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Biomedical subjects

W J French

Publications and source records attributed to W J French.

At least 55 records · Page 3Linked to original sources
PubMed1990

Relationship between right atrial and mixed venous oxygen saturation and heart rate during exercise in normal subjects and patients with cardiac disease.

An ideal sensing variable for use in rate responsive pacemakers should measure a physiological parameter that closely correlates with heart rate during various activities in a diverse group of subjects. Nineteen patients, 12 normal and 7 patients with heart disease, were studied to assess the relationship between mixed venous oxygen saturation and heart rate. In patients with heart disease right atrial oxygen saturation and heart rate were also compared. Each subject underwent pulmonary artery catheterization and performed seated cycle ergometer exercise. Gas exchange and heart rate were measured continuously and blood sampled at frequent intervals. Normal patients were studied at rest and during steady-state exercise (mean work rate 149 watts). Patients were studied at rest, steady-state exercise (mean work rate 37 watts), and during incremental exercise (5-10 watts/min) to tolerance. There were 248 paired right atrial or mixed venous oxygen saturation/heart rate observations obtained. Changes in mixed venous oxygen saturation and heart rate were not substantially altered by fitness or cardiac disease. Rate responsive pacemakers sensing changes in oxygen saturation may be a superior sensing variable for both normal and patients with heart disease.

Adult↗
PubMed1989

Inadvertent Swan-Ganz catheter placement in the left pericardiophrenic vein.

Placement of flow-directed Swan-Ganz catheters without fluoroscopic guidance occasionally results in placement in positions other than the pulmonary artery. In the case presented, the inadvertent placement of such a catheter into the left pericardiophrenic vein was probably facilitated by distortion of the right heart and systemic venous anatomy.

Aged↗
PubMed1989

Verapamil induced ventricular hypertrophy in conscious dogs.

Verapamil is used clinically in the treatment of various cardiac diseases including hypertrophic cardiomyopathy. Its long term effects on ventricular mass are not well known. In 11 conscious dogs heart rate, aortic and left ventricular pressures, cardiac output, a methoxamine induced stress ventricular function test and left ventriculography were performed. These variables were measured prior to and following a mean 7.2 month infusion of verapamil at 0.005 or 0.01 mg.kg-1.min-1 using a subcutaneously implanted pump. Resting haemodynamic variables and left ventricular ejection fraction [60(SD 6) v 55(6)%] were unchanged between baseline and chronic verapamil studies, but the slope of the methoxamine induced stress ventricular function test decreased from 3.9(0.8) to 2.1 (1.3). After verapamil was discontinued the mean slope of the stress ventricular function test returned to the baseline 4.0(1.7). Total ventricular weight increased 22% from 176.1(17.5) g.m-2 in controls to 215.6(29.5) g.m-2 (p less than 0.01) in the verapamil animals. The right ventricular weight increased 25% from 46(5.9) to 57.6(9.1) g.m-2 (p less than 0.01); the septum weight increased 26% from 42.5(4.1) to 53.7(7.2) g.m-2 (p less than 0.001); and the left ventricular free wall weight increased 19% from 87.4(9.8) to 103.9(15.7) g.m-2 (p less than 0.01). The increase in ventricular weights was not due to fibrosis or oedema since hydroxyproline contents and wet/dry ratios were not increased. In conclusion, a chronic infusion of verapamil in conscious dogs caused no change in resting haemodynamic variables but produced reversible depression of stress ventricular function and biventricular and septal hypertrophy.

Animals↗
PubMed1989

Physiological importance of different atrioventricular intervals to improved exercise performance in patients with dual chamber pacemakers.

To determine the importance of different atrioventricular intervals during exercise in patients with dual chamber pacemakers, seven patients with complete heart block and sinus rhythm were exercised in different pacing modes and atrioventricular intervals: (a) ventricular inhibited (VVI) pacing with no synchronous atrial augmentation or rate responsiveness; (b) atrial synchronous ventricular or DDD pacing with a short mean (SD) atrioventricular interval of 66 (4) ms; and (c) DDD pacing with a long atrioventricular interval of 168 (12) ms. Pacing with a short or long atrioventricular interval gave similar maximum heart rates, oxygen uptake at the anaerobic threshold, end tidal pressure of carbon dioxide or oxygen pulse (a measure of stroke volume). Pacing with either a short or long atrioventricular interval produced a significantly higher oxygen consumption and anaerobic threshold and less lactate production than VVI pacing. During exercise a short atrioventricular interval does not provide a better cardiopulmonary performance than a long atrioventricular interval.

Adult↗
PubMed1989

Chest trauma and subvalvular left ventricular aneurysms.

