Göran Källner

Release and effects of calcitonin gene-related peptide in myocardial ischaemia

1. Low pH and lactic acid perfusion evoke a reproducible, and concentration-dependent outflow of CGRP from the isolated heart. 2. PGI2 causes outflow of CGRP from the isolated heart. Furthermore, low pH perfusion causes release of PGI2, and cyclo-oxygenase inhibition attenuates not only this release of PGI2, but also the outflow of CGRP that is evoked by low pH perfusion, indicating that a portion of the C-fibre activation exerted by low pH is mediated by PGI2. 3. The outflow of CGRP that is caused by low pH but not that evoked by capsaicin or PGI2 is dependent on the endothelium, whereas the vasodilating effect of CGRP is preserved after removal of the endothelium. 4. TTX attenuates release of CGRP caused by low concentrations of capsaicin, indicating that an axon reflex mechanism in the peripheral endings of C-fibre afferents can augment local outflow of CGRP. 5. Outflow of CGRP evoked by low pH and capsaicin have common features, such as sensitivity to RR and CPZ. N-type calcium channels are involved in release of CGRP by both stimuli. 6. In the coronary vasculature, exogenous CGRP augmented post-occlusive hyperaemia. 7. In the pig in vivo, CGRP causes marked dose-dependent reduction of systemic vascular resistance. This effect of CGRP was partly reduced by CGRP(8-37). 8. Capsaicin pretreatment resulted in lower myocardial levels of CGRP, and ischaemic myocardium had lower content of CGRP than non-ischaemic areas. Capsaicin-treated animals had larger myocardial infarctions, possibly due to depletion of CGRP. When endogenous stores of CGRP were intact, administration of additional CGRP to the ischaemic myocardium had no cardioprotective effect. 9. In patients undergoing CABG without CPB, 10-20 minutes of local ischaemia (as evidenced by a net production of lactate) was associated with increased levels of CGRP in coronary sinus blood. 10. Based on the present findings it may therefore be suggested that local cardiac CGRP-release from capsaicin-sensitive C-fibre afferents during myocardial ischaemia functions as an endogenous physiological protective response. The possibility thus exists that effects of CGRP observed in animal studies may play a role in human myocardial ischaemia.

Myocardial release of troponin T after coronary bypass surgery

The temporal changes in cardiac S-troponin T, S-creatine kinase-MB(S-CK-MB)mass and S-myoglobin were studied for 5 days after coronary bypass grafting in 70 patients. Perioperative infarction occurred in ten patients (2 Q wave, 8 non-Q wave). All three markers showed significant increase even in patients without signs of perioperative infarction. Within 8-12 hours their levels rose significantly (p < 0.001) more in the infarction than in the non-infarction cases. Troponin T and CK-MBmass both showed early (< 8-12 h) peaks in patients with perioperative infarction. CK-MBmass returned to near normal levels within 48-72 hours, whereas troponin T remained markedly increased throughout the observation. Myoglobin concentrations varied widely among the infarction cases. In the non-infarction group, troponin T and CK-MBmass (but not myoglobin) were related to the aortic cross-clamp time. Troponin T (but not CK-MBmass) remained elevated throughout the study period in patients with longer cross-clamp times. These findings may indicate continuous release from damaged myocardium in cases of perioperative infarction. Troponin T and CK-MBmass can serve as markers of perioperative infarction and troponin T may also be useful as a marker in studies on myocardial protection.

Morphological changes rather than flow-mediated dilatation in the brachial artery are better indicators of the extent and severity of coronary artery disease

Objectives The aim of this study was to examine the relationship between morphological and functional parameters of the brachial and carotid arteries and the angiographic extent and severity of coronary artery stenosis in patients with severe coronary artery disease (CAD). Design A cross-sectional study. Setting University hospital. Main outcome measures Flow-mediated dilatation (FMD), intima–media thickness (IMT) in the brachial artery and atherosclerotic wall changes in the carotid arteries were measured by B-mode high-resolution ultrasound in 58 patients who had undergone coronary angiography. Results A significant correlation was seen between the extent of coronary artery stenosis defined as the coronary angiographic score and both the mean brachial artery IMT and intima–media area (IMa; P = 0.01 and P = 0.04, respectively). There was no significant correlation between FMD and the extent of coronary artery stenosis. A significant correlation was seen between the mean carotid artery IMT and the mean brachial artery IMT (r = 0.30, P = 0.03). However, there was no significant correlation between FMD and the mean carotid artery IMT or IMa (r = 0.16, P = 0.23 and r = 0.17, P = 0.24, respectively). Conclusions Morphological but not functional parameters of the brachial artery are associated with the extent of coronary artery stenosis and atherosclerotic wall changes in the carotid arteries in patients with severe CAD. These findings indicate a potential of B-mode ultrasonography of morphological parameters in the brachial artery in the diagnostic and prognostic evaluation of patients with suspected CAD.

