Biomedical subjects

O C Penn

Publications and source records attributed to O C Penn.

At least 19 recordsLinked to original sources

PubMed1998

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.

Adult↗

PubMed1998

Structural alterations in the latissimus dorsi muscles in three patients more than 2 years after a cardiomyoplasty procedure.

AIMS: The long-term effects of the use of the latissimus dorsi muscle for dynamic cardiomyoplasty were studied. Skeletal muscle fast fatiguable type II fibres are transformed to highly fatigue-resistant type I fibres in animal models, and is assumed to occur in men. However, it is not known whether this same transformation occurs in patients with chronic heart failure. METHODS AND RESULTS: Three patients who underwent a cardiomyoplasty procedure (pre-operative NYHA class IV) were studied. The left latissimus dorsi muscle was stimulated, according to routine clinical protocol, with 30 Hz bursts in a 2:1 ratio to cardiac activation. The patients died more than 2 years after surgery and five autopsy samples were obtained at defined places in the wrapped muscle. In the proximal part of the latissimus dorsi muscle, the type I fibres comprised 68-80% in all three patients, whereas peroperatively type I fibres comprised 17-30% indicating significant but not complete transformation. Transformation in the latissimus dorsi muscle as a whole appeared to be inhomogeneous, with type I fibres ranging from 10-80%. An extensive amount of muscle fibre appeared to be replaced by fatty tissue (10%-50%). This occurred at random and resulted in complete loss of muscle structure. A significant increase in the density of small arteries was observed in the latissimus dorsi after transformation. CONCLUSIONS: In these patients, muscle fibre type transformation was not as complete as that observed in animal experiments, and was accompanied by loss of muscle viability. The stimulation current in the latissimus dorsi muscle appeared not to be the direct cause of local tissue lipomatosis or collagen deposition.

Aged↗

PubMed1997

Configuration of unipolar atrial electrograms during electrically induced atrial fibrillation in humans.

BACKGROUND: During atrial fibrillation (AF), the atrium is activated by multiple wavelets that continuously change in size and direction. The aim of this study was to correlate the temporal variation in AF electrogram configuration with the varying spatial patterns of activation. METHODS AND RESULTS: In a group of 25 Wolff-Parkinson-White patients undergoing cardiac surgery, the free wall of the right atrium was mapped (244 points) during electrically induced AF. The unipolar electrograms recorded during 4 seconds of AF were classified into four categories: (1) single deflections, (2) short-double potentials, (3) long-double potentials, and (4) fragmented potentials. The proportion of these four types of electrograms during AF was as follows: singles, 77 +/- 12%; short-doubles, 7 +/- 3%; long-doubles, 10 +/- 7%; and fragmented, 6 +/- 4%. Electrogram morphology was an indicator for rapid uniform conduction (single potentials; positive predictive value [PPV] of 0.96), collision (short-double potentials; PPV of 0.33), conduction block (long-double potentials; PPV of 0.84), and pivoting points or slow conduction (fragmented potentials; PPV of 0.87). In type I, II, and III AF, the proportion of long-double potentials was 4 +/- 2%, 12 +/- 3%, and 18 +/- 7% (P < .05); the proportion of fragmented complexes was 2 +/- 2%, 6 +/- 3%, and 10 +/- 4% (P < .05), respectively. During electrically induced and self-terminating episodes of AF, no preferential anatomic sites for double or fragmented potentials were found in the right atrium. CONCLUSIONS: The morphology of single unipolar electrograms during AF reflects the occurrence of various specific patterns of conduction. This might be used to differentiate between different types of AF and to identify regions with structural conduction disturbances involved in perpetuation of chronic AF.

Adolescent↗

PubMed1996

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.

Adult↗

PubMed1996

Single injection thermodilution. A flow-corrected method.

