Non-contrast computed tomography is comparable to contrast-enhanced computed tomography for aortic volume analysis after endovascular abdominal aortic aneurysm repair.

OBJECTIVES: To evaluate whether non-contrast computed tomography (NCCT) images are as reliable as contrast-enhanced computed tomography (CECT) images for the measurement of aortic volume (AV). MATERIALS AND METHODS: A total of 316 pairs of AVs were retrospectively measured from 316 consecutive patients, who underwent endovascular aneurysm repair (EVAR). A standardised multidetector computed tomography protocol was used to obtain precontrast, arterial and delay-phase images. A single blinded, experienced observer measured the AV from the lowest renal artery to the aortic bifurcation by means of the disc-summation method, using the precontrast and arterial-phase images. A second blinded observer measured the AV again in 16 randomly chosen cases. RESULTS: Both NCCT and CECT yielded similar AVs that were highly correlated (r(2) = 0.99; P < 0.0001). Bland and Altman analysis revealed a small bias (mean ± 2 standard deviations: -0.9 ± 8 ml). The intraclass correlation coefficients (all >0.99; P < 0.0001) and low repeatability coefficients indicated that the AVs were reproducible with both methods. CONCLUSIONS: The AVs measured from NCCT images were accurate and highly reproducible compared with those from CECT images. Therefore, NCCT can be a reasonable alternative to CECT for AV assessment after EVAR. This is particularly important for patients with renal insufficiency (potentially sparing them from nephrotoxic contrast agents and unnecessary radiation) or allergy to contrast agents.

The role of leading centers for endovascular surgery in education and training for endovascular treatment of peripheral vascular disease.

The field of peripheral vascular disease (PVD) management is rapidly evolving with the advent of new endovascular techniques. These new techniques frequently involve hybrid approaches for treating complex aortic pathologies. Like many new procedures, endovascular techniques present new challenges for physicians who care for patients with complex vascular pathologies. Physicians must not only understand the disease entity, but the knowledge, expertise in and all available therapeutic options, including the new techniques being employed. To enable physicians to meet these requirements for endovascular techniques and stent-graft technology and to become credentialed to perform them, specific training requirements must be established for peripheral vascular training programs. This is a literature-based review discussing the development of interventional vascular training programs and the incorporation of catheter-based endovascular techniques.

Totally percutaneous aortic aneurysm repair: methods and outcomes using the fully integrated IntuiTrak endovascular system.

AIM: A totally percutaneous approach to endovascular abdominal aortic aneurysm repair (PEVAR) has been shown in multiple reports to be feasible, but carries attendant risks that appear to increase with increasing sheath size. We report our methods and sequential PEVAR case experience using a new delivery system having an integrated 19Fr introducer sheath for treatment of patients with aortic necks up to 32 mm in diameter. METHODS: A single institution, prospective, controlled evaluation was conducted in 57 consecutive patients with abdominal aortic aneurysm who underwent PEVAR between December 2008 and April 2010. All patients have been followed for at least 30 days. RESULTS: Patients presented at a mean age of 74 years with median AAA diameter of 5.4 cm preprocedurally. Calcified/tortuous access vessels were identified in 98% of patients. All PEVAR procedures with adjunctive "pre-close" use of the Prostar XL closure device were performed in a hybrid endovascular suite with patients maintained under conscious sedation and local anesthesia. The anatomically-fixed bifurcated stent graft and aortic/limb extensions as needed were implanted via the 19 Fr indwelling introducer sheath with minimal blood loss (79 mL). Technical success was 98%, with one conversion to open repair attributable to very small diameter (4 mm) access vessels. Cumulatively, major access-related complications were observed in five patients (8.8%) within 30 days. CONCLUSION: PEVAR using the IntuiTrak System with 19Fr introducer sheath with vessel closure facilitated by the Prostar XL device is feasible, even in patients with challenging access anatomy. Further evaluation in a prospective, multicenter, randomized trial is warranted.

Catheter aspiration thrombectomy during carotid stenting is safe and potentially efficacious: a pilot retrospective study.

