PubMed Health⌕ Search

Biomedical subjects

J R Malm

Publications and source records attributed to J R Malm.

At least 55 records · Page 3Linked to original sources
PubMed1979

Pulmonary atresia with intact ventricular septum. Sixteen-year experience.

Infants with pulmonary atresia and intact ventricular septum (PA-IVS) usually require urgent surgical intervention. Thirty patients with this anomaly, seen at the Columbia-Presbyterian Medical Center between 1962 and 1978, had palliative operations, 26 within the first 3 days of life. Six underwent a closed pulmonary valvotomy alone, with no survivors; six had only a systemic--pulmonary artery shunt, with three early survivors. Because of this experience, 17 had a combined procedure of valvotomy and shunt, with 14 early survivors. One patient recently underwent a definitive right ventricular outflow patch procedure with cardiopulmonary bypass. Eight patients subsequently have had corrective open-heart procedures, with five patients surviving from 2 to 10 years. A unicusp aortic homograft was used for repair in five and a Hancock valved conduit in three. Four patients are presently awaiting operation. We conclude that the initial surgical management of these critically ill infants must not only increase pulmonary blood flow but in addition provide an opportunity for right ventricular growth. Thus we continue to advocate the combined procedure of a valvotomy plus a shunt to provide adequate palliation. Repeat catheterization should be performed within a year to confirm the adequacy of the valvotomy, since this is essential to maximal right ventricular enlargement and to allow for definitive correction at a later date.

Adolescent↗
PubMed1978

Right atrial ultrastructure in congenital heart disease. I. Comparison of ventricular septal defect and endocardial cushion defect.

Ultrastructural studies were performed on portions of the operatively resected right atrium from six patients with a ventricular septal defect and six patients with an endocardial cushion defect. The six patients with a ventricular septal defect had normal right atrial mean pressure and no evidence of right atrial volume overload. Ultrastructurally, the atrial muscle cells in these patients appeared normal and measured 6 to 12 mu in diameter. The six patients with an endocardial cushion defect had elevated right atrial mean pressure and evidence of right atrial volume overload. Ultrastructurally, the atrial muscle cells in these patients were generally larger than 12 mu in diameter. The cells were irregular and had multiple and occasionally widened intercalated discs. In addition, there were degenerative changes in two patients with markedly increased atrial pressure. These changes included extensive loss of contractile elements, aggregation of small irregular mitochondria and proliferation of tubules of the sarcoplasmic reticulum. The structural changes suggest that hypertrophy of the right atrium may be secondary to volume overload of the atrium, whereas degenerative changes may be secondary to increased right atrial pressure.

Basement Membrane↗
PubMed1978

Alpha and beta adrenergic effects on human atrial specialized conducting fibers.

We determined the effects of epinephrine on automaticity and action potential characteristics of right atrial specialized fibers (RAF) from human atria obtained during cardiac surgery. RAF were studied with standard microelectrode techniques during superfusion with Tyrode's solution at 37 degrees C. A biphasic response to epinephrine was seen, rate slowing at low agonist concentrations and increasing at high concentrations. The epinephrine-induced slowing of spontaneous rate was due to a decrease in the slope of phase 4 depolarization. At the high epinephrine concentrations RAF hyperpolarized. The alpha-adrenergic blocker, phentolamine, shifted the dose-response curve upward and to the left and enhanced the hyperpolarization of RAF. The beta blocker, propranolol, shifted the curve to the right and decreased the degree of hyperpolarization. Our study suggests the presence of alpha and beta receptors in RAF. The alpha response consists of a slowing of rate, the beta response of an acceleration of rate and hyperpolarization of RAF.

Action Potentials↗
PubMed1978

Physiological approach to surgery for tricuspid atresia.

