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Biomedical subjects

M D McGoon

Publications and source records attributed to M D McGoon.

At least 37 records · Page 2Linked to original sources
PubMed1994

Survival in primary pulmonary hypertension with long-term continuous intravenous prostacyclin.

OBJECTIVE: To evaluate the effects of long-term-intravenous infusion of prostacyclin on exercise capacity, hemodynamics, and survival in patients with primary pulmonary hypertension. DESIGN: Open, multicenter, uncontrolled trial. SETTING: Four referral centers. PATIENTS: 18 patients with primary pulmonary hypertension: 1 New York Heart Association (NYHA) class II patient, 13 NYHA class III patients, and 4 NYHA class IV patients. INTERVENTIONS: Continuous intravenous prostacyclin administered by portable infusion pumps. All patients were treated with anticoagulant agents. MEASUREMENTS AND MAIN RESULTS: With the 6-minute walk used to evaluate exercise capacity, patients could walk on average more than 100 meters farther after prostacyclin therapy was initiated (distance at 6 months, 370 +/- 119 meters compared with 264 +/- 160 meters at baseline; P < 0.001; distance at 18 months, 408 +/- 138 meters; P = 0.02 compared with baseline). Hemodynamics were improved at 6 months: The cardiac index increased 18% (95% CI, 0.1% to 36.7%; P = 0.02), and mean pulmonary artery pressure and total pulmonary resistance decreased 9% (CI, 1.4% to 15.7%; P = 0.03) and 26% (CI, 6.1% to 46.3%; P = 0.02), respectively, compared with baseline. The improvements in cardiac index and total pulmonary resistance were maintained at 12 months (27% increase [CI, 1.3% to 51.9%; P = 0.05] and 32% decrease [CI, 9.7% to 53.6%; P = 0.02] compared with baseline, respectively). Survival was improved in NYHA class III and IV patients who received continuous prostacyclin (n = 17; follow-up, 37 to 69 months) when compared with historical controls who received standard therapy (National Institutes of Health Primary Pulmonary Hypertension Registry, n = 31, P = 0.045). Kaplan-Meier estimates of 1-, 2-, and 3-year survival rates for the patients treated with prostacyclin were 86.9%, 72.4%, and 63.3%, respectively, compared with 77.4%, 51.6%, and 40.6% for the historical control group (hazard ratio, 2.9 [CI, 1.0 to 8.0; P = 0.045]). Serious complications attributable to the drug and delivery system included two deaths and seven episodes of nonfatal sepsis in three patients. CONCLUSIONS: Continuous intravenous prostacyclin resulted in sustained clinical and hemodynamic improvement and probably in improved survival in patients with severe primary pulmonary hypertension. Despite potentially serious complications, long-term prostacyclin may be especially helpful in seriously ill patients awaiting transplantation.

Adult↗
PubMed1993

Long-term outcome in patients undergoing surgical repair of tetralogy of Fallot.

BACKGROUND: Although corrective surgery for tetralogy of Fallot has been available for more than 30 years, the occurrence of late sudden death in patients in whom surgery was apparently successful remains worrisome. METHODS: We studied long-term survival among 163 patients who survived 30 days after complete repair of tetralogy of Fallot, examining follow-up hospital records and death certificates when relevant. RESULTS: The overall 32-year actuarial survival rate among all patients who survived surgery was 86 percent, as compared with an expected rate of 96 percent in a control population matched for age and sex (P < 0.01). Thirty-year actuarial survival rates were calculated for the patient subgroups. The survival rates among patients less than 5 years old, 5 to 7 years old, and 8 to 11 years old were 90, 93, and 91 percent, respectively--slightly less than the expected rates (P < 0.001, P = 0.06, and P = 0.02). Among patients 12 years old or older at the time of surgery, the survival rate was 76 percent, as compared with an expected rate of 93 percent (P < 0.001). The performance of a palliative Blalock-Taussig shunt procedure before repair, unlike the performance of a Waterston or Potts shunt procedure, was not associated with reduced long-term survival, nor was the need for a trans-annular patch at the time of surgery. Independent predictors of long-term survival were older age at operation (P = 0.02) and a higher ratio of right ventricular to left ventricular systolic pressure after surgery (P = 0.008). Late sudden death from cardiac causes occurred in 10 patients during the 32-year period. CONCLUSIONS: Among patients with surgically repaired tetralogy of Fallot, the rate of long-term survival after the postoperative period is excellent but remains lower than that in the general population. The risk of late sudden death is small.

Analysis of Variance↗
PubMed1993

The Dotter retriever and pigtail catheter: efficacy in extraction of chronic transvenous pacemaker leads.

