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Khan SS, Nessim S, Gray R, Czer LS, Chaux A, Matloff J. Increased mortality of women in coronary artery bypass surgery: evidence for referral bias. Ann Intern Med 1990; 112:561-7. [PMID: 2327676 DOI: 10.7326/0003-4819-112-8-561] [Citation(s) in RCA: 322] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
STUDY OBJECTIVE To determine whether differences in referral reasons explain the higher operative mortality of women in coronary artery bypass surgery. DESIGN Case series. SETTING A tertiary care, private teaching hospital. PATIENTS Consecutive patients who had isolated coronary artery bypass surgery between 1982 and 1987 (total, 2297; 79% male and 21% female). MEASUREMENTS AND MAIN RESULTS The inhospital mortality rate was significantly higher for women than for men (4.6% compared with 2.6%; P = 0.036; 95% CI for difference in mortality, 0% to 4.0%). Women were older than men (mean, 68.2 and 64.0 years, respectively; P less than 0.001), and a higher percentage of women were referred with unstable angina (P = 0.007), postmyocardial infarction angina (P = 0.029), congestive heart failure (P less than 0.001), and New York Heart Association class IV symptoms (66% compared with 45%, P less than 0.001). More men were referred with a history of an abnormal exercise test (P less than 0.001), and patients referred because of a positive exercise test had a lower mortality (P less than 0.001). Using multivariate analysis, adjustment for the higher preoperative functional class of women and for age accounted for all of the difference in mortality between men and women (odds ratio, 1.04; CI, 0.60 to 1.79; P = 0.89). After correction for functional class alone, there continued to be no significant difference in mortality between men and women (P = 0.40). CONCLUSIONS Differences in functional class and age account for the higher operative mortality of women in coronary bypass surgery. Women are referred for coronary bypass surgery later in the course of their disease than men, and later referral may increase their changes of operative death.
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Khan SS, Trento A, DeRobertis M, Kass RM, Sandhu M, Czer LS, Blanche C, Raissi S, Fontana GP, Cheng W, Chaux A, Matloff JM. Twenty-year comparison of tissue and mechanical valve replacement. J Thorac Cardiovasc Surg 2001; 122:257-69. [PMID: 11479498 DOI: 10.1067/mtc.2001.115238] [Citation(s) in RCA: 147] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
OBJECTIVE We sought to compare outcomes with tissue and St Jude Medical mechanical valves over a 20-year period. METHODS Valve-related events and overall survival were analyzed in 2533 patients 18 years of age or older undergoing initial aortic, mitral, or combined aortic and mitral (double) valve replacement with a tissue valve (Hancock, Carpentier-Edwards porcine, or Carpentier-Edwards pericardial) or a St Jude Medical mechanical valve. Total follow-up was 13,390 patient-years. There were 666 St Jude Medical aortic valve replacements, 723 tissue aortic valve replacements, 513 St Jude Medical mitral valve replacements, 402 tissue mitral valve replacements, 161 St Jude Medical double valve replacements, and 68 tissue double valve replacements. The mean age was 68 +/- 13.3 years (St Jude Medical valve, 64.5 +/- 12.9; tissue valve, 72.0 +/- 12.6). RESULTS There were no overall differences in survival between tissue and mechanical valves. Multivariable analysis indicated that the type of valve did not affect survival. Analysis by age less than 65 years or 65 years or older and presence or absence of coronary disease revealed similar long-term survival in all subgroups. The risk of hemorrhage was lower in patients receiving tissue aortic valve replacements but was not significantly different in patients receiving mitral valve or double valve replacements. Thromboembolism rates were similar for tissue and mechanical valve recipients. However, reoperation rates were significantly higher in patients receiving both aortic and mitral tissue valves. The reoperation hazard increased progressively with time both in patients receiving aortic and in those receiving mitral tissue valves. Overall valve complications were initially higher with mechanical aortic valves but not with mechanical mitral valves. However, valve complication rates later crossed over, with higher rates in tissue valve recipients after 7 years in patients undergoing mitral valve replacement and 10 years in those undergoing aortic valve replacement. CONCLUSIONS Tissue and mechanical valve recipients have similar survival over 20 years of follow-up. The primary tradeoff is an increased risk of hemorrhage in patients receiving mechanical aortic valve replacements and an increased risk of late reoperation in all patients receiving tissue valve replacements. The risk of tissue valve reoperation increases progressively with time.
