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Biomedical subjects

S Faerestrand

Publications and source records attributed to S Faerestrand.

At least 19 recordsLinked to original sources
PubMed2004

Reverse remodelling of systolic left ventricular contraction pattern by long term cardiac resynchronisation therapy: colour Doppler shows resynchronisation.

OBJECTIVE: To quantify long term effects of cardiac resynchronisation therapy (CRT) by biventricular pacing in patients with heart failure (HF). METHODS: Regional changes in left ventricular (LV) contraction patterns effected by CRT in 19 patients with HF (12 with ischaemia; mean (SD) age 66 (9) years) with bundle branch block were examined by colour Doppler tissue velocity imaging (c-TVI). Time differences during main systolic tissue velocity peak (SYS) were compared in the basal and mid LV interventricular septum and in the corresponding LV free wall segments. RESULTS: From baseline to long term (9.8 (3.0) months) CRT, ejection fraction increased from 21.8 (5.4)% to 30.8 (7.6)%, LV end diastolic diameter decreased from 7.6 (0.9) cm to 7.1 (0.8) cm, and end systolic diameter decreased from 6.4 (1.2) cm to 6.0 (1.2) cm (p < 0.05). LV peak tissue velocities were unchanged during follow up. At baseline, SYS in LV free wall was typically delayed by an average of 29 ms in the basal LV site and by 18 ms in the mid LV site. The regional movements of the LV free wall and interventricular septum were separated by an average of only 14 ms and -4 ms (p < 0.05) at the basal site and by -21 ms and -16 ms at the mid LV site during short term and long term CRT, respectively. CONCLUSIONS: The improved haemodynamic functions observed during CRT may be explained by a significant resynchronisation of the regional LV movement pattern during long term follow up.

Aged↗
PubMed2003

Colour tissue velocity imaging can show resynchronisation of longitudinal left ventricular contraction pattern by biventricular pacing in patients with severe heart failure.

OBJECTIVE: To quantify ventricular resynchronisation by biventricular pacing using colour tissue Doppler velocity imaging (c-TVI). DESIGN AND PATIENTS: c-TVI shows regional tissue velocity profiles with a very high time resolution (10 ms). Eighteen patients were studied from an apical four chamber view at baseline and after a one month follow up of biventricular pacing. Regional left ventricular peak tissue velocities and regional time differences during the cardiac cycle were compared in the basal and mid interventricular septal segments of the left ventricle, and in the corresponding segments in the left ventricular free wall. RESULTS: From baseline to follow up, mean peak tissue velocities changed only during isovolumic contraction in the basal interventricular septum and the left ventricular free wall. At baseline the peak main systolic tissue velocities in the left ventricular free wall were typically delayed by an average of 42 ms in the basal left ventricular site and by 14 ms in the mid left ventricular site compared with the corresponding sites in the interventricular septum. After resynchronisation by biventricular pacing those regional movements were separated by an average of only 7 ms at the basal site, but there was still a 21 ms earlier movement of the left ventricular free wall in the mid left ventricular site. The diastolic movement pattern remained unchanged from baseline to follow up. CONCLUSIONS: c-TVI showed a significant asynchronous regional longitudinal movement of basal left ventricular sites at baseline. A change to a more synchronous longitudinal left ventricular movement pattern during biventricular pacing was demonstrated.

Atrial Fibrillation↗
PubMed2003

The effect of body weight on the degree of blood velocity profile skewness in the aortic annulus in domestic pigs.

We investigated the blood velocity profile in the aortic annulus (AA) in two groups of domestic pigs using epicardial Doppler echocardiography. The velocity profile skewness in terms of max/mean TVI (the ratio of maximal to cross-sectional mean time-velocity integral along the diameter) was 1.107 +/- 0.01 in the small pigs (n = 10; body weight: 24.6 +/- 0.8 kg) and 1.216 +/- 0.026 in the large pigs (n = 8; body weight: 50.6 +/- 2.5 kg) (P = 0.002). The velocity profile in the AA is more skewed in large animals than in small animals and the skewness in the larger animals is similar to that in normal adult humans. This study shows the importance of choosing animals of sufficient size if flow method investigations are to be performed. This is particularly important for ultrasound Doppler investigations based on a limited sample of velocities across the flow channel.

