Supraventricular Premature Complexes Research Articles

ORAL PRESENTATION

ORAL PRESENTATION

Comprehensive arrhythmia analysis in telemetered non-human primates

The purpose of this study was to determine the normal frequency of arrhythmias in a colony of telemetered cynomolgus monkeys, since there is a data gap in background arrhythmias in this species. To conduct this analysis, continuous ECG data (24 hr) were recorded from 18 telemetry-instrumented monkeys on 3 separate days, over an 8 day period. For each animal, an arrhythmia waveform library was manually created, then applied to the waveform file using EMKA ecgAuto, a pattern recognition-based software application. On day 1, 8/18 monkeys showed at least 1 premature ventricular contraction (PVC; range: 1-12), with 2/18 showing 1 incidence of supraventricular premature complexes (SPC). On day 4, a similar pattern emerged: 5/18 monkeys showed at least 1 PVC (range: 1-12) and 3/18 had 1 incidence of SPC. On day 8, 7/18 NHP displayed at least 1 PVC and 1/18 had a SPC. Other arrhythmias were noted sporadically: right bundle branch block, wandering pacemaker, SA node pause. The pattern of arrhythmia was relatively consistent in each NHP.

Cardiac arrhythmias in clinically healthy showjumping horses

Electrocardiographic reference values of clinically normal horses during exercise are a prerequisite when evaluating horses with poor performance or horses presented with cardiac abnormalities (e.g. valvular regurgitation). No published studies have reported cardiac rhythms of clinically normal showjumping horses. To demonstrate the feasibility of obtaining exercise electrocardiogram (ECG) in normal horses during showjumping and also to document the prevalence and frequency of arrhythmias in association with exercise. Thirty-four healthy showjumping horses aged 4-13 years (mean 7.5 years) underwent clinical examination and resting echocardiography. Modified chest lead ECG examinations were performed during rest, during a standardised showjumping course, as well as for the following 45 min recovery. All ECG recordings were analysed for presence and frequency of arrhythmias. Six horses (17%) were excluded due to ECG recordings of poor diagnostic quality. Echocardiography demonstrated that 11 (39%) horses had one or more mild or moderate valvular regurgitations, but no associations were found between valvular regurgitation and arrhythmias. Supraventricular premature complexes (SVPCs) were found in 9 (32%) horses at rest, 25 (89%) during exercise and 15 (54%) during recovery. Only few arrhythmias occurred in each horse (<9 SVPCs/horse); however, one horse had 13 single SVPCs during exercise and another developed 41 SVPCs during recovery. SVPCs occurred typically at low HR (40-98 beats/min). Ventricular premature complexes (VPCs) was demonstrated in 5 (18%) horses during exercise and 2 (7%) during recovery, with <2 VPCs/horse. It is possible to obtain good quality ECG during showjumping. Reference values for normal performing showjumping horses are presented for the first time and showed a high prevalence of SVPCs both during and after exercise, but few VPCs. Normal reference values enable future studies of cardiac function in showjumping horses presented with poor performance and provide valuable information for veterinary practitioners in the field.

Prevalence of exercise‐associated arrhythmias in normal performing dressage horses

Exercise-associated arrhythmias are important differentials when evaluating poor performance sport horses. However, most studies of arrhythmias have been conducted in racehorses and therefore there is a paucity of knowledge concerning the prevalence and significance of exercise-associated arrhythmias in riding horses. The objective of this study was to examine the prevalence of arrhythmias, particularly supraventricular premature complex (SVPCs) and ventricular premature complex (VPCs), associated with exercise in normal performing dressage horses. In total, 21 normal performing dressage horses, aged 5-16 years (mean 9 years), were examined clinically and echocardiographically to detect the prevalence of valvular regurgitation. Electrocardiographic (ECG) examinations were performed during rest and during a standardised dressage exercise programme, as well as during recovery period 1 h after exercise. All ECG recordings were analysed for presence and frequency of arrhythmias and arrhythmias were correlated with HR. Mean HR for walk, trot, canter and for specific dressage movements, as well as maximum HR was calculated. Fisher's exact test was used to test for associations between arrhythmias, valvular regurgitation, age and gender. SVPCs occurred rarely during rest, but occurred during exercise in 6 (28.6%), and in 13 (61.9%) horses during recovery period. Most horses had ≤ 3 SVPCs. Ventricular premature complex were seen in one horse, which developed twice during exercise. Mild valvular regurgitation was seen in 11 (52%) of the horses. No significant associations between arrhythmia and age, gender or valvular regurgitation were observed. Reference values for normal performing dressage horses are presented for the first time, demonstrating that arrhythmias occur infrequently during exercise and recovery. Maximum HR in dressage horses is low compared to both showjumping and racehorses. Studies of dressage horses with moderate to severe valvular regurgitation at rest or poor performance are needed to further elucidate the significance of cardiac arrhythmias.

