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Biomedical subjects

K H Sheikh

Publications and source records attributed to K H Sheikh.

At least 19 recordsLinked to original sources
PubMed1993

Etiology of large pericardial effusions.

PURPOSE: To determine the effectiveness of the preoperative evaluation and overall diagnostic efficacy of subxiphoid pericardial biopsy with fluid drainage in patients with new, large pericardial effusions. DESIGN: A prospective interventional case series of consecutive patients admitted with new, large pericardial effusions. PATIENTS AND METHODS: Fifty-seven of 75 consecutive patients admitted to a university tertiary-care center and a university-affiliated Veterans Administration Medical Center with new, large pericardial effusions were studied over a 20-month period. Each patient was assessed by a comprehensive preoperative evaluation followed by subxiphoid pericardiotomy. The patients' tissue and fluid samples were studied pathologically and cultured for aerobic and anaerobic bacteria, fungi, mycobacteria, mycoplasmas, and viruses. RESULTS: A diagnosis was made in 53 (93%) patients. The principle diagnoses consisted of malignancy in 13 (23%) patients; viral infection in 8 (14%) patients; radiation-induced inflammation in 8 (14%) patients; collagen-vascular disease in 7 (12%) patients; and uremia in 7 (12%) patients. No diagnosis was made in four (7%) patients. A variety of unexpected organisms were cultured from either pericardial fluid or tissue: cytomegalovirus (three), Mycoplasma pneumoniae (two), herpes simplex virus (one), Mycobacterium avium-intracellulare (one), and Mycobacterium chelonei (one). The pericardial fluid yielded a diagnosis in 15 (26%) patients, 11 of whom had malignant effusions. The examination of pericardial tissue was useful in the diagnosis of 13 (23%) patients, 8 of whom had an infectious agent cultured. Of the 57 patients undergoing surgery, the combined diagnostic yield from both fluid and tissue was 19 patients (33%). CONCLUSIONS: A systematic preoperative evaluation in conjunction with fluid and tissue analysis following subxiphoid pericardiotomy yields a diagnosis in the majority of patients with large pericardial effusions. This approach may also result in the culturing of "unusual" infectious organisms from pericardial tissue and fluid.

Biopsy↗
PubMed1993

A prospective trial of subxiphoid pericardiotomy in the diagnosis and treatment of large pericardial effusion. A follow-up report.

OBJECTIVE: This study was designed to determine the cause of large pericardial effusions and evaluate the efficacy of subxiphoid pericardiotomy. SUMMARY BACKGROUND DATA: Despite great advances in the techniques used to diagnose pericardial effusions, much controversy remains concerning their cause and the optimal treatment of these effusions. METHODS: In a prospective consecutive case series, 57 patients underwent a thorough preoperative evaluation followed by a subxiphoid pericardiotomy. All tissue and fluid was exhaustively evaluated. Postoperatively, all patients were followed for a least 1 year. RESULTS: Surgery was performed under local anesthesia in 77% of patients, and the complications of surgery were minimal. Pericardial tissue and fluid established or aided in establishing a diagnosis in 81% of patients. Infection and malignancy were the leading causes; the condition in only 4 patients remained undiagnosed. Follow-up revealed recurrent effusion in nine (16%) patients, but only five (9%) required further surgery. The mortality rate at 30 days was 12%, and at 1 year, it was 37%. Fourteen of the 21 deaths occurred in patients with malignancies. CONCLUSIONS: These data show that the cause of most large pericardial effusions can be determined by a thorough evaluation accompanied by subxiphoid pericardiotomy. In addition, subxiphoid pericardial biopsy and window creation is safe and effective in the treatment of these effusions.

Biopsy↗
PubMed1992

Diagnosis and management (by subxiphoid pericardiotomy) of large pericardial effusions causing cardiac tamponade.