Several techniques exist for percutaneous extraction of chronic pacemaker leads. To establish the efficacy of the Dotter retriever and pigtail catheter, we reviewed the removal of 59 endocardial pacemaker leads in 42 patients (mean age 71 years). The mean duration of lead implantation was 44 months (range 1-169 months). Thirty-two leads were withdrawn with simple traction alone, and five leads were abandoned when traction failed. The remaining 22 leads were manipulated with a Dotter retriever or pigtail catheter, or both. Twelve leads were dislodged from the endocardium with simple traction (10) or with traction transmitted through an entwining pigtail catheter (2), but they could not be fully withdrawn. Eleven of these leads (92%) were then successfully extracted with the Dotter retriever. Seven of the remaining 10 leads were successfully dislodged and removed by the Dotter retriever. Overall, 9 of 12 leads (75%) that could not be dislodged from the endocardium with simple traction were removed with a Dotter retriever or pigtail catheter, or both. Three patients in whom no catheter method worked required thoracotomy for removal of infected leads. No complications resulted from use of the Dotter retriever or pigtail catheter. We conclude that the Dotter retriever and pigtail catheter have moderate efficacy for dislodging chronic endocardial leads. Once mobilized, however, the leads can be withdrawn with great success with the Dotter retriever. Newer technology should not result in the abandonment of this proven technique.

Adolescent↗
PubMed1992

Techniques of immunosuppression after cardiac transplantation.

Modulation of the normal immune response is the major challenge for successful organ transplantation. Cardiac allograft rejection is primarily the result of activation of T cells. Most currently used immunosuppressive agents mainly affect the T-cell-mediated limb of the immune system. Immunosuppressive strategies can be considered to have three goals: (1) prophylaxis against rejection early after cardiac transplantation, (2) long-term maintenance prophylaxis, and (3) treatment of acute rejection. The extent of immunosuppression needed varies with the time after transplantation and the rejection profile of the individual patient. The goal is to provide sufficient immunosuppression to retard rejection without causing undesirable side effects, including infection and neoplasms.

Drugs, Investigational↗
PubMed1991

Antitachycardia pacemaker treatment of postoperative arrhythmias in pediatric patients.

An automatic antitachycardia pulse generator (Intertach 262-12) was implanted in each of six pediatric patients (mean age, 10 years) with drug-resistant and persistent postoperative supraventricular arrhythmias. Four had bradycardia-tachycardia syndrome, two after a Mustard procedure for transposition of the great arteries, one after a Senning procedure for the same anomaly, and one after a Fontan procedure for univentricular heart with transposition of the great arteries. Of the two remaining patients, one had atrial flutter after a modified Fontan procedure for univentricular heart and one had intra-atrial reentry tachycardia after a modified Fontan procedure for double-outlet right ventricle with pulmonary stenosis. During a mean follow-up interval of 31 months after implantation, pacemakers were activated on multiple occasions and functioned appropriately in all six patients. Complications necessitated six invasive interventions in three patients: erosion or infection of the system, adaptor fracture, and connector block fracture on one occasion each and lead dislodgment on three occasions. Four of the six patients continued to take drugs at the end of this study; however, all patients had their drug therapy reduced and one was taking digoxin only. The number of hospital admissions decreased after implantation. Despite a number of technical challenges, this newer multiprogrammable antitachycardia pacemaker appears to be a valuable addition to the treatment of refractory postoperative supraventricular tachyarrhythmias in pediatric patients.

Adolescent↗
PubMed1991

Noninvasive assessment of cardiac risk in insulin-dependent diabetic patients being evaluated for pancreatic transplantation using thallium-201 myocardial perfusion scintigraphy.

We examined the value of thallium-201 myocardial perfusion scintigraphy in noninvasive assessment of cardiac risk in 36 insulin-dependent (type 1) diabetic patients being evaluated for pancreas or combined pancreas/kidney transplantation. An extensive cardiovascular evaluation including electrocardiogram was performed in all patients, and most patients were also evaluated by two-dimensional and Doppler echocardiography. Exercise thallium studies were performed in 31 patients. Five patients were unable to exercise and underwent dipyridamole-thallium study. The thallium images were abnormal in 12 patients, 10 of whom underwent coronary arteriography. Significant coronary artery disease was found in 7 of these patients. Nineteen patients underwent pancreatic (3 patients) or pancreato-renal (16) transplantation without any occurrence of cardiac death or nonfatal myocardial infarction peri-operatively or on follow-up ranging from 7 months to 21 months. In contrast, 3 cardiac events occurred in 12 patients not approved for transplantation, each of whom had an abnormal thallium study exhibiting significant ischemia. Resting left ventricular global and regional function was not helpful in determining perioperative risk. Thus, thallium-201 myocardial perfusion scintigraphy may be useful in identifying diabetic patients at low risk for pancreas transplantation and may obviate the need for routine coronary angiography in these patients.

Adult↗
PubMed1990

Long-term outcome after surgical repair of isolated atrial septal defect. Follow-up at 27 to 32 years.