Correlation of heart rate to body weight in apparently normal dogs

Objective To evaluate the correlation between heart rate and body weight in the apparently healthy dog. Animals Sixty dogs weighing between 2 and 80 kg. Methods Heart rate was evaluated with a 24-h ambulatory electrocardiogram. Minimum, average, maximum heart rate, ventricular premature complex (VPC) number and supraventricular premature complex (SVC) number were tabulated for each dog. Results Minimum, maximum and average heart rate did not correlate to body weight. For all dogs, the median minimum heart rate was 42 bpm (beats per minute), median average heart rate was 73 bpm, and median maximum heart rate was 190. The median number of VPCs and SVC was zero. Conclusions The present study does not support a correlation between heart rate and body weight in apparently healthy dogs.

Hypoxia and cardiac arrhythmias in breath-hold divers during voluntary immersed breath-holds

The incidence and nature of cardiac arrhythmias during static apnea were studied by monitoring the electrocardiogram (ECG) and oxygen saturation (SaO(2)) of 16 recreational breath-hold divers. All subjects completed a maximal apnea with a mean (+/-SD) breath-hold duration of 281 (+/-73) s without clinical complications. Both heart rate (HR) and SaO(2) decreased significantly with breath-hold duration. The decline in SaO(2) was inversely related to the decline in HR (r = -0.55, P < 0.05). Cardiac arrhythmias (supraventricular and ventricular premature complexes, right bundle branch block) occurred in 12/16 (77%) subjects and were related to breath-hold duration. Subjects with atrial premature complexes (n = 9) had a reduced BMI (P = 0.016) and a higher decline of the terminal SaO(2) (P = 0.01). In conclusion, ectopic arrhythmias were common during maximal static apneas for training purposes. The results indicate that the occurrence of ectopic beats is associated with individual factors such as the tolerable SaO(2) decrease.

Disritmias cardíacas e alterações do segmento ST em idosos no perioperatório de ressecção transuretral da próstata sob raquianestesia: estudo comparativo

Elderly account for 25% of surgical patients. Several patients with arterial heart disease have normal preoperative ECG and a high incidence of silent myocardial acute infarction in the first postoperative week. Arrhythmias increase with age and supraventricular and ventricular premature complexes, atrial fibrillation and intraventricular conduction abnormalities are observed. This study aimed at evaluating the prevalence of perioperative arrhythmias and ST changes through Holter System in elderly patients submitted to transurethral prostatectomy and inguinal hernia repair under spinal anesthesia.Participated in this study 21 patients aged 65 to 84 years submitted to transurethral prostatectomy (TUP) and 16 patients aged 63 to 86 years submitted to inguinal hernia repair under spinal anesthesia. Monitoring with Holter System was performed in the preoperative (12 hours), intraoperative (3 hours) and postoperative (12 hours) periods.The prevalence of supraventricular premature complex was 85.7% vs. 93.7% in the preoperative period, 85.7% vs. 81.2% in the intraoperative and 76.2% vs. 100% in the postoperative period, respectively for groups TUP and control. The prevalence of ventricular premature complex was 76.2% vs. 81.2% in the preoperative period, 80.9% vs. 68.7% in the intraoperative period, and 80.9% vs. 81.2% in the postoperative period, respectively for groups TUP and control. The prevalence of ST changes was 19% vs. 18.7% in the preoperative period, 4.7% vs. 18.7% in the in the intraoperative period, and 14.3% vs. 18.7% in the postoperative period between groups TUP and control, without statistical significance.Elderly patients have a high prevalence of supraventricular and ventricular cardiac arrhythmias. The total number of preoperative arrhythmias and ST changes was not changed as a function of transurethral prostatectomy surgery or inguinal hernia repair, in the intra and postoperative periods.

