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Biomedical subjects

J A Abbott

Publications and source records attributed to J A Abbott.

At least 19 recordsLinked to original sources
PubMed2005

Pathogenesis of ascites in broilers raised at low altitude: aetiological considerations based on echocardiographic findings.

This study reports novel insight into the aetiology of pulmonary hypertension and ascites in broiler chickens. The scope of measurements was focused on anatomical and functional parameters, and blood flow patterns in leghorns (resistant to ascites), fast-growing broilers (susceptible to ascites), broilers developing ascites, and ascitic broilers evaluated in vivo using echocardiography, and further examined in the context of postmortem findings. Both, in vivo observed features and postmortem findings, showed clear differences between broilers and leghorns, and between normal and ascitic broilers. Abnormalities in the heart chamber geometry and blood flow patterns were detected upon echocardiographic examination in all ascitic broilers. Right and left atrio-ventricular (AV) valve regurgitation were common findings in ascitic broilers and some apparently normal broilers, with left AV valve insufficiency being a predominant feature with respect to degree and frequency of occurrence. Blood flow disturbances were not detected in leghorns. Left ventricular fractional shortening (functional parameter) was considerably reduced (P < 0.01) in ascitic birds (mean: 21.7 +/- 2.0 SE) in comparison with normal broilers (mean: 39.1 +/- 3.6 SE), or leghorns (mean: 43.3 +/- 2.4 SE). The presented findings indicate that pathological and functional changes in the left ventricle and atrium play a significant role in the pathogenesis of ascites in broilers. Severe dilation of the left atrium and pulmonary veins seen on postmortem examination, as well as regurgitant blood flow in the left atrium, demonstrated by Doppler study in ascitic birds, provide evidence that chronically elevated pressure in the left atrium is involved in the aetiology of pulmonary hypertension and ascites in fast-growing broilers.

Altitude↗
PubMed2003

Lesions of the pericardium and their significance in the aetiology of heart failure in broiler chickens.

The present study focuses on lesions of the pericardium commonly observed in fast growing broilers. These lesions are examined in the context of electrophysiological and functional changes associated with cardiac performance and patho-physiology in broilers succumbing to acute or chronic heart failure. Typical lesions involving the pericardium in fast growing broiler chickens included: (1) excessive pericardial effusion, (2) locally extensive or focal adhesions between parietal and visceral components of the pericardium, (3) fibrous deposits on visceral pericardium, and (4) thickened pericardium. Echocardiographic evidence indicated that severe pericardial effusion and/or adhesions may have a restrictive effect on heart pump function, where both diastolic and systolic function of the heart may be affected. Electrocardiographic data showed a strong trend indicating that pericardial adhesions may be associated with ventricular arrhythmia and increased risk of sudden death in fast growing broilers. Relatively high levels of matrix metalloproteinase MMP-2 activity have been found in pericardial effusions from affected chickens, suggesting a possible involvement of this enzyme in the aetiology of pericardial lesions. The present results indicate that pericardial lesions may be associated with biochemical, morphological, electrophysiological, and functional changes occurring in the hearts of broilers succumbing to acute or chronic heart failure and ascites.

Animals↗
PubMed2003

The effects and effectiveness of laparoscopic excision of endometriosis: a prospective study with 2-5 year follow-up.

BACKGROUND: This study investigates the outcomes for women up to 5 years after laparoscopic excision of endometriosis. METHODS: In this prospective observational cohort study, 254 women with chronic pelvic pain were referred to two units specializing in minimal access surgical management of endometriosis. Of these, 216 women underwent surgical assessment and 176 were confirmed to have endometriosis. Questionnaires and visual analogue scale (VAS) scores for dysmenorrhoea, non-menstrual pelvic pain, dyspareunia and dyschesia as well as quality of life instruments; the EQ-5Dindex and EQ-5Dvas, Short-Form 12 (SF-12) and sexual activity questionnaires were completed pre-operatively. Intra-operative details of revised American Fertility Society (rAFS) stage, site of disease, associated tests, duration of surgery and complications were noted. Follow-up was performed by postal questionnaire and chart review. For women who had further surgery, rAFS stage, site of disease, other procedures and histology were all recorded. RESULTS: Pain scores were all significantly reduced at 2-5 years for dysmenorrhoea (median VAS baseline versus follow-up 2-5 years); 9 versus 3.3 (P < 0.0001), non-menstrual pelvic pain 8 versus 3 (P < 0.0001), dyspareunia 7 versus 0 (P < 0.0001) and dyschesia 7 versus 2 (P < 0.0001). Quality of life was improved for the EQ-5Dindex (P = 0.008 and the EQ-5Qvas (P = 0.03) and for sexual function with pleasure (P = 0.001) and habit (P = 0.012) being improved and discomfort being decreased (P = 0.001). The chance of requiring further surgery as determined by the Kaplan-Meier survival curve was 36%. A rAFS score of >70 was predictive of requiring further surgery (P = 0.03). Of women who had further surgery, endometriosis was found histologically in 68%. CONCLUSIONS: Laparoscopic excision of endometriosis significantly reduces pain and improves quality of life for up to 5 years. The probability of requiring further surgery is 36%. Return of pain following laparoscopic excision is not always associated with clinical evidence of recurrence.

