A comparison of nifedipine once daily (Adalat LA), isosorbide mononitrate once daily, and isosorbide dinitrate twice daily in patients with chronic stable angina

The efficacy of nifedipine gastrointestinal therapeutic system (GITS), 60-90 mg o.d., isosorbide dinitrate, 40-60 mg b.d., and isosorbide mononitrate slow-release, 50-100 mg o.d. was assessed in a six week double-blind, parallel-group study in patients with stable angina on chronic beta-blocker treatment. Of 339 patients who entered the study, 229 were eligible for the valid case analysis of efficacy and 335 for the safety analysis. Nifedipine GITS was significantly better than isosorbide dinitrate (P < or = 0.025) in prolonging time to 1 mm ST-segment depression, time to maximum ST-segment depression, time to occurrence of angina and total exercise duration, in addition to reducing the number of angina attacks and glyceryl trinitrate consumption after six weeks therapy. Nifedipine GITS was also significantly better than isosorbide mononitrate (P < or = 0.025) in prolonging time to occurrence of angina and time to 1 mm ST-segment depression after six weeks therapy. The incidence of headache was considerably higher in both the isosorbide dinitrate and isosorbide mononitrate groups (40% and 41%, respectively) than in the nifedipine GITS group (9.5%, P < or = 0.001), and was the main reason for withdrawal from the study (isosorbide dinitrate 18/99, isosorbide mononitrate 17/99, nifedipine GITS 2/95). Peripheral oedema was more common in patients treated with nifedipine GITS (12.5%) compared to nitrates (2% in both groups, P < or = 0.01), but resulted in withdrawal of only one patient (treated with nifedipine GITS). This study suggests that the efficacy and tolerability of nifedipine GITS is superior to long acting nitrates as second-line therapy to beta-blockade in the treatment of chronic stable angina.

Noonan's cardiomyopathy: a non-hypertrophic variant

OBJECTIVE

To describe the association of the Noonan's phenotype and a primary, familial non-hypertrophic cardiomyopathy with restrictive pathophysiology.

DESIGN

Observational study.

SETTING

Tertiary cardiac referral centre.

PATIENTS

Affected family members.

METHODS

Two generations of a single family were examined and a description of the clinical characteristics and electrocardiographic, echocardiographic, and haemodynamic data of those affected is given.

RESULTS

Three family members have classic Noonan's phenotype and all have a non-dilated, non-hypertrophic cardiomyopathy. Inheritance is autosomal dominant but with variable penetrance. The electrocardiograms show increased left ventricular voltages in two patients. On echocardiography left ventricular wall and internal end diastolic dimensions are normal, and there is considerable bilateral atrial enlargement. Systolic function is moderately impaired in one patient and mildly impaired in another. Doppler echocardiography showed restrictive pathophysiology as an early end of left ventricular filling and considerable reversal of flow in the superior vena cava during atrial systole.

CONCLUSION

Hypertrophic cardiomyopathy is well described in Noonan's syndrome. This is the first report of a non-hypertrophic cardiomyopathy with echocardiographic and haemodynamic features of restrictive pathophysiology.

Atrial permanent pacing for sinus node dysfunction with absent right superior vena cava

In patients with sinus node dysfunction and normal atrioventricular conduction, single chamber atrial pacing (AAI or AAIR mode) represents the most physiological treatment. Sinus node dysfunction is recognised in association with an absent right superior vena cava, and we present a case in which complete resolution of symptoms was achieved with endocardial atrial permanent pacing.

Doppler echocardiography of double orifice of the left atrioventricular valve in atrioventricular septal defect

A left atrioventricular valve having a double orifice is a rare congenital abnormality, and is most commonly described in association with atrioventricular septal defect. We report the Doppler echocardiographic findings of this abnormality and present a case where limited surgical repair has resulted in a favourable outcome.

Normal and stenotic human aortic valve opening: in vitro assessment of orifice area changes with flow

The ability to measure aortic valve area clinically has emphasized the need to understand the changes in aortic valve orifice area during flow. To compare the performance of normal and stenotic human aortic valves we used a pulsatile flow model that simulated in vivo flow conditions. Five normal autopsy specimens and 15 stenotic valves removed at operation were mounted into the model. Valve function was assessed by analysis of video recordings of valve leaflet motion during flow. Over the flow rates tested normal valves demonstrated a linear increase in orifice area. There was no resistance to leaflet opening and valve closure was rapid. The majority of stenotic valves demonstrated an increase in orifice area at low flow rates. No valve showed any increase in maximal area beyond flow rates of 3 l min-1. Increased leaflet resistance of these abnormal valves resulted in notably slower opening and closing rates. In patients with a high cardiac output and severe stenosis, overestimation of the anatomic orifice area derived by the Gorlin equation can result. This is not related to variability in maximal orifice area.

