that this RFLP is due to a T----C single base mutation 528 bp 3' to the apo A-II gene. In the subjects homozygous for the M2 allele no other mutations were found within the coding region of the apo A-II gene that could result in changes in the primary sequence of the protein. These data indicate that the MspI RFLP 3' to the apo A-II gene is somewhat more frequent in the CAD group. However, there was no significant association between this RFLP and any of the parameters examined. In conclusion, this DNA marker lacks the specificity to be clinically useful for CAD risk assessment in the population studied.

Adult↗
PubMed1992

Familial lipoprotein disorders in patients with premature coronary artery disease.

BACKGROUND: Genetic lipoprotein disorders have been associated with premature coronary artery disease (CAD). METHODS AND RESULTS: The prevalence of such disorders was determined in 102 kindreds (n = 603 subjects) in whom the proband had significant CAD documented by angiography before the age of 60 years. Fasting plasma cholesterol, triglyceride, low density lipoprotein (LDL) cholesterol, apolipoprotein (apo) B, and lipoprotein (a) [Lp(a)] values above the 90th percentile and high density lipoprotein (HDL) cholesterol and apo A-I below the 10th percentile of age- and sex-specific norms were defined as abnormal. An abnormality was noted in 73.5% of probands compared with 38.2% in age-matched controls (p less than 0.001), with a low HDL cholesterol level (hypoalphalipoproteinemia) being the most common abnormality (39.2% of cases). In these kindreds, 54% had a defined phenotypic familial lipoprotein or apolipoprotein disorder. The following frequencies were observed: Lp(a) excess, 18.6% (includes 12.7% with no other dyslipidemias); hypertriglyceridemia with hypoalphalipoproteinemia, 14.7%; combined hyperlipidemia, 13.7% (11.7% with and 2.0% without hypoalphalipoproteinemia); hyperapobetalipoproteinemia (elevated apo B only), 5%; hypoalphalipoproteinemia, 4%; hypercholesterolemia (elevated LDL only), 3%; hypertriglyceridemia, 1%; decreased apo A-I only, 1%. Overall, 54% of the probands had a familial dyslipidemia; unclassifiable lipid disorders (spouse also affected) were found in 3%. No identifiable familial dyslipidemia was noted in 43% of kindreds of those; nearly half (45%) had a sporadic lipid disorder. Parent-offspring and proband-spouse correlations for these biochemical variables revealed that lipoprotein and apolipoprotein levels are in part genetically determined, with Lp(a) showing the highest degree of parent-offspring correlation. CONCLUSIONS: Our data indicate that more than half of patients with premature CAD have a familial lipoprotein disorder, with Lp(a) excess, hypertriglyceridemia with hypoalphalipoproteinemia, and combined hyperlipidemia with hypoalphalipoproteinemia being the most common abnormalities.

Coronary Disease↗
PubMed1991

Prevalence of risk factors in men with premature coronary artery disease.

The prevalence of modifiable cardiovascular risk factors (systemic hypertension, diabetes mellitus, cigarette smoking, low-density lipoprotein [LDL] cholesterol greater than or equal to 160 mg/dl and high-density lipoprotein [HDL] cholesterol less than 35 mg/dl) was determined in 321 men less than 60 years of age (mean +/- standard deviation 50 +/- 7) with premature coronary artery disease (CAD) documented at coronary angiography. The prevalence of these risk factors was markedly different than in the Framingham Offspring Study population, used here as a comparison group. In the patients with CAD, only 3% had no risk factor (other than male sex), compared with 31% in the Framingham Offspring Study subjects. Most patients with CAD (97%) had greater than or equal to 1 additional risk factor. When the patients with CAD were divided by age groups (40 to 49 years [n = 109], 50 to 59 [n = 191]), no significant differences were observed in the prevalence of risk factors between the young and older patients. The prevalence of systemic hypertension (41 vs 19%, p less than 0.001), diabetes mellitus (12 vs 1.1%, p less than 0.001), cigarette smoking (67 vs 28%, p less than 0.001) and HDL cholesterol less than 35 mg/dl (63 vs 19%, p less than 0.001) was markedly higher in the patients with CAD than in Framingham Offspring Study subjects, whereas the prevalence of LDL cholesterol greater than or equal to 160 mg/dl was not significantly different between patients with CAD and Framingham Offspring Study subjects (26 vs 26%).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Intracardiac echocardiography: current developments.

