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Biomedical subjects

D M Shah

Publications and source records attributed to D M Shah.

261 records · Page 15Linked to original sources
PubMedDate not supplied

In situ bypass hemodynamics. The effect of residual A-V fistulae.

The effect of arteriovenous fistulae on in situ saphenous vein bypass hemodynamics and patency rates has been of great concern to some. It is our practice to ligate only those fistulae which conduct enough dye upon completion angiography to visualize the deep femoral venous system. We have prospectively studied 216 such bypasses using duplex ultrasound scanning to assess overall hemodynamic function over periods from 1 to 156 months postoperatively. Volumetric blood flow was measured in proximal and distal portions of the bypass choosing a region of uniform diameter with laminar flow. Mean fistula flow was derived by subtracting distal bypass flow from proximal bypass flow. Distal flow decreased significantly (p less than 0.01 paired t-test) from 68 +/- 4.6 ml/min (mean +/- SEM) at 2 months postoperatively to 51 +/- 4.8 ml/min at 12 months postoperatively. There was an overall decrease in fistula flow from 256 +/- 26.9 ml/min at 2 months to 86 +/- 22.6 ml/min at 12 months. In 14 of the 216 bypasses (6.5%), arteriovenous fistulae were ligated during the first postoperative year. This was necessitated by persistent increased fistula flow with or without edema and indication from PVR or segmental pressure of decreased resting flow or pressure. Following fistula ligation, fistula flow decreased and distal bypass flow improved. Within this select group of patients with reduced flow capacity, i.e., a proximal stenosis or small vein size, high fistula flow is poorly tolerated with a significant redistribution of flow resulting in reduced distal perfusion. However, for the majority of patients (95%), fistula flow does not deleteriously affect distal bypass flow.

Arteriovenous Shunt, Surgical↗
PubMedDate not supplied

The fate of extremities with flat lower calf pulse volume recordings.

The prognosis of patients with a flat (Class 5) or nearly flat (Class 4) pulse volume recording was studied in relation to the signs and symptoms of vascular disease in 517 patients. Within one year of follow up, 97.9% of 96 patients with jeopardized limbs and flat tracings required surgery, whereas 72.4% of 29 patients with no or minimal symptoms required reconstruction (p less than 0.001); 85.7% of patients with Class 4 tracings and jeopardized limbs required surgery, whereas 41.9% of those with minimal symptoms and Class 4 recordings developed need for reconstruction (p less than 0.001). The requirement for surgery Class 5 patients is significantly higher than in those with Class 4 tracings. The general trend of pulse volume recording amplitude to correlate with ankle systolic blood pressure was confirmed. One year mortality in Class 5 patients was 43.2%. The majority of patients with severely abnormal pulse volume recordings eventually come to surgical reconstruction. The timing of surgery is based on the clinical status of the jeopardized limb, not solely on the presence of a pulse volume tracing abnormality.

Blood Pressure↗
PubMedDate not supplied

Sartorius muscle coverage for the treatment of complicated vascular surgical wounds.

Sartorius muscle flaps were evaluated in 14 patients treated for complicated groin wounds related to vascular surgical procedures. Particular risk factors for poor wound healing were present in 8 patients, including diabetes, obesity, or poor nutrition in 3 patients; prior radiotherapy to the groin in 2; reoperative groin exposure in 3. Eleven of 14 patients had multiple indications for sartorius flap coverage, including hemorrhage in 5 patients, groin wound sepsis in 3, graft sepsis in 2, wound necrosis in 5, exposure of a reconstruction in 4, treatment of a lymphocele in 1, and treatment of groin irradiation in 2. Nine flaps were proximal sartorius segments rotated into the groin, four were distal muscle reflected into the groin, and one was a mobilized mid-portion of the muscle. Early successful wound healing occurred in all patients, but complications included muscle bed infection in 1 patient, late recurrence of lymphocele in 1, and recurrent groin sepsis in 1. Hemorrhage did not recur, and existing reconstructions were salvaged in all patients. The sartorius flap is a well-tolerated method for achieving autogenous tissue coverage for the problem groin wound, and there is no long-term functional deficit from anatomic loss of the sartorius muscle.

Groin↗
PubMedDate not supplied

Comparison between selective distal splenorenal shunt and small diameter H-graft portosystemic shunt.

Although most commonly performed portal decompressive procedures control bleeding effectively, postoperative morbidity and mortality remains a serious problem in these patients. Both distal splenorenal shunts (DSRS) and small-diameter portacaval H-grafts (PCHG) are reported to produce decreased rates of postoperative encephalopathy. We prospectively evaluated 69 patients in whom 27 PCHG and 45 DSRS were performed over a seven-year interval. There were no significant preoperative differences between these groups. Operative mortality was 12.9% overall. DSRS was associated with decreased intraoperative blood transfusions and operative time. Postoperatively, DSRS was associated with significantly less encephalopathy, other postoperative complications, and ascites. Recurrent variceal bleeding was seen in three patients treated with PCHG and two patients with DSRS. We conclude that both DSRS and PCHG are effective in preventing recurrent variceal bleeding, but DSRS remains our procedure of choice because of its decreased rates of postoperative complications.