In vitro measurement of stenotic human aortic valve orifice area in a pulsatile flow model. Validation of the continuity equation

Aortic valve orifice area estimation in patients with aortic stenosis may be obtained non-invasively using several Doppler echocardiographic methods. Their validity has been established by correlation with catheterization data using the Gorlin formula, with its inherent limitations, and small discrepancies between the methods are present. To evaluate these differences further, 15 patients with severe aortic stenosis (mean transvalvular gradient 70, range 40-130 mmHg) had aortic valve area estimations by Doppler echocardiography using two variations of the continuity equation. The intact valves removed at valve replacement surgery were then mounted in a pulsatile model and the anatomical area was measured (mean 0.67 +/- 0.17 cm-2) from video recordings during flow at 5.4 l min-1. Aortic valve area calculated using the integrals of the velocity-time curves measured at the left ventricular outflow tract and aortic jet (mean 0.65 +/- 0.17 cm2) correlated best with the anatomical area (r = 0.87, P less than 0.001). The area derived by using the ratio of maximum velocities from the left ventricular outflow tract and aortic jet (mean 0.69 +/- 0.18 cm2) also correlated well with the anatomical area (r = 0.79, P less than 0.001). The index between the left ventricular outflow tract and aortic jet maximum velocities was less than or equal to 0.25 in all. In patients with severe aortic stenosis the aortic valve area can be reliably estimated using Doppler echocardiography.

Balloon dilatation of the aortic valve in a pulsatile flow model: assessment of the mechanisms and the magnitude and duration of changes in valve area and gradient

Eighteen stenotic aortic valves (17 removed at operation) mounted in a pulsatile flow duplicator were dilated with a balloon catheter. Sequential measurements showed that the valve area initially increased from a mean (SD) of 0.52 (0.16) to 0.78 (0.17) cm2. It was 0.73 (0.16) cm2 five minutes after dilatation and this was little changed at four weeks (0.70 (0.15) cm2). Initially the mean transvalvar gradient fell significantly from 54 (27) to 32 (8) mm Hg but increased to 35 (10) mm Hg at five minutes and to 40 (11) mm Hg at four weeks. In six valves stretching of the orifice was the only mechanism responsible for the changes while in the remainder there was tearing through commissures with a greater initial increase in area (0.31 v 0.18 cm2) and a smaller decrease in area at five minutes (0.03 v 0.08 cm2). Fractures of calcific deposits in non-commissural positions were seen in one valve only. This laboratory study of isolated aortic valves showed a significant but small increase in valve area after balloon dilatation, which was greater when commissural tearing had occurred. Recoil of the stretched orifice was complete at five minutes and there was little further change over the next four weeks.

Exercise myocardial perfusion scintigraphy with technetium-99m methoxy isobutylisonitrile: a comparative study with thallium-201

The evaluation of technetium-99m methoxy isobutylisonitrile for the diagnosis of coronary artery disease requires comparative validation against thallium-201, the established perfusion imaging agent. We have compared myocardial and lung uptake of both radiotracers following maximal exercise in 52 patients: 40 with angiographically proven coronary disease. Qualitative and quantitative image analysis showed the diagnostic sensitivity of technetium-99m methoxy isobutylisonitrile to compare favourably with that of thallium-201 as reflected by the mean number of ischaemic segments identified: 5.6 +/- 2.5 vs 4.8 +/- 2.1 by qualitative analysis, and 5.7 +/- 3.2 vs 5.0 +/- 2.6 segments by quantitative analysis. More reversibly ischaemic segments per patient were identified with technetium-99m methoxy isobutylisonitrile than with thallium-201: 3.6 +/- 2.3 vs 1.8 +/- 1.9. There was a higher exercise myocardial to background count ratio with technetium-99m methoxy isobutylisonitrile: 3.16:1 vs 2.58:1, and the mean exercise lung uptake normalised to left ventricular uptake ('lung index'), was lower for technetium-99m methoxy isobutylisonitrile than for thallium-201 (36 +/- 8% vs 40 +/- 10%). Five of the six patients with abnormal elevation of the thallium-201 exercise lung index also had elevation of the technetium-99m methoxy isobutylisonitrile exercise lung index, and all had extensive coronary artery disease. These results indicate that technetium-99m methoxy isobutylisonitrile is at least as effective as thallium-201 for detecting exercise induced myocardial ischaemia. However, technetium-99m methoxy isobutylisonitrile provides a better image quality and may be a more sensitive marker of defect reversibility. For both radiotracers lung uptake is increased with extensive coronary artery disease and measurement of this variable provides prognostic information.

