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Biomedical subjects

R B Karp

Publications and source records attributed to R B Karp.

At least 109 records · Page 6Linked to original sources

Long-term patency of saphenous veins for coronary bypass grafting.

The patency of 871 aortocoronary saphenous vein grafts in 438 patients was evaluated for a mean (+/- SEM) of 12.1 +/- 0.3 months after operation. Second studies were performed in 62 patients (134 grafts) at a mean of 42 +/- 1.3 months postoperatively (range, 13 to 61 months). The 1-year patency rate was 79.4% and increased from 76% for 546 grafts placed in 1970-1973 (Period I) to 85% for 325 grafts in 1974-1976 (period II) (P = 0.001). Overall patency was highest (82%) for grafts to the anterior descending system and lowest (76%) for the right system. These patency rates also increased between periods I and II from 79 to 88% (P < 0.05) for the anterior descending and 72 to 83% (P < 0.05) for the right system. For 47 right coronary arteries having associated distal manual endarterectomy, the graft patency rate was 62% vs 78% for those not endarterectomized (P < 0.05). Of 116 grafts patent at the initial study, five were occluded at the second study, a late failure rate of 3.7% and a mean annual attrition rate of 1.7% between 12 and 42 months after operation. High-grade (> 50%) stenoses were present in three of the five grafts at initial study. Development of late stenosis was observed in two grafts (1.7%). These data document improved 1-year patency rates for grafts in period II and a low incidence of late failure and development of late stenosis for up to 61 months following operation. Continued use of saphenous vein grafts to all three coronary arterial systems appears justified.

Adult↗

Use of temporarily placed epicardial atrial wire electrodes for the diagnosis and treatment of cardiac arrhythmias following open-heart surgery.

We retrospectively assessed our experience with the use of bipolar atrial epicardial electrodes in 70 consecutive patients following open-heart surgery. These patients, representing 1 month's experience on one of our cardiac surgical services, are a random sample of our total experience with more than 6.000 patients in whom we have routinely placed such electrodes. The atrial wire electrodes were used diagnostically and/or therapeutically in 57 patients a total of 139 times. In only 13 patients were the atrial wires not used for any reason. Atrial electrograms were recorded 63 times in 34 patients, 41 times to establish a diagnosis of an arrhythmia and 22 times to confirm the diagnosis of an arrhythmia originally suspected from interpretation of a standard or monitor electrocardiogram (ECG). Atrial pacing was used to treat abnormalities of rhythm or conduction or both in 75 instances in 49 of the 70 patients. Because of their great utility in the diagnosis and treatment of arrhythmias, we conclude that routine placement of atrial wire electrodes at the time of operation is indicated regardless of the nature of the open-heart procedure or the preoperative rhythm.

Arrhythmias, Cardiac↗

Replacement of the ascending aorta and aortic valve with a composite graft: results in 25 patients.

Our experience with combined replacement of the ascending aorta and aortic valve with a composite prosthetic valve-Dacron tube graft in 25 patients from September, 1974, to December, 1976, is reviewed. The technique involves suture of the composite graft to the aortic annulus, to the aortic tissue surrounding the coronary ostia, and to the distal ascending aorta, closing the aortic wall over the graft before discontinuing cardiopulmonary bypass. Annuloaortic ectasia was the most common indication for operation (15 patients). Perfusion of the coronary arteries was used in the first 15 patients. In the remaining 20, internal and external myocardial cooling with one period of ischemic arrest (average, 67 minutes) was used. There was 1 hospital death (4%), and there have been 3 late deaths (12%) in the 27-month follow-up period. This technique appears to be applicable to most types of aneurysmal disease of the proximal ascending aorta associated with aortic valve incompetence. All aneurysmal tissue from the aortic annulus to the innominate artery is excluded, bleeding through the graft is eliminated, operative time is reduced, and the late results have been satisfactory to date.

Adult↗

Sequence of retrograde atrial activation of the human heart. Correlation with P wave polarity.

Studies were performed in 6 patients during open heart surgery to correlate the relative sequence of atrial activation with the polarity of the retrograde P wave in electrocardiographic leads II, III, and aVF. Bipolar atrial electrograms were recorded from selected sites during threshold pacing from sites low on the right side of the atrial septum which when paced resulted in the inscription of either negative or positive P waves in electrocardiograph leads II, III, and aVF. When the atria were paced from a site just anterior to the coronary sinus ostium (negative P waves), the posteroinferior left atrium was activated early and Bachmann's bundle late during the inscription of the P wave. When the atria were paced from a site 2 cm anterior to the coronary sinus ostial site (positive P waves), Bachmann's bundle was activated early during the P wave and the posteroinferior left atrium was activated relatively later. These data from man are consistent with previous studies in the canine heart. Therefore, we deduced that in man during the inscription of negative retrograde P waves in leads II, III, and aVF, atrial activation occurs primarily in a retrograde fashion. However, during the inscription of positive retrograde P waves in man, activation occurs rapidly up the interatrial septum (we believe via the anterior internodal pathway) to Bachmann's bundle, from where it then spreads in a manner similar to that which occurs during normal sinus rhythm.