Adult↗
PubMed1998

Critical care cardiology.

Emergency management of the patient with cardiac disease is an important part of veterinary practice. Although the causes of cardiac disease may be diverse, the understanding of basic pathophysiology will enable the clinician to formulate a rational diagnostic and therapeutic plan. The veterinary clinician must be able to triage the emergency patient, assess the clinical condition, and provide appropriate therapy. Close monitoring of the critically ill patient is crucial to patient survival and will help tailor therapy.

Animals↗
PubMed1992

Usefulness of adenosine in augmenting ventricular preexcitation for noninvasive localization of accessory pathways.

Adenosine was administered to test the hypothesis that it would maximize preexcitation and facilitate noninvasive localization of accessory pathways in 22 patients with suspected accessory pathway-mediated tachycardias. Twelve-lead electrocardiograms and 2-dimensional echocardiograms were recorded at baseline and during adenosine-augmented ventricular preexcitation to localize the accessory pathway. Phase analysis was performed on digitized 4-chamber and short-axis views using a first harmonic Fourier transformation. At baseline, 15 patients had manifest preexcitation. In 14 of these patients (93.3%), preexcitation became more prominent after adenosine. Four patients without preexcitation at baseline clearly had it after adenosine. In patients who had preexcitation in response to adenosine, the electrocardiogram correctly identified the accessory pathway locations in 18 of 19 patients at a regional level and was incorrect in 1 of 19 patients. Echocardiographic phase analysis correctly identified the accessory pathway location in all 17 patients, who had technically adequate studies, at a regional level. In conclusion, administration of adenosine accentuates preexcitation, allowing for more accurate electrocardiographic and echocardiographic accessory pathway localization.

Adenosine↗
PubMed1992

Determination of patch electrode position for the internal cardioverter-defibrillator by cine computed tomography and its relation to the defibrillation threshold.

Cardioverter-defibrillator implantation in 22 consecutive patients after aborted sudden cardiac death was followed by prospective determination of the correct anatomic position of epicardial patch electrodes by chest X-ray study and cine computed tomography; the data were compared with the defibrillation threshold obtained intraoperatively. Patch electrode position was qualitatively graded. Computed tomography improved the assessment as compared with X-ray study in 13 patients (59%), visualizing electrodes in relation to the underlying myocardial and vascular structures. Although the computed tomographic technique provided more precise visualization, its grading of patch position correlated as poorly as that of the X-ray study with the measured acute defibrillation threshold. Three-dimensional reconstruction by computed tomography made it possible to determine quantitatively left ventricular mass (free wall and septum) and the mass encompassed by the patch electrodes. The 34.6 +/- 13.7% (range 12.6 to 61.1%) of the left ventricular mass encompassed by both patch electrodes showed a linear relation to the defibrillation threshold (r = 0.64, p = 0.01). Differentiation of free wall and septal mass in these measurements revealed that the proportion of septal mass encompassed by patch electrodes correlated closely with the defibrillation threshold (r = -0.6, p = 0.019), whereas that of the free wall mass, although significantly larger (35.4 +/- 15.8 vs. 20.6 +/- 15.4 g, p = 0.007), did not. Thus, the position of epicardial patch electrodes could be reliably determined by computed tomography.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Two-dimensional echocardiographic phase analysis. Its potential for noninvasive localization of accessory pathways in patients with Wolff-Parkinson-White syndrome.

