Xamoterol in sinus node disease.

A pharmacological alternative to pace-maker implantation would be useful in some patients with sinoatrial disorder particularly since the single lead ventricular system usually fitted has disadvantages. Xamoterol, a cardioselective beta-receptor partial agonist, has been shown to increase heart rate both in animals and in man. We, therefore, studied the effects of Xamoterol in patients with sinoatrial disease in a double blind, cross-over trial in 10 patients. Mean heart rates and number and duration of pauses were compared during the treatment phases of the trial with Holter monitoring. Mean heart rates were significantly increased between 01:00 h and 05:00 h (P < or = 0.02) and between 05:00 h and 09:00 h (P < or = 0.01) on Xamoterol. The number of sinus pauses were eliminated or reduced on Xamoterol in six patients, but there was an increased frequency in three patients. Xamoterol, therefore, does increase the heart rate and reduce the number of pauses in sinoatrial disorder, but only in some patients.

Labor analgesia with paravertebral lumbar sympathetic block.

BACKGROUND AND OBJECTIVES: Provision of labor analgesia continues to be a challenge for parturients with spine pathology or history of back surgery. METHODS: We report on the use of paravertebral lumbar sympathetic block for first stage labor analgesia in two parturients with spine pathology.

Development and preliminary clinical tests of an impedance sensing VDD recording pacemaker for diagnosis and research.

Episodes of serious but infrequently occurring cardiac arrhythmias can be difficult to detect and analyse, even with modern Holter monitoring. A previous diagnostic pacemaker developed by this group provided VVI pacing therapy and recorded intracardiac ECG signals but had no atrial sensing or impedance measuring capability. A new external diagnostic pacemaker system is described that has been developed to assist in diagnosing intermittent arrhythmias by selectively recording intracardiac signals. Unlike other ambulatory monitors, in addition to recording ECG, the device combines VDD pacing therapy with the capability of monitoring and recording intracardiac impedance and pressure waveforms through a temporary intracardiac lead. A PCMCIA memory card allows storage of 48 arrhythmic events of 21 seconds each. Twelve seconds of waveform are retained before the event occurs and nine seconds after. Data retrieval and processing is performed with a PC which reconstructs each waveform for display. The ECG provides data on cardiac rhythm while cardiac function is inferred from the haemodynamic signals. During simulated trials, 14 event types were presented to the system. All events were successfully detected and recorded. During in vivo clinical tests 83 waveform recordings were made. Impedance fluctuations with typical peak-to-peak values of 64 ohms were successfully recorded.

Coronary care follow-up study: acute care required immediately following thrombolytic therapy.

We carried out a prospective survey of the outcome of patients with 'suspected myocardial infarction', in order to determine where they should be nursed. The delay between onset, admission, transfer to the CCU, the sequelae and side-effects of thrombolytic therapy were noted and were documented prospectively. Of 217 admissions to CCU with a history of chest pain and suspected acute myocardial infarction during a four-month period (mean age was 62.8 years range 31 to 86 years) 202 fulfilled the criteria for suspected myocardial infarction. Streptokinase was given in 129 and alteplase in one patient. The delay between onset of pain and admission was < 4 h in 73, 4 to 12 h in 30 and > 12 h in 23. Elderly patients were just as likely as younger ones to receive thrombolytic therapy (Chi 2 = 3.6; P = 0.6). An eventual diagnosis of acute myocardial infarction was made in 133 of whom 100 received streptokinase. Dysrhythmia or shock was encountered in one-third of those given streptokinase and a quarter of the remainder. Reactions to streptokinase were recorded in 32 mainly hypotension or bradycardia alone or in combination. Forty-five per cent experienced either cardiac complications or drug reactions or both. During one month there were 57 admissions, 50 of whom arrived by ambulance. The mean delay between call out and arrival in the A&E department was 55 min. We concluded patients who are given thrombolytic therapy need close supervision and they should be nursed in a CCU or its equivalent.

Anesthesia for obstetric emergencies.

Anesthesia in an emergency presents an additional risk to the mother and may have some possibly harmful effects on the stressed fetus. The risk to the mother can be reduced by using regional anesthesia, whenever reasonable, and by taking measures to minimize the risk of aspiration of vomitus. The stressed fetus can be assisted, if not by a rapid delivery, by giving the mother oxygen to oxygenate the fetus and possibly by improving intervillous perfusion with a regional anesthetic.

Sinus node arrest and sino--atrial block.

Current epidemiological data suggest that sinus node dysfunction is a relatively uncommon condition in the pilot age group. Symptomatic pauses of any mechanism suggest disqualification from flying duties. Asymptomatic pauses (representing sino-atrial block or sinus node arrest) demand further investigation and regular follow-up. Idiopathic pauses greater than 2.5 s on an ambulatory ECG is abnormal and is likely to deny flying status.