To determine the clinical features, course and outcome of patients with cardiac tamponade, 57 consecutive patients with new, large pericardial effusions were prospectively studied. Twenty-five patients (44%) developed cardiac tamponade with venous hypertension and a pulsus paradoxus greater than 10 mm Hg. Electrocardiography, radiographic studies and echocardiography did not differentiate patients with and without tamponade. All 57 patients underwent thorough diagnostic evaluation followed by subxiphoid pericardial biopsy and drainage. A diagnosis was obtained in 53 patients (93%). Collagen vascular disease was significantly more frequent in the 25 patients with than in the 32 without cardiac tamponade (24 vs 3%; p less than 0.05). The frequency of malignant and uremic effusions was equal in both groups, whereas radiation-induced effusions seldom produced tamponade. At 1-year follow-up, 3 patients (12%) with tamponade had recurrent effusions, and 1 needed reoperation. This was not significantly different from the 32 patients without tamponade. Twelve-month mortality was also similar in both groups (36 vs 44%). This prospective series disclosed several unexpected findings: (1) Cardiac tamponade occurred in almost 50% of patients with new large pericardial effusions; (2) both malignancy and collagen vascular disease occurred with equal frequency as etiologies, whereas radiation-induced tamponade was unusual; (3) thorough clinical evaluation resulted in few idiopathic etiologies; and (4) subxiphoid pericardiotomy was effective for both diagnosis and therapy of tamponade.

Cardiac Tamponade↗
PubMed1992

Real-time assessment of experimental arterial angioplasty with transvenous intravascular ultrasound.

Optimal evaluation of experimental angioplasty procedures would allow real-time simultaneous assessment during the procedure without direct manipulation of treated arterial segments. To assess the feasibility and utility of transvenous real-time intravascular ultrasound imaging during experimental angioplasty, 11 consecutive atherosclerotic iliac artery segments in rabbits were imaged before, during and after thermal or conventional perfusion balloon angioplasty. A 20-MHz intravascular ultrasound catheter was positioned in the adjacent vein, and images were correlated with data from quantitative angiography and histologic studies. Images suitable for analysis were obtained at all 11 sites. Arterial distension and recoil were observed during balloon inflation and deflation. Measurements of lumen diameter and cross-sectional area by intravascular ultrasound and angiography were closely correlated (r2 = 0.90, SEE = 0.2 mm, and r2 = 0.90, SEE = 0.8 mm2, respectively). Intimal dissections were identified in six segments by intravascular ultrasound and all were concordant with histologic findings. Thus, real-time transvenous ultrasound avoids manipulation of the treated artery, and is a feasible modality for dynamic quantitative and qualitative assessment of arterial interventions.

Angiography, Digital Subtraction↗
PubMed1992

Subxiphoid pericardiotomy in the diagnosis and management of large pericardial effusions associated with malignancy.

To determine the safety, diagnostic value, and clinical outcome of patients with malignancy undergoing subxiphoid pericardiotomy for large pericardial effusions, we prospectively studied 25 consecutive patients with malignancy and new, large pericardial effusions diagnosed by echocardiography. Twenty-two of the 25 operations were done under local anesthesia, and no patient died at surgery. Pericardial fluid cytology revealed malignant cells in 11 patients (44 percent), while tumor was seen in only five (45 percent) of these 11 patients on pathologic examination. The remaining 14 patients showed no evidence of pericardial invasion with tumor. Evidence of intrathoracic disease by CT or MRI scanning, tamponade, a sanguineous pericardial fluid character, and an elevated serum and pericardial fluid lactate dehydrogenase level all were suggestive of malignant invasion of the pericardium. All 25 patients were followed at least 12 months postoperatively. Effusions recurred in three patients (12 percent), and one patient required reoperation. Overall mortality was 72 percent with a 91 percent (10 of 11) mortality for those with malignant effusions and a 57 percent (8 of 14) mortality for those with nonmalignant effusions. Diagnostically, subxiphoid pericardiotomy has little advantage over examination of pericardial fluid alone in this group of patients. Therapeutically, however, it is a low morbidity procedure which is safe and effective in treating patients with malignancy and large pericardial effusions.