The effects of ephedrine on intramuscular blood flow and other cardiopulmonary parameters in halothane-anesthetized ponies

ObjectiveTo evaluate the effect of ephedrine on intramuscular blood flow and hemodynamic parameters during equine anesthesia. Study designProspective experimental study. AnimalsSix healthy adult Welsh Mountain ponies (five males, one female, mean weight: 267 kg, range: 213–347 kg). MethodsHalothane-anesthetized ponies received an IV bolus of ephedrine (0.1 mg kg−1), followed 30 minutes later by a second IV ephedrine injection (0.2 mg kg−1). Changes in intramuscular blood flows (IMBF) in upper and lower triceps brachii were measured by laser Doppler flowmetry. Cardiopulmonary measurements were made at intervals for 30 minutes following each injection. Results were compared with values from a control group, similarly anesthetized but given saline in an earlier study. ResultsEphedrine at either dose increased heart rate, arterial blood pressure (AP), cardiac index (CI) and intramuscular blood flow (IMBF), the effects on these parameters being significant and long-lasting following the higher dose. Systemic vascular resistance remained unchanged, and was significantly lower than in the control saline group. PaO2 decreased significantly immediately following the first injection of ephedrine, then remained unchanged for the remainder of the experiment. PaCO2 increased slowly throughout the anesthetic period. One pony developed supraventricular premature complexes following the second injection. No other side effects were seen. ConclusionEphedrine at dose rates of 0.2 mg kg−1 IV consistently increased in CI, AP, and IMBF in both forelimbs. Clinical relevanceEphedrine may be of use to improve AP, CI and IMBF during halothane anesthesia, although the occurrence of an arrhythmia in one pony is of concern.

Short-term Cardiovascular Effects of Salmeterol

The occurrence of cardiovascular side effects is sometimes associated with the utilization of beta-adrenoceptor agonists. The most important causes of these undesirable pharmacologic actions are as follows: (1) direct stimulation of cardiac beta-adrenoceptors; (2) reflex activation of adrenergic mechanisms due to peripheral vasodilation; (3) hypokalemia; and (4) hypoxemia. The aim of this study was to evaluate the potential short-term, cardiovascular side effects of salmeterol, a long-acting and highly selective beta2-adrenoceptor agonist. Eight volunteer healthy subjects and eight patients with reversible airway obstruction and without cardiovascular alterations were treated with 50 microg of salmeterol twice a day for 3 days and then with 100 microg of salmeterol twice a day for a further 3-day period. The 24-h ECG (Holter) monitoring and measurement of arterial BP, performed on the admission day and on the third and the sixth day of pharmacologic treatment, showed that salmeterol did not produce any significant change in mean heart rate, number of supraventricular and ventricular premature complexes, and BP. Furthermore, no ECG abnormality related to myocardial ischemia was recorded during 24-h Holter monitoring. These data suggest that salmeterol, administered in regular and high doses for a short period, does not cause significant cardiovascular effects in both normal subjects and patients with reversible airway obstruction.