AIM: Despite distal embolic protection (DEP) during carotid artery stenting (CAS), there is still an appreciable risk of stroke, especially in symptomatic patients and octogenerians. The mechanism of embolic events is possibly related to microembolization of debris remaining on or forming on stent struts. We evaluated the safety of using aspiration thrombectomy after CAS. METHODS: Between August 2006 and July 2010, 80 symptomatic and asymptomatic patients with severe carotid artery stenosis (>80%) underwent CAS utilizing DEP. After completion of CAS and before removal of DEP, an aspiration catheter was passed through the CAS segment. Both extracted volume and the DEP were visually examined. The primary endpoint was stroke and death at 30 days. These patients were divided into two groups, Group 1 (N=7) comprised those who had aspiration thrombectomy to treat no-flow or an acute neurologic change that occurred during CAS. Group 2 (N=73) comprised patients that underwent prophylactic aspiration thrombectomy. Outcomes were then compared to a control group (N=925) who had CAS with DEP, but without aspiration thrombectomy. RESULTS: Moderate to large amounts of debris were extracted from the CAS segment in the majority of thrombectomy patients (90%). There was one death (1%) and one stroke (1%) in the thrombectomy groups, while the control group had 3.0% rate of death and stroke (P=0.83). CONCLUSION: Aspiration thrombectomy recovers large to moderate amounts of debris and is safe and does not increase adverse periprocedural events. A large scale, randomized trial with magnetic resonance imaging (MRI) is needed to further investigate our findings.

Septal myomectomy and mitral valve replacement for idiopathic hypertrophic subaortic stenosis: short- and long-term follow-up.

The long-term results of septal myotomy-myomectomy or mitral valve replacement, or both, were assessed in 36 patients with idiopathic hypertrophic subaortic stenosis who were followed up for 5 to 67 months (mean 48) postoperatively. The mean left ventricular outflow tract gradient at rest decreased postoperatively in all three patient groups. It decreased from 60 mm Hg (range 17 to 160) preoperatively to 3 mm Hg (range 0 to 20) postoperatively (p less than 0.001) in the 13 patients who underwent mitral valve replacement alone, from 69 mm Hg (range 18 to 140) to 35 mm Hg (range 20 to 50) (p less than 0.05) in the 12 patients who underwent myotomy-myomectomy alone and from 89 mm Hg (range 60 to 165) to 3.8 mm Hg (range 0 to 27) (p less than 0.001) in the 11 patients who underwent myomectomy plus mitral valve replacement. The reduction in gradient was more impressive after mitral valve replacement with or without septal myotomy-myomectomy than after septal myotomy-myomectomy alone. There was a marked reduction in symptoms after all three surgical procedures that was long-lasting and independent of the type of operation performed. There was no operative mortality. Postoperative annual mortality rate was 1.6%. Patients with severe congestive heart failure, significantly elevated left ventricular end-diastolic pressure and atrial fibrillation have a less favorable long-term postoperative prognosis. Septal myotomy-myomectomy is recommended as the procedure of choice for the majority of patients with idiopathic hypertrophic subaortic stenosis who require surgery, because it can alleviate symptoms without subjecting patients to the complications of a valve prosthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

Preliminary results of endovascular abdominal aortic aneurysm exclusion with the AneuRx stent-graft.

OBJECTIVES: This study evaluated the clinical effectiveness of the Medtronic AneuRx stent-graft in patients with infrarenal abdominal aortic aneurysms (AAAs) who were treated in an endovascular suite. BACKGROUND: The use of endovascular stent-graft prosthesis for the treatment of AAAs is receiving increasing attention as an alternative to standard surgical repair. Endovascular treatment of AAAs offers the potential to avoid the significant morbidity and mortality associated with surgical repair. METHODS: In this series, 215 patients have undergone AAA exclusion with the AneuRx stent-graft. Six-month follow-up is available in 132 patients; one-year follow-up is available in 84 and two-year follow-up in 22. RESULTS: Of the patients, one hundred ninety-two (89%) were male; 87% had hypertension, and 58.6% were American Society of Anesthesiologists grade IV or higher. The procedural success was 99.5%; we were unable to place the device in one patient. There was no procedural or one-month mortality. There were no acute conversions to surgical repair. One patient had a non-Q-wave myocardial infarction 24 h after the procedure. Endoleaks were present in 82 patients (42%) at discharge, 15 patients (11.3%) at six months and 10 patients (11.9%) at one year. Twenty-two patients had a secondary procedure for endoleak repair of which three were conversions to surgical repair. Twelve late deaths have occurred, none due to device failure or AAA rupture. Mean hospital stay was 1.9 days. CONCLUSIONS: These results reveal that infrarenal AAAs can be safely and successfully treated in an endovascular suite with the AneuRx stent-graft. Further follow-up is needed to determine the long-term efficacy of endoluminal treatment to prevent rupture and death due to AAAs.