Cardiac Tamponade↗
PubMed1991

Intracoronary ultrasound evaluation of interventional technologies.

The feasibility and applicability of intravascular ultrasound (IVUS) of the coronary arteries were evaluated in 65 patients undergoing 70 coronary interventional procedures. Morphologic and quantitative analyses were performed with a mechanically rotated IVUS catheter (4.8Fr, 20 MHz) and with orthogonal view cineangiography. A semiautomated edge-detection algorithm was used for cineangiographic quantification. Coronary interventions included 45 percutaneous transluminal coronary angioplasties, 9 excimer lasers, 11 directional coronary atherectomies, 3 rotational atherectomies and 2 stents. Most lesions consisted of a mixture of plaque composition (hard, n = 30; soft, n = 64). Other unique morphologic data by IVUS were plaque topography (eccentric, n = 34; concentric, n = 36) and vessel dissection (IVUS [n = 29] versus angiography [n = 14], p less than 0.05). Postprocedure minimal lumen diameter and cross-sectional area measured by IVUS were larger and poorly correlated with angiography (r = 0.28, standard error of the estimate = 0.52 mm; r = 0.08, standard error of the estimate = 1.0 cm2, respectively). IVUS is more sensitive than angiography when assessing postintervention lesion characteristics including vessel dissection and plaque morphology. Catheter-based ultrasound appears to be a useful adjunct to contrast angiography when evaluating and comparing the therapeutic impact of conventional percutaneous transluminal coronary angioplasty with new technologies.

Algorithms↗
PubMed1991

Age-related alterations of Doppler left ventricular filling indexes in normal subjects are independent of left ventricular mass, heart rate, contractility and loading conditions.

The purpose of this study was to determine whether age-related alterations in Doppler diastolic filling indexes occur independent of cardiovascular disease and confounding physiologic variables. Ten old (62 to 73 years) and 10 young (21 to 32 years) healthy male volunteers were rigorously screened for cardiovascular disease and underwent comprehensive Doppler echocardiography, radionuclide ventriculography and invasive measurements of right heart and left atrial pressures. There were no differences between the two groups in the physiologic variables of left ventricular mass, volumes, ejection fraction, end-systolic wall stress, left atrial size, heart rate and right atrial, pulmonary artery, pulmonary capillary wedge and systemic arterial pressures. However, there were marked differences in Doppler left ventricular filling indexes. Compared with the young group, the old group had reduced peak early diastolic flow velocity (56 +/- 13 vs. 82 +/- 12 cm/s, p = 0.0002) and increased atrial diastolic flow velocity (59 +/- 14 vs. 43 +/- 10 cm/s, p = 0.009) and had a peak atrial/early flow velocity (A/E) ratio twice that of the young group (1.09 +/- 0.29 vs. 0.54 +/- 0.15, p less than 0.0001). Similar results were obtained for the time-velocity integrals of the peaks. Subjects in the old group also had a markedly reduced peak filling rate (274 +/- 62 vs. 448 +/- 152 ml/s, p = 0.004). In univariate and multivariate regression analyses, peak early and atrial flow velocities were not related to any of the physiologic variables measured once age was accounted for, although peak filling rate, a volumetric measure flow, was related to body surface area as well as age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Intravascular ultrasound assessment of the renal artery.

