PubMed Health⌕ Search

Biomedical subjects

S Colvin

Publications and source records attributed to S Colvin.

At least 19 recordsLinked to original sources
PubMed2001

Abnormal right coronary artery flow and multiple right ventricular myocardial infarctions associated with severe right ventricular systolic hypertension.

The impact of left ventricular hypertension on coronary flow patterns in adult patients has been well described. In contrast, few reports exist regarding the association of right coronary flow abnormalities with right ventricular hypertension. The observation of myocardial infarcts, right ventricular hypertension, and abnormal coronary flow pattern-as well as its normalization with relief of right ventricular hypertension-lends support to a causal relation between ventricular hypertension and coronary flow abnormalities.

Arteries↗
PubMed2001

Predictors of operative time in multicenter port-access valve registry: institutional differences in learning.

BACKGROUND: The predictors of operative time and the effects of learning in isolated valve operations using port-access techniques have not been defined. METHODS: Analysis of covariance was used to examine the determinants of procedure time, pump time, and aortic clamp time. In the largest prospective, registry of patients undergoing isolated aortic valve replacement (AVR, N=199), mitral repair (MVP, N=307), or mitral replacement (MVR, N=232) using port-access techniques 1997-1999 at 27 institutions. RESULTS: Institutional case volume ranged from one to 214 (median 6). Operative time was longer in redo procedures (5.3 +/- 1.6 vs. 4.4 +/- 1.3 hr, p = 0.0001), longer with MVP or MVR vs. AVR (4.8 +/- 1.2 vs. 5.0 +/- 1.5 vs. 3.8 +/- 1.2 hr, p = 0.0001), and decreased with case number (mean decrease 1.00 +/- 0.19 min/case, p = 0.04). Operative time also varied between institutions (p = 0.001). Rate of learning (decrease in time per case) varied significantly between institutions only for MVP (p = 0.03). Similar analysis showed that pump time and clamp times did not significantly change over time (p > 0.17) but varied significantly between institutions. Institutional volume did not affect operative, pump, or clamp times or rate of learning (decrease in operative time/case). CONCLUSIONS: These prospective registry data demonstrate that, for port-access valve procedures, procedure times continue to improve (learning) even after 100 cases. Procedure time and learning are affected by institutional differences and by the type of procedure, but are little affected by institutional volume. This data provides a model to understand learning of new surgical procedures, and this data suggests that port-access valve procedures can be mastered by a variety of institutions.

Analysis of Variance↗
PubMed1999

Inhibition of endothelial cell migration by gene transfer of tissue inhibitor of metalloproteinases-1.

BACKGROUND: Angiogenesis requires degradation of the vessel's basal lamina and endothelial cell migration into the tissue stroma. Matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play important roles in this process. MMP activity is tightly regulated during vessel growth. This work was designed to characterize the effect of TIMP-1 upregulation on endothelial cell invasion of the extracellular matrix. METHODS: We constructed replication-deficient recombinant adenoviruses that encode either TIMP-1 (Ad.TIMP-1) or Escherichia coli lac Z (Ad.beta gal) cDNA. Bovine aortic endothelial (BAE) cells were infected with 100 infectious particles/cell. Gene expression was assessed by Northern and Western blotting. TIMP-1 activity in cell-conditioned media was measured by a resorufin-labeled casein protease assay. BAE cell migration was measured by Boyden chamber assays with 0.2% gelatin-coated, 8. 0-mcm polycarbonate membranes. RESULTS: TIMP-1 was overexpressed by Ad.TIMP-1-infected BAE cells relative to control, Ad. beta gal-infected or uninfected cells. TIMP-1 activity in Ad.TIMP-1 cell-conditioned medium was 2.8-fold higher than in control cells. By Boyden chamber assays with gelatin-coated membranes, Ad. TIMP-1-infected BAE cells showed 89.97 +/-1.64% (mean +/- SEM) reduction in migration relative to Ad.beta gal-infected cells (P < 0. 02) and 90.53 +/- 1.12% relative to uninfected cells (P < 0.02). Without gelatin coating, migration was equivalent in all groups. CONCLUSION: The replication-deficient recombinant adenovirus we constructed affords rapid and efficient upregulation of functional TIMP-1 in endothelial cells. Infection results in a dramatic decrease in cell migration and invasion of extracellular matrix. Thus, such a recombinant vector may provide a useful tool for the gene therapy of vascular remodeling and inhibition of angiogenesis.

