Accelerated intimal thickening in carotid arteries of balloon-injured rats after immunization against heat shock protein 70.

OBJECTIVES: The goal of this study was to test the hypothesis that induction of an immune response to heat shock protein (Hsp) 70 would increase intimal thickening in a rat carotid-injury model. BACKGROUND: Restenosis resulting from intimal thickening poses a major limitation to the long-term success of coronary angioplasty. Several studies have proposed that infectious agents increase restenosis. Heat shock proteins are highly conserved structures, produced by all cells in response to nonspecific forms of stress. Infectious agents are known to contain Hsp70, which is markedly immunogenic and can elicit a strong immune response. METHODS: To investigate whether Hsp70 immunity can affect neointimal thickening, we immunized rats with either Hsp70 (n = 11), bovine serum albumin ([BSA] n = 9) or with a control adjuvant (n = 10). Three weeks later, rats were boosted using the same regimen to achieve a sustained immune response to Hsp70 after which carotid injury was applied to all animals. RESULTS: Arterial injury was associated with upregulation of Hsp70, 3, 7 and 14 days after induction of the injury as evidenced by Western blotting and immunohistochemistry. Intimal area and intimal/medial ratio was significantly increased in Hsp70-immunized rats in comparison with BSA or control-injected rats. CONCLUSIONS: Our results imply that upregulation of Hsp70 in balloon-injured arteries can serve as a target for anti-Hsp70 immune response, thereby facilitating enhanced intimal thickening. These observations may provide a possible mechanism that explains the accelerated intimal thickening that has been associated with the occurrence of infectious pathogens.

The "SHAHAL" experience in Israel for improving diagnosis of acute coronary syndromes in the prehospital setting.

The diagnosis of acute coronary syndromes is frequently missed, and many high-risk patients fail to be admitted to hospital. The aim of this study was to assess the value of cardiac markers in ruling out acute ischemic events in patients with symptoms of possible cardiac origin and nondiagnostic electrocardiograms. The data collected between May 1999 and April 2000 for this prospective cohort study were retrieved from the records of 777 consecutive prehospital patients (mean age 70 years, 62.9% men) whose symptoms lasted for 6 to 48 hours, who were treated by mobile intensive care teams, and for whom the physician could not reach a clear-cut decision whether they should be taken to hospital or left at home. The cardiac markers, creatine kinase (CK-MB), myoglobin, and troponin I, were measured at the scene using a rapid Stat kit to qualitatively detect their presence in whole blood samples. Results were determined after 15 minutes at the scene. The assay was positive in 30 patients, 11 of whom had a definite cardiac diagnosis (acute myocardial infarction in 4 and unstable angina pectoris in 7). Positive and negative predictive values of the assay for detecting a significant coronary event were 36.7% and 100%, respectively. Of the 747 patients with a negative result, 6 patients had a false result (1 with myocardial infarction and in 5 with unstable angina) (99.2% negative predictive value). Thus, cardiac markers are useful in ruling out high-risk coronary syndromes in the prehospital setting when the clinical presentation and electrocardiogram are inconclusive.

The effect of intravenous immunoglobulins on the progression of experimental autoimmune myocarditis in the rat.

The aim of this study was to evaluate the efficacy of two experimental regimes of human intravenous immunoglobulins (IVIG) on the progression of experimental autoimmune myocarditis (EAM). EAM is induced by immunization against myosin and represents a T-cell-dependent disorder that progresses toward dilated cardiomyopathy similar to the human equivalent. No effective treatment is currently at hand for management of the disorder, as immunosuppressant drugs are associated with multiple side effects. Three groups of Lewis rats were induced to develop EAM by immunization with porcine myosin and sacrificed 21 days later. Group A received a 5-day regimen of IVIG (800 mg/kg) following induction of the disorder; Group B received a daily dose of IVIG (800 mg/kg) and group C was treated with PBS. IVIG given daily but not during the first 5 days significantly suppressed myocarditis score (0.81 +/- 0.26 and 1.14 +/- 0.42, respectively) in comparison with controls (mean score of 1.78 +/- 0.36). The effect was accompanied by a reduction in the cellular and humoral immune response of the respective animals toward myosin. IVIG was deposited within the extracellular matrix surrounding the damaged myocytes. TNF-alpha expression was reduced in both groups treated with IVIG, whereas iNOS expression paralleled the extent of myocardial inflammation regardless of treatment. IVIG at doses twice those applied for human disease are effective in ameliorating the progression of EAM. The effect may be mediated by suppression of the cellular and humoral response to myosin. IVIG may be found clinically feasible in humans as an adjuvant or single therapy for autoimmune myocarditis.