BACKGROUND: In patients with the preexcitation syndrome who are undergoing transcatheter or surgical ablation, accurate localization of accessory pathways is critical. Because preexcitation is known to alter ventricular activation sequence and result in focal areas with presystolic contraction, we investigated whether phase analysis applied to two-dimensional echocardiographic cine loops objectively identifies these focal areas and can be used to localize ventricular insertion sites of accessory pathways. METHODS AND RESULTS: We prospectively obtained phase images in 17 patients (11 males; age range, 11-35 years) during minimal preexcitation in normal sinus rhythm and during maximal preexcitation induced by right atrial pacing. A group of 11 normal subjects (six men; age range, 26-37 years) served as controls. Pathway locations predicted from phase imaging were compared with those predicted from routine 12-lead ECGs, from visual inspection of cine loop images, and from catheter-mounted electrode endocardial mapping. Cross-sectional views in a digital cine loop format were mathematically transformed using a first harmonic Fourier algorithm to obtain the corresponding phase images. Phase angle histograms were derived in eight wall segments. Mean and earliest phase angles were derived by computer analysis to quantitate contraction sequence. We found that during right atrial pacing, phase angles in focal areas markedly deviated from normal--mean phase angles from 33 degrees to 164 degrees, and earliest phase angles from 50 degrees to 180 degrees. Accessory pathways could be precisely localized in 53% of the patients by 12-lead ECG, in 59% by visual inspection of cine loop images, in 82% by phase imaging, and in 94% by a combination of the three methods. CONCLUSIONS: Our results suggest that phase imaging, especially when used in combination with cine loop and 12-lead ECG, can be used to localize ventricular insertion sites of accessory pathways and may be clinically useful as a noninvasive adjunct to endocardial mapping in patients with Wolff-Parkinson-White syndrome.

Adult↗
PubMed1991

Relative importance of activation sequence compared to atrioventricular synchrony in left ventricular function.

This study evaluated the relative hemodynamic importance of a normal left ventricular (LV) activation sequence compared to atrioventricular (AV) synchrony with respect to systolic and diastolic function. Twelve patients with intact AV conduction and AV sequential pacemakers underwent radionuclide studies at rest and Doppler echocardiographic studies at rest and during submaximal exercise, comparing atrial demand pacing (AAI) to sequential AV sensing pacing (DDD) and ventricular demand pacing (VVI). Studies at rest were performed at a constant heart rate between pacing modes, and the exercise study was performed at a constant heart rate and work load. Cardiac output was higher during AAI than during both DDD and VVI (6.2 +/- 1 vs 5.6 +/- 1 and 5.3 +/- 1 liters/min, p less than 0.05). LV ejection fraction was likewise higher during AAI (55 +/- 12 vs 49 +/- 11 vs 51 +/- 13, p less than 0.05). VVI with or without AV synchrony was associated with a paradoxical septal motion pattern, resulting in a 25% impairment of regional septal ejection fraction. In addition, LV contraction duration was more homogenous during AAI. Peak filling rate during AAI and VVI was higher than during DDD (2.86 +/- 1 and 2.95 +/- 1 vs 2.25 +/- 1 end-diastolic volume/s; p less than 0.05). During VVI, the time to peak filling was significantly shorter than during both AAI and DDD (165 +/- 34 vs 239 +/- 99 and 224 +/- 99 ms; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Arrhythmia, Sinus↗
PubMed1991

Left atrial volume determination by biplane two-dimensional echocardiography: validation by cine computed tomography.

Left atrial (LA) volume measurements have been made by the application of the method of discs (modified Simpson's rule) to orthogonal biplane atrial echocardiographic images. Validation of the technique has been suboptimal due to deficiencies of the reference standard, levophase angiography. To define the accuracy of echocardiography, we compared LA end-systolic volume by echocardiography in 27 patients with volumes by cine computed tomography (Cine CT), a highly accurate and validated method of measuring cardiac chambers. Echocardiographic tracings were made in the apical long-axis two- and four-chamber views. In patients with atria less than 300 ml, 14 had echoes performed prospectively, with optimization of LA size, while the remaining 10 were analyzed retrospectively. The volume of each slice was calculated and was then summated to obtain total volume. The correlation coefficient between two-dimensional echocardiography and Cine CT was r = 0.98, and it was r = 0.82 when patients with atria greater than 300 ml (n = 3) were excluded. Echocardiography underestimated Cine CT measurements by 23%. The slope of the prospective group was closer to unity than the slope of the retrospective group (p less than 0.001), and the correlation with Cine CT was slightly better for the prospective group (r = 0.88 versus r = 0.77). LA volume by two-dimensional echocardiography correlates closely with Cine CT, a more accurate method of volume determination, and gives valid measurements of LA volume. Efforts to maximize LA size during scanning limit inaccuracies of echocardiographic measurements of the left atrium.

Echocardiography↗
PubMed1991

Phase image triangulation of accessory pathways in patients undergoing catheter ablation of posteroseptal pathways.