Adolescent↗

Entrainment and interruption of atrial flutter with atrial pacing: studies in man following open heart surgery.

To examine the question of why the pacing rate and duration of atrial pacing are crucial factors in the successful interruption of atrial flutter, studies were performed on 30 patients in the period following open heart surgery. In each patient the diagnosis of atrial flutter was made using a pair of wire electrodes placed on the right atrial epicardium at the time of operation and brought out through the anterior chest wall. The same electrodes were used for atrial pacing. Pacing faster than the spontaneous rate of the atrial flutter which failed to interrupt the atrial flutter was associated with transient entrainment of the atrial flutter up to the atrial pacing rate. Atrial flutter was interrupted successfully when the atria were paced at a rate which was too fast for the atrial flutter to follow. This was heralded by the conversion of previously negative flutter waves to positive atrial complexes in ECG lead II. When pacing the atria at a constant rate, 2-22 seconds with a mean of 10 seconds were required to interrupt the atrial flutter.

Adult↗

Hemodynamic responses to dopamine infusion at controlled normal and low cardiac output states in the anesthetized dog.

In order to isolate the renal and pulmonary vascular effects of dopamine, we employed a dog preparation utilizing fixed venous return in order to control cardiac output at either a normal or low flow state. Dopamine infusion was carried out at doses of 8 and 16 microng/Kg./min. Heart rate, mean systemic arterial pressure, mean pulmonary artery pressure, and renal blood flow were measured. Changes in mean systemic arterial pressure, mean pulmonary artery pressure, and renal blood flow were not significant at either doses of dopamine. There was a dose-related increase in heart rate, most significant with a dose of 16 microng/Kg./min. and low cardiac output. No evidence was found to substantiate the existence of a specific dopaminergic receptor in the renal vasculature when cardiac output was controlled.

Animals↗

Bullet emboli to the pulmonary artery: a report of 2 patients and review of the literature.

Bullet embolization to the pulmonary artery is a rare event. The purpose of this study is to report our experience with 2 patients and to review the 15 patients reported in the literature, with special emphasis on a rather peculiar complication that has occurred in 4 of the 9 patients who underwent bullet embolectomy: dislodgment of the missile during the surgical procedure and migration to the down-side lung, for which a second thoracotomy was required in 3 of those patients. The usual untoward effects of foreign bodies in the vascular system were seen in this series: embolization with thrombosis, sepsis, erosion and hemorrhage, and vascular occlusion with infarction. This review suggests that operative removal of a bullet in the pulmonary artery is necessary. The operation is safe and uncomplicated if precautions are taken to prevent the missile from migrating during manipulation of the lung.

Abdominal Injuries↗

Ascending vs descending aortic dissections.

One hundred eight patients with spontaneously developing thoracic aortic dissection were seen between 1966-1973, 78 of whom had acute dissection and 30 chronic. The age (49 vs 60 yrs) and incidence of hypertension (32% vs 71%) were significantly lower in the 56 patients in whom dissection originated in ascending aorta than in the 52 patients in whom the dissection originated in the upper descending aorta. The mortality rate in medically treated patients with acute ascending aortic dissection was 88%. Cardiac tamponade was the major cause of death. The mortality rate was significantly lower in those who were treated surgically (24%). Fifteen (54%) of the patients with ascending aortic dissection and significant aortic incompetence did not have aortic valve replacement and only two subsequently (53 and 92 months later) required valve replacement. Although the initial mortality in patients with acute descending aortic dissection treated medically and surgically was similar, the long term survival rate was higher in the surgically treated group. We conclude that ascending aortic dissection and descending aortic dissection have different clinical profiles and prognoses. Immediate surgical intervention is indicated in patients with acute ascending aortic dissection. Patients with acute descending aortic dissection can be treated medically initially followed by early elective operation.

Acute Disease↗

Continuous rapid atrial pacing to control recurrent or sustained supraventricular tachycardias following open heart surgery.

A technique is described to control recurrent or sustained supraventricular tachycardia associated with rapid ventricular rates following open heart surgery. The technique utilizes a pair of temporarily implanted atrial epicardial wire electrodes to pace the heart. In one group of patients with recurrent atrial flutter and 2:1 A-V conduction, continuous rapid atrial pacing at 450 beats/min produced and sustained atrial fibrillation. The ventricular response rate immediately slowed when compared to that during atrial flutter, and if further slowing was required, it was easily accomplished by the administration of digitalis. Another group of patients with different arrhythmias (recurrent paroxysmal atrial tachycardia, sustained ectopic atrial tachycardia, or sinus rhythm with premature atrial beats which precipitated runs of atrial fibrillation) was treated with continuous rapid atrial pacing to produce 2:1 A-V block. In all instances, the continuous rapid atrial pacing suppressed the supraventricular tachycardia and maintained the ventricular response rate in a therapeutically desirable range. It was demonstrated that the technique is safe, effective, and reliable.

Adult↗

Surgical treatment for closed thoracic aortic injuries.

