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Biomedical subjects

S Laniado

Publications and source records attributed to S Laniado.

At least 127 records · Page 7Linked to original sources
PubMed1985

Clinical and hemodynamic effects of combined propranolol and nifedipine therapy versus propranolol alone in patients with angina pectoris.

To determine the comparative effectiveness and hemodynamic effects of long-term oral treatment with propranolol alone and combined with nifedipine in patients with stable angina pectoris, 20 patients with coronary disease were studied by equilibrium radionuclide ventriculography. Measurements were performed at rest and during supine bicycle exercise before treatment, after 4 weeks on propranolol, 1 hour after institution of combined propranolol and nifedipine treatment, and after 4 weeks on the combined treatment. The reduction in exercise rate-pressure product induced by the combination (17.2 +/- 2.6 X 10(3)) was significantly greater (p less than 0.001) than that attained by propranolol alone (19.3 +/- 2.8 X 10(3)). In patients at rest, neither propranolol nor the combined therapy altered global left ventricular (LV) ejection fraction (EF). Without drugs and on propranolol, exercise EF decreased significantly. On the combined therapy there was a significant improvement in exercise EF compared both with rest values (p less than 0.01) and with exercise EF on propranolol (p less than 0.001). Exercise tolerance, expressed as total work load, significantly increased on propranolol and further increased on combined therapy. Thus the combined propranolol/nifedipine therapy in patients with stable angina proved to be hemodynamically superior to therapy with propranolol alone and safe even in patients with moderately depressed LV function.

Administration, Oral↗
PubMed1985

Pharmacokinetic differences between peripheral and central drug administration during cardiopulmonary resuscitation.

Advanced resuscitation techniques are dependent on drug therapy to increase survival. Because drugs must reach their site of action instantaneously, the choice of appropriate route of administration may be critical. To study the pharmacokinetics of drug administration by peripheral and central venous routes during resuscitation, nine mongrel dogs were studied. Arterial blood pressure and electrocardiograms were monitored continuously. Cardiac output was evaluated before resuscitation to determine control levels. After thoracotomy and fibrillation of the heart, cardiac massage was started with a frequency of compression maintained at 60/min. Bolus injections of two different radioisotopes were given simultaneously through a peripheral and a central vein. Isotope activity was sampled through a catheter in the right femoral artery at 5 second intervals for 90 seconds and at 30 second intervals for 210 seconds. The major differences between the two routes of administration were that central injection produced a 270% higher peak concentration (p less than 0.001) and significantly shorter lag times to the first appearance of tracer (16 +/- 7 versus 38 +/- 13 seconds, p less than 0.05) and times to peak concentration (13 +/- 5 versus 27 +/- 12 seconds, p less than 0.01). In contrast, there were no significant differences in area under the time-counts curve, mean residence time, total body clearance and steady state volume of distribution. The central compartment volume of distribution was significantly smaller after central than after peripheral injection (26.1 +/- 56 versus 76.3 +/- 16.5 ml, p less than 0.01). The therapeutic implications of these findings must be investigated for individual drugs used during cardiorespiratory resuscitation to determine the most appropriate route and dosage for each agent.

Animals↗
PubMed1985

Clinical significance of nonclinical ventricular tachycardia induced in amiodarone-treated patients.

The clinical significance of sustained nonclinical ventricular tachycardia (VT) induced during electrophysiologic studies was studied in 10 amiodarone-treated patients. Nine patients had previous myocardial infarction while 1 patient had right ventricular dysplasia. All patients had only a single morphologic type of VT recorded during the multiple spontaneous episodes of tachycardia. After serial pharmacological electrophysiologic testing, the patients were placed on antiarrhythmic regimens which included amiodarone in all cases. These drugs did not prevent the induction of nonclinical VT in any of the 10 patients and of sustained clinical VT in 7 patients. Nonclinical VT was sustained, requiring cardioversion (7 patients) or rapid ventricular pacing (3 patients) for termination. After a mean follow-up period of 27 +/- 10 months (range 12 to 36 months), 4 patients did not exhibit recurrent VT, 3 patients with inducible clinical VT experienced a recurrent episode of clinical VT after 16, 27 and 49 months, respectively, 2 patients had nonarrhythmia related deaths after 11 and 12 months, and 1 patient died suddenly after 17 months. These results suggest that laboratory induction of sustained nonclinical VT in amiodarone-treated patients does not imply the likelihood of their future spontaneous occurrence and, therefore, their prevention may not be required.

Adult↗
PubMed1985

Effects of verapamil and bepridil on occlusion and reperfusion arrhythmias in the canine heart.