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Silber H, Khan SS, Matloff JM, Chaux A, DeRobertis M, Gray R. The St. Jude valve. Thrombolysis as the first line of therapy for cardiac valve thrombosis. Circulation 1993; 87:30-7. [PMID: 8419020 DOI: 10.1161/01.cir.87.1.30] [Citation(s) in RCA: 110] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
BACKGROUND Thrombolytic therapy is a promising alternative to valve replacement in the management of prosthetic valve thrombosis. We sought to determine the short- and long-term results of treating thrombosed St. Jude heart valves with thrombolytic therapy as the primary treatment modality. METHODS AND RESULTS Between March 1978 and December 1991, 988 patients underwent implantation of St. Jude prosthetic valves at our medical center, and all patients with thrombosed valves were identified prospectively. During this period, 17 patients (13 women; mean age, 66.8 +/- 19.0 years) developed prosthetic valve thrombosis (11 aortic, six mitral). In six patients, Coumadin was stopped in preparation for elective surgery. The clinical presentation was congestive heart failure in 13, syncope and fatigue in two, and a cerebrovascular accident in one; one patient was asymptomatic. The average duration of symptoms was 11.7 +/- 12.0 days (range, 1-45 days). Anticoagulation was subtherapeutic in all but one patient at the time of presentation. Cinefluoroscopy was the primary method used for diagnosis and was also used to follow the response to therapy. Twelve patients were treated medically (10 with thrombolytic therapy and two with heparin), three were treated surgically, and two were diagnosed at autopsy. Of the 12 medically treated patients, 10 had marked improvement in leaflet movement and symptoms within 12 hours. Thus, 10 of 12 patients (83%) had a satisfactory response to medical therapy alone. No medically treated patient died or had a major complication resulting in permanent damage. However, four of the 12 medically treated patients had minor complications, including a transient episode of facial weakness in one patient, hematomas in two, and epistaxis in one. Late rethrombosis recurred in two patients in the medically treated group and was successfully retreated with thrombolytic therapy. At 3 months, all patients were alive and well. CONCLUSIONS Thrombolytic therapy can be used as the first line of therapy for thrombosed St. Jude valves with a low risk of permanent side effects and excellent chances of success. In most cases, surgery can be reserved for patients who do not respond to thrombolytic therapy.
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Tsai TP, Chaux A, Matloff JM, Kass RM, Gray RJ, DeRobertis MA, Khan SS. Ten-year experience of cardiac surgery in patients aged 80 years and over. Ann Thorac Surg 1994; 58:445-50; discussion 450-1. [PMID: 8067847 DOI: 10.1016/0003-4975(94)92225-x] [Citation(s) in RCA: 108] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Five hundred twenty-eight consecutive patients aged 80 years and over (mean age, 83.1 +/- 2.7 years) underwent cardiac operations with hypothermia (mean, 21.9 degrees +/- 2.2 degrees C), hyperkalemic cardioplegia, and cardiopulmonary bypass in a 10-year period. Fifty-six percent of the patients were male. Preoperatively, 68% of the patients were in New York Heart Association functional class IV, and 31% were in class III. Among them, 303 patients had isolated coronary artery bypass grafting (CABG) (group I), 132 had aortic valve replacement only or combined with CABG (group II), 42 had mitral valve replacement only or combined with CABG (group III), 31 had mitral valve repair and CABG (group IV), and 20 had double-valve procedure only or combined with CABG (group V). The 30-day or in-hospital mortality was 8.3% in group I, 4.5% in group II, 29% in group III, 23% in group IV, and 30% in group V. Total 30-day or in-hospital mortality was 10.6%. One-year and 5-year actuarial survival rates were as follows: group I, 82% and 62%; group II, 85% and 58%; group III, 61% and 37%; group IV, 56% and 19%; and group V, 63% and 15%. Total 1-year and 5-year actuarial survival were 79% and 54%. At follow-up (mean, 2 years), 70% of overall survivors reported that their general health had improved. Our experience demonstrates that for select patients aged 80 years and over with unmanageable cardiac symptoms, CABG and aortic valve replacement groups had better results in improving quality of life as compared with patients having mitral or combined procedures.
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Cipolotti L, Husain M, Crinion J, Bird CM, Khan SS, Losseff N, Howard RS, Leff AP. The role of the thalamus in amnesia: a tractography, high-resolution MRI and neuropsychological study. Neuropsychologia 2008; 46:2745-58. [PMID: 18597798 DOI: 10.1016/j.neuropsychologia.2008.05.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2007] [Revised: 05/06/2008] [Accepted: 05/11/2008] [Indexed: 11/18/2022]
Abstract
Although it is well established that thalamic lesions may lead to profound amnesia, the precise contribution of thalamic sub-regions to memory remains unclear. In an influential article Aggleton and Brown proposed that recognition memory depends on two processes supported by distinct thalamic and cortical structures. Familiarity is mediated by the mediodorsal (MD) thalamic nucleus and the entorhinal/perirhinal cortex. Recollection is mediated by the anterior thalamic nucleus (AN), the mamillothalamic tract (MTT) and the hippocampus. The authors also suggested that the lateral dorsal nucleus (LD) may contribute to the thalamic/hippocampus system, thereby implying that the LD may play a role in recollection. Given the finding that material specific amnesia can occur following thalamic lesions, we tested an extension of the Aggleton and Brown model. We predicted that patients with bilateral lesions with a bias to the left or right MD or AN/MTT/LD may exhibit impaired familiarity or recollection on verbal or non-verbal memoranda. We report two patients with highly focal thalamic lesions and profound memory impairments affecting verbal and non-verbal memoranda. For the first time, diffusion-weighted imaging was employed to perform tractography of the MTT along with high-resolution anatomical MRI and detailed assessments of verbal and non-verbal memory. Our data support only some aspects of the Aggleton and Brown model. Both patients had left MD nucleus and AN/MTT lesions and performed poorly on familiarity and recall for verbal memoranda, just as predicted by the model. However, both patients' performance for non-verbal memoranda (human faces and topography) is more difficult to reconcile with the model. Patient 1 had damage to the right AN/MTT/LD with sparing of the MD: familiarity should therefore have been preserved but was not. Patient 2 had damage to the right MD with sparing of AN/MTT: recollection should have been preserved but was not. This finding raises the possibility that fractionation of familiarity and recollection to separate thalamic nuclei may not fully capture the role of thalamic sub-regions in memory function.
