Biomedical subjects

K Narine

Publications and source records attributed to K Narine.

8 recordsLinked to original sources

PubMed2006

Refined anaesthesia for implantation of engineered experimental aortic valves in the pulmonary artery using a right heart bypass in sheep.

The feasibility of an anaesthetic protocol developed for surgery during right heart bypass in sheep is reported. Seven female Suffolk sheep, weighing 25-35 kg, were selected for the study. Premedication consisted of midazolam and methadone (both 0.1 mg kg(-1) intravenously). Anaesthesia was induced with propofol (2-4 mg kg(-1)) and maintained with isoflurane in oxygen and continuous rate infusions of propofol (5-7 mg kg(-1 )h(-1)) and fentanyl (5 microg kg(-1) bolus, 5 microg kg(-1) h(-1)). Cisatracurium (0.2 mg kg(-1)) provided muscle relaxation. A standard roller pump was used for the extracorporeal circulation. Drugs administered to maintain blood pressure and heart rate within acceptable levels included phenylephrine (3-4 microg kg(-1)), ephedrine (0.1-0.2 mg kg(-1)), nitroglycerine (50-150 microg kg(-1) h(-1)) and metoprolol succinate (30-80 microg kg(-1)). Electrolytes were infused as needed. Postoperative analgesia was provided by an intercostal block (15 mL 0.5% bupivacaine + epinephrine), carprofen (4 mg kg(-1)) and an opioid (methadone 0.1 mg kg(-1) or buprenorphine 0.01 mg kg(-1)). One sheep became hypoxic during the bypass (PaO(2) 47.7 mmHg). Irregularities of the electrocardiogram were observed during manipulation of the heart in all animals. During the initial phase of the bypass, blood pressure decreased in all sheep, accompanied by dilatation of the heart and large intrathoracic veins in five sheep. With appropriate treatment, blood pressure was restored and easily maintained until the end of the bypass. Weaning from the bypass, using an infusion of nitrates, was smooth. One sheep required a blood transfusion because of severe blood loss and another sheep died postoperatively from respiratory complications. Minor irregularities of the electrocardiogram observed during manipulation of the heart were not life threatening and required no treatment. Decreases in blood pressure at the beginning of the bypass can be expected and require treatment. Nitrates are useful in avoiding volume overload during weaning. The anaesthetic protocol is acceptable for surgery under right heart bypass in sheep.

Anesthesia↗

PubMed1999

Pulmonary presentation of Dirofilaria immitis (canine heartworm) in man.

Canine heartworm or Dirofilaria immitis can occasionally infect man. We present the case of a 36-year-old Balkan woman referred to us for a thoracoscopic biopsy of a well defined pulmonary mass. The latter was thoracoscopically resected and proved to be due to Dirofilaria immitis on histopathological examination. To our knowledge this is the second reported case in Western Australia, the first being that reported by Brine et al. The prevalence of the disease in Australia was recognized in 1969 in one study in the state of Queensland, where 12% of 761 dogs at one veterinary clinic and 20% of 296 dogs at another were shown to be infected. Dirofilaria immitis resides in the right ventricle and pulmonary arteries of dogs. The microfilariae are released into the blood stream and are transmitted to secondary hosts by mosquitoes.

Adult↗

PubMed1997

Postoperative hemodynamics of two bileaflet heart valves in the aortic position.

BACKGROUND AND AIMS OF THE STUDY: In vivo hemodynamic assessment of bileaflet aortic valve prostheses using standardized echocardiography is still uncommon; hence, adequate comparison of valve types can rarely be made. We compared the postoperative hemodynamics of St. Jude Standard valves (SJS) with those of Sorin Bicarbon valves (BC) implanted in the aortic position, using pulsed, continuous and color Doppler echocardiography. METHODS: The examination was performed four months after aortic valve prosthesis implantation in 76 patients (39 SJS valves, 37 BC valves). Valve sizes varied from 19 mm to 25 mm. Maximal and mean instantaneous pressure gradients were measured by Doppler echocardiography. Effective valve orifice area (EOA) was calculated and prosthetic valve regurgitation was assessed by color Doppler flow imaging. RESULTS: At valve sizes of 21 mm, 23 mm and 25 mm, SJS valves had a significantly lower EOAs than BC valves (p < 0.05). However, for a given nominal size, BC valves are larger, i.e. they have a larger anatomic (AOA) and geometric orifice area (GOA) than SJS valves. Consequently, BC valves were implanted in patients with a larger left ventricular outflow tract (p < 0.05). When EOA is related to the corresponding AOA, BC valves still show a larger EOA than SJS valves (p < 0.05). Prosthetic valve regurgitation is low in both valve types. CONCLUSIONS: (a) Nominal valve size is not always a good basis for comparison of hemodynamic profiles between valve types. (b) Using the relationship between EOA and AOA, the hemodynamic profile of BC valves in the aortic position is shown to be superior to that of SJS valves.

Aged↗

PubMed1995

Right ventricular outflow reconstruction with homografts.

