Abnormal Typical Pattern of Platelet Function and Thromboxane Generation in Unstable Angina

Platelet aggregation (PA), platelet thromboxane B2 (TXB2) generation and 14C 5-hydroxytryptamine (5HT) release were studied in 13 patients with unstable angina, and compared to 14 patients with stable angina and 16 healthy controls. A typical pattern, distinct in 4 aspects from stable angina patients or controls, was observed in the unstable angina patients. ADP or collagen induced shape change was 3-4 times greater, the extent of epinephrine induced PA was nil or very low, the extent of collagen induced 14C 5HT release was also reduced while collagen induced platelet TXB2 generation was increased in spite of a reduced extent of PA. The extent of ADP or collagen induced PA was also significantly reduced. These results indicate a platelet membrane abnormality occurring presumably during contact of the circulating platelets with a non-occlusive thrombus observed at sites of ruptured plaques in unstable angina patients. Since also the pattern (20-30% overlap with control values) was distinct from that of stable angina patients, it might indicate an active thrombotic process.

Plasma β-thromboglobulin (βTG) and TXB2 levels and serum TXB2 generation were also studied in the cardiac patients and controls and in another 10 patients with advanced peripheral occlusive arterial disease (POAD). Plasma βTG and TXB2 levels were slightly elevated in the unstable angina patients and markedly elevated in the POAD patients. Serum TXB2 generation was, however, elevated in the stable angina patients (p <0.002) and more so in the unstable angina patients (p <0.001) compared to controls or to POAD patients. This was presumably mediated through enhanced thrombin generation. These results suggest that the measured plasma βTG variable in the unstable angina patients is not useful in the assessment of in vivo platelet activation. It is presumably reflecting the sum of local enhanced platelet activation (at sites of ruptured plaques) and of reduced function of the “defective” circulating platelets. The ability of the platelets of unstable angina patients to generate large amounts of TXB2 if occurring in vivo might induce an intense coronary vasospasm.

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.

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.

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 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 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.

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.

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 (</= 3 years old) were not pause dependent, while female sex correlated with pause dependent torsade. Using multivariate analysis, age was the only independent predictor of the mode of onset of torsade de pointes.

CONCLUSION

Available data suggest that the majority of spontaneous arrhythmias in the congenital long QT syndrome are pause dependent. Torsade de pointes that is not preceded by pauses appears to be limited to patient subgroups with severe forms of the disease, like symptomatic infants. These findings have important implications regarding the use of cardiac pacing for arrhythmia prevention.

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.

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.

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.

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.

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.

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.

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.

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, </=6 minutes) led to device success in 14 (70%) of the patients and residual stenosis of 65+/-28%. Procedural success was obtained in 13 (65%) of the patients, with a final residual stenosis of 5+/-8%. There was a low rate of device-related adverse events: 1 patient (5%) had a non-Q-wave myocardial infarction, and distal embolization was noted in 1 patient (5%). Adjunct PTCA or stenting was used in all patients. There were no serious adverse events during hospitalization.

CONCLUSIONS

Ultrasound thrombolysis in thrombus-rich lesions in SVGs offers a very promising therapeutic option.

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.

Transient bradycardia induced by carotid sinus pressure increases outflow obstruction in hypertrophic obstructive cardiomyopathy but not in valvular aortic stenosis

BACKGROUND

The murmur of hypertrophic obstructive cardiomyopathy (HOCM) increases in intensity in about 80% of those patients in whom carotid sinus pressure (CSP) slows the heart rate. This does not occur in valvular aortic stenosis (AS). STUDY OBJECTIVES, DESIGN, AND PATIENTS: It was hypothesized that left ventricular (LV) obstruction increases with CSP in HOCM and not in AS. Furthermore, it was not clear whether it was the sudden bradycardia or CSP itself that was responsible for the effect noted. Therefore, studies were performed using two different interventions: (1) Doppler echocardiography was performed before and during CSP in 36 HOCM patients and 21 AS patients; (2) two patients with DDD pacemakers and HOCM were examined before and after pacemaker rate slowing. Finally, atrial pacing was performed in three HOCM patients at catheterization, and atrial pacing was either slowed or stopped (without CSP).

RESULTS

LV outflow velocity and pressure gradient increased in 28 of 30 HOCM patients (92%) in whom heart rate decreased with CSP. The peak instantaneous pressure gradient increased from 45+/-37 to 77+/-53 mm Hg (p<0.005), and the velocity contour became more typical of HOCM. The pressure gradient increased from 30 mm Hg to 64 and 81 mm Hg, respectively, in the two patients with DDD pacemakers after pacemaker rate slowing. Similar results were seen with slowing or cessation of atrial pacing at catheterization. In contrast, the pressure gradient increased in only three of 21 AS patients (14%), to 44+/-28 from 41+/-25 mm Hg, and remained unchanged in the other 18.

