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Biomedical subjects

Y Mahomed

Publications and source records attributed to Y Mahomed.

36 records · Page 2Linked to original sources
PubMed1986

Lesser saphenous vein as an alternative conduit of choice in coronary bypass operations.

Dissatisfaction with the use of the greater cephalic vein and the ease of harvest and overall excellent quality of the lesser saphenous vein have caused us to consider this as our alternate conduit of choice when complete revascularization cannot be obtained with the internal mammary artery and greater saphenous vein. We describe our experience with this conduit and our harvesting technique and review the anatomy of this vein.

Coronary Artery Bypass↗
PubMed1985

Postoperative phrenic nerve palsy in patients with open-heart surgery.

We prospectively studied patients undergoing open-heart surgical procedures to evaluate the role of phrenic nerve palsy in the causation of the high incidence of pulmonary complications reported in these patients. Although atelectasis, or infiltrates, or both developed in the left lower lobe of 98% of the patients (43 of 44) with or without similar changes on the right side, only 5 (11%) of the 44 patients had diaphragmatic dysfunction following operation. In 1, the left phrenic nerve became inexcitable; 2 had paresis of the left hemidiaphragm, and 2 had paresis of the right hemidiaphragm. Although damage to the phrenic nerve can occur during open-heart operations, a relatively low incidence of this complication does not support it as the major cause of postoperative pulmonary complications.

Adult↗
PubMed1985

Encircling endocardial incision interrupts efferent vagal-induced prolongation of endocardial and epicardial refractoriness in the dog.

The purpose of this study was to test the hypothesis that vagal efferent nerves travel in the left ventricular subendocardium in a base to apex direction. Efferent vagal stimulation during constant background isoproterenol infusion prolonged left ventricular endocardial and epicardial effective refractory periods in a control state and after a left ventriculotomy performed while dogs were supported by cardiopulmonary bypass. After a 2 mm deep endocardial circumferential incision, efferent vagal stimulation still prolonged the effective refractory period at an endocardial site basal to the encircling endocardial incision, but no longer prolonged the effective refractory period at the endocardium or immediately overlying epicardium apical to the incision. Interpretation of these data suggests that efferent vagal fibers travel in the superficial subendocardium of the canine left ventricle in a base to apex direction, penetrating upward to innervate the epicardium. Conceivably, a lesion such as a subendocardial myocardial infarction could selectively interrupt efferent vagal innervation, leaving sympathetic innervation unopposed. This may be a source of some arrhythmias.

Animals↗
PubMed1985

Atrial level right to left intracardiac shunt associated with postoperative hypoxemia: demonstration with contrast two-dimensional echocardiography.

Transient hypoxemia is not uncommon after major cardiac or thoracic surgery. The differential diagnosis includes atelectasis, pulmonary embolus, pneumonitis, congestive heart failure and several other diverse cardiovascular and pulmonary problems. Less well recognized is transient right to left intracardiac shunting through a patient foramen ovale or previously unsuspected atrial septal defect. Three cases of clinically important hypoxemia associated with right to left shunting after aortocoronary bypass surgery are presented. The right to left shunting was documented with contrast-enhanced echocardiography, which is a simple, inexpensive and accurate means of screening patients for intracardiac right to left shunts and may play a valuable role in the postoperative management of patients.

Aged↗
PubMed1985

Electrophysiologic evaluation of phrenic nerves in severe respiratory insufficiency requiring mechanical ventilation.

Diaphragmatic paralysis in patients with respiratory insufficiency compounds the problems in the management. In the presence of lower lobe atelectasis, pleural effusion, or a patient's poor respiratory effort, fluoroscopic examination is often not a reliable way to diagnose diaphragmatic paralysis. We observed that transcutaneous phrenic nerve stimulation in the neck and recording the diaphragmatic potentials from electrodes placed on the lower part of the chest is a simple, reliable, and noninvasive technique to diagnose diaphragmatic dysfunction at the bedside in critically ill patients. In 14 postoperative patients and one with cervical spinal cord injury with respiratory failure, we found ten patients who showed phrenic nerve dysfunction. Besides diagnostic utility, the electrophysiologic evaluation of phrenic-diaphragmatic function provides critical information needed for therapy.