Animals↗
PubMed2001

[Biventricular pacemaker treatment of patients with severe heart failure].

BACKGROUND: Biventricular pacing using a pacemaker lead located epicardially on the left ventricle, introduced via the coronary sinus to a coronary vein, and one pacemaker lead located endocardially at the apex of the right ventricle can resynchronize the contraction of the left ventricle. Approximately 30-50% of patients with severe heart failure have left bundle branch block indicating asynchronous contraction of the left ventricle. These patients can have a significant haemodynamic benefit from biventricular pacing. MATERIAL AND METHODS: The methods for implanting the leads are described. Biventricular pacemakers were implanted in five patients. RESULTS: Acceptable low thresholds for pacing the left ventricle were achieved. Resynchronization of the contraction of the left ventricle was demonstrated by using colour tissue Doppler measurements. The mechanisms for the haemodynamic benefit of biventricular pacing are discussed on the basis of our data. The first patient has been followed for 12 months. He has a lasting improvement in functional capacity from class IV to class II, marked reduction of the left ventricular size, and improvement of the left ventricular ejection fraction from 15% to 38%. INTERPRETATION: The results are promising for patients who, because of lack of donor hearts and age criteria, often cannot be offered heart, transplantation.

Adult↗
PubMed2001

[Atrial flutter--diagnosis and therapeutic possibilities].

BACKGROUND: Atrial flutter and atrial fibrillation are among the most common heart rhythm disturbances in the population, with an assumed prevalence of 1-2%. About 40,000-60,000 Norwegians endure such rhythm disorders, with an increasing occurrence in the elderly population. MATERIAL AND METHODS: Surface ECG remains the corner-stone for the clinical diagnosis. We describe the various mechanisms, clinical presentation, and diagnosis based on modern invasive electrophysiological methods of atrial flutter. RESULTS: The available therapeutic modalities for conversion during episodes and prophylaxis with drugs, various pacing techniques, DC conversion and surgical therapy are discussed. INTERPRETATION: Radiofrequency catheter ablation is the only available method to cure the patient in a gentle manner.

Anti-Arrhythmia Agents↗
PubMed2001

[Radiofrequency catheter ablation of atrial flutter].

BACKGROUND: The anatomical structure of atrial flutter is now well recognized, and treatment with radiofrequency catheter ablation (RFA) is established. Several recording and ablation techniques can be applied. MATERIAL AND METHODS: An increasing number of patients have been treated with RFA at the Arrhythmia Centre at Haukeland University Hospital over the last six years. During the two-year period 1999 and 2000, a total of 108 procedures were performed for atrial flutter in a total of 84 patients. A total of 543 RFA procedures for various forms of re-entry tachycardias were performed during the same period; hence, atrial flutter comprised about 20% of RFA procedures. Altogether 71 men and 14 women with a mean age of 57 +/- 12 years were treated. The mean history of atrial flutter had a duration of nine years, maximum 43 years with several hospital admissions, drug trials, overdrive pacing and DC conversion until they were ultimately cured with RFA. RESULTS: The success rate during first time treatment was 96.5%. No serious complications were observed. INTERPRETATION: RFA should be the treatment of first choice in patients with recurrent or incessant atrial flutter.

Adult↗
PubMed1998

Atrial synchronous ventricular pacing with a single lead: reliability of atrial sensing during physical activities, and long-term stability of atrial sensing.

