Showing papers by "Cardiovascular Institute of the South published in 1994"

Lewis A. Conner Memorial Lecture. Mechanisms leading to myocardial infarction: insights from studies of vascular biology.

Abstract: Myocardial infarction is the most frequent cause of mortality in the United States as well as in most western countries. In this review, the processes leading to myocardial infarction are described based on the most recent studies of vascular biology; in addition, evolving strategies for prevention are outlined. The following was specifically discussed. (1) Five phases of the progression of coronary atherosclerosis (phases 1 to 5) and eight morphologically different lesions (types I, II, III, IV, Va, Vb, Vc, and VI) in the various phases are defined. (2) The present understanding of the pathogenesis of each of the phases of progression and of the various lesion types preceding myocardial infarction is described; particular emphasis is placed on the physical, structural, cellular, and chemical characteristics of the "vulnerable or unstable plaques" prone to disruption (types IV and Va lesions). (3) The fate of plaque disruption (type VI lesion) in the genesis of the various coronary syndromes and especially acute myocardial infarction is defined; particular emphasis is placed on the combination of plaque disruption and a high thrombogenic risk profile--local factors (ie, degree of plaque disruption, exposure of lipid-macrophage-rich plaque, etc) and systemic factors (ie, catecholamines, RAS, fibrinogen, etc)--in the genesis of myocardial infarction. (4) Strategies of regression or stabilization of "vulnerable or unstable plaques" for prevention of myocardial infarction are presented within the context of recent favorable experience with risk factor modification and lipid-modifying angiographic trials, beta-blockade and angiotensin-converting enzyme inhibition, antithrombotic strategies, and the possible role of estrogens. The recent past has been very fruitful in yielding a better understanding of the processes leading to myocardial infarction, and the near future appears very promising in terms of preventing the number 1 killer in the western world.

The Relationship of Dietary Animal Protein and Electrolytes to Blood Pressure: A Study on Three Chinese Populations

Abstract: The relationship of diet to blood pressure was studied in a total of 705 men and women aged 40-59 from three Chinese population samples having different mean blood pressure and dietary sodium and animal protein intake. Two groups were farmers from Shanxi in northern China, and Guangxi in southern China, and the third were fishermen from Zhejiang, eastern China. Three 24-hour dietary recalls were done for each participant. Serum and overnight urine amino acids were measured in random subsamples. Determination of electrolytes in three 24-hour urine specimens was done in an additional sample of 59 men in each population. Results of multiple or stepwise regression showed: 1) in the pooled group, individual intake of sodium was positively associated with systolic blood pressure; 2) when stratifying by median calcium intake, a positive association of dietary sodium or sodium/potassium was found only in the group with calcium intake lower than the median; 3) daily intake of animal protein, urinary sulphate and certain serum and urine amino acids formed from protein metabolism, were inversely associated with blood pressure.

A Medical Perspective

Abstract: Over the past 3 years, a greater understanding of predisposing factors and the pathology of the aortic wail has yielded more insights into the pathogenesis, as well as into more accurate diagnostic and preventive methods. This update will discuss: (1) the incidence, definition, and recent classification of aortic dissection; (2) epidemiology, medical, and recent surgical series; (3) the pathogenesis and risk factors; (4) clinical features and evolving nonin-vasive imaging approaches to diagnosis; and (5) management from a medical perspective. (J Card Surg 1994;9:713–728)

A north-south comparison of blood pressure and factors related to blood pressure in the People's Republic of China: a report from the PRC-USA Collaborative Study of Cardiovascular Epidemiology.

Abstract: Objectives: To compare blood pressures in northern (Beijing) and southern (Guangzhou) Chinese population samples aged 35-54 years, males and females, urban and rural, and to assess the role of blood pressure-related traits in explaining north-south differences Design: Cross-sectional surveys were conducted in 1983-1984 of northern and southern populations employed in industry (urban) or farming (rural) Methods: In the north samples were selected from the Capital Iron and Steel Complex (urban) and Shijingshan district (rural); in the south samples from the Guangzhou Shipyard (urban) and Panyu County (rural) were used Results: The number of subjects surveyed in north and south were 4706 and 4179, respectively: 1500 and 1052 urban males, and 717 and 914 rural males; and 1300 and 1061 urban females, and 1189 and 1152 rural females, respectively

Endogenous adenosine does not activate ATP-sensitive potassium channels in the hypoxic guinea pig ventricle in vivo

