Biomedical subjects

D L Clement

Publications and source records attributed to D L Clement.

At least 73 records · Page 4Linked to original sources

PubMed1993

Delayed restoration of atrial function after conversion of atrial flutter by pacing or electrical cardioversion.

It is often suggested but never proven that atrial function is not affected during atrial flutter, nor after its conversion to normal sinus rhythm. To evaluate this hypothesis, a prospective study was performed in 22 patients (age range 20 to 88 years) with atrial flutter. Diastolic transmitral flow was analyzed with echo-Doppler before and after conversion. After randomization, conversion was attempted with overdrive pacing or up to two 50 J shocks. If the initial method was unsuccessful, a 200 J shock was administered. All patients were converted to sinus rhythm with this protocol. Shortly after conversion (at 1 and 6 hours), atrial contribution to ventricular filling was absent in 4 of 22 patients. In the remaining 18 patients, atrial contribution to ventricular filling was small. Atrial contribution to transmitral flow improved from 20 to 27% within 24 hours (p < 0.01) and increased further to 38% at 6 weeks (p < 0.005). Peak velocity of late diastolic filling increased from 0.28 m/s after 1 hour to 0.39 m/s after 24 hours (p < 0.0001) and improved even further during later follow-up. In 1 patient, an effective atrial systole was not observed until the 14th day. Cardiac output did not change significantly during the study period. No differences were observed between the conversion modalities. In conclusion, atrial dysfunction is present immediately after conversion of atrial flutter to normal sinus rhythm. This dysfunction occurs also after overdrive pacing and can last > 1 week. The findings suggest that stasis in the atria can remain temporarily present after successful conversion of atrial flutter to sinus rhythm.

Adult↗

PubMed1993

Coagulation system activation and increase of D-dimer levels in peripheral arterial occlusive disease.

The aim of the present study was to document coagulation system activation and basal fibrinolysis in peripheral arterial occlusive disease (PAOD) at stage II of Fontaine's classification. In 34 patients, prothrombin fragment (F1 + 2), thrombin-antithrombin III complexes (TAT), and D-dimer concentrations were evaluated before and after a standard treadmill test. Basal levels in PAOD of F1 + 2 (1.25 +/- 0.19 nmol/liter) and of TAT (3.34 +/- 0.35 micrograms/liter) were significantly increased compared to those obtained in age- and sex-matched healthy controls (0.68 +/- 0.06 nmol/liter and 2.30 +/- 0.33 micrograms/liter, respectively), showing baseline activation of the clotting cascade. A secondary activation of the fibrinolytic system was evidenced by the highly significant increase of basal D-dimers (719 +/- 99 ng/dl in PAOD vs. 229 +/- 37 ng/dl in controls). Treadmill exercise failed to increase the study parameters significantly further. Walking distance (583 +/- 40 m) was correlated with the preexercise ankle to brachial systolic blood pressure ratio (r = 0.485, P < 0.005) and inversely with the level of D-dimers (r = -0.425, P < 0.02). Under baseline conditions, the latter parameter was correlated as well with the antigen concentration of urokinase-type plasminogen activator (u-PA; r = 0.503, P < 0.002). These results indicate that stage II PAOD is characterized by an activation of the clotting cascade in baseline conditions evidenced by increased F1 + 2 and TAT. A secondary activation of the fibrinolytic system with increased u-PA antigen levels accounts for the elevated D-dimers. Treadmill exercise was unable to increase these parameters further.

Aged↗

PubMed1993

24 hour ambulatory blood pressure variability and cardiac parasympathetic function 2 and 6 weeks after acute myocardial infarction.

