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Biomedical subjects

J Deanfield

Publications and source records attributed to J Deanfield.

At least 37 records · Page 2Linked to original sources
PubMed1991

Moderate hypothermia in the management of resistant automatic tachycardias in children.

BACKGROUND: Automatic focus tachycardias are often resistant to electrical and pharmacological treatment. Moderate systemic hypothermia (32-34 degrees C) may reduce the tachycardia rate in children with His bundle tachycardia after cardiac surgery. METHODS: The case notes of seven children with automatic focus tachycardias treated with hypothermia were reviewed. Six had His bundle tachycardia after cardiac surgery and one had ectopic atrial tachycardia; all had signs of low cardiac output. RESULTS: Hypothermia led to a reduction in heart rate in all patients (from 211 (28) (mean (SD] to 146 (5) beats/minute, p less than 0.001), with rises in systolic blood pressure (from 74 (14) mm Hg to 97 (10) mm Hg, p less than 0.01) and hourly urine output (from 0.5 (0.4) ml/kg to 4.6 (2.8) ml/kg, p less than 0.02). No direct adverse effects were noted. The arrhythmia did not resolve in three children, who died (two with His bundle tachycardia after Fontan procedures and one with ectopic atrial tachycardia); the other four regained sinus rhythm which was maintained at follow up of 3-13 (mean 9) months. CONCLUSIONS: Moderate systemic hypothermia led to slowing of the arrhythmia rate and an improvement in cardiac output in patients with resistant automatic focus tachycardias. It can be used to improve the haemodynamic condition while other measures of arrhythmia control are being pursued or until spontaneous recovery of normal rhythm.

Anti-Arrhythmia Agents↗
PubMed1991

Risk factors for arrhythmia and death after Mustard operation for simple transposition of the great arteries.

From 1965 to 1980, 249 consecutive patients underwent a Mustard procedure for simple transposition of the great arteries. Hospital mortality was 23 of 249 (9.2%); follow-up for 24 years (mean, 11.7 +/- 6.1 yr) revealed 50 of 249 (20%) late deaths, of which seven were noncardiac, six were in the hospital, and 37 were sudden (27 patients with poor hemodynamics and 10 unexplained). Actuarial survival after 1, 10, and 20 years was 85, 75, and 67%. The instantaneous risk of death decreased rapidly after surgery but showed a second peak from 8 to 15 years postoperation. When last seen 87% were in New York Heart Association (NYHA) class I; 69% had sinus rhythm, 20% nodal rhythm, 10% atrial flutter, and 1% paced. Survival in uninterrupted sinus rhythm after 5, 10, and 20 years was 75, 62, and 47%. Nodal rhythm detected by annual ECG occurred in 69 patients. Excluding the early experience, the risk of loss of sinus rhythm was constant in time and constant throughout the experience (2.4%/yr). Atrial flutter was observed in 36 patients. Occurrence of atrial flutter was limited to two discrete surgical periods: the first operations (26 with atrial flutter of the first 50) and an ill-defined period in the middle of the experience. Patients not operated on during these two periods were very unlikely to develop atrial flutter (one of 104, p less than 0.001). As for death, the hazard function showed a bimodal curve, the second peak appearing earlier from 5 to 11 years. If nodal rhythm was noted on the yearly routine ECG, the risk for developing subsequent atrial flutter increased by a factor of 2.1 (p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1988

Left-ventricular cavity dimensions in children with normal and dilated hearts.

Studies were carried out to find how left-ventricular length and length/diameter ratio relate to body size and degree of dilation. By use of M-mode and two-dimensional echocardiography, diastolic cavity long axis (Led), diastolic cavity diameter (Ded), systolic cavity long axis (Les), systolic cavity diameter (Des), fractional L shortening (SFL), and fractional D shortening (SFD) were measured in children, adolescents, and young adults between two and 23 years of age, with body-surface area (BSA) between 0.5 and 2.1 m2 and with a variety of volume loads and SFD values. In normal subjects, Led/Ded was about 1.9. Regardless of age and pathology (in this age range), Led correlated consistently with BSA (Led = 3.9 + 3.2 BSA), indicating that the long axis changes rather little with pathological dilation. A plot of Led/Ded vs BSA/D2ed (in m2/cm2) formed a straight-line relation: Led/Ded = 0.77 + 16.4 BSA/D2ed. Similar relations were found for end-systolic dimensions. End-systolic L/D ratio exceeded end-diastolic L/D ratio to a degree that depended on both end-diastolic L/D ratio and SFD:Les/Des = Led/Ded + (0.22 + 2.67 Led/Ded)(SFD)2. Relations like these may be useful in the interpretation of echocardiographic images. The results suggest that left-ventricular L/D ratio may be influenced by myocardial anisotropy (dominance of hoop over meridional fiber orientation tending to promote prolate shape especially during systole) and external factors that antagonize extension of the long axis.