Laser thermal angioplasty probe ("hot tip") temperature: effects of flow

The temperature developed by the laser thermal ("hot tip") probe during arterial recanalisation is primarily dependent on the rate of energy delivery and the rate of dissipation to the surrounding medium. While higher probe tip temperatures enhance the efficacy of atheroma ablation, so too is the incidence of adverse effects increased. We studied the temperature developed in the probe tip in an artificial circulation using both saline and blood. In saline the peak probe temperatures were limited to 100 degrees C (boiling point), falling with each increment in flow. Small discrepancies in probes at different times and may be due to malalignment of the optical fibre-metal cap coupling, temperature measurement inaccuracy, tip insulation, or generator output instability. In blood, charring and clot formation insulated the tip raising the temperature (up to 700 degrees C within 5 seconds at 10 W) but also retarded dissipation of heat to the surroundings. The degree of clot and char formation was critical in determining subsequent thermal responses in any particular probe. The unknown rate and quantity of char buildup and changing blood flow during in vivo angioplasty are likely to be important obstacles to developing a reliable thermal feedback control system.

His bundle ablation with the laser thermal probe ("hot tip"): a feasibility study

Successful percutaneous ablation of the bundle of His requires accurate localization together with delivery of the minimum effective energy to avoid unwanted effects. The energy output from laser sources can be controlled very precisely but is not easily directed to the bundle of His using conventional fiber optics. The laser thermal probe ("hot tip") consists of an optical fiber and a terminal metal cap that is rapidly heated during energy delivery. When applied to cadaver hearts at energies of 100-150 joules (10 watts for 10-15 seconds) the 2.0-mm diameter peripheral artery probe was able to damage the bundle of His without extensive surrounding damage. The right ventricular free wall and interventricular septum were perforated during some applications at these energies leaving a tract with a diameter of less than 2.0 mm. The atrioventricular (AV) membranous septum, Foramen Ovale, right atrial appendage, and septal leaflet of the tricuspid valve were more resistant at these energy levels and perforations were always less than 1.0 mm in diameter. The probe was modified for use during electrophysiological studies and good quality unipolar electrograms were recorded from the metal cap confirming that the probe could be accurately positioned adjacent to the bundle of His. The laser thermal probe deserves further study as a "self directing" ablation tool.

Coronary angioplasty and left ventricular function in single vessel coronary artery disease

Left ventricular function was investigated in 86 patients with single vessel coronary artery disease before and three to six months after successful angioplasty. Before angioplasty thallium-201 perfusion scintigraphy and technetium-99m gated equilibrium ventriculography in most patients showed that stress testing (exercise and ice water stimulation and isometric handgrip respectively) induced myocardial perfusion defects that were associated with a mean (SD) drop in left ventricular ejection fraction from 64 (6)% to 56 (7)%. After angioplasty there was residual coronary stenosis of less than or equal to 20% of the diameter of the vessel in 78 patients (group 1) and of between 20 and 50% in eight patients (group 2). After the procedure the perfusion defects seen during stress resolved in 86% of group 1 and in 87% of group 2. Despite the apparent improvement in myocardial perfusion left ventricular dysfunction persisted in group 2--that is during stress the left ventricular ejection fraction fell from 65% (6) to 56% (5). In group 1, on the other hand, the improvement in myocardial perfusion was associated with significant improvement in left ventricular function with a normal increase in ejection fraction from 63 (5) at rest to 67 (6) during stress. Radionuclide studies, one to six weeks after angioplasty in 30 group 1 patients showed continuing left ventricular decompensation during stress in nine (30%) of them despite correction of perfusion defects. But reinvestigation three to six months after the procedure showed recovery of left ventricular function with an increase in ejection fraction from 66 (5) at rest to 69 (7) during stress. These data indicate that coronary angioplasty procedures that give a residual stenosis of </= 20% improve myocardial perfusion and the response of the left ventricle to stress. The functional improvement may be delayed for up to three months, however, possibly because arterial healing at the angioplasty site is delayed. On the other hand, when the residual stenosis is between 21 and 50% of the diameter of the vessel subclinical left ventricular dysfunction during stress may persist indefinitely.

The evaluation of ventricular function using gated myocardial imaging with Tc-99m MIBI

Left ventricular function is an important prognostic indicator in patients with coronary artery disease. We have assessed a method of providing this information as an adjunct to myocardial perfusion imaging using Tc-99m MIBI (2-methoxy-2-methyl-isopropyl-1-isonitrile). Two separate studies, at rest and during exercise, were performed following an injection of 400-600 M Bq of Tc-99m MIBI in 62 patients. Cardiac gating permitted excellent myocardial edge definition during the cardiac cycle. Radionuclide fractional shortening (RFS) was calculated from the anteroposterior (AP) and the septum to lateral wall (SL) axes in diastole and systole. Results were compared with echocardiographic fractional shortening (EFS) and the ejection fraction (EF) obtained from the gated equilibrium blood pool using Tc-99m-labelled red blood cells. The RFS in the AP axis correlated closely with echocardiographic FS (r = 0.89, P less than 0.001). The RFS in both axes was averaged to provide a global RFS. Global RFS correlated closely with LV radionuclide EF (r = 0.83, P less than 0.001). Inter- and intra-observer reproducibility studies have shown a variability for the procedure of less than 10%. In conclusion, gated perfusion imaging with Tc-99m MIBI, provides useful functional information as an adjunct to perfusion imaging.