Intracardiac echocardiography refers to the method of imaging cardiac structures from intracardiac locations with the use of ultrasound catheters. Advances in catheter-based interventional cardiologic procedures to treat cardiovascular lesions and the problems encountered during those procedures due to inadequate guidance provided by fluoroscopy have given the impetus to develop other guidance modalities. Experimental explorations with intracardiac ultrasound probes have indicated that detailed visualization of cardiac structures in real-time is possible by intracardiac ultrasound. Recent advances in catheter-based ultrasound technology make it feasible to safely pass small-sized catheters in humans into various intracardiac locations and acquire images of valvular structures and various chambers. Experience with 20 MHz ultrasound catheters indicates that high resolution images of normal and abnormal structures can be obtained if the catheter is manipulated close to the region of interest. The problem of the limited depth of field associated with 20 MHz catheters has led to the fabrication of catheters with lower frequency ultrasound elements. Experimental and clinical experience with 12.5 MHz ultrasound catheters points to the capability and potential of intracardiac echocardiography to not only display normal structures but also aid in the identification of valvular abnormalities, chamber dysfunction and pericardial effusions. In addition, aortic disorders such as acute dissection, coarctation and atherosclerotic disease could be delineated. Similarly, abnormalities involving the pulmonary arteries such as pulmonary embolism, organized thrombi, peripheral pulmonary arterial stenoses, and pulmonary hypertension-induced vascular changes could be recognized. Many modifications in the catheter design are being explored. With further work in the area of catheter technology and ultrasound image processing, intracardiac echocardiography is likely to become a clinical tool.

Animals↗
PubMed1990

Myocardial revascularization for chronic stable angina. Analysis of the role of percutaneous transluminal coronary angioplasty based on data available in 1989.

No prospective, randomized clinical trial comparing coronary artery bypass grafting, percutaneous transluminal coronary angioplasty, and conservative therapy has been reported. To address when revascularization is indicated, we constructed a decision analytic model. Our model incorporates procedure-related mortality and morbidity, coronary artery disease-related mortality, and the benefit of revascularization. We determined the quality-adjusted life expectancy and expected costs for each strategy. Our model suggests that angioplasty is a reasonable alternative to bypass surgery in patients with favorable lesions if angioplasty would provide a comparable degree of revascularization. Our model predicts that patients treated with angioplasty will have more revascularization procedures than will patients treated with bypass surgery but predicts that both treatments will cost the same over the typical patient's lifetime. In many patients with severe angina or documented ischemia, angioplasty is indicated for stenosis of a single artery. In patients with two vessel disease that is amenable to angioplasty, angioplasty may be a reasonable alternative to bypass surgery. Even in patients whose three vessel disease can be completely revascularized by angioplasty, bypass surgery, although relatively expensive, is slightly better than angioplasty. In patients with three vessel disease and comorbidities that increase operative risk, angioplasty may be a reasonable alternative to either bypass surgery or medical therapy.

Angina Pectoris↗
PubMed1990

Real-time intravascular ultrasound imaging in humans.

The capability of obtaining cross-sectional, high resolution images of arteries with the use of ultrasound catheters has recently been demonstrated in animal studies. In this study the in vivo feasibility of intravascular ultrasound imaging in humans was evaluated. In 26 patients who had undergone diagnostic cardiac catheterization or iliofemoral arteriography, 1 of 3 different models of 20-MHz ultrasound catheters was advanced retrograde, into the iliac arteries and aorta or anterograde into the femoral arteries and real-time cross-sectional images of the arteries were obtained in all. In 10, the iliac arteries were normal and appeared circular and pulsatile with a 3-layered wall and crisply defined lumens. In 7 patients with nonobstructive plaques, the plaque was easily identified in the ultrasound image as a linear, bright, adynamic echo-dense structure. In 4 with obstructive disease in the iliac artery, the arterial lumen appeared irregular, bordered by a thickened, nonpulsatile wall. Variable grades of atheromatous abnormalities in the wall could be visualized. In all 5 patients with arteriographic evidence of obstructive disease of the femoral artery, intravascular ultrasound displayed reduced lumens and irregular borders with protruding high-intensity echoes in the wall. In all patients, the arterial lumen and the normal or abnormal wall were well visualized in the ultrasound images. There were no complications. This study thus demonstrates the feasibility of intravascular ultrasound imaging of arterial circulation in humans. With further improvements in catheter design and image quality, this imaging approach is likely to have a number of potential applications in the assessment of peripheral and coronary arterial diseases and in guiding interventional therapeutic procedures.

