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Biomedical subjects

A J Dunning

Publications and source records attributed to A J Dunning.

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

Prediction of apical thrombus formation in acute myocardial infarction based on left ventricular spatial flow pattern.

The predictive value of the left ventricular spatial flow pattern for thrombus formation was determined in 62 patients with acute myocardial infarction. A normal flow pattern by pulsed Doppler echocardiography was characterized by 1) simultaneous onset of blood motion at the mitral valve and apical level, and 2) a discontinuous Doppler signal along the lateral wall and interventricular septum. The flow pattern was assessed by these criteria, within 24 h after the onset of complaints and after 6 and 12 weeks. In 46 of the 62 patients, a normal flow pattern was found at the first examination; none of these 46 patients developed a thrombus during the study period. An abnormal flow pattern was seen at the first examination in 16 patients; this pattern normalized during follow-up in 6 patients, none of whom developed a thrombus. In the other 10 patients the abnormal flow pattern persisted, and 7 of these developed a thrombus. These findings suggest that a normal left ventricular flow pattern in the setting of acute myocardial infarction is not associated with subsequent thrombus formation. This observation may be of importance if anticoagulation is considered.

Aged↗
PubMed1990

Body surface mapping during percutaneous transluminal coronary angioplasty. QRS changes indicating regional myocardial conduction delay.

Using a radiotransparent electrode array, body surface maps (BSMs) were constructed based on simultaneous recordings from 62 leads on the entire thorax before, during, and after balloon inflation during percutaneous transluminal coronary angioplasty (PTCA). Twenty-five patients were studied, and 30 angioplasties were performed; 20 patients had one-vessel disease, and five patients had two-vessel disease. In total, 15 dilations in the left anterior descending artery (LAD), seven in the right coronary artery (RCA), and eight in the left circumflex artery (LCx) were studied. For each patient, the BSM and the QRS integral map before, during, and after the inflation was compared by subtraction of recordings "during-minus-before" inflation and "before-minus-after" inflation. The subtraction was performed on the results of the QRS integral maps. The conclusions derived from the inspection of the BSMs and the difference maps show specific changes in the QRS complex during ischemia related to the corresponding ischemic segment in 21 of 25 patients in the three groups. An area of positive potentials remained present on the BSM during dilation, indicating a depolarization wave front. For the LAD group, positive potentials were seen on the anterior thorax and, for the RCA group, on the lower part of the thorax. By subtraction analysis, these changes were extracted and presented as difference maps. For the LCx group, the BSM revealed no changes in pattern but the difference map showed a difference vector pointing in a anteroposterior direction. A regional myocardial conduction delay was hypothesized as the most likely cause for the results.

Adult↗
PubMed1990

Body surface mapping of ectopic left and right ventricular activation. QRS spectrum in patients without structural heart disease.

The value of simultaneous 62-lead electrocardiographic recordings in localizing the site of origin of ectopic ventricular activation in a structurally normal heart was assessed by examining body surface QRS integral maps in 12 patients during left and right ventricular (LV and RV) pacing at 182 distinct endocardial sites. A data base of 38 characteristic mean integral maps was composed after visually selecting subgroups with nearly identical total QRS integral morphology and numerically evaluating intrasubgroup pattern uniformity and intersubgroup pattern variability. Corresponding endocardial pacing site locations were computed by a biplane cineradiographic method and outlined as segments on a standardized LV and RV polar projection. LV pacing resulted in 25 markedly different mean total QRS integral patterns, showing higher electrocardiographic sensitivity for anteroseptal (18 patterns) compared with posterolateral regions (seven patterns). RV pacing demonstrated 13 mean total QRS integral patterns, exhibiting less intersubgroup variation and comparatively low electrocardiographic sensitivity for the basal anterior and outflow regions. Comparison of LV with RV pacing revealed that QRS configurations produced at LV apical and LV midseptal sites closely resembled QRS configurations generated at RV apical, RV septal, and RV anterior sites, respectively. Total QRS time integral amplitudes showed considerable intrasubgroup variation but permitted global differentiation of spatially similar QRS patterns obtained during pacing at LV and RV sites. This study demonstrates that the QRS pattern of the total body surface electrocardiogram allows discrimination among 38 different LV and RV segments of ectopic endocardial impulse formation in patients with normal cardiac anatomy.

