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D C Miller

Publications and source records attributed to D C Miller.

At least 109 records · Page 6Linked to original sources
PubMed1997

Effects of mechanical left ventricular support on right ventricular diastolic function.

BACKGROUND: Previous studies have shown that left ventricular (LV) unloading alters right ventricular (RV) systolic mechanics, but the effects of LV assist device (LVAD) support on RV diastolic function have not been examined in intact subjects. METHODS: Seven closed-chest, sedated dogs were studied after placement of a LVAD and 27 myocardial markers; in four animals, a right coronary artery occluder was placed to induce acute RV free wall ischemia. Data were recorded with the LVAD off and LVAD on before (control) and during RV ischemia. Assessment of RV diastolic function included RV myocardial relaxation (time constant of isovolumic pressure decay [tau]), RV chamber stiffness (slope of the end-diastolic pressure-volume relation), and RV filling dynamics (peak filling rate and mean filling rate during early diastole). RESULTS: During control, full LVAD support did not alter RV tau (104 +/- 67 msec LVAD off versus 109 +/- 49 msec LVAD on, p > 0.50), RV diastolic stiffness (0.56 +/- 0.31 versus 0.51 +/- 0.25 mm Hg/ml, p > 0.20), peak filling rate (107 +/- 51 versus 119 +/- 82 ml/sec, p > 0.35) or mean filling rate during early diastole (32 +/- 28 versus 27 +/- 18 ml/sec, p > 0.40). With right coronary artery occlusion, RV tau rose to 136 +/- 33 msec (p < 0.001), and RV diastolic stiffness fell to 0.29 +/- 0.13 mm Hg/ml (p < 0.005), but there was no change in RV filling rates (p > 0.20). With mechanical LV support during acute RV ischemia, there was no additional change in RV tau, diastolic stiffness, or filling dynamics (p > 0.20). CONCLUSIONS: In intact animals, RV ischemia impaired RV relaxation and decreased chamber stiffness, but there was no change in RV filling rates. Mechanical LV support, during the control state and with RV ischemia, did not affect RV diastolic performance.

Animals↗
PubMed1997

Ascending aortic aneurysm and aortic valve disease: what is the most optimal surgical technique?

The merits of separate versus composite valve graft replacement for the treatment of patients with ascending aortic aneurysms or dissections associated with aortic valve disease remain a controversial issue. Considering all available clinical data, the early and late results surprisingly are quite similar between the two procedures. However, patient selection criteria and operative technique are important. In patients with the Marfan syndrome and in those with significantly diseased or destroyed sinuses, composite valve graft replacement is the procedure of choice. The "open" (Carrel button) method of coronary reimplantation is recommended in almost all cases to minimize the risk of late false aneurysm formation. If the aortic leaflets are normal, a valve-sparing aortic root remodeling procedure is a reasonable alternative in certain individuals. Separate valve graft replacement is still a satisfactory option in other (non-Marfan) patients; however, most of the sinuses should be resected, leaving only small tongues of aortic wall surrounding the coronary ostia to reduce the risk of late aortic root aneurysmal degeneration. In patients with complex prosthetic valve endocarditis or multiple paravalvular leaks, homograft aortic root replacement is a good option after radical debridement of all infected or devitalized tissue.

Aortic Dissection↗
PubMed1997

Desmoplastic infantile astrocytoma with metastases at presentation.

A 4-month-old child presented with nystagmus and macrocephaly. He had a large tumor in the suprasellar and hypothalamic region, as well as two smaller similar masses in the posterior fossa and one in the spinal canal. A biopsy of the suprasellar mass revealed it to be a desmoplastic infantile cerebral astrocytoma. Cerebrospinal fluid obtained at surgery before tumor manipulation showed clusters of malignant cells immunopositive for glial fibrillary acidic protein. In our opinion, the smaller tumors were metastases from the large suprasellar primary astrocytoma. Review of all of the previously reported cases of desmoplastic infantile cerebral astrocytoma and of the related neoplastic entity desmoplastic infantile ganglioglioma suggested that this was a unique case, but we still recommend caution with respect to the previously accepted notion that desmoplastic infantile neuroepithelial tumors are virtually benign neoplasms.

