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Biomedical subjects

V Falk

Publications and source records attributed to V Falk.

At least 19 recordsLinked to original sources
PubMed1998

Control of endoaortic clamp position during Port-Access mitral valve operations using transcranial Doppler echography.

The technique of computer-aided transcranial Doppler echography for continuous control of cerebral perfusion during minimally invasive mitral valve operations using the Port-Access system is described. Temporary displacement of the endoclamp in the aortic arch (brachiocephalic trunk, left carotid artery) is followed by cerebral embolic signals and a sudden decrease in the blood flow velocity in the middle cerebral arteries.

Aorta↗
PubMed1998

Minimally invasive port-access mitral valve surgery.

OBJECTIVES: This study evaluates the feasibility of video-assisted minimally invasive mitral valve surgery by means of the Port-Access system. The aim of the study was to minimize surgical access and to develop a video-assisted surgical technique. METHODS: The Port-Access system allows for closed chest endoluminal aortic clamping, cardioplegic arrest, and decompression of the heart. The mitral valve was either repaired (n = 28) or replaced (n = 23) in 51 patients by means of a minimally invasive approach through a right lateral minithoracotomy and under videoscopic guidance. RESULTS: Mean length of incision was 5.4 +/- 1.8 cm (range 3.8 to 8 cm). Mean duration of operation, cardiopulmonary bypass, and crossclamp time was 196 +/- 53, 133 +/- 52, and 72 +/- 27 minutes, respectively. Median intubation time was 25.5 hours (range 5 to 264 hours). Median duration of intensive care and hospital stay was 2 days (range 1 to 36 days) and 13 days (10 to 36 days), respectively. Hospital mortality was 9.8% (5/51). Overall morbidity was relatively high. In two patients acute retrograde aortic dissection led to conversion of the procedure. At follow-up (261 +/- 13 days), three patients required reoperation for paravalvular leakage. Baseline mean Duke activity index score was 19.3 +/- 11.3 before the operation and increased to 23.2 +/- 10 at 6 weeks' and 24.2 +/- 10.3 at 12 weeks' follow-up, respectively. CONCLUSION: The Port-Access system allows for video-assisted minimally invasive replacement and complex repair of the mitral valve through a right lateral minithoracotomy. However, morbidity and mortality associated with this novel technique were high.

Aged↗
PubMed1998

Conversion of complex neonatal Ebstein's anomaly into functional tricuspid or pulmonary atresia.

BACKGROUND: Ebstein's anomaly, due to failure of delamination of one or more leaflets of the tricuspid valve (TV), is associated with varying degrees of tricuspid regurgitation (TR) and dysplasia of the right ventricle (RV). Although refinement of tricuspid valvuloplasty and plication techniques have opened the way to a satisfactory outlook for the majority of older children and adults, Ebstein's anomaly presenting at neonatal age, secondary to ineffective forward flow into the pulmonary and systemic circulation, has a reported mortality rate of as high as 75%. In order to improve the dismal outcome in neonatal Ebstein's anomaly, we have strived for early univentricular palliation. PATIENTS AND METHODS: Univentricular repair was performed in five neonates (median age 5 days; range 2-14 days) with Ebstein's anomaly, ductal dependent pulmonary blood flow, severe TR, absence of forward flow across the pulmonary valve, and small left ventricular (LV) area due to right-to-left bowing of the ventricular septum and ineffective LV loading (median indexed LV area 10.5 cm2/m2). In addition, two neonates had moderate pulmonary regurgitation (PR), one with additional pulmonary stenosis. In all patients, the indexed area of the combined right atrium and atrialized RV was greater than that of the combined functional RV, left atrium, and left ventricle (median 22.0 and 20.8 cm2/m2, respectively). The median preoperative systemic oxygen tension was 35 mmHg and the median pH 7.28. Repair consisted of TV closure with a pericardial patch (with the coronary sinus draining into the RV) (n = 3) or, in the presence of PR, resection of the dysplastic TV and division and oversewing of the main pulmonary artery (n = 2), as well as excision of the atrial septum, resection of redundant right atrial wall, and construction of an aortopulmonary shunt (n = 5). RESULTS: The median indexed LV area increased from 10.5 to 18.8 cm2/m2 as a result of more effective loading of the left ventricle. There was no intraoperative or late mortality. The patients were extubated at a median of 7 days postoperatively. At discharge, the median systemic oxygen tension was 46 mmHg. In all five patients, at 6, 7, 10, 12 and 16 weeks of age, a bidirectional cavopulmonary anastomosis has been constructed. CONCLUSIONS: In neonates with Ebstein's anomaly and ductal dependent pulmonary blood flow, rational palliation consists of the surgical creation of tricuspid atresia or, in the additional presence of PR or pulmonary stenosis, the creation of pulmonary atresia. These procedures may result in effective LV decompression and more effective volume loading of the left ventricle with increase of systemic output and improved clinical outcome.

