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Biomedical subjects

M B Harding

Publications and source records attributed to M B Harding.

10 recordsLinked to original sources
PubMed1992

Left ventricular filling and ventricular diastolic performance after percutaneous balloon mitral valvotomy.

The time course of left ventricular (LV) filling and LV diastolic performance were examined in 27 consecutive patients in sinus rhythm before and acutely after balloon mitral valvotomy (BMV). The mitral valve area acutely increased from 1.1 +/- 0.3 to 2.1 +/- 0.8 cm2. Simultaneous pressure-volume data were obtained using digital subtraction left ventriculography and LV micromanometer pressure before and 10 minutes after BMV. The time constant of LV isovolumic relaxation was unchanged after BMV (50 +/- 10 ms before BMV vs 47 +/- 13 ms after BMV). In addition, values before and after BMV for LV end-diastolic volume (123 +/- 29 vs 125 +/- 36 ml), end-diastolic pressure (11 +/- 4 vs 12 +/- 4 mm Hg) and diastolic filling time (337 +/- 126 vs 338 +/- 152 ms) were not altered by the procedure. After BMV the peak diastolic filling rate (403 +/- 143 vs 469 +/- 302 ml/s) was maintained despite a 36% reduction in left atrial filling pressure. There was a trend toward earlier occurrence of the peak filling rate (196 +/- 127 vs 146 +/- 148 ms, p = 0.08). The percentage of diastolic filling in the first third of diastole, however, was similar (42 +/- 9 vs 48 +/- 16%) before and after the procedure. Thus, the time course of LV filling is not significantly altered acutely after BMV, but is maintained at reduced left atrial filling pressure. Neither LV relaxation or LV chamber compliance are altered acutely after BMV.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Quantitative and qualitative coronary angiographic analysis: review of methods, utility, and limitations.

Coronary angiography continues to be the pivotal study in the diagnosis and treatment of ischemic cardiac disease. Although angiographic equipment and imaging techniques have advanced over the past three decades, the analysis of coronary angiograms, by visual estimated percent diameter stenosis, has remained unchanged in most clinical catheterization laboratories. Rapid, computerized angiographic analysis systems are now available that remedy the inherent imprecision and inaccuracies plaguing visual coronary analysis. Despite its advantages, successful QCA is quite dependent on meticulous attention to radiographic and angiographic technique, even more so than with visual analysis. Although the available QCA systems can reproducibly and accurately define the site and degree of coronary stenosis, they cannot routinely determine whether an obstruction is flow limiting. Several methods, some based on extrapolations of quantitative measures alone, and others based on digital subtraction angiography, have been developed to determine the physiologic impact of a given coronary lesion. Recent observations have demonstrated, however, that even if the physiologic consequences of an obstruction are known, the prognosis of the lesion over time cannot be predicted. The qualitative, morphologic characteristics of a lesion are as, or more, important than the quantitative lesion attributes in determining an atheroma's behavior and stability, and hence, qualitative descriptors should be incorporated into QCA analyses. Although not currently available, future QCA systems will provide, by automated analysis, reproducible and accurate measures of absolute obstruction, physiologic data describing the flow limiting characteristics of a lesion, and qualitative, morphologic lesion descriptors. Implementation of these systems should provide more consistent and accurate prognostic and pathophysiologic information, thereby helping to refine and more effectively direct therapeutic interventions in coronary artery disease.

Algorithms↗
PubMed1992

Use of balloon occlusion to improve visualization of anomalous pulmonary venous return in an adult with cor triatriatum.

Cor triatriatum, although rare in adults, is often associated with anomalous pulmonary venous return. Accurate diagnosis of the pulmonary venous return and its anatomic connections is essential in planning proper surgical correction. This case illustrates the advantage of selective pulmonary artery angiography in obtaining accurate detail of the pulmonary venous anatomy from digital subtraction levophase images. Selective right and left pulmonary angiography was performed using a balloon catheter to simultaneously occlude the opposite pulmonary artery. This technique was well tolerated and greatly enhanced visualization of the anomalous pulmonary venous connections, allowing proper planning for corrective surgery.