Animals↗
PubMed1998

Modulation of matrix metalloproteinase activity in human saphenous vein grafts using adenovirus-mediated gene transfer.

BACKGROUND: Neointima formation after human saphenous vein grafting (hSVG) involves several matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs). This study assessed the feasibility of modulating MMP activity in hSVGs by adenovirus-mediated gene transfer. METHODS: First, 1 x 10(9) plaque-forming units (pfu) of replication-deficient recombinant adenoviruses encoding either beta-galactosidase (ad beta gal), MMP-3 (AdMMP-3), or TIMP-1 (AdTIMP-1) were added into the lumen of hSVGs for 1 hour. After incubation at 37 degrees C for 24 hours, specimens were analyzed by immunohistochemistry, in situ zymography, and X-gal staining. RESULTS: By X-gal staining ad beta gal-infected hSVGs stained positively in the intima and occasionally in the media. Immunohistochemistry of AdMMP-3- and AdTIMP-1-infected hSVGs localized these proteins to the intima. In situ zymography showed increased MMP activity in the intima of AdMMP-3-infected hSVGs relative to AdTIMP-1- or Ad beta gal-infected vessels. CONCLUSIONS: MMP-3 and TIMP activity can be regulated in hSVGs by replication-deficient recombinant adenoviruses. We have previously demonstrated that MMP-3 or TIMP-1 transduction, or both, inhibit SMC migration in an in vitro reconstituted vessel wall. Modulation of MMP activity may thus afford high patency rates in genetically engineered hSVGs. However, adenovirus-mediated gene delivery is limited to the vessel's intima; strategies to infect medial smooth muscle cells need to be developed.

Adenoviridae↗
PubMed1996

Atrial arrhythmia following a biatrial approach to mitral valve surgery.

The biatrial approach to exposing the mitral valve during surgery has the potential for improving visualization of the valve with minimal cardiac manipulation. This procedure, involving a right atriotomy and an extended transseptal incision, may isolate the sinus node from its normal blood supply and autonomic innervation. Thirty-eight consecutive patients undergoing this procedure were examined. Twenty-two of these patients (58%) were admitted in normal sinus rhythm and 15 (40%) were in atrial fibrillation (AF) or atrial flutter. Of the 22 patients admitted in normal sinus rhythm, only 3 patients remained in this rhythm at discharge. Fourteen of the 22 patients were discharged in a slow, low atrial rhythm. All of the patients admitted in AF were discharged in AF. Of the 14 patients discharged in a low atrial rhythm, the rhythm persisted in eleven patients (80%) at a mean of 6-month follow-up. The routine use of this transseptal approach to mitral valve surgery needs further assessment in light of the predictable loss of the sinus mechanism.

Adult↗
PubMed1990

The disappearing pulmonary artery band.

A child is presented who had pulmonary artery bands that eroded or cut-through to the point where congestive heart failure and pulmonary arterial hypertension recurred. A summary of previously reported cases of band erosion or cut-through is presented, noting that many of these children died. Pulmonary artery banding is now mainly used in infants with complex defects where mortality of early repair is prohibitive or where the Fontan procedure is the only "repair" possible. To obtain good results, a normal pulmonary vascular resistance is preferred; therefore, it is important that the pulmonary artery band is truly protective over the period of time needed. The occurrence of pulmonary vascular disease can cause a decrease in left-to-right shunting and allow a child to clinically improve, thus duplicating the response to a successful banding. If noninvasive evaluation cannot provide clear-cut proof that the band is protective, then measurement of pulmonary artery pressure and flow must be done.

Child, Preschool↗
PubMed1990

Clinical evaluation of high-frequency (ultrasonic) mechanical débridement in the surgical treatment of calcific aortic stenosis.

