Congenital coronary artery anomalies in adults: non-invasive assessment with multidetector CT

Congenital coronary anomalies (CCAs) are uncommon but can cause sudden cardiac death or other symptoms of myocardial ischaemia, especially in young healthy subjects. Conventional coronary angiography (CA) is an invasive and expensive procedure, and cannot provide three-dimensional data on the anomalous vessel. Electrocardiographic gated multidetector CT (MDCT) has been reported to be useful for non-invasive evaluation of CCAs. The purpose of this pictorial review is to discuss and illustrate different CCAs in terms of clinical importance, type and manifestations using MDCT. Knowledge of the CT appearances and an understanding of the clinical significance of these anomalies are essential for making the correct diagnosis and planning patient treatment.

Diagnostic accuracy of serum B-type natriuretic peptide for myocardial ischemia detection during exercise testing with Spect perfusion imaging

OBJECTIVE

To determine whether serum B-type natriuretic peptide measured at rest and peak exercise and DeltaBNP contribute to the predictive value and diagnostic accuracy of exercise test in the diagnosis of myocardial ischemia.

BACKGROUND

Ventricular myocytes release BNP in response to increased wall stress that occurs in acute ischemia. During exercise testing, transient myocardial ischemia could also cause acute myocardial stress and changes in circulating BNP.

METHODS

BNP was measured before and immediately after exercise testing with radionuclide imaging in 203 consecutive subjects referred for chest pain evaluation. Tested subjects were classified as ischemic and non-ischemic based on exercise results, and no ischemia, mild-moderate, and severe ischemia according to perfusion scan results. A logistic regression model, constructed of an ROC and an AUC (area under the curve), was used.

RESULTS

Ischemic ECG changes (> or =1 mm, horizontal S-T shift) were detected in the treadmill exercise test in 127 subjects (62.6%), and 76 (37.4%) had neither ST segment shift nor chest pain. Baseline BNP was higher in the ischemic group compared to the non-ischemic group (p=0.044); peak BNP was also higher in the ischemic group (p=0.025), as was DeltaBNP (p=0.0126). Of these 127 subjects, 106 (52% of all) had abnormal perfusion scan results. In the ischemic group, the median baseline, peak exercise BNP, and DeltaBNP values from baseline to peak were higher than in the non-ischemic group. In the severe ischemic group these variables were approximately three-fold higher than in the mild-moderate ischemic group (p<0.0001 for baseline; p<0.0001 for peak; and p<0.0001 for DeltaBNP). Rest, peak exercise, and DeltaBNP values were significantly higher in patients with previous myocardial infarction (p<0.001) and in patients treated with beta blockers; peak exercise BNP was higher in hypertensives and diabetics (p<0.05). The ROC convergence model showed that the AUC for peak-exercise BNP was best able to discriminate and predict severe ischemia and no ischemia, while DeltaBNP from rest to peak exercise discriminated best between mild-moderate and severe ischemia.

CONCLUSIONS

Peak exercise BNP and DeltaBNP improved the sensitivity, specificity, positive likelihood ratio, predictive value, and diagnostic accuracy of severe ischemia detection during an exercise test. The contribution of BNP determination during exercise was, however, less impressive than previously reported by others.

Coronary-pulmonary artery fistula diagnosed by multidetector computed tomography

Coronary-pulmonary artery fistula is an uncommon cardiac anomaly, usually congenital. Most coronary-pulmonary artery fistulas are clinically and haemodynamically insignificant and are usually found incidentally. This report describes a case of complex coronary-pulmonary artery fistula with two feeding vessels of separate origins: one from the proximal part of the left anterior descending artery and another arising from the right aortic cusp. The complex anatomy of the fistula was shown in detail by multidetector computed tomography using multiplanar reconstruction and 3D volume rendering techniques.