Angiography, Digital Subtraction↗
PubMed1992

Ergonovine maleate testing during cardiac catheterization: a 10-year perspective in 3,447 patients without significant coronary artery disease or Prinzmetal's variant angina.

The utility of ergonovine testing for coronary artery spasm was assessed in 3,447 patients with angiographically insignificant (less than 50% diameter stenosis) or no coronary artery disease. No patients clinically had Prinzmetal's variant angina. Overall, 4% had a positive ergonovine test result, defined by spasm causing greater than or equal to 75% focal stenosis. Complications related to ergonovine use occurred in 11 patients (0.03%). In a training sample of 1,136 patients (studied between 1980 and 1984), two independent predictors of spasm were found by using multivariate analysis: the amount of visible coronary artery disease on the coronary angiogram (p less than 0.0001) and a smoking history (p = 0.001). A model to predict spasm based on these variables was validated in a test group of 2,311 patients who received ergonovine from 1985 to 1989. This model allowed the identification of a subset of 400 patients in the validation sample who had a 10% positive test rate compared with a 2% positive test rate in the remaining patients. These results should permit clinicians who use provocative testing in the catheterization laboratory to reserve testing for the subset of this group of patients most likely to have abnormal findings.

Angina Pectoris, Variant↗
PubMed1992

Critical mitral stenosis causing ischemic hepatic failure. Successful treatment by percutaneous balloon mitral valvotomy.

We report a 52-year-old patient with severe mitral stenosis who developed new onset atrial fibrillation, low output congestive heart failure and fulminant ischemic hepatic failure with subsequent severe coagulopathy. Percutaneous mitral valvotomy resulted in dramatic clinical improvement with complete resolution of liver function. This case illustrates the potential life-saving role for percutaneous balloon mitral valvotomy in treating critically ill patients who are unable to undergo thoracotomy due to coexisting medical illness.

Atrial Fibrillation↗
PubMed1992

Renal artery stenosis: prevalence and associated risk factors in patients undergoing routine cardiac catheterization.

The purposes of this study were to determine the prevalence of angiographically significant renal artery stenosis in a patient population referred for diagnostic cardiac catheterization and to develop a model that predicts the highest-risk subset of patients who have significant renal artery narrowing. A prospective validation cohort study was undertaken in a referral-based university hospital. After left ventriculography, abdominal aortography was performed to screen for the presence of renal artery disease. A convenience sample of 1,302 of 1,651 consecutive patients undergoing diagnostic cardiac catheterization were enrolled in the study. Of the 1,302 abdominal aortograms performed, 1,235 (95%) were deemed of adequate quality for the evaluation of renal artery anatomy. Renal artery disease was identified in 30% of the patients. Insignificant renal artery stenosis was found in 187 (15%) and significant (greater than or equal to 50% diameter narrowing) stenosis was found in 188 (15%). Significant unilateral disease was present in 11%, and bilateral disease was present in 4%. By univariable and multivariable logistic regression analysis, the association of both clinically and catheterization-derived variables with renal artery disease was assessed. Multivariable predictors included age, severity of coronary artery disease, congestive heart failure, female gender, and peripheral vascular disease. Hypertension was not an associated variable. These data reveal the previously undetected high prevalence of renal artery disease in patients undergoing cardiac catheterization and provide clinical and angiographic features that assist in predicting its presence.

Aged↗
PubMed1990

A rapid, effective technique for retrograde crossing of valvular aortic stenosis using standard coronary catheters.

Retrograde crossing of valvular aortic stenosis can be challenging even to experienced angiographers. In 446 of 447 consecutive patients with aortic stenosis catheterized during the past 3 years, a technique using a standard Judkins right coronary catheter and a floppy straight tipped guide wire was successful in rapidly and efficiently crossing these pathologically distorted valves in retrograde fashion. Once the valve was crossed, the coronary catheter was replaced with a pigtail catheter for pressure and ventriculography. The majority of these valves required less than 2 min to cross using this technique. This method is valuable in limiting the time required for catheterization, thus helping to reduce procedure related morbidity in these oftimes critically ill patients.

Aged↗