The aim of the study was to assess non-invasively circadian blood pressure rhythm as well as the influence of parasympathetic function 2 and 6 weeks after acute myocardial infarction treated with beta-blocking agents. Twenty-four patients with uncomplicated first myocardial infarction, and aged less than 60 years, underwent ambulatory blood pressure recordings every 15 min during the day (0900-2100 h) and every 30 min during the night (2100-0900 h), 2 and 6 weeks after infarction. The deep breathing test (6 breaths/min) was performed on each occasion. Normal circadian blood pressure rhythm was maintained with a nocturnal decline of 10 to 15%. Both for systolic and diastolic blood pressure a moderate increase was obtained after 6 weeks (107.8 +/- 9.2 mmHg vs. 111.8 +/- 10.3 mmHg; NS and 64.9 +/- 4.5 mmHg vs. 68.8 +/- 6.5 mmHg; p < 0.05). The respective blood pressure variations were significantly higher at that time (10.0 +/- 2.4 mmHg vs. 13.6 +/- 4.2 mmHg; p < 0.001 and 7.9 +/- 1.7 mmHg vs. 11.7 +/- 3.5 mmHg, p < 0.001). There was a close correlation (r = 0.60, p < 0.005) between 24-h diastolic blood pressure variability and the results of the parasympathetic function test (deep breathing) 2 weeks after infarction. We conclude that the circadian blood pressure rhythm persists after acute myocardial infarction. The correlation between blood pressure variability and parasympathetic function early after infarction suggests a role for vagal control in post-infarction blood pressure variability.

Acute Disease↗

PubMed1993

Peripheral vascular changes and ambulatory blood pressure profiles.

This study aimed to correlate blood pressure (BP) level assessed either by casual or by 24-h ambulatory BP monitoring and regional (calf and finger) blood flow and associated vascular resistance in subjects with low, intermediate, and high BP. In 75 subjects covering the range from low BP to normo- and hypertension, blood flow at calf and finger vessels were simultaneously measured using an ECG-triggered venous occlusion plethysmograph. Correlations were calculated between regional blood flow or vascular resistance and BP defined from casual and from 24-h ambulatory BP registrations, at rest, and after 3 min of arterial occlusion (reactive hyperemia). Correlations over the whole BP range, between calf and finger vascular resistances and BP, were highly significant both for casual (0.650 < r < 0.776) and for ambulatory (0.531 < r < 0.781) BP. The relations remained significant after adjustment for the age dependency of the blood pressure. At any BP level skin (finger) blood flow at rest and after arterial occlusion was higher than muscle (calf) blood flow. These data indicate that there is a progressive decrease in vasodilating capacity from low to high BP in both muscle and skin vessels. However, in the zone of borderline to moderate essential hypertensives, blood flow after 3 min arterial occlusion was already significantly decreased in the muscle circulation when compared to normotensives, while still maintained in the skin circulation.

Adult↗

PubMed1993

Left ventricular function and regression of left ventricular hypertrophy in essential hypertension.

Although left ventricular hypertrophy (LVH) is an adaptive response to the increased load imposed on the heart in patients with hypertension, it ultimately is itself a major risk factor for cardiovascular disease. The influence of LVH on left ventricular function and on the coronary circulation, and the occurrence of serious ventricular arrhythmias are the major mechanisms of this increased risk. There is no doubt that regression of LVH occurs, but there are clear differences in this respect among antihypertensive drugs: angiotensin-converting enzyme (ACE) inhibitors and calcium antagonists produce the best response. Whether regression of LVH also causes an improvement in left ventricular function is unclear; various studies using the same drugs have yielded contradictory results. Furthermore, it has yet to be determined whether regression of LVH has a positive influence on the long-term prognosis in such patients; the results of the European Multicenter Study OvA will help in shedding more light on this important question.

Antihypertensive Agents↗

PubMed1993

Autonomic imbalance in the recovery period after myocardial infarction.