OBJECTIVE: To determine the feasibility and diagnostic value of catheter-based intravascular ultrasound imaging compared with angiography for visualizing renal artery structure. DESIGN: Renal artery images were obtained in patients with renal artery stenosis having percutaneous balloon angioplasty and in normal subjects by digital angiography and by a 20-MHz, mechanically driven, catheter-based, intravascular ultrasound imaging system. SETTING: A referral-based university hospital. PATIENTS: Four randomly selected normal subjects without known renal disease and four consecutive patients with known renal artery stenosis referred for percutaneous balloon angioplasty. INTERVENTIONS: Digital angiograms and intravascular ultrasound images of nine renal artery segments were obtained. In patients with renal artery stenosis, imaging was done before and after balloon angioplasty. MAIN RESULTS: Digital angiography and ultrasonography correlated closely in the determination of arterial lumen diameter (r = 0.81) and cross-sectional area (r = 0.83). However, ultrasonography provided structural information not shown by angiography. All normal arteries showed discrete intimal, medial, and adventitial wall layers by ultrasonography. In the five stenotic segments, angiography identified the cause of stenosis to be atherosclerosis in four patients and fibromuscular dysplasia in one patient. Ultrasound imaging, however, identified the disease process as atherosclerosis in three patients and as fibromuscular dysplasia in two patients. After renal angioplasty, ultrasonography identified three arterial dissections, only one of which was shown by angiography. CONCLUSIONS: These preliminary data indicate that catheter-based intravascular ultrasound imaging of the renal artery is feasible and correlates well with angiography in assessing renal artery size and also provides potentially important additional structural information that permits a better characterization of arterial pathology.

Aged↗
PubMed1991

Comparison of intravascular ultrasound, external ultrasound and digital angiography for evaluation of peripheral artery dimensions and morphology.

Validation of catheter-based intravascular ultrasound imaging has been based on comparisons with histology and digital angiography, each of which may have limitations in the assessment of arterial size and morphology. External, high-frequency ultrasound can accurately determine vessel dimensions and morphology and because, like ultravascular ultrasound, it also provides cross-sectional arterial ultrasound images, it may be a more appropriate technique for the in vivo comparison of arterial dimensions and morphology determined by intravascular ultrasound. Thus, intravascular ultrasound, external 2-dimensional ultrasound, Doppler color-flow imaging and digital angiography were compared for assessment of arterial dimensions and wall morphology at 29 femoral artery sites in 15 patients. Intravascular ultrasound and the other 3 imaging modalities correlated well in determination of lumen diameter (2-dimensional, r = 0.98, standard error of the estimate [SEE] = 0.14; Doppler color flow, r = 0.91, SEE = 1.11; angiography, r = 0.95, SEE = 0.91) and cross-sectional area (2-dimensional, r = 0.97, SEE = 0.04; Doppler color flow, r = 0.92, SEE = 0.14; angiography, r = 0.96, SEE = 0.08). However, lumen size measured by Doppler color flow was consistently smaller than that measured by the other 3 imaging modalities. Intravascular ultrasound detected arterial plaque at 15 sites, 5 of which were hypoechoic (soft) and 10 hyperechoic with distal shadowing (hard). Plaque was identified at 12 of 15 sites by Z-dimensional imaging (p = 0.30 vs intravascular ultrasound), but at only 6 of 15 sites by angiography (p = 0.003 vs intravascular ultrasound), only 1 of which was thought to be calcified plaque.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

The utility of echocardiography in the diagnostic strategy of postinfarction ventricular septal rupture: a comparison of two-dimensional echocardiography versus Doppler color flow imaging.

The diagnostic accuracy of Doppler color flow imaging in the diagnosis of postinfarction ventricular septal defects has not been established. In this study, 43 patients with unexplained hypotension or a new murmur in the periinfarct period were evaluated with conventional two-dimensional echocardiography and Doppler color flow imaging. The presence of a ventricular septal defect was confirmed by oximetry, ventriculography, operative repair, or autopsy in each case. Both two-dimensional and Doppler color flow imaging were 100% specific in excluding a ventricular septal defect. Doppler color flow imaging correctly identified the 12 confirmed ventricular septal defects in this study (100% sensitivity), whereas any combination of two-dimensional criteria only correctly identified seven (58% sensitive) (p less than 0.05). Doppler color flow imaging is superior to conventional two-dimensional imaging in the diagnosis of a postinfarction ventricular septal defect. In addition, Doppler color flow imaging localized the septal defect, and thus guided therapy and technique for repair. Carefully performed Doppler color flow examination can exclude or result in the rapid diagnosis of a ventricular septal defect, which eliminates the need for further time-consuming confirmatory testing.