Abstract: BACKGROUND The activation of ATP-sensitive K+ (K+ ATP) channels by K+ ATP openers, eg, pinacidil, hypoxia, and ischemia, is known to shorten the ventricular action potential. Since adenosine is released in increased amounts during cardiac hypoxia and ischemia, the hypothesis that endogenous adenosine activates K+ ATP channels was tested in vivo in a guinea pig model. METHODS AND RESULTS Anesthetized animals (n = 37) were subjected to transient acute global hypoxia by ventilation with 100% N2. Monophasic action potentials (MAP) were recorded in ventricular and atrial myocardium by use of custom-made Ag/AgCl electrode catheters. In addition, right atrial and left ventricular electrograms as well as systemic arterial blood pressure were monitored throughout the experiments. Under normoxic conditions, pinacidil (1.8 microgram/kg i.v., n = 8), a K+ ATP channel opener, shortened ventricular MAP duration (APD); this effect was reversed by glibenclamide, a potent K+ ATP channel blocker, but not by 8-cyclopentyl-1,3-dimethylxanthine (CPT), a potent A1-selective adenosine antagonist. Global hypoxia shortened atrial and ventricular APD. Glibenclamide but not CPT reversed this effect of hypoxia on ventricular but not atrial MAP. CPT but not glibenclamide reversed the effect of hypoxia on atrial MAP. In addition, CPT delayed the appearance of the atrioventricular (AV) nodal conduction block associated with global hypoxia. Finally, the ability of CPT to selectively attenuate A1-adenosine receptor-mediated effects of adenosine agonists in ventricular and supraventricular tissues was confirmed in 17 animals. CPT reversed the negative dromotropic effect of adenosine on AV nodal conduction and the antiadrenergic effect of N6-cyclopentyladenosine (CPA) mediated by A1-adenosine receptor but not the adenosine-induced decrease in systemic blood pressure caused by the vasodilatory action of the nucleoside mediated by A2-adenosine receptor. CONCLUSIONS (1) Endogenous adenosine released during global cardiac hypoxia mediates, in part, AV nodal conduction delay and shortening of atrial but not ventricular APD. (2) The action of adenosine on atrial APD is mediated by A1 adenosine receptors, probably via IK,Ado,Ach. (3) Endogenous adenosine apparently does not play an important role in the early stages of acute global hypoxia-induced activation of K+ ATP channels. The present results are consistent with the hypothesis that the shortening of ventricular APD in the hypoxic heart is due, in part, to activation of K+ ATP channels.

Niacin-Induced Myopathy

Abstract: Treating hypercholesterolemia is effective both for the prevention and regression of coronary artery disease. 1–3 Lipid-lowering agents are being used more frequently and practitioners are therefore more likely to encounter the unusual side effects of these drugs. Niacin (nicotinic acid, vitamin B3) inhibits very-low-density lipoprotein secretion by the liver. It lowers total cholesterol, low-density lipoprotein (LDL) and triglycerides and raises high-density lipoprotein (HDL). Treatment with niacin may reduce the incidence of nonfatal myocardial infarctions, and in conjunction with bile resins, promote regression of coronary lesions.1–3 It is the only lipid-lowering agent shown to reduce mortality,3 and has been given at lower doses to treat hypoalphalipoproteinemia (selective low levels of HDL). Niacin in conjunction with 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors increases the risk of myopathy associated with the latter.2 We report here 2 cases of myopathy induced by niacin without concomitant treatment with other hypolipidemic agents and review the relevant literature.

Pulmonary artery involvement in aortoarteritis: an angiographic study.

Abstract: Angiographic findings of 47 patients with pulmonary artery involvement (PAI) in aortoarteritis are described together with the diagnostic evaluation of PAI and its clinical implications. Pulmonary arteriography was obtained by intravenous digital subtraction angiography in 133 patients with aortoarteritis; 45 (33.8%) were found to have PAI. Two patients with PAI, studied by conventional arteriography, are also included. Stenosis and/or occlusion of segmental and/or lobar pulmonary arteries, and subsegmental branches, were the basic angiographic findings in PAI. Pulmonary artery branches in the upper lobes were more commonly affected than those in the lower and middle (lingula) lobes. Bilateral lesions were more common than unilateral ones. Single lobar and segmental lesions were quite rare. Dilatation was uncommon. No main pulmonary artery involvement was detected. Pulmonary artery hypertension, a late complication of patients with PAI, was revealed in 9 of the 46 patients of the present series. If it occurs, PAI becomes a factor effecting the patient's clinical course and prognosis.

