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Biomedical subjects

B Waller

Publications and source records attributed to B Waller.

16 recordsLinked to original sources
PubMed1996

Late coronary artery stenosis regression within the Gianturco-Roubin intracoronary stent.

The late angiographic outcome of the Gianturco-Roubin intracoronary stent has not been well defined. To investigate serial changes within the stent, we studied 23 patients (15 men and 8 women, median age 63) who had late angiographic follow-up ( > 1 year) after undergoing Gianturco-Roubin stenting for angioplasty-associated acute or threatened native coronary artery closure. Coronary angiography before and after stenting, at 6-month follow-up, and at late return was analyzed with quantitative coronary angiography. The median time from stent deployment to late angiographic follow-up was 27 months. As expected, stenting significantly increased the median minimal lumen diameter (MLD) acutely from 1.0 to 2.46 mm. Median percent diameter stenosis decreased from 66% to 18%. Although at 6 months there was a significant loss of the acute gain (median MLD decreased from 2.46 to 1.9 mm), with a corresponding increase in percent stenosis from 18% to 31%, late angiography demonstrated lesion regression, median MLD increasing from 1.9 to 2.15 mm (p = 0.004), and percent stenosis decreasing from 31% to 21% (p = 0.0026). No patient had a significant decline in minimal lesion diameter, and 5 patients had a > 50% increase in MLD at late follow-up. Linear regression analysis of 6-month MLD and late lumen gain suggested that lesions with the greatest regression were those with the lowest lumen diameters at 6-month angiography. Late angiographic analysis demonstrated significant lesion regression within the Gianturco-Roubin stent, which was sometimes dramatic. In suggesting that coronary arteriography at 6 months may underestimate the late angiographic benefit of intracoronary stenting, these data have important clinical implications, and imply that patients with a stable clinical course and angiographic stent restenosis may often be followed rather than routinely redilated.

Angioplasty, Balloon, Coronary↗
PubMed1995

Microwave ablation of canine atrial tachycardia induced by aconitine.

We tested the efficacy of microwave-frequency energy for ablating atrial tachycardia in eight open-chest dogs. Five other dogs served as controls. Atrial tachycardia was induced by direct application of aconitine crystals to the epicardial atrial surface or by injection of aconitine solution (0.15 mg/ml) into the right or left atrial myocardium. Atrial tachycardias (n = 15) developed at a cycle length of 253 +/- 64 msec or within 245 +/- 116 sec after topical application or injection of aconitine. Catheter ablation was attempted on 10 atrial tachycardias in 8 experiment dogs by using continuous, unmodulated microwave energy from a 915 MHz frequency signal generator via a 7F helical or whip antenna catheter. Successful ablation was defined as conversion of atrial tachycardia to sinus rhythm during delivery of microwave energy and maintenance of sinus rhythm for > 5 minutes after termination of energy delivery. All 10 atrial tachycardias were successfully ablated by 2.3 +/- 1.6 applications of microwave energy for each atrial tachycardia induced. Forward microwave power level was 50.5 +/- 8.1 W, and the duration of energy application was 25.0 +/- 27.6 seconds. Sinus rhythm resumed 9.5 +/- 9.2 seconds after the onset of microwave energy application. After a mean follow-up of 10.4 minutes, seven atrial tachycardias recurred, most likely the result of diffusion of aconitine beyond the perimeter of rhe ablation lesions. Atrial tachycardia did not recur in 3 of 3 dogs that had larger ablation lesion. Gross examination revealed 10 demarcated round or oval transmural lesions in the right or left atrium, ranging from 12.6 to 105.6 mm2 in area.(ABSTRACT TRUNCATED AT 250 WORDS)

Aconitine↗
PubMed1994

General concepts in the morphologic assessment of operatively excised cardiac valves--Part I.

This two-part article discusses the general morphologic assessment of operatively excised cardiac valves and applies these principles to functional classifications. All cardiac valves are categorized into stenotic and purely regurgitant (no element of stenosis) groups based upon structural features: presence or absence of commissural fusion, calcific deposits, and degree and location of fibrosis. Of 2980 operatively excised cardiac valves reviewed between 1962 and 1992, the most common lesion was aortic stenosis, followed by mitral stenosis and the combination of aortic and mitral stenosis.

Heart Valve Diseases↗
PubMed1994

Pathology of aortic valve stenosis and pure aortic regurgitation. A clinical morphologic assessment--Part I.