Astrocytoma↗
PubMed1997

Continuing dilemmas concerning aortic valve replacement in patients with advanced left ventricular systolic dysfunction.

Aortic valve replacement in patients with aortic stenosis or aortic regurgitation who have severe left ventricular (LV) systolic dysfunction continues to be associated with a high mortality risk despite surgical, cardiological and anesthetic improvements over time. As a result of earlier surgical referral, however, fewer patients with aortic regurgitation (AR) and advanced LV failure present for operation today. Favorable operative and long-term results, and data demonstrating recovery of LV systolic function if patients are referred prior to the onset of systolic dysfunction have largely solved this problem in the context of AR. On the other hand, patients with critical aortic stenosis (AS) and severe LV systolic dysfunction constitute a more heterogeneous and even more challenging group. On one side of the continuum, patients with truly critical AS and low ejection fraction due to LV 'afterload mismatch' (depressed ejection performance resulting from excessively high systolic LV wall stress secondary to a very tight valve) generally respond well to aortic valve replacement, which immediately normalizes LV afterload. Conversely, patients with 'critical' aortic stenosis and advanced LV systolic dysfunction who present with a low transvalvular gradient and cardiac output constitute a subgroup at high operative risk, which also has a suboptimal prognosis after aortic valve replacement. This clinical situation has been termed the 'Gorlin Conundrum', and is punctuated by a low mean transvalvular gradient and low flow. The reason for the low transvalvular gradient is not always known, but can be secondary to some type of coexistent cardiomyopathy. Patients with only mild pathologic aortic valve sclerosis/stenosis and markedly depressed LV systolic function are frequently judged to have 'critical' aortic stenosis (AVA < 0.8 cm2 or AVAI < 0.4 cm2/m2) due to inherent flaws in the Gorlin equation and limitations of the Doppler continuity equation. Although alternative diagnostic techniques have been proposed, e.g. aortic valve resistance, stroke work loss, none has yet proven to be totally reliable. The suboptimal results of aortic valve replacement in low-gradient AS patients underscore our difficulty in currently predicting which patients will benefit from valve replacement. Newer diagnostic techniques, including dobutamine echocardiography, and novel new findings regarding the basic molecular mechanisms responsible for contractile dysfunction in pressure overload hypertrophy may ultimately improve the results of surgical treatment in these patients.

Aortic Valve Insufficiency↗
PubMed1997

Stent-graft repair of thoracic aortic aneurysms.

Aneurysmal disease of the thoracic aorta continues to be a very challenging management problem for physicians because of the many comorbidities harbored by these patients, as well as the morbidity of the conventional open repair via left thoracotomy. In a combined effort between interventional radiology and cardiovascular surgery, an endovascular stent graft repair has been devised for these patients in an effort to reduce morbidity. This report documents the results in the first 108 patients so treated. The graft itself, custom-made for each individual, is composed of interlocked, self-expanding "Z" stents covered with a woven Dacron graft. Compressed in a loading capsule, the graft can then be advanced through a 27-French (outside diameter; OD) sheath, which is positioned within the aneurysm under fluoroscopic guidance. Relatively normal 2- to 3-cm segments of proximal and distal aorta allow an adequate friction seal to prevent stent graft dislodgement and also provide a hemostatic seal to obliterate aneurysm filling. Complete aneurysm thrombosis was achieved primarily in 103 patients. There were 10 deaths (9.25%) within the first 30 days, four of which were directly attributable to the stent graft procedure. Perioperative strokes occurred in four patients, and there were four instances of paraplegia. There have been two documented stent graft failures in a mean follow-up of 21.8 months (range, 1 to 57 months). Although the long-term durability of this procedure remains unknown, we believe this less invasive endovascular approach will prove to be an effective and less morbid treatment for aneurysmal disease of the descending thoracic aorta.

Aortic Aneurysm, Thoracic↗
PubMed1996

Effects of chordal disruption on regional left ventricular torsional deformation.

