Reversibility of tachycardia-induced cardiomyopathy after cure of incessant supraventricular tachycardia.

Seven of 17 patients with incessant supraventricular tachycardia caused by an accessory pathway with a long retrograde conduction time were seen with symptoms or echocardiographic signs of a tachycardia-induced cardiomyopathy. Three patients were in New York Heart Association functional class II with dyspnea and four were in class III. Eight patients (six with tachycardia-induced cardiomyopathy) underwent surgery because of failure of medical treatment (including one patient in functional class I) and one underwent direct current catheter ablation of the atrioventricular (AV) node. In six patients echocardiograms recorded before and after the procedure were available. Before surgery or direct current ablation the mean left ventricular ejection fraction was 36.3 +/- 8.7%, the left ventricular end-diastolic diameter 55.7 +/- 7.6 mm and the left ventricular end-systolic diameter 44.3 +/- 7.8 mm. A mean of 21.6 +/- 6.8 months after the procedure the mean left ventricular ejection fraction increased to 58.6 +/- 8.0%, the left ventricular end-diastolic diameter decreased to 49.0 +/- 3.6 mm and the left ventricular end-systolic diameter decreased to 32.2 +/- 2.7 mm; all six patients were in functional class I. These results confirm that control of incessant tachycardia leads to a regression of symptoms and signs of cardiomyopathy and progressive normalization of the dimensions of the heart. Because of these findings, surgery should be considered early in patients with an accessory AV pathway and incessant tachycardia. The presence of a tachycardia-induced cardiomyopathy should therefore be an indication for surgery rather than a contraindication.

Long-term follow-up (12 to 35 weeks) after dynamic cardiomyoplasty.

OBJECTIVES: To obtain information on the long-term effects of dynamic cardiomyoplasty on hemodynamics and muscle histology, this surgical method was evaluated in goats. BACKGROUND: Dynamic cardiomyoplasty has been introduced as a new method to treat patients with severe cardiac failure. METHODS: In 24 goats, the left latissimus dorsi muscle was wrapped around the heart. The muscle was then subjected to progressive electrical stimulation. In 16 goats, invasive transesophageal Doppler echocardiographic measurements and histologic evaluation of the latissimus dorsi muscle were performed at > or = 12 weeks after the wrapping. RESULTS: Only two goats showed an increase in aortic and left and right ventricular pressures concomitant with increased aortic flow during latissimus dorsi muscle stimulation both before and after induction of cardiac failure using imipramine. This was accompanied by a preserved latissimus dorsi muscle structure and nearly complete transformation to type I muscle fibers. The remaining 14 goats showed extensive lipomatosis in the latissimus dorsi muscle, with severe intimal hyperplasia and proliferation of smooth muscle cells in the walls of the thoracodorsal artery and its branches. An increase in endoneural and endomysial connective tissue was observed, with some goats showing destroyed nerve branches near the electrodes. These findings differed from those observed after long-term electrical stimulation of goat latissimus dorsi muscle in situ. CONCLUSIONS: Dynamic cardiomyoplasty is of use in the treatment of severe heart failure if the histologic structure of the wrapped latissimus dorsi muscle remains intact. Long-term results in goats suggest that the current approach used in dynamic cardiomyoplasty may lead to deterioration of the wrapped muscle.

Imipramine induced heart failure in the dog: a model to study the effect of cardiac assist devices.