Induction of apoptosis by ultrasound application in human malignant lymphoid cells: role of mitochondria-caspase pathway activation

In the present study, we have focused on the specific question of whether ultrasound application (ULS) delivered with optimized parameters for cavitation generation can stimulate apoptosis in lymphoid cell lines. Suspended T and B lymphoid cell lines (Jurkat and Raji, respectively) were exposed to low frequency ULS (750 KHz) at an intensity level of 54.6 W/cm(2) spatial peak temporal average (SPTA) at focal area, which was found to be the optimal physical parameter to induce apoptosis in these malignant cell lines. Unsonicated cells and cells exposed to gamma-radiation (20 Gy) using (137)Cs source were used as control. Apoptosis was evaluated by cell morphology changes, cell-cycle analysis, and phosphatidylserine exposure. Fraction of cells with low mitochondria membrane potential was observed 1 h after sonication, accompanied by cytochrome c release from mitochondria to the cytosol and caspase-3 activation. Here we present evidence that ULS exposure with cavitation formation on malignant lymphoid cell lines differs from gamma-radiation and is associated with time-dependent apoptosis, which is mitochondria-caspase dependent.

Catheter-delivered ultrasound therapy for native coronary arterial thrombosis and occluded saphenous vein grafts

Acute coronary thrombosis, overlying ruptured atherosclerotic plaque, is the hallmark of myocardial infarction and unstable angina. Despite use of modern therapeutic modalities, including glycoprotein IIb/IIIa antagonists and stenting, intracoronary thrombus heralds an increased risk of serious complications following percutaneous coronary interventions (PCI). Abundant in vitro and in vivo experimental data have proven that ultrasound energy is capable of lysing intravascular thrombus without injuring the vessel wall. Expanding experience and technological advancements now allow us to use this tool in clinical practice. In this article we review the emergence of percutaneous ultrasonic thrombolysis as a safe and effective tool for treatment of patients in various clinical settings associated with coronary thrombosis.

Ultrasound thrombolysis in stent thrombosis

Recent refinement in stent implantation technique and peri-procedural pharmacological treatment has lowered the incidence of stent thrombosis significantly. Still, all stent thromboses are associated with major adverse events. In previous studies it has been suggested that intravascular ultrasound fibrinolysis is safe and effective. In this report, ultrasound successfully reperfused thrombotically occluded stents. These observations suggest that ultrasound may dissolve occlusive platelet-rich thrombus effectively and safely. Cathet. Cardiovasc. Intervent. 51:332-334, 2000.

Catheter-based ultrasound thrombolysis--a new promising thrombus-debulking device for the treatment of intracoronary thrombosis

Angiographic suggestion of intercoronary thrombus is often seen in patients sustaining acute coronary syndromes (ACS). Even in the era of stenting and glycoprotein IIb/IIIa antagonists, the presence of thrombus-rich lesion during percutaneous coronary interventions portends an increased risk of adverse events. It has been hypothesized that reduction of clot-burden prior to PCI may reduce complications and enhance efficacy. Experimental and clinical data have shown that catheter-based ultrasound thrombolysis is capable of inducing an efficacious and safe thrombus-debulking. This article reviews the collective experience with this promising device solution for the treatment of thrombotic lesions in the setting of ACS.

Treatment of lesions with thrombus: beyond stents and GP IIb/IIIa inhibitors

In the presence of an intracoronary thrombus, percutaneous coronary intervention (PCI) will frequently lead to complications. Glycoprotein IIb/IIIa blockade as adjunct to PCI is very effective in patients with non-occlusive clots and biochemical evidence of platelet micro-embolization. Thrombotically-occluded vessels still remain a major clinical problem. This provides a rationale for thrombus debulking prior to PCI. A powerful antiplatelet agent used in combination with a thrombus debulking strategy and stenting of the underlying ruptured plaque offers the potential for further enhancement of PCI. Protection against embolization could potentially be optimized with the use of anti-embolization devices and covered stents.

Ultrasound imaging-guided noninvasive ultrasound thrombolysis: preclinical results

BACKGROUND

Catheter-based therapeutic ultrasound thrombolysis was recently shown to be effective and safe. The purpose of this work was to study the safety and efficacy of external high-intensity focused ultrasound thrombolysis guided by ultrasound imaging in experimental settings.