CONCLUSION

This study shows that LV outflow velocity and pressure gradient increase markedly in most HOCM patients (92%) if CSP succeeds in slowing the heart rate, but not in patients with valvular AS. A similar effect is obtained by simply decreasing the atrial rate in patients with DDD or atrial pacemakers. This increase in outflow tract obstruction is sufficient to account for the increase in murmur intensity. Decreased afterload (secondary to greater aortic decompression with the longer diastole), increased intrinsic force of contraction with the bradycardia (the Woodworth effect), and Starling's law may play independent roles in the dynamic increase in obstruction observed during CSP in patients with HOCM. Worsening of mitral regurgitation was not clearly shown to contribute to the increase in murmur, but it cannot readily be ruled out.

Noninvasive diagnosis of dual AV node physiology in patients with AV nodal reentrant tachycardia by administration of adenosine-5'-triphosphate during sinus rhythm

BACKGROUND

Atrioventricular nodal reentry tachycardia (AVNRT) represents the most commonly encountered type of regular paroxysmal supraventricular tachycardia. This study determined whether administration of adenosine-5'-triphosphate (ATP) during sinus rhythm may be useful in the noninvasive diagnosis of dual AV nodal pathways.

METHODS AND RESULTS

During electrophysiological study, we intravenously administered incremental doses of ATP (from 10 to 50 mg) during sinus rhythm to patients with spontaneous and inducible sustained AVNRT (study group, n=42) and to patients with no evidence of dual AV nodal physiology or inducible AVNRT (control group, n=21). Signs suggestive of dual AV node physiology after ATP administration during sinus rhythm ("jump" of AH > or =50 ms between 2 consecutive beats, > or =1 AV nodal echo beat, or initiation of AVNRT) were observed in 32 (76%) of 42 study patients but in only 1 (5%) of the 21 control patients (P<0.001). Similar results were observed when only surface lead recordings (without intracardiac recordings) were evaluated. Signs suggestive of dual AV node physiology by the ATP test were observed in 29 (80.5%) of 36 patients who had electrophysiological demonstration of dual AV node physiology and in 3 (50%) of 6 patients without AV nodal duality (P=NS). Signs suggestive of dual physiology according to the ATP test disappeared in 11 (92%) of the 12 patients who underwent successful slow AV nodal ablation but persisted in 8 (62%) of 13 patients who underwent AV nodal modification.

CONCLUSIONS

Administration of ATP during sinus rhythm may be a useful bedside test for identifying patients with dual AV nodal pathways who are prone to AVNRT. This simple test should be considered as a screening test for patients with symptoms suggestive of paroxysmal supraventricular tachycardia but no documented arrhythmias or for patients with documented narrow complex tachycardia of unclear mechanism.

Hemodynamic changes determine the efficacy of thrombolysis: results from an in-vitro flow model

BACKGROUND

The efficacy of thrombolytic therapy might be influenced by changes in the hemodynamic status. The aim of the study was to examine whether changes in perfusion pressure could affect the time to reflow in an in-vitro model.

METHODS

The in-vitro flow system comprised flexible plastic tubes that enclosed a blood clot formed in one of the circuit arms. Streptokinase (125,000 U) or saline (control) was injected from a proximal side branch to induce thrombolysis. The protocol comprised four treatments: A, perfusion pressure 150/90 mmHg with streptokinase infusion; B, perfusion pressure 150/90 mmHg with saline; C, perfusion pressure 120/60 mmHg with streptokinase; D, perfusion pressure 120/60 mmHg with saline. Reflow was defined as flow restoration determined by the ultrasonic flowmeter.

RESULTS

Successful recanalization was obtained in six of six samples subjected to treatment A (100%), two of seven samples subjected to treatment B (28%), three of five samples subjected to treatment C (60%) and none of six samples subjected to treatment D (0%). Time to reflow was 23 +/- 11 min with treatment A, 76 +/- 24 min with treatment B, 66 +/- 25 min with treatment C, and > 90 min with treatment D.

CONCLUSIONS

Our data suggest that the hemodynamic status determines the efficacy of streptokinase-induced thrombolysis, and that spontaneous clot lysis is more likely to occur at greater perfusion pressures. It is conceivable that the hypotensive reaction induced by streptokinase in the clinical setting may adversely affect angiographic patency, compared with that observed with other lytic agents such as tissue-type plasminogen activator.

