Biomedical subjects

Raymond Tukkie

Publications and source records attributed to Raymond Tukkie.

12 recordsLinked to original sources

PubMed2005

Implantable cardioverter defibrillator implantation in children in The Netherlands.

UNLABELLED: To evaluate the indications, underlying cardiac disorders, efficacy and complications involved with implantable cardioverter-defibrillators (ICDs) in paediatric patients in The Netherlands, the records of all patients aged 18 years or younger who underwent ICD placement were reviewed retrospectively. Between January 1995 and September 2002, 23 patients (11 males, 12 females; median age 12 years, range 6 months to 16 years) underwent ICD implantation. The ICD was implanted for aborted sudden cardiac death ( n = 14), syncope ( n = 5) or for primary prevention of sudden cardiac death ( n = 4). Underlying cardiac disorders were electrical diseases ( n = 16), hypertrophic or dilated cardiomyopathy ( n = 4) and congenital cardiac malformations ( n = 3). Five patients had an epicardially placed ICD, while 18 underwent a transvenous approach. The generator was placed in an abdominal position in eight patients, whereas it was placed in the subpectoral region in 15. There was no early mortality. Median hospital stay was 5 days (range 2-30 days). Median follow-up time was 29 months (range 1 month to 7 years). Seven patients experienced an inappropriate shock after a median period of 7 months; five patients an appropriate shock after a median period of 3 months. The reasons for inappropriate shock were supraventricular tachycardia ( n = 1), sinus tachycardia ( n = 4) or T-wave sensing (n = 2). One patient with malignant long QT syndrome died of intractable arrhythmias and irreversible cardiomyopathy. Generator replacement was necessary in four patients after 28, 44, 51 and 54 months respectively. CONCLUSION: Implantable cardioverter-defibrillator implantation in paediatric patients is a safe procedure with a good medium-term outcome. The most serious problem is the occurrence of a significant number of inappropriate shocks.

Adolescent↗

PubMed2005

Varying the heart rate response to dynamic exercise in pacemaker-dependent subjects: effects on cardiac output and cerebral blood velocity.

Cerebral blood flow increases upon the transition from rest to moderate exercise, but becomes affected when the ability to raise CO (cardiac output) is limited. HR (heart rate) is considered to contribute significantly to the increase in CO in the early stages of dynamic exercise. The aim of the present study was to test whether manipulation of the HR response in patients dependent on permanent rate-responsive ventricular pacing contributes to the increase in CO, MCA V(mean) [mean MCA (middle cerebral artery) velocity] and work capacity during exercise. The effect of setting the pacemaker to DSS ('default' sensor setting) compared with OSS ('optimized' sensor setting) on blood pressure, CO, SV (stroke volume) and MCA V(mean) was evaluated during ergometry cycling. From rest to exercise at 75 W, the rise in HR in OSS [from 73 (65-87) to 116 (73-152) beats/min; P<0.05] compared with DSS [70 (60-76) to 97 (67-117) beats/min; P<0.05] was larger. There was an increase in SV during exercise with DSS, but not with OSS, such that, at all workloads, SVs were greater during DSS than OSS. The slope of the HR-CO relationship was larger with DSS than OSS (P<0.05). From rest to exercise, MCA V(sys) (systolic MCA velocity) increased in OSS and DSS, and MCA V(dias) (diastolic MCA velocity) was reduced with DSS. No changes were observed in MCA V(mean). Manipulation of the pacemaker setting had no effect on the maximal workload [133 (100-225) W in OSS compared with 129 (75-200) W in DSS]. The results indicate that, in pacemaker-dependent subjects with complete heart block and preserved myocardial function, enhancing the HR response to exercise neither augments CO by a proportional offset of the exercise-induced increase in SV nor improves cerebral perfusion.

Aged↗

PubMed2005

Individual optimization of pacing sensors improves exercise capacity without influencing quality of life.