METHODS AND RESULTS

A therapeutic transducer was constructed from an acoustic lens and integrated with an ultrasound imaging transducer. In vitro clots were inserted into bovine arterial segments and sonicated under real-time ultrasound imaging guidance in a water tank. With pulsed-wave (PW) ultrasound, the total sonication time correlated with thrombolysis efficiency (r(2)=0.7666). A thrombolysis efficiency of 91% was achieved with optimal PW parameters (1:25 duty cycle, 200-micros pulse length) at an intensity (I(spta)) of >35+/-5 W/cm(2). Ultrasound imaging during sonication showed the cavitation field as a spherical cloud of echo-dense material. Within <2 minutes, the vessel lumen evidenced neither residual clot nor damage to the arterial wall. On serial filtration, 93+/-1% of the lysed clot became subcapillary in size (<8 microm). In vitro safety studies, however, showed arterial damage when an I(spta) of 45 W/cm(2) was used for periods of >/=300 seconds.

CONCLUSIONS

External high-intensity focused ultrasound thrombolysis using optimal PW parameters for periods of </=300 seconds appears to be a safe and effective method to induce thrombolysis. The procedure can be guided by ultrasound imaging, thereby allowing the monitoring of therapy.

Apoptosis induction of human myeloid leukemic cells by ultrasound exposure

Therapeutic ultrasound (ULS) and the resulting cavitation process has been shown to induce irreversible cell damage. In this study, we wanted to further investigate the mechanism of ULS-induced cell death and to determine whether apoptosis is involved. High intensity focused pulsed ULS sonication at a frequency of 750 KHz was delivered to HL-60, K562, U937, and M1/2 leukemia cell line cultures. ULS exposure used with induction of transient cavitation in the focal area was delivered with an intensity level of 103.7 W/cm2 and 54.6 W/cm2 spatial-peak temporal-average intensity. As a control, ULS of lower intensity was delivered at 22.4 W/cm2 spatial-peak temporal-average intensity, presumably without generation of cavitation. Our results indicated that DNA damage induced by ULS cavitation did not involve generation of free radicals in the culture media. Morphological alterations observed in cells after exposure to ULS included: cell shrinkage, membrane blebbing, chromatin condensation, nuclear fragmentation, and apoptotic body formation. Apoptotic cells were evaluated by fluorescence microscopy and detected using the terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay, which identifies DNA breaks, and by the leakage of phosphatidylserine from the inner to the outer side of the membrane layer of treated cells. Some bioeffects induced on sonicated HL-60 cells, such as inhibition of cell proliferation, DNA repair, and cell-dependent apoptosis, were found to be similar to those produced by gamma-irradiation. Thus, much of the cell damage induced by therapeutic ULS in leukemia cells surviving ULS exposure appears to occur through an apoptotic mechanism.

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.

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.

Ultrasound inhibits the adhesion and migration of smooth muscle cells in vitro

This study investigated in vitro the effect of therapeutic ultrasound (ULS) on smooth muscle cell (SMC) function as adhesion, migration and proliferation. Experiments were conducted on aortic SMC in culture. The LD50 was established (1.5 W for 15 s at a frequency of 20 kHz) and used as standard dose in all experiments. Control SMC and viable sonicated SMC were compared in each experiment. Migratory capacity decreased 2.4-fold after sonication and stayed reduced for up to 24 h. Adhesion capacity decreased 5.5-fold after ULS. The proliferative capacity was similar to that of nonsonicated SMC. Sonication was accompanied by the disorganization of alpha-SM actin fibers and diminished distribution of vinculin; tyrosinated alpha tubulin and vimentin appeared unaffected. These changes might be responsible for the observed inhibition of SMC adhesion and migration. Sonicated cells exhibited less lamellipodia, membrane collapse and bleb formation. The signal transduction cascade, which involves activation of the phospholipase-C pathway, was unaffected by ULS.

