Hans de Swart

Left ventricular septal and apex pacing for optimal pump function in canine hearts

OBJECTIVES The goal of this study was to test the hypothesis that left ventricular (LV) pump function is optimal when pacing is performed at the LV near the sites where the impulses exit the Purkinje system. BACKGROUND Pacing at the conventional site, the right ventricular (RV) apex, adversely affects hemodynamics. During normal sinus rhythm (SR), electrical activation of the working myocardium starts at the LV septal endocardium and spreads from apex to base. METHODS Experiments were conducted in anesthetized open-chest dogs with normal ventricular conduction to investigate hemodynamic effects of pacing at various epicardial LV sites, the RV apex, and combinations of these sites (n = 11) and of RV and LV septal pacing (n = 8). The LV septal endocardium was reached via the RV by puncturing through the septum with a barbed electrode. Left ventricular systolic (LVdP/dtpos and stroke work) and diastolic (LVdP/dtneg and Tau) function were assessed using pressure-volume relations (conductance catheter technique). RESULTS Left ventricular systolic and diastolic function were highly dependent on the site of pacing, but not on QRS duration. Left ventricular function was maintained at SR level during LV septal, LV apex, and multisite pacing, was moderately depressed during pacing at epicardial LV free wall sites, and was most severely depressed during RV apex pacing. On average, RV septal pacing did not improve LV function, compared with RV apex pacing, but in each experiment one (variable) RV pacing site was found, which only moderately reduced LV function. CONCLUSIONS During ventricular pacing, LV pump function is maintained best (i.e., at SR level) when pacing at the LV septum or LV apex, potentially because pacing from these sites creates a physiological propagation of electrical conduction.

Effects of thrombolytic therapy in unstable angina: Clinical and angiographic results

The incidence of intracoronary thrombus and the effects of thrombolytic therapy were studied in 41 patients with unstable angina. All patients underwent coronary angiography 2 to 69 h (mean 19) after their last attack of chest pain. Immediately after angiography, 21 patients received intracoronary streptokinase (250,000 IU in 45 min) and were retrospectively analyzed. Twenty patients received intravenous recombinant tissue-type plasminogen activator (rt-PA) (100 mg in 3 h) and were involved in a prospective study. Eleven of the 21 patients from the streptokinase group and 11 of the 20 patients from the rt-PA group showed a decrease in the severity of the coronary stenosis on repeat angiography 1 day later. A decrease in coronary obstruction was primarily observed in 10 of 13 patients with a complete stenosis and in 6 of 9 patients with a subtotal stenosis and markedly diminished coronary flow. Improvement in coronary anatomy was not determined by the clinical characteristics of the patients. Twenty-eight of the 41 patients had angiographic evidence of intracoronary thrombus formation before and 16 had such evidence after thrombolytic treatment. Nine patients developed a small increase in serum cardiac enzymes before or during treatment. Ischemic symptoms and the incidence of surgical or angioplastic intervention were not different in patients with or without a reduction in coronary artery stenosis after fibrinolytic therapy. These observations suggest a high incidence of coronary thrombosis in patients with unstable angina. The data do not permit assessment of the clinical therapeutic efficacy of thrombolytic therapy. Better risk stratification and placebo-controlled prospective studies are required to obtain information on the risk/benefit ratio of such therapy in unstable angina.

Psychosocial characteristics and recurrent events after percutaneous transluminal coronary angioplasty

This study examines the effect of anger and vital exhaustion on recurrent events after percutaneous transluminal coronary angioplasty (PTCA). Data came from 149 patients (123 men and 26 women) who underwent successful PTCA. During 18 months of follow-up, there were 37 recurrent events (25%) for which there was objective evidence of new or progression of coronary disease. The 123 male patients with high anger were significantly more likely to have multivessel disease before PTCA (odds ratio 2.42; p = 0.04), after controlling for standard heart disease risk factors. High-anger male patients also had a threefold increased risk for recurrent events after PTCA (RR 2.94; p = 0.01), which remained marginally significant after accounting for other heart disease risk factors and residual stenosis after PTCA (RR 2.33; p = 0.09). Among female patients, these relations were much weaker and not statistically significant. Among male patients, additional adjustment for vital exhaustion did not change the risk for recurrent events associated with high anger. A composite index of psychosocial risk based on anger and vital exhaustion was significantly related (p = 0.02) to events after PTCA after adjustment for standard heart disease risk factors. These findings add to the growing body of research on the role of psychosocial factors on clinical course in patients with coronary artery disease.

