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Biomedical subjects

J D Murphy

Publications and source records attributed to J D Murphy.

At least 55 records · Page 3Linked to original sources
PubMed1988

The significance of tricuspid regurgitation in hypoplastic left-heart syndrome.

Palliation of hypoplastic left-heart syndrome involves use of the morphologic right ventricle as the systemic ventricle and the tricuspid valve (in cases of mitral atresia/stenosis) or the common atrioventricular valve (in cases of malaligned atrioventricular canal) as the systemic atrioventricular valve. To determine the relationship between tricuspid or common atrioventricular valve function and the ultimate outcome of palliative surgery, 100 patients with hypoplastic left-heart syndrome were evaluated preoperatively by Doppler echocardiography to determine the degree of tricuspid regurgitation. These patients were then followed serially to assess changes with time in the functional status of the tricuspid or common atrioventricular valve and to determine the correlation of tricuspid or common atrioventricular valve regurgitation with survival. We discovered that tricuspid or common atrioventricular valve regurgitation is common in hypoplastic left-heart syndrome. Thirty-seven percent of the patients had mild, 13% had moderate, and 3% had severe tricuspid or common atrioventricular valve regurgitation on their preoperative Doppler echocardiograms. Throughout the first 2 postoperative years most patients had no significant change in the degree of tricuspid or common atrioventricular valve regurgitation when findings were compared to those of the preoperative echocardiogram. Patients with moderate or severe tricuspid or common atrioventricular valve regurgitation preoperatively had a significant reduction in their survival when contrasted with patients with no or mild atrioventricular valve regurgitation. We therefore conclude that tricuspid or common atrioventricular valve competence is a significant factor in long-term survival after palliative surgery for hypoplastic left-heart syndrome. This function, however, appears to be unaffected by palliation and remains relatively constant over the first 2 postoperative years.

Female↗
PubMed1988

Palliative reconstructive surgery for hypoplastic left heart syndrome.

From August, 1985, through August, 1987, 104 consecutive, nonselected neonates underwent palliation of hypoplastic left heart syndrome. The technique included pulmonary artery homograft augmentation of the diminutive ascending aorta and aortic arch, atrial septectomy, transection of the main pulmonary artery with patch closure of the distal main pulmonary artery, anastomosis of the proximal main pulmonary artery to the augmented ascending aorta, and a 4-mm, modified, right Blalock-Taussig (N = 21) or central (N = 83) shunt. There were 30 early and 11 late deaths. Early mortality was most commonly associated with hypoventilation. Complications included development of aortic arch obstruction (N = 11) and progressive hypoxemia (N = 11). Alterations in surgical techniques and perioperative management should permit continued improvement in early and long-term survival.

Aorta↗
PubMed1987

Intraoperative balloon angioplasty of aortic coarctation in infants with hypoplastic left heart syndrome.

During a 1-year period, 9 children, aged 3 to 18 months, underwent intraoperative transluminal balloon angioplasty of coarctation of the aorta. Each patient had previously undergone palliative surgery for hypoplastic left heart syndrome. In 1 patient the angioplasty catheter was introduced into the ascending aorta during surgery to correct intracardiac defects. In the other 8 infants the catheters were inserted directly into the descending thoracic aorta via thoracotomy because the catheter size precluded percutaneous insertion into the femoral artery. In each case, after measuring the systolic pressure gradient across the coarctation, the angioplasty catheters were advanced over the guidewire across the coarctation site. The balloons were then inflated 2 to 3 times with an internal pressure of 3 to 6 atm. After the dilation sequence the angioplasty catheters were removed and the pressures were again measured above and below the coarctation. Preoperative gradients across the coarctation site ranged from 26 to 85 mm Hg (mean 45). Immediately after the procedure the gradient decreased in each case, ranging from 0 to 12 mm Hg (mean 4.3). There were no signs of disruption of the aortic wall. Relief of the pressure gradient persisted in the 7 patients who underwent follow-up cardiac catheterization after the procedure. The patients have been followed for as long as 18 months after the procedure and none has shown physical or echocardiographic evidence of recurrent aortic obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1987

Effects of indomethacin in utero on the pulmonary vasculature of the newborn guinea pig.