Aorta, Abdominal↗
PubMed1990

DNA polymorphisms of the apolipoprotein B gene in patients with premature coronary artery disease.

Elevated plasma levels of low density cholesterol and their major apolipoprotein (apo B) are associated with an increased risk of coronary artery disease (CAD). We have examined allele frequencies of restriction fragment length polymorphisms (RFLP) of the apo B gene in 111 male Caucasians with premature CAD (mean age 49 +/- 7 years) and in 122 elderly Caucasian males (mean age, 73 +/- 5 years), free of clinical cardiovascular disease. The rare allele (R1) of the EcoR1 RFLP in exon 29, resulting in an amino acid change (Glu----Lys4154) was seen more frequently in CAD than in controls (0.270 vs 0.207, P less than 0.05). The R1 RFLP and the MspI insertion polymorphisms (MI) within the 3' hypervariable region (HVR) were observed together in 87% and are likely in linkage disequilibrium. The MI RFLP were slightly more frequent in CAD than control (0.239 vs. 0.211, P = 0.08). A second MspI RFLP in exon 26 results in an amino acid change (Arg----Glu3611); the rare allele M2 was seen more frequently in patients than in controls (0.150 vs. 0.057, P less than 0.005). No significant differences in allele frequencies were observed for the Xba1 RFLP in exon 26 (0.500 vs. 0.529, P = ns) or for the PvuII RFLP near the 5' end (P2) (0.105 vs. 0.088, P = ns). No statistically significant differences in lipid, lipoprotein cholesterol or apolipoproteins A-I and B were observed in patients or in controls. Two of the RFLPs examined (R1 and M2) result in changes in amino acid sequence and their allele frequencies are increased in CAD cases when compared with controls. Genetic variability within the apo B gene may thus contribute to cardiovascular risk. The physiological effects of individual mutations within apo B remain to be determined. It is unlikely, however that the single site polymorphisms examined in this study, will impart further information about CAD risk than conventional lipid parameters.

Adult↗
PubMed1990

Plasma homocyst(e)ine levels in men with premature coronary artery disease.

Plasma homocyst(e)ine (that is, the sum of free and bound homocysteine and its oxidized forms, homocystine and homocysteine-cysteine mixed disulfide) levels were determined in 170 men (mean age +/- SD 50 +/- 7 years) with premature coronary artery disease diagnosed at coronary angiography and in 255 control subjects clinically free of coronary artery disease (mean age 49 +/- 6 years). Patients with coronary artery disease had a higher homocyst(e)ine level than control subjects (13.66 +/- 6.44 versus 10.93 +/- 4.92 nmol/ml, p less than 0.001). High density lipoprotein (HDL) cholesterol levels were lower (32 +/- 10 versus 46 +/- 13 mg/dl, p less than 0.001) and triglycerides levels were higher (193 +/- 103 versus 136 +/- 106 mg/dl, p less than 0.001) in the coronary disease group. Plasma total cholesterol and low density lipoprotein (LDL) cholesterol levels were not significantly different between patients with coronary disease and control subjects. The presence of hypertension, smoking or diabetes mellitus did not significantly alter homocyst(e)ine levels in the patient or the control group. Patients who were not taking a beta-adrenergic blocking drug (n = 70) had a nonsignificantly higher homocyst(e)ine level than did patients taking this class of drugs (n = 100) (14.67 +/- 8.92 versus 12.95 +/- 3.77 nmol/ml, p = 0.087). By design, none of the control subjects were taking a beta-blocker. No significant correlations were observed between homocyst(e)ine and age, serum cholesterol, LDL cholesterol, HDL cholesterol or triglyceride levels. It is concluded that an elevated plasma homocyst(e)ine level is an independent risk factor for the development of premature coronary atherosclerosis in men.

Cholesterol↗
PubMed1990

Intracardiac, intravascular, two-dimensional, high-frequency ultrasound imaging of pulmonary artery and its branches in humans and animals.