Prevalence and morbidity of heart block in Devon.

In a survey in the Exeter area 139 patients with some degrees of abnormal atrioventricular conduction were notified by 282 family doctors. Per 100,000 of the population the prevalence of second-degree and thrid-degree heart block was estimated to be 17.3, of complete block past or present 15.6, and of complete block at the time of survey 13.1. Heart block was commoner in men than women, the sex ratio being 1.4 to 1; its prevalence increased steeply with age, and the morbidity rate was less than that reported by others. If the morbidity figures quoted in this survey are representative of the general population, it reaffirms the policy that pacemakers should be recommended for selected patients only.

Survival in sinoatrial disorder (sick-sinus syndrome).

A total of 381 patients with established (156) or potential (225) sinoatrial dysfunction were included in a 10-year prospective survey to determine the course of the disease and the benefits of pacing. With the exclusion of nine patients who were lost to follow-up, 61 were fitted with pacemakers. The overall survival of patients with established and potential dysfunction was similar and apparently indistinguishable from that of the normal population. Pacemaker implantation had little discernible effect on mortality though it reduced some incapacitating symptoms. These findings suggest that sinoatrial dysfunction is a relatively benign condition. Hence pacing should probably not be adopted as a routing measure but be reserved for patients with troublesome symptoms.

Survival in second degree atrioventricular block.

Two hundred and 14 patients with chronic second degree heart block were seen and followed up in the Devon Heart Block and Bradycardia Survey between 1968 and 1982. The patients were divided into three groups according to the type of block. In group 1 there were 77 patients with Mobitz type I block (mean age 69 years), in group 2, 86 patients with Mobitz type II block (mean age 74 years), and in group 3, 51 with 2:1 or 3:1 block (mean age 75 years). The five year survival was similar in all groups, being 57%, 61%, and 53% in groups 1, 2, and 3 respectively. The presence or absence of bundle branch block did not appear to influence prognosis. In particular, patients in group 1 without bundle branch block did not fare any better than those in group 2 both with and without bundle branch block. One hundred and three of the patients were fitted with pacemakers, the proportion being greatest in group 2. In each group a significantly larger number of paced patients survived than unpaced. The five year survival for all the paced patients in the study was 78% compared with 41% for the unpaced. Since the paced patients were slightly younger than the unpaced two age matched groups of 74 patients each were selected from the paced and unpaced patients, but the five year survival of those paced was still significantly better. It is concluded that in the patients in the present study chronic Mobitz type I block has a similar prognosis to that of Mobitz type II block. Unpaced patients with both types did very badly, whereas those fitted with pacemakers had a five year survival similar to that expected for the normal population. These results refute the benign reputation of chronic Mobitz type I block and imply that patients with this condition should be considered for pacemaker implantation on similar criteria to those adopted for patients with higher degrees of block.

Analysis of an open electrocardiograph referral service for family doctors.

The results of a questionary to investigate an open electrocardiograph (E.C.G.) service for family doctors suggest that the service is useful in diagnosis (26% of the E.C.G. reports were unexpected) and in management (the result of the E.C.G. led to specific treatment or alteration to regimen in 22% of cases and in a further 46% to reassurance). The results suggest that during the 45 weeks of the study many outpatient appointments were avoided.Undoubtedly an open E.C.G. service allows the family doctor to give a quicker and better service to his patients. For this reason and because of operational benefits to the hospital the service must be recommended.

Unexplained syncope--a diagnostic pacemaker?

We describe our initial experience with a pacemaker which performs the dual function of registering episodes of cardiac arrest and pacing the heart when necessary. The apparatus has a prolonged escape interval (2.30-2.65 seconds) and is capable of counting up to 128 "events." Twenty-five patients complaining of infrequent episodes of loss of consciousness have been studied. Blackouts ceased and episodes of ventricular standstill were recorded in 14 cases; the unit helped to establish a non-cardiac etiology for the attacks in two cases. It is suggested that a bradycardia-recording facility incorporated into a programmable pacemaker would provide a much needed tool in the diagnosis and management of patients with infrequent episodes of loss of consciousness in whom a cardiac mechanism is suspected but unproven.

Chronic sinoatrial disorder (sick sinus syndrome): a possible result of cardiac ischaemia.

Postmortem angiography was used to examine the blood vessels supplying the sinoatrial node in 25 subjects with chronic sinoatrial disorder (group 1). The results were compared with similar studies in 54 subjects who died of heart block and in whom sinus node function was normal (group 2). Although no significant lesion obstructing the blood flow to the sinus node was seen in the majority of those in group 1, there were abnormalities in seven cases, with reduced filling of the sinus node artery in five. In group 2 the sinus node artery filled normally in all cases despite major disease of the parent vessel in three. The combination of contralateral coronary artery disease with extensive atrial anastomoses was actively sought because this arrangement might predispose to a steal phenomenon. Such conditions were fully met in three cases in group 1 and two cases in group 2, and were found to a lesser extent in a further two cases in group 1 and three in group 2. Although coronary artery disease was unlikely to be the principal cause of sinus node dysfunction in most of the cases studied it was relatively common and may have been a factor in about one third. Improved survival after myocardial infarction may increase the number of patients with chronic sinoatrial disorder of ischaemic origin.

