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Biomedical subjects

W L Henry

Publications and source records attributed to W L Henry.

At least 55 records · Page 3Linked to original sources
PubMed1988

Failure of ambulatory electrocardiographic monitoring to predict results of programmed electrical stimulation. Studies in patients with clinical ventricular tachyarrhythmias.

To test for an association between the results of ambulatory electrocardiographic monitoring (AEM) and programmed electrical stimulation (PES), or whether other factors better predict the results of PES, 57 patients (36 male and 21 female patients) presenting with either ventricular fibrillation (49 percent; 28/57) or sustained ventricular tachycardia (51 percent; 29/57) were studied. Each patient underwent AEM and PES using up to three ventricular extrastimuli. Sixty-three percent (36/57) had coronary disease; and of these, ventricular tachycardia was present during AEM in 64 percent (23/36) and induced by PES in 78 percent (28/36). With the addition of patients with other cardiac diagnoses, the results were 58 percent (33/57) and 60 percent (34/57), respectively. No AEM variable was positively associated with inducible ventricular tachycardia, including frequency of ventricular premature depolarizations, multiformity, couplets, or ventricular tachycardia. Clinical variables positively associated with inducible ventricular tachycardia were coronary disease, previous myocardial infarction, left ventricular dysfunction, male sex, and a history of recurrent arrhythmia. Therefore, clinical characteristics are more useful for predicting the results of PES than information derived from AEM.

Cardiac Pacing, Artificial↗
PubMed1988

Effect of acute changes in heart rate on Doppler pulmonary artery acceleration time in a porcine model.

Doppler measurements of pulmonary artery (PA) acceleration time (AT) have been used clinically to estimate PA pressure. However, these studies have been performed primarily in patients without tachycardia. To determine the effect of acute changes in heart rate on PA AT, atrial pacing studies were performed in seven closed-chest pigs. Pulsed Doppler PA flow velocity recordings were obtained from a parasternal position at pacing rates from 100 to 140 beats/min. PA pressure remained constant (mean +/- SD = 14 +/- 5 mm Hg) over the entire range of paced rates. When PA Doppler measurements were compared at heart rates of 100 and 140 beats/min, there were decreases at the higher heart rate in both acceleration time (110 +/- 12 vs 83 +/- 11 ms, p less than 0.01) and ejection time (ET) (315 +/- 23 vs 237 +/- 21 ms, p less than 0.01). In contrast, there was no change in either PA peak flow velocity (69 +/- 15 vs 62 +/- 18 cm/s) or the ratio of AT/ET (0.35 +/- .02 vs. .36 +/- .03). Consequently, when estimating PA pressure in states of tachycardia, the PA AT/ET ratio may be a more useful measurement than PA acceleration time.

Animals↗
PubMed1988

Vasoreactivity in isolated perfused atherosclerotic human coronary arteries.

Atherosclerosis may be important in the modulation of arterial vasoreactivity and coronary artery flow. Since the endothelium is reduced or absent in atherosclerosis, drug effects are enhanced or modulated. To examine this hypothesis, vasoreactivity induced by serotonin (5-HT) was studied in isolated, perfused, and pharmacologically responsive normal and atherosclerotic human coronary arteries obtained within five hours post mortem. In this model, flow was maintained through the vessels and the effects of vasospasm and vasorelaxation on decreasing and increasing flow respectively were measured. Vessels 3 cm long and approximately 1.5 mm in internal diameter were dissected free and perfused at constant pressure (30 mm Hg) with oxygenated Krebs bicarbonate solution. 5-HT was introduced in the perfusate at 10(-5) M final concentration as a pulse of 100 ml followed by a 1-l washout with drug-free solution. Flow rate and total flow were measured. Normal and atherosclerotic coronary arteries showed peak reductions in flow rate of 22% and 92% respectively, while the times to peak reduction of flow averaged 6 and 4 min and the times to 50% relaxation averaged 13 and 24 min. Ultrasound imaging showed that heavily atherosclerotic regions with extensive focal plaque maintained the induced spasm for a longer period than regions with less disease within the same vessel. Silver nitrate staining showed that these heavily atherosclerotic regions were devoid of endothelium. Thus, atherosclerotic human coronary arteries show a larger magnitude of spasm which persists for a longer period of time as compared to normal coronaries.(ABSTRACT TRUNCATED AT 250 WORDS)

Coronary Artery Disease↗
PubMed1988

[Acute changes in hematocrit: their effect on flows in the great arteries of newborns].