This two-part article examines the histologic and morphologic basis for stenotic and purely regurgitant aortic valves. Part I discusses stenotic aortic valves and Part II will discuss causes of purely regurgitant aortic valves. In over 95% of stenotic aortic valves, the etiology is one of three types: congenital (primarily bicuspid), degenerative, or rheumatic. Other rare causes of stenotic aortic valves include active infective endocarditis, homozygous type II hyperlipoproteinemia, and systemic lupus erythematosis. The causes of pure aortic regurgitation are multiple but can be separated into diseases affecting the valve (normal aorta) (infective endocarditis, congenital bicuspid, rheumatic, floppy), diseases affecting the walls of aorta (normal valve) (syphilis, Marfan's, dissection), disease affecting both aorta and valve (abnormal aorta, abnormal valve) (ankylosing spondylitis), and diseases affecting neither aorta nor valve (normal aorta, normal valve) (ventricular septal defect, systemic hypertension). Diseases affecting the aortic valve alone are the most common subgroup of conditions producing pure aortic valve regurgitation.

Adolescent↗
PubMed1994

General concepts in the morphologic assessment of operatively excised cardiac valves--Part II.

This 2-part article discusses general morphologic assessment of operatively excised cardiac valves and applies these principles to functional classifications. All cardiac valves are categorized into stenotic and purely regurgitant (no element of stenosis) groups based upon structural features: presence or absence of commissural fusion, calcific deposits, and degree and location of fibrosis. Of 2,980 operatively excised cardiac valves reviewed between 1962 and 1992, the most common lesion was aortic stenosis, followed by mitral stenosis and the combination of aortic and mitral stenosis.

Aortic Valve Insufficiency↗
PubMed1992

Embolus in transit.

Since the advent of echocardiography, embolus in transit, historically found during surgical exploration or on postmortem examination, has been found with increasing frequency on antemortem examination. There is an inherent high mortality rate with this condition and awareness of the association between deep venous thrombosis and embolus in transit is paramount. On echocardiography the embolus is typically seen as a pleomorphic mass moving in a tumbling fashion. The most frequent symptoms are dyspnea and near syncopal episodes. The most common signs are diastolic "tumor plop" and a systolic ejection murmur heard on auscultation. Despite the success of some medical interventions, surgery should be strongly considered in patients with embolus in transit.

Aged↗
PubMed1992

Histological and angiographic effects of a pulsed holmium:YAG laser in normal and atherosclerotic human coronary arteries and aorta.

OBJECTIVE: The aims were (1) To determine the histological and angiographic effects of holmium:YAG laser energy delivered through clinical multifibre laser catheters on fresh cadaveric coronary arteries; and (2) to relate the placement of optical fibres in the catheter to patterns of tissue ablation in cadaveric aorta. METHODS: Eight fresh cadaveric hearts and segments of aorta were used. Hearts were mounted on a new pressure perfusion device. The laser catheter was delivered over a guidewire in the lumen until it met an area of resistance. The coronary artery lumen was perfused at approximately 100 mm Hg mean pressure. These arterial areas were identified on angiography, marked, and then exposed to laser energy in the range 600-3000 mJ.mm-2. Normal and atherosclerotic areas of fresh cadaveric aortic strips were exposed to increasing laser energies using either constant or increasing fluence. Coronary arteries were pressure perfused with formalin for 18-24 h at 100 mm Hg mean pressure, and aortic strips were immersed in 5% formalin. Light and scanning electron microscopy studies were carried out. RESULTS: There were no perforations or dissections by angiography in the fresh coronary arteries. One of 15 normal coronary artery segments and 10 of 16 of the pressure perfused, fixed, atherosclerotic coronary artery segments showed thermal changes associated with atherosclerotic plaque ablation. In aortic tissue, thermal effects extended 0 to 0.6 mm lateral to the ablated crater. Acoustic effects were seen only in the aortic strips after ablation at fluences > 1000 mJ.mm-2. The "dead spaces" around the optical fibres in the catheter resulted in significant amounts of coagulated tissue fragments remaining in the crater. CONCLUSIONS: Holmium:YAG laser energy delivered through multifibre catheters ablated atherosclerotic tissue in coronary arteries with minimal damage to the normal walls. The cadaveric coronary artery perfusion apparatus is useful for assessing catheter delivery and mobility and the effects of laser energy on the coaxially orientated normal and atherosclerotic coronary arterial wall.