Doppler echocardiographic patterns in patients with acromegaly

Cardiovascular problems have long been recognized as responsible for an increased morbidity and mortality in patients with acromegaly. The aim of the present study was to evaluate echocardiographically the prevalence of cardiomyopathy in a cohort of acromegalic patients and to analyze the results in relation to demographic, clinical and hormonal data. This study, a retrospective controlled clinical trial, was performed in 25 acromegalic patients, 12 men and 13 women aged 26-66 years (mean: 52.6). Fifteen patients had an active disease, 10 were cured by previous pituitary surgery. The same echocardiographic parameters were analyzed in 50 healthy subjects aged 30-70 years (mean: 51.4). Serum GH was determined on at least 4 samples drawn over 24 hours and plasma IGF-I on a single point. Standardized parameters of diastolic and systolic function were evaluated by real-time Doppler echocardiography. Twelve patients with active acromegaly underwent also 48-hour ECG registering. Left ventricular (LV) hypertrophy was found in 14/25 patients (56%). No difference was found between patients with active disease (53%) and patients with cured acromegaly (60%). LV mass index was significantly increased in acromegalics in comparison with healthy subjects (137 +/- 43 g/m2 vs 96 +/- 16 g/m2, p < 0.01) and also the indices of LV diastolic function were significantly impaired. Asymmetric septal hypertrophy was found only in one patient. Hypertension was detected in 9/25 patients (36%) without difference between patients with active or cured disease (40% vs 30%, NS). No significant correlation was found between hormonal or clinical data and echocardiographic findings. During Holter monitoring, heart rate of acromegalics was not significantly different from that of controls (78 +/- 12 bpm vs 72 +/- 10 bpm, NS) and only isolated supraventricular or ventricular premature complexes (Lown class 1) were detected. In conclusion, this study provides evidence of subclinical LV dysfunction in acromegaly in the absence of other known causes of heart disease and no significant difference in echocardiographic pattern was apparent between active or cured acromegalics.

Electrocardiographic changes following rabbit coronavirus-induced myocarditis and dilated cardiomyopathy.

Rabbit Coronavirus (RbCV) infection was divided into two phases based upon day of death and pathologic findings. During the acute phase (days 2-5) heart weights (HW) and heart weight-to-body weight (HW/BW) ratios were increased with striking dilation of the right ventricle. These changes as well as increased dilation of the left ventricle were especially pronounced during the subacute phase (days 6-12). Myocytolysis, pulmonary edema, and degeneration and necrosis of myocytes, were seen during both phases. Myocarditis, pleural effusion, calcification of myocytes, and congestion in the liver and lungs were seen in the subacute phase. Electrocardiograms (ECGs) exhibited low voltage, nonspecific ST-T wave changes, sinus tachycardia, occasional ventricular and supraventricular premature complexes and 2(0) AV block consistent with myocarditis and heart failure. Forty-one percent of the survivors exhibited increased HW and HW/BW ratios, biventricular dilation, interstitial and replacement fibrosis, myocyte hypertrophy and myocarditis. ECGs exhibited nonspecific ST-T wave changes, sinus arrhythmia, occasional ventricular and supraventricular premature complexes and 2(0) AV block. These data suggest that RbCV infection may result in viral myocarditis and heart failure with a proportion of survivors progressing into DCM.

Electrocardiographic changes and arrhythmias after cancer therapy in children and young adults

Transient electrocardiographic changes and arrhythmias are known to be acute manifestations of cardiotoxcity secondary to cancer therapy with anthracyclines or cardiac irradiation. However, despite the known risk of late cardiac dysfunction in survivors of childhood cancer therapy, the risk of clinically important electrocardiographic abnormalities and arrhythmias after treatment is unknown. Standard 12-lead and 24-hour ambulatory electrocardiograms were recorded in 73 patients who received anthracyclines atone, 24 who received cardiac irradiation alone, and 27 who received both anthracyclines and cardiac irradiation. The mean age of the patients was 15 years. Mean cumulative anthracycline dose was 282 mg/m 2 in patients who received anthracyclines alone and 244 mg/m 2 in patients who received both anthracyclines and cardiac irradiation. Analysis of the 12-lead and 24-hour electrocardiograms demonstrated increased frequency of QTc prolongation, supraventricular premature complexes, supraventricular tachycardia, ventricular premature complexes, couplets and ventricular tachycardia (all p < 0.001) when compared with an age-matched healthy population. Most patients had abnormalities limited to single supraventricular or ventricular premature complexes; however, potentially serious ventricular ectopy, including ventricular pairs and ventricular tachycardia, were noted in patients with cumulative doses > 200 mg/m 2. Electrocardiographic abnormalities and arrhythmias are not limited to the acute phase of treatment with anthracyclines and cardiac irradiation. Survivors of childhood malignancy who received anthracyclines or cardiac irradiation, or both, probably should undergo ambulatory electrocardiographic monitoring as part of their follow-up to detect potentially life-threatening arrhythmias.