Two patients were discovered to have pulsatile saccular lesions at the base of the left ventricle and mitral regurgitation following blunt trauma to the chest. These aneurysms resembled annular subvalvular aneurysms which have previously been reported as congenital defects in African blacks and as acquired lesions following endocarditis or mitral valve replacement. The first patient had two aneurysms, while the second had an aneurysm in continuity with a traumatic ventricular septal defect. These aneurysms were detected by echocardiography and magnetic resonance imaging and should be sought in patients who develop valvar regurgitation following chest trauma.

Adult↗
PubMed1989

Simultaneous technetium-99m MIBI angiography and myocardial perfusion imaging.

Resting first-pass radionuclide angiography (FPRNA) was performed with the myocardial perfusion agent technetium-99m MIBI. In 27 patients, it was compared with technetium-99m diethylenetriamine pentaacetic acid FPRNA. A significant correlation was present in left (r = 0.93, p less than 0.001) as well as right (r = 0.92, p less than 0.001) ventricular ejection fraction measured with both radiopharmaceuticals. In 13 patients, MIBI derived segmental wall motion was compared with contrast ventriculography. A high correlation was present (p less than 0.001), and qualitative agreement was found in 38/52 segments. In 19 patients with myocardial infarction a significant correlation was present between MIBI segmental wall motion and perfusion scores (p less than 0.001). In ten patients with a history of myocardial infarction, 18 myocardial segments demonstrated diseased coronary vessels and impaired wall motion at contrast angiography. These segments were all identified by the MIBI wall motion and perfusion study. We conclude that MIBI is a promising agent for simultaneous evaluation of cardiac function and myocardial perfusion at rest.

Angiography↗
PubMed1989

Direct cocaine cardiotoxicity demonstrated by endomyocardial biopsy.

The morbidity and mortality associated with cocaine abuse has markedly increased in recent years. Although several articles indicate a possible connection of cocaine with coronary spasm and acute myocardial infarction, this study in seven patients with a history of cocaine abuse, who underwent endomyocardial biopsy, suggests that cocaine may cause direct toxicity to the myocardium. Myocardial specimens from five of seven patients showed multifocal myocyte necrosis, of which two specimens revealed focal myocarditis, while three specimens had changes consistent with dilated cardiomyopathy. Ultrastructurally, extensive loss of myofibrils and sarcoplasmic vacuolization were observed. It is postulated that the pathogenesis of acute cocaine-induced toxicity is direct destruction of myofibrils resulting in myocyte necrosis and that these changes may or may not be associated with interstitial inflammatory cell infiltrates. Long-term abuse of cocaine may lead to interstitial fibrosis and eventually congestive heart failure.

Adult↗
PubMed1988

Accuracy of left atrial and pulmonary artery wedge pressure in pure mitral regurgitation in predicting left ventricular end-diastolic pressure.

In most clinical conditions pulmonary artery (PA) wedge pressure accurately reflects left ventricular (LV) end-diastolic pressure. In the presence of mitral regurgitation (MR), large V waves can distort PA wedge pressure and result in incorrect estimation of LV end-diastolic pressure. In 52 patients with MR simultaneous measurement of PA wedge pressure or left atrial pressure and LV end-diastolic pressure was recorded. Twenty-one (40%) patients had large V waves (V wave greater than A wave by greater than 10 mm Hg, group 1), and 31 (60%) patients had small V waves (group 2). Group 1 had significantly higher V waves than group 2 (46 +/- 3 vs 21 +/- 2 mm Hg, p less than 0.001). The LV end-diastolic pressure was similar in both groups (21 +/- 2 vs 19 +/- 2 mm Hg, difference not significant). The mean PA wedge or left atrial pressure in group 1 (26 +/- 2 mm Hg) overestimated LV end-diastolic pressure (21 +/- 2 mm Hg) by 30% (p less than 0.01), but the trough of the X descent (20 +/- 2 mm Hg) was similar to the LV end-diastolic pressure. In group 2 patients with small V waves the mean PA wedge pressure was not significantly different from the LV end-diastolic pressure (16 +/- 2 vs 19 +/- 2 mm Hg, p = 0.06), but the trough of the X descent (13 +/- 2 mm Hg) underestimated LV end-diastolic pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Percutaneous double-balloon angioplasty of a stenotic modified Fontan aortic homograft conduit.

A 28-year-old woman with pulmonary atresia underwent a modified Fontan procedure that utilized a valved aortic homograft; she developed stenosis of the distal anastomosis between the homograft and the pulmonary artery. Because of the increased risk of reoperation, balloon angioplasty of this stenotic lesion was performed successfully. In the subsequent 11 months she has remained asymptomatic. Balloon angioplasty was a successful alternative to reoperation in this patient.