BACKGROUND: Atrial septal defects have been surgically correctable for more than 30 years. The long-term survival rates among patients treated in the early era of cardiac surgery are poorly documented, but such data are of critical importance to the future medical care, employability, and insurability of these patients. METHODS: To determine the natural history of surgically corrected atrial septal defects, we studied all 123 patients who underwent repair of an isolated defect (ostium secundum or sinus venosus) at the Mayo Clinic between 1956 and 1960, 27 to 32 years after the procedure. The follow-up status of all patients was determined by written questionnaires and telephone interviews. Hospital records and death certificates were obtained if interim hospitalization or death had occurred. RESULTS: The overall 30-year actuarial survival rate among survivors of the perioperative period was 74 percent, as compared with 85 percent among controls matched for age and sex. The perioperative mortality was 3.3 percent (four deaths). Actuarial 27-year survival rates among patients in the younger two quartiles according to age at operation (less than or equal to 11 years and 12 to 24 years) were no different from rates among controls--97 percent and 93 percent, respectively. In the two older quartiles (25 to 41 years and greater than 41 years), 27-year survival rates were significantly less (P less than 0.001)--84 percent and 40 percent, respectively--than in controls (91 and 59 percent). Independent predictors of long-term survival according to multivariate analysis were age at operation (P less than 0.0001) and systolic pressure in the main pulmonary artery before operation (P less than 0.0027). When repair was performed in older patients, late cardiac failure, stroke, and atrial fibrillation were significantly more frequent. CONCLUSIONS: Among patients with surgically repaired atrial septal defects, those operated on before the age of 25 have an excellent prognosis, but older patients require careful, regular supervision.

Actuarial Analysis↗
PubMed1989

The feasibility of utilizing the systolic pre-ejection interval as a determinant of pacing rate.

Rate-modulated pacing modes adjust the stimulus rate by responding to sensed alterations in physiologic indexes of metabolic demand. This study was designed to determine whether right ventricular pre-ejection interval, measured in patients by a prototype pacemaker system capable of tracking intraventricular volume, changes predictably with exercise and, if so, whether it can be used in an algorithm to vary heart rate appropriately. This system utilizes intraventricular electrical impedance measurements of injected microampere currents to determine intracavitary volume changes. Five pacemaker-dependent patients underwent temporary insertion of a tripolar electrode connected to an external device that sensed cardiac signals, generated an impedance wave form and produced stimuli at rates dependent on pre-ejection interval. Pre-ejection interval did not change as a result of variations in pacing rate itself (347 +/- 41 ms at 70 beats/min versus 321 +/- 19 ms at 130 beats/min), but consistently decreased during graded exercise (by 23% from baseline). During rate-modulated pacing based on pre-ejection interval, heart rate significantly increased during exercise compared with ventricular demand pacing (by 46 +/- 6 versus 7 +/- 6 beats/min, respectively), and increased appropriately during burst exercise. Thus, the pre-ejection interval appears to be a specific, reliable physiologic determinant of pacing rate during exertion, which may be applicable in implantable rate-modulated pacemakers.

Adult↗
PubMed1989

Failure of atrial natriuretic factor to increase with volume expansion in acute and chronic congestive heart failure in the dog.

It remains unclear whether the levels of atrial natriuretic factor (ANF) observed in chronic CHF are appropriate for the magnitude of elevations in atrial pressures. Specifically, it is not known whether acute increases in atrial pressure in CHF can result in further significant increases in circulating ANF. The present study was designed to test the hypothesis that in chronic CHF there is an attenuated relation between circulating ANF and atrial pressure such that the heart is unable to respond to further increases in atrial pressure with appropriate increases in ANF. Cardiovascular hemodynamics and plasma levels of ANF were measured at baseline and after rapid right ventricular pacing (RRVP) to produce acute (n = 10, 25 minutes RRVP) and chronic (n = 7, 14-16 days RRVP) CHF. Acute saline volume expansion was then performed in each group to determine the response of circulating ANF to acute increases in atrial pressure in both acute and chronic CHF. In chronic CHF, right atrial pressure was much higher than in acute CHF (8.5 +/- 0.9 vs. 3.4 +/- 1.3 mm Hg, p less than 0.05); however, circulating ANF was not greater in chronic as compared with acute CHF (385 +/- 73 vs. 500 +/- 89 pg/ml), which is consistent with an attenuated release of ANF in chronic CHF. In response to volume expansion, right atrial pressure increased in both acute (3.4 +/- 1.3 to 12.1 +/- 7 mm Hg) and chronic (8.5 +/- .9 to 13.3 +/- 1.0 mm Hg) CHF.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1988

Chronic aortic regurgitation: indications for operation--1988.