The clinical syndrome of persistent pulmonary hypertension of the newborn results from failure of the normal perinatal vascular adaptation, and functionally is characterized by persistent right to left shunting of blood through the foramen ovale and ductus arteriosus. Exposure of the fetus to drugs that inhibit prostaglandin synthesis and cause closure of the ductus arteriosus has been suggested as one cause of persistent pulmonary hypertension of the newborn. We attempted to produce a functional and structural model of persistent pulmonary hypertension of the newborn by administration of indomethacin, a cyclooxygenase inhibitor, to pregnant guinea pigs. Five pregnant guinea pigs received 3.5 mg/kg indomethacin intravenously twice each day for the 12 to 19 days before delivery and seven controls received saline. Hemodynamic studies were performed in eight "treated" newborns and in 12 controls. After sacrifice, the ductus was ligated and, for morphometric studies, the pulmonary arteries were distended with barium/gelatin. The treated animals did not show the intraacinar structural or hemodynamic changes of persistent pulmonary hypertension of the newborn. It seems that the indomethacin did cross the placenta because lung structure was modified. The radical alveolar count and alveolar/artery ratio were increased and the preacinar arteries dilated, with more increase in muscle mass. This could be explained by increased pulmonary blood flow because of ductal constriction but direct effect of indomethacin cannot be excluded.

Animals↗
PubMed1986

Postmortem echocardiography and tomographic anatomy of hypoplastic left heart syndrome after palliative surgery.

A study was undertaken to improve the understanding of the 3-dimensional (3-D) topology of a complex surgical reconstruction. The pathologic anatomy was investigated by first fixing postmortem heart specimens in such a way as to preserve the 3-D relations. Next, a technique for postmortem 2-D echocardiography was developed to aid in selection of tomographic planes for sectioning the specimens. Subsequent adjustment of planes of section was made to better show particular facets of the anatomy. The material for this investigation was drawn from cases of hypoplastic left heart syndrome after surgical palliation by the Norwood procedure. Three potential hemodynamic sequelae--restrictive inter atrial communication, aortic obstruction at any level and distortion of the pulmonary artery confluence--served as the anatomic focus for this study. Careful preservation of 3-D topology and postmortem 2-D echocardiographic imaging coupled with tomographic sectioning of specimens led to development of new, clinically relevant echocardiographic views for imaging specific atrial septal and aortic arch anomalies. These techniques offer insight into the spectrum of anatomic sequelae of this type of surgery and may be applied to echocardiographic imaging of patients and refinement of surgical technique for other forms of complex congenital heart disease.

Aorta, Thoracic↗
PubMed1986

Effects of chronic in utero hypoxia on the pulmonary vasculature of the newborn guinea pig.

This report analyzes the effect on pulmonary vascular structure and function in the newborn guinea pig of chronic fetal hypoxemia, induced by maternal hypobaric hypoxia (380-420 torr) without direct interference with the utero-placental blood flow. Six pregnant guinea pigs were maintained in hypobaric chambers, 10 newborns from their litters being the hypoxic group. Twenty newborns from the litters of 10 pregnant guinea pigs maintained in air were the control group. After spontaneous delivery catheters were placed in the left carotid and the main pulmonary arteries of the newborns. Oxygen consumption was measured, pressures recorded from the pulmonary artery, right ventricle, and right atrium, oxygen saturation and hemoglobin concentration estimated on blood from systemic arteries, pulmonary artery, and right atrium, and cardiac output calculated (Fick principle). All data were normalized per kilogram body weight. Morphometric analysis of the pulmonary vasculature after injection of the pulmonary arteries showed no difference between the groups. Contrary to expectation chronic hypoxemia in utero did not cause pulmonary hypertension or the precocious muscularization of the precapillary unit found in human cases of persistent pulmonary hypertension: it caused growth retardation, a feature not typical of the human syndrome.