OBJECTIVE: The value of intravenous imipramine in creating a reversible model of short term heart failure was evaluated in anaesthetised dogs. METHODS: Acute effects of imipramine were studied in 11 dogs using invasive haemodynamic pressure measurements and two dimensional echo evaluation. RESULTS: After a 30 min imipramine infusion (7.5 mg.kg-1.h-1), positive left ventricular dP/dtmax decreased from 1368(SEM 108) to 909(119) mm Hg.s-1 (p < 0.05), left ventricular end diastolic pressure increased from 8(1) to 12(2) mm Hg (p < 0.05), while left ventricular pressure decreased from 106(4) to 87(6) mm Hg (p < 0.05). Cessation of imipramine administration resulted within 60 min in partial restoration of cardiac function. This deterioration and subsequent recovery was also demonstrated with echocardiographic measurements, which showed a decrease in ejection fraction from 54(3)% to 28(2)% (p < 0.05). During administration of imipramine neither significant electrophysiological changes nor supraventricular/ventricular arrhythmias were seen. Repeated infusions of imipramine in three anaesthetised dogs with a two week interval showed the reproducibility of the haemodynamic effects and the recovery of ventricular function. Since the model was developed to evaluate the use of cardiomyoplasty in heart failure, the effect of imipramine was also evaluated on latissimus dorsi muscle contraction. Administration of imipramine did not affect skeletal muscle force development at the dosage used to create heart failure. CONCLUSIONS: This model can be used to produce short term reversible heart failure in anaesthetised animals to test the efficacy of supportive interventions like dynamic cardiomyoplasty, intra-aortic balloon pumping, and mechanical cardiac assist devices.

Histopathology of rejection in DLA-identical canine orthotopic cardiac allografts.

The process of chronic rejection is the limiting factor in long term survival after cardiac transplantation. As part of a study of this process in experimental orthotopic heart transplantation, morphological changes during the course of rejection are described in DLA-identical beagle littermates, obtained by serial percutaneous cardiac biopsy. A total of 153 biopsies were performed on 19 dogs. Mean survival time was 88.11 days (14--494 days) without the use of immunosuppressive therapy. Eight dogs, surviving only 4 weeks, showed a histological pattern that resembled delayed acute rejection, with extensive lymphocellular infiltrate, vascular damage, and myocytolysis. In the 11 dogs which survived more than 4 weeks there was a slight and sometimes transient lymphocellular infiltrate. But progressive vascular lesions could be seen from the 2nd week consisting mainly of medical proliferation involving intramural vessels as well as epicardial vessels. Capillary changes were prominant and the rate of capillary damage seems to be an indication of graft survival prognosis.

Orthotopic canine heart transplantation: left ventricular contractility during chronic rejection.

Myocardial left ventricular contractility is assessed in 8 orthotopic heart-transplanted dogs during chronic rejection by a noninvasive method. The mean circumferential velocity of shortening (Vcf) is calculated from endocardial marker motion on cinefilms. A model for chronic rejection after cardiac transplantation was obtained by histocompatibility matching in DLA identical Beagle littermates. No immunosuppressive treatment was used. All dogs eventually died of chronic rejection; mean survival time was 112.5 days. LV contractility shows the following pattern: Chronic rejection causes an important contractility decrease (P less than 0.001) with two significant drops: (1) from the week preoperative to the first week after transplantation (P less than 0.02) and (2) from week terminal minus one to the terminal week (P less than 0.01). This study describes the technique and the changes in Vcf observed over a period of time in a predictable model.

Influence of Duraflo II heparin-treated extracorporeal circuits on the systemic inflammatory response in patients having coronary bypass.

Cardiopulmonary bypass generates a systemic inflammatory response, including the activation of leukocytes, contributing to postoperative morbidity. To evaluate whether the use of heparin-treated extracorporeal circuits could reduce the inflammatory reaction in patients undergoing cardiopulmonary bypass, we conducted a prospective clinical study on 14 patients having coronary artery bypass in whom perfusion was done randomly with either Duraflo II heparin-treated circuits or with nontreated circuits. In both groups systemic heparinization was performed before cardiopulmonary bypass. The use of heparin-treated circuits resulted in a reduction of systemic inflammatory activation during cardiopulmonary bypass. This was reflected by lower plasma levels of soluble tumor necrosis factor receptors (p < 0.05) and of interleukin-6 and interleukin-8 (p < 0.05), manifest after release of the aortic crossclamp. Furthermore, 6 and 12 hours after aortic crossclamp release significantly lower levels of the soluble E-selectin (p < 0.05) were observed in the Duraflo II group. In patients in whom noncoated circuits were used, a significant decrease in circulating soluble intercellular adhesion molecule 1 (p < 0.05) was found early during bypass. All these observations suggest that the use of a heparin-treated extracorporeal circuit reduces the systemic inflammatory activation and may after the leukocyte-endothelium interaction.

Automated infusion of nitroglycerin to control arterial hypertension during cardiac surgery.

