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D C Sabiston

Publications and source records attributed to D C Sabiston.

At least 55 records · Page 3Linked to original sources
PubMed1985

Linearity of the Frank-Starling relationship in the intact heart: the concept of preload recruitable stroke work.

The Frank-Starling relationship generally has been examined with filling pressure as the index of preload, resulting in a curvilinear function that plateaus at higher filling pressures. To investigate this relationship further in the intact heart, 32 dogs were chronically instrumented with left ventricular and pleural micromanometers and with regional (10 dogs) or global (22 dogs) ultrasonic dimension transducers. Seven days after implantation, left ventricular pressure and regional or global dimensions were recorded in the conscious state. After autonomic blockade, preload was varied by vena caval occlusion. Myocardial function was assessed by calculating regional or global stroke work, and preload was measured as end-diastolic segment length or chamber volume. The relationship between stroke work and either end-diastolic segment length or chamber volume (termed the preload recruitable stroke work relationship) was highly linear in every study (mean r = .97) and could be quantified by a slope (MW) and x-intercept (LW). Previous nonlinear relationships between stroke work and filling pressure seemed to reflect the exponential diastolic pressure-volume curve. Over the physiologic range of systolic arterial pressures produced by infusion of nitroprusside or phenylephrine, no significant change was observed in MW or LW in the normal dog. Calcium infusion increased both regional and global MW by 71 +/- 19% and 65 +/- 9%, respectively (p less than .02), with no significant change in LW. To normalize for ventricular geometry and heart rate, stroke work was computed from circumferential stress-strain data and converted to myocardial power output, which was then plotted against end-diastolic circumferential strain. This relationship also was highly linear, and the slope, Mmp (mW/cm3 of myocardium), is proposed as a potential measure of intrinsic myocardial performance independent of loading, geometry, and heart rate.

Animals↗
PubMed1985

Radiographic findings in pulmonary hypertension from unresolved embolism.

Pulmonary artery hypertension with chronic pulmonary embolism is an uncommon entity that is potentially treatable with pulmonary embolectomy. Although the classic radiographic features have been described, several recent investigators report a significant percentage of these patients with normal chest radiographs. In a series of 22 patients, no normal radiographs were seen. Findings included cardiomegaly (86.4%) with right-sided enlargement (68.4%), right descending pulmonary artery enlargement (54.5%), azygos vein enlargement (27.3%), mosaic oligemia (68.2%), chronic volume loss (27.3%), atelectasis and/or effusion (22.7%), and pleural thickening (13.6%). Good correlation with specific areas of diminished vascularity was seen on chest radiographs compared with pulmonary angiograms.

Adult↗
PubMed1985

Electron microscopy in selection of patients with small cell carcinoma of the lung for medical versus surgical therapy.

Fifty-one cases of small cell carcinoma of the lung were studied by electron microscopy in order to determine if ultrastructural subsets could be found and if these subsets predicted clinical behavior. All of these cases were considered bona fide small cell carcinoma of the lung by light microscopy. Tumors with ultrastructural features of epithelial differentiation were defined by the presence of well-formed, classic desmosomes joining adjacent cells and by additional features of squamous or glandular differentiation. Thirty-one tumors (60%) were considered "typical oat cell" by electron microscopy and 20 (40%) showed features of epithelial differentiation. Fifteen (75%) tumors with epithelial features were considered operable and nine (45%) were resected with curative intent. In contrast, 26 (84%) tumors considered typical oat cell by electron microscopy presented with extensive metastatic disease. The cancer-free 5-year actuarial survival rate of patients whose tumors showed features of epithelial differentiation was 25%. The actuarial survival rate of nine patients who underwent resection of tumors with epithelial features was 38% at 5 years. Only one patient whose tumor was considered typical of oat cell carcinoma by electron microscopy survived 5 years. Our current recommendation is to remove all clinically resectable pulmonary neoplasms with the expectation that these localized small cell tumors are likely to show epithelial features by electron microscopic analysis.

Carcinoma, Small Cell↗
PubMed1985

Surgical management of chronic pulmonary embolism.