The effect of agmatine administration on ischemic-reperfused isolated rat heart.

BACKGROUND: The natural polyamine Agmatine (Ag) plays a significant role in protection of nerve cell ischemic injury. A previous report indicated that Ag given intraperitoneally to rats enhanced the recovery of the heart from ischemic injury. Based on this initial observation, a larger investigation was undertaken to explore a dose-response effect and possible mechanisms underlying the protective effects. METHODS: Using the modified Langendorff model, 36 isolated hearts were divided into five groups: group 1, hearts receiving 100 microM/L Ag pre-ischemia (n=7); group 2, hearts receiving 100 microM/L Ag pre- and post-ischemia, (n=7); group 3, hearts receiving 250 microM/L Ag pre-ischemia (n=7); group 4, hearts receiving 250 microM/L Ag pre- and postischemia (n=7); and group 5, hearts receiving Krebs-Hensleit solution served as control (n=8). The study design included 20 minutes of perfusion, 30 minutes of global ischemia, and 30 minutes of reperfusion. RESULTS: After ischemia, group 2 developed higher left ventricular pressure P(max) (P<0.01), improved first-derivative of the rise (dP/dt max; P<0.02), and fall (dP/dt min; P<0.04) in left ventricular pressure, and the area calculated under the left-ventricle developed pressure curve (pressure-time integral; P<0.015), but coronary flow was not significantly increased (P=0.06) compared to the control group. Group 1 had improved diastolic recovery: dP/dt min (P<0.05) and coronary flow (P<0.03), compared with the control group. Group 3 had improved P(max) (P<0.01), dP/dt min (P<0.01), and coronary flow (P<0.02); group 4 had no improvement in all hemodynamic parameters. CONCLUSION: Low doses of Ag given pre- and post-ischemia, and high doses given only pre-ischemia have favorable, protective effects on the hemodynamic recovery of isolated rat heart undergoing global ischemia and reperfusion.

The effect of correction of mild anemia in severe, resistant congestive heart failure using subcutaneous erythropoietin and intravenous iron: a randomized controlled study.

OBJECTIVES: This is a randomized controlled study of anemic patients with severe congestive heart failure (CHF) to assess the effect of correction of the anemia on cardiac and renal function and hospitalization. BACKGROUND: Although mild anemia occurs frequently in patients with CHF, there is very little information about the effect of correcting it with erythropoietin (EPO) and intravenous iron. METHODS: Thirty-two patients with moderate to severe CHF (New York Heart Association [NYHA] class III to IV) who had a left ventricular ejection fraction (LVEF) of < or =40% despite maximally tolerated doses of CHF medications and whose hemoglobin (Hb) levels were persistently between 10.0 and 11.5 g% were randomized into two groups. Group A (16 patients) received subcutaneous EPO and IV iron to increase the level of Hb to at least 12.5 g%. In Group B (16 patients) the anemia was not treated. The doses of all the CHF medications were maintained at the maximally tolerated levels except for oral and intravenous (IV) furosemide, whose doses were increased or decreased according to the clinical need. RESULTS: Over a mean of 8.2+/-2.6 months, four patients in Group B and none in Group A died of CHF-related illnesses. The mean NYHA class improved by 42.1% in A and worsened by 11.4% in B. The LVEF increased by 5.5% in A and decreased by 5.4% in B. The serum creatinine did not change in A and increased by 28.6% in B. The need for oral and IV furosemide decreased by 51.3% and 91.3% respectively in A and increased by 28.5% and 28.0% respectively in B. The number of days spent in hospital compared with the same period of time before entering the study decreased by 79.0% in A and increased by 57.6% in B. CONCLUSIONS: When anemia in CHF is treated with EPO and IV iron, a marked improvement in cardiac and patient function is seen, associated with less hospitalization and renal impairment and less need for diuretics.