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Research Support, Non-U.S. Gov't |
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Tsai TP, Nessim S, Kass RM, Chaux A, Gray RJ, Khan SS, Blanche C, Utley C, Matloff JM. Morbidity and mortality after coronary artery bypass in octogenarians. Ann Thorac Surg 1991; 51:983-6. [PMID: 2039331 DOI: 10.1016/0003-4975(91)91024-p] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
One hundred fifty seven consecutive octogenarians (mean age +/- standard deviation, 82.4 +/- 1.9 years) underwent coronary artery bypass grafting with hypothermia (mean temperature, 21.8 degrees +/- 1.8 degrees C), hyperkalemic cardioplegia, and cardiopulmonary bypass in a 9-year period. Sixty-six percent were male. Preoperatively, 115 patients (73%) were in New York Heart Association functional class IV, with the remainder being in either class III (23%) or class II (4%). Twenty percent of the patients had major complications including postoperative hemorrhage (15), sepsis (9), cerebrovascular accident (6), third-degree heart block (5), renal failure requiring dialysis (1), and pulmonary embolism (1). The 30-day or in-hospital mortality rate was 7.0%. Mean total hospital stay was 26.1 +/- 17.9 days. One-year and 5-year actuarial survival rates were 85% and 62%, respectively. Higher mortality was seen to be associated with New York Heart Association class IV, left ventricular ejection fraction less than 0.40, and lesser values for cardiac output and cardiac index. At the 6-month postoperative follow-up, 73% of the survivors reported that their general health had improved as compared with before operation. This experience demonstrates that for select octogenarians with unmanageable angina pectoris, coronary artery bypass grafting is an effective therapeutic option.
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Baumgartner H, Khan SS, DeRobertis M, Czer LS, Maurer G. Doppler assessment of prosthetic valve orifice area. An in vitro study. Circulation 1992; 85:2275-83. [PMID: 1591841 DOI: 10.1161/01.cir.85.6.2275] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND Although Doppler echocardiography has been shown to be accurate in assessing stenotic orifice areas in native valves, its accuracy in evaluating the prosthetic valve orifice area remains undetermined. METHODS AND RESULTS Doppler-estimated valve areas were studied for their agreement with catheter-derived Gorlin effective orifice areas and their flow dependence in five sizes (19/20-27 mm) of St. Jude, Medtronic-Hall, and Hancock aortic valves using a pulsatile flow model. Doppler areas were calculated three ways: using the standard continuity equation; using its simplified modification (peak flow/peak velocity); and using the Gorlin equation with Doppler pressure gradients. The results were compared with Gorlin effective orifice areas derived from direct flow and catheter pressure measurements. Excellent correlation between Gorlin effective orifice areas and the three Doppler approaches was found in all three valve types (r = 0.93-0.99, SEE = 0.07-0.11 cm2). In Medtronic-Hall and Hancock valves, there was only slight underestimation by Doppler (mean difference, 0.003-0.25 cm2). In St. Jude valves, however, all three Doppler methods significantly underestimated effective orifice areas derived from direct flow and pressure measurements (mean difference, 0.40-0.57 cm2) with differences as great as 1.6 cm2. In general, the modified continuity equation calculated the largest Doppler areas. When orifice areas were calculated from the valve geometry using the area determined from the inner valve diameter reduced by the projected area of the opened leaflets, Gorlin effective orifice areas were much closer to the geometric orifice areas than Doppler areas (mean difference, 0.40 +/- 0.31 versus 1.04 +/- 0.20 cm2). In St. Jude and Medtronic-Hall valves, areas calculated by either technique did not show a consistent or clinically significant flow dependence. In Hancock valves, however, areas calculated by both the continuity equation and the Gorlin equation decreased significantly (p less than 0.001) with low flow rates. CONCLUSIONS Doppler echocardiography using either the continuity equation or Gorlin formula allows in vitro calculation of Medtronic-Hall and Hancock effective valve orifice areas but underestimates valve areas in St. Jude valves. This phenomenon is due to localized high velocities in St. Jude valves, which do not reflect the mean velocity distribution across the orifice. Valve areas are flow independent in St. Jude and Medtronic-Hall prostheses but decrease significantly with low flow in Hancock valves, suggesting that bioprosthetic leaflets may not open fully at low flow rates.
