Dobutamine thallium myocardial perfusion tomography.

Dobutamine has favorable properties for the pharmacologic manipulation of myocardial oxygen demand in the provocation of ischemia during the investigation of coronary artery disease. The value of dobutamine infusion for thallium myocardial perfusion tomography was assessed in 50 patients with exertional chest pain undergoing coronary arteriography. Dobutamine was infused in 5-min stages at incremental rates from 5 to 20 micrograms/kg per min or until limited by symptoms. The myocardium was divided into nine segments for analysis of perfusion. Thirty-nine of 40 patients with coronary artery disease had a reversible perfusion defect demonstrated by dobutamine thallium tomography (sensitivity 97%) and 8 of 10 patients with normal coronary arteries had normal myocardial perfusion (specificity 80%). These values were significantly better than the sensitivity and specificity of exercise electrocardiography (78% and 44%, respectively; p less than 0.01). There was a significant relation between the mean number of segments with abnormal perfusion and the number of diseased coronary vessels (0.6, 2.6, 4.4 and 6 segments in zero-, one-, two- and three-vessel disease, respectively; p less than 0.001). There was also a significant relation between the maximal tolerated dose of dobutamine and the treadmill exercise time (r = 0.56, p less than 0.001), but a wide range of exercise times was achieved in the 15- and 20-micrograms/kg per min groups, principally because of exercise limitation by noncardiac symptoms. Dobutamine infusion was well tolerated in all patients, including six with asthma. There were no significant arrhythmias or limiting symptoms other than chest pain.(ABSTRACT TRUNCATED AT 250 WORDS)

Simultaneous endocardial and epicardial monophasic action potential recordings during brief periods of coronary artery ligation in the dog: influence of adrenaline, beta blockade and alpha blockade.

Local differences in the time course of recovery of excitability during the early phase of myocardial ischaemia are important in the genesis of arrhythmias. Catecholamines are known to encourage the formation of arrhythmias and adrenergic blockade is a recognised therapeutic regime. The purpose of this study was to compare the effect of short periods of coronary artery ligation on endocardial and epicardial repolarisation time, to assess any disparity between the two surfaces, and investigate the influence of catecholamines and adrenergic blockade. Simultaneous left ventricular endocardial and epicardial monophasic action potentials (MAPs) were recorded during short periods of left anterior descending coronary artery (LAD) ligation in 9 open chested dogs. Recordings were made during two 90 s periods of LAD ligation. Two further ligations were made during infusion of adrenaline (1 microgram.kg-1.min-1). Subsequently ligations were made after beta blockade with propranolol (0.25 mg.kg-1) and then in the presence of a combination of alpha blockade (phentolamine, 0.15 mg.kg-1) and beta blockade. MAP duration was measured at 90% repolarisation. LAD ligation produced a marked shortening of MAP duration epicardially with only minimal shortening endocardially, which resulted in a highly significant difference between the repolarisation times on the two surfaces. The disparity between surfaces tended to be augmented by adrenaline and was significantly minimised by either beta blockade alone or in combination with alpha blockade. Our results show rapid development of substantial regional differences in repolarisation time between endocardium and epicardium in response to "ischaemia".(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical features, microbiology and surgical outcomes of infective endocarditis: a 13-year study from a UK tertiary cardiothoracic referral centre.

BACKGROUND: Infective endocarditis (IE) causes substantial morbidity and mortality. Patient and pathogen profiles, as well as microbiological and operative strategies, continue to evolve. The impact of these changes requires evaluation to inform optimum management and identify individuals at high risk of early mortality. AIM: Identification of clinical and microbiological features, and surgical outcomes, among patients presenting to a UK tertiary cardiothoracic centre for surgical management of IE between 1998 and 2010. DESIGN: Retrospective observational cohort study. METHODS: Clinical, biochemical, microbiological and echocardiographic data were identified from clinical records. Principal outcomes were all-cause 28-day mortality and duration of post-operative admission. RESULTS: Patients (n = 336) were predominantly male (75.0%); median age 52 years (IQR = 41-67). Most cases involved the aortic (56.0%) or mitral (53.9%) valves. Microbiological diagnoses, obtained in 288 (85.7%) patients, included streptococci (45.2%); staphylococci (34.5%); Haemophilus, Actinobacillus, Cardiobacterium, Eikenella, Kingella (HACEK) organisms (3.0%); and fungi (1.8%); 11.3% had polymicrobial infection. Valve replacement in 308 (91.7%) patients included mechanical prostheses (69.8%), xenografts (24.0%) and homografts (6.2%). Early mortality was 12.2%, but fell progressively during the study (P = 0.02), as did median duration of post-operative admission (33.5 to 10.5 days; P = 0.0003). Multivariable analysis showed previous cardiothoracic surgery (OR = 3.85, P = 0.03), neutrophil count (OR = 2.27, P = 0.05), albumin (OR = 0.94, P = 0.04) and urea (OR = 2.63, P < 0.001) predicted early mortality. CONCLUSIONS: This study demonstrates reduced post-operative early mortality and duration of hospital admission for IE patients over the past 13 years. Biomarkers (previous cardiothoracic surgery, neutrophil count, albumin and urea), predictive of early post-operative mortality, require prospective evaluation to refine algorithms, further improve outcomes and reduce healthcare costs associated with IE.