Intravascular ultrasound imaging is a promising new method for assessing vascular morphology. We evaluated the capability of intravascular ultrasound to quantify pulmonary artery (PA) morphology in vitro and explored the feasibility of in vivo PA imaging in animals and humans. In the in vitro study of 15 PA segments, we used a 20-MHz prototype ultrasound catheter. Intravascular ultrasound (y) provided crisp images of PA segments and demonstrated excellent correlations with anatomic measurements (x) in the estimation of luminal area (y = 0.89x + 2.95, r = 0.99, p less than 0.001), luminal diameter (n = 30, y = 0.79x + 0.96, r = 0.92, p less than 0.001), and vessel wall thickness (n = 60, y = 0.65x + 0.33, r = 0.85, p less than 0.001). We subsequently introduced the probe into the PA of 10 dogs and were able to obtain real-time, two-dimensional images of the main PA, its major branches, and farther smaller branches as far as the wedge level. To evaluate the in vivo feasibility of PA imaging in conscious humans, we used a commercially available, 20-MHz intravascular ultrasound (IVUS) catheter in 22 subjects through a femoral or jugular venous sheath at the end of standard diagnostic cardiac catheterization. In 20 subjects, we acquired dynamic, high-resolution, cross-sectional images of the proximal and distal PA. Changes in shape and decreasing luminal area could be clearly recognized as the IVUS catheter reached branching points and as it passed more distally. There were no complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

Left ventricular inotropic effect of atrial pacing after coronary artery bypass grafting.

The effect of atrial pacing on left ventricular (LV) performance was studied in 19 patients, 24 hours after coronary artery bypass grafting (CABG). LV volumes were calculated from simultaneous radionuclide-thermodilution measurements at rest (heart rate 82 +/- 12 beats/min), 10 minutes after the start of atrial pacing (100 beats/min), and with atrial pacing plus volume loading to return preload toward baseline. Atrial pacing reduced preload as reflected by LV end-diastolic volume index (69 +/- 14 vs 60 +/- 14 ml/m2, mean +/- standard deviation) (p less than 0.0001), but returned to baseline with volume loading. Afterload, as reflected by arterial end-systolic pressure, did not change with atrial pacing (63 +/- 9 at baseline vs 64 +/- 8 mm Hg with pacing, difference not significant). Afterload increased with volume loading (68 +/- 10 mm Hg, p less than 0.025 vs baseline and pacing). LV stroke volume decreased with atrial pacing due to reduced preload, but returned to baseline with volume loading. Cardiac index increased with atrial pacing and increased further with volume loading. Compared with baseline, LV end-systolic volume index was reduced during atrial pacing both before and after volume loading, despite unchanged or augmented afterload. The combination of atrial pacing and volume loading resulted in augmentation of LV stroke work, despite no increase in preload compared with baseline. Thus, after CABG, increased (paced) heart rate augments inotropic state, as indicated by reduced LV end-systolic volume under conditions of unchanged or increased afterload, and elevated LV stroke work without an increase in preload or a decrease in afterload.

Aged↗
PubMed1989

Dipyridamole thallium-201 imaging pre- and post-coronary angioplasty for assessment of regional myocardial ischemia in humans.

To examine the effect of coronary angioplasty on myocardial perfusion and to examine anatomic correlates of dipyridamole-thallium images, we performed dipyridamole thallium scanning before and after 24 angioplasty procedures in 23 patients with clinical ischemia. Dipyridamole thallium tomography was performed 1 to 4 (mean +/- S.D. 1.5 +/- 0.9) days before and 1 to 25 (6.3 +/- 6.9) days after angioplasty. Coronary angioplasty was anatomically successful (less than 50% residual stenosis) in 23 of 24 patients. Before angioplasty, 3 of 24 scans were interpreted as normal, with no change in these patients following angioplasty. Prior to angioplasty, 19 scans showed redistribution. After successful coronary angioplasty in 18 of 19, 17 showed improvement in dipyridamole thallium scanning; one did not show improvement and later required repeat coronary dilatation. In one patient with failed angioplasty, images before and after angioplasty were unchanged. Nine scans showed "fixed" defects before angioplasty, with improvement in three of nine following angioplasty. Quantitative analysis of the dipyridamole thallium scans revealed significant improvement in uptake in the myocardial regions supplied by the successfully dilated artery (involved regions), but not in the remote (uninvolved) regions. We conclude that myocardial perfusion, as judged by dipyridamole thallium scanning, almost always improves following anatomically successful coronary angioplasty. "Fixed" defects may improve following angioplasty and presumably represent ischemia with incomplete redistribution, rather than infarction.

Adult↗