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Biomedical subjects

N P Madigan

Publications and source records attributed to N P Madigan.

At least 19 recordsLinked to original sources
PubMed1995

Which is the graft of choice for the right coronary and posterior descending arteries? Comparison of the right internal mammary artery and the right gastroepiploic artery.

BACKGROUND: The graft of choice for the left anterior descending coronary artery is the left internal mammary artery because of superior long-term patency. However, controversy exists regarding the graft of choice for the right coronary artery and for the posterior descending branch. METHODS AND RESULTS: Two types of pedicled arterial grafts were used for the right coronary and the posterior descending arteries in patients undergoing coronary bypass surgery between January 1991 and September 1994. Group A comprised 114 patients with a right internal mammary artery (RIMA) graft, and group B consisted of 127 patients with an in situ right gastroepiploic artery (R-GEA) graft. Mean age was 56.9 years in group A and 63.3 years in group B; 7.9% (9 of 114) and 33.9% (43 of 127) were diabetics in groups A and B, respectively. Overall mortality was 2.6% (3 deaths) for group A and 3.9% (5 deaths) for group B (P = NS). However, the prevalence of perioperative myocardial infarction in the right coronary artery distribution was significantly higher for group A (5.3%, or 6 of 114) than for group B (0.8%, or 1 of 127; P < .05), and the reoperation rate for graft failure (from 0 to 12 months after surgery) was significantly higher for the RIMA (4.4%, or 5 of 114) than for the R-GEA (0%; P < .05). Also, the prevalence of deep sternal wound infection in diabetics was significantly higher in group A (22.2%, or 2 of 9) than in group B (4.6%, or 2 of 43; P < .05). CONCLUSIONS: Our preliminary results suggest that the failure rate of the RIMA graft is significantly higher, especially if used as a pedicled graft to the posterior descending artery. The risk of sternal wound complications is greater in diabetics if both internal mammary arteries are used for grafting. Therefore, the R-GEA graft is preferred in diabetics and whenever the posterior descending artery is the target vessel.

Adult↗
PubMed1995

Myocardial revascularization using the "no-touch" technique, with mild systemic hypothermia, in patients with a calcified ascending aorta.

Modifications in the standard technique for coronary artery bypass grafting are recommended in presence of a calcified ascending aorta, to avoid clamp injury or atheroembolism. Between January 1991 and August 1994, we used a "no-touch" technique in 18 patients undergoing myocardial revascularization, who had a heavily calcified and atherosclerotic ascending aorta. Their mean age was 76.1 years (range 63 to 82 years). Cardiopulmonary bypass with mild systemic hypothermia (32 degrees C) was employed in 16 patients; 2 other patients were operated upon without cardiopulmonary bypass. The "no-touch" technique avoids all types of clamps in the aorta. No cardioplegia was given, and no grafts were anastomosed to the aorta. Fifty-two distal anastomoses (mean: 2.9 per patient) were performed, using 37 pedicled arterial grafts (22 internal mammary and 15 gastroepiploic arteries), and 15 free grafts, which were anastomosed proximally to the internal mammary artery. There were no postoperative cerebrovascular accidents. Three patients died (16.7% overall mortality): 1 died of pneumonia, one patient with a large left ventricular aneurysm died in congestive heart failure, and one patient with associated aortic insufficiency died in low cardiac output. Our experience suggests that using pedicled arterial grafts for myocardial revascularization is safe and effective to avoid clamp injury or atheroembolism in patients with a calcified aorta. Deep hypothermia is not necessary when using the "no-touch" technique.

Aged↗
PubMed1993

Acute myocardial infarction complicating urokinase infusion for total saphenous vein graft occlusion.

Saphenous vein graft occlusions have been successfully treated with extended urokinase infusions. We report a case of myocardial infarction complicating this treatment. A review of reported cases suggests that this complication may not be uncommon. The optional drug, dose, and infusion technique for intra-graft lytic therapy has not been determined. The costs, risks, and difficulty of this technique may limit its application.

Aged↗
PubMed1993

Results of coronary artery bypass grafting using multiple arterial conduits.