Timing of operation in a patient with severe aortic regurgitation is a difficult and controversial decision, especially when the patient is asymptomatic or minimally symptomatic. A rational decision can be made when the pathophysiologic features of aortic regurgitation and the natural history of medically treated patients are understood and the benefits and risks associated with aortic valve replacement are known. Proper interpretation of the literature involving echocardiography and nuclear cardiology is essential, as is consideration of the constantly changing surgical techniques and results. Aortic valve replacement should be recommended for those patients with chronic aortic regurgitation who are severely symptomatic (New York Heart Association Functional Class III or IV), in order to ameliorate symptoms and increase longevity. In asymptomatic or minimally symptomatic patients, close continued serial follow-up is necessary in order to detect the onset of resting left ventricular dysfunction and to recommend the optimal timing for surgical intervention.

Aortic Valve Insufficiency↗
PubMed1988

Long-term outcome of patients undergoing surgical repair of isolated pulmonary valve stenosis. Follow-up at 20-30 years.

In a group of 191 consecutive patients who underwent operation at the Mayo Clinic for isolated pulmonary valve stenosis between 1956 and 1967, late results were excellent. In patients surviving operation before the age of 21 years, long-term survival was similar to that in an age- and sex-matched control population. In the other patients, late survival and functional status were good, but survival was poorer than in the control population. This late attrition, most likely due to the sequelae of long-standing right ventricular hypertrophy, suggests the need for continued surveillance. Late sudden death occurred in only three patients, between 10 and 21 years postoperatively. The finding of normal life expectancy for such patients who survive operation before age 21 is important for actuarial purposes and for the patients' career and employment plans.

Adolescent↗
PubMed1987

The natural history of lone atrial fibrillation. A population-based study over three decades.

From 1950 to 1980, 3623 patients from Olmsted County, Minnesota, were found to have atrial fibrillation. Ninety-seven of these patients (2.7 percent), who were 60 years old or younger at diagnosis, had lone atrial fibrillation (atrial fibrillation in the absence of overt cardiovascular disease or precipitating illness), and their data were reviewed to determine the incidence of thromboemboli. Twenty of these patients (21 percent) had an isolated episode of atrial fibrillation, 56 (58 percent) had recurrent atrial fibrillation, and 21 (22 percent) had chronic atrial fibrillation. The total follow-up period was 1440 person-years, with a mean of 14.8 years per patient. The mean age at diagnosis was 44 years. Nineteen cardiovascular events occurred in 17 patients; 4 patients had strokes thought to be due to emboli from atrial fibrillation, and 4 had myocardial infarctions without overt evidence of previous coronary artery disease. The probability of survival at 15 years was 94 percent among the patients with lone atrial fibrillation. At 15 years, 1.3 percent of the patients had had a stroke on a cumulative actuarial basis. On an actuarial basis, there was no difference in survival or in survival free of stroke among the patients with the three types of lone atrial fibrillation (i.e., isolated, recurrent, and chronic). We conclude that lone atrial fibrillation in patients under the age of 60 at diagnosis is associated with a very low risk of stroke. This suggests that routine anticoagulation may not be warranted.

Adolescent↗
PubMed1987

Acute hemodynamic response to the S2-serotonergic receptor antagonist, ketanserin, in patients with primary pulmonary hypertension.

The acute hemodynamic effect of intravenous ketanserin, an S2-serotonergic receptor antagonist, was evaluated during right heart catheterization in 20 patients with primary pulmonary hypertension. Pulmonary and systemic vascular resistance and pressure and cardiac output were measured before and after infusion of low and high dose ketanserin. A small decrease in pulmonary vascular resistance occurred after high dose drug infusion (28.4 to 25.0 U X m2; P less than 0.001), and mean pulmonary arterial pressure was unchanged. Decreases in systemic arterial pressure (91.9 to 85.9 mm Hg; P less than 0.0005) and systemic resistance (46.2 to 38.6 U X m2; P less than 0.001) were more pronounced. Cardiac index increased significantly (2.16 to 2.42 l/min/m2; P less than 0.01) due to reduced ventricular afterload. This study indicates that ketanserin has a small pulmonary vasodilating effect in primary pulmonary hypertension of doubtful clinical significance, similar to conventional vasodilators.

Adolescent↗
PubMed1987

Noninvasive conversion of a fixed-rate demand pacemaker to activity mode: a method for assessing the clinical effect of rate-responsiveness.

Some patients with fixed-rate demand pacemakers may benefit from conversion to a rate-responsive pacing system. In this report, we describe a technique by which the effect of rate-responsive pacing can be assessed before replacing the pacemaker system. An externally positioned activity-mode physiologic pulse generator was used to drive a previously implanted ventricular demand pacemaker programmed to the triggered mode. Comparison of exercise capacity under both conditions suggested a substantial benefit from rate-responsiveness.

Aged↗