Is Mobitz type I atrioventricular block benign in adults?

OBJECTIVE: To assess the need for pacing in adults with chronic Mobitz type I second degree atrioventricular block (Mobitz I). DESIGN: Prospective study. SETTING: District general hospital. PATIENTS: 147 subjects aged > or = 20 years (age cohorts 20-44, 45-64, 65-79, and > or = 80) with chronic Mobitz I without second degree Mobitz II or third degree (higher degree) block on entry, seen from 1968 to 1993 and followed up to 30 June 1997. Sixty four had organic heart disease. The presence of symptomatic bradycardia was defined as highly likely in 47 patients (class 1); probable in 14 (class 2); and absent in 86 (class 3). INTERVENTIONS: Pacemakers were implanted in 90 patients for the following indications: symptoms in 74 and prophylaxis in 16. MAIN OUTCOME MEASURES: The main outcome measure was death, with conduction deterioration to higher degree block or symptomatic bradycardia the alternative measure. RESULTS: Five year survival to death was reduced in unpaced patients relative to that expected for the normal population (overall mean (SD) 53.5 (6.7)% v 68.6%, p < 0.001; class 3, 54.4 (7.3)% v 70.1%, p < 0.001). Paced patients fared better than unpaced (overall (mean (SD) five year survival 76.3 (4.5)% v 53.5 (6.7)%, p = 0.0014; class 3, 87.2 (5.4)% v 54.4 (7.3)%, p = 0.020; and organic heart disease, 68.2 (7.6)% v 44.0 (9.9)%, p < or = 0.0014). There were no deaths in the < 45 cohort. Survival to first outcome (main or alternative) was further reduced to 31.7 (5.0)% in 102 patients unpaced initially and 34.2 (5.7)% in class 3. Only the 20-44 cohort and patients with sinus arrhythmia had > 50% survival. CONCLUSION: Mobitz I block is not usually benign in patients > or = 45 years of age. Pacemaker implantation should be considered, even in the absence of symptomatic bradycardia or organic heart disease.

Sudden death in hypertrophic cardiomyopathy: associated accessory atrioventricular pathways.

Sudden death is a known but unpredictable complication of hypertrophic cardiomyopathy. We describe two patients who both had a strong family history of the disorder complicated by sudden death. Necropsy disclosed accessory bypass tracts, concealed in one and previously suspected in the other. One died from ventricular fibrillation and the other, who died outside hospital, had previously complained of palpitation. Arrhythmia complicating pre-excitation appears to be one of the factors responsible for sudden death in hypertrophic cardiomyopathy.

Chronic obstructive airway diseases. Current concepts in diagnosis and comprehensive care.

Physicians and paramedical personnel often find the early diagnosis and differentiation of obstructive airway diseases to be a challenging problem. The history and physical examination are often not enough to allow the physician to detect either the presence of, or determine the type of, disease present. Patterns of pulmonary function abnormality to determine the presence of obstructive or restrictive defects are discussed. Guidelines useful in the differentiation of obstructive airway diseases are presented. Once a patient with COAD is assessed, the physician needs to outline a therapeutic program after establishing goals with the patient. These goals include (1) improved ability for the patient to achieve relief from symptoms and (2) improved capacity to carry out the activities of daily living. The therapeutic modalities available for the comprehensive care of patients with COAD are discussed. These include general factors such as patient and family education, avoidance of smoking and other inhaled irritants, avoidance of infection, a minimum stress environment, high fluid intake, and proper nutrition. The appropriate use of the medications most commonly employed in the teatment of these patients, eg, bronchodilators, expectorants, antimicrobials, corticosteroids, cromolyn, digitalis, and diuretics, are individually discussed. The use of such respiratory therapy techniques as aerosol therapy, intermittent positive pressure breathing, and oxygen therapy are considered. Application of the specialty of rehabilitation medicine to patients with obstructive airway disease is described. This includes physical therapy with breathing retraining, clapping and postural drainage, and exercise reconditioning, occupational therapy with attention to energy conservation in activities of daily living, psychological considerations, and vocational rehabilitation. Definite benefits that can be demonstrated if the physician employs this type of systematic respiratory care program include a decrease in the frequency and duration of hospital admissions, socioeconomic gains from reduced hospitalizations, a reduction in anxiety, depression and somatic concern, the return of patients to positions of employment and the establishment of a better quality of life. Persistence in making sure the patient continues in a systematic program, including both pharmacological and nonpharmacological modalities, may be the means of assuring maintenance or even improvement in his health. The day-to-day treatment for the majority of patients should remain in the hands of the primary physician. However, community resources must be established to allow the primary physician to provide these patients with adequate comprehensive respiratory care. Development of three levels of care (the primary physician, community respiratory rehabilitation units, and the regional respiratory center) should make superior respiratory care available to every patient with obstructive airway disease.