Adult↗
PubMed1988

Physiological benefits of a pacemaker with dual chamber pacing at low heart rates and single chamber rate responsive pacing during exercise.

Dual chamber rate responsive pacing may be an ideal mode but may result in high current drain and premature battery depletion. To minimize battery drain during exercise, this study compared a combination pacing mode of DDD and ventricular rate responsive pacing (VVIR). Nine patients were studied who had complete heart block, sinus rhythm, DDD pacemakers, and a reduced mean left ventricular ejection fraction of 44%. Patients were exercised in DDD, VVIR, and a combination of DDD at low heart rates and VVIR at mean heart rates over 89 bpm. Blood pressure, heart rate, exercise duration, work rate, oxygen uptake, anaerobic threshold, and oxygen pulse were measured. There was no difference in symptoms or in mean cardiopulmonary function indices including exercise duration 10.7, 10.3, 10.3 minutes; heart rate 127, 133, 136 bpm; oxygen uptake 1.4, 1.5, 1.5 L/minute; or anaerobic threshold 5.6, 5.5, 5.7 minutes (p greater than 0.05) in any mode. A pacemaker that provides atrioventricular synchrony at low heart rates with ventricular rate responsiveness at high heart rates may be an alternative mode for some patients.

Adult↗
PubMed1988

Evaluation of valvular regurgitation by factor analysis of first-pass angiography.

We have evaluated left ventricular regurgitation by means of factor analysis of 99mTc first-pass radionuclide angiography (FPRNA) and time-activity curve deconvolution. The FPRNA regurgitant fraction (RF) was computed in 26 individuals: 13 patients (eight mitral, three aortic, and two mitral-aortic) and 13 controls. The reference method was contrast ventriculography (CV) performed within 1 hr after FPRNA. In 19 patients, CV was preceded by the determination of cardiac output, using indocyanine green dye (n = 16) or thermodilution technique (n = 3), to determine a catheterization regurgitant fraction (CATH-RF). Lung and left ventricular (LV) time-activity curves were gathered by factor analysis and the FPRNA regurgitant fraction assessed by a lagged normal deconvolution of these curves. In valvular regurgitation, the LV deconvolved curve demonstrates the appearance of a long transit time component that is amenable to quantification. The presence of regurgitation was determined by contrast ventriculography. With a 10% RF as an acceptable upper limit of normal for nonregurgitant patients, FPRNA yielded one false-negative and no false-positive studies (n = 26), while CATH-RF yielded two false-negative and four false-positive determinations (n = 19). The following are results of quantitative determination of RF (mean +/- s.d.): FPRNA 0.39 +/- 0.19 (n = 13 Valvular), 0.01 +/- 0.03 (n = 13 Controls); CATH 0.34 +/- 0.24 (n = 11 Valvular), 0.13 +/- 0.12 (n = eight controls). FPRNA was able to differentiate (p less than 0.001) between control patients (CV grading 0) and mild/moderate regurgitation (CV grading 1+ or 2+) and severe regurgitation (3+ or 4+) (p less than 0.025).

Adult↗
PubMed1988

Light chain cardiomyopathy associated with small-vessel disease.

Intramyocardial small-vessel disease associated with systemic light chain deposition is a rare condition that may occur in patients with monoclonal plasma cell proliferation. This article describes a 39-year-old woman who had experienced several episodes of subendocardial myocardial infarction and was found to have plasma cell dyscrasia. Endomyocardial biopsy revealed kappa light chain deposits along the sarcolemmal and vascular basement membranes, the latter of which resulted in vascular occlusion and myocardial infarction. Postmortem examination showed polyvisceral deposition of kappa light chains. This rare complication of plasma cell proliferative process has a poor prognosis.

Adult↗
PubMed1987

Left ventricular derived cardiac output.

Measurement of cardiac output (CO) requires right-sided cardiac catheterization. However, to save time and reduce costs, only left-sided cardiac catheterization is usually performed in most patients with suspected coronary artery disease. Thus, CO is not measured. To determine if CO can be measured from the left side of the heart, 24 patients undergoing cardiac catheterization had near-simultaneous determination of CO after indocyanine green dye was injected into the pulmonary artery and left ventricular (LV) cavity. There was close agreement between pulmonary artery and LV derived cardiac outputs (Pulmonary artery = 0.93 LV + 0.12). The pulmonary artery derived CO was 5.7 +/- 2.0 liters/min and the LV derived CO was 6.1 +/- 2.2 liter/min. Also, there was a close relation between pulmonary artery derived stroke volume (82 +/- 33 ml) and LV derived stroke volume (86 +/- 36 ml). Thus, CO can be accurately measured after injection of indocyanine green dye into the LV cavity.