The outcome of posteroseptal accessory pathway ablation by direct current (DC) shocks delivered just outside the os of the coronary sinus was studied in 21 patients. Electrocardiographic and electrophysiological parameters as well as phase image patterns of equilibrium multiple-gated blood-pool scintigrams were studied to determine their usefulness in predicting the success of ablation. A second free-wall pathway was documented by electrophysiological or surgical findings in six patients, and the value of phase images in detecting this second pathway was studied as well. Ablation was successful in 57%. The cumulative mean energy of DC shocks amounted to 524 +/- 170 joules and was not predictive of ablation outcome, neither was the mean ventriculoatrial (VA) conduction time. The predictive value of the 12-lead maximally preexcited electrocardiogram was poor in the 15 patients with a single posteroseptal bypass tract. A new method to triangulate the site of the earliest phase angle on the atrioventricular (AV) valve plane successfully localized the bypass pathway in 14 of those patients. No specific phase pattern predicted successful ablation except for a symmetrical, concentric peripheral phase progression found to be predictive of ablation success in the four patients who showed this pattern. Phase analysis was able to localize the second, nonposteroseptal pathway in four of six patients. This study showed that a concentric peripheral phase progression in the gated blood-pool scintigrams is predictive for ablation success in patients with posteroseptal pathways. A free-wall localization of the earliest phase angle is suggestive of a second bypass tract in this area.

Adolescent↗
PubMed1990

Long-term follow-up of patients after transcatheter direct current ablation of the atrioventricular junction.

The long-term follow-up study (41 +/- 23 months) of 47 patients undergoing direct current ablation because of drug-resistant supraventricular arrhythmias is reported. Significant early complications occurred in four patients and included hypotension, pericarditis, nonsustained polymorphic ventricular tachycardia and one sudden death. In 42 patients (86%), complete atrioventricular (AV) block was initially achieved. During the follow-up period, AV conduction resumed in 2 of these 42 patients. Of the seven patients in whom ablation was unsuccessful, two developed late complete AV block and three had symptomatic improvement. An improved activity level was reported among 83% of the patients with successful ablation. Health care utilization manifest as the number of hospital admissions per year before and after ablation decreased significantly after ablation (2.4 +/- 2.0 versus 0.3 +/- 0.5, p less than 0.001). Echocardiographic evaluation in five patients with a depressed left ventricular ejection fraction (27 +/- 7%) before ablation showed a significant increase (45 +/- 14%, p less than 0.05) after an average follow-up period of 31 months. New onset of congestive heart failure occurred after ablation in four patients, of whom two had no structural heart disease. The total mortality rate, including the one patient with sudden death, was 17% and was significantly higher among patients with underlying structural heart disease. Transcatheter direct current ablation is an effective treatment in patients with drug-resistant supraventricular tachycardia, providing a beneficial long-term outcome including an improved quality of life and a decrease in health care utilization.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

Doppler echocardiography and ultrafast cine computed tomography during dynamic exercise in chronic parenchymal pulmonary disease.

In an effort to better understand the cardiac contribution to exercise limitation in chronic lung disease, 21 patients with advanced chronic pulmonary parenchymal disease and 10 normal control subjects were evaluated for changes in right ventricular (RV) pressure, volume and function during incremental, symptom-limited supine bicycle exercise. Patients underwent sequential exercise tests with Doppler echocardiography and ultrafast cine computed tomography (CT). RV systolic pressure during exercise was determined by saline-enhanced Doppler of tricuspid regurgitation. RV ejection fraction, end-diastolic volume, stroke volume and cardiac index were obtained by CT at rest and peak exercise. Sixteen of the 21 study patients also exercised on high-flow oxygen. In the control subjects RV systolic pressure increased from 21 +/- 6 mm Hg (mean +/- standard deviation) at rest to 32 +/- 8 mm Hg at peak exercise, whereas in patients with lung disease, RV systolic pressure increased from 42 +/- 17 to 81 +/- 26 mm Hg (both p less than 0.01). Compared with the control subjects, the patients with lung disease had significantly lower mean values for RV ejection fraction at rest (47 +/- 7 vs 55 +/- 7%) and at peak exercise (47 +/- 9 vs 57 +/- 3%, respectively, both p less than 0.05). The patients who demonstrated oxyhemoglobin desaturation during exercise showed the most abnormal cardiac responses, with marked increases in mean RV systolic pressure, decreases in mean RV ejection fraction and blunted increases in cardiac index and RV stroke volume. Although acute oxygen supplementation was associated with a slight decrease in RV systolic pressure at peak exercise and a longer duration of exercise, there was no significant improvement in RV function. Doppler echocardiography and CT provide complementary and potentially useful information about right-sided heart pressures and RV ejection fraction during exercise in patients with advanced chronic lung disease. Oxyhemoglobin desaturation during exercise is a marker for the most abnormal pulmonary vascular reserve, as indicated by RV contractile dysfunction and limited ability to increase cardiac index.

