Biomedical subjects
Publications and source records attributed to J M Morgan.
Coronary arterial occlusion may occur experimentally during acute myocarditis but has not been documented in man. We report the case of a young female with severe myocarditis who later required cardiac transplantation and in whom coronary occlusion was demonstrated arteriographically before transplantation and by pathological examination of the heart after explantation.
We have reviewed the 25 patients who, between 1973 and 1988, presented to the Brompton Hospital in adulthood with persistence of the arterial duct (ductus arteriosus). As pulmonary arteriolar resistance is the main determinant of management and prognosis in this condition, the patients were divided into groups with either normal or mild elevation of resistance (less than 10 units/m2: 19 patients) or with severe elevation (greater than 10 units/m2: 6 patients). Patients with normal pressures or mild elevation tended to be older (mean age 45 years). Many (70%) were asymptomatic, but dyspnoea with signs of left heart failure was the commonest presenting complaint. Surgical closure of the duct was performed in 16 with good result in all. Survival for the entire group, however, was long. There was a symptomatic indication for surgery (due to hyperdynamic circulation) in 5. In those with severely elevated pulmonary arteriolar resistance, the mean age of presentation was 31 years and the survival short. The commonest presenting symptom was dyspnoea. Surgical closure of the duct was attempted in two patients but with a poor outcome in both. All patients with an elevated resistance had developed this complication by the third decade of life. Significant elevation was not a feature of older patients, suggesting that, in this age group, the risk of elevation is slight. Surgery, nonetheless, may be indicated for relief of symptoms due to a large systemic to pulmonary shunt.
Sophisticated pacemakers now afford greater benefit than only relief of syncope for patients with symptomatic bradyarrhythmia. For clinical reasons it is inappropriate to implant ventricular demand (VVI) pacemakers in every patient, but for both clinical and economic reasons it is also undesirable to use dual-lead or rate-responsive systems indiscriminately. However, the published guidelines for pacemaker choice and investigation are inadequate. We have analysed the clinical assessment and the investigations required in a series of 150 patients with various electrophysiological disorders, considered consecutively for pacemaker implantation using an algorithm to assist decisions. Holter electrocardiography in 77.3%, exercise testing--formal (in 9.3%) or informal (during Holter electrocardiography), electrophysiology study (EPS)--full in 15.3% and partial in 29.3%, and trial of pacing (10.7%) were all used to characterize dysfunction and to define appropriate pacing mode. 142 patients were paced--57.0% with single lead modes (12.7%) AAI, 44.3% VVI) and 43.0% dual-lead (2.8% DVI, 23.9% VDD or VAT, 16.2% DDD). Three patients received rate-responsive systems (VVIR) which, if available, would have been used in nine; four would have been suitable for AAIR and four for dual-lead responsive pacing (DVIR, DDIR or DDDR). We offer a rational approach based on published data for investigation and pacemaker choice in the management of patients with bradyarrhythmia.
Adaptation of effective refractory period (ERP) and monophasic action potential (MAP) shortening after a step increase in drive frequency was determined at adjacent endocardial sites in the right ventricle of six patients without myocardial disease. ERP and MAP shortening occurred simultaneously. ERP shortening and MAP shortening were similar in time course in individuals, although the degree of shortening varied between individuals as the size of the step increase in pacing frequency varied. Shortening of both ERP and MAP was complete after a mean of 67 +/- 7.5 seconds. To allow group analysis, the percent change from baseline of action potential duration and ERP was calculated for each patient at intervals during adaptation and mean percent change for the group plotted against time from the beginning of the step rate increase. A mean step increase in pacing frequency of 49.3% of baseline for the group caused the ERP to shorten by a mean of 18.12%, and MAP90 by 17.43% of baseline. There was no significant difference (P = 0.05) between the action potential and ERP adaptation curves of the group. We conclude that in normal myocardium, there is a close relationship between shortening of ventricular ERP and action potential duration after a change in rate.