BACKGROUND: Chordal excision during mitral valve replacement (MVR) impairs left ventricular (LV) systolic function, but the mechanisms responsible for this change remain unclear. This study was performed to determine the influence of annular papillary continuity on regional LV torsional deformation acutely following MVR with and without chordal preservation. METHODS AND RESULTS: Twenty-seven dogs underwent placement of LV subepicardial myocardial markers to measure regional LV systolic torsional deformation throughout the left ventricle. After 1 week, biplane fluoroscopic marker images were obtained pre-MVR in the baseline state and with inotropic stimulation (calcium, 15 mg/kg). Dogs were then randomized to undergo a sham procedure with cardiopulmonary bypass but no valve replacement (n = 6), conventional MVR with chordal excision (n = 7), or chordal-sparing MVR with preservation of the posterior leaflet and reattachment of the anterior leaflet chordae to either the anterior annulus (n = 7) or posterior annulus (n = 7). After chest closure and recovery from anesthesia, post-MVR data were acquired. At the LV apical level, maximal regional LV systolic torsional deformation (theta max) did not fall from pre-MVR values in the baseline state after the sham procedure or anterior or posterior chordal-sparing MVR procedure (P > or = .10). After conventional MVR, baseline theta max fell by 66% to 81% in the anteroseptal, anterior, anterolateral, and lateral regions (P < .05). With calcium, theta max fell in the anteroseptal through lateral regions and the septal wall (P < .05) but did not change in the posterior regions (P > or = .10). With calcium, theta max did not fall in any region after either the sham procedure or anterior MVR; however, after posterior chordal-sparing MVR, theta max fell in the lateral, posterior, and posteroseptal regions (P < .05). CONCLUSIONS: Sham operation and anterior chordal-sparing MVR did not affect regional LV torsion; however, loss of normal valvular-ventricular integrity with conventional MVR reduced regional LV systolic torsion in the anterior and lateral LV regions. Posterior chordal-sparing MVR impaired torsion only after calcium administration. The deleterious effects of chordal excision may be due in part to perturbation of regional systolic torsional deformation.

Animals↗
PubMed1996

Loss of three-dimensional canine mitral annular systolic contraction with reduced left ventricular volumes.

BACKGROUND: We have recently described an inhomogeneous pattern of systolic contraction of the mitral annulus (MA) in normovolemic dogs: the posterior annulus shortens, and the anterior annulus lengthens. MA dynamics, however, have not been studied in volume-depleted hearts. METHODS AND RESULTS: Eight radiopaque markers were placed equidistant from each other around the MA in seven dogs. As viewed from the left atrium, the segment between markers 1 and 2 (seg12) began at the posteromedial commissure, and remaining segments were numbered sequentially clockwise around the MA (ie, posterior MA encompassed seg12, seg23, seg34, and seg45; anterior MA encompassed seg56, seg67, seg78, and seg81). Marker images were obtained in sedated dogs by simultaneous biplane videofluoroscopy 7 to 12 days after marker implantation, and three-dimensional marker coordinates at end diastole (ED) and end systole (ES) were computed. Vena caval occlusion (VCO) was used to reduce left ventricular end-diastolic volume to 70 +/- 5% of baseline (BL). With VCO, mean MA area did not change from ED to ES (3.4 +/- 0.8 versus 3.6 +/- 0.7 cm2, P = NS) during the cardiac cycle. MA segmental systolic shortening values (negative values indicate lengthening) were as follows for BL and VCO, respectively (mean +/- SD): seg12, 7 +/- 9% and 0 +/- 13%; seg23, 8 +/- 10%* and 1 +/- 11%; seg34, 16 +/- 6%* and 4 +/- 9% seg45, 10 +/- 7%* and 2 +/- 13%; seg56, -4 +/- 5%* and -16 +/- 11%*; seg67, -7 +/- 7%* and -14 +/- 7%*; seg78, 3 +/- 2%* and -1 +/- 6%; and seg81, 6 +/- 5%* and -5 +/- 11% (*P < or = .05 versus zero changes, paired t test). CONCLUSIONS: With acute volume depletion, the five annular segments that shortened at BL no longer changed length; two anterior segments (seg56 and seg67) that lengthened at BL continued to lengthen significantly, and to a greater extent. These findings indicate that the anterior MA is a more dynamic structure than previously thought. Such dynamic motion may be important for normal mitral valvular function and possibly needs to be taken into account in the design of mitral valve reparative techniques.