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Comparative Study |
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Fazal N, Shamim M, Khan SS, Gamelli RL, Sayeed MM. Neutrophil depletion in rats reduces burn-injury induced intestinal bacterial translocation. Crit Care Med 2000; 28:1550-5. [PMID: 10834710 DOI: 10.1097/00003246-200005000-00048] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE To determine whether neutrophil depletion could eradicate intestinal bacterial translocation in bum-injured rats. DESIGN Prospective, randomized, controlled study. SETTING University research laboratory. SUBJECTS Adult male Sprague-Dawley rats. INTERVENTIONS The rats were intravenously administered a rabbit anti-rat neutrophil antibody causing profound neutropenia and subjected to a 30% total body surface area scald burn. MEASUREMENTS AND MAIN RESULTS The depletion of neutrophils from the intestine was assessed via measurements of myeloperoxidase (MPO) activity in the intestinal homogenates. In addition, the presence of activated/extravasated neutrophils in intact intestines was determined via immunohistochemical localization of neutrophil nicotinamide adenine dinucleotide phosphate (NADPH) oxidase component protein p47phox. Bacterial translocation was measured using agar cultures and by determining Escherichia coli beta-galactosidase gene via polymerase chain reaction/Southern blot analyses of mesenteric lymph node and spleen, liver, lung, and blood. MPO measurements demonstrated a six-fold increase above the control value in the intestinal tissue in rats on day 1 postburn. The presence of activated neutrophils (expression of p47phox protein) was also markedly increased in the intestines of these rats. The increased MPO activity and p47phox expression accompanied a translocation of indigenous E. coli into the mesenteric lymph node without a spread to other organs. The administration of anti-neutrophil antibody to burn animals prevented an increase in MPO activity and bacterial translocation. CONCLUSION These studies indicate that enhanced intestinal bacterial translocation caused by burn injury could be related to the increased infiltration of activated neutrophils into the intestinal tissue after bum. The release of neutrophil products such as superoxide anion may effect intestinal tissue damage leading to bacterial translocation of indigenous E. coli.
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Brasch AV, Khan SS, DeRobertis MA, Kong JH, Chiu J, Siegel RJ. Change in mitral regurgitation severity after aortic valve replacement for aortic stenosis. Am J Cardiol 2000; 85:1271-4. [PMID: 10802019 DOI: 10.1016/s0002-9149(00)00746-3] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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Karagueuzian HS, Khan SS, Hong K, Kobayashi Y, Denton T, Mandel WJ, Diamond GA. Action potential alternans and irregular dynamics in quinidine-intoxicated ventricular muscle cells. Implications for ventricular proarrhythmia. Circulation 1993; 87:1661-72. [PMID: 8491022 DOI: 10.1161/01.cir.87.5.1661] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Cardiac cells display rate-dependent beat-to-beat variations in action-potential duration (APD), action potential amplitude (APA), and excitability during periodic stimulation. We hypothesized that quinidine causes a marked increase in the variability of APD, APA, and excitability of ventricular cells isolated from quinidine-toxic, arrhythmic ventricles. METHODS AND RESULTS Action potentials were recorded from right ventricular endocardial tissues (2 x 1 cm, < 2 mm thick) isolated from dogs in which ventricular tachycardia and ventricular fibrillation (VT/VF) were induced with intravenous quinidine (80-100 mg/kg) over a 5-hour period in vivo (n = 7). As the basic cycle length (BCL) of stimulation was progressively shortened, rate-dependent variations in APD and APA occurred. The initial dynamic change was alternans of APD and APA that could be either in or out of phase between two cells. The magnitude of alternans was a function of the BCL and the strength of the stimulation current. At critically short BCLs, irregular APD and APA behavior emerged in the quinidine-intoxicated cells. In control cells (n = 16) isolated from three nontreated dogs, APD and APA remained constant at all BCLs tested (2,000-300 msec). Quinidine increased the slope of the APD restitution curve compared with control. The observed quinidine APD restitution curve was fitted with a biexponential equation, and computer simulation using the fitted restitution curve reproduced the aperiodic APD seen in the quinidine toxic cells during periodic stimulation. Thus, the observed irregular APD behavior was predictable from the restitution curve. CONCLUSIONS Quinidine toxicity increases the temporal and spatial variability of APD and APA in the ventricle that may promote the initiation of reentrant VT/VF in vivo. The slope of the APD restitution curve provides a method to quantitate inhomogeneities in repolarization time and could be a useful marker for proarrhythmia.