[Ultrasound coronary angioplasty: state of the art and new clinical aspects]

Therapeutic ultrasound was shown to ablate thrombi and to disrupt atherosclerotic plaques in vitro and recently to recanalize occluded coronary arteries in acute myocardial infarction (AMI). The goal of this article is to update collective experience and to weigh the promising and unresolved aspects of this newly developed technology and its clinical results. As therapeutic ultrasound was for long known a synonym for lithotripsy of calculi diseases, it lastly received high attention as a catheter-based ultrasound method to ablate thrombi and disrupt atherosclerotic plaques in interventional cardiology (Figure 1). The effect of therapeutic ultrasound to ablate selectively pathological tissue depends on its bioselectivity for elastic fibers: After ultrasound sonication, healthy tissue-rich in elastin and collagen-including arterial wall remains intact whereas thrombus and plaque with their minimal elastic support are found to be highly susceptible to ablation. Our catheter for coronary ultrasound thrombolysis (Figure 2) consists of a solid metal probe and is connected to a piezo-electric transducer at its proximal end. The distal part ends in a three-wire flexible segment with a 1.6 mm tip ball to guarantee maximal wire flexibility and optimal transmission of ultrasound energy. The initial in vitro studies resulted in a fundamental understanding of the destructive effect of ultrasound on tissue based on 4 factors: mechanical vibration, thermal effects, microcurrents, and cavitation. The first studies on human peripheral vessels were published in 1991 being performed during femoral bypass surgery on occluded and partially obstructed arteries. The procedure was performed without perforation, no adverse side effects emerged, restenosis rate was 20%. The clinical application of coronary ultrasound angioplasty was initiated in 1991; Siegel published his data on 44 patients. In his study, 30 patients with chronic atherosclerotic occlusive lesions and 14 with unstable or stable angina or AMI were treated by ultrasound angioplasty. Residual stenosis after ultrasound treatment was 71%, after balloon dilation reduced to 34%. In the 6-month follow-up angiograms showed no major adverse effect or restenosis. Our experience with coronary ultrasound thrombolysis (CUT) is based on the analysis of 33 patients' data in the feasibility (Table 1) plus multicenter phase of the ACUTE trial (Analysis of Coronary Ultrasound Thrombolysis Endpoints) (Figure 3). Our patients were exclusively treated for AMI by ultrasound angioplasty and afterwards by PTCA if required (Figure 4). The average final percent stenosis was 20% (Figure 5). The main efficacy parameters, device success and angiographic success rates were 100%, clinical success rate was 91.7% (Figure 6 and Table 2). The adverse clinical events of CUT are limited--at least in our studies--to reocclusion of infarct-related artery and ischemia and could be reversed by additional PTCA. No adverse clinical side effects were observed during sonication of the coronary tree. Final angiography revealed residual stenosis of 20% without morphological signs. These excellent results suggest that bioselectivity of ultrasound together with the developed skills of the catheter system induces rapid and selective thrombolysis with no need to cross the target lesion before sonication. But what is the better solution for thrombosis and which for plaque disruption? The development of transluminal balloon catheter really modified therapeutic approach to obstructive coronary and peripheral arterial disease but it is still accompanied by a high rate of abrupt closure, AMI and death. Although the use of intravenous thrombolytic agents is well established in the treatment of AMI and these agents are widely used, a large patient collective remains (up to 33% and more) in whom their use is inadvisable due to recent stroke, surgery, trauma or other contraindications. (ABSTRACT TRUNCATED)

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.

