Search PubMed⌕ Search

Biomedical subjects

M Rubenfire

Publications and source records attributed to M Rubenfire.

At least 109 records · Page 6Linked to original sources
PubMed1978

Noninvasive recording of His-Purkinje activity in man by ORS-triggered signal averaging.

Mobile instrumentation and a clinically applicable method have been developed for external His bundle recording. High gain signal amplification (10)(5) filtering (30--300 HZ) and averaging (128 or 256 consecutive cycles) are used. Acquisition of signals arising in the P-R interval is triggered by the patient's QRS signal at the end of that interval. The precordial bipolar electrodiogram is digitized at 5k HZ with 8 bit resolution and transferred to a 1,024 word, 18 bit signal averager. The averaged signal is then displayed on an oscilloscope and photographed. Good correlations were obtained between direct intracardiac and precordial recordings in experimental animals and in humans. Noise level after averaging was below 0.3 microV, and there was good elimination of asynchronous atrial and ectopic ventricular activity. With averaging of 128 or 256 consecutive cycles, the signal attenuation after propagation to the chest wall was in the range 1:2000 to 1:4000 in comparison with the directly recorded His bundle activity deflections. The noninvasive method may be of value in follow-up of acute and chronic disturbances of atrioventricular conduction, as well as in studies of effects of pharmacologic interventions.

Animals↗
PubMed1978

The clinical significance of bundle branch block complicating acute myocardial infarction. 1. Clinical characteristics, hospital mortality, and one-year follow-up.

To provide an understanding of the clinical characteristics of patients with acute myocardial infarction (MI) and bundle branch block, experience from five centers was accumulated. Patients in whom bundle branch block first appeared after the onset of cardiogenic shock were excluded. In 432 patients, the most common types of block were left (38%) and right with left anterior fascicular block (34%). In 42% of the patients, bundle branch block was new. Progression to high degree (second or third degree) atrioventricular (AV) block via a Type II pattern occurred in 22% of the patients. Hospital and first year follow-up mortality rates were 28% and 28%, respectively. Only 46% of the patients developed pulmonary edema or shock (Killip Class III or IV), and hospital mortality was related to the amount of heart failure (8%, 7%, 27%, 83% for Killip Classes I-IV, respectively). Patients with progression to second degree or third degree AV block via a Type II pattern had increased hospital mortality compared with patients without this complication (47% vs 23%, P less than 0.001). In the absence of pulmonary edema or shock, patients with Type II second degree or third degree AV block still had a higher mortality rate than patients without advanced AV block (31% vs 2%, P less than 0.005), with nearly all the deaths due to abrupt development of AV block. Thus, in many patients MI with bundle branch block is associated with severe heart failure. However, this was not true for a majority of the patients, in whom therapy aimed at preventing morbidity and mortality due to the bradyarrhythmia of advanced AV block might be beneficial.

Acute Disease↗
PubMed1978

The clinical significance of bundle branch block complicating acute myocardial infarction. 2. Indications for temporary and permanent pacemaker insertion.

The indication for prophylactic temporary and permanent pacing during acute myocardial infarction (MI) complicated by bundle branch block is high risk of progression via a Type II pattern to second or third degree (high degree) AV block during hospitalization or follow-up. In this study, determinants of high degree AV block during hospitalization and sudden death or recurrent high degree block during the first year of follow-up were examined in 432 patients with MI and bundle branch block. Timing of onset of bundle branch block, the involved fascicles, and the PR interval were examined as determinants of risk of progression to high degree AV block during MI. At highest risk were 186 patients with blocks involving the right bundle and at least one fascicle of the left bundle which were not documented on prior electrocardiograms. Risk was similar with (38%) or without (31%) accompanying first degree AV block. Patients with transient high degree AV block during MI had a 28% incidence of sudden death or recurrent high degree block during the first year of follow-up. Patients not continuously paced had a higher incidence of sudden death or recurrent high degree block than patients continuously paced (65% vs 10%, P less than 0.001). Sudden death during follow-up also occurred in 13% of patients without high degree block during MI. A subgroup with 1) documented prior MI, 2) anterior or indeterminant acute MI, and 3) no symptoms of cardiac failure had a 35% risk of sudden death. The role of permanent pacing in this group is unknown. Thus, patients at high risk of high degree AV block should receive prophylactic temporary pacing. Patients who survive high degree block with MI should receive temporary and then permanent pacing. Patients without high degree AV block during MI who nervertheless have a high risk of sudden death may benefit from permanent pacing.