The use of subcutaneous erythropoietin and intravenous iron for the treatment of the anemia of severe, resistant congestive heart failure improves cardiac and renal function and functional cardiac class, and markedly reduces hospitalizations.

OBJECTIVES: This study evaluated the prevalence and severity of anemia in patients with congestive heart failure (CHF) and the effect of its correction on cardiac and renal function and hospitalization. BACKGROUND: The prevalence and significance of mild anemia in patients with CHF is uncertain, and the role of erythropoietin with intravenous iron supplementation in treating this anemia is unknown. METHODS: In a retrospective study, the records of the 142 patients in our CHF clinic were reviewed to find the prevalence and severity of anemia (hemoglobin [Hb] <12 g). In an intervention study, 26 of these patients, despite maximally tolerated therapy of CHF for at least six months, still had had severe CHF and were also anemic. They were treated with subcutaneous erythropoietin and intravenous iron sufficient to increase the Hb to 12 g%. The doses of the CHF medications, except for diuretics, were not changed during the intervention period. RESULTS: The prevalence of anemia in the 142 patients increased with the severity of CHF, reaching 79.1% in those with New York Heart Association class IV. In the intervention study, the anemia of the 26 patients was treated for a mean of 7.2 +/- 5.5 months. The mean Hb level and mean left ventricular ejection fraction increased significantly. The mean number of hospitalizations fell by 91.9% compared with a similar period before the study. The New York Heart Association class fell significantly, as did the doses of oral and intravenous furosemide. The rate of fall of the glomerular filtration rate slowed with the treatment. CONCLUSIONS: Anemia is very common in CHF and its successful treatment is associated with a significant improvement in cardiac function, functional class, renal function and in a marked fall in the need for diuretics and hospitalization.

Arrhythmias in the congenital long QT syndrome: how often is torsade de pointes pause dependent?

OBJECTIVE: To determine the frequency and predictors of pause dependent torsade de pointes among patients with the congenital long QT syndrome and spontaneous ventricular tachyarrhythmias. DESIGN: The literature on the "congenital long QT" was reviewed. Articles with illustrations demonstrating the onset of spontaneous polymorphic ventricular arrhythmias in the absence of arrhythmogenic drugs were included. RESULTS: Illustrations of 62 spontaneous episodes of torsade de pointes among patients with congenital long QT syndrome were found in the literature. The majority (74%) of documented arrhythmias were "pause dependent"; 82% of these pauses were longer than the basic cycle length by > 100 ms. Age and sex correlated with the mode of arrhythmia initiation. Arrhythmias in infants (

Potential reduction of costs and hospital emergency department visits resulting from prehospital transtelephonic triage--the Shahal experience in Israel.

BACKGROUND: The rising cost of services provided by hospital emergency departments is of major concern. Attempts to reduce the costs of emergency cardiac care have thus far focused primarily on medical and administrative management in the hospital. The role of the patient in appropriate prehospital decision-making has been generally ignored. HYPOTHESIS: Membership in "Shahal" (an integrative telemedicine system) may have beneficial effects on patient decision-making and national health costs. METHODS: During a 6-month period, a random group of subscribers who had called for medical assistance during the previous 24 h were asked what action they would have taken had they not been Shahal subscribers. All study patients were followed for at least 7 days. RESULTS: In all, 1,608 subscribers (age 71 +/- 13 years) were included. Of these, 514 replied that they "would have waited," 363 "would have contacted their physicians," and 731 "would have sought emergency department care." Of the presenting medical problems, 86% were resolved without utilizing hospital facilities. A mobile intensive care unit was dispatched in 412 (26%) cases. A cost estimate of abuse indicated that the service resulted in a savings to the national economy of approximately $830,000 per 10,000 members per year. CONCLUSIONS: This study demonstrated that Shahal membership can reduce costs of medical care and the number of hospital emergency department visits.