Aged↗
PubMed1988

Quality assurance review of a rheumatoid arthritis education program.

Quality assurance seeks to measure the degree of compliance to set standards. To determine compliance to a treatment plan of rest, prescribed joint exercise, and medication; 31 rheumatoid arthritis patients were telephoned 3 months after attending a rheumatoid arthritis education program. On follow-up, more than half of the patients reported being compliant. Those that were non-compliant listed reasons related to the affective learning domain rather than lack of cognitive learning.

Adult↗
PubMed1987

Coexistent Mahaim and Kent accessory connections: diagnostic and therapeutic implications.

Six patients with coexistent Mahaim and Kent accessory connections are described. Two had left nodoventricular Mahaim connections, the first reported cases demonstrating these findings. In neither were the left-sided Mahaim connections components of a tachycardia and their presence was incidental. In two of four with nodoventricular connections, associated atrioventricular (AV) node conduction and coexistent posteroseptal accessory pathways were found. One of these had the unusual finding of a right-sided Mahaim connection arising from a "fast" AV node pathway. In only one patient did the tachycardia incorporate the Mahaim connection. In this patient, anterograde conduction during tachycardia occurred over a right nodoventricular connection whereas retrograde conduction occurred through a concealed right free wall Kent connection. Two patients had fasciculoventricular connections that were associated with either septal (one patient) or left free wall (one patient) Kent connections. The latter also had evidence of enhanced AV node conduction. This report is unique in that it describes in detail two patients with left nodoventricular connections (Mahaim) inserting in or near the left posterior fascicle. Combined Kent and Mahaim connections, present in the six patients, appear to occur in approximately 5% of patients with the Wolff-Parkinson-White syndrome. Precise identification of bypass connections critical for reentrant circuits is essential for intelligent application of treatment options.

Adult↗
PubMed1987

Permanent cardiac pacing in patients with the long QT syndrome.

A permanent pacemaker was inserted in eight patients with the long QT syndrome. All had recurrent syncope or seizures, six had documented torsade de pointes and four had aborted sudden death. Among the eight patients, permanent pacing was instituted in three who were unsuccessfully treated with both a beta-adrenergic blocking agent and left cardiothoracic sympathectomy, and in two who proved refractory or intolerant to beta-blockers. Another three patients had pacemaker implantation and long-term beta-blocker therapy because of spontaneous atrioventricular (AV) block in one, aborted sudden death in one and patient preference in one. After pacing (70 to 85 beats/min), there was no significant change in the mean corrected QT interval, but the mean QT interval decreased significantly (534.4 +/- 51.4 to 425.6 +/- 18.9 ms, p less than 0.0001). Over a mean follow-up period of 35.1 +/- 18.9 months, all patients are alive and currently free of syncope. One patient without a history of stress-induced syncope had two syncopal episodes (believed to be due to hyperventilation) while under severe emotional stress, but has been symptom free for the past 5 years. One patient with an atrial demand (AAI) pacemaker developed dizziness due to documented episodes of AV block, but remains asymptomatic after conversion to atrial rate-responsive dual chamber (DDD) pacing. Either atrial or ventricular pacing combined with beta-blocker therapy appears to be effective treatment for a subset of patients with the long QT syndrome, by either preventing episodes of torsade de pointes or alleviating symptoms due to bradycardia from beta-blocker therapy.

Adolescent↗
PubMed1986

Procainamide-induced incessant supraventricular tachycardia in the Wolff-Parkinson-White syndrome.

A patient with the Wolff-Parkinson-White syndrome presented with incessant orthodromic atrioventricular tachycardia following initiation of procainamide therapy. This finding was repeatedly documented both clinically as well as during electrophysiologic testing. Escape atrial complexes, which occurred following junctional premature complexes, failed to initiate tachycardia in the control state but tachycardia was always reinitiated by an identical escape sequence after procainamide. In addition, the tachycardia persisted and was repeatedly spontaneously reinitiated for prolonged periods after procainamide. The pro-arrhythmic effects of procainamide may be explained on the basis of both its vagolytic action on the atrioventricular node as well as by prolongation of refractoriness in the accessory pathway. These observations add to the literature on pro-arrhythmic effects of commonly used antiarrhythmic drugs.

Electrophysiology↗