Magnetic resonance imaging during dobutamine stress in coronary artery disease.

Cine magnetic resonance imaging (MRI) provides a tomographic method of assessing regional ventricular function in any desired plane. It has not been possible to obtain adequate images during dynamic exercise, and this has limited its value in patients with coronary artery disease (CAD). Therefore, an infusion of dobutamine was used to study 25 patients with exertional chest pain and abnormal exercise electrocardiograms. Areas of abnormal wall motion were compared with areas of abnormal myocardial perfusion imaged by dobutamine thallium emission tomography and with coronary arteriography. Twenty-two patients had significant CAD. Twenty-one (96%) of these patients had reversible myocardial ischemia shown by dobutamine thallium tomography, and 20 (91%) had reversible wall motion abnormalities shown by dobutamine MRI. Comparison of abnormal segments of perfusion and wall motion showed 96% agreement at rest, 90% agreement during stress, and 91% agreement for the assessment of functional reversibility. The normalized magnetic resonance signal intensity of the ischemic segments showed a small but significant reduction when compared with that of normal segments (-67 units [9.2%]; p less than 0.05). Dobutamine infusion was well-tolerated, despite causing chest discomfort in 24 patients (96%). Nine patients (36%) developed a minor dysrhythmia that was usually ventricular premature complexes, but this did not limit infusion, and other side effects were mild. The short plasma half-life of dobutamine makes it ideal as a stress agent for imaging techniques (such as MRI), and these results suggest that it is more effective in the provocation of wall motion abnormalities than is dipyridamole in patients with CAD.

Systolic and diastolic ventricular function in cardiac amyloidosis. Studies in six cases diagnosed with endomyocardial biopsy.

Five cases of cardiac amyloidosis diagnosed after endomyocardial biopsy are described. Systolic function was normal in three cases as assessed by cardiac index, ejection fraction and maximal velocity of contractile element shortening at zero developed pressure. The diastolic dip and plateau wave form was a characteristic but not an invariable finding. Increased ventricular end-diastolic pressure but normal end-diastolic volume indexes in all cases implied a disorder of diastolic compliance. The diastolic pressure-volume plots suggested a sudden decrease in distensibility after normal early filling of the ventricle. The functional defect did not necessarily differ from that of other diseases of heart muscle. Therefore, hemodynamic data should not be relied upon for diagnostic purposes. Electron microscopy was the most reliable aid in making the diagnosis from the endomyocardial biopsy specimens especially in the presence of fibrosis. It may not be valid to assume a diagnosis of cardiac amyloidosis from the finding of amyloid in other organs.

Coronary artery fistulas presenting with bacterial endocarditis.

Coronary artery fistulas are rare congenital malformations. Two cases presenting with bacterial endocarditis are described. Both were treated successfully by grafting of the coronary artery and ligation of the fistula.

Is the MIC useful in deciding to treat endocarditis surgically?

The infecting pathogen and its susceptibility to antibiotics is used to suggest prognosis in endocarditis. A case study was performed in a tertiary referral cardiology centre to assess the contribution of the measurement of minimum inhibitory concentration (MIC) to the decision to treat endocarditis surgically. The records were examined of 125 patients admitted between 1981 and 1999 in whom the minimum inhibitory concentration for the pathogen had been measured. The measures of outcome were mortality at time of hospital discharge and at 6 months, surgical referral and cure by medical treatment. Endocarditis caused by Staphylococcus aureus with a raised MIC of flucloxacillin (methicillin) was associated with higher mortality even if glycopeptides were used in treatment (< or = 35 mg/l 0/7 versus MIC 1-2 mg/l 4/13, P = 0.01). Elevated MICs of flucloxacillin in S. aureus infection or of gentamicin in streptococcal disease were associated with surgical intervention. There were no significant differences between bacterial pathogens in mortality, surgical referral or cure by medical treatment. The measurement of MIC appears prognostically important in deciding the surgical management of endocarditis.

The incidence of significant pericardial effusion and tamponade following major aortic root surgery.