To study the effect of acute hematocrit changes on the central circulation of human neonates, pulsed Doppler echocardiography was performed to evaluate flow velocities in the main pulmonary artery (PA) and the ascending aorta (Ao) five and seven hours of age in 16 polycythemic neonates (mean hematocrit of 68.1%), and in 12 normal neonates (mean hematocrit of 57.1%). All the polycythemic neonates were asymptomatic and underwent isovolumic partial exchange transfusion between five and seven hours of age to lower their mean hematocrit to 51.3%. Flow velocity integral per min (FVI/min) (cm/min), acceleration time (AT) (ms), and the ratio of pre-ejection period to ejection time (PEP/ET) were measured on the PA and Ao flow velocity tracings. Despite the significant differences in hematocrit, no significant difference was observed in any of their flow velocity indices at five hours age between the normal and polycythemic neonates. All flow velocity indices remained unchanged between five and seven hours of age in normal neonates. In polycythemic neonates, PA FVI/min and Ao FVI/min increased significantly between five and seven hours of age, reflecting increases in flow in both great arteries, while the difference between Ao FVI/min and PA FVI/min decreased, suggesting a reduction in a left-to-right shunt via the ductus arteriosus. Moreover, PA-AT increased and PA-PEP/ET decreased significantly, suggesting a decrease in pulmonary vascular resistance. These changes caused by an acute decrease in hematocrit resembled the changes in the central circulation previously reported to occur in normal neonates during the postnatal period. In conclusion, an acute decrease in hematocrit transiently accelerates physiological changes in the central circulation during the neonatal period.

Aorta↗
PubMed1987

Refining the criteria for pulsed Doppler diagnosis of mitral regurgitation by comparison with left ventricular angiography.

Doppler echocardiography is established as a useful method for detecting mitral regurgitation (MR). However, studies also show that Doppler echocardiography may be too sensitive for diagnosing pathologic MR. To determine whether the false-positive or clinically insignificant diagnosis of MR can be eliminated by defining more specific diagnostic criteria, pulsed Doppler findings were compared with left ventricular angiographic findings in 81 patients. Using the conventional Doppler criterion of any systolic increased spectral dispersion detected in the left atrium, sensitivity was 100% and specificity was 76%. Using holosystolic increased spectral dispersion as the criterion, sensitivity was 100% and specificity was 92%. Using the combined criteria of holosystolic increased spectral dispersion plus peak regurgitant blood flow velocity of greater than 150 cm/s, sensitivity was 100% and specificity was 97%. Doppler studies in 20 clinically normal persons showed that the combined Doppler criteria were 100% specific. In conclusion, the presence of holosystolic increased spectral dispersion within the left atrium with a peak regurgitant flow velocity greater than 150 cm/s appears to be as sensitive as and more specific than the presence of any systolic Doppler increased spectral dispersion in identifying patients with MR.

Angiography↗
PubMed1987

Amiodarone for maintenance of sinus rhythm after conversion of atrial fibrillation in the setting of a dilated left atrium.

Previous reports suggest that the finding of left atrial (LA) dilatation (greater than 45 mm) by echocardiography identifies patients not likely to maintain sinus rhythm after conversion of atrial fibrillation (AF). However, these studies antedate the availability of amiodarone, an antiarrhythmic agent that reportedly is effective in patients with AF in whom other drug therapy has failed. To analyze the relation between LA size and the ability to maintain sinus rhythm with amiodarone therapy, 28 patients, aged 32 to 87 years (mean 61), with an LA dimension greater than 45 mm (range 46 to 78, mean 57) were studied. Thirteen patients (46%) had valvular heart disease, 10 (36%) dilated cardiomyopathy and 5 (18%) miscellaneous disorders. In 25 patients (89%) quinidine therapy had failed. After therapy with amiodarone, sinus rhythm returned in all patients and was maintained. Therapy was judged completely successful in 10 patients (alive and still in sinus rhythm with at least 1 year of follow-up), partially successful in 11 (maintaining sinus rhythm for at least 6 months before a change in status) and failed in 7. Completely successful therapy was accomplished in 9 of 18 patients with an LA dimension between 46 and 60 mm, but in only 1 of 10 patients with an LA dimension greater than 60 mm (p less than 0.05). Thus, patients with LA dimensions between 46 and 60 mm who are significantly compromised by AF can often be maintained in sinus rhythm with amiodarone therapy. However, in patients with larger LA dimensions. AF is likely to return despite aggressive antiarrhythmic therapy with amiodarone, a drug with potentially serious side effects.

