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Biomedical subjects

K H Sheikh

Publications and source records attributed to K H Sheikh.

At least 37 records · Page 2Linked to original sources
PubMed1990

Balloon angioplasty of coarctation of the aorta evaluated with intravascular ultrasound imaging.

Intravascular ultrasound images were employed to evaluate aortic coarctation before and after balloon angioplasty. Measurements obtained with use of an ultrasound imaging catheter correlated well with measurements made with digital aortography, both in the area of coarctation and in areas proximal and distal to it. The intravascular ultrasound images dramatically revealed dissection of the aortic wall and an intimal flap that was not appreciated on cineaortography or digital subtraction angiography. Intravascular ultrasound imaging may yield important morphologic information unavailable by other imaging techniques. Such information may allow more precise definition of the results of intravascular procedures and improve understanding of lesion characteristics predictive of a successful outcome.

Adult↗
PubMed1990

Relation of quantitative coronary lesion measurements to the development of exercise-induced ischemia assessed by exercise echocardiography.

To assess the relation of quantitative measures of coronary stenoses to the development of exercise-induced regional wall motion abnormalities, 34 patients with isolated, single vessel coronary artery lesions and normal wall motion at rest underwent exercise echocardiography and quantitative angiography on the same day. Although all 11 patients with a visually estimated stenosis greater than or equal to 75% had an ischemic response and 10 (91%) of 11 patients with a less than or equal to 25% visually estimated stenosis had a normal response by exercise echocardiography, among 12 patients with a visually estimated stenosis of 50%, 6 (50%) had an ischemic response and 6 (50%) had a normal exercise echocardiogram. Quantitative measurements of stenosis severity distinguished patients with ischemic (group 1) from normal (group 2) exercise echocardiographic responses as follows: minimal luminal diameter (mm), group 1 1.0 +/- 0.4 versus group 2 1.7 +/- 0.4, p less than 0.0001; minimal cross-sectional area (mm2), group 1 0.9 +/- 0.6 versus group 2 2.5 +/- 1.1, p less than 0.0001; percent diameter stenosis, group 1 68.3 +/- 14.2 versus group 2 42.2 +/- 12.1, p less than 0.0001; and percent area stenosis, group 1 87.5 +/- 7.8 versus group 2 64.8 +/- 15.9, p less than 0.0001. These data validate the utility of exercise echocardiography by demonstrating that 1) coronary stenosis severity measured by quantitative angiography is closely related to wall motion abnormalities detected by exercise echocardiography, and 2) exercise echocardiography can be used as a noninvasive means to assess the physiologic significance of coronary artery lesions.

Adult↗
PubMed1990

Intravascular ultrasonography versus digital subtraction angiography: a human in vivo comparison of vessel size and morphology.

The accuracy of catheter-based intravascular ultrasonography to define luminal size in humans in vivo and its sensitivity to describe lesion morphology have not been previously reported. Vessel diameter, cross-sectional area and lesion characteristics assessed by digital subtraction angiography and intravascular ultrasonography (20 MHz) were compared in 86 human arterial segments. The same arterial segments were imaged and analyzed by digital subtraction angiography and intravascular ultrasonography at 49 femoral, 3 renal, 5 iliac, 7 pulmonary and 22 aortic sites. Digital subtraction angiographic diameter and area were determined geometrically by an automated algorithm. Intravascular ultrasonographic diameter and area were determined by planimetry. Linear correlation for diameter by the two techniques was 0.97, standard error of the estimate (SEE) = 1.83 mm, and for cross-sectional area it was 0.95, SEE = 0.65 cm2. Intravascular ultrasonography identified 24 sites in which plaque was present; 11 (46%) of these segments appeared normal by digital subtraction angiography. Conversely, digital subtraction angiography demonstrated irregularities in 18 segments of which 5 (28%) appeared normal by intravascular ultrasonography. These data indicate an excellent correlation between intravascular ultrasonography and digital subtraction angiography for in vivo assessment of human arterial dimensions in normal and minimally diseased segments. However, intravascular ultrasonography is more likely to identify atherosclerotic plaque that may be angiographically "silent."

Angiography, Digital Subtraction↗
PubMed1990

Augmentation of mortality risk discriminating power of left ventricular ejection fraction by measures of nonuniformity in systolic emptying on radionuclide ventriculography.