The effects of verapamil and bepridil on occlusion and reperfusion ventricular arrhythmias including ventricular fibrillation (VF) were studied in a canine model. The control group consisted of 27 dogs. 30 dogs received intravenous verapamil (0.2 mg/kg/3 min followed by a continuous infusion of 0.01 mg/kg/min for 15 min). 18 dogs received bepridil (0.5 mg/kg/min for 10 min). The left anterior descending coronary artery was occluded in one step 8 min after the commencement of verapamil administration and 5 min after the termination of bepridil infusion. The incidence of ventricular arrhythmias during the occlusion period was 14 (VF, 5/14), 13 (VF, 0/13) and 14 (VF, 9/14) in the control, verapamil and bepridil groups, respectively. The frequencies of reperfusion VF were 8/24 (33%), 4/30 (13.3%) and 0/13 (0%), respectively. It was concluded that (a) verapamil effectively prevents occlusion but not reperfusion VF and (b) bepridil has an arrhythmogenic effect in the ischemic canine heart but reduces the incidence of reperfusion VF.

Animals↗
PubMed1985

Apical hypertrophic cardiomyopathy: evaluation by noninvasive and invasive techniques in 23 patients.

Over a 3 year period we evaluated 23 patients (16 men, seven women) with apical hypertrophic cardiomyopathy by noninvasive and invasive methods. Sixteen patients had chest pain. In 17, results of cardiovascular examination were normal. The electrocardiogram showed precordial inverted T waves in all patients and these were of mild-to-moderate amplitude (less than 10 mm) in 18 and giant (greater than 10 mm) in five. M mode echocardiography revealed a typical pattern of contraction and relaxation in the apical region of the left ventricle that was associated with significant hypertrophy. These findings were confirmed by two-dimensional echocardiography. Systolic anterior motion of the mitral valve was not observed nor was there any evidence of obstruction of the left ventricular outflow tract. Results of Doppler echocardiographic study of the mitral and aortic flow were normal in all patients but one who had mild mitral insufficiency. Radionuclide studies of 14 patients revealed a mean left ventricular ejection fraction of 66 +/- 6% (range 55% to 79%), with normal left ventricular contraction in all patients but two with apical hypokinesis. In all six patients who underwent catheterization a characteristic appearance of the left ventricle at end-systole as well as abnormal end-diastolic contour were noted on the left ventricular angiogram, but the "ace of spades" configuration was seen in only one. We conclude that the 23 patients studied form a homogeneous group of individuals with nonobstructive apical hypertrophic cardiomyopathy, which differs in many respects from cardiomyopathies reported by other investigators.

Adult↗
PubMed1985

Pulmonary venous flow pattern--its relationship to cardiac dynamics. A pulsed Doppler echocardiographic study.

We studied the physiology of pulmonary venous flow in 13 normal subjects and five patients with atrial rhythm disorders and atrioventricular conduction disturbances with pulsed Doppler and two-dimensional echocardiography. The left atrium, mitral valve, and pulmonary venous ostia were visualized through the apical four-chamber view. Mitral and pulmonary venous flows were obtained by placing the Doppler sample volume at the appropriate orifice. Pulmonary venous flow was biphasic: a rapid filling wave was observed during systole when the mitral valve was closed; a second wave was observed in diastole during the rapid ventricular filling phase of mitral flow, but was significantly delayed. In patients without atrial contraction (atrial fibrillation and sinoatrial standstill), the initial rapid filling was greatly diminished and only the second diastolic wave appeared to contribute to left atrial filling. In patients with high-grade atrioventricular block, each atrial contraction was followed by a surge in flow from the pulmonary veins. These results are consistent with data obtained from invasive measurements in both dogs and man, and confirm the validity of the use of pulsed Doppler echocardiography in the study of pulmonary venous flow. We suggest that pulmonary venous flow is influenced by dynamic changes in left atrial pressure created by contraction and relaxation of the atrium and ventricle. The initial peak in pulmonary venous flow occurs with atrial relaxation simultaneously with the reduction of left atrial pressure, and the second peak occurs with left ventricular relaxation and rapid transmitral filling of the ventricle.

Adolescent↗
PubMed1985

Effects of dantrolene sodium on occlusion and reperfusion arrhythmias in the canine heart.

The effects of dantrolene sodium on occlusion and reperfusion ventricular arrhythmias (VA) were studied in a canine model. Transient ischemia was induced by a 10 min occlusion period of the left anterior descending coronary artery in 27 control dogs and 32 dogs pretreated with dantrolene sodium (2.5 mg/kg). In the control group, 14 (52%) dogs experienced VA during occlusion. Five of these had ventricular fibrillation, 3 of which were fatal. Eight of 24 control dogs which reached reperfusion experienced ventricular fibrillation during the first 30 sec of reperfusion. Dantrolene sodium did not lower the frequency of VA during occlusion 22/32 (69%). Moreover, the incidence of fatal ventricular fibrillation during occlusion was significantly (p less than 0.025) higher in the drug treated-group (12/32; 37.5%) than in the control group (3/27; 11%). Dantrolene sodium also significantly reduced the time that lasted from the commencement of occlusion to the appearance of ventricular fibrillation (240 +/- 1 sec versus 166 +/- 9 seconds, control and drug group, respectively p less than 0.05) without significantly altering either heart rate or blood pressure (169 +/- 4 b.p.m., and 170 +/- b.p.m.; 101 +/- 10 mmHg and 104 +/- 9 mmHg, before and after dantrolene sodium, respectively). These results indicate that dantrolene sodium might have an arrhythmogenic effect in the ischemic canine heart.