Animals↗
PubMed1996

Three-dimensional dynamic geometry of the normal canine mitral annulus and papillary muscles.

BACKGROUND: Despite an incomplete knowledge of the geometry and dynamics of the mitral annulus (MA), papillary muscle (PM), and the chordae tendineac, chordal-sparing MVR is popular. METHODS AND RESULTS: The systolic reduction in three-dimensional distance between each PM tip and eight MA sites (DT-A) was measured in nine normal closed-chest dogs by use of surgically implanted radiopaque markers. Three loci (tip, junction, and base) on each PM were also projected onto the MA plane at end diastole and end systole to assess PM dynamics. The anterior PM tip showed significant shortening of DT-A toward the opposite side of the MA or the midanterior MA region (P < .005 or P < .05, respectively, versus same MA side [MANOVA]); conversely, the posterior PM tip DT-A shortened toward the opposite side of the MA near the anterior commissure or the area between the anterior commissure and midposterior MA (P < .005 versus same MA side). Annular projection revealed three-dimensional motion (relative to the MA) of the anterior PM tip, junction, and base toward the right trigone, while posterior PM motion was oriented toward the opposite side of the MA. CONCLUSIONS: Both PMs in normal canine hearts demonstrated systolic relative motion in a direction compatible with the "oblique" chordal configuration, ie, from the anterior PM to the anterior MA near the right trigone and from the posterior PM to the opposite side of the posterior MA. These observations warrant further investigation of three-dimensional PM-MA dynamics with various methods of chorda preservation during MVR to assess their impact on left ventricular systolic and diastolic function.

Animals↗
PubMed1996

Epidemiologic study of decubital ulcers in sows.

OBJECTIVE: To determine prevalence and risk factors for decubital ulcers of the shoulder in sows. DESIGN: Descriptive cross-sectional study. SAMPLE POPULATION: All females of breeding age in a large confinement swine facility. PROCEDURE: 1,916 females were examined for lesions of the skin over the tuber of the spine of the scapula and for body condition scoring. Observational data were combined with sow data (parity, date of farrowing, litter size) contained in computerized records. RESULTS: Decubital ulcers were observed in 8.3% of females, predominantly lactating sows. Ulcer prevalence was strongly associated with time after farrowing. Lesions apparently healed rapidly after weaning. Ulcer prevalence was associated with low body condition scores, but was not associated with parity. IMPLICATIONS: Decubital ulcers are a multifactorial condition. Housing on concrete floors per se did not result in ulcers. Prolonged recumbency during parturition, reduced activity in early lactation, periparturient illness, thin body condition, moist skin, and floor type are potential risk factors.

Animal Nutritional Physiological Phenomena↗
PubMed1996

Radiographic detection of single strut leg separations as a putative basis for prophylactic explantation of Björk-Shiley convexo-concave heart valves.

Cineradiography, using higher kVp and two or more specified profiles for each outlet strut leg, was used to evaluate Björk-Shiley convexo-concave (C/C) heart valves with epidemiologically defined > 0.1% per year estimated fracture rates. Among 828 mitral valves, eight radiographs were assessed as definite single leg separations (SLS) and 23 were read as probable SLS. Explantation confirmed SLS in 24 valves; 4 probables were false positives, and 3 patients with probable SLS ratings decided against explantation. Four patients with SLS died, an operative mortality of 14%. Only 23 mitral and 6 aortic valves receiving ratings ranging from apparently normal to suspicious have become available for verification; 1 rated apparently normal was found to have a SLS. Two patients experienced fatal fractures and 1 SLS valve was explanted 3 to 15 months after apparently normal x-ray studies; it cannot be known if a SLS was or was not present at the time of these examinations. As 97% of negatively rated valves remain in situ, the sensitivity of the test is similarly not known. Only 1 SLS has been detected among 136 aortic valves. Uncertainty about test accuracy and SLS progression condition the clinical utility of radiographic SLS detection, particularly with respect to assurance from apparently normal readings. However, radiographic identification of an SLS substantially enhances epidemiologically derived risk categorization as a basis for consideration of prophylactic replacement for the approximately 12,000 valves with a > 0.1% estimated annual fracture risk, currently thought to be implanted in living patients.