Between January 1991 and June 1993, a total of 128 patients underwent coronary artery bypass grafting employing multiple autologous arterial conduits, including 157 internal mammary arteries, 69 inferior epigastric arteries, 44 gastroepiploic arteries, and 72 radial artery grafts. Their mean age was 61.4 years (range 29 to 82 years). The patients were divided into 2 groups: group A, consisted of 69 patients (mean age 60.3 years), in whom multiple arterial conduits were used exclusively (no vein grafts); group B, included 59 patients (mean age 62.7 years) in whom, in addition to multiple arterial conduits, 89 saphenous vein grafts were used concomitantly. The mean number of grafts was 3.1 and 3.7, for groups A and B, respectively. The preoperative left ventricular function, and the prevalence of unstable angina, a recent myocardial infarction, and diabetes, were not significantly different between both groups. Our series included 11 "redo" operations (8 in group A, and 3 in group B). There were 6 early deaths (4.7% mortality) (1 in group A, and 5 in group B), and 4 perioperative myocardial infarctions (1 in group A, 3 in group B). During a mean follow-up of 12.9 months (range 1 to 28 months) there were no late deaths or reoperations in any group. All patients in group A are free of symptoms. In group B, 2 patients have recurrent angina, and 1 had a late myocardial infarction, in the distribution of a vein graft. A myocardial SPECT scan with exercise revealed new perfusion defects in 4 of 49 patients (1 in group A, 3 in group B), studied 1 year after surgery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

Comparative survival following permanent ventricular and dual-chamber pacing for patients with chronic symptomatic sinus node dysfunction with and without congestive heart failure.

To determine whether survival following permanent ventricular demand pacing differs from survival following permanent dual-chamber pacing in patients with symptomatic sinus node dysfunction (unexplained sinus bradycardia, subsidiary rhythms, sinus arrest, sinoatrial block, or the bradycardia/tachycardia syndrome), we followed 79 patients who received a VVI pacemaker (group 1) and 49 patients who received a DVI or DDD pacemaker (group 2) for 1 to 5 years. There was no significant difference in sex distribution, mean age, or the incidence of coronary heart disease, hypertension, valvular heart disease, diabetes mellitus, stroke, or renal failure between groups 1 and 2. Overall, the predicted cumulative survival rates at 1, 3, and 5 years were 89%, 82%, and 74%, respectively, for group 1 and 94%, 86%, and 78%, respectively, for group 2. In patients with preexistent congestive heart failure (CHF), predicted cumulative survival rates at 1, 3, and 5 years were 78%, 69%, and 57%, respectively, for group 1 (n = 23) and 90%, 83%, and 75%, respectively, for group 2 (n = 16). Five-year predicted cumulative survival was significantly lower in group 1 patients with CHF than in group 2 patients with CHF (p less than 0.03). There was no significant difference in 5-year cumulative survival rates between groups 1 and 2 in patients without CHF. The results suggest that permanent dual-chamber pacing enhances survival to a greater extent than permanent ventricular demand pacing in patients with chronic symptomatic sinus node dysfunction and CHF.

Aged↗
PubMed1986

Comparative survival after permanent ventricular and dual chamber pacing for patients with chronic high degree atrioventricular block with and without preexistent congestive heart failure.

To determine whether survival after permanent ventricular demand (VVI) pacing differs from survival after permanent dual chamber (DVI or DDD) pacing in patients with chronic high degree atrioventricular (AV) block (Mobitz type II or trifascicular block), 132 patients who received a VVI pacemaker (Group 1) and 48 patients who received a DVI or DDD pacemaker (Group 2) were followed up for 1 to 5 years. There was no significant difference in sex distribution, mean age or incidence of coronary heart disease, hypertension, valvular heart disease, diabetes mellitus, stroke or renal failure between Groups 1 and 2. Overall, the predicted cumulative survival rate at 1, 3 and 5 years was 89, 76 and 73%, respectively, for Group 1 and 95, 82 and 70%, respectively, for Group 2. In patients with preexistent congestive heart failure, the predicted cumulative survival rate at 1, 3 and 5 years was 85, 66 and 47%, respectively, for Group 1 (n = 53) and 94, 81 and 69%, respectively, for Group 2 (n = 20). The 5 year predicted cumulative survival rate was significantly lower in Group 1 patients with preexistent congestive heart failure than in Group 2 patients with the same condition (p less than 0.02). There was no significant difference in 5 year cumulative survival rate between Groups 1 and 2 for patients without preexistent congestive heart failure. The results suggest that permanent dual chamber pacing enhances survival to a greater extent than does permanent ventricular demand pacing in patients with high degree AV block and preexistent congestive heart failure.

Age Factors↗
PubMed1984

Carotid sinus hypersensitivity: beneficial effects of dual-chamber pacing.