Adolescent↗
PubMed1988

Arrhythmia and late mortality after Mustard and Senning operation for transposition of the great arteries. An eight-year prospective study.

Arrhythmia and late sudden death are recognized complications of intraatrial repair of transposition of the great arteries. We performed a prospective study over 8 years in 100 consecutive hospital survivors who underwent Mustard (46 patients) or Senning (54 patients) operations between 1978 and 1982. Arrhythmia was analyzed by preoperative, postoperative, and serial follow-up Holter monitoring and standard electrocardiograms and was related to clinical outcome. Before repair, all patients were in sinus rhythm with a low incidence of arrhythmia. After repair, there was a gradual decrease in stable sinus rhythm during follow-up so that at a mean of 7 years after operation only 56% of patients having the Senning operation and 66% having the Mustard, with simple transposition, were in stable sinus rhythm on Holter monitoring. There was no significant difference between the two operations. Eleven patients (five after Senning [two simple, three complex], six after Mustard [five simple, one complex]) died during follow-up, four suddenly (two after Senning, two after Mustard). However, loss of sinus rhythm or the presence of arrhythmia on standard electrocardiograms or Holter recordings did not identify patients at risk for increased morbidity or mortality. Thus, even with current surgical techniques, gradual loss of sinus rhythm occurred after both Mustard and Senning operations. Because late death could not be predicted by electrocardiographic analysis, an alternative approach involving detailed hemodynamic and electrophysiologic measurements may be required to identify high-risk patients.

Arrhythmias, Cardiac↗
PubMed1987

Percutaneous balloon dilatation of aortic valve stenosis in neonates and infants.

Percutaneous balloon dilatation of severe aortic valve stenosis was attempted in thirteen patients (seven neonates and six infants). In two the valve could not be crossed and both died during subsequent operation. Two patients died during manipulation of the balloon catheter. No significant benefit was obtained in another patient who later died during operation. Balloon dilatation was successful in the remaining eight patients, reducing the aortic valve pressure gradient from a mean of 63 mmHg (95% confidence interval 38 to 88 mmHg) to a mean of 23 mmHg (95% confidence interval 7 to 39 mmHg). Two of these patients subsequently died from heart failure related to other cardiac lesions. The six survivors have done well. At follow up the maximum Doppler velocities in the ascending aorta ranged from 1.9 to 4.0 m/s after 2-23 months, but despite this evidence of an increasing valve gradient there has been lasting clinical improvement.

Aortic Valve Stenosis↗
PubMed1987

Regional extravascular density of the lung in patients with acute pulmonary edema.

The regional distribution of extravascular lung density (lung tissue and interstitial or alveolar fluid per unit thoracic volume) and fractional pulmonary blood volume (volume of blood per unit thoracic volume) was measured in five patients with acute interstitial pulmonary edema and two patients with acute alveolar edema. We found a uniform increase in extravascular lung density in the patients with acute interstitial edema but a preferentially dependent distribution in the patients with alveolar edema. Fractional blood volume had an abnormally uniform distribution in patients with interstitial edema. In alveolar edema, there was marked redistribution of blood volume away from severely edematous regions. The results are in agreement with previous experimental work with animal models. The distribution of extravascular lung density and fractional blood volume in subjects with acute interstitial edema is, however, different from that found in subjects with chronic interstitial edema, suggesting that the pathophysiological characteristics of the two conditions may be different.

Acute Disease↗
PubMed1985

Activity of transient myocardial ischemia out of hospital in coronary artery disease and implications for management.

The management of patients with angina pectoris is based largely on the severity of symptoms, coronary anatomy and left ventricular function. The outcome for these patients is highly variable and depends largely on the degree of ischemic damage to the left ventricular myocardium. Recent work suggests that exercise-induced myocardial ischemia with or without angina is associated with a poor prognosis. Ambulatory monitoring of the electrocardiogram has revealed that most patients have frequent and prolonged episodes of transient ischemia out of hospital. These episodes are often asymptomatic and associated with ordinary everyday activities. In addition, ambulatory monitoring has demonstrated that transient ischemia during daily life has a circadian variation with exacerbations and peak density of ischemia in the first 4 to 6 waking hours of the day. Further studies have demonstrated that regional decreases in coronary blood flow occur during these ischemic episodes and have the same features seen out of hospital on continuous monitoring. These newly noted characteristics of transient ischemia raise a number of practical questions for treatment. Is it necessary to relieve all ischemic activity quite apart from that which occurs with chest pain? Does present use of antianginal medication neglect the early morning increases in transient ischemia that occur, and are different dosage regimens required to treat ischemia adequately? Does suppression of all ischemic activity further protect myocardium and improve prognosis for the patient?

Angina Pectoris↗
PubMed1985

Effects of verapamil in preventing early postinfarction angina and reinfarction.