High anti-cytomegalovirus (CMV) IgG antibody titer is associated with coronary artery disease and may predict post-coronary balloon angioplasty restenosis

Recent studies have demonstrated that cytomegalovirus (CMV) DNA was found in atherosclerotic coronary arteries in restenotic lesions, and prior infection with CMV could be a strong independent risk factor for restenosis after coronary atherectomy. We studied the correlation between anti-CMV antibody titer and coronary artery disease. Sixty-five patients (50 men and 15 women) with coronary artery disease were enrolled prospectively. All had symptomatic coronary artery disease with an angiographic documentation of a de novo single coronary lesion. All underwent balloon coronary angioplasty and were followed for 12 months with a thallium perfusion scan 3 months after angioplasty. Patients who had recurrent chest pain and/or a positive thallium scan had another coronary angiography. Blood samples were taken before angiography and 1 and 3 months later. Patients with high anti-CMV titer > or = 1:800 had a higher prevalence of coronary artery disease (p <0.001) than seropositive patients with a lower antibody titer (< or = 1:400); patients with high antibody titer (> or = 1:800) had a higher restenosis rate than seropositive patients with a low antibody titer (< or = 1:400) (p <0.05). High antibody titers against CMV (IgG) may be a strong marker for coronary artery disease, and might predict post-coronary angioplasty restenosis. These findings support the infectious theory of atherosclerosis (especially with prior CMV infection), and also suggest that a chronic immunologic response has a role in atherosclerosis and restenosis.

Calcium channel blocking agents and risk of cancer in patients with coronary heart disease. Benzafibrate Infarction Prevention (BIP) Study Research Group

OBJECTIVES

This analysis sought to estimate the risk ratio for cancer incidence and cancer-related mortality associated with the use of calcium channel blocking agents (CCBs) in a large group of patients with chronic coronary heart disease (CHD).

BACKGROUND

Recent publications contend that the use of short-acting CCBs may double the risk of cancer incidence and possibly increase mortality in hypertensive patients.

METHODS

Cancer incidence data were obtained for 11,575 patients screened for the Bezafibrate Infarction Prevention (BIP) study, one-half of whom were treated at the time of screening with CCBs, over a mean follow-up period of 2.8 years. Cause-specific mortality was available through September 1996 (mean follow-up 5.2 years). The statistical power of detecting an odds ratio > or = 1.5 (given the cancer incidence rate of 2.1 in the nonusers of CCBs) was 0.91. The power declined to 0.77, 0.54 and 0.41, with declining odds ratios of 1.4, 1.3 and 1.25, respectively.

RESULTS

Of 246 incident cancer cases, 129 occurred among the users (2.3%) and 117 among nonusers of CCBs (2.1%). After adjustment for age, gender and smoking, the odds ratio estimates for all cancers combined was 1.07 (95% confidence interval [CI] 0.83 to 1.37) for CCB users relative to nonusers. The adjusted risk ratio for all-cause mortality for age, gender and smoking and pertinent prognostic clinical characteristics was estimated at 0.94 (95% CI 0.85 to 1.04). The adjusted risk ratio for cancer-related mortality was 1.03 (95% CI 0.75 to 1.41).

CONCLUSIONS

Patients with CHD treated with CCBs exhibited a similar risk of cancer incidence and total and cancer-related mortality compared with nonusers of CCBs. This analysis provides a certain assurance that CCB use in middle-aged and elderly patients with CHD is not associated with a meaningful difference in cancer incidence and related mortality.

Autoimmune and inflammatory responses may have an additive effect in postpercutaneous transluminal coronary angioplasty restenosis

Patients who had an increase in their serum amyloid type A level of > 100% in the first 24 hours after percutaneous transluminal coronary angioplasty (PTCA) and also developed a positive antibody result (antinuclear factor or anticardiolipin), had a relative risk of 10.6 for developing restenosis in the first year after PTCA.

Mode of onset of malignant ventricular arrhythmias in idiopathic ventricular fibrillation

INTRODUCTION

The mode of onset of malignant ventricular arrhythmias (ventricular tachycardia [VT] or ventricular fibrillation [VF]) has been well described in patients with organic heart disease and in patients with the long QT syndromes. Less is known about the mode of onset of VF in patients with out-of-hospital VF who have no evidence of organic heart disease or identifiable etiology.

METHODS AND RESULTS

We reviewed the ECGs of all our patients with idiopathic VF. Documentation of the onset of spontaneous arrhythmias was available for 22 VF episodes in 9 patients (6 men and 3 women; age 41 +/- 16 years). In all instances, spontaneous VF followed a rapid polymorphic VT, which was initiated by premature ventricular complexes (PVCs) with very short coupling intervals. The PVC initiating VF had a coupling interval of 302 +/- 52 msec and a prematurity index of 0.4 +/- 0.07. These PVCs occurred within 40 msec of the peak of the preceding T wave. Pause-dependent arrhythmias were never observed.