Animals↗
PubMed1984

Extensive endocardial mapping during sinus rhythm and ventricular tachycardia in a patient with arrhythmogenic right ventricular dysplasia.

A 38 year old man with arrhythmogenic right ventricular dysplasia underwent electrophysiologic study with extensive endocardial mapping of the right ventricle. During sinus rhythm, markedly reduced amplitude with or without prolonged duration was noted in multiple electrograms of the right ventricle. Delayed activation of the right ventricular outflow tract electrogram was present. Two clinical types of ventricular tachycardia with a left bundle branch block configuration and either an inferior or a superior axis were induced by ventricular stimulation. Endocardial activation sequence during the tachycardias suggested that the tachycardia with an inferior axis originated near the infundibulum, while that with a superior axis originated near the midinferior area of the right ventricle. Both areas have been previously shown to be frequently impaired in right ventricular dysplasia.

Adult↗
PubMed1984

Non-invasive recording of His bundle activity in patients with Wolff-Parkinson-White syndrome.

Ten patients with Wolff-Parkinson-White syndrome underwent external His bundle recording using an advanced signal-averaging technique. Surface ECG waveforms were recorded and digitized at 1.28 kHz (10 bit resolution) and then averaged with a CDC-6600 computer. A cross-correlation function, operating in the frequency domain (using the Fast Fourier Transform algorithm) was employed to extract fiducial synchronizing marks for the waveform alignment. Using this technique, reliable His bundle activity could be recorded in nine of ten patients. There was a good correlation between the HQ and HV intervals obtained during external and internal His bundle recordings, respectively, in seven patients who underwent both recordings. Administration of ajmaline enabled to obtain the His bundle activity using a digital filter with low frequency cut-off of 30 Hz as compared to the cut-off of 150 Hz which was necessary during control to reduce the electrical activity of the delta wave. We conclude that using a computerized cross-correlation signal-averaging technique enables the external His bundle recording in patients with WPW syndrome.

Adolescent↗
PubMed1984

Simultaneous AV nodal reentrant and ventricular tachycardias.

Simultaneous AV nodal reentrant and ventricular tachycardias were observed during the course of an electrophysiological study in a 51-year-old patient who suffered from recurrent attacks of sustained ventricular tachycardia. Occurrence of simultaneous tachycardias was facilitated by the fact that both tachycardias had a similar cycle length. Ventricular tachycardia was most probably initiated by AV nodal tachycardia previously induced by atrial extrastimulation following the administration of atropine.

Anti-Arrhythmia Agents↗
PubMed1984

Ventricular tachycardia induced by slow ventricular pacing.

Two patients are described, in whom ventricular pacing at physiological rates (72 to 75 beats/min) repeatedly induced ventricular tachycardia (VT). In the first patient, pacing was required because of complete atrioventricular block following an inferior and right ventricular (RV) myocardial infarction. VT developed during RV posterobasal pacing, but not during RV outflow tract pacing at similar rates. The second patient had a postinfarction left ventricular aneurysm and was paced because of amiodarone-induced sinus node dysfunction. VT developed when the rate of ventricular pacing was similar to that of the sinus rate. We conclude that in patients whom VT is induced at physiological rates of pacing, the following factors may be involved in the triggering of VT: the rate of pacing, the site of ventricular stimulation; and the administration of antiarrhythmic drugs. Early recognition of these factors, which may facilitate reentry by aggravating previously existing intraventricular conduction disturbances, is imperative for the effective management of the arrhythmia.

Aged↗
PubMed1983

Effects of heart rate on experimentally produced mitral regurgitation in dogs.

The effects of increasing heart rate (HR) on the hemodynamics of acute mitral regurgitation (MR) were studied in 8 open-chest dogs. Filling volume, regurgitant volume and stroke volume were calculated from electromagnetic probe measurements of mitral and aortic flows. The left atrial-left ventricular systolic pressure gradient was measured with micromanometers. The calculated effective mitral regurgitant orifice area varied from 10 to 128 mm2, with a consequent regurgitant fraction (regurgitant volume/filling volume) of 24 to 62%. After crushing the sinus node, HR was increased stepwise from 90 to 180 beats/min by atrial pacing while maintaining aortic pressure constant. With increasing HR, filling volume, stroke volume, regurgitant volume and regurgitant time decreased; total cardiac output, forward cardiac output, regurgitant output, systolic pressure gradient, regurgitant fraction and the regurgitant orifice did not change; left ventricular end-diastolic pressure decreased; and left atrial v-wave amplitude increased. These results indicate that in acute experimental MR with a wide spectrum of incompetence, the relative distribution of forward and regurgitant flows did not change with large increases in HR. At rates greater than 150 beats/min the atrial contraction occurs early and increases the amplitude of the left atrial v wave. This may contribute to the severity of pulmonary congestion in patients with MR.

Acute Disease↗