Aorta↗
PubMed1998

An experimental approach to quantitative thermal coronary angiography.

Thermal coronary angiography is a noninvasive but not yet quantitative method to intraoperatively assess graft patency in CABG surgery. Aim of this study was to quantify graft flow by measuring perfusion-induced myocardial temperature changes over time. Saphenous vein grafts to the left anterior descending artery were perfused at flow rates of 16-105 ml/min with warm saline. A thermal scanner with a 256 x 256 focal-plane array detector providing a spatial resolution of 1.2 mrad was used. The resulting temperature curves were averaged and a non-linear fit procedure was performed to calculate the time constant (tau) at each flow rate. An increase of myocardial temperature along the LAD with different flow rates could be demonstrated. There was an excellent correlation between the calculated time constant and actual flow (r = 0.96, p < 0.0002). By determining the time constant for different flow rates an estimate of actual graft flow is possible using thermal coronary angiography. Clinical studies have to show if the time constant can be used as a predictor of graft flow in patients.

Animals↗
PubMed1997

Low-grade intimal hyperplasia in internal mammary and right gastroepiploic arteries as bypass grafts.

BACKGROUND: Knowledge is limited regarding the histology of the internal and right gastroepiploic arteries that have been functioning as coronary artery bypass conduits. METHODS: Four internal mammary arteries, 3 right gastroepiploic arteries, and 1 saphenous vein graft that had been functioning as coronary artery bypass grafts were harvested and examined histologically in 3 male patients who had died at 19, 38, and 47 months after coronary revascularization. RESULTS: All grafts were patent. The mean thicknesses of the intima in the proximal, middle, and distal segments were 41.0, 31.8, and 25.8 microns for the internal mammary artery and 58.0, 40.3, and 34.3 microns for the right gastroepiploic artery. The saphenous vein graft showed severe focal atherosclerosis. CONCLUSIONS: This histologic study in a small number of patients corroborates the reported excellent patency rates at medium- to long-term follow-up of the internal mammary and right gastroepiploic arteries used as coronary artery bypass grafts.

Aged↗
PubMed1997

Morphometric study of the right gastroepiploic and inferior epigastric arteries.

BACKGROUND: Based on earlier observations that the thickness of the intima and structure of the media may have an impact on the long-term patency of arterial conduits and the lack of detailed histologic studies of the right gastroepiploic and inferior epigastric arteries, we subjected both vessels to morphometric analysis with emphasis on their suitability as conduits in myocardial revascularization. METHODS: The right gastroepiploic and inferior epigastric arteries were harvested from 28 unselected individuals (mean age, 73.2 years) at autopsy, and the luminal diameter and the width of the intima and media were measured. RESULTS: At all levels of measurement (origin, 10 cm, and 15 cm), the luminal diameter of the inferior epigastric artery was significantly smaller than that of the right gastroepiploic artery (p < 0.05). The right gastroepiploic artery demonstrated only mild intimal hyperplasia. In contrast, the inferior epigastric artery showed substantial intimal hyperplasia within the first 1-cm segment (mean, 134 +/- 131 microns versus 50 +/- 49 microns for the corresponding segment of the right gastroepiploic artery; p = 0.01). Intimal hyperplasia was only mild in the remainder of the inferior epigastric artery. In both vessels, the media was muscular with rare dispersed elastic fibers. The mean thickness of the media ranged from 380 +/- 116 microns proximally to 155 +/- 70 microns distally for the right gastroepiploic artery, and from 316 +/- 86 to 165 +/- 70 microns, respectively, for the inferior epigastric artery. CONCLUSIONS: In myocardial revascularization, use of the right gastroepiploic artery may generally be preferable to use of the inferior epigastric artery. This recommendation is based on the larger luminal diameter of the right gastroepiploic artery as compared with the inferior epigastric artery, the significantly greater intimal hyperplasia in the first segment of the inferior epigastric artery, and the limitation that the inferior epigastric artery can be used only as a free graft. The rate of development of intimal hyperplasia in the right gastroepiploic artery, if used as an in situ coronary artery bypass graft, may be slow, approximating that of the right gastroepiploic artery in its natural environment.

Aged↗
PubMed1997

Thermal coronary angiography for intraoperative testing of coronary patency in congenital heart defects.

Intraoperative thermal coronary angiography was successfully applied in 9 patients who underwent operative correction of congenital heart defects: arterial switch operation for transposition of the great arteries (n = 5), Ross operation for valvar aortic stenosis with regurgitation (n = 3), and aortic implantation of the left coronary artery for anomalous connection of the left coronary artery to the pulmonary artery (n = 1). Intraoperative thermal coronary angiography allows early detection and surgical correction of coronary ostial obstruction.