Medical history of hypercholesterolaemia adversely affects the outcome of out-of-hospital cardiopulmonary resuscitation; the 'Shahal' experience in Israel.

AIMS: To evaluate the impact selected risk factors for cardiac death may have on the success rate in a large cohort of subscribers to 'SHAHAL' who were resuscitated from out-of-hospital cardiac arrest. METHODS AND RESULTS: In this medical facility currently serving 50 000 subscribers, data were prospectively gathered from between 1987-1998. The information retrieved from the patients' medical records included a medical history of hypertension, diabetes, hypercholesterolaemia (>220.mg. dl(-1)) smoking, angina, previous myocardial infarction, and congestive heart failure. A total of 998 patients aged 74+/-12 years (mean+/-1 SD) were included. Death was announced at the scene for 659 (66%) victims, while 339 (34%) patients were taken to hospital. Of these 140 (14% of the total cohort) survived and were discharged from the hospital. A comparison of various selected parameters between survivors and non-survivors of resuscitation revealed that survivors were younger, had a higher rate of pulseless ventricular tachycardia/ventricular fibrillation, more were among the arrests witnessed by the 'SHAHAL' team, and that more had a shorter time lag to initiation of cardiopulmonary resuscitation than non-survivors. None of the studied risk factors predicted the outcome of cardiopulmonary resuscitation, with the exception of hypercholesterolaemia, which carried a significantly worse prognosis for cardiopulmonary resuscitation (P=0.009). CONCLUSIONS: A medical history of hypercholesterolaemia appears to be an important risk factor which adversely affects the outcome of cardiopulmonary resuscitation.

Direct ultrasound application had no effect on cardiac hemodynamic performance in a baseline isolated rat heart model.

Therapeutic ultrasound (US) has been used for more than 3 decades to promote tissue healing in cases of tissue injury and muscle soreness. It was previously suggested that US may have vasorelaxatory and inotropic properties. However, the direct effect of therapeutic US in a whole heart model has not yet been investigated. Our hypothesis was that application of US might enhance cardiac function. The Langendorf model was modified in a special manner to allow application of US to the heart. Using this model, 20 male rats were equally divided into two groups. Group 1: the hearts were perfused for 15 min, to obtain baseline measurements, and then they were perfused for another 15 min in a special bath full of perfusate. Group 2: after 15 min of baseline measurements, continuous US of 1 MHz 2 W/cm(2) was applied for another 15 min. The parameters that were measured at 5-min intervals were: left ventricular pressure P(max), first derivative of the rise and fall in left ventricular pressure (dP/dt(max), dP/dt(min)), and pressure-time integral. There was no significant difference between the two groups in all parameters at baseline and during US application. P(max) and dP/dt(max) remained constant. After 15 min of US propagation, P(max) was 98% +/- 3 from baseline level vs. 98% +/- 7 in the control group, and dP/dt(max) was 98% +/- 3 vs. 99% +/- 9 in the control. In dP/dt(min), a gradual decline after 15 min of perfusion was measured. In the US- treated group, it declined to 80% +/- 10 vs. 83% +/- 5 in the controls. In conclusion, US radiation at the dose specified does not improve healthy isolated heart hemodynamic performance. We established a model that may be used for further investigation.

Captopril and L-arginine have a synergistic cardioprotective effect in ischemic-reperfusion injury in the isolated rat heart.