Three types of carotid sinus (CS) syndrome have been described: cardioinhibitory, vasodepressor and mixed. For the treatment of symptomatic patients with associated significant cardioinhibition, permanent ventricular demand pacing systems are often implanted. Even with this pacing modality, some patients remain symptomatic because of continued (and at times aggravated) vasodepression. This study assesses the effects of loss of atrial preloading and orthostasis after carotid massage in patients with CS hypersensitivity. Eleven patients were studied using constant intra-arterial pressure measurements during either ventricular (VVI) or atrioventricular sequential (DVI) pacing in both supine or upright positions. The measurements performed included the magnitude of decrease in arterial blood pressure (BP), the rate of decrease of BP and the percent change in BP from baseline values. After carotid massage, all 11 patients had greater hemodynamic change with the VVI than DVI pacing mode, whether in the supine or upright position. The decreases in systolic BP were: DVI (supine) 29 mm Hg, VVI (supine) 48 mm Hg, DVI (upright) 37 mm Hg, and VVI (upright) 59 mm Hg (mean group values, p less than 0.001). The rates of decrease of systolic BP were: DVI (supine) 2.9 mm Hg/s, VVI (supine) 5.7 mm Hg/s, DVI (upright) 4.1 mm Hg/s, and VVI (upright) 8.3 mm Hg/s (mean group values, p less than 0.001). VVI pacing, particularly in the upright position, resulted in a significant increase in the incidence of patient symptoms (p = 0.03). Thus, in CS hypersensitivity, VVI pacing results in significant hemodynamic deterioration compared to DVI mode. This aggravation of the vasodepressor component results in increased patient symptoms, and therefore, DVI is the optimal pacing mode.

Adult↗
PubMed1984

Mexiletine for recurring ventricular arrhythmias: assessment by long-term electrocardiographic recordings and sequential electrophysiologic studies.

Mexiletine, an oral lidocaine-like drug, was initially thought to be effective treatment for recurring ventricular arrhythmias. Recent work has cast doubt on its efficacy. We administered mexiletine to 32 patients with chronically recurring ventricular arrhythmias. In 22 patients with no history of syncope or documented sustained ventricular arrhythmia (group 1), mexiletine was effective in only 27% (six patients) as assessed by 24-hour ambulatory ECG recordings before and during mexiletine treatment. Ten other patients had a history of syncope or documented sustained ventricular tachycardia or ventricular fibrillation. Only 10% (one patient) responded to mexiletine based on sequential electrophysiologic studies with programmed ventricular stimulation. Four of the seven patients responding to mexiletine had not received prior antiarrhythmic therapy. We conclude that mexiletine has limited efficacy in the treatment of recurring drug-refractory ventricular arrhythmias.

Adult↗
PubMed1984

Difficulty of extraction of chronically implanted tined ventricular endocardial leads.

The dislodgment rate of permanent pacing ventricular and atrial endocardial leads has significantly decreased with the incorporation of tines as a fixation device. In contrast, transvenous manual extraction of chronically implanted endocardial leads is, at times, clinically indicated, particularly when pacemaker system infection is present. The success rate of such extraction attempts for ventricular endocardial leads over the past 5 years was reviewed. Extraction was usually successful (six of seven attempts) in patients with silicone rubber nontined (or short-tined) older ventricular endocardial leads (Group A). However, in patients with newer urethane long-tined ventricular endocardial leads (Group B), extraction was unsuccessful in three of four attempts. Because of entrapment of the distal electrode tip in the right ventricular apex, manual traction of these leads resulted in permanent conductor material stretching with resultant urethane insulator material breakage in the region of the joints with proximal and distal electrodes. The one successful extraction in Group B was technically difficult and appeared to create a significant risk of intracardiac lead separation. This experience indicates that with improved pacemaker lead design decreased lead dislodgment has been obtained at the cost of increased difficulty of ventricular endocardial lead extraction. Such difficulty should be anticipated when a clinical decision is made to attempt to extract the new urethane long-tined ventricular leads.

Adult↗
PubMed1983

Ventricular septal rupture after acute myocardial infarction: diagnosis by two-dimensional echocardiography.

A 69-year-old woman had ventricular septal rupture after acute anterolateral myocardial infarction. The defect was demonstrated directly by two-dimensional echocardiography. The appearance of negative contrast in the right ventricle during systole and microbubbles traversing the defect from right to left during diastole further confirmed the rupture. Two-dimensional echocardiography also accurately characterized the nature and extent of associated myocardial damage.

Aged↗
PubMed1983

Atrioventricular sequential pacing: comparison with ventricular pacing using systolic time intervals.