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Blanche C, Matloff JM, Denton TA, Khan SS, DeRobertis MA, Nessim S, Chaux A. Cardiac operations in patients 90 years of age and older. Ann Thorac Surg 1997; 63:1685-90. [PMID: 9205168 DOI: 10.1016/s0003-4975(97)00091-x] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Growth of the elderly population worldwide, and specifically in the United States, will continue to accelerate and will have a profound impact on the cost and delivery of health care resources in the future. A medical strategy that allows the elderly to live independently is essential to most cost-effective use of our resources. The question remains as to what will be the future of surgical therapy for this increasing population. METHODS We retrospectively studied the cases of 30 consecutive nonagenarians (mean age, 92.3 +/- 1.8 years) who underwent a cardiac operation within a 9-year period. All patients were in New York Heart Association class III or IV and underwent operation urgently or emergently. RESULTS The 30-day mortality rate was 10%, and the actuarial survival rates were 81% +/- 8% and 75% +/- 9% at 1 year and 2 years, respectively. Seventy-eight percent of survivors were in New York Heart Association class I or II within 2 years after operation and had an improved quality of life. The cost of providing care in this age group was 24% higher than in octogenarians. CONCLUSIONS Advanced age in and of itself (>90 years) should not be a contraindication to an open-heart operation, although morbidity, mortality, and cost may be higher. However, selective criteria identifying risks and benefits for individual patients should be applied. The aging of our population will have a profound impact on the cost and delivery of health care resources in the future. This issue must be addressed in the current debate on the provision of expensive procedures under a realigned national health-care system.
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Kobayashi Y, Peters W, Khan SS, Mandel WJ, Karagueuzian HS. Cellular mechanisms of differential action potential duration restitution in canine ventricular muscle cells during single versus double premature stimuli. Circulation 1992; 86:955-67. [PMID: 1516208 DOI: 10.1161/01.cir.86.3.955] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
BACKGROUND We tested the hypothesis that action potential duration (APD) restitution of normal ventricular muscle cells is different during double premature stimuli (S3) compared with a single premature stimulus (S2). We propose a possible ionic mechanism for such a difference. METHODS AND RESULTS Action potentials and isometric tension were recorded simultaneously from isolated canine right ventricular trabeculae (2 x 2 x 10 mm) (n = 35). APD and tension restitution curves (APD) and peak tension versus diastolic interval [DI] of S2 and S3 were constructed by the extrastimulus method during pacing at 1,500 msec. The following results were obtained. 1) The APD restitution curve of S2 was different from that of S3. During the restitution of S2, an early biphasic upward hump was present at short DIs. In contrast, a smooth exponential rise was consistently seen during S3 restitution. 2) Peak tension remained significantly (p less than 0.001) lower during the restitution of S2 than during S3 restitution at all DIs tested. 3) The variation of APD during the initial 100 msec of DI was significantly longer during S3 than S2 (22 +/- 5 msec versus 41 +/- 5 msec, p less than 0.001). 4) Caffeine (2 mM, n = 5) and ryanodine (10 microM, n = 5) blocked cyclic variations of tension, presumably by blocking cyclic variations of intracellular calcium ion concentrations ([Ca2+]i), and eliminated the differences in APD restitution between S2 and S3. 5) Nisoldipine at high (5 microM) but not at lower (2 microM, n = 5) concentration eliminated the differences in restitution of both APD and tension between S2 and S3. 6) BAY K 8644 (100 nM, n = 5) had no effect on this difference. CONCLUSIONS Greater variations of APD occur during the restitution of S3 than during S2 at short DIs. These differences appear to be caused by cyclic variations in tension and thus in [Ca2+]i. Calcium-sensitive outward currents could explain these differences in APD restitution.
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Tsai TP, Denton TA, Chaux A, Matloff JM, Kass RM, Blanche C, Khan SS. Results of coronary artery bypass grafting and/or aortic or mitral valve operation in patients > or = 90 years of age. Am J Cardiol 1994; 74:960-2. [PMID: 7977134 DOI: 10.1016/0002-9149(94)90599-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Sanderson SJ, Khan SS, McCartney RG, Miller C, Lindsay JG. Reconstitution of mammalian pyruvate dehydrogenase and 2-oxoglutarate dehydrogenase complexes: analysis of protein X involvement and interaction of homologous and heterologous dihydrolipoamide dehydrogenases. Biochem J 1996; 319 ( Pt 1):109-16. [PMID: 8870656 PMCID: PMC1217742 DOI: 10.1042/bj3190109] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Optimal conditions for rapid and efficient reconstitution of pyruvate dehydrogenase complex (PDC) activity are demonstrated by using an improved method for the dissociation of the multienzyme complex into its constituent E1 (substrate-specific 2-oxoacid decarboxylase) and E3 (dihydrolipoamide dehydrogenase) components and isolated E2/X (where E2 is dihydrolipoamide acyltransferase) core assembly. Selective cleavage of the protein X component of the purified E2/X core with the proteinase arg C decreases the activity of the reconstituted complex to residual levels (i.e. 8-12%); however, significant recovery of reconstitution is achieved on addition of a large excess (i.e. 50-fold) of parent E3. N-terminal sequence analysis of the truncated 35,000-M(r) protein X fragment locates the site of cleavage by arg C at the extreme N-terminal boundary of a putative E3-binding domain and corresponds to the release of a 15,000-M(r) N-terminal fragment comprising both the lipoyl and linker sequences. In native PDC this region of protein X is shown to be partly protected from proteolytic attack by the presence of E3. Recovery of complex activity in the presence of excess E3 after arg C treatment is thought to result from low-affinity interactions with the partly disrupted subunit-binding domain on X and/or the intact analogous subunit binding domain on E2. Contrasting recoveries for arg C-modified E2/X/E1 core, and untreated E2/E1 core of the 2-oxoglutarate dehydrogenase complex, reconstituted with excess bovine heart E3, pig heart E3 or yeast E3 point to subtle differences in subunit interactions with heterologous E3s and offer an explanation for the inability of previous investigators to achieve restoration of PDC function after selective proteolysis of the protein X component.