Recurrent pulmonary emboli ultimately may produce respiratory insufficiency, severe hypoxemia, and progressive pulmonary hypertension. In many patients this syndrome is silent in its initial phases, and when thrombophlebitis is present it is often unresponsive to anticoagulant therapy. Unless pulmonary embolectomy is undertaken, most of these patients characteristically succumb with severe respiratory insufficiency. Twenty-five patients with this syndrome have been evaluated at the Duke University Medical Center, and 14 were selected for elective pulmonary embolectomy for relief of severe and incapacitating pulmonary insufficiency. In each patient preoperative pulmonary scans and arteriography demonstrated a high degree of vascular occlusion. The obstructing lesions affected both lungs in the majority of patients. Bronchial arteriography was found to be a very valuable method for demonstrating patency of the pulmonary arteries distal to occluding lesions by retrograde filling through collateral vessels joining the bronchial and pulmonary circulations. Preoperatively radionuclide angiocardiography revealed severe right ventricular dysfunction with significantly depressed ejection fractions at rest and during exercise. Retrograde pulmonary arterial flow as shown by selective bronchial arteriography was excellent in ten patients, fair in three, and absent in one. Long term follow-up indicated a clear relationship between the magnitude of arterial backflow at the time of embolectomy and the degree of clinical improvement. There were two perioperative deaths, one from massive reperfusion pulmonary hemorrhage and another from intractable right ventricular failure. Eleven patients with this syndrome were unsuitable candidates for embolectomy and of these, nine had severe distal emboli diffusely spread in the small pulmonary arteries and not amenable to direct removal. One patient had severe right ventricular failure with extreme pulmonary hypertension (145/45 mmHg) and another was massively obese with severe congestive heart failure and expired in the hospital a week later. In this group of 11 patients, three succumbed and most of the others are currently totally debilitated at rest (NYHA Class IV). Long-term follow-up of the surgically managed patients (1 to 15 years) shows that ten patients improved from NYHA functional Class IV to either I or II, another patient from Class III to Class I, and a final patient was only minimally improved.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Noninvasive assessment of exercise cardiac function before and after pectus excavatum repair.

Surgical correction of pectus excavatum frequently results in subjective improvement of exercise tolerance. Whether or not cardiac function improves after repair remains controversial and has primarily been limited to isolated case reports. The purpose of this investigation was to assess changes in cardiac function during rest and exercise associated with the surgical correction of this deformity. First-pass radionuclide studies during upright rest and bicycle exercise were performed on 13 patients before and at least 6 months after pectus excavatum repair. Operation did not change left ventricular ejection fraction or cardiac index at rest or during exercise. However, the left ventricular end-diastolic volume index and stroke volume index increased at rest after surgical correction. The estimated resting right ventricular end-diastolic volume also increased markedly after operation and was associated with a decrease in right ventricular ejection fraction. These data show no limitation in exercise cardiac function that could be relieved by pectus repair. However, the increase in right and left ventricular volume after operation suggests that some cardiac compression is relieved by operative repair.

Adolescent↗
PubMed1985

The effects of coronary revascularization on left ventricular function in ischemic heart disease.

Although it is well established that coronary revascularization can reverse exercise-induced ischemic dysfunction, the effects on resting ventricular performance are controversial. From a group of 183 patients receiving surgical therapy for ischemic heart disease, 166 underwent bypass graft arteriography at an average of 7 to 14 days postoperatively. In 149 patients, satisfactory preoperative and postoperative biplane left ventriculograms were obtained. Regional wall motion was assessed by the 100 segment method of Sheehan and Dodge, and a perioperative change in shortening greater than 2 standard deviations of normal variability over 20 or more adjacent segments was considered significant. Ninety-five patients had stable or progressive angina, 88 had medically refractory unstable angina, 155 were in New York Heart Association Class IV, and 37 had a preoperative left ventricular ejection fraction of less than 0.4. Myocardial integrity was preserved with crystalloid cardioplegia and topical hypothermia. Seven hundred ninety-eight bypass grafts were performed (522 vein grafts and 276 mammary artery grafts), and 13 patients had concomitant left ventricular aneurysmectomy. Hospital mortality was 2.2%. The overall early graft patency rate was 95.9% (93.7% for vein grafts and 100% for mammary arteries). Only one patient had a decrement in regional wall motion, and 51 (37%) had significant postoperative improvement (27 in the unstable angina group and 24 in the stable angina group); in the patients with improved regional wall motion, ejection fraction increased by an average of 0.18 (p less than 0.01). Ejection fraction also improved after aneurysmectomy, and the increment seemed to result from both a reduction in end-diastolic volume and improved regional wall motion. Thus, reversible ischemic myocardial dysfunction appears to be common in the general population of patients undergoing coronary artery bypass grafting; 40% of patients with unstable angina and 34% of those with stable angina can be expected to have improved regional wall motion after successful revascularization. Finally, ventricular aneurysm resection significantly enhances left ventricular performance as assessed by ventriculographic ejection fraction.