Nine patients with programmable atrioventricular sequential pacers were studied using systolic time intervals (QS2--the total electrical and mechanical systole, left ventricular ejection time, and pre-ejection period). These measurements were obtained by simultaneous recording of the electrocardiogram, phonocardiogram, and carotid pulse tracing. There was a dramatic fall of left ventricular ejection time (LVET) and an increase of the pre-ejection time (PEP) in all patients when the pacers were programmed from the atrioventricular to the ventricular mode at constant heart rate. This resulted in an increase of the ratio PEP/LVET from .428 to .574 suggesting loss of ventricular function. These measurements all reversed to baseline values when the pacers were re-programmed back to the atrioventricular mode. This study suggests systolic time intervals might be useful to select non-invasively pacer parameters such as mode, rate, and effective PR interval in order to provide the best hemodynamics in a given patient.

Aged↗
PubMed1983

Stability of permanent transvenous dual-chamber pacing electrodes during cardiopulmonary resuscitation.

For long-term dual-chamber permanent pacing, atrial and ventricular lead stability is essential. In our overall experience with such pacing systems, four patients suffered cardiac arrest at a time distant from their pacemaker implantation. Since all four patients received prolonged closed chest cardiopulmonary resuscitation, we analyzed these events to determine whether dual-chamber endocardial electrodes would remain stable in such traumatic conditions. Reliable atrial and ventricular lead position was confirmed at autopsy in the three patients whose resuscitation attempts were unsuccessful and, in the fourth patient, by continued normal lead position and pacing function post-resuscitation. The keys to this stability include the use of tined atrial and ventricular endocardial leads and specific maneuvers at the time of implantation to verify fixation. Long-term stability of presently available endocardial leads in dual-chamber pacing systems can thus be anticipated.

Aged↗
PubMed1983

Total venous obstruction following atrioventricular sequential pacemaker implantation.

We describe a case of a 79-year-old woman who developed pain and pitting edema of the upper right extremity due to total venous obstruction following the implantation of an atrioventricular sequential pacemaker. She was treated by arm elevation and anticoagulation after which the pain and edema subsided. To our knowledge, this is the first reported case of this complication occurring following implantation of a dual-chamber pacing system. We recommend that venographic studies be done after implantation if apparent arm swelling occurs, and that anticoagulant therapy be instituted if thrombosis is present.

Aged↗
PubMed1983

Cardiovascular manifestations of mixed connective tissue disease in adults.

To assess the nature and distribution of cardiovascular abnormalities associated with mixed connective tissue disease, we studied 38 patients with overlapping clinical manifestations of systemic lupus erythematosus, progressive systemic sclerosis and polymyositis, and circulating antibodies to nuclear ribonucleoprotein. The protocol included taking a medical history and a physical echocardiogram, and pulmonary function tests. Cardiac catheterization was performed on 17 patients. Postmortem examination was performed on four of the five patients who died during follow-up. Acute pericarditis and/or pericardial effusion was detected in 11 patients (29%) and mitral valve prolapse was identified in 10 patients (26%). Marked intimal hyperplasia of coronary arteries was observed in all four hearts that were autopsied and perivascular and myocardial leukocytic aggregates were present in two hearts. Pulmonary vascular resistance was elevated in 11 of the 17 patients who underwent cardiac catheterization. In summary, cardiovascular abnormalities associated with mixed connective tissue disease include acute pericarditis and/or effusion, mitral valve prolapse, intimal hyperplasia of coronary arteries, perivascular and myocardial leukocytic infiltrates, and pulmonary hypertension.

Adolescent↗
PubMed1981

Clinical experience with permanent atrioventricular sequential pacing.

In a 23-moth period, we implanted 26 permanent atrioventricular (AV) sequential pacing units in 11 women and 15 men ranging from 37 to 85 years old (mean, 68 years). Indications for pacing were complete heart block n 12 patients and sick sinus syndrome in 14 patients. Cardiac index, using standard thermodilution techniques, was determined in 9 patients during ventricular pacing and AV sequential pacing at constant heart rate. Atrioventricular sequential pacing was superior in all patients, with a mean increase in cardiac index of 22% (p greater than 0.01). Complications of AV sequential pacing included the need to revise two pulse generator pockets due to the large size of the pulse generator. One transvenous atrial lead displacement occurred in a patient who had previously undergone right atrial appendage ligation at open-heart operation. No failures of pacing or sensing occurred during 279 patient-paced months. The theoretical hemodynamic advantage of AV sequential pacing has been confirmed in this clinical trial. Experience with electrode placement and improvements in pulse generator design should aid in eliminating complications with this pacing modality.

Adult↗