A pharmacokinetic study of cilazapril in patients with congestive heart failure

1. The pharmacokinetics of cilazapril and the inhibition of angiotensin converting enzyme (ACE) were investigated in 10 patients with congestive heart failure, NYHA class II-III, receiving diuretics with or without digoxin. 2. Patients received 0.5 mg and 1 mg cilazapril on the first 2 days, followed by 0.5 mg or 1 mg daily for the next 8 weeks, in a single-blind study. Plasma cilazaprilat concentrations and plasma ACE activities were measured by radioenzymatic methods up to 24 h after the first and last doses. 3. After the initial 0.5 mg dose of cilazapril, a mean maximum plasma concentration of cilazaprilat of 6.8 ng ml-1 was observed at 2.3 h. Concentrations declined up to 8 h with a mean half-life of 5.8 h, followed by slower decrease to 24 h. Total clearance, based on data to 24 h, was estimated at 8.5 l h-1, with three-fold inter-individual variation. Mean maximum plasma ACE inhibition was 87%, decreasing to 65% at 24 h. 4. In the multiple dose phase of the study, four patients received cilazapril 0.5 mg daily, and six patients 1 mg daily. Cilazapril accumulation for the 0.5 mg group averaged 77%, but steady state concentrations for the 1 mg group were less than double those of the 0.5 mg group. ACE inhibition profiles at steady state were similar for both groups, and they differed from first dose data only in a somewhat lower inhibition at 24 h. 5. Historical comparison of the first-dose data with those for healthy young volunteers at identical dosage revealed only minor differences in kinetic parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

Thermal effects of stationary "hot tip" laser coronary probes: an in vitro assessment

Percutaneous laser thermal probe angioplasty requires sufficient laser probe flexibility to access the coronary tree. This may entail a loss of axial strength and the resultant slow advancement may lead to unwanted heating of the normal coronary artery proximal to the lesion. To assess the lateral thermal effects of stationary coronary laser probes, laser thermal energy (50-150 J) was delivered to 25 coronary artery segments (diameter 1.9-4.0 mm) in a perfused cadaver heart preparation using a 1.7 mm tip probe. Adherence to the vessel wall occurred in 19 segments, endothelial charring in 8 segments, and perforation in 3 segments. Endothelial charring was seen in 8 of 13 nonperfused segments but in 0 of 12 segments perfused at 60 ml/minute (P less than 0.01). In all three perforations the vessel to probe diameter ratio was less than 1.6:1, perfusion was absent, and traction to dislodge the adherent probe was necessary. Lateral wall damage is a complication of stationary laser probes: smaller-tipped probes which are advanced rapidly at the time of energy delivery may enhance the safety margins of coronary laser thermal probe angioplasty.

Fetal complete heart block

In a series of over 6000 patients referred for fetal echocardiography during an eight year period, 37 fetuses were found to have complete heart block. There were 16 cases of isolated heart block and 21 cases associated with structural heart disease. All mothers of fetuses with isolated complete heart block had evidence of circulating syndrome Sjögren A antibody (Ro). Only one mother had clinical evidence of connective tissue disease. In the 21 cases associated with structural heart disease there were 17 cases of atrioventricular septal defect, one case of secundum atrial and perimembranous ventricular septal defects, two cases of tetralogy of Fallot, and one case of pulmonary stenosis. All fetuses with atrioventricular septal defects and complete heart block had left atrial isomerism. Additional abnormalities of the great arteries were often found in this group; these were double outlet right ventricle, transposition of the great arteries, pulmonary atresia, coarctation of aorta, and stenosis of the pulmonary or aortic valves. Intrauterine congestive heart failure was a feature of four cases in the group with isolated complete heart block and 11 cases of the group with associated structural heart disease. The outcome in the fetuses with isolated complete heart block was better than in those with heart disease: 12 of the 16 fetuses are alive, two of them have a pacemaker. But only three of the group of 21 fetuses with cardiac malformation are alive, and two of them have a pacemaker.

