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Biomedical subjects

K Ramanathan

Publications and source records attributed to K Ramanathan.

At least 37 records · Page 2Linked to original sources
PubMed1999

Waiting times and prioritization for coronary artery bypass surgery in New Zealand.

OBJECTIVES: To review the New Zealand coronary artery bypass priority score instituted in May 1996, and specifically to determine whether it prioritizes patients at high risk of cardiac events while waiting. The New Zealand score is compared with the Ontario urgency rating score, and waiting times for surgery are compared with the maximum times recommended by the Ontario consensus panel. DESIGN: Retrospective review of patients accepted for isolated coronary artery bypass surgery between 1 January 1993 and 31 January 1996. SETTING: Green Lane Hospital, Auckland, New Zealand. MAIN OUTCOME MEASURES: Waiting time, cardiac death, myocardial infarction, and cardiac readmission. RESULTS: The median waiting times were five days for hospital cases (n = 721) and 146 days for out of hospital cases (n = 701). Of the latter group, 28% waited more than a year, 33% had their surgery expedited because of worsening symptoms, and 19% failed to meet the cut off point set by the New Zealand score for acceptance onto the list. Twenty two patients died, 18 on the outpatient waiting list (waiting list mortality 2.6%, risk 0.28% per month of waiting), and 132 were readmitted, 12% with myocardial infarction and 76% with unstable angina. Risk factors for a composite end point of death or myocardial infarction and/or cardiac readmission were: previous coronary artery bypass surgery (p = 0. 001), class III or IV angina (p = 0.002), and hypertension (p = 0. 005). The New Zealand score did not identify those at risk. Excluding hospital cases, 32% had surgery within the time recommended by the Ontario consensus panel. CONCLUSIONS: Waiting times for coronary artery bypass surgery in New Zealand are considerably longer than those in Ontario, Canada. By using a numerical cut off point, implementation of the New Zealand priority scoring system has restricted access to coronary surgery on the basis of funding constraints rather than clinical appropriateness. The score does not add greatly to the clinicians' prioritization in predicting those patients who will suffer events while waiting.

Adult↗
PubMed1998

Abnormal coronary flow in infarct arteries 1 year after myocardial infarction is predicted at 4 weeks by corrected Thrombolysis in Myocardial Infarction (TIMI) frame count and stenosis severity.

Because 24% to 30% of patent infarct-related arteries occlude in the year following thrombolytic therapy for acute myocardial infarction, angiographic factors including corrected Thrombolysis in Myocardial Infarction (TIMI) frame count which may predict abnormal infarct-artery flow, require definition. We examined changes in coronary flow and infarct-artery lesion severity by computerized quantitative angiography over 1 year in 154 patients with a patent infarct-related artery 4 weeks after myocardial infarction. These patients were randomized to receive either ongoing daily therapy of 50 mg aspirin and 400 mg dipyridamole, or placebo. All angiograms were interpreted blind in our core angiographic laboratory. Infarct-artery flow, assessed by corrected TIMI frame counts, was normal (< or = 27) in 46% and 45% of patients at 4 weeks and 1 year, respectively. At 4 weeks, patients with corrected TIMI frame counts < or = 27 had higher ejection fractions (60+/-11% vs 56+/-12%; p = 0.04) than those with corrected TIMI frame counts >27. On multivariate analysis, corrected TIMI frame count and stenosis severity were predictive of late abnormal infarct-artery flow (TIMI 0 to 2 flow, both p <0.01). Only stenosis severity at 4 weeks predicted reocclusion at 1 year (p <0.0001). Aspirin and dipyridamole had no effect on flow or reocclusion. Thus, corrected TIMI frame count and stenosis severity at 4 weeks was highly correlated with infarct-artery flow at 1 year.

Aged↗
PubMed1998

The relationship between cardiothoracic ratio and left ventricular ejection fraction in congestive heart failure. Digitalis Investigation Group.

BACKGROUND: Left ventricular ejection fraction (EF) is a valuable prognostic index in patients with congestive heart failure (CHF). Although EF can be readily measured, many clinicians use roentgenographic heart size as a clue to differentiate systolic from diastolic dysfunction, even in the absence of solid supportive data. OBJECTIVE: To test the hypothesis that the cardiothoracic ratio (CTR) measured from the chest roentgenogram can be used to estimate left ventricular EF in individuals with CHF. METHODS: To answer this question, the database of the Digitalis Investigation Group trial was used. The CTR, determined using the Danzer method, and quantitative EF, measured locally using angiographic, radionuclide, or 2-dimensional echocardiographic techniques, were compared in 7476 patients with clinical CHF (New York Heart Association functional classes I-IV) due to acquired left-sided cardiac disease of ischemic, hypertensive, idiopathic, and alcohol-related causes. RESULTS: Mean (+/-SD) CTR for the cohort was 0.53+/-.07. Mean (+/-SD) EF was 31.7%+/-12.2%. A weak, negative correlation between CTR and EF was observed (r=-0.176). Similar findings were obtained when the results were stratified by cause of CHF, presence of clinically defined right ventricular dysfunction, and method of EF measurement. Categorical analysis failed to yield a CTR cutoff point that facilitated useful segregation of individuals with an EF greater than 35% or 35% and below; greater than 40% or 40% and below; and greater than 45% or 45% and below in any patient group. CONCLUSIONS: Although a weak, negative correlation exists between CTR and EF, this relationship does not allow for accurate determination of systolic function in individual patients with CHF. Considering the morbidity and mortality associated with CHF, and the clinical implications of systolic function in this syndrome, direct measurement of EF is recommended.