A modification of Fontan's approach to the surgical management of tricuspid atresia was employed in nine patients. A valved conduit was used to create continuity between the right atrium and the surgically modified right ventricular chamber. Six patients had had previous shunting procedures. Preoperative studies revealed various degrees of hypoplasia of the right ventricle beneath relatively normal pulmonary valves. At surgery, the atrial septal and ventricular septal defects were closed, the right ventricular chamber was enlarged, and right atrial-right ventricular continuity was established with a valved conduit. There was one operative death. The eight survivors have been clinically well as long as 3 1/2 years following surgery. Postoperative cardiac catheterization was performed in five patients. Ventricularized pressure tracings were recorded in the right ventricular chambers and the morphology of the atrial and pulmonary artery pressure curves were normal. In all instances, angiography demonstrated significant enlargement of a pulsatile right ventricular chamber. Thus, in many patients with tricuspid atresia, establishment of a four-chambered, four-valved heart is feasible, both from an anatomic and physiologic standpoint.

Adolescent↗
PubMed1978

Surgical management of ventricular septal defects in infants.

Infants with ventricular septal defect (VSD) who are symptomatic despite intensive medical therapy require surgical intervention. Choice of treatment depends upon the cumulative mortality and morbidity rates of the two-stage approach of initial pulmonary artery banding followed by debanding and VSD closure as compared to the risk of primary intracardiac repair in infancy. Sixteen infants underwent pulmonary artery banding at Columbia-Presbyterian Medical Center between 1967 and 1976, with one operative death but with a significant incidence of morbidity and late death. Forty patients underwent pulmonary artery debanding and closure of VSD with three operative deaths. This second-stage procedure was frequently complicated by repair of acquired lesions. During the same 10 year period 37 infants underwent primary closure of VSD with eight operative deaths. The morbidity related to this procedure is low. With the use of profound hypothermia and circulatory arrest, results have significantly improved and the risk of early correction now compares favorably with the cumulative mortality rate of the two-stage approach. Primary intracardiac repair is the procedure of choice.

Heart Arrest, Induced↗
PubMed1978

[Counterpulsation by means of a new device with a pulsatile blood flow in open heart operations (author's transl)].

A new counterpulsation method in operations on an open heart is described. Clinical experience in the use of the new device in 124 patients, which also makes it possible to produce a pulsatile flow of blood in the system of extracorporeal circulation, testifies to its effectiveness. The authors claim that the positive changes in cardiac output, diastolic and systolic pressure, and coronary circulation are among the factors which cause an improvement in the final result of the operation in patients with severe valvular diseases and ischemic heart disease.

Adult↗
PubMed1977

A pulsatile assist device (PAD) for use during cardiopulmonary bypass.

A pulsatile assist device (PAD) has been developed to convert roller pump flow to pulsatile flow in a simple fashion. The device can also be used as an arterial counterpulsator before and after cardiopulmonary bypass. The PAD has been used in 125 adult patients undergoing open-heart operations for coronary artery or valvular heart disease or the combination. Ninety-two patients were in New York Heart Association Functional Class III or IV or had ejection fractions of less than 0.3. The PAD functioned as a hemodynamically effective arterial counterpulsator before and after perfusion. All patients were successfully weaned from bypass with the PAD. There has been 1 intraoperative death and 2 late deaths. Only 1 patient had a perioperative myocardial infarction, and this person was successfully treated with intraaortic balloon pumping. We believe the PAD is a simple and reliable device for intraoperative counterpulsation and for the creation of pulsatile cardiopulmonary bypass. More important, use of the PAD may decrease both the incidence of perioperative myocardial infarction and the need for postoperative intraaortic balloon pumping.

Adult↗
PubMed1977

Methods and results of mechanical myocardial support.

In recent years the development of modern direct techniques for revascularization surgery has resulted in a multitude of critically ill patients undergoing open heart surgery. To deal with the increasing numbers of patients who both require urgent open heart surgery and present with many complicated patterns of disease, a spectrum of cardiac assist measures, ranging from simple pharmacological interventions to mechanical cardiac assist techniques, has been developed. Those temporary mechanical cardiac assist devices which employ the principle of couterpulsation and balloon pummping have met with the most consistent clinical success. We now report our experience and progress in this field since early 19729

Adult↗
PubMed1977

An improved method of myocardial protection with pulsation during cardiopulmonary bypass.