Aged↗
PubMed1984

Experimental and clinical use of the YAG laser in the management of pulmonary neoplasms.

Animal experiments were performed with evaluation of the use of the neodymium-YAG (yttrium-aluminum-garnet) laser in the trachea, bronchi, and pulmonary parenchyma. Histologic evaluation of incisions into the lung was assessed by multiple sections over a 5-week period and comparisons were made of incisions closed with chronic catgut or coagulated with electric cautery or by the laser. These studies indicated that the laser is more effective in controlling parenchymal bleeding and air leaks than either the cautery or chromic catgut and produces less local tissue reaction. The Nd-YAG laser has been used clinically to treat patients with inoperable obstructing and bleeding carcinomas of the trachea and main bronchi to open the involved airway and to restore pulmonary function. Fifteen patients have had 26 treatments using the Nd-YAG laser. Total laser time was limited to 15 minutes with 0.5-second pulses of 50 to 80 watts being delivered via the fiberoptic and straight bronchoscope as indicated. It is extremely effective in controlling hemoptysis from recurrent endobronchial lesions, and obstructing lesions in the trachea and main stem bronchus can be treated quite successfully with excellent palliation. It is apparent that continued clinical use of the Nd-YAG laser as palliative therapy for bleeding and obstructing tumors of the tracheobronchial tree is indicated and expanded use at the time of thoracotomy to control lung parenchymal bleeding and air leaks should be considered in the future.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1984

The physiology of external cardiac massage: high-impulse cardiopulmonary resuscitation.

In intact chronically instrumented dogs, left ventricular dynamics were studied during cardiopulmonary resuscitation (CPR). Electromagnetic flow probes measured cardiac output and coronary blood flow, ultrasonic transducers measured cardiac dimensions, and micromanometers measured left ventricular, right ventricular, aortic, and intrathoracic pressures. The dogs were anesthetized with morphine, intubated, and fibrillated by rapid ventricular pacing. Data were obtained during manual external massage with dogs in the lateral and supine positions. Force of compression was varied from a peak intrathoracic pressure of 10 to 30 mm Hg, and compression rate was varied from 60 to 150/min. Increasing force of compression increased stroke volume up to a peak intrathoracic pressure of approximately 20 mm Hg, beyond which stroke volume remained constant or declined. Stroke volume appeared to result primarily from direct transmission of manual compression force to the heart rather than from positive intrathoracic pressure because peak cardiac or vascular pressures or the change in these pressures were consistently two to four times greater than the corresponding intrathoracic pressures during manual compression. With increasing compression rate, stroke volume remained relatively constant, and total cardiac output increased significantly: 425 +/- 92 ml/min at 60/min, 643 +/- 130 ml/min at 100/min, and 975 +/- 219 ml/min at 150/min (p less than .05). Left ventricular dimensions decreased minimally at higher manual compression rates. In four patients undergoing CPR, systolic and diastolic arterial blood pressure increased with faster compression rates, correlating well with data obtained in the dog. Dynamic coronary blood flow in canine experiments decreased to zero or negative values during compression. Antegrade coronary flow occurred primarily during noncompression periods and seemed to be related to diastolic aortic perfusion pressure; coronary flow at a compression rate of 150/min averaged 75% of control. Therefore stroke volume and coronary blood flow in this canine preparation were maximized with manual chest compression performed with moderate force and brief duration. Increasing rate of compression increased total cardiac output while coronary blood flow was well maintained. Direct cardiac compression appeared to be the major determinant of stroke volume during manual external cardiac massage.

Animals↗
PubMed1984

The electrophysiologic effects of discrete cryosurgery for the treatment of supraventricular tachycardia due to AV nodal reentry.