Aortic Valve↗
PubMed1996

Three-dimensional dynamics of the canine mitral annulus during ischemic mitral regurgitation.

BACKGROUND: It has been suggested that ischemic mitral regurgitation results, at least in part, from generalized end-systolic mitral annulus (MA) dilatation, but the role of the MA is incompletely understood and the segmental dynamics of the MA during left ventricular ischemia have not been described. METHODS: We used radiopaque markers and simultaneous biplane videofluoroscopy to measure three-dimensional in vivo lengths of eight MA segments in 7 sedated dogs before and after induction of ischemic MR (produced by circumflex coronary artery balloon occlusion and verified by Doppler echocardiography). As viewed from the left atrium, the MA segment between markers 1 and 2 (S12) was defined as starting at the posteromedial commissure, and remaining segments were numbered sequentially clockwise around the MA (ie, the posterior MA encompassed S12, S23, S34, S45,; the anterior MA included S56, S67, S78, S81). Marker images obtained 7 to 12 days after implantation were used to construct x, y, and z coordinates of each marker at end-diastole and end-systole. RESULTS: During regional (posterolateral walls) left ventricular ischemia, the end-systolic MA area increased (4.9 +/- 0.8 cm2 [control] versus 5.9 +/- 0.6 cm2; p = 0.005). End-systolic MA segment lengths were as follows (control, ischemia [mm, mean +/- standard deviation]): S12 = 9 +/- 2, 10 +/- 3; S23 = 10 +/- 2, 12 +/- 3; S34 = 13 +/- 1, 15 +/- 1; S45 = 8 +/- 2, 9 +/- 2; S56 = 11 +/- 2, 11 +/- 2; S67 = 12 +/- 2, 12 +/- 2; S78 = 10 +/- 3, 11 +/- 2; and S81 = 11 +/- 1, 12 +/- 1. Values for S12, S23, S34, and S81 were significant (p < or = 0.05 for control versus ischemia by paired t test). CONCLUSIONS: During ischemic mitral regurgitation, the MA enlarged at end-systole, but in an asymmetric manner; most posterior annular segments lengthened, whereas most anterior annular segment lengths did not change. These data suggest that alterations in regional MA mechanics may be important in the pathogenesis of ischemic mitral regurgitation. Further three-dimensional studies of MA dynamics and shape should be conducted so that new knowledge may result in improved mitral valve surgical techniques.

Animals↗
PubMed1996

Twenty-year clinical experience with porcine bioprostheses.