Repair of aortic valve stenosis due to calcific degeneration may lead to hemodynamic and clinical improvement without the problems inherent with prosthetic valves. We have evaluated the use of a device capable of débriding calcium, the Cavitron ultrasonic aspirator (CUSA), as an adjunct to mechanical débridement in the repair of calcific aortic stenosis. Ten patients (five women), ages 63 to 83 years, were studied by M-mode, two-dimensional, and Doppler echocardiography before and an average of 26 (range 3 to 124) days after this procedure. The degree of calcification of the valve cusps was clearly reduced. The maximal cusp excursion increased from 0.7 +/- 0.1 cm preoperatively to 1.5 +/- 0.4 cm postoperatively (p = 0.006). The peak aortic gradient fell from 80 +/- 36 mm Hg to 28 +/- 10 mm Hg (p = 0.0007). The mean aortic gradient fell from 53 +/- 20 mm Hg to 16 +/- 5 mm Hg (p less than 0.0001). Aortic valve area calculated by the continuity equation increased from 0.6 + 0.2 cm2 to 1.6 +/- 0.6 cm2 (p = 0.0009). No patient had more than mild aortic insufficiency preoperatively. Postoperatively, color Doppler flow mapping revealed severe aortic insufficiency in two patients. Seven patients had further echocardiographic evaluation 99 (range 33 to 196) days after the procedure. These studies revealed the development of severe aortic insufficiency in an additional four patients. Four patients with severe symptomatic aortic insufficiency eventually underwent aortic valve replacement. Pathology revealed scarring and retraction of the aortic cusps. Widening of the commissures was responsible for the severe aortic insufficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Congenital fistulous tract between aorta and right atrium presenting as heart failure in a newborn.

A newborn with a fistulous communication between the right coronary sinus and right atrium had congestive heart failure on the first day of life. Medical management was unsuccessful and operative repair was performed using bypass surgery at 5 days of age. Echocardiographic evaluation preoperatively diagnosed the defect correctly and postoperatively confirmed a complete repair. Since aneurysms and/or fistulae can occur in other sinuses after an initial repair of the presenting lesion, the infant will continue to be followed with periodic echocardiographic and clinical evaluations.

Aortic Diseases↗
PubMed1986

Long-term follow-up after mitral valve reconstruction: incidence of postoperative left ventricular outflow obstruction.

Reconstructive surgery of the mitral valve has been an alternative to mitral valve replacement in patients with mitral regurgitation. Previously, we reported on postoperative left ventricular outflow tract obstruction associated with systolic anterior motion of the anterior mitral leaflet. The current study was designed to evaluate the incidence of this complication and the long-term results of mitral valve reconstructive surgery. Sixty-five patients, aged 19 to 78 years, had mitral valve reconstructive surgery. Two patients died perioperatively, and three died late after surgery. The 60 surviving patients were studied by M mode, two-dimensional, and Doppler echocardiography 1 to 55 months postoperatively (mean 21). Fifty patients had no evidence of postoperative mitral regurgitation, two patients had moderate mitral regurgitation, three patients had mild mitral regurgitation, and five patients had trace mitral regurgitation. No significant mitral stenosis was detected in any patient postoperatively. After surgery, the diameter of the left ventricular outflow tract was significantly smaller than that before surgery. The echocardiograms of six patients showed abnormal systolic anterior motion of the anterior mitral leaflet that was not observed preoperatively. Doppler echocardiography demonstrated pressure gradients across the left ventricular outflow tract between 10 and 64 mm Hg. Inhalation of amyl nitrite increased these gradients. An additional patient who had systolic anterior motion but no gradient developed a 36 mm Hg gradient after inhalation of amyl nitrite. The remaining patients had no gradient induced by amyl nitrite. Abnormal systolic anterior motion of the anterior mitral leaflet may be surgically induced by changes in left ventricular geometry and the size of the left ventricular outflow tract during systole.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

Echocardiographic evaluation of Carpentier mitral valvuloplasty.