Significance of a coronary artery with thrombolysis in myocardial infarction grade 2 flow "patency" (outcome in the thrombolysis and angioplasty in myocardial infarction trials). Thrombolysis and Angioplasty in Myocardial Infarction Study Group

To determine whether pharmacologic reperfusion to Thrombolysis in Myocardial Infarction (TIMI) grade 2 flow during acute myocardial infarction confers the same clinical benefit as restoration of TIMI 3 flow, in-hospital clinical and angiographic outcomes in 1,229 patients prospectively enrolled in the Thrombolysis and Angioplasty in Myocardial Infarction trials were analyzed. Patients were treated with intravenous tissue plasminogen activator or urokinase, or both. Angiography of the infarct-related artery 90 minutes after initiation of thrombolytic therapy demonstrated TIMI grades 0, 1, 2, or 3 flow in 20%, 7%, 17%, and 55% of vessels, respectively. Rescue or adjunctive coronary angioplasty was performed in 80%, 27%, and 16% of patients with TIMI 0/1, 2, or 3 flow, respectively. Predischarge angiography was performed in 963 patients. A significant gradient of increasing mortality was seen in patients with lower TIMI flow (4.3%, 6.1%, and 10.1% with TIMI 3, 2, and 0/1 flow, respectively, p = 0.002). The incidence of congestive heart failure and recurrent ischemia was significantly higher in patients with TIMI 2 than with TIMI 3 perfusion (26% vs 19% for heart failure, p = 0.03; 23% vs 17% for recurrent ischemia, p = 0.05). Acute left ventricular ejection fraction and infarct zone regional wall motion were also significantly improved in patients with TIMI 3 than with TIMI 2 flow, with trends toward better improvement in global and regional function in the TIMI 3 group. These findings were not affected by the use of acute coronary angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

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.

Percutaneous transluminal coronary angioplasty in elderly patients

Fifty-six patients aged 75 years and older underwent percutaneous transluminal coronary angioplasty (PTCA) at our institution from 1984 to 1991. The average age was 76.7 +/- 1.5 years, and 84% of the patients were males. Single-vessel disease occurred in 21 patients, double-vessel disease in 16, and three-vessel disease in 19 patients. The mean left ventricular ejection fraction was 57 +/- 5%, and 8 patients had an ejection fraction of < 40%. The anginal functional class was I in 1 patient, II in 3, III in 6, and IV in 46 patients. Single-vessel PTCA was attempted in 43 patients, two-vessel PTCA in 8, and three-vessel PTCA in 5 patients. Revascularization was complete in 35% of the patients, incomplete in 57, and no revascularization was obtained in 8% of the patients. Ninety-one percent of the patients had a successful procedure. In 5 patients there was severe dissection, 1 patient died, 1 patient had an acute myocardial infarction, and 1 patient had emergency bypass surgery. Long-term follow-up (6-96 months, mean 21 +/- 4) in the 51 successfully treated patients revealed late cardiac death in 1 patient, repeated PTCA for restenosis in 9, and coronary bypass surgery in 2 patients. Twenty-two patients were asymptomatic, 12 had improved symptoms, and 5 remained symptomatic. PTCA appears to be a safe and effective treatment in elderly patients with one- and two-vessel disease, with excellent long-term results. Age is not a contraindication to PTCA. The results in elderly patients with three-vessel disease are less encouraging.

Heparin monitoring during coronary intervention: activated clotting time versus activated partial thromboplastin time

Activated clotting time (ACT) and activated partial thromboplastin time (APTT) are used for monitoring heparin therapy during coronary angioplasty. The purpose of this study was to determine which parameter is more useful clinically, and to assess the correlation between ACT and APTT. The authors measured these parameters at fixed intervals (0, 15, 30, 60, 150 and 240 mins) following intravenous heparin administration (12,500 +/- 3100 U) during coronary intervention in 39 patients. APTT rose to 'therapeutic' levels (true therapeutic levels have not been defined for these coagulation tests) more rapidly and fell to subtherapeutic levels more slowly than did ACT. The combination of a subtherapeutic ACT with a therapeutic APTT occurred far more often than did concordant therapeutic ACT and APTT values (69% versus 31%, P < 0.0004). There was a relatively poor correlation between ACT and APTT (r = 0.76). There were no abrupt closures in the study patients. It was concluded that subthreshold ACTs with high APTTs occur frequently, suggesting the improved suitability of ACT for intraprocedural monitoring of anticoagulation status. If one accepts the minimum amount of anticoagulation for prevention of thrombosis to be that which produces an ACT of greater than 300 s, then an APTT of greater than 90 s does not predict adequate anticoagulation.

