Biomedical subjects
Publications and source records attributed to D M Shah.
The incidence of monozygotic twins with trisomy 18 is 1 in 1,000,000 births. We report a case diagnosed prenatally with lymphocyte culture from fetal blood samples obtained by cordocentesis. Fetal growth lag and structural malformations detected by ultrasonography indicated chromosomal abnormality. A saline solution infusion technique ensured that cordocentesis obtained a sample from each twin.
We present three cases with abnormal fetal heart rate patterns and cordocentesis umbilical venous blood gas analyses. Conflicting heart rate patterns and cordocentesis and postnatal blood gas analyses prompt questions with regard to abnormal fetal heart rate pattern interpretation and suggest that cordocentesis blood gas analysis aids perinatal management only as a reflection of fetal status at sampling time.
We retrospectively studied 48 pairs of twin gestations delivered between 24 and 28 weeks' gestation from 1975 to 1986 at Vanderbilt University Medical Center. The incidence of fetofetal transfusion syndrome was 20%, more than double the incidence previously reported in large series of twin deliveries that encompassed a wider gestational age range. The overall mortality was 55%, and mortality for the fetofetal transfusion group was 70%, whereas a subset of the fetofetal transfusion group, those without weight discordancy, had a mortality rate of 75%. Our findings suggest that traditional reliance on ultrasonographic criteria for diagnosis of fetofetal transfusion will not detect 40% of such cases. The poor outcome data suggest a need for innovative approaches to diagnosis and treatment.
Retroperitoneal exposure of the abdominal aorta is usually performed through a left flank incision. An alternative approach to the abdominal aorta is described utilizing a right flank incision. Indications for the use of the right retroperitoneal approach during surgery for aortic aneurysms include right renal artery stenosis, right iliac artery aneurysm, need for simultaneous cholecystectomy, multiple or recent intraabdominal procedures, and sigmoid colostomy. A series of 17 patients is presented to illustrate the utility of this approach. There was one operative death in an emergent patient; the cause of death was not related to the method of aortic exposure. The remaining patients recovered quickly. The anatomic advantages and limitations of this exposure are discussed. We believe that retroperitoneal aortic exposure is superior to midline transperitoneal exposure. Aortic exposure utilizing a right retroperitoneal approach is a useful option in the surgical armamentarium.
In the carotid system with relatively constant blood flow, peak systolic velocity within a stenosis (PSVST) can characterize the degree of hemodynamic stenosis. We have studied flow/velocity characteristics in an in vitro model of stenosis within conduits of varying diameters in an attempt to quantify the degree of stenosis from flow/velocity profiles in peripheral vein bypasses. A Harvard pulsatile flow pump (70 BPM) pumped human blood (HCT, 35-45%) through thin-walled polytetrafluoroethylene (3-6 mm in i.d.) into a variable peripheral resistance maintaining a constant mean blood pressure of 80 mm Hg over a flow range of 0-500 ml/min. A Diasonics DRF400 duplex scanner with a 10-MHz imager and 4.5-MHz Doppler probe was used to image and Doppler the conduits and measure flow through them. Validation of Doppler flow measurements (DF) was performed comparing them with flow measured (MF) by timed collection. PSVST within and pressure drop across a 50% stenosis was measured for each of the conduit's sizes over a range of 0-500 ml/min MF. The results show a good correlation between DF and MF (r = 0.99, P less than 0.001) for the whole range of internal diameters. In each 50% stenosed conduit, PSVST correlated well with MF (r = 0.95, P less than 0.001). Curves were constructed of MF vs PSVST for each 50% stenosed conduit. We conclude that measurement of volumetric flow, conduit diameter, and peak systolic velocity within a vein bypass can objectively predict bypass stenoses of 50% or greater.
A modified scheme for biophysical profile scoring based exclusively on real-time ultrasonographic examination is proposed and includes expanded scores of fetal movements and fetal breathing and only qualitative assessment of accelerated placental maturation, subjective ultrasonographic impression of oligohydramnios, and decreased fetal tone. This method was compared with the method of Vintzileos et al. in the first phase of this observational study and was found to have good correlation in different score categories. This method was then applied in the second phase of the study to 180 high-risk pregnancies to examine correlation with perinatal outcome variables. The relationship between results of the last total score and perinatal outcome variables shows good predictive values. Results of this preliminary study suggest that real-time ultrasonographic evaluation-based scoring of acute fetal events, namely, movements and breathing alone, may have an important role in perinatal management.
The anatomical location of the saphenous vein in the distal thigh allows for construction of an in situ bypass to the above-knee popliteal artery. The authors have performed over 1400 in situ bypasses in the past 10 years. Forty-three of these have been to the above-knee popliteal artery. Thirty-three bypasses were performed for limb threatening ischemia, seven for disabling claudication and three for microemboli. Mean patient age was 67 years, 51% were males, 44% had diabetes mellitus, and 93% smoked. Grafts were followed from one to 108 months. The cumulative patency rate at two years was 90% and at four years 77%. Patency rates compare favorably to those of femoral-to-above-knee popliteal bypasses constructed using reversed saphenous vein or polytetrafluoroethylene. The authors found that the in situ femoral-to-above-knee popliteal bypass is a technically easy procedure requiring short operative times and has a low morbidity rate. In those select patients in whom a femoral-to-above-knee bypass is the procedure of choice the in situ bypass should be considered.