The aim of the study was to evaluate the responses to autonomic function tests during the healing period of myocardial infarction (AMI). In 24 patients, at 2 and 6 weeks after the acute event, Valsalva manoeuvre, deep breathing at 6 breaths per min, isometric handgrip and cold pressor tests were performed. Responses of arterial blood pressure (BP) and heart rate (HR) were measured. At 2 weeks post AMI a significant decrease in parasympathetic tone was noted: HR reduction during deep breathing: 18.5 +/- 5.7 beats.min-1 for controls vs 9.7 +/- 2.6 beats.min-1 for AMI, P < 0.001. Systolic BP response to handgrip and cold pressor test was only slightly (non significantly) increased: 30.6 +/- 12.9 mmHg (controls) vs 40.0 +/- 20.5 mmHg (AMI) for the handgrip test and 13.8 +/- 8.1 mmHg vs 18.0 +/- 10.1 mmHg respectively for the cold pressor test. At 6 weeks post AMI, the response to the deep breathing test (15.9 +/- 5.6 beats.min-1) no longer significantly differed from that in controls. In contrast, the sympathetic stressor tests showed a significant increase in systolic BP response: 63.8 +/- 21.9 mmHg, P < 0.001 and 26.1 +/- 14.9 mmHg, P < 0.05, respectively for the handgrip and cold pressor tests. It appeared that infarct localization had no effect on autonomic function tests. There is evidence of autonomic imbalance both at 2 and 6 weeks after AMI, with a rapid but transient decrease in vagal activity and enhancement of orthosympathetic nervous tone; this was markedly more pronounced at 6 weeks post AMI despite treatment with beta-blocking agents in all patients.

Adult↗

PubMed1993

Haptoglobin polymorphism and complications in established essential arterial hypertension.

OBJECTIVE: Salt sensitivity and the magnitude of systolic blood pressure have been linked to haptoglobin (Hp) polymorphism in normotensives. The aim of the present study was to investigate the indices of hypertension, the severity of complications and the occurrence of coronary and peripheral artery disease for the various haptoglobin phenotypes and their relation to the therapeutic needs (number and class of drugs) of established arterial hypertensives. DESIGN: Haptoglobin polymorphism was studied in 302 Caucasians with established essential arterial hypertension who had been treated for at least 1 year. METHODS: Haptoglobin polymorphism was studied using starch-gel electrophoresis of haemoglobin-supplemented serum. RESULTS: The relative allele frequencies of Hp 1 and Hp 2 (0.036 and 0.640, respectively) in established hypertensives were comparable with those of the control population. Logistic regression analysis confirmed that Hp 2-2 contributes to the therapeutic needs in hypertension. The most important factors determining therapeutic needs were coronary artery disease, Hp 2-2 phenotype, body mass index (BMI) and left ventricular hypertrophy. Although no contributive effect of serum haptoglobin concentration could be derived from the logistic regression approach, analysis of serum haptoglobin concentration demonstrated a concentration-related effect on therapeutic needs for the Hp 2-2 phenotype only. CONCLUSIONS: The present study suggests that hypertensives with an Hp 2-2 phenotype need more complex combinations of antihypertensive drugs to reduce blood pressure to the same level. The hypertensive patient carrying Hp 2-2 is more likely to accumulate atherosclerotic lesions of the coronary or peripheral arteries, despite comparable lipid levels, smoking habits and BMI. Hp 1-1 patients are characterized by a younger age at diagnosis and a lower complication rate. In view of the greater therapeutic needs and the higher complication rate, Hp 2-2 hypertensives need more careful follow-up.

Aged↗

PubMed1993

Exercise performance and diastolic filling in essential hypertension.