A VDD pacing system with bipolar single-pass leads, were implanted in 36 consecutive patients (average age 72 +/- 2 years) with high degree atrioventricular block and normal sinus node function. At implant the atrial signal amplitude was 2.6 +/- 0.2 mV measured by a pacing system analyser (PSA), 1.8 +/- 0.1 mV measured peak-to-peak from the telemetered calibrated electrogram, and 1.3 +/- 0.1 mV measured from the sensing threshold. At one month follow-up the peak-to-peak amplitudes (mV) of the telemetered atrial electrograms were not significantly different measured continuously during resting supine with quiet breathing (1.4 +/- 0.1), sitting (1.6 +/- 0.2), standing (1.5 +/- 0.1), arm swinging (1.4 +/- 0.2), hyperventilation (1.3 +/- 0.1), Valsalva manoeuvre (1.4 +/- 0.1), and treadmill exercise (1.9 +/- 0.6). The telemetered atrial electrogram amplitude and the atrial sensing threshold varied between 1.2 +/- 0.09 mV and 1.8 +/- 0.1 mV, and between 0.95 +/- 0.07 mV and 1.3 +/- 0.01 mV, respectively at 0.5, 1, 3, 6 and 12 months follow-up, but the changes were statistically non-significant. The Event Summary showed sensing of 98% to 99% of the atrial events at the different follow-up periods.

Aged↗
PubMed1997

Effects of velocity distribution, diameter measurement and velocity tracing on the accuracy of cardiac output measurement by pulsed Doppler echocardiography in the aortic annulus of pigs.

UNLABELLED: The accuracy of cardiac output measurement by pulsed Doppler echocardiography can be affected by several factors, such as the velocity distribution, the measurement of diameter and the method of tracing the pulsed Doppler flow spectrum. This experimental study was designed to find the most accurate way of measuring cardiac output in consideration of all these factors. In 10 open-chest normal piglets (24 +/- 1 kg), the velocity distribution in the aortic annulus was evaluated using Doppler colour flow mapping. Cardiac output was measured by pulsed Doppler echocardiography in the aortic annulus by a number of different ways and compared to the simultaneous result of the thermodilution method. All measurements were made at baseline, after intravenous injection of esmolol and during infusion of dobutamine. RESULTS: (1) the velocity distribution in the aortic annulus in the piglets was just slightly skewed during all three haemodynamic situations; (2) The in vivo measurements of the diameter of the aortic annulus varied throughout the ejection period, but the average of the three largest diameter measurements was almost identical with the diameter measured in vitro (18.5 +/- 0.3 mm vs. 18.6 +/- 0.2 mm; p = NS); (3) Tracing the maximal velocity of the pulsed Doppler flow spectrum produced a cardiac output that was 18%-21% higher than that measured by the thermodilution method, while tracing the brightest part (modal velocity) of the pulsed Doppler flow spectrum yielded a cardiac output very close to the thermodilution measurement. CONCLUSION: The velocity distribution in the aortic annulus in the piglet has little effect on cardiac output measurement by pulsed Doppler. Using the maximal measurable diameter of the aortic annulus and tracing the brightest part of the pulsed Doppler flow spectrum yielded the cardiac output closest to that measured by the thermodilution method.

Adrenergic beta-Antagonists↗
PubMed1996

Flow velocity distributions in the left ventricular outflow tract and in the aortic annulus in patients with localized basal septal hypertrophy.

BACKGROUND: The velocity distributions in the left ventricular outflow tract and in the aortic annulus in normal subjects and certain cardiac patients are skewed, with the highest velocity along the anterior wall and septum. An abnormal anatomical structure of the interventricular septum changes the shape of the left ventricular outflow tract, and may consequently change the pattern of velocity distribution. METHODS: The cross-sectional velocity distributions in the left ventricular outflow tract and in the aortic annulus were constructed by using Doppler colour flow mapping in nine patients with localized basal septal hypertrophy, and in 10 normal subjects. The apical long axis view was used. RESULTS: In the studied patients, the velocity distributions in the left ventricular outflow tract and in the aortic annulus were skewed in a different way from those in normal subjects. The relative location of the maximal velocity on the cross-sectional diameter of the flow channel changed from one level to another. At the point of maximal basal septal hypertrophy, the velocity distribution was most skewed with the highest velocity along the anterior wall (e.g. basal septum). Distal to this level, the highest velocities of the skewed velocity profiles were gradually located closer to the central part of the flow channel. According to the time-velocity integral profile at the level of the aortic annulus, the pattern of skewness (in terms of the difference of the average time-velocity integrals between the anterior and posterior halves of the diameter) was significantly different between the normal and patient groups (5.51 +/- 3.55 cm vs 0.03 +/- 2.07 cm; P < 0.01), while the extent of skewness (in terms of the ratio of the maximal to the cross-sectional mean time-velocity integrals) was close between two groups (1.36 +/- 0.28 vs 1.27 +/- 0.13; P > 0.05). CONCLUSION: Localized basal septal hypertrophy significantly affects velocity distributions in the left ventricular outflow tract and in the aortic annulus.