Adult↗
PubMed1976

Neuropathy in the upper extremity after open-heart surgery.

Eleven patients with upper-extremity neurological abnormalities underwent open-heart surgery performed through a median sternotomy incision. Seven of the 11 patients were referred in the routine manner to evaluate and treat the neurological problem. The remaining four were part of a consecutively studied group of 11 patients examined prospectively to determine the possible presence of abnormalities. Two of these four patients were asymptomatic. All lesions could be postulated to occur within the brachial plexus, the most common area being the median cord, but lesions were also noted in the posterior and lateral cords and upper trunk. The etiology of the problem appears to be stretching injury of the brachial plexus from retraction of the sternum, which in turn causes retroclavicular displacement of the clavicle. However, it is possible that an ischemic neuropathy could result from intraarterial procedures in some of our patients. The possibility that neurologic deficit may occur in the upper extremity should be considered by physicians who may have the opportunity to evaluate patients who undergo open-heart surgery.

Adult↗
PubMed1975

Patient selection for cardiac surgery in left ventricular power failure.

Nineteen patients in acute left ventricular power failure following acute myocardial infarction were given support with intraaortic balloon pumping and underwent cardiac catheterization. Hemodynamic response to disastolic augmentation, results of left ventriculography, and observations of selective coronary arteriography were evaluated to determine which patients could survive without operation, which would require operation to survive, and which could be predicted not to survive operation. Of ten patients who underwent operation, three were long-term survivors. Two patients predicted to have a good prognosis without surgery did survive. Of three patients who had been determined to require operation but not undergo it, two died in the hospital and one a month later. The four patients whose conditions were considered inoperable died in the hospital. The results indicate that current methods of predicting the need for corrective surgery are relatively accurate and that the rate of survival in surgically treated patients may be increased.

Assisted Circulation↗
PubMed1975

Demonstration of lack of persistence of effectiveness of intra-aortic balloon pumping of short duration in acute myocardial ischemia.

Experimental studies were carried out to quantitate the effectiveness of intra-aortic balloon pumping (ABP) in reducing severity and extent of myocardial ischemia and the persistence of induced changes after cessation of pumping. Ligation of the anterior descending coronary artery was followed by one hr of observation, IABP for one hr (12 dogs) or 3 hrs (12 dogs) and an additional one hr of observation. Epicardial mapping utilizing 20 electrodes was used to obtain the ST segment elevations (Sigma ST) and numbers of electrodes showing ischemic ST CHANGES (NST) in each group. Reductions of SigmaST of approximately 15% and 33% and reduction of NST of 15% and 20% was observed in the one and 3 hr groups respectively, and persisted throughout the period of pumping. Both parameters were noted to increase within 5 mins after cessation of IABP in both groups. SigmaST frequently rose to almost pre-IABP values in the group pumped for one hr. The group pumped for 3 hrs showed SigmaST increase of approximately 15% and NST increase of approximately 16%. Hemodynamic measurements showed in both groups a mean systolic unloading of approximately 10% and 10-20% mean diastolic augmentation. In conclusion, IABP of short duration (1-3 hrs) early after the onset of acute ischemis (one hr) induces a significant but transient decrease in SigmaST and NST, which reflects a reduction in myocardial ischemia. Further study is required to evaluate the effectiveness of intra-aortic balloon pumping, if intitated several hours after the onset of ischemia, to reproduce the clinical reality of a patient with an acute myocardial infarction.

Animals↗
PubMed1975

Neurological abnormalities in the leg(s) after use of intraaortic balloon pump: report of six cases.

Six patients from a group of 39 who survived after treatment with the intraaortic balloon pump (lABP) had significant neurological deficits in one or both legs associated with the use of the lABP. The device was used in a group of 89 patients initially for cardiogenic shock but its use has been expanded for patients having the following conditions: preshock; severe congestive heart failure; refractory angina; and for those undergoing open-heart surgery. The six patients who had neurological sequelae had eight lABP insertions into the thoracic aorta through the femoral artery and had neurological abnormalities and/or electromyographic abnormalities in nine lower extremities ranging from a foot drop to almost total paralysis of the lower extremity. The pathophysiology of the neurological deficit is postulated to be an obstruction to blood flow, or thromboemboli, in the femoral artery.

Adult↗