Experience with flecainide for the treatment of cardiac arrhythmias in children

We treated 22 children, aged 3 days to 16 years 6 months (median 11 years 1 month), with flecainide for a variety of arrhythmias where a Class I agent was indicated. In 16, conventional antiarrhythmic treatment had failed. Structural heart disease was present in nine. The arrhythmia was paroxysmal re-entry atrioventricular tachycardia in nine; paroxysmal atrial tachycardia, flutter or fibrillation in five; paroxysmal ventricular tachycardia in five and frequent ventricular extrasystoles (with couplets) in three. Sinus rhythm was achieved in all four children who received flecainide during tachycardia (three received intravenous flecainide, one oral). During follow-up of 3-24 months (median 12 months), arrhythmia control was obtained in 13 children (59%). Combination therapy was used in seven of these; with digoxin in four and a beta blocker in three. Flecainide doses used in this study ranged from 1-11 mg kg-1 day-1 (median 4 mg kg-1 day-1), 25-297 mg m-2 day-1 (median 113 mg m-2 day-1). The median, pre-dose flecainide concentration in those responding to therapy was 225 micrograms l-1 and in those failing to respond was 417 micrograms l-1. An arrhythmogenic effect occurred in one child.

Obstetric importance, diagnosis, and management of fetal tachycardias

During 1980-7, 23 pregnancies of 22-38 weeks' duration were investigated for fetal tachycardia. Twelve were cases of supraventricular tachycardia, eight of atrial flutter, and three cases in which the rhythm varied between supraventricular tachycardia and atrial flutter. In 11 cases the fetus had developed non-immune fetal hydrops before referral; 12 cases were non-hydropic at referral but one of this group of fetuses became hydropic during treatment. No relation was found between the rate or type of arrhythmia and the presence or absence of intrauterine heart failure. One non-hydropic infant was delivered electively prematurely. Maternal antiarrhythmic treatment was instituted in the remaining 22 cases. Conversion of the arrhythmia was achieved with digoxin alone in five cases and with a combination of digoxin and verapamil in nine. Control of the arrhythmia was achieved in seven of the 10 non-hydropic fetuses, and all were delivered at term with no deaths. Of the 12 hydropic fetuses, control was achieved in seven. Only three of the hydropic fetuses were delivered close to term. There were two deaths, both in the hydropic group. Of the whole group, five neonates suffered severe complications of prematurity. In this series the main benefit of treatment appeared to be in prolonging gestation of those hydropic fetuses in which conversion was achieved.

Mianserin and trazodone for cardiac patients with depression

In a placebo controlled double-blind cross-over study, the cardiovascular and antidepressant effects of three weeks' treatment with mianserin (30-80 mg daily) and trazodone (150-400 mg daily) were studied in depressed patients who had co-existant cardiac disease. In 14 of the 16 patients, no haemodynamic deterioration occurred with either drug. Two patients withdrew from the study. One with coronary artery disease, whose concomitant medication included a calcium-antagonist and a beta-adrenoceptor blocker and who developed severe postural hypotension after his first dose of trazodone while the other had an increased frequency of transient cerebral ischaemic attacks with both mianserin and trazodone, but not with placebo. Mianserin and trazodone are comparable for both antidepressant efficacy and paucity of cardiovascular effects. Although unwanted effects were generally mild, the incidence of dizziness was greater in those patients receiving trazodone. Caution is advised, however, when prescribing either drug to patients with transient cerebral ischaemic attacks or those with coronary artery disease receiving medication.

Can the site of origin of ventricular extrasystoles enhance the localisation of exercise-induced ischaemia?

Previous work from the Departments of Cardiology and Nuclear Medicine, Guy's Hospital, London, has enabled an atlas of the electrocardiographic appearances of ectopics from individual ventricular sites to be compiled. This has been used to investigate the relationship between regions of myocardial ischaemia and the site of origin of exercise-induced ventricular arrhythmias. Two hundred and ten patients underwent maximal exercise testing on a bicycle ergometer, prior to thallium scintigraphy. All 12 leads of the electrocardiogram were recorded simultaneously at rest, immediately post-exercise and then for several minutes afterwards. Thallium scintigraphy was performed immediately and 4 hours post-exercise. Twenty-nine patients of the 210 had ventricular arrhythmias on exercise. Two had dilated (congestive) cardiomyopathy, 1 had hypertrophic cardiomyopathy and 26 were subsequently proven to have ischaemic heart disease. Fifteen of those patients with coronary artery disease and ventricular arrhythmias had otherwise negative exercise tests. Patients with reversible posterior (circumflex) defects had right bundle branch block extrasystoles with a limb lead QRS axis of -60 degrees to -150 degrees. Reversible inferior defects demonstrated ectopic activity with left bundle branch block and a superior axis. Ectopics of septal origin could present with either right or left bundle branch block and an inferior axis from the upper septum, or superior axis from the lower septum. In patients with ischaemic heart disease the 12-lead electrocardiographic appearance of ventricular arrhythmias enables their site of origin to be localised thus suggesting ischaemia in a particular coronary artery territory.