Before the introduction of computed tomographic (CT) scanning, aortography was the investigation of choice for acute aortic dissection. Between 1978 and 1982, 24 patients were referred to the Brompton Hospital with suspected acute thoracic aortic dissection; all had aortography with diagnosis confirmed at surgery (n = 12) or necropsy (n = 2) or supported by clinical outcome (n = 8). One patient in whom aortography was negative had type B dissection at necropsy and another patient was lost to follow up. CT scanning became available in this unit in 1983 and between 1983 and 1987 was used as the only imaging investigation in 32 patients with suspected acute dissection of the thoracic aorta while in a further 22 patients aortography was used alone. Results were confirmed at surgery (n = 18), necropsy (n = 3), or supported by clinical outcome (n = 31). Two patients were lost to follow up. In an additional 16 patients both aortography and CT scanning were performed with concordant findings in 10. In six in whom the results were discordant, aortography was normal in three in whom subsequent CT scanning showed type B dissection and CT scanning was normal in three patients in whom aortography showed type A dissection. Both CT scanning and aortography are reliable techniques for assessment of suspected acute dissection of the thoracic aorta. Both techniques misdiagnose occasionally and the frequency of misdiagnosis will be minimised by performing both investigations in patients where the level of clinical suspicion is high and the initial investigation negative. CT scanning tends to miss type A dissection and in view of the success of surgery in this condition this failing has the more serious clinical consequences.
During 1970-87 43 patients with unexplained pulmonary hypertension (mean pulmonary arterial pressure greater than 25 mm Hg) were admitted to the Brompton Hospital and classified by angiographic criteria as having either symmetrical peripheral pulmonary artery pruning (thought to represent primary plexogenic pulmonary arteriopathy), n = 21, or asymmetrical pulmonary arterial occlusions (thought to represent chronic thromboembolic disease), n = 22. Patients with symmetrical pulmonary arteriopathy had significantly higher mean pulmonary arterial pressures (67 mm Hg) at the time of presentation than those with asymmetrical pulmonary arteriopathy (49 mm Hg). Clinical distinction between these two groups was impossible. Survival from the time of diagnosis was similarly poor in the two groups (26 weeks and 38 weeks) and did not correlate with any of the haemodynamic measurements. The difficulties in making distinctions between these conditions are discussed.
If retrograde arterial catheterization of the left ventricle fails because of a stenosed native or tissue valve or is contraindicated because of the presence of a mechanical aortic prosthesis, then alternative routes of access to the left ventricle are either transseptal or direct (transapical) left ventricular puncture. The transseptal approach is contraindicated in the presence of a mechanical mitral valve prosthesis. Under these circumstances we have used direct transapical left ventricular puncture in the treatment of 112 patients and have found this technique to be successful with little associated risk. A major complication occurred in 3% of the patients, but the study provided the required data in 95%, and these figures compare favorably with the reported results of transseptal catheterization.
Financial and other constraints, such as operative risk, may prevent older patients being considered for coronary arterial bypass grafting. Grafting was performed in 315 elderly patients (244 males, 71 females, age 65-79, mean 69 years) between 1981-1986. All patients had limiting angina, 38% had rest pain, 90% were housebound and 80% had triple-vessel disease. Impairment of left ventricular function was absent in 46%, mild in 20%, moderate in 23% and severe in 10% of patients. Grafts (saphenous vein or internal mammary artery) were inserted into 3 vessels (52%), 4 vessels (42%), 5 vessels (6%), 6 vessels (0.5%). Death during surgery occurred in 1.6% and a further 3.5% of patients died later during the same admission (70% of deaths were among the 33% with preoperative moderate or severe left ventricular impairment). Surgical complications included myocardial infarction (8%), cerebrovascular accident (1%), transient cerebral vascular ischaemia (5%), chest infection (10%) and wound infection (4%). Median stay on the intensive care unit was 1 day and median total hospital stay 12 days. 299 patients therefore survived to leave hospital and follow-up data are available for 217 (72%) of these. 96% were subjectively improved by surgery, 88% being free of angina on no antianginal drugs a median of 72 weeks (range 8-307) and a further 8% not limited by angina on medical therapy a median of 85 weeks (range 9-302) after surgery. We conclude that coronary arterial surgery is an effective treatment for angina in the elderly. This will have consequences for future resource allocation if the elderly are not to be denied effective therapy because of financial rather than clinical restraints.