INTRODUCTION: Programmable pacemaker sensor features are frequently used in default setting. Limited data are available about the effect of sensor optimization on exercise capacity and quality of life (QOL). Influence of individual optimization of sensors on QOL and exercise tolerance was investigated in a randomized, single blind study in patients with VVIR, DDDR, or AAIR pacemakers. METHODS: Patients with > or =75% pacing were randomized to optimized sensor settings (OSS) or default sensor setting (DSS). Standardized optimization was performed using three different exercise tests. QOL questionnaires (QOL-q: Hacettepe, Karolinska, and RAND-36) were used for evaluation of the sensor optimization. One month before and after optimization, exercise capacity using chronotropic assessment exercise protocol and the three QOL-q were assessed. RESULTS: Fifty-four patients (26 male, 28 female) with a mean age of 65 +/- 16 years were enrolled in the study. In each group (OSS and DSS) 27 patients were included. One month after sensor optimization, the achieved maximal heart rate (HR) and metabolic workload (METS) were significantly higher in OSS when compared with DSS (124 +/- 28 bpm vs 108 +/- 20 bpm, P = 0.036; 7.3 +/- 4 METS vs 4.9 +/- 4 METS, P = 0.045). Highest HR and METS were achieved in patients with pacemakers with accessible sensor algorithms. In patients with automatic slope settings (33%), exercise capacity did not improve after sensor optimization. QOL did not improve in OSS compared with DSS. CONCLUSION: After 1 month of individual optimization of rate response pacemakers, exercise capacity was improved and maximum HR increased, although QOL remained unchanged. Accessible pacemaker sensor algorithms are mandatory for individual optimization.

Adult↗

PubMed2005

Cardiac resynchronization induces favorable neurohumoral changes.

AIM: The aim of this article is to examine whether cardiac resynchronization therapy (CRT) induces improvements in the neurohumoral system. METHODS AND RESULTS: Thirteen patients with HF (left ventricular (LV) ejection fraction <35%) were included. Before and after 6 months of CRT, myocardial (123)I-metaiodobenzylguanidine ((123)I-MIBG) uptake indices, used as an index of neural norepinephrine reuptake and retention, and brain natriuretic peptide (BNP) levels, used as an index of LV end-diastolic pressure, NYHA classification and echocardiographic indices were assessed. Six months of CRT resulted in significant improvement in (1) NYHA classification and reduction in QRS width (P < 0.001), (2) decrease of LV end-diastolic diameter (P = 0.005), LV end-systolic diameter (P = 0.005), septal to lateral delay (P = 0.01) and mitral regurgitation (MR, P = 0.04), (3) delayed (123)I-MIBG heart/mediastinum ratios improved (P = 0.03) and (123)I-MIBG washout decreased (P = 0.001), and (4) BNP levels decreased (P = 0.001). CONCLUSIONS: Parallel to significant functional improvement and echocardiographic reverse remodeling and resynchronization, our data indicate that CRT induces favorable changes in the neurohumoral system.

3-Iodobenzylguanidine↗

PubMed2004

Delay in right ventricular activation contributes to Brugada syndrome.

BACKGROUND: Although Brugada syndrome revolves around reduced net depolarizing force, the electrophysiological mechanisms of its defining features (right precordial ST-segment elevation and ventricular tachyarrhythmias) remain unresolved. Two proposed mechanisms are (1) right ventricular (RV) conduction delay and (2) selective and significant RV subepicardial action potential shortening. Both mechanisms must cause disparate contractile changes: delay in RV contraction and reduction of contractile force, respectively. We aimed to establish the electrophysiological mechanism of Brugada syndrome by studying the timing and force of RV contraction. METHODS AND RESULTS: Using tissue Doppler echocardiography, we studied how these contractile variables change on induction of the characteristic ST-segment changes of Brugada syndrome by flecainide challenge. Accordingly, we studied patients in whom flecainide induced these changes (inducible) and those in whom these changes were not induced (control). We found that (1) the occurrence of a positive response (coved-type ST elevation) after flecainide coincides with delay in the onset of contraction between the RV and left ventricle (LV); (2) the extent of contraction delay between RV and LV correlates with the magnitude of ST elevation; and (3) RV ejection time (duration of RV ejection phase) shortens as the Brugada ECG pattern emerges. CONCLUSIONS: These results indicate that both proposed mechanisms of Brugada syndrome may be operative.