Adult↗
PubMed1987

Evaluation of pulmonary artery pressure and resistance by pulsed Doppler echocardiography.

Pulsed Doppler echocardiography was used to examine the relation between pulmonary valve motion and pulmonary artery (PA) flow velocity patterns in 39 adults. In 16 patients with normal PA pressure (mean pressure less than 20 mm Hg), PA flow velocity accelerated slowly to a peak flow velocity at midsystole (time to peak flow velocity, or acceleration time = 134 +/- 20 ms [mean +/- standard deviation]), followed by a slow deceleration to the end of ejection, producing a "dome-like" appearance. In contrast, in 23 patients with elevated PA pressure (mean pressure 20 mm Hg or more), flow velocity accelerated rapidly to a peak flow velocity in early systole (acceleration time = 88 +/- 25 ms, p less than 0.01), followed by rapid flow velocity deceleration to a nadir in midsystole. In 13 of these patients, a transient increase in flow velocity occurred in late systole, producing a "spike and dome" appearance. In patients with an acceleration time of 120 ms or less, there was a negative linear correlation with mean PA pressure, expressed by the equation: mean PA pressure = 90 - (0.62 X acceleration time). The standard error of the estimate was 8.3 mm Hg. A similar negative linear correlation was found between PA acceleration time and total pulmonary resistance. Using a PA acceleration time of 100 ms or less resulted in a 78% sensitivity and a 100% specificity for detection of elevated PA pressure. Although this Doppler method cannot precisely estimate PA pressure, it can be helpful in separating patients with normal pressure from those with elevated PA pressure.

Adult↗
PubMed1987

Videodensitometric determination of minimum coronary artery luminal diameter before and after angioplasty.

Quantitative measurements of coronary stenoses were made from digital coronary angiograms in 19 patients before and after percutaneous transluminal coronary angioplasty (PTCA). Two methods of measurement were compared. Mean stenosis before PTCA was 67 +/- 10% by the edge detection method and 67 +/- 12% by videodensitometry (difference not significant). After PTCA, the mean stenosis was 32 +/- 14% by edge detection and 30 +/- 13% by videodensitometry (difference not significant). In addition, a new method was developed to rapidly calculate the absolute minimum luminal area and diameter by videodensitometry. The minimum luminal diameter before PTCA was 1.0 +/- 0.5 mm and after PTCA increased to 2.4 +/- 0.5 mm (p less than 0.001). The validity of the videodensitometric method was analyzed in a series of Lucite phantom studies, which suggested that when there is an irregular angiographic appearance, the densitometric method may be more accurate than standard edge detection methods. Digital acquisition of coronary angiograms provides a means for rapid application of quantitative analysis during coronary interventional procedures.

Angioplasty, Balloon↗
PubMed1987

Effect of left ventricular size on early diastolic left ventricular filling in neonates and in adults.

Peak early diastolic left ventricular (LV) filling rate has been used as an index of LV diastolic function. However, it is known to be affected by LV size. Peak early diastolic transmitral flow velocity measured by pulsed Doppler echocardiography has also been proposed as a noninvasive method of assessing LV diastolic function. To determine if peak early diastolic mitral flow velocity also is influenced by LV size, 20 normal neonates (age 2 days) and 21 normal adults (mean age 38 years) were studied using pulsed Doppler echocardiography to measure mitral flow velocity and M-mode echocardiography to estimate LV end-diastolic volume and mitral valvular area. Peak early diastolic LV filling rate was calculated by multiplying peak early diastolic mitral flow velocity by mitral valvular area. Adults had significantly larger LV end-diastolic volumes (mean +/- standard deviation 108 +/- 25 vs 7 +/- 3 ml) and higher peak early diastolic LV filling rates (305 +/- 75 vs 29 +/- 10 ml/s) than neonates (both p less than 0.001). However, no significant difference was found in peak early diastolic mitral flow velocity between adults and neonates (61 +/- 10 vs 58 +/- 11 cm/s). These data suggest that peak early diastolic mitral flow velocity is independent of LV size. Since peak LV filling rate is equal to the product of peak mitral flow velocity and mitral valvular area, the correlation between peak early diastolic LV filling rate and LV size is probably due to differences in mitral valvular area rather than differences in peak mitral flow velocity.

Adult↗
PubMed1987

Relationship between age, body size, gender, and blood pressure and Doppler flow measurements in the aorta and pulmonary artery.