A case of Noonan's syndrome with aneurysmal dilatation of the sinuses of Valsalva is described. Enlargement of the left heart border on the postero-anterior chest radiograph was initially interpreted as dilatation of main pulmonary artery but aortography confirmed the presence of large aneurysms of two of the sinuses of Valsalva. Connective tissue abnormalities, known to occur in Noonan's syndrome, could be responsible for aortic abnormalities in this syndrome.
It is difficult to distinguish between restrictive cardiomyopathy and constrictive pericarditis on the basis of clinical findings and simple investigation. Cardiac catheterisation has been the reference standard for diagnosis but even this does not always permit an accurate distinction. A Summagraphics digitiser and Prime 750 computer system were used to digitise the echocardiograms of 15 patients with restrictive cardiomyopathy, 10 with constrictive pericarditis and a group of 20 age and sex matched normal subjects of similar age and sex distribution. Compared with controls, patients with restrictive cardiomyopathy showed a significant reduction in the following variables (a) decreased fractional shortening, (b) decreased peak left ventricular filling and emptying rates, (c) decreased percentage posterior wall thickening, and (d) decreased peak left ventricular posterior wall thickening and thinning rates. Whereas patients with constrictive pericarditis only had significantly reduced peak left ventricular filling and posterior wall thinning rates and significantly increased posterior wall thinning rate. When patients with restrictive cardiomyopathy were compared with those with constrictive pericarditis the significant differences were: (a) decreased peak left ventricular emptying rate, (b) decreased percentage posterior wall thickening, and (c) decreased peak left ventricular posterior wall thickening and thinning rates. Digitisation of M mode echocardiograms, with particular attention to posterior wall function, may be a useful adjunct to cardiac catheterisation in distinguishing restrictive cardiomyopathy from constrictive pericarditis.
To define the range of cardiac involvement in the Churg-Strauss syndrome, M mode, continuous wave Doppler, and cross sectional echocardiograms were recorded in twelve patients with the disorder. The M mode recordings were digitised and the cross sectional images were recorded with standardised gain settings to determine regional myocardial echo amplitude. Left ventricular end diastolic and end systolic dimensions were increased above the normal 95% confidence interval in four patients, three of whom showed a depressed shortening fraction. Mitral regurgitation was present in six patients; this was severe enough to need valve replacement in two. Mean echo amplitude in both the septum and the posterior wall was significantly increased above normal by a mean (SD) of 4.87 (2.57) dB, suggesting the presence of myocardial fibrosis. There was no evidence of subendocardial involvement as there is in other hypereosinophilic syndromes. Mitral regurgitation is common in the Churg-Strauss syndrome. This cannot be ascribed to involvement of the cusps or chordae and it occurs even when ventricular function is well preserved. It is suggested that mitral regurgitation is caused by diffuse myocardial fibrosis.
Pumped continuous arteriovenous haemofiltration offers a means of managing oliguric renal failure. We report our experience with the use of this technique in the management of patients with oliguric renal failure complicating cardiothoracic surgery, and conclude that it allows management of this complication without transfer to a renal unit.