Carpentier's technique for reconstructive mitral valve surgery is an alternative to mitral valve replacement in patients with mitral regurgitation. The procedure involves reconstruction of the mitral valve and insertion of a ring into the mitral anulus. To study the results of this operation, pre- and postoperative M-mode, two-dimensional (2DE), and Doppler echocardiography were performed on 13 patients with severe, symptomatic mitral regurgitation, who underwent reconstructive mitral surgery. A significant clinical improvement was noted in all patients. This correlated with the hemodynamic and angiographic improvement in six of the patients who underwent postoperative cardiac catheterization. Postoperative echocardiography showed that the mitral valve E-F slope decreased from 129 +/- 30 mm/sec preoperatively to 53 +/- 13 mm/sec postoperatively (p less than 0.001). The mitral valve excursion decreased from 28 +/- 6 mm preoperatively to 19 +/- 2 mm postoperatively. The left ventricular minor axis shortening decreased from 32 +/- 9% to 28 +/- 6%. In seven patients the mitral valve area decreased from 4.5 +/- 0.9 cm2 to 2.8 +/- 0.5 cm2 (p less than 0.005). In each patient a new echocardiographic finding was observed: two parallel dense linear echoes from the prosthetic ring were noted on M-mode echocardiography near the base of the mitral valve. 2DE visualized the entire ring. Doppler echocardiography suggested moderate or severe mitral regurgitation in eight of eight patients studied preoperatively. Postoperatively 10 of 11 patients had no Doppler echocardiography finding of mitral regurgitation.

Adolescent↗
PubMed1983

The effect of nitroglycerin cardioplegia on myocardial cooling in patients undergoing myocardial revascularization.

The effect of intracoronary administration of nitroglycerin on the distribution of cardioplegia and myocardial cooling was assessed in 45 patients undergoing elective myocardial revascularization. The patients were divided into three groups. Myocardial temperature was measured over the right and left coronary artery distributions in Group 1 after the infusion of 1 liter of potassium blood cardioplegic solution (20 mEq of potassium per liter). Similar temperature measurements were made in Group 2 after the addition of 300 micrograms of nitroglycerin to the cardioplegic solution and in Group 3 after the addition of 1,000 micrograms of nitroglycerin. Nitroglycerin did not affect myocardial cooling, and large temperature gradients persisted after delivery of cardioplegia in patients with occlusive coronary artery disease. Unexpectedly, however, the rate of cardioplegia delivery increased by 134%, within the same range of infusion pressures, in patients receiving nitroglycerin. Although nitroglycerin cardioplegia does not affect the regional disparity in the distribution of cardioplegia in patients with severe coronary artery disease, intracoronary administration of nitroglycerin reduces the time required for administration of cardioplegia and thereby decreases the total ischemia time.

Coronary Disease↗
PubMed1982

Measurement of spinal cord ischemia during operations upon the thoracic aorta: initial clinical experience.

Paraplegia has been an unpredictable, devasting complication following operations upon the thoracoabdominal aorta for over 30 years. The frequency ranges from 0.5% with operations for coarctation to as high as 15% following surgery for thoracoabdominal aneurysms. Both uncertainty and controversy exist about the value of different protective methods during aortic crossclamping (AXC): heparinized shunts, partial bypass, and reimplantation of intercostal arteries. This report describes the authors' initial clinical experience with a highly sensitive indicator of spinal cord ischemia, somatosensory evoked potentials (SEP) in an attempt to prevent paraplegia associated with surgical procedures on the thoracoabdominal aorta. Seven consecutive patients (one coarctation, five thoracic aneurysms, one thoracoabdominal aneurysm) underwent continuous operative monitoring of SEP. Cortical response to simultaneous electrical stimulation (20 mAmps, 0.6 mSec., 2.3 cps) of both the right and left posterior tibial nerves was recorded before, during, and after AXC, and following operation. When ischemic changes were detected by SEP, increasing distal circulation by different maneuvers (heparinized shunt, femoral-femoral bypass, reimplantation of intercostal arteries) reversed these changes. In two patients with thoracic aneurysms, ischemic changes appeared within three minutes after AXC and all potentials disappeared in nine minutes. Rapid insertion of a graft (AXC 28 and 37 minutes) resulted in SEP return 40 minutes following restoration of flow. These changes were prevented by a heparinized shunt in two patients, femoral/femoral bypass in one, and T8-T9 intercostal reimplantation in one. No SEP changes occurred in the patient with coarctation. No postoperative neurologic complications occurred. Continuous operative monitoring of SEP has exciting possibilities for preventing paraplegia. It is simple, highly sensitive, and seems to provide a precise measurement of adequacy of circulation to the spinal cord.

Adolescent↗