Employing equilibrium-gated radionuclide ventriculography in the left anterior oblique view, six geometric models and five mathematic coefficients of nonuniformity in regional left ventricular emptying were tested for their relative mortality risk-stratifying power and capacity to augment the risk-discriminating potency of the continuous and dichotomized global ejection fraction. Radionuclide ventriculography was performed an average of 7.6 days after acute myocardial infarction. All geometric models significantly separated 20 normal subjects from 137 patients with recent infarction (p less than 0.001). Cumulative mortality data demonstrated that significant independent univariate dichotomizing potency and augmentation of the mortality risk-discriminating power of the global ejection fraction were provided by models of regional emptying that 1) conformed to coronary artery perfusion areas, 2) encompassed total ventricular counts, 3) expressed variability in regional relative to global ejection fraction, and 4) simulated a pattern of emptying directed toward the center of geometry of the left ventricle. The combination of a four quadrant geometric model with axes drawn 45 degrees above the horizontal and a coefficient of variation calculated as square root of sigma(GEF - REF)2/4 x 100/GEF (where GEF = global ejection fraction and REF = regional ejection fraction) proved to be optimal. This coefficient averaged 12.2% in normal subjects and 32.2% in patients with recent acute myocardial infarction (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

The utility of transesophageal echocardiography and Doppler color flow imaging in patients undergoing cardiac valve surgery.

To assess the value of intraoperative transesophageal echocardiography during cardiac valve surgery, 154 consecutive patients who had a valve operation in conjunction with pre- and postcardiopulmonary bypass transesophageal imaging were studied. Prebypass imaging yielded unsuspected findings that either assisted or changed the planned operation in 29 (19%) of the 154 patients. Imaging immediately after bypass revealed unsatisfactory operative results that necessitated immediate further surgery in 10 (6%) of the 154 patients. Postbypass left ventricular dysfunction, prompting administration of inotropic agents, was identified in 13 patients (8%). Transesophageal echocardiography proved most useful when both two-dimensional and Doppler color flow imaging were employed in patients undergoing a mitral valve operation, where surgical decisions based on echocardiographic results were made in 26 (41%) of 64 cases. Postbypass echocardiographic findings identified patients at risk for an adverse postoperative outcome. Of 123 patients whose postbypass valve function was judged to be satisfactory, 18 (15%) had a major postoperative complication and 6 (5%) died, whereas of 7 patients with moderate residual valve dysfunction, 6 (86%) had a postoperative complication and 3 (43%) died (p less than 0.05 for both). Likewise, of 131 patients with preserved postbypass left ventricular function, 12 (9%) had a major complication and 7 (5%) died, whereas of 23 patients with reduced ventricular function, 17 (73%) had a postoperative complication and 6 (26%) died (p less than 0.05 for both). These data indicate that intraoperative transesophageal echocardiography is useful in formulating the surgical plan, assessing immediate operative results and identifying patients with unsatisfactory results who are at increased risk for postoperative complications.

Cardiopulmonary Bypass↗
PubMed1990

Changes in left ventricular diastolic performance after aortic balloon valvuloplasty: acute and late effects.

To evaluate acute and follow-up changes in left ventricular diastolic performance, simultaneous digital left ventriculography and micromanometry were performed in 49 patients undergoing aortic balloon valvuloplasty. All patients improved symptomatically after valvuloplasty, and 26 returned 6.3 +/- 1.5 months later for follow-up catheterization. Immediately after valvuloplasty, aortic valve area increased (before 0.5 +/- 0.2 versus after 0.8 +/- 0.2 cm2, p less than 0.01), cardiac output (before 4.3 +/- 1.2 versus after 4.4 +/- 1.3 liters/min) and ejection fraction (before 51 +/- 18% versus after 52 +/- 17%) did not change and diastolic indexes worsened, signified by a decrease in peak filling rate (before 247 +/- 80 versus after 226 +/- 78 ml/s, p less than 0.01) and increase in the time constant of isovolumetric relaxation (tau) (before 78 +/- 29 versus after 96 +/- 40 ms, p less than 0.01) and the modulus of chamber stiffness (before 0.107 +/- 0.071 versus after 0.141 +/- 0.083, p less than 0.01). At follow-up catheterization, 16 patients continued to have symptomatic improvement (group 1) and 10 had recurrence of symptoms (group 2). Aortic valve area, cardiac output and ejection fraction at follow-up catheterization in both groups were similar and unchanged from values before valvuloplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Interventional applications of intravascular ultrasound imaging: initial experience and future perspectives.

Intravascular ultrasound imaging offers the potential to provide more detailed information about vessel and lesion morphology and physiology than is currently available from angiography. The greatest impact of intravascular ultrasound upon clinical decisions may be in the area of cardiac and vascular interventions. To evaluate the utility of intravascular ultrasound, we prospectively studied 45 patients, 11 of whom underwent interventional procedures. Intravascular ultrasound imaging was performed before and after interventions using a 20 MHz, mechanically rotating transducer on either 6.5 Fr or 8.0 Fr catheter systems. Interventions included seven peripheral vessel balloon angioplasties (Femoral artery-two, Renal artery-two, Arteriovenous fistula-two, Aortic coarctation-one), two Femoral artery rotational atherectomies, and two balloon valvuloplasties (Pulmonic valve-1, Mitral valve-1). Intravascular ultrasound and digital angiography provided similar information about vessel size. However, morphological information about the vessel wall, plaque composition, plaque topography, luminal thrombus, and vessel dissections was better appreciated by intravascular ultrasound. Intravascular ultrasound was determined to have provided unique and clinically useful information in 10/11 (91%) interventions. These preliminary data illustrate the potential value of intravascular ultrasound for the evaluation of the vascular system and in particular its value in interventional procedures.