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Yadav N, Francis AP, Priya VV, Patil S, Mustaq S, Khan SS, Alzahrani KJ, Banjer HJ, Mohan SK, Mony U, Rajagopalan R. Polysaccharide-Drug Conjugates: A Tool for Enhanced Cancer Therapy. Polymers (Basel) 2022; 14:polym14050950. [PMID: 35267773 PMCID: PMC8912870 DOI: 10.3390/polym14050950] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 02/21/2022] [Accepted: 02/23/2022] [Indexed: 02/07/2023] Open
Abstract
Cancer is one of the most widespread deadly diseases, following cardiovascular disease, worldwide. Chemotherapy is widely used in combination with surgery, hormone and radiation therapy to treat various cancers. However, chemotherapeutic drugs can cause severe side effects due to non-specific targeting, poor bioavailability, low therapeutic indices, and high dose requirements. Several drug carriers successfully overcome these issues and deliver drugs to the desired sites, reducing the side effects. Among various drug delivery systems, polysaccharide-based carriers that target only the cancer cells have been developed to overcome the toxicity of chemotherapeutics. Polysaccharides are non-toxic, biodegradable, hydrophilic biopolymers that can be easily modified chemically to improve the bioavailability and stability for delivering therapeutics into cancer tissues. Different polysaccharides, such as chitosan, alginates, cyclodextrin, pullulan, hyaluronic acid, dextran, guar gum, pectin, and cellulose, have been used in anti-cancer drug delivery systems. This review highlights the recent progress made in polysaccharides-based drug carriers in anti-cancer therapy.
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Karagueuzian HS, Khan SS, Peters W, Mandel WJ, Diamond GA. Nonhomogeneous local atrial activity during acute atrial fibrillation: spectral and dynamic analysis. Pacing Clin Electrophysiol 1990; 13:1937-42. [PMID: 1704571 DOI: 10.1111/j.1540-8159.1990.tb06920.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Atrial fibrillation (A Fib) has been categorized into four different types (I-IV) based on the morphology of the epicardial bipolar electrogram. In the present study, we hypothesized that these same types of A Fib also exist at endocardial sites. Simultaneous high, mid, and low right atrial endocardial bipolar electrograms were analyzed during acute A Fib induced by a rapid train of stimuli (20-40 Hz) for 1-3 seconds in anesthetized closed-chest dogs (N = 7, total of 72 episodes). A Fib lasted between 3 seconds and a few minutes (22.3 +/- 22.8 sec). During A Fib, bipolar electrograms (0.5-500 Hz) were both discrete (types I and II) on electrograms recorded at one site and at the same time irregular (type III) on electrograms recorded at another site. The three simultaneously recorded electrograms encompassed all combinations of the four types of A Fib. When A Fib had a discrete electrogram morphology (types I and/or II), the mean rate of the A Fib was 494 +/- 93 beats/min. At a given site, electrogram morphology also changed type over time. Fast Fourier transform (FFT) of the digitized electrograms (8-10 sec, 800 Hz digitization) showed peaks mostly below 15 Hz (range 0-30 Hz), that were either discrete (narrow band) with clear harmonic components, or had continuous (broad band) spectra, that changed in a time and site dependent manner. Phase plane plots (PPP), a plot of voltage versus rate of change of voltage, varied with respect to time and location. However, the morphology of these PPP often inscribed well defined structure suggesting dynamics compatible with deterministic chaos, rather than random dynamics.(ABSTRACT TRUNCATED AT 250 WORDS)
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Blanche C, Khan SS, Chaux A, Denton TA, Sandhu M, Tsai TP, Trento A. Cardiac reoperations in octogenarians: analysis of outcomes. Ann Thorac Surg 1999; 67:93-8. [PMID: 10086531 DOI: 10.1016/s0003-4975(98)01064-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
BACKGROUND With the rapid growth of the elderly segment of the population, more octogenarians are referred for complex cardiac interventions, including reoperations. Data regarding the outcomes, quality of life, and long-term results after reoperative open-heart surgical procedures in octogenarians are scarce. METHODS We retrospectively studied 113 consecutive octogenarians (mean age, 83+/-2.6 years) who underwent reoperative cardiac procedures within a 13-year period. Coronary artery bypass grafting (CABG) was performed in 49 patients (CABG group), valvular procedures (aortic, mitral, or tricuspid valve, alone or in combination) in 35 (valve group), and combined CABG and valve intervention in 29 (combined CABG and valve group). RESULTS The 30-day mortality rate was 8% (4 of 49) for the CABG group, 9% (3 of 35) for the valve group, and 17% (5 of 29) for the combined CABG and valve group. One- and 5-year actuarial survival rates were, respectively, 85%+/-5% and 58%+/-10% for the CABG group, 78%+/-7% and 53%+/-12% for the valve group, and 69%+/-9% and 63%+/-10% for the combined CABG and valve group. Sixty-one percent of patients in the CABG group, 40% in the valve group, and 38% in the combined CABG and valve group were in New York Heart Association class I or II postoperatively at a mean follow-up time of 2.1+/-2.4 years. Similarly, 91%, 85%, and 80%, respectively, thought that they had an improved quality of life and were satisfied with their functional status. CONCLUSIONS Cardiac reoperations can be performed successfully in most octogenarians, although with an increased risk, particularly in the combined CABG and valve group. Long-term survival is acceptable with improved quality of life and functional status. However, it is possible that these results could be improved in this high-risk group of patients with earlier referral and surgical intervention, for the effective use of health care resources.