BACKGROUND: For the past 25 years, porcine valves have been the most widely implanted bioprosthesis, thereby becoming the standard for comparison with newer bioprosthetic valves. METHODS: We retrospectively analyzed 2,879 patients who underwent aortic (AVR; n = 1,594) or mitral (MVR; n = 1,285) valve replacement between 1971 and 1990. Follow-up was 97% complete and extended to 20 years (total, 17,976 patient-years). Patient age ranged from 16 to 94 years; mean age in patients who underwent AVR was 60 +/- 15 (+/- standard deviation) years; that for patients who underwent MVR was 58 +/- 13 years. RESULTS: The operative mortality rates were 7% +/- 1% (70% confidence limits) for AVR and 10% +/- 1% for MVR. Actuarial estimates of freedom from structural valve deterioration at 10 and 15 years were 78% +/- 2% (SE) and 49% +/- 4%, respectively, for the AVR subgroup; and 69% +/- 2% and 32% +/- 4%, respectively, for the MVR subgroup (AVR > MVR; p < 0.05). Estimates of freedom from reoperation at 10 and 15 years were 76% +/- 2% and 53% +/- 4%, respectively, for the AVR subgroup and 70% +/- 2% and 33% +/- 4%, respectively, for the MVR subgroup (AVR > MVR; p < 0.05). Estimates of freedom from thromboembolism at 10 and 15 years were 92% +/- 1% and 87% +/- 2%, respectively, for the AVR subgroup and 86% +/- 1% and 77% +/- 3%, respectively, for the MVR subgroup (AVR > MVR; p < 0.05). Estimates of freedom from anticoagulant-related hemorrhage at 10 and 15 years were both 96% +/- 1% for the AVR subgroup and 93% +/- 1% and 90% +/- 2%, respectively, for the MVR subgroup (AVR > MVR; p < 0.05). Estimates of freedom from valve-related mortality at 10 and 15 years were 86% +/- 1% and 78% +/- 3%, respectively, for the AVR subgroup and 84% +/- 2% and 70% +/- 4%, respectively, for the MVR subgroup (p = not significant). Multivariate analysis (Cox model) showed younger age, later year of operation, and valve site (MVR > AVR) to be significant risk factors for structural valve deterioration. Younger age, later year of operation, valve site (MVR > AVR), and renal insufficiency were the significant, independent risk factors for reoperation. Multivariate analysis revealed that higher New York Heart Association functional class, longer cardiopulmonary bypass time, congestive heart failure, renal insufficiency, and longer cross-clamp time were significant risk factors for valve-related mortality. Valve manufacturer did not emerge as a factor in any analysis. CONCLUSIONS: These long-term results with porcine bioprostheses were satisfactory, particularly in older patients and those undergoing AVR. As expected, younger age was a significant risk factor for structural valve deterioration and reoperation in both groups. Surprisingly, the durability of porcine bioprosthetic valves has not improved over time, which possibly can be attributed to more enhanced postoperative surveillance and earlier reintervention. These first-generation Hancock and Carpentier-Edwards porcine bioprostheses achieved similar long-term performance.

Actuarial Analysis↗
PubMed1996

Accuracy of biplane and multiplane transesophageal echocardiography in diagnosis of typical acute aortic dissection and intramural hematoma.

OBJECTIVES: The purpose of this study was to evaluate the diagnostic accuracy of biplane and multiplane transesophageal echocardiography in patients with suspected aortic dissection, including intramural hematoma. BACKGROUND: Transesophageal echocardiography is a useful technique for rapid bedside evaluation of patients with suspected acute aortic dissection. The sensitivity of transesophageal echocardiography is high, but the diagnostic accuracy of biplane and multiplane transesophageal echocardiography for dissection and intramural hematoma is less well defined. METHODS: We studied 112 consecutive patients at a major referral center who had undergone biplane or multiplane transesophageal echocardiography to identify aortic dissection. The presence, absence and type of aortic dissection (type A or B, typical dissection or intramural hematoma) were confirmed by operation or autopsy in 60 patients and by other imaging techniques in all. The accuracy of transesophageal echocardiography for ancillary findings of aortic dissection (intimal flap, fenestration and thrombosis) was assessed in the 60 patients with available surgical data. RESULTS: Of the 112 patients, aortic dissection was present in 49 (44%); 10 of these had intramural hematoma (5 with and 5 without involvement of the ascending aorta). Of the remaining 63 patients without dissection, 33 (29%) had aortic aneurysm and 30 (27%) had neither dissection nor aneurysm. The overall sensitivity and specificity of transesophageal echocardiography for the presence of dissection were 98% and 95%, respectively. The specificity for type A and type B dissection was 97% and 99%, respectively. The sensitivity and specificity for intramural hematoma was 90% and 99%, respectively. The accuracy of transesophageal echocardiography for diagnosis of acute significant aortic regurgitation and pericardial tamponade was 100%. CONCLUSIONS: Biplane and multiplane transesophageal echocardiography are highly accurate for prospective identification of the presence and site of aortic dissection, its ancillary findings and major complications in a large series of patients with varied aortic pathology. Intramural hematoma carries a high complication rate and should be treated identically with aortic dissection.