OBJECTIVES: To investigate the relationship between arterial blood pressure, left ventricular mass, diastolic filling and maximal exercise capacity in patients with newly diagnosed essential hypertension. DESIGN: Asymptomatic untreated patients with office blood pressure > 140/90 mmHg were studied prospectively after exclusion of associated disease. METHODS: Twenty consecutive white patients (14 male, 6 female; age 43 +/- 12 years) with office blood pressure 164 +/- 23/103 +/- 10 mmHg, mean 24-h ambulatory blood pressure 142 +/- 25/89 +/- 15 mmHg and normal systolic cardiac function underwent an echocardiographic examination to determine left ventricular mass and diastolic filling parameters and performed a bicycle ergometer test to determine maximal voluntary exercise capacity. RESULTS: In single regression analysis exercise time and maximal oxygen uptake were related to sex and age. A multiple regression showed that only age was related to exercise capacity, however. On subgroup analysis of male patients between 30 and 50 years (n = 10), exercise time (659 +/- 134 s) was significantly inversely related to mean 24-h ambulatory diastolic blood pressure (92 +/- 11 mmHg) (r = -0.67; p = 0.03) and positively to diastolic filling expressed as ratio of peak early to peak atrial filling velocity (Emax/Amax ratio; 1.34 +/- 0.40) (r = 0.65; p = 0.04) or as ratio of velocity time integral (VTI) of early filling phase to VTI of atrial filling phase (VTIE/VTIA ratio; 1.94 +/- 0.72) (r = 0.02). Maximal oxygen consumption (22.3 +/- 4.1 ml/kg/min) was significantly inversely correlated with mean 24-h ambulatory diastolic blood pressure (r = -0.67; p = 0.03), mean 24-h ambulatory systolic blood pressure (147 +/- 25 mmHg) (r = -0.82; p < 0.01), left ventricular mass (312 +/- 143 g) (r = -0.86; p < 0.01), left ventricular mass index (135 +/- 41 g/m2) (r = -0.76, p = 0.01) and positively with diastolic filling expressed as Emax/Amax ratio (r = 0.71; p = 0.02) or as VTIE/VTIA ratio (r = 0.70; p = 0.02). CONCLUSION: This study shows the important interrelation between blood pressure, cardiac mass, diastolic filling and exercise capacity. High blood pressure entrains a larger cardiac mass but slows cardiac filling and decreases exercise capacity.

Adult↗

PubMed1993

On the relationship between regional circulation and systemic blood pressure.

OBJECTIVES: The relationship between regional circulation (blood flow or calculated resistance) and systemic blood pressure (BP) is only poorly documented in the range of intermediate to low BP. METHODS: In 75 subjects covering the BP range from low, over intermediate, to high BP, venous occlusion plethysmographic recordings were performed at the calf and finger vessels. Correlations were calculated between regional blood flow or vascular resistance and BP defined from office and from 24 h ambulatory BP registrations, at rest and during reactive hyperaemia. RESULTS: At any BP level, finger blood flow at rest and during reactive hyperemia was higher than calf blood flow, and resistance was lower. The interval of 90-100 mmHg office diastolic BP was characterized by significantly (p < 0.001) higher resting finger blood flow; the increase in resting muscle blood flow was less pronounced. At rest and during reactive hyperaemia there was a stepwise increase in calf regional vascular resistance in parallel with increasing BP. For the finger circulation, increased vascular resistance was only observed for the higher BP values. Correlations between calf and finger vascular resistances and BP were positive and highly significant over the whole BP range, both for office (0.650 < r < 0.776) and for ambulatory BP (0.531 < r < 0.781). These correlations remained significant after adjustment for the age dependency. Increases in calf and finger blood flow induced by arterial occlusion were highest for the lowest BP quintiles. CONCLUSIONS: Our data further indicated that the capacity to dilate decreased progressively with increasing BP level (from asymptomatic low to high BP) for both calf and finger circulation.

Adult↗

PubMed1993

Skin capillary erythrocyte velocity and mean 24 hour ambulatory blood pressure level.

This study aimed to examine the relation between capillary dynamics and parameters of ambulatory blood pressure (BP) recordings in a range covering very low to high BP (mean arterial BP: 70-140 mm Hg). A total number of 45 subjects underwent a 24 h ambulatory BP recording at 30 min intervals. The subjects did not receive any medication. Then the subjects were subdivided in 5 categories along their mean 24 h arterial BP values < 80, 80-90, 91-105, 106-115, > 115 mm Hg. Nailfold capillaries were examined at the level of the fourth finger using TV-microscopy. Our results demonstrate that erythrocyte velocity could be maintained relatively constant (mean velocities 700-800 microns/s) within the ambulatory mean arterial blood pressure range of 80-115 mm Hg. For very low and high blood pressures significant decreases (p < 0.01) were noted. Using office mean arterial blood pressure comparable results were obtained.

Blood Flow Velocity↗

PubMed1993

Clinical aspects during long-term follow-up after DC shock ablation of the atrioventricular junction. A Belgian experience.