Action Potentials↗

PubMed2004

The vascular response induced by transmyocardial laser revascularization is determined by the size of the channel scar: Results of CO2, holmium and excimer lasers.

BACKGROUND AND OBJECTIVES: To investigate the angiogenic effect of CO2, Ho:YSGG, and XeCl excimer TMLR in a rat model with morphologic characteristics of chronic myocardial ischemia. STUDY DESIGN/MATERIALS AND METHODS: Two channels (200-320 microm) were created per rat heart. After 14 days, vessel numbers and densities in and around laser scars were assessed. RESULTS: Capillary densities in the laser scars were equal between the three lasers ( approximately 130 vessels/mm2) but much lower than in control areas ( approximately 2,100 vessels/mm2). Vessel densities excluding capillaries were significantly higher in Ho:YSGG and CO2 scars compared to excimer scars, while only Ho:YSGG scars contained significantly more large vessels (diameter > or = 20 microm) than control areas. Only rarely, extension of vascular growth into adjacent myocardium was observed in any of the three groups. CONCLUSIONS: These results indicate that the angiogenic response following TMLR is limited to the channel scar and related to the scar size rather than the specific laser type.

Animals↗

PubMed2004

Transmyocardial revascularization using an XeCl excimer laser: results of a randomized trial.

BACKGROUND: CO2 and holmium:yttrium aluminum garnet (YAG) transmyocardial laser revascularization (TMLR) are used to treat patients with refractory angina. A randomized trial to investigate the efficacy and safety of XeCl excimer TMLR was performed. METHODS: Thirty patients with refractory angina were randomized in pairs to excimer TMLR or maximal medication. We assessed angina, quality of life (QOL), exercise time, myocardial perfusion, and ventricular wall motion at base line and at 3, 6, and 12 months after TMLR. RESULTS: TMLR patients manifested a significantly better outcome with respect to angina class and quality of life. One TMLR patient died perioperatively versus none in the control group. After TMLR angina decreased from class 3.8 +/- 0.4 at base line to 1.9 +/- 0.9 at 12 months versus 3.9 +/- 0.3 to 3.7 +/- 0.6 in the control group, respectively (p = 0.000001). At 12 months a decrease of greater than or equal to two angina classes was indicated in 11 out of 14 TMLR patients versus none in the control group (p = 0.00001). Improved myocardial perfusion or exercise time was not indicated despite a small decrease in reversible wall motion abnormality score. CONCLUSIONS: Excimer TMLR significantly relieves angina and improves QOL without evidence of improved cardiac perfusion or function.

Adrenergic beta-Antagonists↗

PubMed2004

Cardiac denervation after clinical transmyocardial laser revascularization: short-term and long-term iodine 123-labeled meta-iodobenzylguanide scintigraphic evidence.

OBJECTIVES: This study was designed to investigate whether transmyocardial laser revascularization induces myocardial denervation and to correlate this with myocardial perfusion and clinical status. METHODS: Transmyocardial laser revascularization was performed with a Holmium:YAG (n = 3) or xenon chloride excimer laser (n = 5). Preoperative and postoperative iodine 123-labeled meta-iodobenzylguanide SPECT scintigraphy to assess cardiac innervation and perfusion scintigraphy were also performed. Furthermore, New York Heart Association functional angina class and quality of life were assessed. RESULTS: In all patients postoperative iodine 123-labeled meta-iodobenzylguanide SPECT showed significantly decreased uptake and therefore sympathetic myocardial denervation at up to 16 months' follow-up (average preoperative and postoperative summed defect scores of 14.8 +/- 5.3 and 24.5 +/- 4.2, respectively; P =.00005). In 86% of segments, the decreased meta-iodobenzylguanide uptake could be correlated to the treated area. In all patients angina was reduced by 2 or more classes at 12 months' follow-up, and quality of life improved significantly. CONCLUSIONS: Transmyocardial laser revascularization-induced improvement of angina and quality of life can be explained by destruction of nociceptors or cardiac neural pathways, changing the perception of anginal pain.