Animals↗
PubMed1986

Analysis of potential anatomic or physiologic determinants of outcome of palliative surgery for hypoplastic left heart syndrome.

Sixty-five consecutive patients with hypoplastic left heart syndrome underwent preoperative two-dimensional echocardiographic examination (and Doppler examinations in 33) to assess parameters potentially predictive of early (less than or equal to 30 days) mortality after palliative surgery. The six anatomic and physiologic factors considered were right ventricular wall thickness, right ventricular shortening, tricuspid (or common atrioventricular valve) regurgitation, ascending aortic size, distal aortic arch anatomy, and atrial septal anatomy. Right ventricular wall thickness was 3 or 4 mm in 59 of 65 patients and did not correlate with outcome. There was no significant difference in early mortality between patients with abnormal right ventricular shortening (11 of 23 patients [48%]) and those with normal right ventricular shortening (19 of 42 patients [45%]). Tricuspid or common atrioventricular valve regurgitation was found in 15 of 33 patients and eight of these suffered early death (53%) compared with six (33%) among the 18 patients without atrioventricular valve regurgitation. Ascending aortic diameter ranged from 2 to 6 mm and did not correlate with early outcome. Coarctation of the aorta, found in 18 of 54 patients (33%), and leftward displacement of the superior attachment of septum primum, noted in 33 of 63 patients (52%), likewise did not correlate with outcome. Therefore, at present, variations in the six parameters analyzed cannot be considered contraindications to palliative surgery in patients with hypoplastic left heart syndrome.

Echocardiography↗
PubMed1985

Congenital diaphragmatic hernia: arterial structural changes and persistent pulmonary hypertension after surgical repair.

Some infants with congenital diaphragmatic hernia who die after surgical correction have a transient postoperative period during which systemic oxygenation is adequate (honeymoon period), whereas others have persistent hypoxemia. Using morphometric techniques, we analyzed lung structure, especially the arterial bed, in seven infants who died within 1 week of surgical repair. Three infants comprised the honeymoon group, the PaO2 transiently being greater than 150 mm Hg in the descending aorta (FiO2 1.0); four infants comprised the no-honeymoon group and never had PaO2 greater than 85 mm Hg. All lungs were hypoplastic for age; with one exception, infants in the no-honeymoon group had smaller lungs. Arterial structure in the no-honeymoon group contributed to a greater reduction in pulmonary arterial cross-sectional area. Each infant in the no-honeymoon group had muscularization of intra-acinar arteries and failure of perinatal increase in compliance of small preacinar arteries, features not seen in the honeymoon group or in the normal newborn infant. In addition, compared with the honeymoon group, luminal area of preacinar and intra-acinar arteries in the no-honeymoon group was decreased by reduced external diameter or increased medial thickness. Clinical deterioration in the honeymoon group is based on a vasoconstrictive response of the hypoplastic vascular bed. Persistent hypoxemia in the no-honeymoon group is based on both severity of pulmonary hypoplasia and structural remodeling of the pulmonary arteries.

Arteries↗
PubMed1984

The pulmonary hemodynamic response to perioperative anesthesia in the treatment of high-risk infants with congenital diaphragmatic hernia.

The continuing high mortality in congenital diaphragmatic hernia led us to study the cardiopulmonary disturbances associated with this lesion. Since these infants infrequently have right-to-left shunting in the operating room, we adopted a treatment protocol of: continuing general anesthesia in the postoperative period using fentanyl and pancuronium; cardiac catheterization postoperatively, including placement of a pulmonary artery line and a pulmonary angiogram; rapid frequency ventilation; moderate fluid restriction; and avoidance of vasodilators until other means of management had clearly failed. Fourteen high-risk infants, presenting within 6 hours of birth, were studied and compared to 17 high-risk infants, who served as historical controls. As revealed by the physiologic data acquired in the catheterization laboratory, high-risk infants divided into "Responder" and "Nonresponder" groups. Seven of 10 "Responders" actually shunted left to right during the catheterization, demonstrating a low pulmonary vascular resistance. Seven of 10 subsequently demonstrated significant right-to-left shunting at the level of the ductus and the foramen ovale, indicating the hyperreactivity of the pulmonary vascular bed. All but one was managed successfully by ventilatory adjustments and deepening of the level of anesthesia. "Nonresponders" had a fixed right-to-left shunt unresponsive to any medical or ventilatory manipulation. All "Nonresponders" died. Pulmonary angiography suggested a smaller diameter of the affected pulmonary artery compared to the main pulmonary artery in the "Nonresponders." This implies true hypoplasia resulting in a vasculature too small to accept a full cardiac output. Survival in the treatment group "Responders" was eight of 10 (80%) v seven of 14 (50%) in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗
PubMed1984