Eighteen patients with acute aortic tear secondary to nonpenetrating thoracic trauma and seven with chronic tears have been operated upon. Of the patients with acute injury, 28% had normal chest x-ray on admission. The diagnosis of acute aortic tear was made by aortography in all patients. Two patients died from causes unrelated to the aortic injury. In the group of 18 patients in which some method of perfusing the distal aorta was used, two developed paraplegia; in the group of 7 treated with simple aortic cross-clamping none occurred. The average aortic cross-clamp time 69 and 23 minutes, respectively, and average blood administration 3,139 and 1,700 ml., respectively. We conclude that the diagnosis of acute aortic tear cannot be reliably made on clinical grounds, and that with properly trained personnel the method of choice is usually simple aortic cross-clamping during repair.

Aorta, Thoracic↗

Evaluating techniques of myocardial preservation for aortic valve replacement: operative risk.

In a two-year period 105 patients underwent isolated aortic valve replacement without hospital death. Eighty-three patients were operated on using hypothermic ischemic arrest; 22 patients had coronary perfusion. The early postoperative cardiac performance and incidence of complications did not differ between groups, although cardiopulmonary bypass time was shorter in the ischemic arrest group. These data suggest that ischemic arrest is a satisfactory method for myocardial preservation. However, because of the low hospital mortality rate with either method, these results and those of others cannot be taken to indicate the superiority of any method of myocardial preservation.

Adolescent↗

Late stenosis of Starr-Edwards cloth-covered prostheses.

During a two-year period (August, 1971, to July, 1973) 1 Starr-Edwards Model 2400 and 135 Starr-Edwards Model 2320 aortic prostheses were inserted without postoperative antiocagulant therapy. Seven of these valves (including the Model 2400 prosthesis) have been replaced because of substantial transvalvular gradients resulting from fibrous overgrowth of the valve orifice. Symptoms associated with aortic stenosis occurred an average of nine months after the initial operation. Six patients had severe anemia (packed cell volume less than 30%) and hemolysis (serum lactic dehydrogenase greater than 900 units). Gradients across the prostheses ranged from 66 to 105 mm Hg with a mean of 87 mm Hg. One valve was size 8A, 3 were 10A, and 1 was 12A. Fibrous ingrowth was not observed in an earlier group of 23 patients receiving the Model 2310 or Model 2320 prosthesis who were placed on long-term anticoagulant therapy. These findings, coupled with a 9% incidence of thromboembolism at one year, indicate that patients having these prostheses inserted should receive long-term anticoagulant therapy.

Adult↗

P waves during ectopic atrial rhythms in man: a study utilizing atrial pacing with fixed electrodes.

Threshold bipolar pacing was performed from one of 12 selected atrial sites with temporary implanted electrodes in 69 patients following open-heart surgery in order to study P wave polarity and morphology and the P-R interval during paced ectopic atrial rhythms. A negative P wave was recorded in lead I only with pacing the left atrium and only when pacing near the left pulmonary veins. A positive bifid P wave in V1 was recorded only with left atrial pacing and only when pacing was near the inferior pulmonary veins and coronary sinus. P wave polarity and morphology were otherwise of no use in localization of the origin of the impulse in these studies. The pacing stimulus to P wave interval was found to vary between 10 and 54 msec, making the duration of the P-R interval an unreliable indicator of the site of origin of the paced impulse. Although the relation of these paced rhythms to spontaneously occurring ectopic rhythms is unclear, the previously published criteria for localizing ectopic atrial rhythms are again demonstrated to be unreliable. P wave polarity and morphology and the P-R interval are of limited value in ascertaining the origin of ectopic atrial rhythms in man.

Adult↗

Paradoxical septal motion in a patient with pulmonic stenosis.

This case will demonstrate abnormal (paradoxical) septal motion in a 31-year-old woman with an isolated pulmonary valvular stenosis. The right ventricular volume overload was exluded by the shunt series, special angiographic studies and at surgery. The echocardiographic abnormality persisted during a restudy three months after surgery.

Adult↗

Valve replacement and myocardial revascularization. Results of combined operation in 59 patients.

Fifty-nine patients (mean age 57 years) underwent aortic valve replacement or mitral valve replacement combined with saphenous vein bypass grafting (39 single, 19 double, 1 triple) between May, 1970 and January, 1974. The hospital mortality for aortic valve replacement was 4.7% (2 of 43 patients) and for mitral valve replacement 6.3% (1 of 16 patients). There was a 21% incidence of postoperative myocardial injury in the patients with aortic valve replacement and a 6.2% incidence in the patients with mitral valve replacement. Variations in operative technique and in the methods of intraoperative myocardial preservation (coronary perfusion or profound hypothermic ischemic arrest) did not affect hospital mortality or the incidence of myocardial injury. Prolonged periods of ischemic arrest (greater than 50 minutes) were not used. The late mortality for aortic valve replacement was 16.3% (seven patients) and for mitral valve replacement 25% (four patients). There was symptomatic improvement in the majority of survivors. Operative mortality rates for the combined procedures are comparable to those from our institution for valve replacement alone.

Adult↗