Angioplasty, Balloon↗
PubMed1990

Use of Doppler echocardiography and amyl nitrite inhalation to characterize left ventricular outflow obstruction in hypertrophic cardiomyopathy.

The presence of left ventricular outflow tract obstruction (LVOTO) of either a resting or dynamic nature may have important therapeutic and prognostic implications in patients with hypertrophic cardiomyopathy (HCM). Doppler echocardiograms combined with amyl nitrite (Amyl) inhalation were performed in 333 consecutive patients referred for suspected HCM to diagnose and categorize the nature and severity of LVOTO. Hypertrophic cardiomyopathy was present by 2-D and M-mode criteria in 145/333 (44 percent) patients. Normal limits of resting and post-Amyl continuous wave Doppler peak left ventricular outflow tract velocities were established in 15 subjects with completely normal 2-D and Doppler echocardiograms. Based on these criteria, of the 145 patients with HCM, 63 (43 percent) were classified as having resting LVOTO, peak velocity 4.2 +/- 1.3 m/s. Among 82 patients with HCM without resting LVOTO, 47 (57 percent) received Amyl. Latent LVOTO was provoked in 25/47 (53 percent), peak post-Amyl velocity 4.5 +/- 1.2 m/s. The remaining 22 (47 percent) had nonobstructive HCM, as indicated by no significant increase in post-Amyl velocity. Among a total 62 subjects receiving Amyl, none experienced serious morbidity or mortality. Doppler echocardiography, in conjunction with Amyl inhalation in selected patients, is a useful noninvasive method to diagnose and categorize patients with HCM according to the nature and severity of LVOTO.

Aged↗
PubMed1990

Routine use of intraoperative epicardial echocardiography and Doppler color flow imaging to guide and evaluate repair of congenital heart lesions. A prospective study.

Routine epicardial two-dimensional echocardiography, Doppler, and Doppler color flow imaging studies were performed before and after cardiopulmonary bypass in 328 patients undergoing operations for congenital heart disease. Ages ranged from 1 day to 59 years (mean 5.9 years); the smallest patient was 1.8 kg. Complete examinations were conducted in 3.6 +/- 1.7 minutes. Prebypass examinations demonstrated previously unappreciated details of anatomy in 60 patients (18%), which did not relate to whether catheterization had been performed, and they were believed to play a role in surgical planning in 143 patients (44%). Discovery of previously unrecognized features of anatomy increased the impact of echo-Doppler color flow imaging on operative planning by 2.5 times. After bypass, echo-Doppler color flow imaging disclosed unsuspected residual defects in 22 patients (7%) who were doing well clinically and enabled an attempt at immediate revision of the procedure. When ultimate clinical outcome was compared to postbypass findings of echo-Doppler color flow imaging, the presence of a residual defect, right or left ventricular dysfunction, or any concern with the heart by echo-Doppler color flow imaging appeared to serve as a predictor of unfavorable outcome (p less than 0.001 for each when compared with absence of these difficulties). Thus routine intraoperative echo-Doppler color flow imaging is useful in aiding the planning, conduct, and assessment of results in operations for congenital heart disease.

Cardiopulmonary Bypass↗
PubMed1989

Doppler left ventricular diastolic filling abnormalities in aortic stenosis and their relation to hemodynamic parameters.

Doppler mitral flow indexes and their relation to invasively measured hemodynamic diastolic indexes were assessed in 13 patients with isolated aortic stenosis (AS), and compared to Doppler indexes in 10 normal subjects matched for age, heart rate, left ventricular (LV) ejection fraction and LV load. Patients with AS showed no difference in Doppler early filling (E) indexes, but demonstrated greater Doppler atrial filling (A) indexes in comparison to normal subjects: atrial velocity (89 +/- 31 vs 56 +/- 7 cm/s), atrial integral (11.4 +/- 4.8 vs 5.7 +/- 1.6 cm), A/E velocity (1.69 +/- 0.89 vs 1.06 +/- 0.26) and A/E integral (3.53 +/- 6.64 vs 0.81 +/- 0.27) (all p less than 0.05). Doppler indexes in patients with AS did not correlate with hemodynamic indexes of LV relaxation or chamber stiffness. Significant correlations were observed between Doppler and angiographic peak filling rates (r = 0.70) and between Doppler atrial filling velocity and LV end-diastolic volume (r = -0.66), LV end-diastolic pressure (r = -0.48) and LV ejection fraction (r = 0.53) (all p less than 0.05). These data indicate that, compared to matched normal subjects, most patients with AS have an increased atrial contribution to LV filling. However, in patients with decreased LV function, atrial function may also be depressed, as indicated by a decreased atrial contribution to LV filling, resulting in "normalization" of the Doppler mitral flow pattern.