Because verapamil is effective in the treatment of "preinfarction" angina, a single-blind, placebo-controlled trial was performed in 17 patients admitted to the coronary care unit with transmural acute myocardial infarction (AMI) to assess the effects of verapamil on angina and reinfarction after AMI. The study was terminated because results obtained in the initial 17 patients indicated that verapamil is not as effective in treating angina after AMI as it is in angina before AMI and does not prevent reinfarction. Continuous electrocardiographic monitoring during the first 3 days after AMI showed the presence of transient episodes of ST-segment elevation in 4 patients taking verapamil and 4 patients taking placebo. The total number and duration of transient ischemic episodes was similar in the 2 groups (46 vs 41 and 23 +/- 22 vs 17 +/- 15 minutes, respectively). The percentage of transient ischemic episodes accompanied by chest pain was similar in both groups (10%). The ischemic episodes were never preceded by important increases of heart rate. Four patients taking verapamil and 4 taking placebo had reinfarction within the first 10 days after the incident AMI. These findings suggest that the prevailing mechanisms of myocardial ischemia in the immediate post-AMI period could be different from those operating in angina before AMI.

Aged↗
PubMed1985

Local abnormalities of right ventricular depolarization after repair of tetralogy of Fallot: a basis for ventricular arrhythmia.

Ventricular arrhythmia is common after repair of tetralogy of Fallot (TF) and may cause sudden death. To explore the mechanisms, ambulatory electrocardiographic monitoring and electrophysiologic studies were undertaken, without the use of provocative tests, in 22 patients 5 to 24 years (mean 13) after repair. His-Purkinje and right ventricular (RV) apical activation times were measured to assess conduction. Endocardial mapping of the right ventricle was performed, with additional recordings from the left ventricle in 10 patients, to detect abnormalities of local depolarization and repolarization. Local RV electrograms were fractionated or delayed in 12 patients (55%) at 1 or more RV sites (septum in 7 patients, outflow in 7, free wall in 2 and apex 1 patient), reflecting disordered depolarization, but left ventricular recordings were normal in all. Ventricular arrhythmia out of hospital was more common (p less than 0.05) and more severe (p less than 0.01) in the patients with depolarization abnormalities than in those with normal electrographic findings. In contrast, there was no association between ventricular arrhythmia and conduction disturbances. Abnormalities of RV repolarization, consisting of low-frequency signals after the T wave, were observed in 17 patients (77%), but were not associated with arrhythmia. Thus, ventricular arrhythmia during daily life was associated with fractionated depolarization at multiple sites in the right ventricle. This suggests that there are widespread areas of RV myocardial damage that provide substrates for ventricular tachycardia.

Adolescent↗
PubMed1985

Decision making in the definitive repair of the heart with a small right ventricle.

Data from 51 patients with small right ventricle who underwent a definitive repair were analyzed retrospectively. The repair was considered complete (29 patients) when it resulted in relief of the right ventricular outflow tract obstruction by closure of intracardiac (atrial septal defect) and extracardiac (when present) shunts. The repair was considered a definitive palliation when the intracardiac and the extracardiac shunts were left open (11 patients). A complete separation of the systemic and pulmonary circulations was established with the use of the Fontan procedure in another 11 patients. The outcome in these patients correlated with the preoperative size of the right ventricular cavity as assessed by measurement of the tricuspid valve diameter and by consideration of the right ventricular morphology (based on the tripartite right ventricular concept). If the tricuspid valve of a tripartite right ventricle has a diameter above the lower 99% confidence limit of the normal mean it can be safely incorporated in a complete repair (p less than .01). This also applies for a right ventricle without a trabecular portion, provided the criteria of the Fontan operation are fulfilled. Right ventricles with tricuspid valve diameters smaller than the lower 99% confidence limit of the normal mean cannot sustain total pulmonary blood flow. Definitive palliation should be reserved for use in patients whose right ventricles are too small for complete repair and who are not suitable candidates for Fontan's procedure.

Adolescent↗
PubMed1984

Role of heart rate in pathophysiology of chronic stable angina.

11 patients with chronic, stable, effort angina, off medication apart from glyceryl trinitrate, were monitored continuously by electrocardiogram (ECG) during normal, unrestricted daily activity. Computerised ECG analysis demonstrated during 33 twenty-four hour periods of monitoring, 278 episodes of transient ischaemic ST segment depression of which 52 were associated with angina. In the 15 minutes preceding the onset of ischaemia, heart rate did not increase in 164 episodes, increased slightly (greater than or equal to 5 beats/min) in 61, and increased moderately or markedly (greater than or equal to 10 beats/min) in 53. Findings were similar when episodes with or without angina or episodes of different severity were analysed separately. In all patients, periods of sinus tachycardia exceeding the control rate by more than 30 beats/min and lasting more than 10 minutes, often occurred in the absence of angina and/or ST segment depression. Also, in 65% of the ischaemic episodes, heart rate at the beginning of the ST change was either below or less than 10 beats/min above the modal value of the twenty-four hour heart rate. This suggests that increased myocardial demand is not necessarily the only or the most common cause of acute ischaemia in patients with chronic effort angina during unrestricted daily activity. Factors which only transiently interfere with myocardial oxygen supply are probably important in this syndrome.