Adult↗
PubMed1986

Optimum AV interval in dual chamber pacemakers.

Approximately 50-70% of permanent implanted pacemakers are dual chamber pacemakers. However, little is known concerning adjustment of the atrioventricular (AV) interval to maximize cardiac output. Ten consecutive patients with complete heart block and dual chamber pacemakers were paced at heart rates of 80, 100, and 118 beats/minute and at five AV intervals with simultaneous measurements of cardiac output using pulsed Doppler. Maximum cardiac output occurred at AV intervals of 150 and 200 ms at rates of 80 and 100 beats/minute, and at 150 ms at a rate of 118 beats/minute (p less than .05). An increase in the AV interval to 250 ms resulted in a decrease in cardiac output at all heart rates (p less than .01). We recommend the noninvasive measurement of cardiac output, if available, for determining the optimum AV interval in an individual patient; otherwise, an AV interval of 150 or 200 ms will provide the highest cardiac output in most patients.

Cardiac Output↗
PubMed1986

Yield of endomyocardial biopsy in patients with biventricular failure. Comparison of patients with normal vs reduced left ventricular ejection fraction.

Twenty five patients with biventricular failure underwent endomyocardial biopsy procedures. Twelve of these 25 patients had normal left ventricular ejection fraction. Endomyocardial biopsy sampling was useful in eight of 12 patients (67 percent) with biventricular failure and normal left ventricular ejection fraction. Biopsy specimens in five of these 12 patients demonstrated endocardial or infiltrative heart disease and excluded these diseases in three other patients with constrictive pericarditis. This study suggests that the clinical presentation of biventricular failure, combined with the noninvasive determination of a normal left ventricular ejection fraction, is helpful in selecting patients for endomyocardial biopsy study. Patients with biventricular failure and normal left ventricular ejection fractions have a high probability of having pericardial or infiltrative heart disease, conditions that often can be differentiated only by analysis of myocardial tissue. Hemodynamic assessment of patients without infiltrative processes further allows one to eliminate those patients with a high likelihood of having constrictive pericardial disease.

Adolescent↗
PubMed1986

The postextrasystolic murmur response to gradient in hypertrophic cardiomyopathy.

Fourteen patients with hypertrophic cardiomyopathy, 40 with aortic stenosis, and 4 with discrete subaortic stenosis had phonocardiograms during left heart catheterization that showed changes in the magnitude of the murmur in response to increases in the postextrasystolic gradient. All patients showed increases in the gradient of the left ventricular outflow tract during the postextrasystolic beat. Of the 44 patients with aortic stenosis and discrete subaortic stenosis, 42 (95%) had increases in murmur magnitude, in contrast to 9 (64%) of 14 patients with hypertrophic cardiomyopathy. Only 2 of 7 patients with hypertrophic cardiomyopathy and resting gradients of more than 25 mm Hg had murmur increases. Our study shows that the systolic murmur in hypertrophic cardiomyopathy, unlike the outflow tract murmur in aortic stenosis or discrete subaortic stenosis, does not track consistently with the magnitude of the outflow tract gradient.

Adult↗
PubMed1985

Stress ventricular function test in conscious, nonthoracotomised dogs to assess cardiac drug efficacy.

The measurement of left ventricular (LV) function is frequently performed in unconscious or thoracotomised animals in the resting state; these conditions may seriously affect the basal haemodynamic state. To assess myocardial function in conscious animals, a technique was developed to place a catheter across the atrial septum into the left ventricle without a thoracotomy. A stress ventricular function test (SVFT) was performed by raising the systemic blood pressure with methoxamine in the conscious dog. In order to demonstrate the effectiveness of the SVFT in the detection of a decrease in ventricular function, a SVFT was performed before and after the acute infusion of verapamil to determine resting and reserve LV function. A slope relating systolic aortic pressure to the LV end-diastolic pressure was obtained in 10 dogs using a low dose (0.005) and in four dogs a high dose (0.01 microgram X kg-1 X min-1) verapamil (V). The mean slope before V was 3.6 +/- 1.2 and after 2.0 +/- 0.92 (p less than 0.001). The day-to-day variability of the SVFT was less than 22% (coefficient of variability). The SVFT is a sensitive, reproducible method to assess resting and increased or decreased myocardial contractility and is useful in selecting appropriate doses of cardiac drugs to determine their effect on the myocardium during acute and chronic infusion studies in the conscious, nonthoracotomised dog.

Animals↗