Acute Disease↗
PubMed1996

Deferring adjuvant therapy for totally resected intracranial ependymoma.

Radical surgery is the most important treatment modality for ependymoma. The benefit of adjuvant radiotherapy and/or chemotherapy following a gross total resection of a low grade intracranial ependymoma is uncertain. Since 1990 we elected to defer adjuvant therapy in 7 pediatric patients with a median age of 7 years (range 3-16 years) who had a radical resection of an intracranial ependymoma and no evidence of central nervous system metastases. The primary tumor site was the cerebral hemisphere (6) and the cerebellum (1). A gross total resection was radiologically confirmed in 5 of the 7 patients. Two of the patients had a blood clot in the resection site on the postoperative magnetic resonance imaging scan. All patients are alive after a median follow-up of 44 months and the median progression-free survival is 38+ months. Five of the patients remain in continuous remission. The 2 patients with postoperative blood clots developed subclinical local recurrences, 10 and 11 months, respectively, after diagnosis. They remain in remission for 13+ and 27+ months after subsequent radical surgical procedures. Involved field radiotherapy was administered to 1 patient. After a limited period of follow-up, radical surgery alone appears to be sufficient for the majority of children with low grade ependymomas diagnosed at > 3 years of age when postoperative imaging confirms a gross total resection. This is more likely to occur in supratentorial ependymomas arising in older children.

Adolescent↗
PubMed1996

Guidelines for reporting morbidity and mortality after cardiac valvular operations. The American Association for Thoracic Surgery, Ad Hoc Liaison Committee for Standardizing Definitions of Prosthetic Heart Valve Morbidity.

At the request of the Councils of The Society of Thoracic Surgeons (STS) and The American Association for Thoracic Surgery (AATS) the Ad Hoc Liaison Committee for Standardizing Definitions of Prosthetic Heart Valve Morbidity "revisited" the "Guidelines" published in September 1988 [1-3]. The purpose of the review was to update and clarify definitions within the guidelines and to consider recommendations made by others [4, 5]. The variety of cardiac valvular procedures has expanded since 1988; therefore, in this document the term "operated valve" indicates prosthetic and bioprosthetic heart valves of all types: operated or repaired native valves and allograft and autograft valves. The term "operated valve" includes any cardiac valve altered by a surgeon during an operation. Much morbidity and mortality is a direct consequence of the interaction between the patient and operated valve(s), although patient variables (e.g., age, degree of coronary arterial disease, follow-up care) may be more responsible for outcomes than an operated valve. However, no set of guidelines can identify all possible patient factors that may affect morbidity and mortality. General agreement regarding the following definitions of terms and suggestions for reporting data do not preclude more detailed analyses or constructive recommendations and investigators are encouraged to identify relevant patient factors in addition to factors related to operated valves.

Documentation↗
PubMed1996

Three-dimensional regional dynamics of the normal mitral anulus during left ventricular ejection.