Ninety children and young adults underwent right ventricular outflow tract (RVOT) reconstruction with aortic or pulmonary homografts from May, 1989 to May, 1994. The patients were divided into three groups according to preoperative diagnosis: RVOT obstructions with ventriculo-arterial (VA) concordance (61), RVOT obstructions with VA discordance (18) and truncus arteriosus (11). Of the reconstructions, 52% were reoperations. A pulmonary homograft was used by preference (85% in the concordant group and 33% in the discordant group). One patient died after homograft correction (hospital mortality 1.1%). The mean follow-up was 32 +/- 22 months. One patient died after 10 months due to congestive heart failure and obstructive pulmonary hypertension. All other patients were in NYHA classes I-II. Three patients (two discordant and one truncus correction) underwent reoperation because of aortic homograft dysfunction and calcification. The incidence of significant (> or = 40 mmHg) gradient across the reconstruction found at the last echocardiographic control was 4% in the concordant, 28% in the discordant, and 18% in the truncus, group. Echocardiographic evidence of moderate (grade 2-3/4) pulmonary regurgitation (PR) was noticed in 24 and 13% of the concordant and discordant groups, respectively. From this medium-term experience it is concluded that (1) the medium-term performance of cryopreserved homografts is excellent, even in young patients, (2) corrections in patients with VA discordance need close follow-up, (3) the use of pulmonary homografts, especially in VA concordant lesions, should be encouraged, (4) longer-term follow-up is necessary to confirm the superiority of the cryopreserved homograft when compared to the porcine xenograft in the RVOT.

Adolescent↗

PubMedDate not supplied

Kangaroo vs. porcine aortic valves: calcification potential after glutaraldehyde fixation.

The aim of this study was to evaluate and compare the calcification potential of kangaroo and porcine aortic valves after glutaraldehyde fixation at both low (0.6%) and high (2.0%) concentrations of glutaraldehyde in the rat subcutaneous model. To our knowledge this is the first report comparing the time-related, progressive calcification of these two species in the rat subcutaneous model. Twenty-two Sprague-Dawley rats were each implanted with two aortic valve leaflets (porcine and kangaroo) after fixation in 0.6% glutaraldehyde and two aortic valve leaflets (porcine and kangaroo) after fixation in 2% glutaraldehyde respectively. Animals were sacrificed after 24 h and thereafter weekly for up to 10 weeks after implantation. Calcium content was determined using inductively coupled plasma-mass spectrometry and confirmed histologically. Mean calcium content per milligram of tissue (dry weight) treated with 0.6 and 2% glutaraldehyde was 116.2 and 110.4 microg/mg tissue for kangaroo and 95.0 and 106.8 microg/mg tissue for porcine valves. Calcium content increased significantly over time (8.8 microg/mg tissue per week) and was not significantly different between groups. Regression analysis of calcification over time showed no significant difference in calcification of valves treated with 0.6 or 2% glutaraldehyde within and between the two species. Using the subcutaneous model, we did not detect a difference in calcification potential between kangaroo and porcine aortic valves treated with either high or low concentrations of glutaraldehyde.

Animals↗

PubMedDate not supplied

The use of the stomach in repairing tracheal leaks after resection of the oesophagus for carcinoma.

A 44-year old male with carcinoma of the upper third of the oesophagus and invasion of the trachea recently underwent surgical treatment at our institution. After oesophageal resection tracheal and main bronchial leaks were unsuccessfully closed with pleural patches. The stomach was subsequently used to seal the remaining leaks. The post-operative recovery was uneventful and the patient was discharged after a hospital stay of 41 days.

Adult↗

PubMedDate not supplied

Heart transplantation.

From September 1988 until March 1990, 22 orthotopic heart transplantations (HTX) were performed in 20 patients (18 male and 2 female). Median age was 56.5 years (23-66). The indication for HTX was an end-stage ischemic disease in 7 pts. a dilated cardiomyopathy in 13 pts, and a retransplantation in 2 pts. The mean waiting time was 58 days. Immunosuppressive therapy included OKT3, prednisone and azathioprine. Cyclosporine was introduced at day 10. Donor hearts were obtained from our institution in 5 cases, from other hospitals in Belgium in 9 cases, and from other European countries in 8 cases. The mean ischemic time was 129 +/- 28 min. No patient died in the operating room. During the first postoperative month, weekly endomyocardial biopsies were performed to detect early rejection. Five patients died in the early postoperative period, mainly from rejection. After a mean hospital stay of 23 days, 15 patients (75%) were discharged. During the late follow-up, 3 patients died: 1 from chronic mediasdinitis, 1 from hypoglycemia, and 1 from cardiac arrest following non-compliance with the medical treatment. In conclusion, early acute rejection after HTX still remains a major cause of death.

Adult↗

PubMedDate not supplied

Paradoxical embolism and acute arterial occlusion.

Paradoxical embolism, due to passage of emboli through an intracardiac defect is now recognised as a cause of acute arterial embolisation. We present the case of a patient in whom unexplained arterial embolisation was diagnosed before further investigation, including contrast echocardiography, revealed a patent foramen ovale associated with pulmonary embolisation and deep venous thrombosis. This report illustrates the often confusing clinical picture that can accompany this syndrome. Early diagnosis and successful management depends on early clinical recognition and appropriate diagnostic procedures.

Angiography, Digital Subtraction↗