Relation of endocrine and cardiac findings in acromegalics.

Cardiac involvement in 32 acromegalics was related to endocrine parameters, clinical score and duration of the disease as well as compared to that of 50 controls free of cardiac disease. Stress ECG, 24h Holter monitoring and echocardiography revealed that supraventricular premature complexes did not occur more often in acromegalics than in controls, both prevalence and severity of ventricular arrhythmia, however, were higher in patients compared to controls: 15/32 (48%) acromegalics had complex ventricular arrhythmia as compared with 6/50 (12%) normal subjects (p less than 0.01). Repetitive ventricular arrhythmia was manifest in 10/32 (31%) patients but only in 4/50 (8%) controls (p less than 0.01). Furthermore, frequency of ventricular premature complexes increased with duration of acromegaly (p less than 0.01), the severity of the former being correlated with left ventricular mass and with clinical activity score (p less than 0.01). No correlation, however, was found between the degree of ventricular arrhythmia and hormone levels. Left ventricular muscle mass was increased (p less than 0.02) due to concentric hypertrophy. Thus, compared to controls, acromegalics show more frequent and complex ventricular arrhythmia and left ventricular hypertrophy. Duration of the disease rather than hormone levels seems to be relevant for these pathological changes.

Arrhythmia profile in acromegaly.

In a controlled study, the cardiac involvement and arrhythmia profile of 32 patients with acromegaly were correlated with endocrine parameters (somatomedine C, growth hormone), clinical score and duration of the disease. Data were compared with those of 50 controls free of cardiac disease. Stress ECG, 24 h Holter monitoring and echocardiography were performed. Supraventricular premature complexes occurred no more often in acromegalics than in controls. Both prevalence and severity of ventricular arrhythmia, however, were significantly higher in patients compared to controls (P less than 0.01). 15/32 (48%) acromegalic patients had complex ventricular arrhythmias (Lown III-IV) as compared with 6/50 (12%) normal subjects (P less than 0.01). Repetitive ventricular arrhythmias (Lown IV a/b) occurred in 10/32 (31%) patients, but only in 4/50 (8%) controls (P less than 0.01). Furthermore, the frequency of ventricular premature complexes increased with duration of acromegaly (P less than 0.01). No correlation was found between the severity of ventricular arrhythmia and hormone levels. Left ventricular muscle mass was significantly increased (285 +/- 139 g, P less than 0.02) due to concentric hypertrophy. Severity of ventricular arrhythmias correlated with left ventricular mass and with clinical activity score (P less than 0.01). Thus, compared to controls, acromegalic patients show more frequent and complex ventricular arrhythmias and left ventricular hypertrophy. Duration of the disease rather than hormone levels seems to be relevant for these pathological changes.

Cardiac arrhythmias and heart rate in hyperthyroidism

The arrhythmia profile and heart rate (HR) were analyzed by 24-hour Holter monitoring in 37 hyperthyroid patients before (triiodothyronine [T 3] hormone level = 331 ± 108 ng/dl), during (T 3 level = 202 ± 98 ng/dl) and after an antihyperthyroid therapy of 8 to 89 weeks' duration (T 3 level = 149 ± 41 ng/dl). The data were compared with those of 50 control subjects free from cardiac disease. Only 12 hyperthyroid patients (32%) had complex ventricular arrhythmias (Lown grade 3 or 4) as compared with 6 normal subjects (12%, p > 0.05). Three patients (8%) had repetitive ventricular arrhythmias (Lown grade 4A/B) as compared with 4 normal subjects (8%, p > 0.05). Supraventricular premature complexes occurred more often in hyperthyroid patients than in normal subjects before and after therapy (P < 0.001). The prevalence of supraventricular tachycardia decreased from 8 patients to 1 during therapy (p < 0.002). The HR decreased from 95 ± 13 to 79 ± 9 beats/min after therapy, but was still increased as compared with the normal subjects (72 ± 8 beats/min, p < 0.001). A day/night difference in HR > 10% was found in 32 patients (86%) and was more pronounced than in the normal group (p < 0.001). Compared with the normal HR profile, the HR curve of hyperthyroid patients was shifted to a higher level (about 20 beats/min). Serum T 3 level correlated best with HR at night in hyperthyroid patients (r = 0.74, p < 0.001). Thus, hyperthyroid patients show frequent supraventricular arrhythmias that might be reversible during therapy. However, ventricular arrhythmias are infrequent and remain essentially unchanged during therapy. The hyperthyroid state increases HR in general, but day/night differences in HR remain unchanged.