Adult↗
PubMed1984

Early experience with an implantable cardioverter.

We tested the efficacy and safety of a fully programmable cardioverter weighing 95 g, in terminating sustained ventricular tachycardia. The device was implanted tranvenously under local anesthesia in seven patients. On command from a programmer or automatically, the cardioverter delivered shocks through a lead inserted to the apex of the right ventricle. It also served as a demand ventricular pacemaker and could perform programmed ventricular stimulation or overdrive pacing. Cardioversion of ventricular tachycardia required less than 0.5 J (mean) and was well tolerated by the patients, who were awake and not sedated. In one patient, a shock terminated ventricular tachycardia with the device in the automatic mode but produced atrial fibrillation with a rapid ventricular response that was intermittently recognized as ventricular tachycardia, triggering additional shocks. One such shock in the ST segment produced ventricular fibrillation that was terminated transthoracically in the emergency room, without residual impairment. We conclude from these preliminary observations that cardioversion of sustained ventricular tachycardia by means of an implantable catheter device is feasible, but for the present its use in the automatic mode must be cautious and selective. The unit's small size, ease of implantation, usefulness for noninvasive electrophysiologic studies, programmability, and bradycardia pacing functions are advantages. The next-generation device must be able to defibrillate and provide better differentiation of arrhythmias.

Adult↗
PubMed1984

Electrophysiologic evaluation of diaphragm by transcutaneous phrenic nerve stimulation.

Phrenic nerve function was evaluated by transcutaneous stimulation in the neck and recording the diaphragmatic potential from surface electrodes placed at the ipsilateral seventh intercostal space (7CS) and the xiphoid process (XP). Simultaneous recordings from 7CS and XP electrodes connected together (XP-7CS) and each connected to a remote reference (knee-7CS and knee-XP) disclosed that the 7CS electrode was always more active and showed electropositive activity, whereas the XP electrode, which was only minimally active, showed electronegative response. Out-of-phase summation of opposite polarity activity at the two electrodes resulted in a higher amplitude response in XP-7CS derivation. Phrenic nerve studies are useful in establishing phrenic nerve injury following cardiothoracic operation. They may also provide evidence of phrenic nerve or diaphragmatic involvement in demyelinative neuropathies, motor neuron disease, and muscular dystrophies.

Adult↗
PubMed1983

Anomalous drainage of the right superior vena cava into the left atrium.

A 22 year old man with asymptomatic hypoxemia was found to have a large right to left shunt due to a rare congenital anomaly: total drainage of the right superior vena cava into the left atrium. The anomaly was first suspected after radionuclide angiocardiography was performed using technetium-99m macroaggregated albumin and was confirmed by cardiac catheterization. Contrast echocardiographic and surgical findings are discussed. Other reports on this anomaly are reviewed.

Adult↗
PubMed1980

Squamous cell carcinoma arising in pemphigus vulgaris during immunosuppressive therapy.

A rapidly growing squamous cell carcinoma developed in an area of active pemphigus vulgaris on the cheek of a 45-year-old woman during treatment with prednisone and cyclophosphamide. This is the first reported case of this phenomenon. The roles of solar and drug carcinogenesis, autoimmunity, and immunosuppression in the pathogenesis of this tumor are discussed.

Adult↗
PubMedDate not supplied

Effects of hypothermia on short latency somatosensory evoked potentials in humans.