Previous studies have demonstrated a relationship between both age and body surface area (BSA) and M-mode echocardiographic measurements of left ventricular, left atrial, and aortic root dimensions and left ventricular wall thickness. We evaluated the relationships between age, BSA, gender and blood pressure, and Doppler aortic and pulmonary artery (PA) flow velocity measurements in 97 adults, aged 21 to 78 years, without clinical evidence of cardiac disease. No significant relationship was found between gender or blood pressure and aortic or PA flow velocity measurements. Aortic peak flow velocity, flow velocity integral, and average acceleration decreased with increasing age (all p less than 0.001), whereas ejection time (corrected for heart rate) increased, and acceleration time did not change. In contrast, there was no relationship between age and Doppler PA flow velocity measurements. Although there was no relationship between BSA and Doppler aortic flow measurements, PA peak flow velocity and average acceleration increased, while acceleration time decreased with increasing BSA (all p less than 0.02). Decreases in aortic peak flow velocity and flow velocity integral may be partly related to known increases in aortic root diameter with aging. The relationship between PA flow velocity measurements and BSA is not readily explained.

Adult↗
PubMed1987

A pulsed Doppler echocardiographic study of the postnatal changes in pulmonary artery and ascending aortic flow in normal term newborn infants.

Postnatal circulatory adaptations were studied with Doppler echocardiographic measures of flow velocity in the main pulmonary artery (PA) and ascending aorta (Ao) in 45 normal full-term neonates at 5 hours and at 27 hours after birth. PA flow velocity integral (FVI) was measured as the area under the systolic flow velocity curve and reflected total systemic flow in the presence of a left-to-right shunt through the ductus arteriosus. This index increased from 5 and 27 hours age, while Ao FVI, reflecting total pulmonary flow, remained unchanged. Evidence of a left-to-right ductal shunt demonstrated as diastolic retrograde flow in the main PA was detected in 42 neonates at 5 hours and in only four subjects after 27 hours of age, indicating a patent ductus arteriosus at 5 hours of age and its subsequent closure. In the PA, acceleration time (AT) increased while pre-ejection period to ejection time ratio (PEP/ET) decreased from 5 to 27 hours of age, reflecting the physiologic fall in PA pressure. In the Ao, FVI, AT, and PEP/ET remained unchanged, suggesting little change in left ventricular function.

Aorta↗
PubMed1987

Effect of age, sex, and body surface area on echocardiographic left ventricular wall mass in normal subjects.

M-mode echocardiography was used to estimate left ventricular wall mass in 136 older normal subjects (Group I: 78 men and 58 women, ages 20 to 97 years) and 105 younger normal subjects (Group II: 52 male and 53 female subjects, ages 1 day to 23 years). Echocardiographic left ventricular mass (in grams) was estimated from the following formula: left ventricular mass = 1.05 ([ left ventricular internal diastolic dimension + ventricular septal thickness (diastole) + posterior wall thickness (diastole)] - [left ventricular internal diastolic dimension]). In both groups, female subjects had a slightly smaller left ventricular mass than male subjects (mean difference 7.2% in Group I, p less than 0.05, and 3.6% in Group II, p = 0.05) for any given age and body surface area. Left ventricular mass varied linearly with body surface area and increased as a function of age. In group I subjects, echocardiographic left ventricular mass (in grams) could be estimated by the general formula: left ventricular mass = 124 (body surface area) + A +/- C, where A is the age-dependent intercept; +/- C encompasses a 95% prediction interval for normal values, which is assumed to be nearly constant (+/- 58 g); and body surface area is expressed in square meters. In the Group II (younger) subjects, with age not considered, left ventricular mass (in grams) could be estimated from the following formula: left ventricular mass = 115 (body surface area) -11 +/- C, where +/- C = +/- 32% and this 95% prediction interval varies as a percentage of the mean.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Doppler echocardiographic assessment of left ventricular systolic and diastolic function in mild hypertension.