OBJECTIVE: To evaluate the feasibility of closed-loop blood pressure control during cardiac surgery. DESIGN: A closed-loop system regulated peroperative hypertension by controlling the infusion rate of the vasodilator nitroglycerin (NTG). The controller consisted of a regulator which was monitored by a supervisory computer program. Mean arterial pressure (MAP) was calculated every 5 s from measurements of the radial artery pressure signal. The regulator calculated an NTG infusion rate with each new MAP measurement. The supervisory computer program monitored the regulator's actions and adapted or overruled the regulator when required. SETTING: The cardiac surgery operating room. PATIENTS: 46 patients who were scheduled for cardiac surgery and who developed peroperative hypertension. INTERVENTIONS: Patients were scheduled for either bypass or valve replacement surgery. The closed-loop system was used to control hypertension before and after cardiopulmonary bypass. The use of the closed-loop system did not require deviation from the protocol normally used during cardiac surgery. All patients received standard continuous anaesthesia with opioids. MEASUREMENTS AND RESULTS: Initial automatic control was achieved in 9.4 (4.1 SD) min. The percentage of time that MAP remained in a range around the target MAP of +/- 10 and +/- 20 mmHg was 74 and 94%, respectively. The mean NTG infusion rate while MAP was within 5 mmHg of target MAP was 1.14 (0.84 SD) micrograms kg-1 min-1. Target MAP was set between 65 and 90 mmHg. There was a small group of patients (6 out of 46) who did not respond to NTG and required alternative drug therapy. CONCLUSIONS: The controller provided fast and stable control in all patients. The expert knowledge implemented through the supervisory computer program enabled the controller to respond adequately to the rapid changes in arterial pressures commonly associated with cardiac surgery. We conclude that closed-loop control of arterial pressure is feasible not only in the cardiac surgical care unit but also during cardiac surgery.

Changes in canine latissimus dorsi muscle during 24 wk of continuous electrical stimulation.

To study functional, structural, and biochemical adaptations to electrical stimulation of striated muscle in a large animal, the canine latissimus dorsi (LD) muscle was conditioned continuously for 24 wk with an increasing number of pulse bursts (burst duration 250 ms, burst frequency 30 Hz). Force measurements in vivo after 12 wk showed a significant decrease in the ripple, the ratio of interstimulus to peak force amplitude, from 0.94 +/- 0.03 to 0.13 +/- 0.08 (SE; n = 8, P less than 0.05), indicating reduction in contractile speed. Also the steep part of the force-frequency relation shifted to lower frequencies. A significant change in fiber-type composition was seen with both enzyme- and immunohistochemistry, manifested by an increase of type I fibers from 29.5 +/- 2.9 to 83 +/- 8% (SE; n = 8, P less than 0.05). During this period a transient rise in the number of type IIc/Ic fibers (from 3 to 10%) was seen. In the stimulated muscle, capillary-to-fiber ratio increased from 1.9 +/- 0.4 to 2.7 +/- 0.1 (P less than 0.05). A significant increase in mitochondrial volume was also seen, especially in the peripheral part of the fiber. Both creatine kinase and lactate dehydrogenase revealed a significant decline in activity within 12 wk. At the same time a shift in lactate dehydrogenase-isozyme pattern was observed toward the cardiac composition. No additional changes occurred after 12 wk of stimulation, indicating that conversion of the canine LD muscle was complete within this period.

Acquired ventricular septal defect and mitral insufficiency without pericardial effusion after stab wound to the chest.

Echocardiography has a role in the management of acute complications of penetrating cardiac trauma. We report the case of a 30-year-old man who sustained a stab wound to the chest. In this case a traumatic perforation of the ventricular septum and the anterior leaflet of the mitral valve caused by a knife occurred without pericardial effusion. The diagnosis was made by transthoracic echocardiography. The ability of transesophageal echocardiography to delineate the intracardiac injuries more precisely helped to guide the surgical procedure.

Postoperative pulmonary function abnormalities after coronary artery bypass surgery.