Management of the coronary-subclavian steal syndrome with balloon angioplasty. A case report and review of the literature.

Abstract: A fifty-two-year-old woman with angina pectoris due to coronary-subclavian steal syndrome through a left internal mammary artery graft placed distal to a left anterior descending artery stenosis is presented. Retrograde flow through the mammary artery graft due to severe left subclavian stenosis was observed angiographically. Accordingly, left subclavian balloon angioplasty was performed, restoring normal antegrade flow through the internal mammary artery graft and resulting in resolution of the patient's symptoms. The patient was subsequently discharged with no evidence of angina. Carotid-subclavian bypass surgery was avoided, reducing patient discomfort, procedural risk, and expense.

“Late” proarrhythmia due to quinidine

Abstract: Late proarrhythmia due to quinidine is obviously not forewarned by the occurrence of early torsades de pointes, and initial in-hospital use and monitoring may not necessarily ensure or predict long-term safety. It is possible that late torsades de pointes, as profiled in this report, explains the increased mortality in patients receiving chronic quinidine therapy observed in previous investigations.

Electrophysiological-anatomic correlates of ATP-triggered vagal reflex in dogs. II. Vagal afferent traffic.

Abstract: Extracellular ATP can act on chemosensitive vagal C-fiber nerve terminals in the lungs, thereby eliciting a pulmonary-cardiac depressor reflex. Previous studies have shown a right vagal dominance in afferent traffic elicited by intra-right atrial ATP. To elucidate the mechanism of this phenomenon, the following hypotheses were tested in a canine model. 1) Intra-right and intra-left pulmonary ATP elicit neural afferent traffic, which travels via the right and left vagus nerves, respectively. 2) Intra-right vs. intra-left pulmonary ATP causes similar suppression of sinus node automaticity. Data obtained in this study support both hypotheses and suggest that right vagal dominance in afferent neural traffic elicited by ATP is probably due to the action of ATP and/or its metabolites on nonpulmonary tissues.

A case of Bacillus cereus prosthetic valve endocarditis

Abstract: A rare case of prosthetic valve endocarditis by Bacillus cereus was reported. The patient was 43-year-old Japanese man, who had mitral valve replacement 5 months prior to this admission. Remitral valve replacement was immediately done successfully. His postoperative course was uneventful for 8 months.

Drugs for treatment of patients with high cholesterol blood levels and other dyslipidemias

Abstract: Atherosclerotic coronary artery disease (ASCAD) is the most common cause of morbidity and mortality in most developed nations. Dyslipidemia increases the risk of ASCAD. Diet, lifestyle habits, and/or lipid-acting drugs that favorably affect lipid blood levels have been shown to decrease progression, or in some cases induce regression of ASCAD. Therefore, lipid-acting drugs have been recommended for dyslipidemic patients with ASCAD, or at high risk for ASCAD, who do not correct their lipid blood levels after diet and lifestyle recommendations. The choice of the type of lipid-acting drug/s should be based on the blood lipid profile, as well as the potential effectiveness, tolerance, and toxicity anticipated in the individual patient.

Superficial Femoral Vein Valve Repair with Limited Anterior Plication

Abstract: Objective: To evaluate the effects after 3 years of a new surgical technique, limited anterior plication (LAP) of the superficial femoral vein. Design: Patients with venous hypertension resulting from deep and superficial venous incompetence were randomized into two treatment groups. Setting: Angiology and Vascular Surgery, Pierangeli Clinic, Pescara, and Cardiovascular Institute, Chieti University, Italy. Patients: Both groups were treated with superficial vein surgery. Group 2 was also treated with LAP. Interventions: Valvuloplasty of the superficial femoral vein was performed with plication of the anterior vein wall after limited dissection of the vein. Main outcome measures: During a 3-year follow-up results were evaluated with colour duplex and ambulatory venous pressure (AVP) measurements. Endpoints were AVP, refilling time (RT), number of incompetent venous sites, presence/absence of the reflux at the superficial femoral vein and the diameter of the vein. Results: No complications were observed. All femoral veins treated with LAP were competent at 36 months. Significantly lower AVP and longer RT were observed in the LAP group. The number of incompetent venous sites was lower in both groups. The average diameter of the vein was higher in Group 1. Conclusions: In selected subjects – moderate deep venous incompetence, functional cusps, incompetence mainly due to relative enlargement of the vein – LAP may be an alternative to external valvuloplasty.