The mitral anulus is a dynamic structure that undergoes alterations in size and shape throughout the cardiac cycle, contracting during systole. Numerous reports have shown this systolic orifice reduction to be due chiefly to posterior annular contraction, whereas the anterior perimeter was unchanged. Segmental motion of the mitral anulus from true in vivo three-dimensional data, however, has not been described. We used radiopaque markers and simultaneous biplane videofluoroscopy to measure the lengths of mitral anular segments in seven closed-chest, sedated dogs. Eight markers were placed equidistant from each other around the mitral anulus, As viewed from the left atrium, segment 1 began at the posteromedial commissure, and the remaining segments were numbered sequentially clockwise around the anulus (that is, the posterior mitral anulus encompassed segments 1 to 4 and the anterior anulus encompassed segments 5 to 8). Marker image coordinates obtained from two orthogonal views 7 to 12 days after implantation were merged to construct three-dimensional marker coordinates at end-diastole and end-systole. From end-diastole to end-systole, mean annular area decreased by 11% +/- 8% (5.5 +/- 0.9 cm2 to 4.9 +/- 0.8 cm2, p = 0.005) and perimeter by 5% +/- 4% (8.8 +/- 0.7 cm to 8.3 +/- 0.7 cm, p < 0.01). Mitral annular segmental percent systolic shortening (negative values indicate lengthening) were as follows (mean +/- standard deviation): segment 1, 7% +/- 9%; segment 2, 8% +/- 10%; segment 3, 16% +/- 6%; segment 4, 10% +/- 7%; segment 5, -4% +/- 5%, segment 6, -7% +/-7%; segment 7, 3% +/- 2%; and segment 8, 6% +/- 5%. With the exception of segment 1, all posterior (2 to 4) and two anterior (7 and 8) mitral annular segments contracted significantly (p < or = vs zero, paired t test). Two anterior annular segments (5 and 6, regions overlapping aortic-mitral continuity), however, unexpectedly lengthened during left ventricular systole. We conclude that the anterior mitral anulus may be a much more dynamic component of the mitral apparatus that previously thought. Such heterogeneous dynamic annular motion should be taken into account when various mitral valve reparative techniques are being designed.

Animals↗
PubMed1996

Endovascular stent-graft repair of thoracic aortic aneurysms.

Conventional repair of aneurysms of the descending thoracic aorta entails thoracotomy and graft interposition. For elderly patients and those with previous operations, obesity, respiratory insufficiency, or other comorbidities, such a procedure entails significant mortality and morbidity. Transluminal stent-graft placement offers an alternative approach with potentially less morbidity and quicker recovery; however, the effectiveness and durability of stent-grafts remain uncertain. METHODS: Since July 1992, thoracic aortic stent-grafts have been placed in 44 patients with a variety of pathologic conditions. Each graft was individually constructed from self- expanding, stainless-steel Z stents covered with a woven Dacron polyester fabric graft. Craft dimensions were determined from spiral computed tomographic scans. All implants were performed in the operating theater under fluoroscopic and transesophageal echocardiographic guidance. Follow-up was by computed tomography and contrast angiography in all cases. PATIENT DATA: There were 36 men and 8 women. Mean age was 66 years (range 35 to 88 years). Mean aneurysmal diameter was 6.3 cm (range 4.0 to 9.4 cm). Etiologies included 23 degenerative aneurysms, four posttraumatic aneurysms, four pseudoaneurysms, and one chronic aortic dissection. RESULTS: There were three early deaths (<30 days) and two late deaths. One early death resulted from graft failure. There were two instances of paraparesis or paraplegia, with one associated early death. A single stent was deployed in 27 patients, two stents were required in 14 patients, and three stents were required in three patients. In 23 patients, vascular access was attained through the femoral artery; abdominal aortic access, either native or graft, was necessary in the remaining 21 patients. Twelve grafts were placed in conjunction with open abdominal aortic surgical procedures. Mean follow-up (98% complete) was 12.6 months (range 1 to 34 months). One late death occurred from aneurysmal expansion and rupture in a patient with a persistent midgraft leak. The second late death may have resulted from aneurysmal rupture. Immediate thrombosis was achieved in 36 patients, and late thrombosis was achieved in three others. Failure to achieve complete aneurysmal thrombosis occurred in five patients, however, and one individual (previously noted) died of aneurysmal expansion and rupture; the remaining four are being carefully monitored. Only one patient has required conversion of the stent to an open procedure; a contained rupture of the false lumen of a chronic dissection eventually necessitated total descending thoracic aortic exclusion. CONCLUSIONS: These early results support the hypothesis that endovascular stent-graft placement may be a safe and durable treatment for selected patients with aneurysmal disease of the descending thoracic aorta. Large introducer size (26F outer diameter) and relatively limited angulation capability, as well as imprecise deployment techniques, currently limit its applicability. Distal embolization and stent migration have not been observed. Failure to achieve complete aneurysmal thrombosis may allow continued aneurysmal expansion and rupture. Further follow-up is clearly necessary to evaluate the true long-term effectiveness of this procedure.

Adult↗