The electrophysiologic effects of multiple cryosurgical lesions along the circumference of Koch's triangle were evaluated as a treatment of AV nodal reentrant tachycardia in 31 dogs. These animals were divided into a control group (n = 8) and a cryosurgical group (n = 23), and were studied using incremental atrial pacing and programmed atrial premature stimulation. In the cryosurgical group, significant prolongation of AV nodal conduction time, initiation of Wenckebach periodicity at a slower atrial pacing rate, and an increase in the functional refractory period of the AV node were documented postoperatively. In contrast, there were no significant differences between preoperative and postoperative AV node conduction characteristics in the control group. Four dogs in which the effective refractory period of the AV node could be measured showed an increase of 28-104 msec following cryosurgery. In 2 dogs, discontinuous conduction curves (i.e., dual AV nodal pathways) were demonstrated preoperatively. Postoperatively, a uniform conduction curve was demonstrated. In conclusion, these results strongly suggest that this new cyrosurgical method is an effective surgical procedure for the interruption of the reentrant circuit responsible for AV nodal reentry while preserving AV conduction.

Animals↗
PubMed1984

Surgical treatment of chronic unresolved pulmonary embolism.

This article presents a historical review, as well as a detailed discussion of the incidence, current surgical therapy, and prognosis of chronic unresolved pulmonary embolism. In patients with pulmonary hypertension resulting from this condition, the prognosis is very poor if untreated. In general, medical therapy and anticoagulants and other pharmacologic agents have remained ineffective. In selected patients, surgical embolectomy has improved pulmonary artery pressures, hypoxemia, and functional status as well as overall survival.

Adult↗
PubMed1983

Relation between QRS changes and left ventricular function after coronary artery bypass grafting.

Preoperative and serial postoperative electrocardiograms (ECGs) were reviewed in 104 patients undergoing rest and exercise radionuclide angiocardiography before and 1 to 12 months after coronary artery bypass grafting (CABG). Five patient groups were defined by ECG findings before and after CABG: Group I--normal ECG before and no ECG change after CABG; Group II--prior myocardial infarction by ECG before but no QRS change after CABG; Group III--all patients with a minor QRS change (less than 0.04-second Q wave, loss of R-wave amplitude) after CABG; Group IV--all patients with a major QRS change (greater than or equal to 0.04-second Q wave) after CABG; Group V--all patients without new Q waves or loss of R-wave amplitude but with a major QRS change (conduction disturbance) after CABG. Mean resting ejection fraction changed little after CABG in all groups, although the 0.03 increase in Group I was significant (p less than 0.05). Group IV had the largest decrease in resting ejection fraction after CABG (0.04), but this was not statistically significant. Mean exercise ejection fraction increased significantly (p less than 0.0001) in Groups I, II and III but not in Groups IV and V. QRS changes do not consistently reflect impairment of left ventricular (LV) function after CABG.

Angina Pectoris↗
PubMed1983

Trendelenburg's classic work on the operative treatment of pulmonary embolism.

The experimental and clinical observations of Trendelenburg in the operative treatment of pulmonary embolism represent a landmark in the history of surgery. The original reports of his carefully planned and performed studies in the experimental laboratory are reviewed, along with the unusually cogent clinical descriptions of this master surgeon. Trendelenburg's impressive grasp of the fundamental aspects of the pathophysiology of pulmonary embolism emphasizes the importance of a close analysis of the original communications in order to appreciate these facts fully.

Germany↗
PubMed1983

Early assessment of rest and exercise left ventricular function following coronary artery surgery.

Radionuclide assessment of rest and exercise left ventricular function was performed in 14 patients before, eight days after, and three months after coronary artery bypass grafting (CABG). Resting function was unaltered after operation, although mild increases in heart rate and end-diastolic volume were observed on the eighth postoperative day. In contrast, exercise function was significantly improved at both postoperative time periods. Exercise ejection fraction was 0.54 +/- 0.10 before operation, 0.73 +/- 0.12 at eight days, and 0.64 +/- 0.13 at three months. Before CABG, the exercise-induced increase in stroke volume was achieved by an increase in end-diastolic volume, whereas eight days after CABG this increase was achieved by an increase in contractility (systolic blood pressure/end-systolic volume). By three months, both contractility and end-diastolic volume increased with exercise. Thus, improvement in left ventricular function during exercise can be documented as early as eight days after coronary revascularization. This change may be less pronounced after three months of convalescence, but considerable improvement in ventricular function persists compared to preoperative assessment.

Aged↗