Blood Vessel Prosthesis↗
PubMedDate not supplied

Intra-operative and post-operative flow in the in-situ saphenous vein bypass.

We have attempted to further define the hemodynamic properties of the arterialized in-situ saphenous vein. The natural taper of the vein and the presence of arteriovenous fistulas are two unique factors associated with this conduit. Utilizing intra-operative electromagnetic flowmeter (EF) measurements and post-operative duplex ultrasound scanning (DUS), we have studied the natural history of these conduits from the time of their arterialization. The EF mean arterial blood flow in 71 in-situ bypasses was 100.8 cc/ml, range 25-200. No significant correlation was found between these measurements and angiographic runoff, vein diameter, pre- or post-operative Ankle/Brachial Index (ABI) and site of distal anastomosis. Three immediate failures requiring revisions were not predicted by EF flow measurements. Using the unique combination of Doppler ultrasound measurement and real time imaging, afforded by the DUS, fistula flow was determined. These studies showed that terminal bypass segment blood flow is not significantly affected by cutaneous fistula interruption. We found that duplex ultrasound scanning is a useful tool ideally suited to the study of the arterialized saphenous vein in-situ. One of its main advantages is the ability to accurately localize the site and hemodynamic significance of any arteriovenous fistulas.

Angiography↗
PubMedDate not supplied

Evaluation of fiberoptic dermofluorometry as a means of clinically assessing tissue perfusion.

Fiberoptic dermofluorometry (FDF) transcutaneously measures fluorescence, following an intravenous injection of sodium fluorescein (NaFl), which is transmitted along a fiberoptic bundle to a photomultiplier tube and converted into dermofluorescence units (DFU). In five normal subjects studied, the plasma concentration of NaFl peaked at 5-15 minutes before decaying with first order kinetics and corresponding dermofluorescence (DF) rose to a peak between 10-20 minutes before decaying. Peak DF in the head and neck was significantly higher (P less than .001) compared to other skin sites which were similar. Application to patients (n = 16) undergoing successful lower limb revascularization showed a significant (P less than 0.01) improvement in perfusion at the foot level only. The reproducibility of FDF was poor when studied on the control limbs. We conclude that FDF does not, at present, constitute a valid measure of skin perfusion.

Adult↗
PubMedDate not supplied

Extraperitoneal aortic bypass with exclusion of the intact infra-renal aortic aneurysm: the in-situ management of aortic aneurysms. A preliminary report.

Transabdominal aortic aneurysmorraphy with graft replacement is the generally accepted and most widely applied surgical approach in the treatment of infra-renal abdominal aortic aneurysm with a mortality rate of 2-5%. The alternative, retroperitoneal exposure of the aorta, although utilized for the first reported repair of an AAA by Dubost and championed by Rob, Stipa and Shaw, Helsby and Moosa and more recently by Williams et al., offers superior exposure and decreased post-operative morbidity. Despite these advantages, it is not commonly used by most vascular surgeons for the surgical management of aortic aneurysms. We have treated 35 patients using an extended retroperitoneal approach in which the aneurysm was treated by division of the infra-renal aorta, an end-to-end proximal anastomosis with an aortic bypass, and over-sewing of the aneurysm. In this group of patients, we found less post-operative physiological disturbances and a reduced requirement for blood transfusion. These data suggest that this method of retroperitoneal exclusion and bypass is generally applicable and is of particular value in the obese and/or the higher risk, medically disadvantaged patient.

Aged↗
PubMedDate not supplied

Neonatal outcome of premature infants of mothers with preeclampsia.

Our objective was to compare the outcome of premature infants of mothers with preeclampsia and hypertension with properly matched controls to examine whether infants of mothers with preeclampsia are at a lesser risk. We designed a retrospective cohort study of 99 infants of mothers with preeclampsia and hypertension (IHM) at < or = 36 weeks' gestation. Infants of nonhypertensive women matched for gestational age, gender, asphyxia, maternal diabetes mellitus, twin gestation, and mode of delivery served as controls. Data were analyzed by dividing all cases into three gestational age groups: group I, 26 to 30 weeks' gestation (IHM n = 21, control n = 39); group II, 31 to 33 weeks (IHM n = 32, control n = 61); and group III, 34 to 36 weeks (IHM n = 46). Because detailed data on nonhypertensive infants at 34 to 36 weeks' gestation were available only for intensive care unit admissions, group III was excluded from the comparative analysis. The incidence of hyaline membrane disease was significantly lower in IHM compared with the controls in groups I and II (group I, 19.1% vs 46.2%, p < 0.005; group II, 12.5% vs 32.8%, p < 0.04). Symptomatic patent ductus arteriosus occurred less frequently in groups I and II compared with controls (group I, 28.6% vs 46.2%, p < 0.001; group II, 3.1% vs 13.1%, p < 0.005). Intraventricular hemorrhage was less frequent in group I compared with controls (4.8% vs 20.5%, p < 0.001). The incidence of intraventricular hemorrhage in group II was similar at 3.1% versus 1.6% for controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