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Farook VA, Khan SS, Manimohan P. A checklist of agarics (gilled mushrooms) of Kerala State, India. MYCOSPHERE 2012. [DOI: 10.5943/mycosphere/4/1/6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Khan SS, Siegel RJ, DeRobertis MA, Blanche CE, Kass RM, Cheng W, Fontana GP, Trento A. Regression of hypertrophy after Carpentier-Edwards pericardial aortic valve replacement. Ann Thorac Surg 2000; 69:531-5. [PMID: 10735693 DOI: 10.1016/s0003-4975(99)01389-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
BACKGROUND The purpose of this study was to determine whether significant regression of left ventricular hypertrophy is seen after implantation of small sizes (19 to 23 mm) of the Carpentier-Edwards (CE) pericardial valve, a stented pericardial valve. METHODS Echocardiograms and electrocardiograms (ECGs) were performed at least 1 year after surgery (mean 18 months) in patients with 19-, 21-, and 23-mm CE pericardial aortic valves and compared with preoperative echocardiograms and ECGs. RESULTS A total of 41 patients, mean age 79 +/- 9 years (range 46 to 93 years), were studied, including 7 19-mm, 22 21-mm, and 12 23-mm patients. The mean postoperative gradient was 22 +/- 7 mm Hg for 19-mm valves, 18 +/- 5 mm Hg for 21-mm valves, and 16 +/- 4 mm Hg for 23-mm valves. The postoperative valve areas were 1.1 +/- 0.3 cm2 for the 19-mm, 1.3 +/- 0.3 cm2 for the 21-mm, and 1.5 +/- 0.4 cm2 for the 23-mm valves. Left ventricular end diastolic diameter, end systolic diameter, septal thickness, and posterior wall thickness all decreased significantly (p <0.05) postoperatively. The proportion of patients with significant left ventricular hypertrophy on ECG decreased from 63% to 47% (p = 0.001). Left ventricular mass decreased significantly by echocardiography from 265 g preoperatively to 208 g postoperatively (p = 0.004). Left ventricular mass decreased for each valve size, and the greatest absolute reduction in mass occurred in the 19-mm valve recipients. CONCLUSIONS Implantation of the 19-, 21-, and 23-mm CE pericardial valves results in significant reductions in left ventricular mass. These findings suggest that stented pericardial valves can be used in the small aortic root without the need for aortic root enlargement procedures.
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Abstract
Liver adenomatosis is a rare condition with only 14 cases reported. It is considered to be a distinct entity from liver adenoma. This is the first case in which calcification has been described. The differential diagnosis of multiple calcified lesions in the liver is discussed, and other features of liver adenomatosis.
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Haw WY, Al-Janabi A, Arents BWM, Asfour L, Exton LS, Grindlay D, Khan SS, Manounah L, Yen H, Chi CC, van Zuuren EJ, Flohr C, Yiu ZZN. Global Guidelines in Dermatology Mapping Project (GUIDEMAP): a scoping review of dermatology clinical practice guidelines. Br J Dermatol 2021; 185:736-744. [PMID: 33937976 DOI: 10.1111/bjd.20428] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/28/2021] [Indexed: 11/27/2022]
Abstract
BACKGROUND Clinical practice guidelines (CPGs) play a critical role in standardizing and improving treatment outcomes based on the available evidence. It is unclear how many CPGs are available globally to assist clinicians in the management of patients with skin disease. OBJECTIVES To search for and identify CPGs for dermatological conditions with the highest burden globally. METHODS We adapted a list of 12 dermatological conditions with the highest burden from the Global Burden of Disease (GBD) study 2019. A systematic literature search was done to identify CPGs published between October 2014 to October 2019. The scoping review was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) framework. RESULTS A total of 226 CPGs were included. Melanoma had the greatest representation in the CPGs, followed by dermatitis and psoriasis. Skin cancers had a relatively high CPG representation but with lower GBD disease burden ranking. There was an uneven distribution by geographical region, with resource-poor settings being under-represented. The skin disease categories of the CPGs correlated weakly with the GBD disability-adjusted life-years metrics. Eighty-nine CPGs did not have funding disclosures and 34 CPGs were behind a paywall. CONCLUSIONS The global production of dermatology CPGs showed wide variation in geographical representation, article accessibility and reporting of funding. The number of skin disease CPGs were not commensurate with its disease burden. Future work will critically appraise the methodology and quality of dermatology CPGs and lead to the production of an accessible online resource summarizing these findings.