CONCLUSION

Cardiac arrest among patients with idiopathic VF has a very distinctive mode of onset. Documentation of a polymorphic VT that is not pause dependent is of diagnostic value.

The CB-12L: a new device for transtelephonic transmission of a 12-lead electrocardiogram

The value of transtelephonic transmission of ECG information is well established, and technological advances have continuously provided improved state-of-the-art equipment. Shahal Medical Services provides professional care to subscribers who call the medical center and describe their symptoms, whereupon therapeutic measures are decided upon. A new 12-lead patient controlled device for telephonically transmitting an ECG (GB-12L) has become available; the aim of this study was to evaluate its accuracy and practicability. Forty tracings (20 standard ECG tracings obtained under medical supervision in the physician's office and 20 by the patient in his home using the new CB-12L ECG device and transmitted by telephone to the center) from 20 subjects with various electrocardiographic pathologies were reviewed by 19 experienced physicians who were asked to interpret the results and identify the recording device. In 82% of the possibilities, the interpretation of the tracings was identical for both those recorded by the standard ECG recorder and the CB-12L ECG. An equal number of physicians could not identify the means by which device the tracings were taken. Proper placement of the electrodes did not prove to be a problem for the patient. Thus, the CB-12L ECG was found to be an easily operable and reliable tool which may be of value for early and prompt diagnosis of threatening cardiac situations in the prehospital setting.

Analysis of coronary ultrasound thrombolysis endpoints in acute myocardial infarction (ACUTE trial). Results of the feasibility phase

BACKGROUND

It has been demonstrated that therapeutic ultrasound effects ultrasound thrombolysis by selectively disrupting the fibrin matrix of the thrombus. This study was conducted to evaluate the clinical feasibility of percutaneous transluminal coronary ultrasound thrombolysis in acute myocardial infarction (AMI).

METHODS AND RESULTS

Consecutive patients (n = 15) with evidence of anterior AMI and Thrombolysis in Myocardial Infarction (TIMI) grade 0 or 1 flow in the left anterior descending artery underwent coronary ultrasound thrombolysis. Angiographic follow-up was performed after 10 minutes and 12 to 24 hours. Ultrasound induced successful reperfusion (TIMI grade 3 flow) in 87% of the patients. Adjunct percutaneous transluminal coronary angioplasty (PTCA) after ultrasound thrombolysis produced a final residual stenosis of 20 +/- 12% as determined by quantitative coronary angiographic analysis. There were no adverse angiographic signs or clinical effects during the procedure. There was no change in the degree of flow in any of the patients at the 12- to 24-hour angiograms. During hospitalization, 1 patient had recurrent ischemia on the fifth day after the procedure, and emergent catheterization revealed occlusion at the treatment site. The patient was successfully treated with PTCA.

CONCLUSIONS

These results suggest that ultrasound thrombolysis has the potential to be a safe and effective catheter-based therapeutic modality in reperfusion therapy for patients with AMI and other clinical conditions associated with intracoronary thrombosis.

Usefulness of self-administration of intramuscular lidocaine in the prehospital setting for ventricular tachyarrhythmias unassociated with acute myocardial infarction (the "Shahal" experience in Israel)

We report on the experience accumulated by the subscribers of SHAHAL cardiac services who self-injected intramuscular lidocaine (using an automatic injector "LidoPen") for documented ventricular tachyarrhythmias which were not associated with an acute myocardial infarction. SHAHAL provides professional care to its subscribers who telephone a monitor center and describe their symptoms, whereupon therapeutic measures are decided upon. Patient data are stored in a central computer, and the center can dispatch mobile intensive care units. All subscribers carry a portable transtelephonic electrocardiographic transmitter and are provided with the LidoPen. Indications for self-injection were: transmission of a wide-QRS tachycardia (rate > 100 beats/min), symptomatic multiple or complex ventricular premature complexes in association with chest discomfort, and when the time of arrival of a medical team to the patient was estimated to be at least 8 to 10 minutes. Successful usage of the LidoPen was reported in 137 cases (123 patients). An additional 11 patients failed to use the injector properly. There was a success rate in abolishing rapid sustained ventricular tachycardia (27 of 76 patients) and nonsustained ventricular tachycardia and/or multiple and complex ventricular ectopic activity (8 of 30 patients) of 33% (total 35 of 106 patients). In another 9%, those arrhythmias were slowed markedly. The remaining 31 cases were eventually interpreted as being of supraventricular origin. No complications attributed to the use of the injector were reported and its use was found to be both feasible and effective in the prehospital setting.