Intravenous and oral amiodarone for arrhythmias in children

Oral amiodarone was administered to 30 children (aged one week to 14 years) for treatment of resistant or life threatening tachycardias. Five children received initial intravenous medication. The mean duration of oral treatment ranged from two weeks to 64 months (mean 23 months). Infants required a higher oral dose than older children when this was calculated on the basis of body weight but not when it was calculated on the basis of body surface area, indicating that the prescribed dose of amiodarone for infants should be calculated on the basis of body surface area. Although plasma concentrations of amiodarone were similar in infants and children, the plasma concentration of the metabolite desethylamiodarone was lower in infants. The arrhythmias were effectively controlled, by amiodarone alone in 19 and by amiodarone in combination with other drugs in nine children; amiodarone was ineffective in the remaining two children. Unwanted effects were common but were not significantly related to the dose, duration of treatment, or plasma concentration of amiodarone when group results were analysed. Grey facial skin pigmentation developed in two patients who received high cumulative doses of amiodarone and in whom plasma concentrations of amiodarone were high. Four children with biochemical hepatic dysfunction had high plasma concentrations of amiodarone and a further four children who experienced sleep disturbance had required high doses of amiodarone.

Right ventricular outflow tract tachycardias in patients without apparent structural heart disease

We have investigated 13 patients with monomorphic ventricular tachycardia which originated from the right ventricular outflow tract. No patient had evidence of organic heart disease. There were 3 males and 10 females, aged 13-53 years. All had non-invasive investigations including an exercise electrocardiogram, chest radiography, echocardiograms and gated blood pool scintigraphy. Ten patients underwent cardiac catheterisation. Five patients had a prolonged QTc on their resting electrocardiogram. The remaining investigations showed no evidence of organic heart disease. Ten patients had ventricular arrhythmias which were completely suppressed during maximal exercise but which recurred in the immediate post-exercise period. A further 2 patients with no arrhythmias before exercise had ventricular tachycardia in the post-exercise period. Electrophysiology studies were performed in 5 patients with syncopal episodes, suggesting an automatic focus in 4. Four patients required specific antiarrhythmic surgery for symptoms refractory to medical therapy. Pace-mapping at operation confirmed the origin to be within the right ventricular outflow tract in all. Thus, we have identified a group of patients who have ventricular tachycardia originating from the right ventricular outflow tract in whom there is no apparent structural heart disease. Their arrhythmias are influenced by exercise and are probably due to an automatic focus. Four patients required surgery for ventricular tachycardias and recurrent syncopal episodes refractory to medical therapy.

Measurement of plasma disopyramide as a guide to paediatric use

We have studied the relationship between age, daily dose, plasma concentration and clinical efficacy of disopyramide in a group of paediatric patients. Twelve children with ventricular and 3 with supraventricular arrhythmias were treated with oral disopyramide. The initial dose was 3-6 mg/kg per day. This was adjusted until a pre-dose plasma concentration greater than 2 mg/I was achieved. Seven patients were judged to have responded to the treatment on clinical criteria. No symptoms or signs of toxicity were observed. In some of the children the dose of disopyramide required to achieve a plasma concentration greater than 2 mg/l was greatly in excess of the normal adult dose. Generally the youngest children required the highest dose, but the variation was wide. The dose could not be predicted from the age, the body weight or the surface area of the patient. In children high doses of disopyramide may be needed to achieve effective plasma concentrations of the drug; such doses are not associated with adverse effects. Measurement of the plasma concentration is necessary to guard against premature termination of therapy.

Effect of exercise on ventricular response to atrial fibrillation in Wolff-Parkinson-White syndrome

Ten patients with Wolff-Parkinson-White syndrome underwent cardiac electrophysiological study extended to include the induction of atrial fibrillation at maximum exercise in the upright position. This was performed using a new temporary bipolar lead with a helical active fixation tip for atrial pacing. The highest rate of atrioventricular conduction via the accessory pathway was greater during exercise than at rest in all 10 patients (mean increase 28%). In three cases the resulting ventricular rate exceeded 300 beats/min, but no patient had severe symptoms or ventricular arrhythmias. The exercise induced enhancement of accessory pathway conduction may significantly but unpredictably affect the risk from spontaneous atrial fibrillation especially in patients with coronary artery disease or in those taking antiarrhythmic drugs. The test procedure was sufficiently simple and well tolerated to be included in our routine electrophysiological investigation.