A new valveless pulsatile assist device (PAD) has been developed that converts roller pump flow into synchronized pulsatile flow. The PAD can also be used as an arterial counter-pulsator (ACtP) before and after cardiopulmonary bypass (CPB). The PAD was employed in 100 adult patients undergoing open heart surgery for coronary artery and/or valvular heart disease. Seventy-three of these patients were NYHA class III or IV, had ejection fractions of less than 0.3, or an LVEDP greater than or equal to 18 mm Hg. Sixty-one patients underwent coronary artery bypass alone, 17 valve replacement alone, three ventricular aneurysm alone, 12 combined coronaries and valves, and seven combined coronaries and ventricular aneurysms. The device functioned as a hemodynamically effective ACtP before and after CPB. During CPB, pulse pressures of 40-50 mm Hg were readily obtained. Urinary outputs during CPB were increased on the PAD when compared to a control group (9.18 +/- 0.68 cc/min vs 3.90 +/- 0.34 cc/min). In addition, during CPB, coronary graft blood flow (CBF) increased an average of 21.4 +/- 6.1% with the PAD, and after CPB, CBF increased an average of 25.0 +/- 5.9%. Free plasma hemoglobins after CPB were not elevated. Only one patient had a perioperative myocardial infarction, and this patient was successfully treated with intra-aortic balloon pumping. It is suggested from these data that use of the PAD may decrease both the incidence of perioperative myocardial infarction and the need for postoperative intra-aortic balloon pumping.

Assisted Circulation↗
PubMed1977

Acute hemodynamic alterations after aortic valve replacement with the glutaraldehyde-treated porcine heterograft prosthesis.

Twenty-two patients underwent aortic valve replacement for acquired valvular heart disease with the porcine heterograft prosthesis. In the immediate postoperative period, a transient decrease in the cardiac index (CI) (preoperative 3.0 +/- 0.14 to 2.45 +/- 0.16 L. per minute per square meter, p less than 0.05) and an increase in the systemic vascular resistance (SVR) (preoperative 1,078 +/- 62 to 1,287 +/- 103) dynes/sec./cm.-5, p greater 0.05) were seen; these values returned to preoperative levels by the first postoperative day. After valve replacement, an elevation in the heart rate (HR) (preoperative 75 +/- 2 to 87 +/- 4 beats per minute, p less than 0.05) and a reduction in the stroke volume (SV) and stroke work index (SWI) (preoperative 35 +/- 2 to 26 +/- 2 Gm.-M. per square meter, p less than 0.05) occurred which persisted throughout the study. The endocardial viability ration (EVR) increased after valve replacement. These findings suggest that, following aortic valve replacement, (1) an increase HR is the mechanism utilized to maintain cardiac output, (2) subendocardial perfusion is enhanced as indicated by an increase in the EVR, and (3) the hemodynamic alterations following insertion of the porcine heterograft prosthesis are not different from those observed when other valves are placed in similar patient populations.

Adult↗
PubMed1977

Signal enhancement for detection of specialized atrioventricular conduction system electrograms during open-heart surgery.

A method for signal enhancement of electrograms of the specialized atrioventricular conduction system is presented. This method allows a single electrogram to replace the tracings of bipolar electrograms previously required to ensure recognition of the specialezed conduction system and yet maintains the safety afforded by use of three pairs of recording electrodes. In addition, this new signal is enhanced in magnitude and is always unidirectional (positive). These features are desirable for automated signal recognition. This method therefore provides an important step toward future automation and signal recognition of specialized conduction system electrograms during open-heart surgery.