Ninety-three patients, who underwent DC shock ablation were reviewed over a mean follow-up period of 54 months (range 3 to 84 months). These patients (46 male and 47 female, mean age: 58 years) had failed an average of 3 drugs, and the duration of symptoms was more than 2 years. Paroxysmal atrial fibrillation or flutter was treated in 75 patients (80.6%); the remainder had supraventricular tachycardia or reciprocating tachycardia using an accessory pathway. One shock of 200 J was effective in producing third degree AV block in 40 patients (43%), while 2 or more shocks were used in another 53 patients (57%). Chronic complete heart block (CHB) was obtained in 85 patients (91%), modification of conduction was seen in 2 patients (2.1%), and failure to achieve an improvement in 6 patients (6.4). All the patients of the last group had received more than 4 shocks (200 to 400 J). However no significant difference between the amplitude of atrial and His electrograms could be shown between the CHB patients and those in whom conduction persisted. Over a mean follow-up of 54 months, 66 patients (72%) with successful ablation during the first 48 hours after the procedure remained in CHB. In 18 patients AV conduction resumed but they were all asymptomatic: 10 patients (10.8%) without antiarrhythmic therapy and 8 patients (8.6%) with medication. In conclusion, ablation of the AV junction is effective in more than 82% of patients. Most of the time long-term success can be predicted within 48 hours. However, due to the invasive character of DC shocks, this technique has been supplanted by the less aggressive radiofrequency method.

Adult↗

PubMed1992

Comparison of lisinopril and nitrendipine on the pulsatility index in mild essential arterial hypertension.

A double-blind, randomized crossover study was performed in 21 patients with essential arterial hypertension. Nitrendipine 20 mg o.d. and lisinopril 20 mg o.d. were given in a randomized order during a period of each 8 weeks. Nitrendipine and lisinopril decreased systolic and mean arterial blood pressure to a similar level without a significant increase in heart rate. The mean diastolic blood pressure was smaller with the lisinopril treatment than with the nitrendipine treatment. The blood pressure decrease was maintained in the sitting and standing position. Furthermore, only nitrendipine decreased the pulsatility index at the tibial posterior arteries, while lisinopril did not influence it significantly. This finding means that mechanisms other than the blood-pressure lowering effect are involved in the decrease of the pulsatility index.

Adult↗

PubMed1992

Venous responses to rhythmic exercise in contralateral forearm and calf.

Ten normal healthy subjects performed a rhythmic handgrip at 30% MVC (maximal voluntary contraction) with and without arterial occlusion of the same limb. Contralateral forearm and calf venous capacitance were simultaneously measured by venous occlusion plethysmography. During rhythmic handgrip at 30% MVC contralateral venous capacitance decreased by -7.17% in the forearm and by -5.14% in the calf. With arterial occlusion the decreases in venous capacitance were even more pronounced: contralateral forearm -14.4% and calf -13.1%. In a second set of experiments (n = 5) rhythmic handgrip at 30% MVC with arrest of the forearm circulation 5 s prior to the cessation of contraction was applied to examine the influence of chemically sensitive metaboreceptors per se on the evoked limb venoconstriction. During the postexercise arterial occlusion forearm venous volume decreased further to -30.6% whereas calf venous volume increased slightly but remained below the control value. After the cessation of the arterial occlusion both forearm and calf capacitance returned to baseline values. Thus, this study provided evidence that as well as a chemically generated reflex arising from the working muscle, central command was found to be involved in the increase in venomotor tone in the nonexercising limbs during rhythmic handgrip at 30% MVC.

Adult↗

PubMed1992

Blood pressure load determines left ventricular mass in essential hypertension.

In a series of 35 newly diagnosed, previously untreated patients (mean age 46 years) with mild to moderate essential hypertension, office blood pressure measurements, 24-hour ambulatory blood pressure monitoring, and determination of left ventricular mass index by echocardiography according to the formula of Devereux were performed. We aimed at correlating left ventricular mass index with systolic and diastolic office blood pressure, mean 24-hour systolic and mean 24-hour diastolic blood pressure, systolic and diastolic load. Left ventricular mass index did not correlate with office systolic and office diastolic blood pressure. On the contrary, all correlations with ambulatory blood pressure parameters and left ventricular mass index turned out to be significant (mean 24-hour systolic blood pressure: r = 0.344, P = 0.026; systolic load: r = 0.408, P = 0.020; mean 24-hour diastolic blood pressure: r = 0.490, P = 0.004; diastolic load: r = 0.504, P = 0.003). These results clearly demonstrate that ambulatory blood pressure determinants but not the office blood pressure parameters are well correlated with left ventricular mass index in mild to moderate essential hypertension. Blood pressure load is as important as mean 24-hour blood pressure in this regard.

