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Biomedical subjects

Y Hasin

Publications and source records attributed to Y Hasin.

15 recordsLinked to original sources
PubMed1992

Autodecremental pacing for the interruption of ventricular tachycardia and atrial flutter.

The efficacy and safety of autodecremental pacing (ADP) to interrupt ventricular tachycardia (VT) and atrial flutter was examined. Once tachycardia was recognized, ADP was initiated using a short train of stimuli with gradual shortening (3%) of the interstimulus interval. ADP was applied to 13 consecutive patients during 75 episodes of VT (mostly following induction by ventricular stimulation). Successful interruption of VT occurred in 88% of the episodes. In 6 episodes (8%), ADP resulted in ventricular fibrillation and in 3 episodes VT was unaffected by ADP. The only significant discriminator between the failure or success of ADP was the rate of VT. ADP was also applied to 17 consecutive patients with an atrial flutter that was resistant to conventional antiarrhythmic agents. Successful conversion of atrial flutter to sinus was seen in only 8 patients (47%). A temporary acceleration to atrial fibrillation appeared in 3 patients (18%), and in 6 patients atrial flutter was unaffected by ADP. ADP was successful in 70% (7/10) of patients with type 1 (< 300 beats/min) atrial flutter. The authors conclude that ADP is beneficial in the interruption of VT and atrial flutter in a selected group of patients, especially with a slower rate of tachyarrhythmia (atrial rate during atrial flutter < 300 beats/min and ventricular tachycardia < 180 beats/min).

Adult↗
PubMed1979

Relationship between extent of coronary artery disease and correlative risk factors.

An analysis was made of correlative factors which might be related to the angiographically measured extent of coronary artery disease in 140 patients. All patients presented with clinically important chest pain. Thirty-three had a normal coronary arteriogram. The extent of the atheromatous process was measured precisely at angiography by three different techniques. A coronary score, based on the percentage of luminal narrowing, was found to be best suited for the analysis. The most important contributory factors to the severity of atherosclerosis was duration of clinical history, number of previous myocardial infarctions, and male sex, but more specifically elevation of serum cholesterol and diabetes mellitus. Cigarette smoking, obesity, hypertension, a family history of atherosclerosis, and elevated serum triglycerides had a positive influence but this was not statistically significant.

Angina Pectoris↗
PubMed1979

Co-existing aortic stenosis and secondary hypertrophic cardiomyopathy manifested by an hourglass left ventricle. Successful treatment with verapamil.

A patient with moderate aortic stenosis had severe hypertrophy and a typical hourglass appearance of the left ventricle. His effort-induced angina and dyspnea responded to treatment with verapamil. We suggest that the aortic stenosis resulted in secondary hypertrophic cardiomyopathy which may be treated by calcium antagonists.

Aortic Valve Stenosis↗
PubMed1979

Electrical and mechanical response in biventricular mechanical alternans.

Mechanical alternans of various degrees is produced by rapid heart rates, slower rates in failing hearts and can be brought about by a single extra systole. It has also been shown that the two ventricles may exhibit different degrees of mechanical alternation. The present study was planned to clarify the possible mechanism inducing this latter phenomenon. For this reason myocardial tension was recorded simultaneously from the two ventricles as well as through a miniature strain gage capable of measuring electrogram and myocardial tension of a small area -- just adjacent to a stimulating electrode. The heart was driven at a steady heart rate through one electrode and very late premature beats were applied at various coupling times at another site through an electrode attached to the miniature strain gage. It was found that the degree of mechanical alternans is markedly different at the sites of measurements in either ventricle. These changes could be related to the time interval elapsed between the application of the electrical stimulus and the occurrence of the mechanical response.

Animals↗
PubMed1979

Echocardiographic aortic root motion in ventricular volume overload and the effect of mitral incompetence.

Echocardiographic aortic root motion in systole was studied in 57 patients: 13 normal subjects, 4 patients with left ventricular (LV) volume overload due to anaemia, 16 patients with mitral incompetence, 13 with aortic incompetence and 11 with mitral stenosis. In normal subjects, patients with mitral stenosis and in patients with LV volume overload, in whom the increased stroke volume was ejected forwards into the ascending aorta (anaemia, aortic incompetence) the amplitude of motion of the posterior aortic wall (vp), the aortic widening fraction (AWF) and total aortic motion (TAM) were increased. In mitral incompetence, however, despite the large increase in total LV stroke index, there was a decrease in vp (P less than 0.01), AWF (P less than 0.001) and TAM (P less than 0.001), and the decrease in aortic motion for a given stroke index was related to the mitral regurgitant fraction, indicating that aortic wall movement in systole depended predominantly on forward ejection of the LV stroke volume. Reduced echocardiographic aortic root motion and widening during systole are useful echocardiographic signs of mitral regurgitation.

Anemia↗
PubMed1978

A new hazard in the use of an external demand pacemaker.

Ventricular pacing by a Medtronic model 5880A external demand pacemaker was shown to be inhibited as long as the metal coverplate of the pacemaker was touched with bare hands. The asystolic periods were induced by a previously undescribed malfunction of the pacemaker, inherent in its structure. This phenomenon occurred when both patient and physician were isolated from any main operated instrument. It could be demonstrated that pacer inhibition was induced by capacitive coupled 50 Hz fields from the environment, activating the sensing mechanism through the metal coverplate. The plastic covered Medtronic model 5840 pacemaker does not have such undesirable characteristics.