Aged↗
PubMed1989

Utility of Doppler color flow imaging for identification of femoral arterial complications of cardiac catheterization.

Doppler color flow and two-dimensional ultrasonographic images of the femoral region were obtained in 25 patients referred for suspected vascular complications of cardiac catheterization. Five patients had normal findings, while 23 abnormalities were noted in 20 patients, including seven femoral arteriovenous fistulae, 12 femoral pseudoaneurysms, and two patients with both femoral arteriovenous fistulas and pseudoaneurysms. Operation confirmed the abnormalities diagnosed by color flow examination in 15 of 20 patients. Three patients refused operation and one was not felt to be a surgical candidate due to high anesthetic risk. One patient died preoperatively and postmortem examination confirmed the color flow diagnosis. Etiologies of the arterial complications included percutaneous aortic valvuloplasty (6), coronary angioplasty (4), and arterial or both arterial and venous catheterization (10). Doppler color flow imaging is a reliable technique for identification of vascular complications following catheterization procedures.

Aged↗
PubMed1989

The use of intraoperative echo with Doppler color flow imaging to predict outcome after repair of congenital cardiac defects.

Surgical repair of congenital cardiac defects (CCD) has undergone a remarkable evolution in the past decade. Major defects are now often completely corrected in early infancy with continually improving rates of survival. It has become clear that the next major focus will be improvements in the long-term quality of life and this has promoted many innovations in surgical technique and approach. One advance is the use of intraoperative echo with Doppler color flow imaging (echo-DCFI) to evaluate the exactness of operative repair. Aside from anecdotal reports, very little information is available regarding the interpretation of images produced by this technology in the operating room. Furthermore there have been no studies addressing the predictive value of intraoperative echo-DCFI findings with respect to outcome for patients undergoing repair of CCD. The prospective data obtained by following the course of 273 patients receiving intraoperative echo-DCFI has been reviewed after repair of a variety of CCD (age range, 1 to 53 years; mean 5.3 years; smallest patient, 1.8 kg). Forty-seven patients (17%) had initially unacceptable results, by echo, at the completion of their repair. Eighteen of these patients (7% of entire series) had no clinical problems and the defects were discernible only by echo. Twenty-six patients with initially unacceptable results had their repairs revised in the operating room and left with an acceptable result by echo. Twenty-one patients were allowed to leave the operating room with echo-discernible defects. Follow-up of these patients demonstrated a significantly higher (p less than 0.006) rate of reoperation (42% vs. 3%) and of early death (29% vs. 10%) for those patients whose defects were left unrepaired compared to those whose problems were corrected before leaving the operating room. Sixty-eight patients (25%) had some alteration of ventricular function (compared to their prebypass evaluation) at the completion of their repair. Regardless of whether the dysfunction was limited to the right ventricle, left ventricle, or was biventricular, patients in this group had a significantly higher incidence (p less than 0.004) of early, but not late, death compared to patients without alteration of ventricular function (35% vs. 4%). Patients who left the operating room with no problems of concern by echo-DCFI had a greater than 90% likelihood of a long-term acceptable outcome compared to patients who had any problem of concern (residual defect, anatomic or technical imperfection, ventricular dysfunction, and so on) whose long-term likelihood of an acceptable outcome approached 50% (p less than 0.0125).(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1989

Epiglottitis--an increasing problem for adults.

In a 2-year period, 9 adults were admitted to hospital with acute epiglottitis confirmed by direct laryngoscopy or lateral neck radiograph, or both. The mean age was 53 +/- 14 years, with acute epiglottitis occurring in 89% during the months of September to March. Intubation was required in 4 patients. The duration of symptoms was 7.8 +/- 2.4 hours for intubated patients versus 18.8 +/- 8.9 hours for those not intubated. For 6 patients an incorrect diagnosis was made on their first presentation. All 8 patients having laryngoscopy had typical findings, and none had respiratory obstruction precipitated by the procedure. In 5 patients blood cultures were positive, 4 for Hemophilus influenzae type b, and 1 for Streptococcus pneumoniae. In 2 patients the H influenzae was ampicillin-resistant. All patients recovered after receiving parenteral steroid therapy and appropriate antibiotics.

Adult↗