Progression of hypertrophic cardiomyopathy into a hypokinetic left ventricle: higher incidence in patients with midventricular obstruction.

The development of segmental or generalized left ventricular hypokinesia is an unusual occurrence in patients with hypertrophic cardiomyopathy. To determine the incidence and possible pathophysiologic mechanisms responsible for this process, the serial clinical and laboratory data of 62 patients with the diagnosis of hypertrophic cardiomyopathy were analyzed. During a mean follow-up period of 8 years (range 2 to 21), 5 patients (Group A) developed left ventricular hypokinesia, whereas the remaining 57 patients (Group B) continued to exhibit the clinical and laboratory findings of hypertrophic cardiomyopathy. Three patients developed a dilated left ventricle with generalized hypokinesia; two other patients had segmental left ventricular wall motion abnormalities. None of these five patients who developed left ventricular hypokinesia had fixed coronary artery disease. The mean age, sex, mean duration of follow-up, presence of coronary myocardial bridges and angina pectoris, and an interventricular gradient were all similar in Groups A and B. Midventricular obliteration was seen in 4 (80%) of the 5 patients in Group A and in 4 (7%) of the 57 patients in Group B (p less than 0.001). Findings from this study reveal that segmental or generalized left ventricular hypokinesia can develop in patients with hypertrophic cardiomyopathy in the absence of fixed coronary artery disease. Such hypokinesia can occur after an acute myocardial infarction or it can develop gradually without clinical or electrocardiographic evidence of infarction. Patients with the mid-ventricular obliteration variant of hypertrophic cardiomyopathy are at a higher risk of developing segmental or diffuse left ventricular hypokinesia.

Percutaneous and surgical interventions for in-stent restenosis: long-term outcomes and effect of diabetes mellitus.

OBJECTIVE: We examined long-term outcomes of patients with in-stent restenosis (ISR) who underwent different percutaneous interventions at the discretion of individual operators: balloon angioplasty (BA), repeat stent or rotational atherectomy (RA). We also examined long-term outcomes of patients with ISR who underwent coronary artery bypass surgery (CABG). BACKGROUND: In-stent restenosis remains a challenging problem, and its optimal management is still unknown. METHODS: Symptomatic patients (n = 510) with ISR were identified using cardiac catheterization laboratory data. Management for ISR included BA (169 patients), repeat stenting (117 patients), RA (107 patients) or CABG (117 patients). Clinical outcome events of interest included death, myocardial infarction, target vessel revascularization (TVR) and a combined end point of these major adverse cardiovascular events (MACE). Mean follow-up was 19+/-12 months (range = 6 to 61 months). RESULTS: Patients with ISR treated with repeat stent had significantly larger average post-procedure minimal lumen diameter compared with BA or RA (3.3+/-0.4 mm vs. 3.0+/-0.4 vs. 2.9+/-0.5, respectively, p < 0.05). Incidence of TVR and MACE were similar in the BA, stent and RA groups (39%, 40%, 33% for TVR and 43%, 40%, 33% for MACE, p = NS). Patients with diabetes who underwent RA had similar outcomes as patients without diabetes, while patients with diabetes who underwent BA or stent had worse outcomes than patients without diabetes. Patients who underwent CABG for ISR, mainly because of the presence of multivessel disease, had significantly better outcomes than any percutaneous treatment (8% for TVR and 23% for MACE). CONCLUSIONS: In this large cohort of patients with ISR and in the subset of patients without diabetes, long-term outcomes were similar in the BA, repeat stent and RA groups. Tissue debulking with RA yielded better results only in diabetic patients. Bypass surgery for patients with multivessel disease and ISR provided the best outcomes.

TriVascular Ovation®: it's role in solving current endograft deficiencies.