In 18 patients, postoperative effects of coronary bypass surgery were evaluated. Pulmonary function studies were conducted preoperatively, and 1 and 6 weeks postoperatively, by means of spirometry, respiratory pressures, body plethysmography and impedance measurement of the respiratory system using the forced oscillation technique. One week postoperatively, total lung capacity (P less than 0.0001), inspiratory vital capacity (P less than 0.0001) forced expiratory volume (P less than 0.0001) and functional residual capacity (P less than 0.01) decreased significantly, while residual volume remained unchanged. This restrictive respiratory impairment was accompanied by significant decreases in inspiratory (P less than 0.0001) and expiratory (P less than 0.01) mouth pressures and significant decreases in respiratory resistance values (P less than 0.01). Six weeks postoperatively, significant differences in total lung capacity (P less than 0.0001), inspiratory vital capacity (P less than 0.0001) and forced expiratory volume (P less than 0.0001) persisted, while respiratory pressures returned to the preoperative values. It is concluded that respiratory muscle weakness contributes to the immediate postoperative restrictive lung function loss. Furthermore, structural alterations of chest wall mechanics have to be supposed for the persisting late restrictive pulmonary impairment.

Diagnosis and treatment of patients with accessory pathways.

Of the accessory pathways, partially or totally bypassing the atrio-ventricular conduction system, the bundle of Kent is the most common type. The electrocardiographic (ECG) expression of preexcitation depends upon the contribution of the activation fronts over the AV node and the accessory pathway. From the polarity of the delta wave in the surface ECG and from the behavior during electrophysiologic study, the location of the accessory pathway can be derived. The presence of an accessory pathway may induce circus movement tachycardia and, in case of atrial fibrillation, high ventricular rates possibly leading to sudden death. Noninvasive techniques are able to identify the patient at high risk. Treatment modalities are pharmacologic or surgical, whereas ablation techniques are still under investigation.

Color Doppler imaging of the right gastroepiploic artery as an in situ coronary artery bypass graft.

In recent years the right gastroepiploic artery (GEA) has been used as an in situ graft in coronary artery bypass grafting (CABG). The specific anatomical course of the GEA graft enables the use of color Doppler imaging technique to evaluate its patency. The results in 21 patients demonstrate the efficiency of this technique; postoperative angiography to establish patency can therefore be avoided.

Use of a removable vena caval filter for prevention of recurrent embolism after emergency pulmonary embolectomy: a flexible approach.

Intraluminal vena caval filters, inserted via the transvenous approach, are used often in the prevention of recurrent pulmonary embolism. Until lately, such filters have been unremovable. In a recent case, however, we treated a patient who experienced acute massive pulmonary embolism after having undergone an emergency right hemicolectomy. He underwent a successful emergency pulmonary embolectomy with the help of cardio-pulmonary bypass; to prevent recurrent embolism, we inserted a removable intracaval filter through the right atriotomy with an introducer set. On the 7th postoperative day, the absence of significant residual thrombi was confirmed by means of phlebography, and the caval filter was removed percutaneously via the femoral approach. Although the value of routine use of the filter in this application has yet to be established, we feel that it warrants further investigation because it relieves the surgeon, during an emergency procedure, of the need to decide quickly whether or not to place a filter. The question becomes one of whether or not to remove the filter, and that decision can await the results of proper postoperative diagnostic studies.

[Cardiomyoplasty: a new alternative in chronic heart failure]. / Het wikkelhart: een nieuw alternatief bij chronisch hartfalen.

The technique of cardiomyoplasty to support the failing heart as applied in the first two patients in The Netherlands is reported. Indications are presented for the selection of patients who might benefit from a cardiomyoplasty procedure, considering its experimental nature.

[Double supraventricular tachycardia and its surgical treatment]. / Kettös supraventricularis tachycardia és sebészi kezelése.

A case history is presented of a patient in whom a left-free-wall accessory pathway was surgically ablated to treat symptomatic Wolff--Parkinson--White syndrome. Subsequently, AV-nodal reentrant tachycardia became manifest. The patients's AV-nodal reentrant tachycardia was interrupted by Cox's discrete cryosurgical procedure. As a result of analysis of these cases of dual substrates for reentrant supraventricular tachycardia, ECG and electrophysiological means for differential diagnosis has been developed. These are discussed herein.