OBJECTIVES: The present study was designed to evaluate the possible effect of the combined administration of both captopril (Cap) and L-arginine (L-a) in the isolated ischemic rat heart model. BACKGROUND: Recent studies suggest that L-arginine and angiotensin-converting enzyme (ACE) inhibitors possess independent cardioprotective effects in ischemic hearts. The pharmacological effect of the combination of both drugs has not yet been investigated in the ischemic myocardium. METHODS: Using the modified Langendorf model, rats were perfused with either Cap 360 micromol/L (n = 6) or (L-a) 3mmol/L (n = 6), both captopril and L-arginine (Cap+L-a) (n = 8), or saline control (Con) (n = 8). The study design included 30 minutes of perfusion, 30 minutes of global ischemia, and 30 minutes of reperfusion thereafter. RESULTS: Hearts treated with both Cap+L-a demonstrated an improved performance in all parameters. After 10 minutes of reperfusion, the P(max) in the Cap+L-a group was 98 +/- 8 mmHg (P <.001), 59 +/- 14 mmHg in the Cap group (P <.02), and 44.3 +/- 10 mmHg in the L-a group (P = NS), compared with only 42 +/- 8 mmHg in the control. After 10 minutes of reperfusion the dP/dt(min) was: in the Cap+L-a group: -1,650 +/- 223 mmHg/s (P <. 006); in the Cap group: -1,051 +/- 302 mmHg/s (P <.03); in the L-a group: -870 +/- 131 mmHg/s (P = NS), compared with only -487 +/- 131 mmHg/s in the control. Coronary flow was significantly increased in all 3 groups: Cap+L-a group: 22.3 +/- 1.5 mL/min (P <.001); Cap group: 18 +/- 1.6 mL/min (P <.01); L-a group: 19.8 +/- 0.9 mL/min (P <.02), compared with 12.6 +/- 0.9 mL/min in the Con group. Total NO level was significantly increased in the Cap+L-a group: 13.4 +/- 2 micromol (P <.03) vs. 6.1 +/- 1 micromol for the L-a group. NO levels of both the Cap group and the Con group were beneath detectable values. CONCLUSION: Combined administration of captopril and L-arginine has a synergistic, protective effect on heart function and coronary flow that may be mediated by enhanced NO production.

Circadian variation of symptomatic paroxysmal atrial fibrillation. Data from almost 10 000 episodes.

AIMS: To determine the circadian rhythm of paroxysmal atrial fibrillation in a very large outpatient population. METHODS AND RESULTS: We reviewed all emergency telephone calls received in Shahal (a medical service covering 44 000 subscribers), from 1987 to 1997. Patients were included if new-onset atrial fibrillation was recorded. During this study period, 9989 episodes of paroxysmal atrial fibrillation were recorded. The time of onset was not uniformly distributed throughout the 24 h period. Instead, the distribution of arrhythmic episodes showed a double peak, with a significant increase in the number of episodes in the morning and a second rise in the evening (P<0.001). A non-uniform weekly distribution of events was also noted, with substantially fewer episodes on Saturdays (P<0.001). Finally, more arrhythmias occurred during the last months of each year (P<0.001). CONCLUSIONS: The onset of paroxysmal atrial fibrillation does not occur randomly. The large patient population in the present study suggests that the circadian rhythm of paroxysmal atrial fibrillation is similar to that described for other cardiovascular diseases, with clustering of events in the morning and (to a lesser degree) late in the evening. Weekly and yearly circadian patterns are also prominent.

Assessment of a creatine kinase-MB/myoglobin kit in the prehospital setting in patients presenting with acute nontraumatic chest pain: the "Shahal" experience.