Culprit lesion morphology and stenosis severity in the prediction of reocclusion after coronary thrombolysis: Angiographic results of the APRICOT study

OBJECTIVES In the APRICOT study (Antithrombotics in the Prevention of Reocclusion In Coronary Thrombolysis), we sought to determine whether angiographic characteristics of the culprit lesion could predict reocclusion after successful thrombolysis and to analyze the influence of three antithrombotic treatment regimens. BACKGROUND After successful thrombolysis, reocclusion is a major problem. Prediction of reocclusion by angiographic data and choice of antithrombotic treatment would be important for clinical management. METHODS After thrombolysis, patients were treated with intravenous heparin until initial angiography was performed within 48 h. Patients with a patent infarct-related artery were eligible. Three hundred patients were randomly selected for treatment with coumadin, aspirin (300 mg once daily) or placebo. Patency on a second angiographic study after 3 months was the primary end point of the study. RESULTS Reocclusion rate was 25% with aspirin, 30% with coumadin and 32% with placebo (p = NS). Lesions with > 90% stenosis reoccluded more frequently (42%) than did those with < 90% stenosis (23%) (p < 0.01). Reocclusion rate of smooth lesions was higher (34%) than that of complex lesions (23%) (p < 0.05). In lesions with < 90% stenosis, the reocclusion rate was lower with aspirin (17%) than with coumadin (25%) or placebo (30%) (p < 0.01). In complex lesions, the reocclusion rate was lower with aspirin (14%) than with coumadin (32%) or placebo (25%) (p < 0.02). Multivariate analysis showed only stenosis severity > 90% to be an independent predictor of reocclusion (odds ratio 2.31, 95% confidence interval 1.28 to 4.18, p = 0.006). CONCLUSIONS Angiographic features of the culprit lesion after successful coronary thrombolysis significantly predict the risk of reocclusion: high grade (> 90%) stenoses reoccluded more frequently. Aspirin was effective only in complex and less severe lesions (< 90% stenosis). These findings should prompt investigation of the effects of an aggressive approach to patients with severe residual stenosis.

Value of exercise Doppler-echocardiography in patients with mitral stenosis

The value of exercise Doppler-echocardiography was studied in 60 patients with mitral valve stenosis. Patients were divided in three groups. In patients with a mitral valve area of more than 1.4 cm2, maximal and mean diastolic gradient over the mitral valve increased from 13.2 +/- 3.6 to 18.4 +/- 5.4 and from 5.2 +/- 1.9 to 8.8 +/- 3.0 mmHg, respectively. In patients with a mitral valve area in between 1.0 and 1.4 cm2, maximal and mean gradient increased from 19.0 +/- 8.0 to 28.1 +/- 8.9 and from 8.8 +/- 4.9 to 14.8 +/- 6.4 mmHg, respectively. In patients with a mitral valve area of less than 1 cm2, the maximal gradient increased from 21.5 +/- 5.8 to 34.2 +/- 8.7 and mean gradient increased from 11.8 +/- 4.1 to 20.3 +/- 5.8 mmHg. Mean tricuspid regurgitation velocity increased from 2.9 +/- 0.5 m/s to 3.6 +/- 0.5 m/s, indicating increase in right ventricular to right atrial pressure difference from 34 mmHg to 52 mmHg. We conclude that exercise during the Doppler-echocardiographic evaluation provides additional information about the hemodynamic significance of mitral stenosis and can therefore be of value in decision making.

A new hemostatic puncture closure device for the immediate sealing of arterial puncture sites