Endovascular aneurysm repair (EVAR) techniques and technologies have rapidly advanced over the last two decades. The basic premise of EVAR is to durably exclude flow from the aneurysmal sac without exerting untoward effects on the non-diseased anatomy by using minimally invasive surgical techniques. However, these fundamental components have not yet been perfected with traditional stent grafts and remain important areas for further EVAR refinement. Latest-generation stent grafts are in development to accommodate these therapeutic goals. The Ovation Prime® endograft was specifically developed to address the main limitations of EVAR today by expanding EVAR eligibility, allowing least invasive treatment protocols, and protecting the proximal neck from dilatation over the long term. The purpose of this paper was to detail the primary deficiencies typically encountered with EVAR and to describe how the Ovation Prime® endograft overcomes these limitations.

Safety of outpatient cardiac catheterization.

In this study, we compared the procedure-related complications of inpatient and outpatient cardiac catheterization when performed at the same institution by the same group of cardiologists. The majority of the studies were done using a brachial arterial cutdown approach. The mean age, sex, cardiac diagnosis, mean left ventricular ejection fraction, and the distribution of coronary arterial lesions were similar in both groups. There were relatively more patients in the New York Heart Association's class 4 in the inpatient group (p less than 0.01). In the outpatient group (676 patients), there were no major complications, and the rate of minor complications was 1 percent. In the inpatient group (1,106 patients), the rate of major complications was 0.4 percent and of minor complications 1.4 percent. The rates of major, minor, and total complications were statistically similar between the two groups. In the outpatient group the presence of left main coronary arterial disease, triple-vessel coronary disease, a left ventricular ejection fraction less than 30 percent, or a history of a recent myocardial infarction did not alter rates of complications. The hospital-related cost of the procedure on an outpatient basis was 26 percent less than on an inpatient basis. Our findings indicate that outpatient cardiac catheterization, using a brachial cutdown approach, is safe even in a higher risk subgroup of patients and provides significant financial savings.

Anomalous left coronary artery from pulmonary artery. Unusual case complicated by coronary arterial disease and fistula from coronary artery to left ventricle.

A 42-year-old woman with an anomalous left coronary artery originating from the pulmonary artery and a fistula from the left coronary artery to the left ventricle was treated by aortocoronary bypass grafting of an autologous saphenous vein. The presence of an abundant collateral circulation and of fistulous communications between the left coronary artery and the left ventricle, in our opinion, was the reason that this patient remained asymptomatic until the age of 40 years. We believe that this is the first report of the findings in an adult patient who had these two rare congenital anomalies complicated occlusive coronary arterial disease.

Concomitant subclavian and coronary artery disease.

BACKGROUND: Proximal subclavian artery occlusive disease in the presence of a patent internal mammary artery used as a conduit for a coronary artery bypass graft procedure may cause reversal of internal mammary artery flow (coronary-subclavian steal) and produce myocardial ischemia. METHODS: We reviewed outcome to determine whether subclavian artery revascularization can provide effective protection from and treatment for coronary-subclavian steal. Between 1985 and 1997, 20 patients had either concomitant subclavian and coronary artery disease diagnosed before operation (group 1, 5 patients) or symptomatic coronary-subclavian steal occurring after a previous coronary artery bypass graft procedure (group 2, 15 patients). Patients in group 1 received direct subclavian artery bypass and a simultaneous coronary artery bypass graft procedure in which the ipsilateral internal mammary artery was used for at least one of the bypass conduits. Patients in group 2 received either extrathoracic subclavian-carotid bypass (5 patients, 33.3%) or percutaneous transluminal angioplasty and stenting (10 patients, 66.7%) as treatment for symptomatic coronary-subclavian steal. RESULTS: All patients were symptom-free after intervention. One patient treated with percutaneous transluminal angioplasty and stenting died of progressive renal failure. Follow-up totaled 58.5 patient-years (mean, 3.1 years/patient). In group 1, primary patency was 100% (mean follow-up, 3.7 years). In group 2, one late recurrence was treated by operative revision, yielding a secondary patency rate of 100% (mean follow-up, 2.9 years). CONCLUSIONS: Subclavian artery revascularization can provide effective protection from and treatment for coronary-subclavian steal with acceptably low operative risk. Midterm follow-up demonstrates good patency.

Use of continuous wave Doppler echocardiography to evaluate the hemodynamic importance of atrial systole in patients with mitral stenosis.