Wave transmission and input impedance of a model of skeletal muscle microvasculature.

Abstract: We analyzed wave transmission properties and input impedance of a microvascular network model. The model, derived from rat spinotrapezius muscle and previously described and validated by other investigators for steady pressure-flow relations, was expanded to include pulsatile phenomena. Microvessels are considered purely elastic, with compliances a function of vessel type; viscous dissipation follows Poiseuille's law. Linear and nonlinear results are presented. In the nonlinear case, shear rate-dependent viscosity of blood and transmural pressure-dependent vascular diameters were calculated and small signal perturbations were imposed around several working points. We investigated effects on input impedance of physiological variability of network parameters and structure: distribution of capillary diameters, capillary segment length, and presence or absence of cross-connecting capillaries. Results show that although wave transmission properties are complex, input impedance is simple. Apparent wave speeds differ substantially from phase velocities and change markedly from branch to branch; pressure and flow waves appear to travel at different speeds. These features result from the mesh-like structure of the network and the prominence of reflection at branchpoints. Input impedance displays a similar form under all conditions: Magnitude is a monotonically decreasing function of frequency, and phase decreases from 0 to approximately −45°. Consideration of the characteristic impedance of a microvessel leads to modification of the three-element Windkessel as a reduced model of the observed input impedance.

Subclinical arteriosclerosis screening. The PAP/PEA study. Prevalenza dell'Arteriosclerosi Precoce (Prevalence of Early Arteriosclerosis).

Abstract: Noninvasive screening of subclinical atherosclerosis is possible with ultrasonic biopsy (UB) performed with high resolution ultrasound scanning. Five UB classes have been identified, each class corresponding to a different incidence of cardiovascular events (CVE) in 4 years and silent coronary ischemia (SCI). In a study including 2230 asymptomatic subjects 3 risk groups were defined. In the low risk group (class I and II; 82.01% of the population sample) the incidence of CVE and SCI was zero. These subjects may be seen again after 3 years. In the moderate risk group (class II and IV; 13.3%) monitoring and early intervention may be needed. In the high risk group (class V; 4.6%) prophylaxis or treatment may be necessary. The screening is effective, simple and may be organised at very low cost--i.e. 30.000 asymptomatic subjects may be scanned at the cost of 100.000 ECU. Each scan, including carotid and femoral bifurcations, may be performed in 15 minutes. In our communities this cost is equivalent to the average cost of a single major stroke or major coronary ischemic event in a working adult aging between 45 and 60. Organization problems and the fragmentation of competences has prevented the evolution of atherosclerosis screening. The problem can be solved organising a network including epidemiologists, angiologists and cardiovascular surgical centres where all phases of atherosclerosis may be studied and detected, progression prevented and complications treated with a global vision of the disease.

Radiation-Induced Cardiovascular Disease Including Stenosis of Coronary Ostium, Coronary and Carotid Arteries, and Aortic Valve

Abstract: Clinical and necropsy findings are described in a 42-year-old man who received mediastinal irradiation (about 40 Gy) for Hodgkin's disease when he was 24 years old. He subsequently developed virtually every cardiovascular manifestation of radiation heart disease, including constrictive pericardial disease, complete occlusion of the ostium of a coronary artery, severe narrowing of the right coronary artery and of both carotid arteries, complete heart block (infranodal), hemodynamically confirmed aortic valve stenosis, and transmural right ventricular infarction.

The influence of age and location of arterial lesion on the pathogenesis and development of early atherosclerotic lesions in youth.