Aged↗
PubMed1991

Effect of the degree of effort on exercise echocardiography for the detection of restenosis after coronary artery angioplasty.

To determine whether the accuracy of exercise echocardiography is affected by the degree of effort during exercise, we examined 101 patients who had 6 months earlier undergone successful coronary artery angioplasty, with resting and immediate postexercise echocardiography and same-day coronary angiography. A positive exercise echocardiographic response was defined as the development of a new or worsening wall motion abnormality postexercise, compared with resting wall motion. Significant coronary disease (greater than 50% diameter stenosis) was present in 48 patients, 38 of whom had single-vessel disease and 10 of whom had two-vessel disease. Exercise echocardiography correctly identified 32 patients with significant disease (sensitivity 67%) and 44 patients without significant disease (specificity 83%). The effect of the degree of exercise effort on the sensitivity and specificity of the test was evaluated by three criteria; (1) the percentage of maximum predicted heart rate (MHR), (2) the duration of exercise (DUR), and (3) the double product (DP). To determine the influence of the degree of effort upon sensitivity and specificity, the effort criteria were compared between patients with true positive (TP) tests to those with false negative tests (FN), and in patients with true negative (TN) tests compared with those with false positive (FP) tests. No significant differences were detected in MHR, DUR, or DP between TP versus FN patients or between TN versus FP patients. These results indicate that for symptom-limited exercise echocardiography in postangioplasty patients, neither sensitivity nor specificity is significantly affected by the degree of effort during exercise.

Angioplasty, Balloon, Coronary↗
PubMed1991

Exercise intolerance in patients with heart failure and preserved left ventricular systolic function: failure of the Frank-Starling mechanism.

Invasive cardiopulmonary exercise testing was performed in 7 patients who presented with congestive heart failure, normal left ventricular ejection fraction and no significant coronary or valvular heart disease and in 10 age-matched normal subjects. Compared with the normal subjects, patients demonstrates severe exercise intolerance with a 48% reduction in peak oxygen consumption (11.6 +/- 4.0 versus 22.7 +/- 6.1 ml/kg per min; p less than 0.001), primarily due to a 41% reduction in peak cardiac index (4.2 +/- 1.4 versus 7.1 +/- 1.1 liters/min per m2; p less than 0.001). In patients compared with normal subjects, peak left ventricular stroke volume index (34 +/- 9 versus 46 +/- 7 ml/min per m2; p less than 0.01) and end-diastolic volume index (56 +/- 14 versus 68 +/- 12 ml/min per m2; p less than 0.08) were reduced, whereas peak ejection fraction and end-systolic volume index were not different. In patients, the change in end-diastolic volume index during exercise correlated strongly with the change in stroke volume index (r = 0.97; p less than 0.0001) and cardiac index (r = 0.80; p less than 0.03). Pulmonary wedge pressure was markedly increased at peak exercise in patients compared with normal subjects (25.7 +/- 9.1 versus 7.1 +/- 4.4 mm Hg; p less than 0.0001). Patients demonstrated a shift of the left ventricular end-diastolic pressure-volume relation upward and to the left at rest. Increases in left ventricular filling pressure during exercise were not accompanied by increases in end-diastolic volume, indicating a limitation to left ventricular filling.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1991

Mechanisms of angioplasty in hemodialysis fistula stenoses evaluated by intravascular ultrasound.