Animals↗
PubMed1977

Increased cardiac output by downstream pumping with a reversed unidirectional intra-aortic balloon.

Downstream and upstream pumping with unidirectional intra-aortic balloons was compared in 8 open-chest normal mongrel dogs anesthetized with pentobarbital. Downstream pumping effect a 32 per cent increase in cardiac index, a 24 per cent decrease in systemic resistance, and a 2 per cent decrease in heart rate. Upstream pumping did not significantly affect these parameters. Mean aorta pressure proximal and distal to the balloon was not altered significantly by pumping in either direction. This unique observation of increased cardiac output may have important implications for the treatment of low output cardiac failure. Preliminary studies including baroreceptor denervation suggest that a reflex mechanism may be involved.

Animals↗
PubMed1976

Open-heart experience in infants using normothermia and deep hypothermia.

During the 9-year period from 1967 through 1975, 124 open-heart operations were performed on infants less than 1 year of age with 35 operative deaths (28%). Ninety-seven of these procedures used continuous cardiopulmonary bypass with normothermia or mild hypothermia, and 27 were done under deep hypothermia and circulatory arrest. Mortality and morbidity were similar regardless of the operative technique, although deep hypothermia facilitated the repair of complex lesions. The highest mortality occurred in infants less than 3 months of age. Respiratory insufficiency, usually requiring prolonged ventilatory support, occurred only among infants who had pulmonary overcirculation or congestion prior to operation. Adequacy of intraoperative repair and postoperative care were the major determinants of survival.

Cardiac Surgical Procedures↗
PubMed1976

Intraoperative recording of the His bundle electrogram in man. An assessment of its precision.

To estimate the effect of distance between the electrode and the signal source on the amplitude of the His bundle electrogram (HBE) recorded during open heart surgery, a specially designed probe, containing six pairs of closely spaced (1 mm) electrodes was placed on the endocardial surface of the right atrium such that each electrode pair was parallel to the course of the His bundle. The amplitude of the HBE recorded through electrodes closest to the His bundle ranged from 0.76 to 2.44 mV, at 1mm from 0.38 to 1.13 mV, at 2mm from 0.27 to 0.86 mV, and at 3 mm from 0.2 to 0.44 mV. Maximal amplitude of HBE decreased by 57% at 1mm, 73% at 2 mm, and 82% at 3mm. The percent decrease was initially rapid, then declined more slowly at distances greater than 1 mm, resembling in form data obtained previously in animal studies by different techniques. Since the maximum HBE was greater than 1.0 mV in nine of 11 patients, and equal to or greater than 1.0 mV in only two of 11 patients at 1 mm, and less than 1.0 mV in all patients 2.0 mm from the maximal HBE, the anatomic location of the His bundle can be estimated from HBE amplitude. Intracardiac electrograms, recorded through closely spaced bipolar electrodes during open heart surgery, afford clinically useful precision in locating the specialized conduction tissue of the heart.

Adolescent↗
PubMed1976

Subpulmonary obstruction in congenitally corrected transposition of the great arteries due to ventricular membranous septal aneurysms.

The clinical, hemodynamic, and angiographic observations, as well as the surgical approach used for repair in three patients with congenitally corrected transposition of the great arteries and ventricular membranous septal aneurysms, are presented. In two of the three patients the membranous septal aneurysm caused subpulmonary obstruction, with 94 and 125 mm Hg systolic gradients. In each patient the aneurysm was demonstrated by angiocardiography, which also showed differences in size and shape with cardiac systole and diastole. Review of the previously described reports indicates that patients with congenitally corrected transposition often display various forms of pulmonary outflow obstruction and when a ventricular membranous septal aneurysm exists, a significant subpulmonary obstruction is present in most patients. The unique anatomic relationship between the pulmonary artery and a ventricular membranous septal aneurysm in patients with transposition of the great arteries with and without atrioventricular discordance explains why subpulmonary obstruction sometimes develops.

Adolescent↗