Adult↗
PubMed1990

Intraoperative transesophageal color-coded Doppler echocardiography for evaluation of residual regurgitation after mitral valve repair.

Because mitral valve competence after mitral valve reconstruction is awkward to assess during this procedure, we evaluated in this respect transesophageal color-coded Doppler echocardiography in 23 patients undergoing mitral valve reconstruction for severe mitral regurgitation. Transesophageal echocardiographic examinations were performed after induction of anesthesia but before sternotomy (baseline), after mitral valve repair before decannulation, and at sternal closure, all at similar mean aortic pressure and echocardiographic instrument settings. The degree of mitral regurgitation by transesophageal color Doppler flow mapping was visually quantified on a 5-point scale (0 to 4), pending the left atrial extent of the regurgitant jet. This was compared with the degree of mitral regurgitation by left ventricular cineangiography performed within several weeks after operation and also visually quantified on a 5-point scale (0 to 4), with use of the right anterior oblique projection. There was good correlation between the two methods (r = 0.83; p less than 0.001). We conclude that residual mitral regurgitation, as assessed by transesophageal color flow mapping in the operating room, highly correlates with the ultimate mitral regurgitation by cineangiography. Therefore transesophageal echocardiography can be helpful for evaluation of mitral valve competence during mitral valve reconstruction, and hence, in case of repair failure, allow valve replacement in the same surgical session, thus avoiding reoperation.

Adolescent↗
PubMed1989

[Angiodysplasias in the digestive tract and associated cardiovascular diseases].

To clarify the possible relationship between angiodysplasia of the gastrointestinal tract and cardiovascular disease, we performed a retrospective study of 58 consecutive patients. In all patients angiodysplasias were identified endoscopically. The median age was 72 years. Fifty-seven per cent of the patients had some clinically obvious cardiovascular disorder. Mitral valve insufficiency was found more often (21%) than aortic valve stenosis (10%). A high incidence of coronary artery disease (45%) and peripheral artery disease (10%) was noted. These findings do not support the concept that angiodysplasia occurs principally in combination with aortic stenosis. The aetiology of these vascular lesions is presumably multifactorial. The vast majority of the lesions seems to be acquired and at least a subgroup is probably an expression of degenerative processes of aging.

Adult↗
PubMed1989

Predictive value of indium-111 antimyosin uptake for improvement of left ventricular wall motion after thrombolysis in acute myocardial infarction.

In 21 patients treated with thrombolysis for acute myocardial infarction (AMI), the degree of myocardial uptake of indium-111 monoclonal antimyosin antibodies injected within 24 hours after onset of AMI was compared with the degree and extent of regional asynergy on admission and discharge, as assessed by 2-dimensional echocardiography. On the first day of AMI, 80 MBq of indium-111 antimyosin was injected and planar images were made 24 hours later. Indium-111 antimyosin uptake was evaluated for count density index (count density of infarct zone/left lung count density) in the left anterior oblique projection, in which the infarction zone was well displayed in all patients. Using 2-dimensional echocardiography, the left ventricle was divided into 13 segments and evaluated for regional asynergy, which was considered severe (akinesia or dyskinesia) or mild (hypokinesia). The extent of regional asynergy was measured by the number of asynergic segments. All 21 patients had severe regional asynergy on admission. Nine of 21 showed only mild regional asynergy on discharge and 12 of 21 had persistent severe regional asynergy in at least 1 segment. The count density index was significantly lower in patients with mild regional asynergy on discharge compared with patients with severe regional asynergy (1.63 +/- 0.27 vs 2.50 +/- 0.42, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Comparison of transthoracic and transesophageal color Doppler flow imaging in patients with mechanical prostheses in the mitral valve position.