Abstract: From 1986 to 1989, 324 aortae from accidental death aged 15-39 were collected from two locations, one of higher prevalence (Beijing in North China), and the other of lower prevalence (Nanning in South China) of atherosclerosis (AS) and coronary heart disease (CHD). Morphometry and biochemical analyses, were used in the study with emphasis on the changes of smooth muscle cells (SMC) in the aortic intima and on the aortic proteoglycans (PGs) of specimens from both locations to elucidate their relationship with the pathogenesis and development of AS and to find ways, if any, for the prevention and control of AS. The results showed that the densities, especially the area density of the cell nuclei of aortic SMC were significantly higher in specimens from the North than those from the South (P < 0.01). Nuclear densities of SMC negatively correlated with alcian blue-positive substances; both total PGs and Heparin sulfate PG (HSPG, inhibitory to SMC proliferation) of the aortic intima and media were lower in specimens from the North than those from the South (P < 0.01). The percentage of sudanophilic lesion (SL) in the total intimal area, showing the extent of fatty infiltration of aortae from the two locations, was similar except that of the male abdominal aortae which was higher in the North (P < 0.01). The above findings showed that decreased content of HSPG which is inhibitory to SMC proliferation might be one of the causes of the augmentation of aortic SMC proliferation in Beijing specimens; and also the increased serum cholesterol concentration of the population in Nanning was reflected in the SL of the aortic intima.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship between dietary factors and serum lipids in southern Chinese population samples.

Abstract: As part of the PRC-USA collaborative research project on the epidemiology of cardiovascular disease, baseline surveys were conducted in four random urban and rural samples in Guangzhou, Guangdong Province in southern China on 334 men and women aged 35-54 in the fall of 1983-84 with the aim of studying the correlation between dietary intakes and serum lipids. Methods standardized by the US Centers for Disease Control were used for measuring different parameters, and quality control was emphasized to assure comparability between workers and farmers. Three 24-hour recalls were collected from each participant in each survey. Mean values of daily intakes of nutrients per capita for the four groups were as follows: 59-69% kcal carbohydrate; 10-12% kcal protein; 22-26% kcal fat. Dietary total fat, saturated fatty acid (SFA), polyunsaturated fatty acid (PUFA) and cholesterol were higher in the urban than the rural areas. Mean levels of serum total cholesterol (TC), triglycerides (TG), high density lipoprotein cholesterol (HDL-C) and low density lipoprotein cholesterol (LDL-C) were 4.6 mmol/l, 1.1 mmol/l, 1.3 mmol/l and 2.8 mmol/l respectively. The TC, TG and LDL-C and HDL-C were significantly higher in the urban than the rural areas. Analyses of correlation showed that the Keys 'dietary lipid score' was positively associated with TC, LDL-C and HDL-C; specifically, dietary cholesterol was positively associated with serum TC. Saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) were positively correlated with HDL-C. It seems that the traditional dietary pattern of Guangzhou favours serum lipids being at an optimal level.

[A case report of thymolipoma with high titer of serum anti-acetylcholine receptor antibodies--thymolipoma, a review of 49 reports in Japan].

Abstract: A 22-year-old man was diagnosed as thymolipoma by chest CT scan & MRI. In spite of high titer of serum anti-acetylcholine receptor antibodies, he showed no symptom of myasthenia gravis. An extended thymectomy was done successfully. Tumor was 21 x 15 cm in size and 620 g in weight. Histopathologically the tumor was diagnosed as thymolipoma. The titer of serum anti-acetylcholine receptor antibodies was decreased within normal limit and postoperative course was uneventful. To our knowledge, the 49 case reports in Japan were reviewed.

Relation between weight and body fat's distribution and ambulatory blood pressure in chinese elderly

Abstract: Ninety-five subjects aged 60 years and over underwent casual and ambulatory blood pressure (BP) measurements as well as weight, height, both waist and hip circumferences and both upper arm and thigh circumferences. Most anthropometric variables were significantly correlated with measures of BP. One stepwise regression analysis was applied to reveal that among measures of BP, 24-hour systolic BP had the strongest correlation with waist/hip ratio and awaking diastolic BP the strongest correlation with weight, both waist and hip circumferences and body mass index. Another was used to show that waist/hip ratio was the best overall predictor of systolic BP and weight the best overall predictor of diastolic BP. We suggest

Upper rate lockout: an unexpected feature of rate adaptive atrioventricular delay.

Abstract: We present a case in which use of rate adaptive AV delay resalted in unexpected pacemaker 2:1 AV block when the patient's atrial rate exceeded the pacemaker maximum tracking rate but was below the predicted multiblock rate. “Lockout” of normal upper rate behavior was accompanied with the requirement of a slower atrial rate for reassociation than loss of atrial tracking, a form of upper rate hysteresis. The mechanism of upper rate lockout is discussed, along with potential ways to avoid the problem. The use of software based pacemakers with an extended range of programmable options allows the most flexibility in optimizing pacemaker performance in an individual patient.