Biomedical subjects

S C Babu

Publications and source records attributed to S C Babu.

31 records · Page 2Linked to original sources

PubMed1987

Adequacy of central hemodynamics versus restoration of circulation in the survival of patients with acute aortic thrombosis.

Acute aortic thrombosis is an infrequent clinical occurrence, but when it does occur, it is a true cardiovascular catastrophe. Our experience with 34 patients over a 12 year period was reviewed and factors influencing outcome were analyzed. Seventeen women and 17 men had various clinical presentations, although 74 percent of the patients had the classic picture of ischemia. Preoperative assessment of left ventricular function was carried out in all but one patient with intraoperative and perioperative monitoring to guide therapy in addition to revascularization procedures. While extent of the preexisting disease and number of additional operations did influence the outcome, the predominant factor for survival was the left ventricular functional state perioperatively. Fifteen of the 16 patients with adequate left ventricular function survived, whereas 15 of the 17 patients with a failing myocardium died (88 percent). Extraanatomic operations are preferable in patients with demonstrated inadequate left ventricular function. Expeditious restoration of circulation alone does not ensure a favorable outcome. The key to successful therapy is understanding, preventing, and effectively treating the mechanical and metabolic dysfunction of the heart. Review of the literature on acute aortic thrombosis revealed only few isolated case reports except for a recent report of eight patients. Our report of 34 patients over a 12 year period represents the largest experience to date from a single institution. Detailed analysis of hemodynamic parameters and the significance of determination of left ventricular function has not been reported so far in this subset of critically ill patients.

Acute Disease↗

PubMed1987

PTFE graft treated with silver norfloxacin (AgNF): drug retention and resistance to bacterial challenge.

Norfloxacin (NF) and silver norfloxacin (AgNF) were used to coat polytetrafluoroethylene (PTFE) vascular prostheses by using triododecylmethylammonium chloride as a cationic surfactant. The relative retention of the drug on the graft after subjecting it to the biological environment for 3 weeks and antibacterial activity against coagulase-positive Staphylococcus aureus and Escherichia coli were determined. In addition, the ability of AgNF-coated PTFE grafts to sterilize perigraft tissue after mixed bacterial contamination was studied and compared with control PTFE grafts in 10 dogs. At the end of 21 days, 15 and 18% of AgNF were retained on the grafts tested in in vitro and in vivo experiments, respectively. During the same time AgNF-coated grafts from in vitro experiments exhibited significant antibacterial activity (25 mm zone of inhibition (z.i.)), but antibacterial activity was negligible (10 mm z.i.) in the grafts from in vivo experiments. NF retention on the grafts could not be determined because of spectral interference by blood. The antibacterial activity of NF-coated grafts significantly declined after 24 hr in in vivo experiments, hence further evaluation of NF-coated grafts was not done. Seven perigraft sites surrounding AgNF-coated grafts were sterile, but only one perigraft site surrounding control grafts was sterile (P less than 0.05). Cultures from six of nine perigraft infections surrounding control grafts yielded heavy bacterial growth. There was only one wound infection at the site of AgNF graft while there were seven severe wound infections at control graft sites. AgNF-coated grafts exhibited prolonged antibacterial activity compared to NF-coated grafts and offered significant protection against infection from local bacterial contamination.

Animals↗

PubMed1985

Coexisting carotid stenosis in patients undergoing cardiac surgery: indications and guidelines for simultaneous operations.

The coexistence of critical carotid stenosis with coronary artery or valvular heart disease occurs in a small percentage of patients requiring open heart surgical procedures. Recognition of such combined lesions by noninvasive carotid testing identifies patients at risk for neurologic events. Our experience with 62 patients having combined simultaneous carotid and cardiac operations among 2,400 open heart surgery patients was compared with the results in 110 patients with only carotid endarterectomy operations. The outcomes indicated that carotid endarterectomy can be performed simultaneously with open heart surgical procedures with morbidity and mortality rates similar to those of isolated cervical artery operations. Thus, patients with significant coexisting carotid artery disease defined with specific criteria and coronary artery disease need not be exposed to cerebral ischemic events or to myocardial infarctions that often accompany staged operations.

Carotid Artery Diseases↗

PubMed1985

Pseudoaneurysm of anterior tibial artery after occlusion from blunt trauma: nonoperative management.

The angiographic finding of occluded isolated tibial artery after blunt trauma to the leg generally is ignored. A case of pseudoaneurysm and arteriovenous fistula that evolved from an occluded anterior tibial artery is presented. The pathology was treated successfully by percutaneous transfemoral placement of Gianturco coils in the tibial artery proximal and distal to the aneurysm. The nonsurgical approach in this patient avoided the risks of anesthesia, blood loss associated with a surgical procedure, the dilemma of the surgical approach in the presence of medial and lateral fasciotomy wounds, and of contamination and destabilization of the comminuted tibia-fibular fractures. This report raises the question of the proper management and followup procedures of occlusions of noncritical arteries found on angiography immediately after trauma.

Adult↗

PubMed1983

Expanded microporous polytetrafluoroethylene (PTFE) grafts in contaminated wounds: experimental and clinical study.