Abnormalities in left ventricular (LV) wall thickness and mass have been demonstrated in patients with mild hypertension utilizing M-mode echocardiography. In addition, studies using radionuclide angiography have demonstrated abnormalities in early diastolic LV filling in asymptomatic hypertensive patients with normal ejection fraction and cardiac output. Recently, Doppler recordings of flow velocity in the ascending aorta and through the mitral valve have been shown to provide useful information about LV function. To determine whether flow abnormalities could be detected in patients with mild hypertension, we recorded Doppler aortic and mitral valve flow velocities in 21 men with mild hypertension. Casual systolic blood pressure was 147 +/- 18 mm Hg (mean +/- SD) and diastolic blood pressure was 96 +/- 9 mm Hg. LV mass (310 +/- 75 g) was elevated (i.e., above the 95% normal prediction interval) in 8 of 19 patients who underwent M-mode echocardiography; LV ejection fraction was normal in all patients (mean, 80%). As in previous studies in normal subjects, we found in these hypertensive patients an inverse correlation between age and both aortic peak flow velocity (r = -0.51, p less than 0.05) and transmitral early diastolic peak flow velocity (r = -0.44, p less than 0.05) and a positive relationship between age and mitral valve late diastolic peak flow velocity (r = 0.73, p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

[Pulsed Doppler echocardiographic detection of regurgitant blood flow in the ascending, descending and abdominal aorta of patients with aortic regurgitation].

To ascertain whether the presence of retrograde holo-diastolic flow (RHF) in the ascending, descending or abdominal aorta is indicative of the severity of aortic regurgitation (AR), ascending, descending and abdominal aortic flow velocities were measured by pulsed Doppler echocardiography in 35 patients with AR and in 18 patients without AR, confirmed by aortography. Among the 35 patients with AR, 15 had mitral regurgitation, 11 had mitral stenosis, eight had aortic stenosis, five had prosthetic mitral valves, four had prosthetic aortic valves and two had aorto-pulmonary shunts. Satisfactory flow velocity recordings were obtained from the ascending aorta of 47 patients (89%), from the descending aorta of 39 patients (74%) and from the abdominal aorta of 43 patients (81%). In the ascending aorta, 30 of 32 AR patients with satisfactory recordings had RHF, while only one of the 15 patients without AR had RHF. None of the patients without AR had RHF, in either the descending or abdominal aorta. In the descending aorta, all 11 patients with 3+ or 4+ AR independently determined by aortography had RHF, while only three of 16 patients with 1+ or 2+ AR had RHF. Two of the three patients had aorto-pulmonary shunts. In the abdominal aorta, all 11 patients with 3+ or 4+ AR had RHF, while only one of the 22 patients with 1+ or 2+ AR had RHF. The latter patient had an aorto-pulmonary shunt. Identification of RHF in the descending or abdominal aorta is a useful means of distinguishing patients with severe AR from those with minimal or no AR.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1987

The complications of diabetes mellitus.

The present concept of the pathogenesis of diabetic complications is discussed with particular emphasis on abnormalities in sorbitol and myoinositol metabolism and the effects of glycosylation of proteins.The modern approach to selected chronic complications of diabetes, particularly those that have serious and troubling implications, are reviewed.

Diabetes Complications↗
PubMed1986

Pulsed Doppler echocardiographic study of left ventricular filling in dilated cardiomyopathy.

Patients with dilated cardiomyopathy (DC) have been reported to have abnormal left ventricular (LV) diastolic properties. To evaluate LV diastolic filling characteristics in patients with DC, pulsed Doppler echocardiography was used to study mitral flow velocity in 21 patients with DC and mitral regurgitation (MR), 12 patients with DC but no MR and 19 age-matched normal subjects. Diagnosis of MR was based on the Doppler echocardiographic finding of holosystolic turbulent flow in the left atrium. Peak mitral flow velocity in early diastole (PFVE) and during atrial systole (PFVA), PFVA/PFVE and deceleration half-time of early diastolic flow were measured from Doppler mitral flow velocity recordings. In 21 patients with DC and MR, PFVE (61 +/- 13 cm/s), PFVA (37 +/- 19 cm/s) and PFVA/PFVE (0.6 +/- 0.4) were not significantly different from PFVE (53 +/- 10 cm/s), PFVA (47 +/- 12 cm/s) and PFVA/PFVE (1.0 +/- 0.4) in normal subjects (p greater than 0.05). Deceleration half-time in DC patients with MR (62 +/- 32 ms) was shorter than normal (87 +/- 25 ms) (p less than 0.05). In contrast, PFVE (31 +/- 11 cm/s) was lower and PFVA/PFVE (1.7 +/- 0.8) was higher in the 12 DC patients without MR than in normal subjects and DC patients with MR (p less than 0.005). PFVA (46 +/- 8 cm/s) and deceleration half-time (88 +/- 33 ms) in patients without MR were not significantly different from normal mean values. Thus, abnormalities of peak diastolic mitral flow velocity were detected in DC patients without MR but not in DC patients with MR, suggesting that MR masks LV filling abnormalities in patients with DC.

Adult↗