Short latency somatosensory evoked potentials (SSEPs) elicited by median nerve stimulation were monitored in 14 adult patients undergoing cardiac surgery under cardiopulmonary bypass and induced hypothermia. SSEPs were recorded at 1-2 degrees C steps as the body temperature was lowered from 37 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of the peaks of N10, P14 and N19 components, the prolongation was more severe for the later components so that N10-P14 and P14-N19 interpeak latencies were also prolonged. The temperature-latency relationship had a linear correlation. The magnitude of latency prolongation (msec) with 1 degree C decline in temperature was 0.61, 1.15, 1.56 for N10, P14 and N19 components, respectively, and 0.39 and 0.68 for interpeak latencies N10-P14 and P14-N19, respectively. The rise time and duration of the 3 SSEP components increased progressively with cooling. Cortically generated component, N19, was consistently recordable at a temperature above 26 degrees C, usually disappearing between 20 degrees C and 25 degrees C. On the other hand, more peripherally generated components, N10 and P14, were more resistant to the effect of hypothermia; P14 was always elicitable at 21 degrees C or above, whereas N10 persisted even below 20 degrees C. The amplitude of SSEP components had a poor correlation with temperature; there was a slight tendency for N10 and P14 to increase and for N19 to decrease with declining temperature. Because incidental hypothermia is common in comatose and anesthetized patients, temperature-related changes must be taken into consideration during SSEP monitoring under these circumstances.

Adult↗
PubMedDate not supplied

Heart transplantation in patients with Marfan's syndrome: a survey of attitudes and results.

Our institution performed an orthotopic heart transplantation in a patient with Marfan's syndrome. The immediate postoperative course was complicated with ultimate discharge; however, this patient died within 1 year as a result of an aortic dissection. On the basis of our experience, we surveyed all heart transplant centers listed with the North American Transplant Coordinator Organization for other patients with Marfan's syndrome who had been referred for transplantation. Nearly one third of responding centers evaluated a total of 30 patients with Marfan's syndrome. Of these, only 13 were formally listed for a donor organ and 11 underwent heart transplantation with an operative mortality of 9.1% (n = 1). Posttransplantation morbidity was significant and includes a 40% (n = 4) incidence of thoracic aorta dissection (one fatal) in operative survivors. There were three other non-dissection-related late deaths for an overall survival of 54.4% after a mean follow-up of 33.0 months. In this shared experience, it appears that the known vascular complications of Marfan's syndrome may diminish the anticipated results after heart transplantation. The reluctance to place these patients on heart transplant donor waiting lists can be justified.

Adult↗
PubMedDate not supplied

Triple-drug immunosuppression for heart transplantation in infants and children.

Triple-drug immunosuppression with OKT3 induction is effective rejection prophylaxis in pediatric cardiac allograft recipients. The concerns regarding prevalent lymphoproliferative disease, growth retardation, cytomegalovirus, and other opportunistic infections have not been realized. Since June 1986, 34 pediatric patients, 23 males and 11 females, (age 4 days to 15 years) have undergone orthotopic heart transplantation at our institution. Fifteen patients were less than 6 months old and 13 had type I or II hypoplastic left heart syndrome. There have been four (12%) operative and four (12%) late deaths and a survival rate of 76% after a mean follow-up of 33 months (range, 1 to 82 months). The only deaths attributed to allograft rejection occurred in two newborn recipients (2 and 10 months after surgery) who neither received maintenance steroids nor underwent routine biopsy. The only death from infection (pneumococcus) occurred 6 months after surgery in a 4-year-old patient who was not known to be asplenic. Of the 27 long-term (> 1 year) survivors, 17 (68%) had an average of two rejection episodes during the follow-up period, 10 patients (32%) have been free of graft rejection, and 26 patients (96%) have not experienced a cytomegalovirus infection despite OKT3 induction therapy. Two patients developed lymphoproliferative disease, one of whom was successfully treated by transient reduction of immunosuppression. The other patient died 13 months after transplantation of a lymphoma of the central nervous system. All survivors have demonstrated satisfactory increases in mean height and weight.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