Thrombosis of a flexible coil coronary stent: frequency, predictors and clinical outcome

OBJECTIVES

The aim of this study was to evaluate the predictors and clinical sequelae of stent thrombosis.

BACKGROUND

Although coronary artery stenting is being increasingly applied, the major unique complication of stent thrombosis is not well characterized.

METHODS

We studied 145 patients who underwent coronary artery stenting with the Gianturco-Roubin flexible coil design for abrupt vessel closure or to prevent restenosis. There were 17 stented vessel closures (11.7%), 7 as a result of acute (< 24 h) and 10 of subacute (days 1 to 21) thrombosis.

RESULTS

In seven patients successful coronary recanalization was achieved with thrombolytic agents and balloon angioplasty. Creatine kinase was significantly elevated in 13 patients, with a Q wave myocardial infarction in 11 and emergency coronary artery bypass grafting in 8. Comparisons (multivariate analysis) with a control cohort (n = 33) of patients without thrombosis matched for age, gender and vessel stented revealed lesion eccentricity (p = 0.003), unstable angina (p = 0.048) and indication for stent implantation (abrupt closure versus restenosis) (p = 0.002), as predictors of thrombotic occlusion of stented vessels. Subtherapeutic anticoagulation (activated partial thromboplastin time < 2 times control value, prothrombin time < 1.4 control value) occurred at least once during the hospital stay in all 10 patients with subacute thrombosis and in 20 of 33 control patients (p = 0.047). In 2 patients with subacute thrombosis and 11 control subjects, subtherapeutic anticoagulation was necessitated by bleeding.

CONCLUSIONS

Early thrombosis after coronary stenting was relatively common (> 10%), occurring predominantly in eccentric lesions and in patients with unstable angina pectoris. This complication is associated with significant adverse clinical outcomes and may be reduced by more intensive anticoagulation yet, in a delicate balance, can be precipitated by inadequate heparin therapy.

Ultrasonic thrombus ablation: in vitro assessment of a novel device for intracoronary use

An ultrasonic thrombolysis device designed for intracoronary use was developed and evaluated in vitro to assess efficacy in achieving clot ablation without deleterious effects, such as heat generation and production of large particles during clot ablation. Studies on 31 samples with a bench-top version demonstrated that clot ablation was rapid (typically 2 mL in under 2 minutes) and no macroscopic particles were released. The fluid produced did not reclot. Studies with a clinical version of the device that can be passed through a 10 Fr PTCA guiding catheter confirmed that clot ablation was rapidly achieved. Little particulate material was produced and the maximum temperature achieved did not exceed 52 degrees C. The device functions well in vitro, releasing little particulate material and causing limited local heating. It seems suitable for intracoronary use and will undergo further in vivo testing.

Shock-wave thrombus ablation, a new method for noninvasive mechanical thrombolysis

Successful experimental and clinical experience with thrombus ablation has been attained with high-power acoustic energy delivered in a catheter. The goal of this study was to investigate the feasibility of noninvasive thrombus ablation by focused high-power acoustic energy. The source for high-power acoustic energy was a shock-wave generator in a water tank equipped with an acoustic lens with a fixed focal point at 22.5 cm. Thrombus was prepared in vitro, weighed (0.24 +/- 0.08 g), and inserted in excised human femoral artery segments. The arterial segments wer ligated, positioned at the focal point and then randomized into either test (n = 8) or control (n = 7). An x-ray system verified the 3-dimensional positioning of the arterial segment at the focal point. A 5 MHz ultrasound imaging system continuously visualized the arterial segment at the focal point before, during and after each experiment. The test segments were exposed to shock waves (1,000 shocks/24 kv). The arterial segment content was then flushed and the residual thrombus weighed. The arterial segment and thrombus were fixed and submitted to histologic examination. The test group achieved a significant ablation of thrombus mass (0.25 +/- 0.15 vs 0.07 +/- 0.003 g; p = 0.0001) after application of shock waves. Arterial segments showed no gross or microscopic damage. Ultrasound imaging revealed a localized (1.9 +/- 0.5 cm2), transient (744 +/- 733 ms), cavitation field at the focal point at the time of application of focused shock waves. Thus, focused high-power acoustic energy can effect noninvasive thrombus ablation without apparent damage to the arterial wall.(ABSTRACT TRUNCATED AT 250 WORDS)