Ventricular arrhythmias. A guide to their localisation

An electrocardiographic atlas of ventricular tachycardias was produced by pacing 27 epicardial sections of the heart and the mitral papillary muscles to simulate focal ventricular arrhythmias and simultaneously recording their 12 lead electrocardiographic appearances. One hundred and twenty nine patients undergoing cardiac surgery were studied. In five patients all 27 epicardial sites were paced at operation and in 124 individual sections were paced postoperatively with temporary epicardial wires and the electrocardiograms analysed in terms of frontal and horizontal plan QRS axis, maximum limb lead QRS amplitude, and QRS duration. Each ventricular region paced produced a distinctive 12 lead electrocardiographic pattern. Simulated right ventricular arrhythmias had either inferior frontal plane QRS axes (from the anterobasal region) or superior frontal plane QRS axes (from the apical and posterior right ventricular sections). Horizontal plane QRS axes were directed leftwards, with some posterior shift in the anteroapical regions. Simulated arrhythmias from the base of the left ventricle (anteriorly and laterally) had inferior frontal plane QRS and anterorightward horizontal plane QRS axes. Left ventricular arrhythmias with a superior frontal plane QRS axis were readily distinguished by their horizontal plane QRS axes: posterorightwards from the anterior and anterorightwards from the posterior left ventricular sections. Standard errors of the paced QRS axes for the various epicardial sections paced postoperatively ranged from 3.0 degrees to 6.0 degrees using the frontal plane axis. The electrocardiogram was most accurate in localising ventricular arrhythmias from the anterior left ventricle and least accurate for those arising from the inferior right ventricle. The appearance of the paced electrocardiograms was slightly modified by underlying disease such as myocardial infarction and left ventricular hypertrophy. This atlas may be useful in comparing the localisation of ventricular tachycardia with the site of underlying cardiac disease and may facilitate mapping in patients with refractory ventricular tachycardia requiring ablation (either surgical or by high energy impulses).

Acupuncture needles as a cause of bacterial endocarditis

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High-performance liquid chromatographic measurement of amiodarone and its desethyl metabolite: methodology and preliminary observations

A high-performance liquid chromatographic technique is described for the measurement of amiodarone and its desethyl metabolite in plasma. Preliminary observations are presented on the concentrations of metabolite found during the early stages of chronic amiodarone therapy. A case history is outlined in which noncompliance during treatment with amiodarone was confirmed by measurement of the ratio of desethylamiodarone to amiodarone concentrations.

An assessment of beta-adrenoceptor blockade in man by prizidilol hydrochloride

1 Prizidilol hydrochloride (SK&F 92657) is a new compound which causes both arteriolar dilatation and beta-adrenoceptor blockade. The effect of a single oral dose on the responses of heart rate and blood pressure to isoprenaline infusion has been studied in healthy volunteers. 2 Isoprenaline heart rate dose-response curves showed parallel shifts to the right after oral prizidilol, indicating antagonism by this compound at beta-adrenoceptors in the heart. 3 Isoprenaline dose-response curves for decreases in diastolic blood pressure also showed shifts to the right after oral prizidilol, providing evidence of beta-adrenoceptor antagonism by this drug in peripheral resistance vessels. 4 The peak effect of a 40 mg dose of propranolol was greater than that of a 200 mg dose of prizidilol but both drugs caused persistent beta-adrenoceptor blockade for at least 7 h after ingestion.

Treatment of paroxysmal nodal tachycardia by dual demand pacemaker in the coronary sinus

A patient with refractory paroxysmal atrioventricular nodal re-entrant tachycardia had required direct current cardioversion to terminate attacks on 83 occasions. A dual demand pacemaker was implanted to sense and interrupt attacks of tachycardia automatically. The pacing electrode was positioned in the proximal coronary sinus near to the atrioventricular node; a site from which fixed rate underdrive pacing successfully interrupted attacks throughout a trial period of one week, with a lead left in this position on a temporary basis. Complete control of the arrhythmia was obtained in the six months after pacemaker implantation.

Dual-demand pacing for refractory atrioventricular re-entry tachycardia

An automatic dual-demand pacemaker has been used in six patients to treat refractory attacks of paroxysmal re-entry atrioventricular tachycardia that occurred in the Wolff-Parkinson-White syndrome. The pacemaker was designed to pace at a fixed rate of 70 beats per minute when sensed heart rates were either below this rate or above 150 beats per minute; in the latter case, it would compete with the paroxysmal tachycardia and interrupt it after a short period of random scaning. The best location for the permanent pacing electrode and the feasibility of using the pacemaker were tested in each case during a detailed preliminary intracardiac electrophysiological study. The permanent pacing electrode was positioned in the coronary sinus in three patients and was attached to the epicardium of either the left or right ventricle in another three. All patients were given regular oral doses of verapamil or propranolol to enhance the effectiveness of the pacemaker system and, with the latter, to prevent pacemaker activation during sinus tachycardia. Over a follow-up period of between 11 and 47 months, the pacemaker system remained completely effective in three patients, but developed unreliable sensing in another two (one coronary sinus and one left ventricular lead). In the sixth patient the pacemaker was only effective when the rate of the tachycardia remained below 170 beats a minute, as when she was resting supine; when sitting or standing, however, her tachycardia rate considerably exceeded this value and the pacemaker was ineffective. Explantation of the pacemaker and either successful cryosurgical ablation of the accesory AV pathway or treatment with amiodarone was undertaken in the three patients in whom the pacemaker had failed.