BACKGROUND: Application of the Stewart-Hamilton equation in the thermodilution technique requires flow to be constant. In patients in whom ventilation of the lungs is controlled, flow modulations may occur leading to large errors in the estimation of mean cardiac output. METHODS: To eliminate these errors, a modified equation was developed. The resulting flow-corrected equation needs an additional measure of the relative changes of blood flow during the period of the dilution curve. Relative flow was computed from the pulmonary artery pressure with use of the pulse contour method. Measurements were obtained in 16 patients undergoing elective coronary artery bypass surgery. In 11 patients (group A), pulmonary artery pressure was measured with a catheter tip transducer, in a partially overlapping group of 11 patients (group B), it was measured with a fluid-filled system. For reference cardiac output we used the proven method of four uncorrected thermodilution estimates equally spread over the ventilatory cycle. RESULTS: A total of 208 cardiac output estimates was obtained in group A, and 228 in group B. In group B, 48 estimates could not be corrected because of insufficient pulmonary artery pressure waveform quality from the fluid-filled system. Individual uncorrected Stewart-Hamilton estimates showed a large variability with respect to their mean. In group A, mean cardiac output was 5.01 l/min with a standard deviation of 0.53 l/min, or 10.6%. After flow correction, this scatter decreased to 5.0% (P < 0.0001). With no bias, the corresponding limits of agreement decreased from +/- 1.06 to +/- 0.5 l/min after flow correction. In group B, the scatter decreased similarly and the limits of agreement also became +/- 0.5 l/min after flow correction. CONCLUSION: It was concluded that a single thermodilution cardiac output estimate using the flow-corrected equation is clinically feasible. This is obtained at the cost of a more complex computation and an extra pressure measurement, which often is already available. With this technique it is possible to reduce the fluid load to the patient considerably.

Adult↗

PubMed1995

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.

Cardiopulmonary Bypass↗

PubMed1994

High-density mapping of electrically induced atrial fibrillation in humans.

BACKGROUND: Mapping studies in animals have suggested that atrial fibrillation (AF) is based on multiple reentering wavelets. Little information is available about the patterns of activation during AF in humans. The objective of the present study was to reconstruct and classify the patterns of human right atrial (RA) activation during electrically induced AF. METHODS AND RESULTS: AF was induced by rapid atrial pacing in 25 patients with Wolff-Parkinson-White syndrome undergoing surgery for interruption of their accessory pathway(s). The free wall of the RA was mapped using a spoon-shaped electrode containing 244 unipolar electrodes. The activation of the RA during AF showed large interindividual differences. Based on the complexity of atrial activation, three types of AF were defined. In type I (40% of patients), single broad wave fronts propagated uniformly across the RA. Type II (32%) was characterized by one or two nonuniformly conducting wavelets, whereas in type III (28%), activation of the RA was highly fragmented and showed three or more different wavelets that frequently changed their direction of propagation as a result of numerous arcs of functional conduction block. There were significant differences (P < .05) among the three types of AF in median intervals (174 +/- 28, 150 +/- 14, and 136 +/- 16 milliseconds), variation in AF intervals (P5-95) (54 +/- 25, 94 +/- 21, and 104 +/- 22 milliseconds), incidence of electrical inactivity (42 +/- 11%, 21 +/- 4%, and 8 +/- 4%) and reentry (3 +/- 7%, 36 +/- 28%, and 99 +/- 36%), and average conduction velocity during AF (61 +/- 6, 54 +/- 4, and 38 +/- 10 cm/s). CONCLUSIONS: During pacing-induced AF in humans, the RA is activated by one or multiple wavelets propagating in different directions. Three types of RA activation during AF were identified. From type I to type III, the frequency and irregularity of AF increased, and the incidence of continuous electrical activity and reentry became higher. These various types of AF in humans appear to be characterized by different numbers and dimensions of the intra-atrial reentrant circuits.

Adult↗

PubMed1993

[Double supraventricular tachycardia and its surgical treatment].

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.

Adult↗

PubMed1993

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.

Animals↗

PubMed1993

A new stimulation protocol for cardiac assist using the latissimus dorsi muscle.