Aged↗
PubMed1984

Cigarette smoking and the treatment of angina with propranolol, atenolol, and nifedipine.

To determine whether cigarette smoking affects the results of drug treatment for angina, we studied 10 cigarette smokers with angina who were given placebo, nifedipine (60 mg per day), propranolol (240 mg per day), and atenolol (100 mg per day), each for one week. The four-week double-blind study was repeated with the same randomly determined order of drug sequences, after all 10 subjects had stopped smoking. Before and after the subjects stopped smoking, all three drugs significantly reduced the frequency of angina, as measured with angina diaries, and improved the results of maximal exercise testing and 48-hour ambulatory monitoring of ST segments (P less than 0.01). However, during the nonsmoking phase of the study, there was an overall decline in the frequency of angina and an improvement in performance on exercise testing (P less than 0.05) as compared with the smoking period, although the results of 48-hour ambulatory monitoring remained unchanged. The improvement after patients stopped smoking was greater during treatment with nifedipine than during administration of the other two drugs or placebo. Blood levels of propranolol were increased when patients stopped smoking; levels of nifedipine and atenolol were unchanged. Our data show that smoking had direct and adverse effects on the heart and interfered with the efficacy of all three anti-anginal drugs, but with nifedipine the most.

Angina Pectoris↗
PubMed1984

The interaction of cigarette smoking and beta-adrenoceptor blockade.

The importance of the interaction between smoking and propranolol (metabolised in the liver) and atenolol (excreted almost entirely in the urine) was investigated in a double-blind placebo-controlled trial. Resting and exercise heart rates were significantly greater during smoking than no-smoking phases. Atenolol and propranolol significantly improved ST segment response after exercise whether or not the patients were smoking. Plasma propranolol significantly increased when patients stopped smoking whereas there was no such change in atenolol levels.

Adrenergic beta-Antagonists↗
PubMed1983

Treatment of angina pectoris with nifedipine: importance of dose titration.

The effects of different doses of nifedipine on frequency of angina and objective measurements of myocardial ischaemia during exercise were studied in 10 patients with stable angina pectoris. In a single blind trial over nine weeks patients received one week's treatment each with placebo, nifedipine 10 mg, 20 mg, 30 mg, 40 mg, 30 mg, 20 mg, 10 mg, then placebo three times a day. The response to the different doses of nifedipine was highly variable. On exercising, three patients achieved a consistent improvement in workload attained before onset of ST segment depression and maximum ST depression during exercise testing during all active phases. Four patients improved with 10 mg three times a day but deteriorated at higher doses. In two patients there was no objective or subjective improvement with any dose of the drug, while in one patient anginal frequency increased and there was objective deterioration during exercise testing at doses above 10 mg three times a day. Thus a dose of nifedipine that is beneficial in one patient may have minimal or opposite effects in another. These results indicate the importance of careful titration of doses for individual patients if the maximum benefit from nifedipine is to be obtained in patients with exertional angina.

Adult↗
PubMed1983

Computed tomography of the heart: initial experience.

Computed tomography (CT) provides non-invasive diagnosis of cardiac lesions by direct demonstration of the myocardium and the individual cavities of the heart. The potential role of CT scanning in the detection and quantitation of acute myocardial infarction has been previously investigated in experimental animals. Initial experience in assessing 10 patients admitted with recent infarction on biochemical and electrocardiographic evidence is reported. Intravenous infusion of iodinated contrast agents produced contrast enhancement either of the rim or diffusely through the myocardium in the area of infarct, as sited electrocardiographically. Patients with coronary artery bypass grafts and hypertrophic cardiomyopathy have also been studied by this method. Cardiac CT with intravenous administration of contrast may have an important role in the future in assessment and follow-up of ischaemic heart disease.

Cardiomyopathy, Hypertrophic↗
PubMed1983

Nuclear magnetic resonance imaging of the heart. Current status and future prospects.

The basic principles and current status of proton nuclear magnetic resonance imaging are outlined. Nuclear magnetic resonance images of the heart have improved in quality with advances in technique and better gating but clinical experience remains very limited. Myocardial infarction has been shown in animals and man, and plaques of atheroma have been seen with nuclear magnetic resonance flow studies. Further improvements in image quality, faster examination times, 23Na imaging, and the use of paramagnetic contrast agents are advances that are anticipated in the near future.

Animals↗