Wolff-Parkinson-White syndrome (type A) complicated by heart block in both normal and accessory pathways

A 67-year-old man with Wolff-Parkinson-White syndrome type A presented with second degree atrioventricular block in anomalous pathway and complete infra-Hisian block in the His-Purkinje pathway. He had increasingly frequent attacks of dizziness not related to exercise. A permanent ventricular demand pacemaker was successfully implanted following intracardiac electrophysiological studies.

Single lead for permanent physiological cardiac pacing

A method of achieving permanent pacing by the use of a single bipolar transvenous lead is described, the atrial and ventricular electrodes being located on the same lead 14--17 cm apart. The new leads have been implanted successfully in two patients.

The relationship between posture, blood pressure and electrophysiological properties in patients with paroxysmal supraventricular tachycardia

In 9 patients with paroxysmal supraventricular tachycardia the effects of tilting the body on the blood pressure and on responses during tachycardia or pacing revealed important effects that could influence the clinical presentation and the treatment required. Assessment of these reflex responses adds a major dimension to the understanding of the patient with supraventricular tachycardia.

Paroxysmal reciprocating sinus tachycardia

We present clinical and electrophysiological data on 9 patients with paroxysmal reciprocating sinus tachycardia (PRST) of whom only 6 described palpitations. Sinus node disease was present in 5 and cardiac ischemia and/or hypertension in another 3; the remaining case had apparently coincidental Wolff-Parkinson-White (WPW) syndrome. PRST could be initiated in all cases, and terminated in the 4 in whom it was sustained, by suitably timed atrial premature beats over a zone that was dependent on the effective atrial extrastimulus coupling interval (A1-A2) in the high right atrium (HRA). The sequence of atrial depolarization during PRST was similar to that of sinus beats although minor changes in both the P wave and the configuration of the HRA electrogram were observed in half the cases. During paroxysms, cycle length variation and sensitivity to alterations in vagal tone were common. In 6, paroxysms could be initiated by moderately rapid atrial pacing. Repetitive attacks were usually initiated by increases in the sinus rate and not be an antecedent premature atrial extrasystole. Verapamil suppressed sinus node reentry in 5 patients while small doses of atropine favored initiation in 3. PRST was seen in association with AV reentry tachycardias in the patient who had the WPW syndrome.

A spectrofluorometric method for the determination of ajmaline in plasma

1 Ajmaline was found to have maximum fluorescence at neutral pH with 300 nm excitation and 365 nm emission wavelengths (corrected). 2 The fluorescence intensity had a linear relationship to concentration up to 50 microgram ml-1 and the recovery of ajmaline after extraction from plasma was 92.5 +/- 3%. 3 Extraction of drug-free plasma and of samples containing known concentrations of ajmaline showed that drug levels in the range found clinically could be measured accurately by fluorimetry. 4 Serial plasma ajmaline concentrations were measured in a subject after intravenous injection of ajmaline (50 mg). The rates of plasma clearance of the drug were found to be similar to those obtained in previous studies.

Torsade De Pointes, an atypical ventricular tachycardia

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"Torsade de pointes" initiated by electrical ventricular stimulation

Four cases are described in which electrical stimulation of the right ventricle produced the ventricular arrhythmia known as "torsade de pointes". This arrhythmia has previously been described as classically occurring in the context of the chronic bradycardias, particularly when there is also hypokalemia and a long QT interval, being most frequently initiated by a ventricular extrasystole occurring relatively late during ventricular repolarization. One patient had suffered a recent anterior myocardial infarction and developed the arrhythmia during rapid pacing for atrial flutter, when the electrode catheter had inadvertently entered the right ventricle. In the other three patients the arrhythmia was produced during the ventricular extrastimulus test performed during routine diagnostic electrophysiological investigation.

Retroperitoneal haemorrhage and neuropathy complicating anticoagulant therapy

Nine cases of retroperitoneal haemorrhage complicating anticoagulant therapy are reported. Six cases were receiving heparin for myocardial infarction: an incidence of 4·3% of patients on such treatment. All the cases presented with pain, six had neurological involvement and one patient died.

The incidence of this complication is higher than previously noted. Retroperitoneal haemorrhage requires a high index of clinical suspicion for early diagnosis and treatment if serious sequaelae are to be prevented.