Randomized control trial investigating the influence of coffee on heart rate variability in patients with ST-segment elevation myocardial infarction.

BACKGROUND: Cardiac autonomic dysfunction post ST-segment elevation myocardial infarction (STEMI) has been linked to an excess risk of premature cardiovascular morbidity and mortality above those with normal autonomic function post-STEMI. AIM: The aim of this study was to evaluate the effect of acute ingestion of coffee on autonomic function and cardiovascular outcomes in patients with acute STEMI. DESIGN: Randomized control trial. METHODS: We randomized 103 patients with acute STEMI, admitted to our Coronary Care Unit, to receive regular coffee (caffeinated) or de-caffeinated coffee using a randomized controlled double-blinded design. Heart rate variability was assessed 5 days post-STEMI to assess the effect of caffeine on autonomic function. RESULTS: In the group randomized to regular coffee, parasympathetic activity increased by up to 96% (P = 0.04) after 5 days. There was no detrimental effect of regular coffee on cardiac rhythm post-STEMI. CONCLUSION: Coffee ingestion is associated with an increase in parasympathetic autonomic function immediately post-STEMI. Coffee was found to be safe and not associated with any adverse cardiovascular outcomes in the short term.

Is coronary angiography in unstable patients safe in district general hospitals without any on-site revascularisation?

BACKGROUND: Patients admitted to hospital with unstable angina or non-ST segment elevation myocardial infarction have a high risk of death, re-infarction or re-hospitalisation within the next 6 months. International guidelines recommend an early interventional strategy in moderate- to high-risk patients with pre-discharge coronary angiography. In the UK, such patients admitted to district hospitals have traditionally been transferred to tertiary centres for investigation and treatment. Due to the large numbers involved and scarcity of tertiary centre beds, this results in long delays before transfer. The objective of this study was to determine whether diagnostic cardiac catheterisation in moderate- to high-risk patients could be safely performed in hospitals without on-site revascularisation and whether this strategy led to earlier discharge times. METHODS: A retrospective audit was undertaken of all patients undergoing inpatient coronary angiography to a large district general hospital (DGH) after admission with a clinical diagnosis of unstable angina or non-ST elevation myocardial infarction over a 12-month period from April 2002 to March 2003. The main outcome measures were complications arising from coronary angiography and number of bed-days saved by allowing earlier discharge. RESULTS: 142 patients with non-ST elevation ACS who met 'high risk' criteria underwent inpatient angiography locally. Significant luminal coronary disease was present in 76% of patients but 49% were treated medically and discharged early. 32% of patients required transfer for percutaneous intervention (PCI) and 19% were referred directly for surgery. There was a high revascularisation rate (43%) even in patients who did not have elevated troponin levels on admission. No patients died or sustained a myocardial infarction as a result of angiography, and morbidity was minimal. Patients waited an average of 3 days for an angiogram locally, but transfer time to a tertiary centre was 9 days for PCI and 12 days for surgery. As almost half of all patients were discharged without requiring transfer for revascularisation, we estimate a total of 490 bed-days were saved over 12 months. CONCLUSION: Cardiac catheterisation in most 'high-risk' patients with non-ST elevation ACS is safe in DGHs without on-site PCI or surgery and frees up large numbers of acute medical beds by selecting out only those patients requiring onward referral for revascularisation.

Dual chamber pacemaker implantation via a double superior vena cava.

We present the chest X ray of a woman with sinoatrial node disease. She has had a dual chamber pacemaker implanted with each lead coursing through a separate superior vena cava.

Lack of significant effect of therapeutic propranolol on measurable platelet function in healthy subjects.

Propranolol, a non-selective beta blocker, was administered orally in therapeutic doses. The effects of a single dose (160 mg) and one week's treatment (80 mg twice a day) on platelet function were compared in healthy young subjects. There were no significant changes in circulating platelet aggregates, template bleeding time, platelet factor 3 availability and thromboxane beta 2 (TX beta 2) generation. Platelet aggregation responses as assessed by angle of slope and maximal percentage aggregation (all agonists) and lag phase (collagen) showed no changes of biological importance, although minor changes reaching significance were observed with some agonists. These findings suggest that propranolol does not significantly affect platelet function when taken at doses commonly encountered in clinical practice.

Single-breath breath-holding estimate of pulmonary blood flow in man: comparison with direct Fick cardiac output.