Adult↗
PubMed1995

Velocity distributions in the left ventricular outflow tract in patients with valvular aortic stenosis. Effect on the measurement of aortic valve area by using the continuity equation.

UNLABELLED: The cross-sectional velocity distribution in the left ventricular outflow tract was studied in 40 patients with valvular aortic stenosis. Doppler colour flow mapping and a time-interpolation method were used to construct the cross-sectional velocity and time-velocity integral (TVI) profiles at different levels. By using pulsed Doppler, the subaortic flow velocity was sampled from the anterior, middle and posterior regions along the diameter of the left ventricular outflow tract (at 0.5 to 1.0 cm proximal to the aortic anulus) in the apical long axis view. Thus, for each patient, three aortic valve areas were calculated by using the continuity equation. Each patient was assigned to one of three subgroups according to the left ventricular ejection fraction (EF): subgroup I with EF < or = 25% (n = 10), subgroup II with 25% < EF < or = 50% (n = 17) and subgroup III with EF > 50% (n = 13). Velocity distributions in the three subgroups were compared to each other. RESULTS: (1) The velocity distribution in the left ventricular outflow tract was skewed with the highest velocities and TVIs along the anterior wall and septum. The skewness of the velocity distribution was more pronounced in the apical long axis view than in the four chamber view (P < 0.05). The extent of skewness of the TVI profile was positively correlated to the left ventricular EF both in the long axis view (r = 0.63; P < 0.001) and in the four chamber view (r = 0.57; P < 0.001). (2) Pulsed Doppler sampling from different regions along the diameter produced different TVIs, and therefore yielded significantly different calculated aortic valve areas, especially in subgroup III. Due to the skewness of the velocity distribution in the left ventricular outflow tract, location of the pulsed Doppler sample volume significantly affects the accuracy of aortic valve area calculation by using the continuity equation, especially in patients with relatively high left ventricular EF. In patients with low EF, selection of pulsed Doppler sampling site is less important.

Aged↗
PubMed1995

The velocity distribution in the aortic annulus at different times during systole is mainly determined by the pattern of flow convergence in the left ventricular outflow tract--an experimental study using Doppler colour flow mapping.

An experimental study in 10 open chest normal pigs (body weight: 24 +/- 1 kg) was carried out to explore the relationship between the velocity distribution in the aortic annulus and the pattern of flow convergence in the left ventricular outflow tract. The cross-sectional velocity profiles in the aortic annulus were constructed by using Doppler colour flow mapping with a previously validated time-interpolation method. The pattern of flow convergence in the left ventricular outflow tract was quantified by measuring the colour flow areas on the anterior and posterior sides of the central axis of the aortic annulus, and calculating their difference. The dynamic changes of the velocity distribution, the pattern of flow convergence and the septal angle throughout systole were observed. The velocity distribution in the aortic annulus changed according to the pattern of flow convergence in the left ventricular outflow tract. During early systole, the pattern of flow convergence was most asymmetrical. With the central longitudinal axis of the aortic annulus as a reference, the main part of the converging flow was along the anterior wall of the left ventricular outflow tract. Consequently, the velocity profile in the aortic annulus was most skewed during the early systole, with the highest velocity along the anterior wall. Towards late systole, the pattern of flow convergence became more and more symmetrical, and the velocity distribution in the aortic annulus gradually became flat. A significant correlation was found between the extent of asymmetry of the pattern of flow convergence in the left ventricular outflow tract and the extent of skewness of the velocity distribution in the aortic annulus (r = 0.69, P < 0.001). Throughout systole, septal angle increased very slightly (from 35 +/- 3 to 38 +/- 3 degrees, P < 0.01). The pattern of flow convergence in the left ventricular outflow tract is a major determinant of the velocity distribution in the aortic annulus in pigs.