Aged↗
PubMed1998

Early noninvasive identification of failed reperfusion after intravenous thrombolytic therapy in acute myocardial infarction.

OBJECTIVES: This study sought to evaluate a biochemical approach to the early noninvasive assessment of reperfusion. BACKGROUND: In patients with an acute myocardial infarction, a rapid noninvasive method of detecting failure of intravenous thrombolytic therapy to restore early Thrombolysis in Myocardial Infarction (TIMI) grade 3 flow in the infarct-related artery (IRA) is needed. METHODS: Serial blood samples were collected to assay creatine kinase-MB fraction (CKMB mass), cardiac troponin T and myoglobin concentrations in 105 patients with a myocardial infarction who underwent early angiography after intravenous streptokinase. The ratios of the 60- and 90-min concentrations to prethrombolytic values were used to determine an index that could identify failure to achieve TIMI grade 3 flow in the IRA at 90 min. RESULTS: Significant increases in serum concentrations of markers at 60 min were more likely with TIMI grade 3 flow (59 patients) than with TIMI grade 0 to 2 flow (46 patients). Ratios < or = 5 at 60 min after thrombolysis detected failure to achieve 90-min TIMI grade 3 flow with 92% to 97% sensitivity, 43% to 60% specificity and 63% to 76% positive and 86% to 94% negative predictive values. Ratios < or = 10 at 90 min showed 88% to 95% sensitivity, 49% to 65% specificity and 61% to 69% positive and 86% to 94% negative predictive values for TIMI flow grade < 3. The overall predictive values were thus similar for all three markers. CONCLUSIONS: In acute myocardial infarction treated with intravenous streptokinase, a simple measurement of increased serum concentrations of CKMB mass, cardiac troponin T or myoglobin at 60 and 90 min can accurately predict failure to achieve TIMI grade 3 flow in the IRA at 90 min.

Aged↗
PubMed1996

Thrombolytic therapy in the elderly. Pharmacoeconomic considerations.

Elderly patients have the highest absolute risk of death following an acute myocardial infarction (MI); 16.1% for those aged between 65 and 74 years, and 25.3% for those older than 75 years. Therefore, this age-group potentially may benefit most from the use of thrombolytic therapy. Cost-effectiveness analysis of streptokinase therapy has estimated that in patients aged 70 to 80 years, the cost per life-year saved is between $US21,200 and $US22,400 (1990 dollars) compared with placebo treatment. Additional mortality benefits have been shown for accelerated alteplase compared with streptokinase-treated patients (30-day mortality for alteplase and streptokinase was 6.3% and 7.3%, respectively; p = 0.001). A prospective cost-effectiveness study for all age groups concluded that the cost of an additional year of life saved with alteplase compared with streptokinase was $US32,678 (1993 dollars). This extra cost of alteplase treatment declined to $US13,410 and $US16,246 with patients older than 75 years with anterior and inferior MI, respectively. In patients aged 40 years or younger with an anterior or inferior MI, and for those aged up to 60 years with an inferior infarction, the accepted cost-effectiveness ratio of $US50,000 was exceeded. Alteplase appears to be a cost-effective therapy for the treatment of elderly patients with acute MI.

Aged↗
PubMed1995

Single kinesin molecules stressed with optical tweezers.

Using the optical tweezers to pull on microtubules, we have stretched and twisted single kinesin molecules adsorbed to glass surfaces. Preliminary measurements suggest that the mechanical system is very compliant, with an apparent stretch of 120 nm with < 2 pN of force. Although measurements of the series compliance of the bead-microtubule structure are still in progress, the kinesin attachment site does not slip with stretch. However, under torsional stress, kinesin appears to slip. With torques < 2 pN-microns approximately 1 Hz in 2 mM AMP-PNP, there is no apparent limit to the number of revolutions that the microtubule can rotate around the kinesin attachment site (n = 44). Preliminary data from other nucleotide conditions are similar. Although there are rare instances of torsional elasticity where the attachment site unwinds, the restoring forces are not constant with angular position, also indicating slippage. Mechanisms of mechanochemical transduction must account for linear force generation in the presence of angular "slippage."

Adenylyl Imidodiphosphate↗
PubMed1986

Sperm granuloma.