Exercise-induced arrhythmias in diuretic-treated patients with uncomplicated systemic hypertension

Although hypertensioe patients have been shown to have a higher prevalence of arrhythmias during ambulatory monitoring when treated with diuretic drugs than when untreated, the effects of maximal aerobic stress on arrhythmia frequency in such patients is unknown. The incidence of arrhythmias during graded maximal treadmill exercise in a group of 68 subjects with mild, clinically uncomplicated systemic hypertension treated chronically with diuretics alone for a median of 4.5 years was compared with that in an age-matched normotensive control group. The prevalence of exercise-induced arrhythmias was higher in the group treated with diuretics, than in the control group, 57% vs 38% (p <0.05) This difference was entirely due to the higher incidence of isolated atrial or ventricular premature complexes in the diuretic-treated patients, 44% vs 26% (p <0.05). There was no difference in the incidence of frequent (more than 10% of beats) or complex supraventricular or ventricular premature complexes between the diuretic-treated and control groups. Within the diuretic group, no difference in the incidence of simple or complex arrhythmia was found between men and women, between those with and those without rest or exercise-induced electrocardiographic abnormalities or between those with a serum potassium level of less than 3.7 mEq/liter vs those with a level of 3.7 mEq/liter or greater. Thus, patients with uncomplicated hypertension treated with chronic diuretic monotherapy do not appear to be at increased risk for major arrhythmias during aerobic exercise.

Holter detection of cardiac arrhythmias in intracranial subarachnoid hemorrhage

To determine the frequency and severity of cardiac arrhythmias in intracranial Subarachnoid hemorrhage, 120 nonselected patients were prospectively studied by 24-hour Holter monitoring. Arrhythmias were found In 96 of 107 patients (90%) with adequate Holter recording: ventricular premature complexes in 49, nonsustained ventricular tachycardia in 5, supraventricular premature complexes in 29, paroxysmal supraventricular tachycardia or atrial fibrillation in 9, sinoatrial block and arrest in 29, second-degree atrioventricular block in 1, atrioventricular dissociation in 4 and idioventricular rhythm in 2. Life-threatening ventricular arrhythmias (torsades de pointes-type ventricular tachycardia) occurred in 4 patients, degenerating into either ventricular flutter or fibrillation in 2. ST-segment changes suggestive of acute transitory myocardial ischemia were found in 8 patients (1.5 mm or more of ST depression in 7 patients and 1.5 mm or more of ST elevation in 1 patient). The frequency and severity of arrhythmias were significantly higher in patients studied within 48 hours of Subarachnoid hemorrhage; serious ventricular arrhythmias were associated with QTc prolongation more than 550 ms and with hypokalemia less than 3.5 mEq/liter. No correlation was found between age, clinical condition, site and extent of subarachnoid hemorrhage and either the occurrence or severity of arrhythmias. The results of our study indicate an extremely high incidence of arrhythmias, sometimes serious, in subarachnold hemorrhage, especially in the first 48 hours after hemorrhage. Continuous electrocardiographic monitoring is therefore mandatory.

Antiarrhythmic effect of the calcium antagonist tiapamil (Ro 11-1781) by intravenous administration in patients with coronary heart disease.