When treating severe cardiac failure with dynamic cardiomyoplasty, knowledge about the optimal way of stimulating the latissimus dorsi (LD) muscle is of obvious importance. We evaluated a new stimulation protocol in four goats using in situ electrical stimulation of the left LD muscle. Stimulation was started using a burst of two pulses with an interpulse interval of 100 msec for 50 bursts/min. The number of pulses was increased every 2 weeks concomitant with a decrease in interpulse interval. This resulted after 12 weeks in 60 bursts/min using bursts of six pulses with an interpulse interval of 20 msec after 12 weeks. Force measurements, which were done every 2 weeks, showed an early decrease in contraction and relaxation speed as reflected in the ripple (= interstimulus amplitude/peak force amplitude measured at 10 Hz). Fatigue resistance increased significantly within 4 weeks of conditioning as indicated by preservation of force, positive dF/dt, and negative dF/dt. Full preservation of these variables was seen even during a 1-hour fatigue test at the end of the conditioning period. Skeletal muscle enzyme activity as an indicator of muscle damage showed a significant rise in creatine kinase enzyme activity only on the first day following the start of LD stimulation. LD muscle biopsies revealed almost complete transformation to type I muscle fibers with a significant increase in capillary/fiber ratio when compared to the nonstimulated LD muscle. However, some biopsies, in particular near the electrodes, did show some signs of skeletal muscle damage. Contraction characteristics of the fully transformed LD muscles were tested by increasing the number of bursts of six pulses from 50/min to 100/min. Interpulse intervals of 20 and 33 msec were used. These tests revealed that maximal force, positive dF/dt, and negative dF/dt was reached with 50 bursts/min using a six pulse burst with interpulse intervals of 20 msec.

Animals↗

PubMed1992

Adaptation of energy metabolism of canine latissimus dorsi muscle in response to chronic electrical stimulation.

Transformation of the latissimus dorsi (LD) muscle from a fast-twitch, fatigue-prone to a fatigue-resistant ("heart-like") muscle, necessary to allow its application in cardiac assist devices, can be induced by chronic electrical stimulation. In adult dogs we studied the nature and time course of myofibrillar and metabolic adaptations in the LD muscle when exposed in situ to 24 weeks of continuous electrical stimulation. In addition, the metabolic properties of the stimulated muscle were compared with those of canine cardiac muscle. The proportion of immunohistochemically identified type I fibres increased on stimulation from 28% to 80%, while that of type II fibres decreased from 69% to 16%. Fibres of intermediate type (IIC and IC) appeared transiently; the highest levels were found between 4 and 8 weeks of stimulation. The activities of fructose-6-phosphate kinase and lactate dehydrogenase (LDH), which before stimulation were similar to those in heart, decreased to 18% and 34% of their initial values respectively. However, the LDH isozyme pattern changed towards that typical for cardiac muscle. These changes indicate a markedly decreased flux capacity through the glycolytic pathway which, however, is directed more towards the oxidative conversion of substrates. The mitochondrial capacity (maximal palmitate oxidation and pyruvate dehydrogenase complex activities) of the muscle did not change and remained at a level less than half of that of cardiac ventricular muscle. Contents of adenine nucleotides and endogenous substrates were maintained during stimulation. No further changes in the observed adaptations occurred after week 12 of stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adaptation, Physiological↗

PubMed1992

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.

Adult↗

PubMed1992

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.

Animals↗

PubMed1992

The importance of muscle relaxation in dynamic cardiomyoplasty.