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Khan SS, Chaux A, Blanche C, Kass RM, Cheng W, Fontana GP, Trento A. A 20-year experience with the Hancock porcine xenograft in the elderly. Ann Thorac Surg 1998; 66:S35-9. [PMID: 9930413 DOI: 10.1016/s0003-4975(98)01027-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND The availability of 20 years of follow-up data on the Hancock porcine valve (Medtronic Inc, Irvine, CA) allows determination of long-term actual and actuarial failure rates in the elderly. METHODS We analyzed outcomes after mitral or aortic valve replacement with the Hancock porcine valve in 491 consecutive patients, comparing actual and actuarial valve failure rates in the elderly (age 65 or older) with those in younger patients. RESULTS The average age of aortic valve replacement recipients was 68+/-14 years (N = 243) and of mitral valve replacement recipients, 64+/-12 years (N = 248). Average follow-up was 7.0 years (1,673 patient-years) for aortic valve replacement and 7.3 years (1,781 patient years) for mitral valve replacement recipients. The median time to reoperation or structural failure was 15.9 years for aortic valve replacement patients and 14.3 years for mitral valve replacement patients. However, few elderly patients survived to 15 years (22% of the elderly aortic valve replacement and 13% of the older mitral valve replacement patients). The 15-year actual reoperation rate was therefore only 10% in the elderly aortic valve replacement compared to 30% in the younger aortic valve replacement patients. For mitral valve replacement, the 15-year actual reoperation rate was 11% in the elderly and 36% in the younger patients. The lifetime reoperation risk (the maximum potential number of patients who might ever undergo reoperation during their lifetime) is the sum of actual survival and actual reoperation rates. The lifetime reoperation risk was 20% or less for elderly aortic valve replacement patients and 18% or less for elderly mitral valve replacement patients. CONCLUSION These data suggest that about 1 in 10 elderly patients (65 years or older) receiving a Hancock valve will require reoperation within 15 years and less than one in five will ever require reoperation in their lifetimes.
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Comparative Study |
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Blanche C, Khan SS, Chaux A, Matloff JM. Postinfarction ventricular septal defect in the elderly: analysis and results. Ann Thorac Surg 1994; 57:1244-7. [PMID: 8179393 DOI: 10.1016/0003-4975(94)91366-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Fifteen elderly patients (age more than 70 years) underwent surgical repair of postinfarction ventricular septal defects during the years 1980 through 1992. The operative (to discharge or < 30 days) mortality rate was 47%, and the complication rate among survivors was 63%. The probability of survival at 1 year was 47% +/- 13%. Because of the small sample size of our patient population, predictive preoperative risk factors associated with early mortality could not be identified with certainty. However, there is a trend suggesting that high right atrial pressures (p = 0.15) and the need of an intraaortic balloon pump preoperatively (p = 0.12) influence 30-day mortality, as previously described in larger series. Of 5 long-term survivors, 3 are in New York Heart Association functional class I and 2 are in class II. Our experience in this group of patients suggests that in the elderly, a very aggressive approach should be taken in recommending early surgical intervention for postinfarction ventricular septal defect before hemodynamic deterioration ensues and severely compromises chances for survival.
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Denton TA, Diamond GA, Khan SS, Karagueuzian H. Can the techniques of nonlinear dynamics detect chaotic behavior in electrocardiographic signals? J Electrocardiol 1991; 24 Suppl:84-90. [PMID: 1552275 DOI: 10.1016/s0022-0736(10)80023-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Brasch AV, Khan SS, Denton TA, DeRobertis MA, Trento A. Twenty-year follow-up of patients with new perioperative Q waves after coronary artery bypass grafting. Am J Cardiol 2000; 86:677-9, A8. [PMID: 10980223 DOI: 10.1016/s0002-9149(00)01052-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
It is unclear whether the development of new Q waves on the electrocardiogram after coronary artery bypass grafting (CABG) is associated with an adverse prognosis. We analyzed the 20-year survival of 227 patients who underwent CABG, and found that new perioperative Q waves had no impact on long-term survival; therefore, conservative management may be appropriate for uncomplicated patients with new Q waves after CABG.
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Comparative Study |
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