Twenty coronary patients with a median age of 76 years were treated in the coronary care unit with tiapamil, a new Ca2+ antagonist, by intravenous infusion (until December, 1979, the generic name was dimeditiapramine). The following arrhythmias were identified: atrial fibrillation with ventricular rate greater than 95 beats/min (5 patients); supraventricular premature complexes (SVPC) (4 patients); and ventricular premature complexes (VPC), Lown grades 2-4 (15 patients). Electrocardiograms and hemodynamic parameters were continuously monitored prior to, during, and after the therapy. In patients with atrial fibrillation, sinus rhythm was not restored, but tiapamil decreased the ventricular rate by 54%. In patients with VPC, the median frequency of VPC decreased from 310.5 before tiapamil to 32.5 beats/h at the fourth hour of therapy (p less than 0.01). The median ectopic/sinus beat ratio decreased from 0.083 (pretreatment) to 0.008 at the fourth hour of infusion (p less than 0.10). In one of the patient with an insufficient decrease in the number of VPC, the VPOC changed from class 4a (pretreatment) to class 2 (during the therapy), returning to class 4a after the infusion was stopped. Tiapamil reduced the median systolic and diastolic blood pressures by 8.3 and 7.1%, respectively (p less than 0.05), the third hour. Hypotension and bradycardia were observed in 5/20 patients. The results show that tiapamil is effective against both supraventricular and ventricular arrhythmias, and thus its spectrum of action differs from that of other calcium antagonists.

Antiarrhythmic effect of the calcium antagonist tiapamil (ro 11-1781) by intravenous administration in patients with coronary heart disease

Twenty coronary patients with a median age of 76 years were treated in the coronary care unit with tiapamil, a new Ca2+ antagonist, by intravenous infusion (until December, 1979, the generic name was dimeditiapramine). The following arrhythmias were identified: atrial fibrillation with ventricular rate >95 beats/min (5 patients); supraventricular premature complexes (SVPC) (4 patients); and ventricular premature complexes (VPC), Lown grades 2–4 (15 patients). Electrocardiograms and hemodynamic parameters were continuously monitored prior to, during, and after the therapy. In patients with atrial fibrillation, sinus rhythm was not restored, but tiapamil decreased the ventricular rate by 54%. In patients with VPC, the median frequency of VPC decreased from 310.5 before tiapamil to 32.5 beats/h at the fourth hour of therapy (p<0.01). The median ectopic/sinus beat ratio decreased from 0.083 (pretreatment) to 0.008 at the fourth hour of infusion (p<0.10). In one of the patients with an insufficient decrease in the number of VPC, the VPC changed from class 4a (pretreatment) to class 2 (during the therapy), returning to class 4a after the infusion was stopped. Tiapamil reduced the median systolic and diastolic blood pressures by 8.3 and 7.1%, respectively (p<0.05), the third hour. Hypotension and bradycardia were observed in 5/20 patients. The results show that tiapamil is effective against both supraventricular and ventricular arrhythmias, and thus its spectrum of action differs from that of other calcium antagonists.

Maximal exercise stress testing in evaluation of arrhythmias in children: Results and reproducibility

To assess reproducibility in evaluating arrhythmias in children, two maximal treadmill exercise tests using the Bruce protocol were performed an average of 3.1 months apart in 19 children aged 5 to 16 years (mean 11) with chronic idiopathic ventricular (Group 1) and supraventrlcular (Group II) arrhythmias. The performance of each child during the two tests was not statistically different with regard to maximal heart rate achieved or duration of exertion; all but one child achieved expected maximal heart rates. in Group I, eight of nine children with ventricular premature complexes at rest showed suppression of the arrythmia during exercise at similar heart rates on both tests. In one child, ventricular premature complexes were not diminished in either test. One child with accelerated idioventricular rhythm and one with ventricular parasystole had reproducible arrhythmia suppression during exercise. One child with known episodes of ventricular tachycardia had this arrhythmia induced by exercise on both tests. In Group II, five children with supraventricular or junctional premature complexes at rest showed reproducible arrhythmia suppression on exercise, but one unexpectedly manifested ventricular premature complexes and one manifested runs of ectopic atrial rhythm during both exercise periods. Two children with severe sinus bradycardia achieved expected maximal heart rates. One unexpectedly manifested reproducible supraventricular premature complexes after exercise. Comparison of results of exercise testing with ambulatory electrocardiographic monitoring showed that in four patients testing uncovered arrhythmias not evident on monitoring, whereas in one patient severe sinus bradycardia occurred only during monitoring. These results indicate that maximal treadmill exercise for evaluation of arrhythmias can be performed in children using standard methodology and can yield important data reproducibly.