OBJECTIVES: To evaluate the usefulness of a novel qualitative, rapid, bedside immunoassay device for the detection of elevated creatine kinase MBmass (CK-MB) and myoglobin as a supportive tool for decision-making by the physician who is evaluating patients who present with chest pain. DESIGN: Prospective study. SETTING: Prehospital (mobile intensive care units). PATIENTS: Three hundred twenty-eight consecutive patients, age 71+/-13 yrs (64% males), who were admitted to the hospital via Shahal's mobile intensive care units. INTERVENTION: During a 6-month period, based on clinical presentations and electrocardiograms, the mobile's physicians classified patients into groups of high or low probability of having an acute myocardial infarction and, thereafter, used a rapid bedside STATus kit (Spectral Diagnostics, Toronto, Ontario, Canada) to determine blood creatine kinase/MB and myoglobin. MEASUREMENTS AND MAIN RESULTS: Myocardial infarction was confirmed in 59 (18%) patients. If measured >2 hrs after onset, diagnostic sensitivities, specificities, and positive and negative predictive values for physicians were as follows: 71%, 90%, 46%, and 96%, respectively, compared with 100%, 85%, 44%, and 100%, respectively, if assessed by the kit. CONCLUSIONS: If used 2 to 12 hrs from the onset of symptoms, this device is a convenient diagnostic aid to prevent a misdiagnosis of acute myocardial infarction or unnecessary hospitalization to exclude infarction. This tool may be a promising cost-cutting factor in these days of escalating expenses and dwindling resources.

Clinical and inflammatory effects of dietary L-arginine in patients with intractable angina pectoris.

We evaluated the effects of oral L-arginine on the clinical outcome and the inflammatory markers of patients with intractable angina pectoris. Our findings demonstrated a significant clinical improvement in 7 of 10 patients, which was associated with a significant decrease in cell adhesion molecule and proinflammatory cytokine levels. Dietary L-arginine may have clinical beneficial effects in patients with intractable angina pectoris, and may have anti-inflammatory properties.

Circadian rhythm of acute pulmonary edema.

We found that the onset of acute pulmonary edema demonstrates circadian periodicity. Most episodes occur in the morning or at night. Pulmonary edema occurs more frequently during the colder months.

The "telepress" system for self-measurement and monitoring of blood pressure (the "SHAHAL" experience in Israel).

No "white coat" effect contaminated the validity of measurements in 30 participants in a "Telepress" program, in which subscribers to a telecardiologic facility transtelephonically transmit their self-measured blood pressure values.

Percutaneous transluminal therapy of occluded saphenous vein grafts: can the challenge be met with ultrasound thrombolysis?

BACKGROUND: Percutaneous transluminal treatment of a thrombotic vein graft yields poor results. We have previously reported our experience with transluminal percutaneous coronary ultrasound thrombolysis (CUT) in the setting of acute myocardial infarction (AMI). This report describes the first experience with ultrasound thrombolysis in thrombus-rich lesions in saphenous vein grafts (SVGs), most of which were occluded. METHODS AND RESULTS: The patients (n=20) were mostly male (85%), aged 64+/-4 years old. The presenting symptom was AMI in 2 patients (10%) and unstable angina in the rest. Fifteen patients (75%) had totally occluded SVGs. The median age of clots was 6 days (range, 0 to 100 days). The ultrasound thrombolysis device has a 1.6-mm-long tip and fits into a 7F guiding catheter over a 0.014-in guidewire in a "rapid-exchange" system. CUT (41 kHz, 18 W,

The Effect of Agmatine on Ischemic and Nonischemic Isolated Rat Heart.

OBJECTIVE: the natural polyamines play a protective role during ischemic injury. We studied the effects of agmatine on ischemic and nonischemic isolated rat hearts. METHODS: Thirty-one rats were randomly assigned to one of four experimental groups. Sixteen rats were injected with saline (group 1, n = 9; group 3, n = 7), and 15 rats were injected with 100 mg/kg of agmatine (group 2, n = 8; group 4, n = 7). Injections were given twice: 24 hours and 1 hour before the experiment. Using the modified Langendorf model, rat hearts were perfused with Krebs-Henseleit solution for 105 minutes during phase 1 of the experiment (groups 1 and 2). During phase 2, hearts were exposed to 45 minutes of global ischemia (groups 3 and 4). RESULTS: During phase 1, no statistically significant differences were observed between the agmatine and the control groups. During phase 2, agmatine caused a significant increase in left ventricular pressure (P <.003). At the end of reperfusion, P(max) was 111% +/- 10% from the baseline levels versus only 82% +/- 5% in the control group. After 20 minutes of reperfusion, dP/dt (first-time derivative of the ventricular pressure) in the agmatine group reached full recovery of 106% +/- 12% versus only 64% +/- 14% in the saline group (P =.059). Agmatine also caused a significant increase in coronary flow rate (P <.004) throughout the reperfusion period. Quantitative immunohistochemical staining disclosed reduced cell damage in the agmatine-treated hearts (P <.02) versus the control group. CONCLUSION: Agmatine injection given before induced ischemia improves hemodynamic recovery by mechanisms that may be attributed to its vasodilatory properties.