Changes in hemostatic function at times of cyclic variation in occupational stress

In this study we demonstrated, in the same healthy subjects, a significant elevation in coagulation factors VII and VIII, fibrinogen, thrombocyte count, and thrombin and adenosine diphosphate-induced platelet aggregation during a period of increased workload compared with a calm work period. These findings may add to the understanding of the mechanism that links mental stress to coronary disease.

Enhancement of recombinant tissue-type plasminogen activator thrombolysis with a selective factor Xa inhibitor derived from the leech Hirudo medicinalis: comparison with heparin and hirudin in a rabbit thrombosis model

OBJECTIVE

To compare the efficacy of Yagin, a factor Xa inhibitor derived from the leech Hirudo medicinalis, with those of heparin and hirudin as adjuncts to recombinant tissue-type plasminogen activator (rTPA) thrombolysis in a rabbit thrombosis model.

METHODS

Thirty-one animals were allocated randomly to three groups, all administered four boluses of 0.25 mg/kg rTPA every 10 min for 30 min, 17 mg/kg aspirin intravenously, and heparin (as a 100 IU/kg bolus followed by infusion of 50 IU/kg heparin per h), hirudin (as a 2 mg/kg bolus followed by infusion of 1 mg/kg hirudin per h), or Yagin (as an 80 micrograms/kg bolus followed by infusion of 43 micrograms/kg Yagin per h).

RESULTS

Administration of Yagin was associated with a significant acceleration of the reflow time, this time being 14.5 +/- 1.2 min with Yagin, 25.8 +/- 5.2 min with heparin (P < 0.0001, versus Yagin), and 28.7 +/- 16.0 min with hirudin (P = 0.012, versus Yagin). Overall patency did not differ significantly among the three groups.

CONCLUSIONS

At the indicated single doses, inhibition of factor Xa by a relatively low concentration of Yagin was found to be superior than that with either heparin or hirudin for accelerating rTPA thrombolysis.

Calcium antagonists and mortality in patients with coronary artery disease: a cohort study of 11,575 patients

OBJECTIVES

This study sought to establish the risk ratio for mortality associated with calcium antagonists in a large population of patients with chronic coronary artery disease.

BACKGROUND

Recent reports have suggested that the use of short-acting nifedipine may cause an increase in overall mortality in patients with coronary artery disease and that a similar effect may be produced by other calcium antagonists, in particular those of the dihydropyridine type.

METHODS

Mortality data were obtained for 11,575 patients screened for the Bezafibrate Infarction Prevention study (5,843 with and 5,732 without calcium antagonists) after a mean follow-up period of 3.2 years.

RESULTS

There were 495 deaths (8.5%) in the calcium antagonist group compared with 410 in the control group (7.2%). The age-adjusted risk ratio for mortality was 1.08 (95% confidence interval [CI] 0.95 to 1.24). After adjustment for the differences between the groups in age and gender and the prevalence of previous myocardial infarction, angina pectoris, hypertension, New York Heart Association functional class, peripheral vascular disease, chronic obstructive pulmonary disease, diabetes and current smoking, the adjusted risk ratio declined to 0.97 (95% CI 0.84 to 1.11). After further adjustment for concomitant medication, the risk ratio was estimated at 0.94 (95% CI 0.82 to 1.08).

CONCLUSIONS

The current analysis does not support the claim that calcium antagonist therapy in patients with chronic coronary artery disease, whether myocardial infarction survivors or others harbors an increased risk of mortality.

Reduction of reinfarction and angina with use of low-molecular-weight heparin therapy after streptokinase (and heparin) in acute myocardial infarction

This study examined whether extending the anticoagulation effect of heparin by low-molecular-weight heparin (clexane) can prevent recurrent myocardial infarction (AMI) treated by streptokinase. On the fifth day after AMI and after heparin therapy cessation, 103 patients were randomly assigned to either treatment with low-molecular-weight heparin (40 mg subcutaneously per day for 25 days, n=43) or control (no treatment, n=60). All patients were followed carefully for 6 months after the infarction date. A total of 32 patients (31%) sustained a cardiac event during the 6-month observation period. There were 12 patients (20%) with reinfarction in the control group versus 2 patients (4.6%) in the low-molecular-weight heparin group during the first 30 days of the study (p=0.02). One additional patient sustained reinfarction at 3 months of followup in the control group, which yielded a total of 13 patients (21.6%) sustaining reinfarction in the control group versus 2 patients (4.6%) in the low-molecular-weight heparin group during 6 months of followup (p=0.01). Angina pectoris after AMI was diagnosed in 13 control patients (21.6%) versus 4 low-molecular-weight heparin-treated patients (9.3%) (p=0.078) during the study period. No major bleeding events were reported in either low-molecular-weight heparin-treated or control patients. Among patients with recently diagnosed AMI treated by streptokinase, extending the anticoagulant effect of heparin for 25 days may prevent recurrent coronary events for at least one month.