Clinical trials of a dual-sensor diagnostic pacemaker.

The results of clinical trials of a dual-sensor diagnostic pacemaker are described. The system monitors and records intraventricular electrical and pressure waveforms using a special lead incorporating bipolar electrodes together with a piezoelectric pressure transducer. The recorded waveforms, which are shown in conjunction with Holter recordings made simultaneously, demonstrate the value of pressure measurements and illustrate several cardiac events, including an ECG pause, bradycardia, a pressure pause, ectopic beats and tachycardia. The pacing function of the device is shown and capture is demonstrated.

A dual-sensor diagnostic pacemaker for ambulatory cardiac monitoring.

Unexplained blackouts are a very common medical problem. Some patients presenting themselves at hospital with such symptoms have underlying bradycardia or extreme tachycardia with a profound decrease in cardiac output. Modern treatment of these patients may be highly effective but accurate diagnosis of their exact condition may be needed. A novel ambulatory dual-sensor diagnostic pacemaker has been developed to meet this requirement. The device monitors intracardiac ECG and intraventricular pressure through a special lead introduced perveneously into the right ventricle and detects and counts events such as bradycardia, tachycardia, pauses in the electrical or pressure signals and electrical interference. Analogue recordings of the electrical and pressure waveforms of 16 of these events can be made during the operating period of 3 weeks and pacing is incorporated via a specially-adapted commercial pacemaker if a prolonged episode of bradycardia or a pause is sensed. The device forms part of a complete diagnostic system also incorporating a computer which is used to set up the parameters of the diagnostic pacemaker and to display and analyse the recorded data.

Myocardial infarction: a comparison between home and hospital care for patients.

To compare the results of home and hospital treatment in men aged under 70 years who had suffered acute myocardial infarction within 48 hours 1895 patients were considered for study in four centres in south-west England. Four-hundred-and-fifty patients were randomly allocated to receive care either at home by their family doctor or in hospital, initially in an intensive care unit. The randomised treatment groups were similar in age, history of cardiovascular disease, and incidence of hypotension when first examined. They were followed up for up to a year after onset. The mortality rate at 28 days was 12% for the random home group and 14% for the random hospital group; the corresponding figures at 330 days were 20% and 27%. On average, older patients and those without initial hypotension fared rather better under home care. The patients who underwent randomisation were similar to those whose place of care was not randomised, except that the non-randomised group contained a higher proportion of initially hypotensive patients, whose prognosis was poor wherever treated. These results confirm and extend our preliminary findings. Home care is a proper form of treatment for many patients with acute myocardial infarction, particularly those over 60 years and those with an uncomplicated attack seen by general practitioners.

Prophylactic angiotensin II infusion during spinal anesthesia for elective cesarean delivery.

BACKGROUND: Angiotensin II may prove useful in treating regional anesthesia-induced hypotension in obstetric patients, because it causes less uterine vasoconstriction than do other vasoconstrictor drugs (such as phenylephrine). This study compared (1) maternal blood pressure and heart rate and (2) fetal status at delivery in parturients given either prophylactic angiotensin II or ephedrine infusion during spinal anesthesia for elective cesarean delivery. METHODS: Fifty-four women were randomized to receive either angiotensin II or ephedrine infusion intravenously during spinal anesthesia for elective cesarean section delivery. Simultaneous with subarachnoid injection, infusion of angiotensin II (2.5 microg/ml) or ephedrine (5 mg/ml) was initiated at 10 ng x kg(-1) x min(-1) and 50 microg x kg(-1) x min(-1), respectively. The rate of each infusion was adjusted to maintain maternal systolic blood pressure at 90-100% of baseline. RESULTS: Cumulative vasopressor doses (mean+/-SD) through 10, 20, and 30 min were 150+/-100, 310+/-180, and 500+/-320 ng/kg in the angiotensin group and 480+/-210, 660+/-390, and 790+/-640 microg/kg in the ephedrine group. Maternal heart rate was significantly higher (P < 0.001) during vasopressor infusion in the ephedrine group than in the angiotensin group. Umbilical arterial and venous blood pH and base excess were all significantly higher (P < 0.05) in the angiotensin group than in the ephedrine group. CONCLUSIONS: Angiotensin II infusion maintained maternal systolic blood pressure during spinal anesthesia without increasing maternal heart rate or causing fetal acidosis.