Electrocardiography↗
PubMed1978

Transtelephone adjustment of antiarrhythmic therapy in ambulatory patients.

The electrocardiograms of 80 ambulatory patients receiving antiarrhythmic therapy were supervised with the help of a transtelephone monitoring system. The patients used a pocket-size modulator and reported several times daily to the receiving center integrated into the intensive cardiac care unit. The surveillance lasted for 5-28 days during which various drugs in varying dosages were administered to suppress or prevent dysrhythmias. In 94% of the patients, a satisfactory therapeutic achievement was obtained. The transtelephone system provides easy diagnosis, immediate pattern recognition, direct and frequent contact with the ambulatory patient and long periods of follow-up. During this time, the proper antiarrhythmic agent can successfully be defined, its effective dose can safely be determined and unnecessary hospitalization can thus be prevented.

Adult↗
PubMed1978

Ventricular ectopic rhythms due to rapid runaway pacemaker.

A patient initially had syncope due to a runaway pacemaker firing at an unusually rapid rate (30 impulses per second). The ventricular arrhythmia was characterized by numerous ectopic beats, with coupling intervals related to the length of the preceding cycle and runs of ventricular tachycardia with slight variations in the intervals between beats. This case demonstrates the clinical characteristics of a very rapidly firing, low-intensity, ventricular parasystolic focus.

Arrhythmias, Cardiac↗
PubMed1978

Propranolol-induced dysfunction of the sinus node in Wolff-Parkinson-White syndrome.

We report the findings in a patients with the Wolff-Parkinson-White syndrome (type A) who initially had recurrent fainting episodes. It appeared that they were caused by prolonged posttachycardiac depression of the sinus node, which was induced by treatment with propranolol. The possibility of covert dysfunction of the sinus node in patients with Wolff-Parkinson-White syndrome should be considered before commencing therapy with beta-adrenergic blocking agents.

Adult↗
PubMed1977

In vivo atrial excitability and anti-arrhythmic drugs.

The threshold of excitability of the atrial muscle was studied in the in vivo beating canine heart. Unipolar cathodal and anodal strength-interval curves were constructed and found to be dissimilar in shape. It was found that at any interval within the relative refractory period of the atrium, as in the ventricle, there is a wide range of current levels delineated by an upper (TU) and lower (TL) limit of threshold which can stimulate the atrial myocardium. Within these limits the threshold varies spontaneously and can be reduced to TL level by a run of extrasystoles. Such TU and TL curves were repeatedly determined following administration of therapeutic doses of quinidine, procaine amide or lidocaine. It was observed that all three drugs prolonged the refractory period. The TU values increased following each of the drugs, and mostly after quinidine, while the TL curve was less affected by quinidine. It is suggested that the exit block thus produced is the principal mechanism whereby quinidine depresses atrial disrhythmias.

Animals↗
PubMed1976

Diagnostic and therapeutic assessment by telephone electrocardiographic monitoring of ambulatory patients.

The electrocardiograms of ambulatory patients have been monitored over the telephone by staff of the intensive cardiac care unit using equipment in the unit. Telephone monitoring is a useful way of diagnosing transient symptomatic arrhythmias and a reliable aid in supervising the patient's rhythm at the beginning or end of treatment. The doctor has direct contact with the patient at the time of his symptoms so that he can reassure or instruct him. This system costs relatively little in manpower and equipment and permits relatively long periods of follow-up. It is effective, however, only in symptomatic cases in which the rate or rhythm disturbances last long enough to be transmitted. Also important are the negative findings when the patient complains of symptoms and abnormal findings during routine telephone transmissions. Accurate detection of transient ischaemic changes seems to be less reliable, and further technical improvements are required.

Adult↗
PubMed1976

Ventricular rhythms in acute myocardial infarction.

Ectopic ventricular activity in acute myocardial infarction is considered to be benign if it is slow and regular (accelerated idioventricular rhythm), but ominous when rapid (ventricular tachycardia). However, it has been observed in an increasing number of reports that these two types may coexist in the same patient, altering thereby the clinical significance of both. In the present study electrocardiograms were analyzed of 55 patients hospitalized for acute myocardial infarction, in whom idioventricular rhythm occurred. It was found that three major types of ventricular rhythms could be identified: a regular-stable rhythm, an irregularunstable one, and a third variant which was a combination of these two types. The stable ventricular rhythm was self limited and harmless. The unstable and combined types which were characterized by random coupling times and varying interbeat intervals, were frequently associated with re-entrant beats and fast ventricular rates and therefore a potentially ominous prognosis. It is suggested that the Ca++ dependent slow diastolic depolarization may be the mechanism responsible for the unstable ventricular rhythm, and the reasons for this assumption are discussed. A therapeutic approach based on the above considerations is described.

Acute Disease↗
PubMedDate not supplied

Right and left ventricular flow during mechanical alternans.

Pulmonary and aortic blood flow simultaneous with right and left ventricular isometric tension were measured in anesthetized dogs during mechanical alternans induced by rapid atrial driving. It was found that any steady state of mechanical alternation can be altered to another steady state by a single premature or delayed beat. The relationship between the force of the alternating beats was not necessarily equal in the two ventricles. Pulmonary and aortic flow changed markedly with changing steady states of mechanical alternation, at the same heart rate, within wide range of flow levels. Moreover, inequality between the mechanical alternation of the two ventricles was at times associated with disparity of aortic and pulmonic flow. The possible mechanism and clinical significance have been mentioned.

Animals↗