During the last decade dynamic cardiomyoplasty has been introduced as a new method to treat patients with severe heart failure. This procedure consists of the wrapping of the latissimus dorsi (LD) muscle around the heart with electrical stimulation of the muscle synchronous to cardiac contraction. The optimal pacing mode of the muscle, during the conditioning and working period of the LD muscle, is still unclear. The pace protocol, currently used worldwide, has a maximal number of muscle tetanic contractions of 100 per minute. Data are presented on the LD muscle contraction characteristics using that protocol. Both force measurements from six in situ stimulated goat LD muscles and x-ray evaluation of the movement of metallic clips on wrapped LD muscles in two patients were used. Results demonstrate that LD muscle force is well maintained at the maximal rate of 100 contractions per minute but relaxation is severely hampered. This may lead to diminished support of the failing heart and damage of the wrapped muscle. A pacing protocol is proposed using a lower maximal stimulation rate.

Animals↗

PubMed1992

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.

Adaptation, Physiological↗

PubMed1992

Systemic to pulmonary vascular malformation.

A case is reported of life-threatening haemoptysis as a result of an anomalous communication between a bronchial artery and pulmonary vein, demonstrated by angiography. The patient recovered following bilobectomy of the right lower and middle lobes. When a systemic artery is involved in an arteriovenous malformation of the lung, haemodynamics are different compared with those present in malformations fed by the pulmonary artery. This implicates other clinical features, options for surgical intervention and prognosis. In reviewing the literature, a relationship with Rendu-Osler-Weber disease is absent in these specific malformations.

Adult↗

PubMed1991

What is the ideal pulse frequency for skeletal muscle stimulation after cardiomyoplasty?

Routinely the latissimus dorsi (LD) muscle is stimulated with bursts of pulses at 30 pulses/sec after cardiomyoplasty to assist the failing heart. At a lower pulse frequency the contractile force decreases and at higher frequencies the energy demand of the pacemaker increases rapidly. We investigated the effect of the stimulus frequency variation on contractile force in untrained LD muscles and in muscles after 12 weeks of continuous cyclic electrical stimulation. In six dogs, two electrodes (Medtronic SP5528) were implanted in the left LD muscle together with an Itrel muscle stimulator. The LD muscle was stimulated with 30 pulses/sec in bursts to deliver initially 30 and after 10 weeks 80 contractions per minute. Both before and after training of the LD muscle maximum force was observed by stimulating with a frequency of 36 to 130 pulses/sec in a burst. However, training induced a shift in the steep part of the force-frequency relation to lower frequencies. In particular, at 15 pulses/sec 60% of the maximal force was obtained in contrast to 40% before training. A fatigue test of 8 minutes duration was performed specified by 100 bursts/min and a burst duration of 0.25 sec at pulse frequencies of 30, 36, 50, and 85 pulses/sec. The contractile force decreased significantly during the course of the test at all frequencies. However, the force obtained with 30 pulses/sec stimulation was lower during the initial phase and approximately 10% higher at the end of the fatigue test as compared to 36, 50, and 85 pulses/sec stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1991

A new method to select stimulus strength after cardiomyoplasty.

At present, there is no technique available for the determination of optimal stimulus strength in patients after cardiomyoplasty. To stimulate the latissimus dorsi (LD) muscle, we implanted Itrel stimulators in two goats and cardiomyostimulators in three goats following the routine cardiomyoplasty procedure. During the following 3 months, these LD muscles were conditioned at 2.5-4.0 volts (V). After conditioning, LD muscle shortening was measured on x-ray films using the distance between two stimulation electrodes as references. LD muscle shortening increased rapidly at higher stimulus strength and reached 13% +/- 2% at 2.0 V. Shortening was calculated in one patient at 4, 6, and 9 weeks following surgery. The increase in the number of pulses per burst (2, 3, and 6, respectively) had a positive effect on muscle shortening between the two stimulation electrodes (10%, 14%, and 20%, respectively). Also, muscle shortening was measured between two clips attached to the distal part of the LD muscle. Muscle shortening in the area wrapped around the left ventricle was 15% after 9 weeks. In a second patient, shortening between the electrodes was 16% at 14 months after surgery, and distal muscle shortening was 11%. We concluded that optimal stimulation after cardiomyoplasty could be detected more accurately by measurement of LD muscle shortening using the stimulation electrodes or surgical clips as markers.

Animals↗