1. Resting pulmonary blood flow (Q), using the uptake of the soluble inert gas Freon-22 and an indirect estimate of lung tissue volume, has been estimated during breath-holding (Qc) and compared with direct Fick cardiac output (Qf) in 16 patients with various cardiac disorders. 2. The effect of breath-hold time was investigated by comparing Qc estimated using 6 and 10 s of breath-holding in 17 patients. Repeatability was assessed by duplicate measurements of Qc in the patients and in six normal subjects. 3. Qc tended to overestimate Qf, the bias and error being 0.09 l/min and 0.59, respectively. The coefficient of repeatability for Qc in the patients was 0.75 l/min and in the normal subjects was 0.66 l/min. For Qf it was 0.72 l/min. There was no significant difference in Qc measured at the two breath-hold times. 4. The technique is simple to perform, and provides a rapid estimate of Q, monitoring acute and chronic changes in cardiac output in normal subjects and patients with cardiac disease.

The relationship of symptoms to performance in paced patients with breathlessness.

Eighteen adult patients presenting with breathlessness associated with bradycardia, and whose breathlessness was diminished or abolished by permanent pacing, were studied at least one month after this procedure in order to examine the relationship between symptoms and exercise performance. All were pacing-dependent at rest and were studied over successive two-weekly periods at set rates of 50, 70 and 90 beats min-1 in a double-blind, balanced and randomized trial. The degree of breathlessness was closely related to exercise capacity judged by 6-min walk testing, effort scores and weekly pedometer distance. Overall results were worse at 50 beats min-1 than the two faster rates. For a given individual, changing of ventricular rate caused parallel alterations in symptoms and performance. The 6-min walking test was a useful guide to disability in these patients, tightly linked to the symptoms of effort and breathlessness, and may be of clinical value in assessing mild heart failure. The pedometer readings were influenced more by the patients' walking habits than by fitness.

Prediction of favourable responses to long term vasodilator treatment of pulmonary hypertension by short term administration of epoprostenol (prostacyclin) or nifedipine.

Eighteen patients with moderate to severe pulmonary hypertension were studied, nine with intracardiac shunts and nine without. The effects of an incremental infusion of epoprostenol (prostacyclin) (0.5-8 ng/kg per minute) or sublingual nifedipine (20-30 mg) were compared with the response to three months' treatment with oral nifedipine. Both epoprostenol and sublingual nifedipine caused a fall in pulmonary vascular resistance and pressure and a rise in cardiac output. Patients with intracardiac shunts had higher systemic blood flows than those without shunts. Exercise in the shunt group was accompanied by systemic desaturation and hyperventilation. Analysis of individual results showed that the size of the response was inversely related to the severity of the pulmonary vascular disease. A good long term response to nifedipine seemed to be as readily predicted by the resting control values for haemodynamic variables as by values after short term treatment. A favourable response was likely if the pretreatment mean pulmonary artery pressure was less than 50 mm Hg, the ratio of total pulmonary to systemic resistance was less than 0.7, or the ratio of mean pulmonary artery pressure to systemic artery pressure was less than 0.6. Short term vasodilator protocols may do harm. If such studies are carried out, an adequate dose range must be tried before the long term efficacy of an individual drug can be forecast.

Direct Fick cardiac output: are assumed values of oxygen consumption acceptable?

The use of assumed values of oxygen consumption has become an accepted practice in the calculation of direct Fick cardiac output. A survey showed that the assumed values in common use were derived from basal metabolic rate studies on normal subjects, a use which may not be valid. We have compared previous assumed values based on basal metabolic rate or cardiac catheterization studies with those obtained by direct measurement in 80 patients (age range 38-78 years) with various cardiac disorders. Comparison of the assumed and directly measured values of indexed oxygen consumption and the cardiac index showed large discrepancies, with over half the values differing by more than +/- 10% and many by more than +/- 25% from the measured value. Assumed values of oxygen consumption should be used with caution when calculating cardiac output during cardiac catheterization procedures, because large errors can result. The equations of LaFarge and Miettinen gave the closest approximation to the measured data and their use is recommended in preference to values predicted from basal metabolic rate studies.

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.

Factors that influence the outcome of primary pulmonary hypertension.

Factors predicting life expectancy in primary pulmonary hypertension have not been well defined. Thirty four cases of primary pulmonary hypertension that had been followed up until death or for at least five years were reviewed retrospectively. Patients were divided into three groups: 18 patients who died within five years of presentation to hospital; 12 who survived more than five years; and four who improved and who lived for more than five years. The age at onset was similar in the three groups and, like symptoms and sex, did not predict life expectancy. Right heart failure during the course of the disease was associated with a poor outcome. Radiographic evidence of cardiac enlargement and evidence of right heart strain on electrocardiogram at presentation was also predictive of survival for less than five years. Pulmonary arteriolar resistance was higher and cardiac output lower in those with the shortest survival times. There was no relation between pulmonary artery pressure and length of survival. Systemic resistance varied directly with pulmonary resistance and served to maintain systemic pressure. Presentation in or after pregnancy and patency of the foramen ovale were associated with longer survival. In four patients there was evidence of regression of the disease by cardiac catheterisation and lung histology. Primary pulmonary hypertension is a heterogeneous condition in which life expectancy varies widely.