Animals↗
PubMed1994

Myocardial contraction patterns in non-ischaemic and ischaemic regions during acute coronary insufficiency.

The effect of coronary insufficiency on the myocardial contraction pattern was studied in 11 thoracotomized cats using apical long axis echocardiograms and cross-oriented segments in the anterior midwall. Myocardial tissue blood flow was studied using radiolabelled microspheres. After circumflex coronary artery occlusion, ejection shortening increased on average 17% for circumferential segments (P < 0.05) and 61% for longitudinal segments (P < 0.001). Hyperkinesis was also validated as augmented anterior endocardial wall motion and wall thickening. Circumflex occlusion increased end-systolic sphericity of the left ventricle (P < 0.05). Subsequent underperfusion of the left coronary artery, in two discrete steps, decreased subendocardial blood flow by, on average, 36% (P < 0.001) and 75% (P < 0.001) vs the post-occlusion value, while subepicardial flow did not change. While subendocardial blood flow decreased by 36%, systolic shortening of the global major axis decreased, by, on average, 77% (P < 0.001), shortening of the longitudinal segments by 36% (P < 0.001), and systolic shortening of the minor axis by 18% (P < 0.05), whereas shortening of midwall circumferential segments did not change. This study shows that changes in myocardial contraction in both non-ischaemic and ischaemic regions during coronary insufficiency are most pronounced in the direction of the cardiac major axis.

Acute Disease↗
PubMed1994

Long-term clinical performance of a central venous oxygen saturation sensor for rate adaptive cardiac pacing.

Rate adaptive ventricular pacemakers using central venous oxygen saturation (O2Sat) to control the pacing rate have been implanted in 14 patients (mean age 71 years), with a mean follow-up period of 44 months (range 2-63 months). In eight patients the pacemakers were replaced due to signs of battery depletion after an implant duration of 39-58 months. During bicycle exercise testing the O2Sat decreased on average from 61% +/- 4% at rest to 36% +/- 4% (P < 0.0001) at peak exercise, and the maximum pacing rate was 122 +/- 5 beats/min. The time delay until the O2Sat had dropped 10%, 65%, and 90% of the total reduction during exercise was 4.8 +/- 0.9 seconds, 39.8 +/- 3.8 seconds, and 71.3 +/- 7.5 seconds, respectively. The O2Sat decreased 9.4% +/- 2% (P < 0.005) from resting supine to resting sitting. Oxygen breathing increased the telemetered O2Sat from the pacemaker by 8.4% +/- 1% (P < 0.001). During follow-up the O2Sats were relatively stable in 50% of the patients, but demonstrated significant fluctuations in the others. At 1-year invasive follow-up O2Sat measured by the pacemaker decreased 22% +/- 2%, and in blood samples from the right ventricle 22% +/- 2% from rest to 3 minutes exercise at 25 watts. There was a significant correlation between O2Sat measured by the pacemaker and in blood samples from right ventricle (n = 105; r = 0.73; P < 0.001). In two patients the O2Sat dropped significantly during pneumonia. In another patient episodes of angina pectoris was associated with low O2Sat and a concomitant fast pacing rate.

Aged↗
PubMed1993

[Treatment of ventricular tachyarrhythmias with an implantable pacemaker-cardioverter-defibrillator].