Adult↗

PubMed1992

Transoesophageal echo-Doppler in patients suspected of a cardiac source of peripheral emboli.

The initial results of a controlled and partly blinded study aimed at evaluating the accuracy of transoesophageal echo-Doppler in detecting cardiac sources of peripheral emboli are reported. A total of 120 consecutive patients suspected of acute embolic events were entered. After completion of all investigations, the patients were classified into three groups: patients who had definitely not suffered an embolic event (controls; n = 56); patients in whom the differentiation between local thrombosis, embolic event originating from a diseased infarct-related artery or embolic event from a cardiac source was not possible (questionable cases; n = 24) and patients in whom a cardiac source of a definite embolic event was highly suspected (cardiac emboli; n = 40). Isolated interatrial septum anomaly and mitral valve prolapse were as frequent in the control group as in the embolism group. Transoesophageal echo-Doppler had a sensitivity of 83% and a specificity of 86% in correctly assigning a patient to the cardiac embolism group or to the control group. The positive and negative predictive values were 80% and 87% respectively. It is concluded that transoesophageal echo-Doppler is highly sensitive but is also specific in demonstrating cardiac sources of peripheral emboli.

Adult↗

PubMed1992

Medical treatment of peripheral vascular disease: good or bad?

The majority of patients with intermittent claudication are treated conservatively; smoking must be stopped and exercise therapy commenced. There are various classes of drugs that are widely prescribed for the treatment of peripheral vascular disease. In this editorial the medical treatment of peripheral vascular disease is claimed to achieve at least one of three goals: (1) improvement of the functional capability; (2) inhibition of the progression of the atherosclerotic and anatomical lesions; (3) reduction of the cardiac and cerebrovascular morbidity and mortality. Guidelines are given for well controlled trials for newly developed drugs for the treatment of peripheral vascular disease in the future.

Arterial Occlusive Diseases↗

PubMed1992

Impaired microcirculation in mild-to-moderate essential arterial hypertension.

OBJECTIVE: The aim of this study was to correlate capillary morphology and erythrocyte velocity to blood pressure in mild-to-moderate essential arterial hypertension. DESIGN: Ambulatory blood pressure measurement may provide more precise information about a patient's mean blood pressure than office measurements. METHODS: Fifteen patients with recently diagnosed, previously untreated mild-to-moderate essential hypertension underwent 24-h ambulatory blood pressure recording and a capillaroscopic examination of finger microcirculation. Erythrocyte velocity was determined by the flying spot technique. RESULTS: Both mean 24-h ambulatory systolic blood pressure (SBP) and mean 24-h ambulatory diastolic blood pressure (DBP) were significantly inversely correlated with capillary erythrocyte velocity. However, the correlation between erythrocyte velocity and office SBP and office DBP was less significant. Capillary length was related to 24-h ambulatory DBP but not to office DBP. Capillary number was not related to any blood pressure parameter. CONCLUSIONS: These results indicate that, in patients with mild-to-moderate essential hypertension, erythrocyte velocity is significantly lower than for matched controls. It is also inversely related to mean 24-h ambulatory SBP and 24-h ambulatory DBP.

Blood Flow Velocity↗

PubMed1992

Examination of Raynaud's phenomenon in traumatic vasospastic disorders.

Certain types of occupation-related vibrations can cause traumatic vasospastic disorders. Findings from clinical examination are often normal at the office consultation. Measurements of finger blood flow using plethysmography while the local ambient temperature is changed can give important information about the severity of traumatic vasospastic disorder and the concomitant disability. This technique can also be used for follow-up of the finger blood flow after withdrawal from vibrations.

Adult↗