Coronary Angiography↗
PubMed1997

Instantaneous subaortic outflow obstruction after volume reduction in hearts with univentricular atrioventricular connection and discordant ventriculoarterial connection.

OBJECTIVE: To study the phenomenon of potential subaortic outflow obstruction after surgical volume unloading of the heart in patients with univentricular atrioventricular connection, discordant ventriculoarterial connection, and bulboventricular foramen (BVF)-dependent systemic flow. MATERIAL AND METHODS: Intraoperative transesophageal echocardiography was used in five patients with tricuspid atresia (N = 3) or double-inlet left ventricle (N = 2) with rudimentary right ventricle and BVF who were scheduled to undergo a bidirectional cavopulmonary anastomosis (N = 3) or completion of the Fontan procedure after previous banding of the pulmonary artery (N = 2). The BVF diameter was measured in two orthogonal views, and the area was calculated by using the formula for an ellipse. Left ventricular posterior wall thickness and left ventricular internal diameter were also measured. Intraoperative prerepair and postrepair gradients across the BVF were measured by echocardiography. RESULTS: Volume unloading of the left ventricle resulted in instantaneous contraction of left ventricular size (decrease of median left ventricular internal diameter from 38 to 34 mm and increase of median left ventricular posterior wall thickness from 5 to 7 mm), decrease of median BVF area index (from 1.82 to 1.55 cm2/m2), and development of a median gradient of 60 mm Hg across the BVF. At a mean follow-up of 19.6 months, all patients were clinically well and had no echocardiographic evidence of BVF obstruction. CONCLUSION: In hearts with univentricular atrioventricular connection, discordant ventriculoarterial connection, and BVF-dependent systemic flow, a decrease in ventricular volume is associated with an instantaneous alteration in ventricular geometry, diminution in BVF size, and potential for subaortic outflow obstruction. Intraoperative transesophageal echocardiography is of paramount importance in excluding development of subaortic outflow obstruction in this setting.

Anastomosis, Surgical↗
PubMed1997

Repair of subaortic stenosis in atrioventricular canal with absent or restrictive interventricular communication by patch augmentation of ventricular septum, resuspension of atrioventricular valves, and septal myectomy.

OBJECTIVE: To describe a modification of a surgical technique for relief of subaortic stenosis in patients with atrioventricular canal. MATERIAL AND METHODS: We report an etiology-oriented modified technique of repair of subaortic stenosis after previous repair of atrioventricular canal, without (N = 2) or with (N = 1) a restrictive interventricular communication. RESULTS: In addition to a generous myectomy of the left ventricular septum, the technique consists of complete detachment of the left and right atrioventricular valves from the ventricular crest, patch augmentation of the concavity of the ventricular crest, and attachment of both atrioventricular valves at the superior aspect of the ventricular septal patch; thus, the septal leaflet of the left atrioventricular valve--in particular, its superior component--is lifted away from the elongated left ventricular outflow tract. CONCLUSION: This modification (as opposed to detachment of only the superior component of the septal leaflet of the left atrioventricular valve, as performed in previously proposed techniques) may be a valuable adjunctive technique to relieve subaortic obstruction associated with atrioventricular canal. In addition, this modification allows a secure anchoring of the patch to the right of the ventricular septum and therefore is associated with minimal risk of damaging the conduction tissue and of causing regurgitation of the left atrioventricular valve.

Aortic Valve Stenosis↗
PubMed1997

Stentless valve replacement in the small aortic root.

Despite the variety of different artificial heart valves available, no ideal prosthesis for the small aortic root has yet been identified. The aim of this study was to evaluate the haemodynamic performance and clinical outcome after stentless aortic valve replacement. A total of 70 patients with a small aortic root underwent Toronto (n = 61) or Freestyle (n = 9) stentless aortic valve replacement. All but three patients had aortic stenosis. Mean (s.d.) age at operation was 71.2(7.9) years. The mean annular diameter was 21.4(1.2) mm. Using controlled oversizing adjusting valve size to the sinotubular junction diameter, a 23-mm prosthesis was implanted in 23 patients and a 25-mm prosthesis in 47 patients. The maximum pressure gradient was 19.1(6.8) mmHg and effective valve orifice area was 1.47(0.27) cm2. At discharge and at follow-up, all patients were in New York Heart Association class I or II. At follow-up there was a significant reduction in pressure gradients, an increase in effective valve orifice areas, and decrease of pre-existing left ventricular hypertrophy. In conclusion, with controlled oversizing a gain in prosthesis size of 2 to 4 mm can be achieved. Implantation of oversized stentless valves leads to improved haemodynamics and to left ventricular remodelling in patients with a small aortic root.

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