OBJECTIVE: To examine the hypothesis that the incidence of significant pericardial effusion following aortic root surgery is higher than anticipated after cardiac surgery. DESIGN: A retrospective data analysis. SETTING: A tertiary referral centre for cardiothoracic surgery. SUBJECTS: All patients undergoing aortic root surgery either with or without aortic valve replacement between January 1991 and July 1993. RESULTS: Three patients developed late cardiac tamponade (7-10 days post-operatively) and a further three developed clinically significant pericardial effusions as a result of post-pericardiotomy syndrome. The 31.6% (95% confidence limit: 12.5-56%) incidence of significant pericardial effusions following aortic root surgery is therefore significantly higher than anticipated after cardiac surgery (0.8-6). CONCLUSION: These data support the hypothesis that the incidence of significant pericardial effusion following aortic root surgery is higher than anticipated after cardiac surgery. We recommend that echocardiography is routinely performed during the post-operative period in these patients to exclude significant pericardial effusions.

The National Service Framework: six years on.

Has the National Service Framework for coronary heart disease resulted in the improvements in cardiac services it promised when first published six years ago?

Sarcoidosis of the heart.

Patients who have bilateral hilar lymphadenopathy (BHL) alone need annual follow-up with chest X-ray, ECG, 24-h monitoring, exercise testing, lung function and possible thallium 201 scanning. Provided these tests are normal or negative, there is no evidence of other organ or parenchymal lung involvement and the extent of BHL is stable or regressing, then restriction to multicrew operation should be required until regression has occurred or a period of two years has elapsed. Although a patient with generalized or systemic sarcoidosis and no apparent cardiac involvement should be allowed to drive a car, certification to fly should be dependent on physical well being and restricted to multicrew operation. With our present inability to diagnose cardiac involvement in sarcoidosis with complete sensitivity, this restriction should be indefinite as cardiac involvement in sarcoidosis may only become apparent many years after the diagnosis of systemic sarcoidosis has been made. Patients with known cardiac involvement in sarcoidosis should also be refused a driving licence unless they are under regular and close supervision for possible arrhythmic complications. Permanent pacing may be needed. Patients with known cardiac sarcoid should be refused certification to fly.

Anticoagulants in cardiovascular diseases.

Anticoagulants form an important group of drugs in the management of cardiovascular diseases. These drugs are being increasingly employed but the indications and therapeutic regimens for their use remain unclear in certain situations. This review summarizes the currently accepted practice and aims to provide a balanced view of the ill-defined areas of anticoagulant therapy in cardiovascular diseases.

Choice of therapy in angina.

Ischaemic heart disease is one of the most serious health problems in the Western world. Angina is the commonest symptom and its therapy is still palliative, although complete relief from symptoms can generally be achieved by appropriate drugs or revascularization procedures. The degree of disability caused varies and therapeutic choice depends on patient characteristics and causative factors in the production of angina. This article reviews the management of angina from ischaemic heart disease assuming other causes like valvular disease, congenital anomalies, arteritis and cardiomyopathies have been excluded.

Complications of transvenous temporary pacemaker insertion.

The indications for temporary pacemaker insertion are more widely documented than the complications. Awareness of the potential complications allows quicker diagnosis and may therefore be lifesaving. This article provides a practical guide to overcoming the complications of pacemaker insertion.

Methods for the assessment of the effects of drugs on coronary blood flow in man.

The methods currently available for measurement of coronary blood flow in man are reviewed and their advantages and limitations discussed. Most of the techniques are invasive and involve cardiac catheterization. The least invasive isotope techniques are either not quantitative or involve expensive equipment not available in many centres. Two of the most suitable methods for assessing the effects of drugs on coronary flow are coronary sinus thermodilution and isotope washout curves using 133xenon or [125I]-iodo-antipyrine. The ideal technique for measuring coronary blood flow has yet to be developed.

Echocardiographic abnormalities in type IV mucopolysaccharidosis.

Cardiac involvement is well recognised in most forms of the mucopolysaccharidoses but there is poor documentation of abnormalities specific to Morquio's syndrome (type IV mucopolysaccharidosis). Ten patients with the classic form or type A Morquio's syndrome with a median age of 12.5 years underwent echocardiographic assessment. Abnormalities were detected in six (60%) cases with mitral valve involvement in five patients and aortic valve disease in four. One patient had severe mitral leaflet thickening to the point of mitral stenosis. Two patients had evidence for myocardial involvement by way of echocardiographic ventricular hypertrophy. The cardiac lesions were haemodynamically mild. A cardiac murmur was audible in only three of the six cases. It is concluded that there is a high prevalence of silent cardiac abnormalities in patients with Morquio's syndrome with predominantly left sided valve involvement. Echocardiography should be part of the assessment of these patients and bacterial endocarditis prophylaxis should be advised for those with cardiac abnormalities.

Pseudoxanthoma elasticum presenting with myocardial infarction.

A 31 year old man presented with an anterior myocardial infarction. He had a history of recurrent gastrointestinal bleeding of obscure cause since childhood and peripheral vascular disease. A clinical diagnosis of the type 1 dominant form of pseudoxanthoma elasticum was supported by histological data from skin biopsy.