Explore the source record for details and available documents.

Adult↗
PubMed1986

Sonographic demonstration of simultaneous intrauterine and extrauterine gestation.

Simultaneous intrauterine and ectopic pregnancies are extremely rare. The diagnosis is usually made by laparoscopy and/or laparotomy. Three cases are presented in which the diagnosis was made during sonographic examinations by simultaneous demonstration of fetal cardiac motion in both the intrauterine and extrauterine fetuses. Early diagnosis of this condition significantly reduces the morbidity and mortality of both the mother and the intrauterine gestation.

Adult↗
PubMed1985

Squamous cell carcinoma of the oral mucosa in Malaysia--any change?

The prevalence rate of 749 cases of oral squamous cell carcinomas (SCC) recorded between 1978-1984 was studied. Results showed that the Indians formed the dominant group (63.8%) followed by the Malays (19.6%) and Chinese (16.6%). The peak incidences were generally located between the sixth and eighth decades. Only in the Chinese group a male preponderance was noted. In the Indians, the buccal mucosa was the most prevalent site; in the Malays and Chinese males, the gingiva and alveolus; and the Chinese female, the tongue. In all three groups, the well-differentiated SCC was the commonest type and the poorly differentiated least common.

Adult↗
PubMed1985

Oral candidiasis--its pleomorphic clinical manifestations, diagnosis and treatment.

Up to 60% of the population carry Candida albicans as part of the oral flora without having evidence of candidiasis. The pleomorphic clinical manifestations of oral candidiasis viz. thrush, denture stomatitis, angular cheilitis, median rhomboid glossitis, speckled leukoplakia, and chronic mucocutaneous candidiasis and its variants are briefly discussed. Current diagnostic techniques of oral candidiasis (OC) are reviewed. A simple and quick method of helping the clinician in the diagnosis of OC by taking a direct smear of the lesion is emphasized. OC is a 'disease of the diseased'. As a routine a full blood picture, serum iron and serum folate levels should be looked at. Several predisposing causes of OC need to be investigated. An up-date on the treatment of OC with nystatin, amphotericin B lozenges, clotrimazole and miconazole is made.

Candidiasis, Oral↗
PubMed1981

Natural history of contractile abnormalities after acute myocardial infarction in man: severity and response to nitroglycerin as a function of time.

The natural history of contraction abnormalities and their response after acute myocardial infarction in man were studied using radionuclide angiography. Sixteen patients were studied before and after sublingual nitroglycerin within 24 hours, 5-7 days and 4-6 weeks after the onset of chest pain. Within 24 hours, central chord shortening in the zone of infarction was reduced to 13.1 +/- 9.8%, but improved 27.2 +/- 18.4% (p less than 0.001) after nitroglycerin. After 5-7 days, central chord shortening improved similarly, but less markedly, from 12.9 +/- 9.2% to 24.4 +/- 13.2% (p less than 0.001). After nitroglycerin 4--6 weeks after the acute myocardial infarction, the central chord showed no response to nitroglycerin; it was 13.9 +/- 10.9% before and 13.4 +/- 2.5% after nitroglycerin. Changes in the lateral chords paralleled changes in the central chords in the three studies. Nonischemic zone improvement after nitroglycerin in all three studies. Global ejection fraction improved and end-diastolic and end-systolic volumes decreased in all three studies after nitroglycerin. These data indicate that after acute myocardial infarction, there is a significant reduction in hemiaxis shortening in the central and lateral chords that remains essentially unchanged over 4-6 weeks. However, the asynergic ischemic area improves considerably after nitroglycerin within 24 hours and 5-7 days, but fails to improve after 6 weeks.

Acute Disease↗
PubMed1981

Effect of progressive pressure reduction with nitroprusside on acute myocardial infarction in humans. Determination of optimal afterload.

The effect of nitroprusside-induced progressive systemic pressure reduction on segmental function in patients with acute myocardial infarction is unclear. In 15 patients control radionuclide angiograms were obtained at control within 24 hours of the onset of chest pain and during the administration of intravenous nitroprusside. The initial study showed a significant reduction in hemiaxial shortening in the zone of myocardial infarction. With nitroprusside, systolic pressure was decreased from a mean of 133 mm Hg to an intermediate pressure of 116 mm Hg (p less than 0.001). At this pressure central chord hemiaxial shortening increased in eight of 15 zones with an average increase from 10.1% to 27.8% (p less than 0.006). After further reduction in pressure to 87.1 mm Hg, an additional five of the seven remaining zones of acute infarction improved. However, of the eight zones that improved initially, four deteriorated at the lowest pressure. Similar changes were seen in the lateral chords. Thus, afterload reduction can improve hemiaxial shortening of the infarct zone. However, the degree of reduction in systemic pressure must be individualized to avoid adverse effects of an excessive decrease in perfusion pressure.

Adult↗