Preprocedure warfarinization and brachial approach for elective coronary stent placement--a possible strategy to decrease cost and duration of hospitalization

Intracoronary stenting, while potentially beneficial to treat abrupt closure and to prevent restenosis after angioplasty, requires intermediate-term warfarinization to prevent stent thrombosis. Hospitalization is often prolonged because of the need to establish anticoagulation. Hospital charges have been reported to be considerably higher with stenting than with balloon angioplasty alone, although the long-term cost ramifications remain uncertain due to the fact that stenting may limit restenosis. We describe a technique wherein stent placement is performed while the patient is already partially anticoagulated, which may decrease costs associated with stenting.

Streptokinase immunogenicity in thrombolytic therapy for acute myocardial infarction

The major drawback in implementing thrombolytic therapy with streptokinase in cases of acute myocardial infarction (AMI) stems from its antigenicity. To evaluate the dimensions of this problem, the immune response following thrombolytic therapy with streptokinase was prospectively studied in 16 patients with AMI. Streptokinase was given to 12 patients once and to 4 patients twice within 4-14 days. No clinical immune responses were observed following treatment. The specific antistreptokinase immune responses subsequent to streptokinase administration were monitored. The cellular immune response, reflected by the 3H-thymidine uptake of streptokinase-stimulated peripheral blood mononuclear cells, was three times higher than that of the controls. The antistreptokinase circulating IgG antibody level, measured by an enzyme-linked immunosorbent assay, was 8 times higher than that of the controls. No antistreptokinase circulating IgE antibodies could be detected and no decrease in complement concentration was noted. The profile and magnitude of the immune response of patients who had received two treatments were similar to those of patients who had received a single treatment only. Our data suggest that thrombolytic therapy with streptokinase in AMI elicits a characteristic profile of antistreptokinase immune responses, in vitro, not necessarily associated with parallel clinical immune responses. An early repeat treatment with streptokinase was not accompanied by clinical or exacerbated in vitro immune responses.

Ultrasonic angioplasty in totally occluded peripheral arteries. Initial clinical, histological, and angiographic results

BACKGROUND

Ultrasonic angioplasty was recently shown to ablate thrombi and atherosclerotic plaques in vitro and to recanalize occluded arteries in experimental animal models. The goal of the present study was to examine the clinical feasibility of ultrasonic angioplasty.

METHODS AND RESULTS

Intraoperative ultrasonic angioplasty was performed in vivo on totally occluded peripheral arteries (n = 7). The ultrasonic angioplasty device consists of a 1.6-mm diameter flexible wire attached to a piezoelectric crystal generating ultrasound at 20 kHz. The controls, totally occluded human atherosclerotic femoral arterial segments (n = 6), were crossed mechanically with the ultrasound wire ex vivo but without application of ultrasonic energy. Ultrasonic angioplasty achieved successful recanalization without perforation in all vessels. Angiograms of the treated arteries showed an average lumen patency of 82.5%. Histological examination of the recanalized arteries revealed that the recanalization had taken place through intima diffusely involved with complicated plaque. The treated arteries, compared with the controls, had greater area of recanalized lumen (5.9 +/- 1.8 versus 1.7 +/- 0.4 mm2, p less than 0.05) and more flow (49.3 +/- 16.0 versus 11.8 +/- 4.9 ml/min, p less than 0.03). The damage in treated and control arteries was similar. Size-distribution analysis of the plaque debris from the treated arteries showed that 41 +/- 5% of the debris was 0.2-8 microns, 48 +/- 8% was 8-30 microns, and the remainder was 30-100 microns. In the mechanically crossed arteries, there was a shift in the distribution to larger size debris with 47 +/- 1% greater than 100 microns (p less than 0.001).