After angiography, 6 to 24 hours of bedrest is indicated to assure that adequate hemostasis of the femoral artery has been achieved. Recently, a new hemostatic puncture closure device (HPCD) has been developed, which consists of a resorbable polymer anchor, a resorbable suture, a small collagen plug and an 8Fr delivery device. The device is delivered into the femoral artery through the introducer sheath, the anchor is secured against the intraluminal artery wall, and the collagen plug is deployed on the arterial wall. The prototype of the HPCD was used in 20 patients administered heparin. After insertion of the HPCD, hemostasis was achieved in 1.2 +/- 2.1 minutes; in 2 patients a light pressure dressing was applied for 4 hours to stop oozing. No late bleeding occurred. In 1 patient the positioning suture broke, requiring the application of a pressure bandage. Patients were uneventfully mobilized after 6.7 +/- 3.5 hours. In all patients serial duplex scanning of the femoral artery was performed before and after 1, 7, 30 and 90 days after HPCD placement. In 5 patients a small subcutaneous hematoma close to the site of introduction could be detected by ultrasound 1 day after catheterization. All but 1 patient had normalization of the flow patterns in the femoral artery. It is concluded that: (1) the HPCD is an effective device to achieve immediate hemostasis after arterial catheterization despite antithrombotic therapy, (2) early mobilization was uneventful, (3) duplex ultrasound studies demonstrated only transient changes in the punctured femoral artery, and (4) further investigations are needed to establish the efficacy and safety of the device.

Myocardial rupture after myocardial infarction is related to the perfusion status of the infarct-related coronary artery.

Acute or subacute myocardial rupture is a serious and often lethal complication of acute myocardial infarction. The role of an occluded or open culprit coronary artery on the occurrence of this complication is not clear. We therefore reviewed the perfusion status of the infarct-related coronary artery retrospectively in 57 patients who had an initially nonfatal rupture (group A) and 28 patients (including 9 patients from group A) with a postmortem diagnosis of myocardial rupture (group B). In 35 of the 57 patients in group A, a coronary angiogram was available. Complete occlusion or ineffective reperfusion was present in 30 (89%) of 35 patients. The remaining 22 patients of group A showed no clinical signs of reperfusion. All 28 patients of group B had inadequate reperfusion of the infarcted area on postmortem angiography and macroscopic examination of the coronary artery. Our observations suggest that myocardial rupture typically occurs in an infarcted area without reperfusion.

Termination of tachycardias by interrupting blood flow to the arrhythmogenic area

The hypothesis that production of ischemia or cooling of an arrhythmogenic area or pathway could interrupt tachycardias was tested by subselective catheterization of the coronary artery supplying the site of origin of ventricular tachycardia (9 patients), the accessory pathway (2 patients) and the site of origin of atrial tachycardia (1 patient). Ventricular tachycardia was reproducibly terminated and reinduction temporarily prevented in 8 of the 9 patients by occlusion of the artery or administration of iced isotonic saline. Block in the accessory pathway was obtained in 1 of the 2 patients with Wolff-Parkinson-White syndrome. Selective cooling through the atrioventricular nodal artery in 1 patient terminated his circus movement tachycardia. Reproducible termination of a continuous atrial tachycardia was obtained by cooling of the atrial branch supplying the site of origin of the arrhythmia. These data demonstrate the feasibility of identification and selective catheterization of the coronary artery branch supplying blood to an arrhythmogenic area or pathway and suggest a new possibility for treatment of tachycardias by permanently blocking the blood supply to the site of origin or pathway of a tachycardia.

Early referral for intentional rescue PTCA after initiation of thrombolytic therapy in patients admitted to a community hospital because of a large acute myocardial infarction

BACKGROUND If no in-house facilities for percutaneous transluminal coronary angioplasty (PTCA) are present, thrombolytic therapy is the treatment of choice for acute myocardial infarction (AMI). A few studies have shown benefit from rescue PTCA in patients directly admitted to centers with PTCA facilities. The obvious question arises whether patients with AMI initially admitted to a community hospital can benefit from early transfer for intentional rescue PTCA. METHODS AND RESULTS One hundred sixty-five patients were transferred early for intentional rescue PTCA from a community hospital at a distance of 20 miles. On arrival at the angioplasty center, bedside markers were used to determine reperfusion. In case of obvious reperfusion, no invasive procedure was done; otherwise, coronary angiography and rescue PTCA, if necessary, was performed. During transfer, 1 (1%) patient died and 15 (9%) patients had arrhythmic or hemodynamic problems. Median time delay between onset of chest pain and arrival at the community hospital and the PTCA center was 61 minutes (range 0 to 413) and 150 minutes (range 28 to 472), respectively. In 66 (40%) patients, reperfusion was diagnosed by noninvasive reperfusion criteria on arrival at the PTCA center (group 1). Ninety-eight (59%) patients without evident noninvasive criteria of reperfusion underwent angiography 187 median minutes after the onset of chest pain. Forty-one (25%) patients had Thrombolysis In Myocardial Infarction grade 3 flow, and no further intervention was performed (group 2). In the remaining 57 (35%) patients, rescue PTCA was performed, which was successful in 96% (group 3). In-hospital mortality rate was lowest in group 1 compared with the other 2 groups (0% vs 7% vs 11%; P <.05). Reinfarction was highest in group 1 compared with the other groups (17% vs 5% vs 2%; P <.01). No significant differences were found in coronary artery bypass grafting, stroke, or bleeding complications. The 1-year follow-up data showed low revascularization rates; 2 (1%) patients died after discharge from the hospital. CONCLUSIONS Early transfer of patients with large AMI for intentional rescue PTCA can be done with acceptable safety and is feasible within therapeutically acceptable time limits and results in additional early reperfusion in 33% of patients. A large, randomized, multicenter trial is needed to compare efficacy of intravenous thrombolytic treatment in a community hospital versus early referral for either rescue or primary PTCA.