High-dose intravenous magnesium attenuates complement consumption after acute myocardial infarction treated by streptokinase

OBJECTIVE

This study was designed to detect changes in complement levels following acute myocardial infarction and to test whether magnesium sulphate (MgSO4) administration interferes with the complement response that follows acute myocardial infarction.

DESIGN

Twenty-nine patients with acute myocardial infarction treated with streptokinase were included and randomly assigned to three treatment groups. In groups A and B, a bolus of 1 g MgSO4 was infused intravenously followed by 4 g (group A) and 14 g (group B) MgSO4 for 24 h while normal saline was administered in group C (control). Blood samples for C3, C4 and CH-100 were obtained at baseline and repeatedly during the 48 h following the initiation of magnesium infusion.

RESULTS

In groups A and C, a remarkable decrease in the levels of C3, C4 and CH-100 was observed when measured 1 h after the end of streptokinase infusion and thereafter for the ensuing 48 h compared to baseline values (P < 0.05). In group B, the decrease in these complement elements was attenuated, and a significant (P < 0.05) delayed decrease of C3 and C4 was observed only at 24 h and later up to 48 h. The mean level of CH-100 in group B was significantly depressed compared to baseline from 3 h and thereafter up to 48 h. Mean C3 values plotted against observation time differed between the three groups (P = 0.021). A similar trend was observed for C4 (P = 0.133) but not for CH-100 (P = 0.46).

CONCLUSION

(1) Complement elements are being consumed following acute myocardial infarction treated by streptokinase. (2) High-dose intravenous magnesium attenuates the complement process following acute myocardial infarction. (3) These results might signify that magnesium modulates the inflammatory response that follows infarction.

Improvement of cardiac performance by intravenous infusion of L-arginine in patients with moderate congestive heart failure

OBJECTIVES

The aim of this study was to evaluate the hemodynamic effect of L-arginine infusion in patients with congestive heart failure.

BACKGROUND

Endothelium-dependent vasodilation is impaired in patients with congestive heart failure. Nitric oxide, which was identified as endothelium-derived relaxing factor, is generated by nitric oxide synthase from L-arginine. Our hypothesis was that administration of L-arginine in patients with congestive heart failure may increase nitric oxide production and have a beneficial hemodynamic effect.

METHODS

Twelve patients with congestive heart failure (New York Heart Association class II or III) due to coronary artery disease (left ventricular ejection fraction < 35%) were given 20 g of L-arginine by intravenous infusion over 1 h at a constant rate. Stroke volume, cardiac output and left ventricular ejection fraction were determined with Doppler echocardiography at baseline and at 30 and 60 min and 1 h after the end of infusion. Blood and urinary levels of nitrite/nitrate (NO2/NO3), stable metabolites of nitric oxide, were measured and clearance was calculated.

RESULTS

One hour of infusion of L-arginine resulted in a significant increase in stroke volume (from 68 +/- 18 ml to 76 +/- 23 ml [mean +/- SD], p = 0.014) and cardiac output (from 4.07 +/- 1.22 liters/min to 4.7 +/- 1.42 liters/min, p = 0.006) without a change in heart rate. Mean arterial blood pressure decreased (from 102 +/- 11 mm Hg to 89 +/- 9.5 mm Hg, p < 0.002), and systemic vascular resistance decreased significantly. Within 1 h after cessation of L-arginine infusion, blood pressure, stroke volume, cardiac output and systemic vascular resistance were statistically not different from baseline values. Clearance of NO2/NO3 increased significantly during L-arginine administration (from 13.28 +/- 0.42 ml/min to 29.97 +/- 1.09 ml/min, p < 0.001).

CONCLUSIONS

Infusion of L-arginine in patients with congestive heart failure results in increased production of nitric oxide, peripheral vasodilation and increased cardiac output, suggesting a beneficial hemodynamic and possibly therapeutic profile.