CONCLUSIONS

Ultrasonic angioplasty may be a useful clinical method for recanalization of total occlusions in patients with peripheral vascular disease. Ultrasonic energy appears to cause controlled injury to the atherosclerotic intima by selectively disrupting the ultrasound-sensitive occlusion.

Experimental ultrasonic angioplasty: disruption of atherosclerotic plaques and thrombi in vitro and arterial recanalization in vivo

To investigate the use of high energy ultrasound as an alternative energy for angioplasty, an experimental ultrasonic angioplasty device was developed. The device was studied in two bioassay systems: an in vitro system for the disruption of atherosclerotic plaques and thrombi and an in vivo system for the recanalization of occluded canine femoral arteries. In vitro, sonication efficiently reduced the size of the plaques. Atheromatous plaques (n = 11) disrupted at a rate of 21 +/- 8 s/cm2; complicated plaques (n = 14) disrupted at a rate of 132 +/- 45 s/cm2 (p less than 0.001). Histologic examination revealed that the disruption of the plaques took place without concurrent damage to the media or adventitia. Ninety percent of the disrupted plaque debris had a diameter of less than 20 microns and was composed primarily of cholesterol monohydrate crystals. Solid thrombus (n = 5) weight was reduced from 1.6 +/- 0.2 to 0.4 +/- 0.1 g (p less than 0.0001) after 20 s of sonication. In vivo, sonication resulted in recanalization in all seven arteries tested in seven dogs. The obstruction was reduced from 93 +/- 11% to 18 +/- 7% (p less than 0.001). On histologic examination, the arterial wall injury index was found to be 1.56 +/- 0.42 in the test arteries compared with 1.37 +/- 0.47 in the control arteries (p = NS). The disruption of atherosclerotic plaques and thrombi, together with the efficient recanalization of the occluded arteries, demonstrates the potential of ultrasound angioplasty as a catheter-based technique for angioplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

The mechanism of the obstruction in calcific aortic stenosis with bicuspid valve: a reason for failure of balloon aortic valvuloplasty in the elderly

Percutaneous aortic balloon valvuloplasty failed to relieve the obstruction in 2 elderly patients with calcific aortic stenosis. Intraoperative and pathologic examination showed bicuspid aortic valve with symmetric cusps, straight and fibrotic cusp edges and fractured calcific nodules of the aortic valve. Failure of balloon valvuloplasty in these patients, in spite of successful fractures of calcific nodules, was due to inability to influence the spring-like action of the thickened edges of the valve which represents a specific additional cause of obstruction in calcific bicuspid aortic valve of the elderly.

Human muscle-derived, tissue specific, myocytotoxic T cell lines in dermatomyositis

Mononuclear cells were isolated from the inflamed muscle tissue of a patient suffering from dermatomyositis (DM). These were expanded in long-term culture and maintained in the presence of IL-2 containing culture medium. Two cell lines were established, one of the helper/inducer (OKT4+) and the other of the suppressor/cytotoxic phenotype (OKT8+). The OKT4+ cell line exhibited a non HLA-restricted, tissue-specific, myocytotoxic effect on rat muscle cell culture. Its lymphoproliferative response to human muscle antigen was HLA-restricted. The OKT8+ cell line exhibited a non HLA-restricted, tissue-specific response to muscle antigens and no myocytotoxic activity in in vitro rat muscle cell culture. It is likely that clones of OKT4+ lymphocytes in patients suffering from DM are associated with the pathogenesis of the disease--they probably mediate the diffuse damage to skeletal muscle through their myocytotoxic activity.