Continuous wave Doppler echocardiography was used to assess the hemodynamic role of left atrial systole and its effect on left ventricular performance in 31 patients with isolated mitral stenosis. Fourteen of the patients had mild stenosis, whereas the remaining 17 had severe stenosis. The contribution of atrial systole to the cardiac output was 24% in the patients with mild stenosis and 15% in those with severe stenosis (p less than 0.01). This study reveals the importance of continuous wave Doppler echocardiography in assessing the atrial influence on left ventricular performance in patients with mitral stenosis.

Outcomes following extracranial carotid artery stenting in high-risk patients.

BACKGROUND: Carotid artery angioplasty and stenting has become a viable alternative to carotid endarterectomy (CEA), especially for patients considered at high risk for post-operative complications. This study investigated the feasibility, safety and long-term outcome of carotid artery stenting (CAS) in high-risk patients. METHODS: From July 1995 to November 2000, sixty-two consecutive patients considered to be at high risk for post-operative complications of CEA were followed prospectively after undergoing extracranial CAS procedures. RESULTS: Sixty-two patients [37 men (60%) and 25 women (40%)] underwent a total of 69 CAS procedures. The mean age was 67 +/- 9 years (range, 32-89 years). Comorbid conditions included hypertension in 95% and severe coronary artery disease in 58%. Sixteen patients (26%) had a previous ipsilateral CEA, twenty-one percent had a history of neck radiation and 32% had a history of significant contralateral carotid artery disease. Fifty-two patients (84%) were symptomatic. All 69 CAS procedures were technically successful. The major post-operative complications were two minor strokes (2.8%), one major stroke (1.4%) and one fatal major stroke (1.4%). The mean length of follow-up was 17 months (range, 4 months to 5.6 years). Two patients (2.8%) have suffered ipsilateral neurologic events following CAS. Long-term follow-up revealed restenosis at 6 months in 4 patients (5.7%). CONCLUSIONS: Carotid artery angioplasty and stenting is safe and feasible. This procedure produces satisfactory outcomes in patients who are at high risk for post-operative complications of CEA.

A novel method for endoluminal treatment of abdominal aortic aneurysms. With bare-metal Wallstent endoprostheses and endovascular coils.

The established therapy for symptomatic, expanding abdominal aortic aneurysms is open surgical replacement with an artificial graft. Over the last several years, there has been increasing enthusiasm for the use of endoluminal graft prostheses to exclude abdominal aortic aneurysms. However, even with rapid advances in stent graft technology, certain problems (i.e., large profile of the devices, risk of thromboembolism, poor flexibility, endoleak formation, and side-branch occlusion) have yet to be overcome. We present the case of an 85-year-old woman with multiple comorbid illnesses who underwent endoluminal repair of her expanding abdominal aortic aneurysms. We used bare-metal Wallstent endoprostheses (Schneider, Inc.; Minneapolis, Minn) in combination with endovascular coils (Cook, Inc.; Bloomington, Ind). The bare-metal Wallstent endoprostheses were used because the patient had severely narrowed iliac arteries and a large side branch originating from the aneurysm. The procedure was technically successful, and there was no significant morbidity. Follow-up angiographic evaluation at 6 months revealed no evidence of vascular enlargement; it also revealed preservation of important side branches, and spontaneous thrombosis of the aneurysms.

Comparison of Wallgraft and Wallstent for treatment of complex iliac artery stenosis and occlusion. Preliminary results of a prospective randomized study.

We performed a prospective randomized study to compare the use of a bare metal stent (WALLSTENT Endoprosthesis) with use of a covered stent (WALLGRAFT Endoprosthesis)-both made by Schneider, Inc.; Minneapolis, Minn-for the treatment of complex iliac artery stenosis and occlusion. We report the preliminary results of a study performed at our institution from 1 February 1997 through 31 April 1997. The patient group was composed of 6 women and 4 men, with a mean age of 61.8 years (range, 47 to 73 years). Six WALLGRAFT endoprostheses (4 in the left iliac artery and 2 in the right) and 9 WALLSTENT endoprostheses (5 in the left iliac artery and 4 in the right) were implanted. The mean percent stenosis before treatment was similar in both groups (84.17% in the WALLGRAFT group and 82.14% in the WALLSTENT group). The post-treatment stenosis and peak systolic gradients were negligible or zero in both groups. The devices were safely deployed and technical success (< 30% residual stenosis) was achieved in both groups. The mean thigh-brachial index was similar in the 2 groups, both before treatment (0.65 in the WALLGRAFT group and 0.64 in the WALLSTENT group) and after treatment (1.12 in the WALLGRAFT group and 1.12 in the WALLSTENT group). Evaluation of clinical success revealed that symptoms of intermittent claudication improved markedly in 4 of 5 patients who received the WALLGRAFT Endoprosthesis. In the WALLSTENT group, 1 patient had symptomatic improvement, another had 1 limb improve and the other worsen, and the rest had no improvement. Clinical complications were observed in only 1 patient in the WALLGRAFT group and in 2 patients in the WALLSTENT group. These preliminary results indicate very good technical and early success at the 1-month follow-up with the use of the WALLGRAFT Endoprosthesis in complex iliac artery stenosis and occlusion. Despite these promising preliminary results, a longer follow-up study with a larger number of patients is needed to determine the benefits of the WALLGRAFT Endoprosthesis in patients with complex iliac artery stenosis or occlusion.