Pulmonary vascular disease in fatal meconium aspiration.

Although not proved, it is generally accepted that pulmonary vasospasm is responsible for the persistent pulmonary hypertension frequently associated with meconium aspiration. We have studied the pulmonary vasculature in 11 consecutive infants with fatal meconium aspiration, applying morphometric techniques to pulmonary arteries distended with barium gelatin before fixation. In 10 of the 11 infants, persistent pulmonary hypertension was evident clinically, with right-to-left shunting through the foramen ovale or ductus arteriosus. In all but one, severe structural abnormal muscularization of the smallest intra-acinar arteries was present. These changes must have developed before birth. In only one infant was the structure of the intra-acinar precapillary arteries virtually normal, as would be expected if vasospasm alone had caused the hypertension. The persistent pulmonary hypertension associated with fatal meconium aspiration may be the result of a structurally abnormal pulmonary microcirculation.

Female↗
PubMed1983

Management of infants with left ventricular outflow obstruction by conduit interposition between the ventricular apex and thoracic aorta.

On the basis of experience with older children, creation of a double-outlet ventricle by interposition of a valved conduit between the apex of the left ventricle and the thoracic aorta appeared to be an option for treating life-threatening left ventricular outflow tract obstruction even in the small heart of the infant. Over the recent 3 year period, nine infants ranging in age from 3 days to 13 months with various forms of left ventricular outflow tract obstruction underwent placement of an apical-aortic conduit to decompress the hypertensive left ventricle. There were two early and two late deaths. Five patients are clinically well and developing normally 5 to 23 months following the operation. This series demonstrates that this operation permits normal growth and development in infants previously failing to thrive. Echocardiographic and cardiac catheterization data suggest that left ventricular function need not be adversely affected by placement of a stent in the small infant ventricle; rather, ventricular function can be markedly improved. Although the mortality in this series is appreciable, it appears that apical-aortic conduit interposition can provide significant palliation for infants with otherwise lethal left ventricular outflow tract obstruction.

Aorta, Thoracic↗
PubMed1981

The structural basis of persistent pulmonary hypertension of the newborn infant.

Six neonates of 35 to 42 weeks' gestation had findings of persistent pulmonary hypertension and died between one and 6 days of age despite intensive medical therapy. Each patient had pulmonary artery pressure near or above systemic level, with a right-to-left shunt via the foramen ovale and/or ductus arteriosus. At postmortem, morphometric analysis of the peripheral pulmonary vascular bed revealed extension of muscle into small arteries, which was severe in five of six patients; all alveolar duct and wall arteries (less than 30 micrometers external diameter), normally nonmuscular, were fully muscularized. In these five patients medial wall thickness of the normally muscular intra-acinar arteries was doubled; arterial size and number, however, were normal in all. This striking structural maldevelopment of the peripheral pulmonary arterial bed occurred or was initiated in utero and does not merely represent a failure of the fetal pattern to regress. We suggest that this particular group of patients remained refractory to all current modes of therapy because of these severe structural pulmonary vascular changes.

Humans↗
PubMed1978

The risk of advanced heart block in surgical patients with right bundle branch block and left axis deviation.