Autogenous vein graft is regarded as an ideal arterial substitute for its long-term patency and relative resistance to infection. A clinical instance of life-threatening hemorrhage from an infected disrupted vein graft stimulated a study in dogs, comparing vein and PTFE graft performance in wounds contaminated with S. aureus and E. coli cultured from the patient's wound. Infective disruption of vein wall occurred in three of ten animals resulting in exsanguination and death. Host artery disruption at PTFE suture line occurred in one of ten animals. Thrombosis of graft and host artery in this animal precluded hemorrhage and death. This led to favorable clinical experiences with PTFE grafts in contaminated wounds of 22 trauma patients. It is concluded that PTFE is better assurance against disruption and hemorrhage than vein graft in contaminated, potentially infected sites. PTFE may be used preferentially as a vascular substitute in trauma patients provided that all traditional surgical safeguards and principles are followed.

Adult↗

PubMed1982

Unappreciated causes of ischemia in the leg.

Limb ischemia due to blunt trauma, dissecting hematoma, and cardiac dysfunction jeopardizes limbs and lives more than is generally appreciated. Delay in diagnosis after blunt trauma led to major amputation in 21 percent of our patients. Current principles avoid those hazards. Five patients presented with acute limb ischemia caused by dissecting hematoma of the aorta. Suspicion of that diagnosis is warranted in patients without a history of chronic vascular occlusive disease or cardiac disease, in young white males with Marfan characteristics, and in middle-aged hypertensive black males. Confirmation of the diagnosis requires urgent angiography. In selected cases, treatment with femorofemoral bypass will be limb- and life-saving. Ischemia due to low flow, which portends a dire prognosis, should be suspected in severely ill patients with a history of peripheral vascular disease. Analysis of cardiac and metabolic functions with the Automated Physiologic Profile system identified the cause of the low flow state in 10 patients, permitting precise management with specific therapy. A discernible improvement in circulatory status of the limb coincided with correction of the low flow states. Angiography and surgery were not necessary in 90 percent of this group, and should be avoided during low flow episodes.

Aortic Aneurysm↗

PubMed1980

Monitor-guided responses. Operability with safety is increased in patients with peripheral vascular diseases.

Poor cardiopulmonary reserve was demonstrated in a group of 75 elderly patients undergoing elective vascular reconstruction when cardiovascular hemodynamics were analyzed with the automated physiologic profile (APP) preoperatively. Only 25 patients (33.3%) had normal left ventricular function (LVF) and did not need any corrective therapy before surgery. Increment in preload was necessary in 20 patients (26.7%) to improve myocardial function; 30 patients (40%) revealed abnormal LVF and hence required pharmacologic modulation and preload adjustment, inotropic support, and afterload reduction to enhance the ventricular performance. Conventional methods of clinical evaluation did not reveal the degree of compromised ventricular function and potential high risk of surgical morbidity and mortality in many of these patients. The APP disclosed subtle and important physiologic aberrations indicating modification of anesthetic and operative procedures and precise modulation of physiologic factors. Optimization was achieved in all except two patients, and only one was denied the benefits of vascular reconstruction.

Aged↗

PubMed1980

Pathological fibrinolysis secondary to pseudoaneurysms.

Pathological fibrinolysis due to pseudoaneurysms was observed in a patient 4 years after aortobifemoral bypass graft. The patient presented with a pulsatile abdominal mass and ischemic changes in the legs. Excessive bleeding from venipuncture sites prompted coagulation screening, which disclosed rapid clot lysis, fibrin split products, and low fibrinogen suggestive of pathological fibrinolysis. Therapy with epsilon amino caproic acid (EACA, Amicar) controlled the coagulopathy, permitting angiography and operation. Resection of the pseudoaneurysms resulted in resolution of the abnormal fibrinolysis. Normally, there is a balance between coagulation and fibrinolysis protecting against excessive bleeding or clotting. Clot itself is a powerful stimulus for the activation of the fibrinolytic system, although many other factors have been shown to initiate and sustain the process. Fibrinolysis is pathological when the process becomes excessive or inappropriate. Plasminogen is activated to plasmin which digests fibrin. Both plasmin and fibrin split products inhibit polymerization of fibrin monomers (which is the final step in the coagulation cascade in the formation of a stable clot), resulting in an unstable clot which is rapidly lysed. To our knowledge such a coagulopathy has not been reported to be a complication of pseudoaneurysms.

Aminocaproic Acid↗

PubMedDate not supplied

The clinical utility of carotid duplex scanning.