Right bundle branch block of unknown age in the setting of acute anterior myocardial infarction: an attempt to define who should be paced prophylactically

It is widely accepted that patients presenting with acute anterior myocardial infarction and acute onset of right bundle branch block should be prophylactically paced in contrast with those who have a chronic bundle branch block. The admitting physician is faced with the dilemma of how to act if the age of this conduction disturbance is unknown. This problem has further intensified in recent years, with the introduction of thrombolytic treatment, where insertion of a central vascular line is associated with increased morbidity. The objectives of this study were to define clinical or electrocardiographic parameters that may help the admitting physician to decide whether patients presenting with an anterior wall myocardial infarction and a right bundle branch block of unknown age should be prophylactically paced. We examined prospectively the in-hospital clinical course of 39 consecutive patients presenting with an acute myocardial infarction in whom the age of a right bundle branch block upon admission was unknown (group C, n = 39) and compared with two similar groups of patients who presented with an acute right bundle branch block (group A, n = 38) and with a known chronic right bundle branch block (group B, n = 22). Thirty-three patients (33%) died, with cardiogenic shock being the leading cause of death in the entire population. Prophylactic pacing, which was carried out in 66% and 54% of patients in groups A and C, respectively, did not reduce mortality rates. No clinical or electrocardiographic variables on admission were predictive to support prophylactic pacing in group C. In 10 of 46 (22%) patients who were prophylactically paced with a transvenous electrode, the following complications attributed to the procedure were detected: (1) either rapid sustained ventricular tachycardia (during implantation) that was unresponsive to overdrive pacing, or ventricular fibrillation necessitating electrical defibrillation (4 patients); (2) recurrent episodes of rapid nonsustained ventricular tachycardia, which stopped only after the pacemaker was turned off (1 patient); (3) complete AV block (1 patient); (4) fever appearing on the third or fourth day after implantation (3 patients); and (4) a large hematoma in the groin in 1 patient who was treated with thrombolysis shortly before pacemaker electrode insertion. Thus, the complications of transvenous temporary pacing in the era of thrombolysis may outweight any theoretical advantage.

Safety of coronary ultrasound angioplasty: effects of sonication on intact canine coronary arteries

The purpose of this work was to examine in vivo the safety of sonication in the coronary arteries in a live animal model. In intact dogs (n = 8), balloon dilatation was performed on the proximal left anterior descending artery (LAD) followed by sonication to the left circumflex artery (LCX) in power levels found to be optimal for thrombus ablation. Post-dilatation and post-ultrasound coronary angiography, echocardiography, histopathology, CK-MB, indices of hemolysis, and coagulation were compared. Sonication did not induce changes in the ECG or blood pressure. Coronary angiography revealed no adverse side effects or change in arterial diameter (2.3 +/- 0.7 vs. 2.4 +/- 0.3 mm). Echocardiography showed transient opacification of the myocardium. Histopathology revealed a comparable minimal degree of endothelial denudation. After sonication there were no changes in the level of CK-MB (312 +/- 168 vs. 283 +/- 207 IU), hemoglobin (11.3 +/- 0.9 vs. 12.7 +/- 1.1 gr%), haptoglobin (479 +/- 136 vs. 451 +/- 121 mg/dL), fibrinogen (142 +/- 18 vs. 165 +/- 28 mg%), partial thromboplastin time (17.3 +/- 3.2 vs. 17.6 +/- 3.4 sec), prothrombin time (13.3 +/- 7.8 vs. 11.5 +/- 2.9 sec), and degree of platelet aggregation (55 +/- 17 vs. 62 +/- 8%). Thus, the data suggest that transluminal coronary sonication exerts no overt adverse effects in vivo.

Treatment with beta-adrenergic blocking agents after myocardial infarction: from randomized trials to clinical practice

OBJECTIVES

Our aim was to determine the percent of patients with myocardial infarction who are treated with beta-adrenergic blocking agents in dosages proved to be effective in preventing death after a heart attack.

BACKGROUND

In the prospective randomized trials showing that beta-blocker treatment improves survival rates after myocardial infarction, relatively high dosages of these agents were used. However, it is not known whether these dosages are used in current clinical practice.

METHODS

In a retrospective analysis of clinical data from 606 consecutive survivors of myocardial infarction at four university hospitals in three countries, we assessed the number of infarct survivors receiving prospectively defined "effective dosages" of beta-blockers. We defined these dosages as those that demonstrated improved survival rates of infarct survivors who received active drug in large, prospective, double-blind, placebo-controlled trials.

RESULTS

Only 58% of infarct survivors with no contraindications to beta-blockers received these drugs at the time of hospital discharge, and only 11% received dosages equivalent to > 50% of the effective dosages. Independent predictors of failure to prescribe beta-blockers to infarct survivors without contraindications to these drugs were the use of diuretic agents, transient heart failure, impaired left ventricular function and increased patient age. Among patients receiving beta-blockers, only the use of propranolol predicted prescription of a low beta-blocker dosage.

CONCLUSIONS

Failure to prescribe beta-blockers after myocardial infarction is common but in most cases is not due to clear contraindications. Many patients not receiving beta-blockers belong to subgroups that would derive the greatest benefit from such treatment. Finally, even when beta-blockers are prescribed, the dosages used are considerably lower than those proved to be effective in preventing death after myocardial infarction.