The risk of advanced atrioventricular block during anesthesia was studied prosepctively in 44 patients with right bundle branch block and left axis deviation who underwent a total of 52 operations over a 14 month period. All patients had continuous electrocardiographic monitoring throughout anesthesia induction, operation, and surgical recovery. Of the 52 operative procedures, 24 were done under general anesthesia, 11 under spinal, and 17 under local. The preoperative cardiac rhythms were atrial fibrillation in two patients, atrial tachycardia with block in one patient, atrial flutter in one patient, and sinus rhythm in the remaining patients. Temporary pacemakers were inserted preoperatively in six patients, usually because of PR interval prolongation on the preoperative electrocardiogram. There was only one episode of transient complete heart block in 51 of the 52 operative procedures. In two of the six patients with temporary pacemakers, significant pacer-related ventricular irritability occurred. This study indicates that temporary pacemaker insertion is rarely required in patients with chronic right bundle branch block and left axis deviation who require noncardiac surgery.

Adult↗
PubMed1976

Myocardial ischemia due to infrarenal aortic cross-clamping during aortic surgery in patients with severe coronary artery disease.

Hemodynamic measurements were performed and ECG recorded before and shortly after infrarenal aortic cross-clamping during operation for abdominal aortic aneurysm in five patients without evidence of heart disease (group I) and in ten patients with severe coronary artery disease (group II). All patients sustained an increase in systemic arterial pressure. Group I demonstrated a decrease in pulmonary artery, pulmonary capillary wedge (PCW), and central venous pressures when the aorta was clamped, whereas group II demonstrated an increase. The difference in response of the groups is significant (P less than 0.05). All three patients who responded to cross-clamping with increases of 7 mm Hg or greater in PCW demonstrated myocardial ischemia during cross-clamping. None of the values measured prior to cross-clamping predicted with certainty the response to cross-clamping. Sodium nitroprusside reversed the elevation of left ventricular filling pressure in all three patients, and in two patients, relieved evidence of myocardial ischemia concurrently. In the third patient, ventricular irritability was abolished by lidocaine and did not recur. We conclude that infrarenal aortic cross-clamping may cause myocardial ischemia in patients with severe coronary artery disease. This ischemia may be predicted by a rise in PCW at the time of cross-clamping, and vasodilator therapy is indicated in such patients.

Aged↗
PubMed1975

Transtracheal ventilation.

Effective percutaneous oxygenation and ventilation can be achieved through the use of transtracheal catheters. A graphic study of pressure-flow requirements through different-sized catheters can serve as a guide for the caliber and driving pressure requirement to obtain optimal oxygen flow.

Acute Disease↗
PubMed1975

Train-of-four nerve stimulation in the management of prolonged neuromuscular blockade following succinylcholine.

Four patients, all possessing an atypical form of plasma cholinesterase, developed prolonged paralysis following succinylcholine administration. The clinical management of all four cases was facilitated by monitoring the train-of-four stimulus. All patients showed marked "fade" of the train-of-four ratio, the initial ratios of the fourth to the first twitches being 50 per cent or less, indicating variable degrees of nondepolarizing neuromuscular blockade. Reversal of paralysis with anticholinesterase agents was completely successful in three cases, but only partially effective in the fourth because of the probable presence of a mixture of both depolarizing block and nondepolarizing block. In such a situation, caution in the interpretation of the train-of-four ratio is necessary, since this test measures only the nondepolarizing component of the block. Whether or not reversal with anticholinesterase drugs is attempted, clinical estimates of neuromuscular function, such as head lift, vital capacity, and inspiratory force, must be carefully correlated with train-of-four values. If reversal is attempted, the brief action of edrophonium provides a useful clinical trial.

Adolescent↗
PubMedDate not supplied

Aortic atresia with interruption of the aortic arch and an aortopulmonary fistulous tract: case report.

We present a case of interruption of the aortic arch (IAA) in association with aortic atresia. A pulmonary artery to ascending aorta fistulous channel at the level of the sinuses of Valsalva of the pulmonary artery was present and supplied the ascending aorta and coronary arteries. The communication had a significant length, so embryologically it is not an aortopulmonary window. There have been only three reported cases in the literature of IAA with aortic atresia; in none was a pulmonary artery to ascending aorta fistulous tract present.

Aorta↗