Aorta↗
PubMed1991

Long-term follow-up of Ewing's sarcoma of bone treated with combined modality therapy.

Between 1968 and 1980, 107 consecutive patients with Ewing's sarcoma of bone were entered on three sequential combined modality treatment protocols (S2, S3, S4) at the National Cancer Institute (NCI). Protocol treatment involved 4 cycles of two drug [cyclophosphamide (CTX) and vincristine (VCR)] or three drug [CTX and VCR with either actinomycin-D (ACT-D) or doxorubicin (ADR)] regimens and local irradiation (50 Gy) to the involved bone. Eighty patients presented with localized disease and 27 patients had metastatic disease at presentation, including 11 patients with multiple metastatic sites. With a median potential follow-up of greater than 15 yrs (range 8-20 yrs), 28 pts (27%) remain alive. Disease-free (DFS) and overall survival (OS) decreased most rapidly during the initial 5 yrs of follow-up with 5-yr DFS of 29% and 5-yr OS of 39%. Only two patients with metastases at presentation are long term (greater than 5 yr) survivors. For localized disease patients, the 2, 5, 10, and 15 yr DFS and OS are 52%, 37%, 35%, and 33% DFS and 68%, 51%, 39%, and 34% OS, respectively. Eleven patients relapsed locally as the first site of failure. Using the Cox proportional hazards model, four significant variables for both DFS and OS were recognized, including metastatic disease at presentation, age greater than 25 yrs, high LDH in localized disease patients, and central primary tumor in localized disease patients in decreasing order of significance. We conclude that a majority of these patients with Ewing's sarcoma of bone relapsed within 5 yrs of presentation although late relapse (5-15 yrs) did occur. Local failure occurred in 20% of patients using these combined modality treatments but had no impact on overall survival.

Adolescent↗
PubMed1990

The natural history of intimal flaps in a canine model.

The natural history of arterial intimal flaps has not been well defined. This study characterizes the natural history of unrepaired intimal flaps. Thirty-nine 1-, 2-, and 3-mm hemispheric, distally based intimal flaps were made in 4- to 5-mm diameter canine femoral and carotid arteries. Twenty arteries had 2- and 3-mm intimal flaps and were monitored for short-term arterial thrombosis and flap extension. Nineteen had 1- and 2-mm intimal flaps and were monitored for thrombosis, long-term development of neointimal hyperplasia, arterial stenosis, and persistence of the flap. While 40% of the arteries with 3-mm intimal flaps developed thrombosis in 3 to 5 days, only 3% of the arteries with 1- or 2-mm intimal flaps developed thrombosis. Most 1- to 2-mm intimal flaps resolved and the subsequent development of neointimal hyperplasia or arterial stenosis was minimal. Arteries with hemodynamically significant stenoses from intimal flaps warrant repair, while arteries with smaller intimal flaps may not require repair.

Animals↗
PubMed1987

Pathogenesis of aneurysm formation opposite prosthetic patches used for coarctation repair. An experimental study.

Patch graft angioplasty for coarctation repair has been associated with late aneurysm formation opposite the prosthetic patch in some patients. Etiologic possibilities for this aneurysm formation include congenital abnormality of the aortic wall, surgical interruption of the vasa vasorum, intimal disruption because of extensive excision of the coarctation web, and rigidity of the prosthetic patch. To assess the effect of extensive intimal excision on the development of aneurysms, we operated on 12 dogs, performing a left thoracotomy and aortoplasty with Dacron (n = 6) or polytetrafluoroethylene patches (n = 6) and concomitant intimal excision opposite the patch. Ten control dogs underwent angioplasty with Dacron (n = 5) and polytetrafluoroethylene patches (n = 5) without excision of the intima. Serial aortograms of all animals showed aneurysm formation of the aorta opposite the patch in eight of the 12 dogs undergoing intimal excision. In contrast, no aneurysms developed in the control dogs (p less than 0.001). An additional five dogs underwent longitudinal aortotomy, intimal excision, and primary closure. Three dogs in this group demonstrated an aneurysm angiographically (p less than 0.02). Histologic analysis of the aneurysms and the control aortas revealed hyperplastic ingrowth of the intima over the denuded surface in the animals undergoing intimal excision. The elastic fibers in the media were intact and organized except in two aneurysmal specimens. We conclude that extensive resection of the intima with or without patch angioplasty predisposes aneurysm formation opposite the aortotomy and should be avoided during coarctation repair.