This study determined the relative value of transthoracic and transesophageal color Doppler flow imaging to systolic flow patterns in the left atrium in different types of mechanical prostheses in the mitral valve. Thirty-nine patients were investigated. Based on clinical findings, 36 of 39 patients had normal prosthetic valve function. Seventeen patients were interrogated within a few days after surgery. Systolic regurgitant jets in the left atrium were absent in all patients by both transthoracic pulsed and color Doppler flow imaging. Using transthoracic continuous wave Doppler, however, jets were demonstrated in 8 of 39 patients (21%). Transesophageal color Doppler flow imaging demonstrated systolic regurgitant jets originating from the prosthesis in all patients. Tilting disc valves showed jets during the entire systole (closure and leakage backflow). Each type of prosthesis generated a specific jet pattern. Pathologic regurgitant jets were crescent-shaped, more extensive and turbulent than jets caused by normal closure and leakage backflow. Thus, transthoracic color Doppler flow imaging is not sensitive for detecting regurgitant jets in mechanical prostheses in the mitral valve. All mechanical prostheses show a specific jet pattern, which should be helpful when transesophageal echocardiography is used to identify pathologic backflow.

Adult↗
PubMed1989

[The Public Health Council advice on heart transplantation; the price of progress].

The final report of the Health Council of The Netherlands on cardiac transplantation clearly demonstrates the success of the national program since 1984, after the first transplant. The 122 patients receiving transplants up till December 1988 have a good survival rate and quality of life, comparable in efficacy and costs with treatment of end-stage renal failure. The price of progress, however, must be paid. Donor organ shortage will limit expansion and costs will be competing with other health care needs, when cardiac transplantation is made available on a wider basis. Implications for patients, doctors and government are discussed.

Cost-Benefit Analysis↗
PubMed1989

Nicardipine for preservation of myocardial metabolism and function in patients undergoing coronary artery surgery.

The present study was designed to evaluate the myocardial protective effect of nicardipine (NIC) in patients with normal left ventricular (LV) function (control vs. NIC treatment group) and impaired LV function (control vs. NIC treatment group) during extracorporeal circulation for coronary artery surgery. NIC infusions were begun approximately 12 min before aortic cross clamping (AoX) at an infusion rate of 5 micrograms.kg-1.min-1 and maintained for 10 min. Prior to AoX an additional bolus of NIC 5 mg was given. Coronary hemodynamics, myocardial metabolic parameters (continuous thermodilution), and regional LV function (two-dimensional transesophageal echocardiography) were measured. At 15 min after discontinuation of AoX, lactate production was found in the two control groups but not in the two NIC treatment groups. In the control groups, lactate production returned to extraction at sternal closure. At that time regional area ejection fraction (RAEF) had significantly improved in both groups with impaired LV function compared with postintubation (baseline) values. In NIC-treated patients with impaired LV function, however, the percentage improvement in RAEF was significantly greater than that in the control groups. Between the groups, there were no differences in the number of patients requiring inotropic support, pacing, and/or diuretics after bypass or postoperatively. There were no significant differences in postoperative creatine kinase myocardial band release or in the incidence of dysrhythmias, myocardial infarction, or mortality. The results of the present study suggest that NIC iv may be used to provide additional myocardial protection during extracorporeal circulation. In addition, in NIC-treated patients with compromised LV function, this may be associated with a more apparent improvement in RAEF than that seen in nontreated patients.

Aged↗
PubMed1988

Phasic flow in the left ventricular inflow tract: the importance of Doppler sample volume position.

Variability of Doppler transmitral flow was studied in 42 normal patients (aged 19-68 years). Starting at the mitral annulus level (ANL) in an apical four-chamber view, the sample volume was moved downstream at 1-cm intervals. At all positions, peak early (E) and later atrial mediated (A) diastolic velocity were measured, and the distance from the transducer to the level with the highest E wave (HEL) and highest A wave (HAL) determined. The A/E ratio and time velocity integral (TVI) at ANL, HAL, and HEL were also calculated. Peak E velocity at HEL was 33% higher than at ANL (p less than 0.01) and peak A velocity was 15% higher at HAL than at ANL (p less than 0.01). The A/E ratio was minimal at HEL and maximal at ANL (0.68 +/- 0.28 vs 0.85 +/- 0.32, p less than 0.01), whereas TVI was highest at HEL and lowest at ANL. Thus, inflow parameters vary along the inflow axis. This is of importance for cardiac output measurement. The A/E ratio was more dependent on age than on sample volume position.