3-Iodobenzylguanidine↗

PubMed2004

Undersensing of VF in a patient with optimal R wave sensing during sinus rhythm.

We describe a case of potentially fatal undersensing of VF by a third generation ICD with predetermined automatic gain control. In this patient, ventricular sensing was optimal, as R wave amplitudes during sinus rhythm were at least 16 mV. Cyclical, high amplitude signals during VF elevated the sensing floor to such an extent that complete undersensing of subsequent lower amplitude local electrograms occurred. This led to bradypacing and complete ICD therapy failure. Therefore, high R wave amplitudes during sinus rhythm do not warrant flawless sensing during VF.

Aged↗

PubMed2004

Direct comparison of a contractility and activity pacemaker sensor during treadmill exercise testing.

There are limited data about the chronotropic capacity of the peak endocardial acceleration (PEA) sensor. This study directly compared the chronotropic function from the PEA and the activity (ACT) sensor. The study included 18 patients (age 73 +/- 7 years) with > or = 75% pacemaker-driven heart rate (HR) and a PEA sensor and 11 healthy controls (age 67 +/- 7 years) underwent a chronotropic assessment exercise protocol (CAEP) exercise test with the pacemaker patients in VVIR mode after programming the sensors in the default setting with adjustment of the upper sensor rate as an age related maximum value (220-age). The ACT sensor was externally strapped on the thorax. Achieved exercise duration for the patients and controls was, respectively, 9.2 +/- 3 vs 18.4 +/- 4 minutes (P <0.001). The maximal achieved HR with the PEA sensor was 124 +/- 25 beats/min, versus the ACT with 140 +/- 23, versus the controls with 153 +/- 26 beats/min (P <0.001 between the groups). For the PEA, ACT, and controls, the time to peak HR was, respectively, 11 +/- 3, 7 +/- 3.6, and 18 +/- 4 (P <0.001 between groups) and HR after 10 minutes recovery was, respectively, 80 +/- 20, 65 +/- 15, and 82 +/- 4 beats/min (P <0.001 between groups). The PEA sensor functions hypochonotroop during exercise programmed as a single sensor system. It is, therefore, preferable to combine the PEA sensor with an activity-based sensor in a dual sensor system. Although both groups had normal left ventricular functions, the exercise capacity of pacemaker patients is significantly lower than in the controls.

Aged↗

PubMed2003

Improved quality of life after XeCl excimer transmyocardial laser revascularization: results of a randomized trial.

BACKGROUND AND OBJECTIVES: We assessed quality of life (QOL) after XeCl transmyocardial laser revascularization (TMLR). STUDY DESIGN/MATERIALS AND METHODS: Thirty patients were randomized to receive XeCl excimer TMLR or optimal cardiac medication (controls). QOL was assessed at baseline, 1, 3, 6, and 12 months using three different questionnaires: The Medical Outcomes Study Short Form-24 (MOS SF-24), the EuroQol Standardized Questionnaire, and the Seattle Angina Questionnaire (SAQ). The primary outcome measure was the change in score between baseline and 12 months. RESULTS: TMLR patients scored significantly better compared to controls in the MOS SF-24 social functioning, energy, general health, and bodily pain domains, in the EuroQol usual activity domain and the EuroQol Visual Analogue Scale, and in the SAQ physical limitation, angina frequency and disease perception domains. CONCLUSIONS: QOL significantly improved after XeCl excimer TMLR compared to medication. These results are similar to reported improvements in QOL after CO(2) and Ho:YAG TMLR.

Aged↗

PubMed2002

35 years of experimental research in transmyocardial revascularization: what have we learned?

In the past 35 years many experimental studies have been performed to investigate the revascularization potential of transmyocardial revascularization and the possible working mechanisms underlying the observed clinical improvement in angina pectoris after this treatment. In this review of the experimental literature, the various methods that have been used to create transmyocardial channels and the most supported hypotheses on the working mechanism (channel patency, angiogenesis and myocardial denervation) are discussed and evaluated.

Animals↗