Quantification of luminal dimensions and the mechanisms by which angioplasty (PTA) corrects non-atheroma venous fistula stenoses have been poorly studied. In 38 consecutive percutaneous balloon angioplasties of hemodialysis fistula stenoses, catheter-based, mechanically-rotated intravascular ultrasound (IVUS) images were obtained along with cineangiography. Images from 24 brachial vein, 11 central vein, 2 graft anastomoses, and 1 brachial artery were quantitatively and qualitatively evaluated. Semiautomated quantitative angiographic stenosis was 64 +/- 13% pre-PTA and reduced to 36 +/- 19% post-PTA (P less than 0.001). Post-PTA IVUS minimal lesion diameter and cross sectional area were 5.7 +/- 1.5 mm and 2.9 +/- 1.5 mm2, respectively. With IVUS, mechanisms observed were: vessel dissection in 16 (42%), arterial stretch (defined as vessel diameter: balloon diameter ratio = 0.75 to 1.0) in 19 (50%), and elastic recoil (defined as vessel diameter: balloon diameter ratio less than 0.75) in 19 (50%). Compared to angiography, morphologic information provided by IVUS were plaque composition (hard 11%, soft 89%), plaque topography (eccentric 94%, concentric 6%), thrombus (IVUS: N = 6 vs. angio: N = 1), dissection (IVUS: N = 16 vs. angio: N = 1). Thus, IVUS can evaluate lesion morphology and define luminal dimensions after angioplasty. Mechanisms of successful angioplasty of hemodialysis fistula stenosis occur primarily by vessel stretching and dissection, and significant post-PTA narrowing is due to elastic recoil.

Adult↗
PubMed1991

Intraoperative transesophageal Doppler color flow imaging used to guide patient selection and operative treatment of ischemic mitral regurgitation.

BACKGROUND: Intraoperative transesophageal Doppler color flow imaging (TDCF) affords the opportunity to assess mitral valve competency immediately before and after cardiopulmonary bypass (CPB). The purpose of this study was to assess the utility of TDCF to assist in the selection and operative treatment of ischemic mitral regurgitation (MR). METHODS AND RESULTS: Two hundred forty-six patients undergoing surgery for ischemic heart disease were prospectively studied. All had preoperative cardiac catheterization. Catheterization and pre-CPB TDCF were discordant in their estimation of MR in 112 patients (46%). Compared with patients in whom both techniques agreed in estimation of MR, patients with discordance in MR were more likely to have had unstable clinical syndromes at the time of catheterization (79% versus 40%, p less than 0.05) or to have received thrombolytics (16% versus 8%, p less than 0.05). Pre-CPB TDCF resulted in a change in the operative plan with respect to the mitral valve in 27 patients (11%). Because less MR was found by TDCF than catheterization, 22 patients had only coronary bypass grafting when combined coronary bypass and mitral valve surgery had been planned. Because more MR was found by TDCF than catheterization, five patients had combined coronary bypass and mitral valve surgery when coronary bypass alone had been planned. Unsatisfactory results noted by TDCF following mitral valve surgery in five patients resulted in immediate corrective surgery. Cox regression analysis identified residual MR at the completion of surgery to be an important predictor of survival (chi 2 = 21.4) after surgery--more important than patient age (chi 2 = 8.3) or left ventricular ejection fraction (chi 2 = 5.3). CONCLUSIONS: These results indicate that TDCF is useful in guiding patient selection and operative treatment of ischemic MR and that in such patients, intraoperative TDCF should be performed routinely.

Adult↗
PubMed1991

Rapid and accurate diagnosis of pulmonary emboli in a canine model using intravascular ultrasound imaging.

We utilized intravascular ultrasound (IVUS) imaging in a canine pulmonary embolism model to visualize experimental emboli. The images obtained were compared with those obtained by single-plane pulmonary arteriography in each of six animals. The vessel lumen appeared patent by both methods prior to injection of autologous clot. After thrombi were injected, the vessels were again imaged using both techniques. Intravascular ultrasound was 100 percent sensitive in detecting emboli, and visualization was always rapid. There were no complications. It appears that IVUS imaging is a sensitive method for documenting the presence of clot in a canine pulmonary embolism model.

Animals↗