Usefulness of the rescue pt catheter to remove fresh thrombus from coronary arteries and bypass grafts in acute myocardial infarction

I the setting of an acute myocardial infarction (AMI), thrombolytic therapy has proved to reduce mortality and improve left ventricular function.1–3 A good or even better alternative is primary angioplasty.4–6 Several devices have been developed to remove thrombus material. The disadvantages of most of these devices are that they are complicated, and difficult to handle in the acute setting for interventionalists who are not experienced with these devices. We describe the clinical experience with a simple thrombectomy system using a catheter that can be handled like a balloon. This study evaluates the safety and efficacy of the Rescue percutaneous thrombectomy (PT) system (Boston Scientific, Maple Grove, Minnesota) in the setting of AMI or unstable angina pectoris. • • • The thrombectomy system consists of a very flexible, 4.5Fr polyethylene catheter that can be advanced over a standard 0.014-in guidewire through a 7Fr guiding catheter using a monorail system. The catheter has an oblique tip to facilitate passage through the lesion and a marker to improve visibility during fluoroscopy (Figure 1). The proximal end has an extension tube connected to a vacuum pump (0.8 bar) with a collection bottle. The removed thrombus material is collected on a filter in the collection bottle. While the catheter is advanced and pulled back through the thrombus, continuous suction is applied. When necessary, several runs can be performed. In case of distal embolization, the catheter can be advanced distally over the guidewire to remove the embolized material. Thrombectomy using the Rescue PT system was considered when a coronary angiogram recorded in the setting of an AMI raised the suspicion of a considerable amount of thrombus in a venous coronary artery bypass graft or native coronary artery. At the beginning of the procedure 10,000 IU of heparin was administered to the patients not pretreated with a thrombolytic agent. A coronary angiogram was performed before and after guidewire placement, after every passage of the Rescue PT catheter, and when applicable after additional coronary intervention. Coronary flow was classified according to the Thrombolysis In Myocardial Infarction (TIMI) trial.7 Angiographic analysis was performed to evaluate presence and removal of the thrombus and distal embolization. The removal of thrombus was also determined by the material on the filter in the collection bottle. The use of additional medication and coronary intervention, including stent placement, were at the discretion of the operator. Fifty-one lesions were treated in 50 patients (8 women and 42 men). One patient had a thrombus in the left anterior descending (LAD) artery and first diagonal branch because of distal embolization of thrombus from the proximal LAD artery after treatment with a thrombolytic agent. In 30 patients (60%) thrombectomy was performed after failed thrombolysis. In 43 patients (86%) the estimated age of the thrombus was ,6 hours, in 7 patients, thrombus age was 6 to 10 hours, and in 2 patients, it was .10 hours. In 45 patients thrombectomy was performed in a native coronary artery and in the remaining 5 patients in a venous coronary artery bypass graft (graft age range 13 to 18 years). The lesion could be reached in all vessels and thrombus material was removed from 48 of the 51 From the Department of Cardiology, University Hospital Maastricht, Maastricht; and Department of Cardiology, Catharina Ziekenhuis, Eindhoven, The Netherlands. Dr. van Ommen’s address is: Department of Cardiology, University Hospital Maastricht, PO Box 5800, 6202 Maastricht, The Netherlands. E-mail: vvo@scar.azm.nl. Manuscript received October 20, 2000; revised manuscript received and accepted February 27, 2001. FIGURE 1. Photograph of the tip of the Rescue PT system showing the oblique tip and the marker band.