Natural history of left ventricular function in neonatal Coxsackie myocarditis.

Three neonates are described who had severe congestive cardiac failure following Coxsackie-B virus infection. Overall left ventricular function was depressed and accompanied by regional differences in wall motion. Recovery has been gradual, and after 40 or more months of follow-up, all three infants still have evidence of myocardial damage. This provides further evidence linking myocarditis with dilated cardiomyopathy.

Regional pulmonary blood volume in patients with abnormal blood pressure or flow in the pulmonary circulation.

We studied the effects of a chronic increase in flow and of chronic hypertension on regional pulmonary blood volume and extravascular lung density (lung tissue and interstitial water per unit thoracic volume) in one group of patients with intracardiac, left-to-right shunt and in another group with Eisenmenger's syndrome or primary pulmonary hypertension. We used positron computerized tomography to measure regional lung density (transmission scans) and blood volume (labelling with 11CO). The distribution of pulmonary blood volume was more uniform in patients with a chronic increase in pulmonary blood flow than in normal subjects. There were also indications of an absolute increase in intrapulmonary blood volume. In patients with chronic pulmonary arterial hypertension, the regional distribution of blood volume was abnormally uniform, but there were no indications of substantial abnormalities in overall intrapulmonary blood volume.

Safety and effectiveness of a portable external automatic defibrillator-pacemaker.

Sudden cardiac death in the community can be reduced by early resuscitation. The commonest arrhythmia encountered in this setting is ventricular fibrillation. A portable external automatic defibrillator-pacing machine for use by emergency services and laymen after basic training, has recently been introduced. This device has a tongue-abdominal pathway for sensing the electrocardiogram and respiration, as well as delivery of current. In its automatic mode, the machine cannot defibrillate unless the patient's breathing and gag reflex are virtually absent. The decision-making characteristics of the machine were defined in isolation from the patient using simulated ECG signals and recordings of arrhythmias obtained during cardiac surgery and during electrophysiological studies. The pathway was evaluated separately by attaching it to a conventional defibrillator and using it in the elective cardioversion of 15 patients. Electrode sites were examined and creatine phosphokinase (CPK) and creatinine phosphokinase isoenzyme (CPKMB) release determined following conversion. Repeated playback of the same 34 minutes of selected recordings showed that decisions were consistent 95% of the time. Automatic pacing always occurred with asystole. ECG signals less than 0.35 mV in amplitude were not recognized, but a manual override switch could be operated in those circumstances where there was failure to act upon fine ventricular fibrillation. Defibrillation of 50% of the recordings of supraventricular and ventricular tachycardia did occur, but this could not have happened in practice unless the patient was unconscious, and in addition, the operator failed to countermand this decision. The tongue-abdominal pathway yielded good recordings of the ECG.(ABSTRACT TRUNCATED AT 250 WORDS)

Myocarditis in siblings leading to chronic heart failure.

Two brothers, aged 7 and 9, presented 4 years apart with progressive heart failure following a probable viral infection. Electrocardiograms of both showed widespread precordial Q waves. Cardiac catheterization in each case revealed almost equal right atrial, right ventricular and pulmonary artery pressures and poorer contraction of the right than left ventricle. High neutralizing antibody titres to Coxsackie B4 virus were found in the siblings and their mother. Widespread post-myocarditic scarring of both ventricles was found at autopsy on the elder brother. These findings provide further evidence that Coxsackie myocarditis accounts for some cases of dilated cardiomyopathy and suggest that familial factors may be important.

Quantitative measurement of intrapulmonary and extrapulmonary right-to-left shunt.

We have developed a new technique that enables the shunting of blood from the right to the left side of the circulation to be partitioned into a cardiac and a lung component. The effects of recirculation are minimal, and the method does not require on-line data analysis. Quantitative estimates of these components have been made in two normal dogs and in five patients with raised pulmonary arterial pressures, some of whom were known to have a patent foramen ovale. The results were compared with oxygen shunt measured during air breathing. A poorly soluble gas, nitrogen, radiolabelled with 13N in solution is injected first into a central vein while matched samples of blood are drawn from the pulmonary artery and the aorta. A second solution containing 13N is injected into the right ventricle and sampled from the aorta only. Standardized gamma-counting techniques were used to analyze both the injected radioactivity and the radioactivity in the samples. These two measurements enable us to calculate the total right-to-left shunt, the pulmonary shunt, and by subtraction the extrapulmonary cardiac shunt.