During the period from November 1989 to January 1992, 17 patients with ventricular tachyarrhythmias received an implantable pacemaker-cardioverter-defibrillator. The material consists of three female and 14 male patients with an age range of 13-66 years, mean 50.8 +/- 16.6 years. 13 patients had coronary artery disease, one cardiomyopathy, one a myocarditis sequela and two primary rhythm disorder. Four patients received epicardial and 13 endocardial electrode systems. The observation period varied from 4-30 months (april 1992), mean 15.2 +/- 8.8 months. 11 out of 17 patients (65%) experienced one or more episodes of tachyarrhythmias which was treated successfully with overdrive pacing (ramp or burst), cardioversion or defibrillation. One patient died of heart failure after an observation period of 13 months. His pacemaker-cardioverter-defibrillator had been activated more than 100 times. Two children, 13 and 15 years, were treated successfully for ventricular fibrillation four and five months after implantation of the device. The actual one year survival is 100%. Assuming that therapy with a device had not taken place, and that the six patients who experienced episodes of ventricular fibrillation died, the hypothetical probability of survival would have been 62.1 +/- 12.3%.

Adolescent↗
PubMed1993

Velocity distributions in the left ventricular outflow tract and the aortic anulus measured with Doppler colour flow mapping in normal subjects.

This study was designed to investigate the velocity distributions in the left ventricular outflow tract and aortic anulus. In 18 out of 22 healthy male individuals, instantaneous cross-sectional flow velocity profiles were constructed at different levels of the left ventricular outflow tract and aortic anulus by time interpolation of digital velocity data from sequentially delayed Doppler colour flow maps. The results showed that: (1) the velocity distributions in the left ventricular outflow tract and the aortic anulus were skewed with the highest velocities along the anterior and septal parts of the flow channel; (2) based on the time-velocity integral profiles in the aortic anulus, which were also skewed with the highest integrals along the anterior and septal parts, the maximal time-velocity integrals were higher than the mean cross-sectional time-velocity integrals by approximately 30% in the four chamber view and 40% in the long axis view. However, the time-velocity integrals at the middle point of the diameter correlated significantly with the mean cross-sectional time-velocity integrals in the four chamber view (10.3 +/- 0.8 vs 9.9 +/- 0.9 cm; r = 0.95) and in the long axis view (12.5 +/- 0.9 vs 11.8 +/- 0.8 cm; r = 0.95). Therefore, it can be concluded that: (1) the velocity distributions in the left ventricular outflow tract and the aortic anulus are skewed; (2) if the aortic anulus is used for cardiac output measurement by pulsed Doppler echocardiography in normal subjects, the middle point of its diameter is the best sampling site.

Adult↗
PubMed1993

Changes in myocardial contraction patterns in response to regional ischemia and sympathetic nerve stimulation.

We studied the effect of inferior cardiac nerve stimulation on global and regional left ventricular function before and after circumflex coronary arterial (CFX) occlusion in 12 pentobarbital-anesthetized cats. Regional function was evaluated by orthogonal sonomicrometry in the anterior midwall of the left ventricle and by two-dimensional short-axis echocardiography. CFX occlusion provoked hypokinesis in the nonischemic free wall adjacent to the dyskinetic ischemic region (17.6 +/- 2.3 vs. 34.6 +/- 2.2% preocclusion wall thickening; P < 0.01) and gradually improved systolic wall thickening toward the contralateral remote region, where the maximal hyperkinetic response was measured (52.9 +/- 4.4 vs. 32.5 +/- 3.3% preocclusion wall thickening; P < 0.001). In the anterior wall, remote region, hyperkinesis was predominant in longitudinal segments (8.1 +/- 0.8 vs. 2.3 +/- 0.6% preocclusion ejection shortening; P < 0.001) and slight in circumferential segments (11.0 +/- 0.7 vs. 9.1 +/- 0.6% preocclusion ejection shortening; P < 0.01). The postocclusion systolic wall thickening and segment-shortening pattern were not modified by sympathetic nerve stimulation, which increased cardiac output less after coronary occlusion, although contractility (dP/dt) increased markedly. In conclusion, the myocardial contraction pattern in ischemic and nonischemic regions after CFX occlusion is not much modified by sympathetic cardiac nerve stimulation.

Animals↗