Fractal organization of the pointwise correlation dimension of the heart rate.

OBJECTIVE: To depict and quantify the degree of organization of the heart rate variability (HRV) in normal subjects. METHODS: A modified algorithm was created to estimate series of 'point-dimensions' (PD2) from interbeat (R-R) interval series of 10 healthy subjects (21-56 years). Our innovation is twofold: (i) we quantified instances of low-dimensional chaos, random fluctuations, and those for which our method failed to provide either (due to poor statistics); (ii) consecutive subepochs of PD2s underwent a relative dispersion (RD) analysis, yielding an index (D) which quantifies the dynamical organization of the heart rate generator. RESULTS: The mean values of PD2 series varied between 4.58 and 5.88 (mean+/-SD= 5.21+/-0.41, n = 10). For group 1 (21-30 years, n = 6) we found an averaged PD2 of 5.49+/-0.27, while for group 2 (47-56 years, n = 4) PD2 averaged 4.79+/-0.17. The RD analysis performed for subepochs of PD2s yielded both instances obeying fractal scaling (D < 1.5) and stochasticity (D > 1.5). The average D for group 1 was 1.39+/-0.04 (14 subepochs) and for group 2, 1.20+/-0.008 (8 subepochs). Paired t-test and Hartley F-max test for comparison between D values and homogeneity of variance between the two groups were performed, yielding P-values 0.004 and 0.02, respectively. CONCLUSIONS: The complexity of the HRV seems to be modulated by a non-random fractal mechanism of a 'hyperchaotic' system, i.e. it can be hypothesized to contain more than one attractor. Also, our results support the 'chaos hypothesis' put forth recently, namely, the complexity of the cardiovascular dynamics is reduced with aging. The index of relative dispersion of the dimensional complexity has to be tested in various clinico-pathological settings, in order to corroborate its value as a potential new physiological measure.

Serum amyloid type A may be a predictor of restenosis.

BACKGROUND: Elevation of acute phase proteins [C-reactive protein (CRP) and serum amyloid type A (SAA)] has been demonstrated in unstable angina with an adverse clinical prognosis. HYPOTHESIS: The study was undertaken to determine the effect of angioplasty on the levels of SAA and the correlation with postangioplasty restenosis. METHODS: In a university-affiliated tertiary medical center, a prospective case study was undertaken in 55 patients who underwent successful percutaneous transluminal coronary angioplasty (PTCA) of a single coronary lesion for angina pectoris. Three groups of patients were clinically characterized according to Braunwald's classification of anginal syndrome: Group A: class III; Group B: class I; Group C: stable angina. Serum amyloid type A was measured by an ELISA method before PTCA and after 24 h, 1, and 3 months. Patients were followed clinically for 12 months. A thallium stress perfusion scan was performed 3 months after PTCA and coronary angiography was repeated in patients with an abnormal thallium perfusion scan. RESULTS: Serum amyloid type A levels > 100 micrograms/ml could identify Group A patients with a high sensitivity and specificity (r = 0.85 and 0.86, respectively). Of the patients studied, 75% increased their SAA level 24 h after angioplasty. An increase of SAA by > 100% was associated with an increased risk of restenosis, with a relative risk of 6.4 (p < 0.05). CONCLUSION: Increased levels of SAA characterize patients with unstable angina pectoris with a high specificity and sensitivity. Levels of SAA that increase > 100% 24 h after angioplasty may serve as a marker of restenosis.