Sonography has a major role in the identification, evaluation, and treatment of the hydropic fetus. Although the prognosis of the NIH fetus is generally poor, the IIH fetus can frequently be treated effectively by transfusions performed by percutaneous needling of the umbilical vein. In addition, sonographic guidance of percutaneous umbilical vein sampling affords an accurate assessment of the etiology of NIH by facilitating karyotyping of the fetal blood.
Transabdominal aortic replacement is the most widely accepted surgical approach in the treatment of infrarenal abdominal aortic aneurysms (AAA) with an enviable mortality rate of 2 to 5 per cent. This approach, however, is attended by significant intraoperative loss of fluid and subsequent translocation as well as impaired postoperative pulmonary function and ileus. Although the retroperitoneal exposure of the aorta was used for the first repair of an AAA by Dubost and has been championed more recently by others, it has not been widely accepted. Experience suggests, however, that the exposure is as good and that postoperative morbidity is significantly less than that with the transperitoneal approach. In the past five years, we have surgically treated 299 AAA, 106 by the transabdominal route and 193 by the extended retroperitoneal approach. In 133 of the 193 patients upon whom the retroperitoneal approach was used, the aneurysm was left intact after division of the infrarenal aorta for an end to end proximal anastomosis of an aortoaortic to iliac to femoral bypass. There has been a significant reduction in the intraoperative replacement of fluid and blood, in postoperative respiratory support, in length of time in the intensive care unit and in occurrence of postoperative ileus when compared with the transabdominal endoaneurysmorrhaphy approach. Furthermore, the exposure, particularly upon the obese patient, is superior. Findings from this experience using the retroperitoneal approach for repair of AAA indicate that it results in less over-all physiologic disturbance of the patient.
5-Enolpyruvylshikimate-3-phosphate (EPSP) synthase is an enzyme of the shikimate pathway which is located in the chloroplasts in higher plants. This enzyme is the target of the nonselective herbicide glyphosate. We have isolated and sequenced cDNA clones encoding EPSP synthase from petunia and tomato. The deduced amino acid sequences of the two enzyme precursors show 93% identity in the mature protein regions and 58% identity in the transit peptides. The sequences of the plant enzymes show significantly greater similarity to bacterial EPSP synthases than to fungal EPSP synthases. A genomic clone containing an EPSP synthase gene was isolated from a library of petunia DNA and was shown to contain seven intervening sequences. This gene is expressed approximately 25-fold higher in flower petals than in other organs of petunia. Transcription of this gene is initiated at multiple sites in petunia leaves and in a glyphosate-tolerant petunia cell line overproducing EPSP synthase mRNA. In petals, however, transcription of this gene is initiated almost entirely from only one of these sites. In contrast to petunia, the levels of EPSP synthase mRNA in different organs of tomato do not differ significantly.
Emergency surgery is the only effective treatment of ruptured abdominal aortic aneurysms, even though morbidity and mortality rates remain high. We have studied the feasibility of left retroperitoneal aortic exposure in these cases in an effort to reduce postoperative complications. Over a 33 month period, 29 patients underwent emergency surgery for either a ruptured or symptomatic infrarenal abdominal aortic aneurysm. Of 13 patients with ruptured aneurysms, 4 underwent repair through a midline transperitoneal approach (3 deaths) whereas the remaining 9 were repaired through the retroperitoneal exposure (1 death). Supraceliac aortic clamping through the same incision prior to aneurysm exposure maintained hemodynamic integrity. The remaining 16 patients with symptomatic aneurysms were all treated through the retroperitoneal exposure (3 deaths). In the retroperitoneal groups, the cause of death was cardiac in two patients, hypertensive stroke in one, and necrotizing pancreatitis in one. Morbidity consisted of prolonged intubation, respiratory distress syndrome, and thrombophlebitis in one patient each and acute tubular necrosis in two patients. We believe that the left retroperitoneal approach is a useful option in the emergent treatment of abdominal aortic aneurysms.
Infrapopliteal bypass in diabetic patients has been associated with lower rates of patency and limb salvage than in nondiabetic patients. We prospectively compared the patency and limb salvage rates of in situ tibial artery bypass in diabetic and nondiabetic patients. Of 681 in situ bypasses performed for limb salvage over a 7 year period, 387 (57 percent) were carried out in diabetic patients and 294 (43 percent), in nondiabetic patients. Indications for operation most commonly included gangrene or ulceration (74 percent of the diabetic group and 49 percent of the nondiabetic group). Otherwise, the two patient groups were similar. Cumulative patency rates at 1 and 5 years were similar (91 and 74 percent for diabetic patients and 90 and 76 percent for nondiabetic patients, respectively). Limb salvage rates were also not significantly different (96 and 86 percent at 1 and 5 years, respectively, for diabetic patients and 99 and 94 percent, respectively for nondiabetic patients). Despite the unfavorable pattern of atherosclerosis in diabetic patients, the results of tibial arterial reconstructions showed patency and limb salvage rates similar to those seen in nondiabetic patients.