We retrospectively compared the results of duplex scanning (DS) with contrast angiography (CAN) in the evaluation of 119 patients whose 238 carotid arteries were evaluated by both methods within a four-week period. The results of all patients were then categorized by two different definitions of severity of stenosis. Category A classified 1-29% stenosis as mild, 30-69% stenosis as moderate, and 70-99% diameter reduction as severe stenosis. Category B defined mild stenosis as 1-19% lumen diameter reduction, moderate as 20-49% stenosis, and severe as 50-99% stenosis. The findings by each classification were compared in 60 patients with hemispheric symptoms and in 59 patients with nonspecific symptoms. CAN was our "gold standard", and exhibited greater sensitivity, specificity, accuracy, and predictive values than DS. Carotid arteries with 70% stenosis were identified by DS with greater specificity, accuracy, and predictive values than were arteries with 50% stenoses. Only the sensitivity was comparable in categorizations A and B (80% and 83%). All parameters of measurement were superior in patients with hemispheric symptoms. DS alone cannot substitute for CAN in selecting patients for carotid endarterectomy because its error rate exceeded acceptable rates of complications for carotid artery surgery. The false positive rate of DS was 4%. DS failed to diagnose 7 of 19 carotid artery occlusions, 9 of 11 ulcerated plaques, 7 of 119 instances of aortic arch disease, and 13 cases of severe intracranial artery stenosis.

Blood Flow Velocity↗

PubMedDate not supplied

Causes of limb loss in civilian arterial injuries.

Progress in the management of complex vascular injuries of the extremities has not eliminated the necessity for amputation. An analysis of 100 consecutive patients treated at the Lincoln Medical and Mental Health Center during 1974-1980 disclosed that five amputations followed 24 instances of blunt trauma, but only one minor amputation of toes was required in 76 patients after repair of arterial injuries associated with penetrating wounds. Extensive skeletal, muscular and skin loss at the sites of blunt trauma precluded salvage of two limbs. Physicians' failure to suspect arterial injury on admission in three patients with blunt trauma caused delay in the diagnosis and management of occlusive arterial injury that ultimately led to three amputations. In contrast, limited soft tissue damage accompanying penetrating wounds and high index of suspicion resulted in expeditious repair, accounting for the minimal risk of limb loss. Amputation may be obligatory in the presence of extensive skeletal and soft tissue destruction. However, limb loss due to delay in diagnosis is preventable. In every instance of blunt trauma to extremities, we advocate the same suspicion of vascular injuries as in penetrating trauma, with early liberal use of angiography whenever pulses are not absolutely normal, and prompt revascularization of ischemic limbs.

Adult↗

PubMedDate not supplied

Changing patterns in civilian arterial injuries.

A critical review of 185 patients with 211 arterial injuries over an eleven year period was performed to recognize the changing patterns in clinical findings, management and results. A ten fold increase in multiple arterial injuries as well as higher incidence of associated venous and visceral injuries occurred during the last five years. Despite this, the incidence of hypotension on arrival at hospital was reduced by half due to rapid transportation and resuscitation during transit. Shock in patients with only extremity injuries heralded dual injuries (arterial and venous). Lateral repair of both arterial and venous injuries has given way to end to end anastomoses, vein grafts and patch grafts. A greater tendency to repair all major arteries, most minor arteries, more liberal use of heparin, fasciotomy, intraluminal shunts, repair of venous injuries and extra-anatomic bypass has been noted. Rapid patient retrieval, early resuscitation, improved recognition and management of arterial injuries has not lead to better limb salvage or survival. The apparent lack of benefit in limb salvage is probably due to the higher incidence of multiple arterial injuries and associated venous injuries as well as the willingness to attempt repair all major arterial injuries and reluctance to advise primary amputation. Early patient retrieval, rapid transportation and resuscitation during transit has increased the number of potentially unsalvageable patients (who would otherwise be declared dead on arrival) resulting in an unchanging mortality.

Accidents, Traffic↗

PubMedDate not supplied

Simultaneous bilateral carotid endarterectomy operations.

Clinical reasoning and sound physiologic data have been the bases for performing bilateral simultaneous carotid endarterectomy operations in 25 patients recently. The results have compared favorably with unilateral carotid endarterectomy operations in 100 patients over the same time span. Thus, there is ample basis for performing operations simultaneously when bilateral carotid endarterectomy operations are indicated.

Adult↗

PubMedDate not supplied

Arterial thrombosis and embolism in malignancy.

In most reviews of arterial embolism or thrombosis the source of emboli or the cause of thrombosis can reasonably be established in over 90% of patients. Still about 10% remain without demonstrable cardiac or intraarterial sources. Although hypercoagulability induced by malignancy has been alluded to as a cause of unexplained intravascular thrombosis reports of arterial thromboembolism with such association are rare. Seven patients with unequivocal thromboembolism are presented. Two distinct clinical patterns are observed, one with in situ thrombosis of small arteries and the other with occlusion of large arteries causing limb ischemia or fatal organ infarction. The various pathogenetic mechanisms of arterial thrombosis or embolism in malignancy include sustained spasm of arteries, precipitation of cryoglobulins or other abnormal proteins in small arteries, direct tumor invasion of arteries, fragmentation and embolization of intracardiac or intraarterial metastases and spontaneous arterial thrombosis due to hypercoagulability. The hypercoagulable state can be recognized by the observation of shortened bleeding and clotting times, partial thromboplastin and prothrombin times, elevation of coagulation factors, platelets and yield stress index and resistance to anticoagulation. Patients presenting with arterial thromboembolic events with out demonstrable source should be investigated for malignancy. Conversely patients with malignancy should be searched for evidence of hypercoagulability in an attempt to prevent arterial thromboembolic complications.

Adenocarcinoma↗