Study of the mechanism of ultrasound angioplasty from human thrombi and bovine aorta

Ultrasound angioplasty is a newly developed technology for percutaneous arterial recanalization. Data suggest that ultrasound is particularly effective in ablating fresh thrombi. Arterial walls were found to be resistant to ultrasound ablation. Thrombi, aortic wall segments, and hydroxyproline gelatin were studied in vitro to determine their respective ablation rates. The elasticity of the samples was determined in a force-mode apparatus. The cavitation threshold was determined in an arterial phantom apparatus. Thrombi displayed ablation rates that were > 20 times higher than those of aortic wall samples (591 +/- 82 vs 25 +/- 14 mg/s, p < 0.001). The differences in ablation rates were accompanied by significantly lower elasticities in the thrombus group compared with those in the aortic wall group (0.16 +/- 0.05 vs 312 +/- 37 g/cm2, p < 0.001). Experiments with hydroxyproline gelatin suggest a negative correlation (r = -0.90) between elasticity and ultrasound ablation. Ultrasound ablation of thrombi was evident only above the cavitation threshold. Thus, ultrasound angioplasty has the potential to induce the selective injury required for successful transluminal intervention in the treatment of thrombus-rich lesions.

Effect of magnesium on restenosis after percutaneous transluminal coronary angioplasty: a clinical and angiographic evaluation in a randomized patient population. A pilot study. The Ichilov Magnesium Study Group

Restenosis is a major clinical problem following successful percutaneous transluminal coronary angioplasty. Since magnesium has vasodilator and antithrombotic effects, this study was designed to evaluate its potential to decrease the rate of restenosis. In an open-labelled, randomized controlled study, 148 patients underwent successful coronary angioplasty. Ninety-eight patients were treated with 46-52 mmol/18-20 h intravenous magnesium sulphate (groups M1 and M2), and 49 of them continued with oral supplements of magnesium hydroxide 600 mg.day-1 (group M2). The other 50 patients served as controls (group C). Coronary angiography was performed before, immediately after and at 6 months follow-up or earlier if clinically indicated. Clinical, laboratory, ergometric and radionuclide evaluations were also carried out. One hundred and thirty-nine patients (94%) with 163 dilated segments completed the study. Intravenous magnesium was well tolerated. The cross-sectional area at the site of angioplasty increased by 3.55 +/- 2.01 mm2 in groups M1 and M2 compared with an increase of 2.90 +/- 1.63 mm2 in the control group, (P = 0.03). A trend towards a lower rate of restenosis (> 50% reduction in luminal diameter) was noticed in the magnesium groups (28/110, 25%) compared with the control group (20/53, 38%) P = 0.10. Oral administration of magnesium was well tolerated, did not have an additive effect on restenosis, but an improved clinical course was noted. It is concluded that intravenous administration of magnesium in patients undergoing coronary angioplasty is feasible and safe and that the beneficial trend of magnesium to prevent acute recoil and late (within 6 months) restenosis is encouraging and should promote further investigation in a larger patient population.

Serum lipids and restenosis after successful percutaneous transluminal coronary angioplasty. Ichilov Magnesium Study Group

The effects of plasma lipids on the clinical and angiographic parameters of 134 patients, in whom coronary angioplasty was performed in 157 vessels, were prospectively examined. During a 6-month follow-up, restenosis was detected angiographically in 39 patients (29%; 45 vessels). None of the clinical, biochemical, or angiographic variables examined was predictive of stenosis and the tendency of a vessel to restenose was not patient-dependent but rather lesion-related. However, restenosis developed in 31 of 102 vessels (30%) in patients with high-density lipoprotein (HDL) cholesterol < or = 40 mg/dl, compared with restenosis in 10 of 55 vessels (19%) in patients with HDL cholesterol > 40 mg/dl (p = 0.092). No significant differences were observed when restenosis rates were compared in patients with total cholesterol levels > 250 mg/dl or < 250 mg/dl; no differences were seen in low-density lipoprotein (LDL) cholesterol levels when comparing patients with > 160 mg/dl and < 160 mg/dl. In 117 patients (132 vessels), complete serial blood specimens were obtained until the concluding angiography at 6 months. During follow-up, both groups (those with and without restenosis) had almost similar findings. Triglycerides decreased equally in both groups, and total cholesterol increased mildly in those who had restenosis; HDL and LDL cholesterol levels increased significantly in each group. No significant differences were observed with respect to extent of these changes between the groups. Thus, although lipid levels at the time of angioplasty and at 6 months follow-up were not found to predict the occurrence of restenosis, the association of low high-density lipoprotein levels and the tendency for restenosis should not be overlooked.