Between 1964 and 1986 a total of 71 pulmonary embolectomies were performed for acute massive pulmonary embolism. All patients were severely compromised haemodynamically. Sixteen (64%) of 25 patients who had sustained significant periods of cardiac arrest before operation died. The principal cause of death in this group was severe neurological damage. Five (11%) of the 46 who had not had a cardiac arrest died. The 50 (70%) patients who survived did so largely without morbidity during their hospital admission and in the follow up period. Most were not treated with long term anticoagulants and only two had another embolism. When a patient with acute massive pulmonary embolism is too ill to be given thrombolytic treatment, or when thrombolysis is either contraindicated or too slow in producing benefit, pulmonary embolectomy remains an effective alternative treatment with an acceptable mortality.
We present a method for immunohistochemical demonstration of surface-associated thyroid-stimulating hormone (TSH) receptors on direct imprints of rat thyroid follicular cells at the light microscopic level, by use of dinitrophenyl (DNP)-labeled bovine TSH as the primary probe in a DNP-hapten sandwich staining (DHSS) procedure. The light microscopically invisible diaminobenzidine (DAB) product of the enzyme reaction was amplified with a DAB enhancement technique (silver amplification), which yielded a reliable and distinct light microscopically visible cell surface staining. The consistently negative control results after inhibition with TSH receptor-specific reagents provide evidence in support of immunohistochemical localization of surface membrane-associated TSH receptors.
A young man with Takayasu's disease had severe right and left coronary ostial stenoses. Severe angina was relieved by operation at which the right coronary ostium was enlarged by a pericardial patch extending across the stenosis from aorta to coronary artery; the aortic end of a vein graft to the left coronary artery was attached to this patch. This technique may reduce the risk of recurrence of ostial stenosis or of stenosis at graft origins.
The use of conventional open-port catheters in total artificial heart (TAH) research shortens the survival time of recipients owing to sepsis and embolism caused from the catheters. Valuable data are lost when an open-port catheter clots off, and transducer position must be keyed to the level of the atria for accuracy. The need for an accurate, easily obtainable, noninvasive method for measuring atrial pressure is of obvious value. Such a method has been developed in vitro using a device that measures the stroke volume of a pneumatic ventricle. The stroke volume is obtained by quantifying the amount of air exiting a pneumatic TAH in diastole. Using this information ventricular filling rates can be calculated by the stroke volume measurement device, and these rates are correlated to measured atrial pressures. There is no need to continually adjust transducer levels in relation to the atria with this system. The data show an average percentage error of 2.4 of full scale (25 mm Hg) or 0.6 mm Hg. The method of measurement is accurate, without limitations on driving parameters. The information is available without any additional prosthetic fabrication or surgical intervention than that already needed for basic TAH implantation. This method of measuring atrial pressures now needs to be proved effective in vivo.
Explore the source record for details and available documents.
The event-related potential (ERP), produced by subjects who were experiencing a gradually increasing heat stimulus, was recorded 3.5 sec before and 1 sec after a motor response. Subjects responded when the stimulus was 'just warm,' 'just at prickling pain' or 'above the temperature of just prickling pain.' Two control procedures mimicked the readiness potential (RP) and motor potential (MP) experiments. The results showed that the steadily rising negative MP was modified to a positive wave before the decision of 'warm.' During the 'pain' and 'above pain' conditions, the pre-decision slow wave was less negative than the MP but less positive than that of the 'warm' condition. A temperature control condition confirmed that rising temperature alone did not produce these results. Principal components analysis confirmed these differences by producing factors which were interpreted as representing the ERPs of the conditions of 'warm,' 'pain,' 'above pain,' RP and MP. It was evident from pilot studies that uncontrolled electrical activity from the skin potential response (SPR) was contaminating the results. SPR forced all ERP curves in the positive direction and several attempts to eliminate the SPR from the ERP data failed. While the SPR was produced differentially across conditions and across the experimental session, the smaller the variability in the electro-oculogram (EOG) recorded from above and below the orbits, the smaller was the SPR contamination that we recorded in the ERP. Therefore, we selected subjects for this experiment who showed a stable orbital EOG.