Animals↗
PubMed1986

Acute congestive heart failure due to the arteritis of rheumatoid arthritis: early diagnosis by endomyocardial biopsy: a case report.

A 49-year-old man with rheumatoid arthritis presented with acute congestive heart failure. Acute viral myocarditis was suspected clinically as a Gallium-67 myocardial scan was positive. Percutaneous catheter-directed biopsy of the right ventricular endomyocardium, however, revealed heavy endothelial deposits of IgM in the small blood vessels of the myocardium. Prednisone therapy resulted in normalization of both the myocardial Gallium-67 scan and left ventricular ejection fraction with resolution of the symptoms of congestive heart failure. This is the first report documenting rheumatoid arteritis antemortem by myocardial biopsy.

Arteritis↗
PubMed1985

Externally stented polytetrafluoroethylene valved conduits for right heart reconstruction. An experimental comparison with Dacron valved conduits.

Valve-containing conduits have made possible the repair of many congenital anomalies that involve right ventricular-pulmonary arterial discontinuity. The distressing problem of neointimal peel formation with eventual conduit obstruction in patients with Dacron valved conduits has led to the need for premature replacement in many patients. Externally stented polytetrafluorethylene has demonstrated superior patency in the venous system experimentally and clinically and was believed to have potential advantages over Dacron for conduit construction. This study compares the transconduit resistance and the thickness of the neointimal peel in right ventricular-pulmonary arterial conduits constructed of externally stented polytetrafluoroethylene with those of woven Dacron. The 19 mm externally stented polytetrafluoroethylene conduits (Impra, Inc.) containing a Hancock porcine valve (Extracorporeal Inc.) were implanted in six adult mongrel dogs followed by proximal occlusion of the pulmonary artery. In six additional animals, a Dacron valved conduit of similar size and length was inserted. Cardiac output, transconduit gradient, and resistance were measured at operation and at 3 months. All conduits were subsequently explanted, opened longitudinally, and the thickness of the neointimal peel (excluding suture lines) measured. No hemodynamic differences were noted during the 3 month follow-up. However, the thickness of the neointimal peel was fourfold greater in Dacron conduits (609 +/- 144 mu) than in the conduits constructed of externally stented polytetrafluoroethylene (156 +/- 50 mu) (p less than 0.01). The thick peel in Dacron conduits extended into the outflow portion of the porcine valve cusps and prevented their full excision. The neointima in externally stented polytetrafluoroethylene conduits was thin and uniform and did not extend onto the leaflets or limit their mobility. This study demonstrated that the early hemodynamic performance of externally stented polytetrafluoroethylene conduits was comparable to that of Dacron conduits; Dacron conduits were subject to an accelerated rate of peel formation that affected leaflet mobility and may be a factor in early valve degeneration; a thin neointima formed in externally stented polytetrafluoroethylene conduits and valve leaflet motion was preserved. This study showed that externally stented polytetrafluoroethylene conduits offer advantages over Dacron valved conduits and warrant clinical application.

Animals↗
PubMed1984

Second malignant neoplasms complicating Hodgkin's disease: the National Cancer Institute experience.

The medical records of all patients treated for Hodgkin's disease during the years 1964-1981 were reviewed. Four hundred seventy-three previously untreated patients were analyzed. Thirty-four subsequent second malignant neoplasms were observed in 33 patients among those treated for Hodgkin's disease. Eight cases of acute nonlymphocyctic leukemia, one case of chronic myeloid leukemia, three cases of non-Hodgkin's lymphoma, three cases of sarcoma, and 19 other tumors were identified. The ten-year estimated risk of leukemia by treatment was the following: radiotherapy only (0), chemotherapy only (0.02), initial combined radiotherapy-chemotherapy (0.06), and salvage combined radiotherapy-chemotherapy (0.09). The ten-year estimated risk of solid tumors was 0.07 overall, with all treatment groups associated with similar risks. Unlike some other reports, a greater risk of leukemia in patients who began treatment for Hodgkin's disease at age 40 or older was not found. However, a positive association was noted between increasing risk of solid tumors and increasing patient age.

Adolescent↗