Adult↗
PubMed1988

Long-term follow-up of idiopathic mitral valve prolapse in 300 patients: a prospective study.

A prospective long-term follow-up study was made of 300 patients with idiopathic mitral valve prolapse, diagnosed by clinical, cineangiographic and echocardiographic criteria. There were 136 male and 164 female patients, ranging in age from 10 to 87 years (mean 42.2). The study included all patients with primary mitral valve prolapse, irrespective of clinical condition at the onset, and excluded only those patients with "secondary" mitral valve prolapse attributable to an accompanying established disorder. The average follow-up period was 6.1 years (range 6 months to 20 years). Two patients died of a noncardiac cause. The clinical condition of 153 patients remained stable. In 27 patients a supraventricular tachycardia occurred that was readily controlled with medication and caused no serious clinical complications. In 20 patients signs of mitral regurgitation appeared, but the patients remained clinically asymptomatic. Serious complications developed in 100 patients. Sudden death, most likely due to ventricular fibrillation, occurred in three patients; documented ventricular fibrillation was seen in two. Ventricular tachycardia developed in 56 patients, but in all instances the rhythm disorder was managed effectively and durably with medication. Infective endocarditis occurred in 18 patients, 4 of whom died during treatment and 6 of whom needed mitral valve replacement. The remaining eight patients suffer from severe mitral regurgitation that will require surgery in the near future. Twenty-eight patients underwent mitral valve operation because of progressive regurgitation. Cerebrovascular accidents occurred in 11 patients, but lifelong treatment with coumarin derivatives or antiplatelet aggregation agents was not considered necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Randomized double-blind study comparing tissue-type plasminogen activator with placebo in acute myocardial infarct].

In a double-blind randomised trial 129 patients with first myocardial infarction of less than 6 h duration were allocated to treatment with human recombinant tissue-type plasminogen activator (rt-PA) given intravenously over 90 min, or to placebo infusion. Coronary angiography at the end of this infusion showed that the infarct-related vessel was patent in 61% of 62 assessable coronary angiograms in the rt-PA-treated group compared with 21% in the control group. Treatment with rt-PA was not accompanied by any major complications. In the rt-PA group the circulating fibrinogen level at the end of the catheterisation was 52 +/- 29% (mean +/- SD) of the starting value.

Adult↗
PubMed1987

Accuracy of auscultatory blood pressure measurement with a long cuff.

Intra-arterial blood pressure was compared with simultaneous auscultatory measurements in 37 subjects with a wide range of blood pressures and arm circumferences; six cuffs of various lengths and widths were used. Nineteen subjects had an arm circumference of 34 cm or more (mean 40 cm) and the other 18 were considered to be non-obese and had a mean arm circumference of 30 cm. With each larger cuff, in terms of bladder surface area, auscultatory blood pressure decreased a few mm relative to intra-arterial pressure both for systolic and for diastolic measurements. Apart from diastolic pressure measured with the two 12 cm wide cuffs (12 X 23 cm, 12 X 30 cm) in the obese group all other auscultatory measurements differed less than 5% from intra-arterial pressure, albeit with considerable variability among the subjects. The differences in error among measurements with the four largest cuffs in the obese group (13 X 30 cm, 14 X 30 cm, 14 X 38 cm, and a conical cuff) were clinically irrelevant, and there was even less to choose among all six cuffs in the non-obese subjects. These results suggest that auscultatory blood pressure may be measured with acceptable accuracy with a single long bladdered cuff both in subjects with large arms and in subjects with normal sized arms.

Adult↗