The Warren shunt, despite its recognized attributes, has several major obstacles to gaining widespread acceptance in the surgical community. These include its technical difficulty and the increased incidence of postoperative ascites. We have begun using a retroperitoneal approach for the performance of this procedure, which we believe is technically easier and may lessen postoperative ascites. In addition, blood loss, the need for ventilatory support and intensive care, and the occurrence of postoperative ileus have all been reduced in our experience. Herein, we have reported the details of this approach and discussed its major advantages over the classic transperitoneal approach to the distal splenorenal shunt.
After sustaining blunt abdominal trauma, two patients were found to have intimal flaps in extrahilar renal arteries without thrombosis. These renal artery injuries were observed without surgical repair because of severe concomitant multiple organ trauma. Continued patency of the renal arteries was confirmed by sequential renal scans or arteriograms. To decrease the risk of morbidity and death after blunt renovascular trauma, a patent artery with an intimal flap may be observed. Mandatory urgent repair is reserved for patients with bilateral renal injuries or for patients with a solitary kidney. Should symptomatic renal infarction or hypertension develop, delayed renal artery repair or nephrectomy is indicated.
Distal bypasses for the terminal stages of atherosclerotic occlusive disease manifest by chronic limb-threatening ischemia are among the most challenging arterial reconstructive procedures of surgeons today. The length and low flow rates of distal bypasses often exceed the functional limits of synthetic and even free vein grafts. However, the saphenous vein, when used in situ, provides a unique, viable, physiologically active, and hence antithrombogenic endothelial flow surface that is ideally suited for such bypasses. This paper presents the experience of the Albany Medical Center Hospital with the first 1000 in situ bypasses performed by the valve incision method over a 12-year period. Limb-threatening ischemia was the most common indication for surgery (91%). An in situ bypass was attempted in over 95% of unselected limbs and were completed in situ and in toto in 94%. 66% of the bypasses were carried out to the infrapopliteal level, and in more than 50% of the limbs, the distal vein diameter was less than 3.5 mm. The 30-day patency rate was 95%, and the cumulative patency rates, by life table analysis at 1, 2, 3, 4, and 5 years, were 90%, 86%, 84%, 80%, and 76%, respectively. The vein diameter, specific outflow vessel, level of distal anastomosis (length of bypass), inguinal inflow source used, and instrumental evolution had no significant effect on immediate or long-term bypass performance.
In an attempt to define optimal management, we have studied the outcome of 29 isolated tibial arterial injuries during the past 4 years. Twenty-five patients suffered blunt and four had penetrating trauma. Twenty-seven patients had preoperative arteriography which showed at least one interrupted tibial artery. In nine patients, immediate and successful reconstruction was done. Since the foot was viable in 20 patients, immediate reconstruction was not carried out in spite of the diagnosis of tibial arterial injury. Three of 20 underwent primary amputation. Fifteen of the remaining 17 patients required further angiographic evaluation for arterial reconstructions 2 to 12 months later for nonhealing of wounds, malunion of fractures, and soft-tissue defects. Delayed reconstructions were generally more complex. In 13 patients both viable and functional feet were eventually achieved. Bypass with autogenous vein was mandatory for success. Our experience has shown that most tibial arterial trauma will require immediate repair for success. Delayed repair was more difficult and was associated with substantial limb loss.
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This report documents the outcome of 25 pregnancies with elevated serum alpha-fetoprotein levels on two separate samplings despite normal anatomic appearance of the fetus on a detailed "consultative" sonographic examination. Six of these also had elevated amniotic fluid alpha-fetoprotein. All fetuses in this series were anatomically normal at time of delivery; one aborted fetus was triploid. Of the 25 pregnancies, 16 had sonographically demonstrable placental hemorrhage, eight retroplacental and eight subchorionic. One had hydropic changes in the placenta associated with triploidy. Of the subgroup of six pregnancies in which both serum and amniotic fluid values were elevated, one had a retroplacental hemorrhage, one had a subchorionic hemorrhage, and one had diffuse hydropic changes in the placenta. A control group of 112 patients with normal alpha-fetoprotein levels yielded four with small (less than 2 cm3) subchorionic hemorrhage. The occurrence rate of placental hemorrhage in women with elevated alpha-fetoprotein and normal fetus was 64%, whereas the control group of patients with normal alpha-fetoprotein had a 3.6% occurrence rate of placental hemorrhage. Sonographically detectable placental abnormalities may be associated with elevated alpha-fetoprotein in serum and/or amniotic fluid samples. Such abnormalities may occur because of fetomaternal admixture associated with placental hemorrhage and/or intraamniotic bleeding resulting from subchorionic hemorrhage.