Update on endovascular treatment of peripheral vascular disease: new tools, techniques, and indications.

The treatment of peripheral vascular disease is one of the most rapidly expanding fields of medicine today At one time, patients who had peripheral vascular disease had few medical or surgical options. Now, however, options abound. The number of peripheral interventions increased from 90,000 in 1994 to more than 200,000 in 1997 and endovascular techniques may soon replace up to 50% of traditional vascular operations. Cardiologists, interventional radiologists, and vascular surgeons bring various types of expertise to endovascular intervention; nonetheless, they seem to share similar levels of enthusiasm about this treatment option. The many advantages to the patient that such intervention offers over traditional surgery, such as the avoidance of anesthesia and other surgical risks, the rapid recovery time, and the relatively low treatment costs, provide encouragement to these specialists. Endovascular intervention requires dedication on the part of practitioners, because it demands such complete knowledge of vascular disease and of the anatomic changes experienced by the patient. The challenge is intensified by the continual introduction of new products and methods. We hope, herein, to offer pertinent information about recent advances in interventional techniques and devices, and to provide a framework for future education.

Hypertrophic cardiomyopathy and associated coronary artery disease.

Eighty-five consecutive patients with hypertrophic cardiomyopathy underwent hemodynamic evaluation and coronary arteriography to determine, in each case, the incidence and importance of coronary artery disease (CAD). Sixteen patients (19%) had >60% narrowing of the luminal diameter of one or more coronary arteries. Our findings revealed that patients with CAD were significantly older (mean, 64 years) than patients without CAD (mean, 42 years) and had a higher incidence of angina pectoris (81% versus 44%). Left ventricular end-diastolic pressures were lower in patients with CAD (mean, 17 mm Hg) than in those without CAD (mean, 23 mm Hg). The electrocardiographic findings were similar in both groups. There was no operative mortality in either group. In five patients with severe stenosis of the left anterior descending coronary artery (>90%), no collaterals to that artery were seen. In two, filling of the narrowed artery appeared slower than usual. Our study indicates that in patients older than 45 years of age with hypertrophic cardiomyopathy, the incidence of CAD is significantly higher, and warrants coronary arteriography prior to consideration for cardiac surgery. In this study, patients with hypertrophic cardiomyopathy and CAD who underwent corrective surgery for hypertrophic cardiomyopathy concomitantly with coronary artery bypass surgery have had low operative and long-term mortality with long-lasting symptomatic improvement.

Thrombolytics and left-sided prosthetic valve thrombosis. A case report.

Prosthetic valve thrombosis is a well-known condition. Because surgical treatment of prosthetic valve thrombosis is associated with a high mortality rate, the use of thrombolysis as therapy for this condition has gained popularity in recent years. In this article, we discuss the cases of 3 patients who presented to our institution with left-sided prosthetic valve thrombosis between 1994 and 1997. All 3 patients presented with New York Heart Association functional class III or IV symptoms, and all were successfully treated with urokinase. The use of thrombolytic therapy for left-sided prosthetic valve thrombosis is associated with low mortality rates, and therefore is an attractive alternative to valve replacement or thrombectomy. However, the risk of embolic and hemorrhagic complications precludes the use of thrombolysis in patients with large thrombi and in those with New York Heart Association functional class I and II symptoms; for these patients, the risk associated with thrombolysis exceeds surgical mortality rates.