Transaortic approach for the Alfieri stitch

The management of associated mitral regurgitation in patients undergoing cardiac surgery is controversial. A simple, reliable, and fast repair is advantageous, especially in critically ill patients. We describe a simple method of transaortic edge-to-edge repair in patients with associated mitral regurgitation undergoing aortic valve surgery.

A Swedish consensus on the surgical treatment of concomitant atrial fibrillation

Abstract Atrial fibrillation (AF) is a common arrhythmia among patients scheduled for open heart surgery and is associated with increased morbidity and mortality. According to international guidelines, symptomatic and selected asymptomatic patients should be offered concomitant surgical AF ablation in conjunction with valvular or coronary surgery. The gold standard in AF surgery is the Cox Maze III (“cut-and-sew”) procedure, with surgical incisions in both atria according to a specified pattern, in order to prevent AF reentry circuits from developing. Over 90% of patients treated with the Cox Maze III procedure are free of AF after 1 year. Recent developments in ablation technology have introduced several energy sources capable of creating nonconducting atrial wall lesions. In addition, simplified lesion patterns have been suggested, but results with these techniques have been unsatisfactory. There is a clear need for standardization in AF surgery. The Swedish Arrhythmia Surgery Group, represented by surgeons from all Swedish units for cardiothoracic surgery, has therefore reached a consensus on surgical treatment of concomitant AF. This consensus emphasizes adherence to the lesion pattern in the Cox Maze III procedure and the use of biatrial lesions in nonparoxysmal AF.

Learning what works in surgical cryoablation of atrial fibrillation: results of different application techniques and benefits of prospective follow-up

Atrial fibrillation (AF) in cardiac surgical patients is detrimental in the long perspective. Concomitant surgical ablation of AF is recommended in guidelines and performed in most centers. The article describes the experiences in a single institution with concomitant surgical argon-based cryoablation in 115 patients using three different application techniques (epicardial left atrium, endocardial left atrium, biatrial cryo-maze) and a structured local follow-up to one year postoperatively. Results showed cryoablation to be safe with few complications related to the ablation procedure and few thromboembolic events. In this study, a complete biatrial lesion set according to the classic Cox-maze III (CM III) lesion pattern yielded a higher success rate than left atrial procedures. At 12 months, patients in sinus or pacing rhythm, free of AF without antiarrhythmic drugs, were 27/39 (69%), 24/32 (74%) and 36/44 (82%) in the EpiLA, EndoLA and cryo-maze groups, respectively. A consistent prospective follow-up is essential not only for research purposes but also for assessing the local results of AF surgery in everyday practice. It may direct and develop the surgical ablation program, guide individual postoperative arrhythmia management and is needed to increase overall quality of surgical AF ablation.

The biatrial cryo-maze procedure for treatment of atrial fibrillation: A single-center experience

Abstract Objectives. The Cox-maze III procedure is the benchmark for atrial fibrillation (AF) surgery but has been replaced by surgical ablation. We evaluated our experience with biatrial cryoablation using the full Cox-maze III lesion pattern, and adhering follow-up to current guidelines. Design. Forty-three patients underwent the biatrial cryo-maze procedure as a concomitant (n = 37) or stand-alone procedure (n = 6). Mean age was 64.8 ± 9.5 years. Overall, AF was paroxysmal/persistent/permanent in 28/14/58%. Mean AF duration was 5.2 ± 6.5 years. Follow-up included prospective evaluation at 1, 3 and 12 months, long-term monitoring and transthoracic echocardiography. Results. No mortality and no complications related to the ablation procedure occurred. One patient suffered a stroke at 12 months. In the concomitant group, rhythm was sinus/pacing without AF/AF in 65/16/19% at three months, and 59/22/19% at 12 months. Five patients received new pacemakers (12%). In the stand-alone group, 5/6 (83%) patients had sinus rhythm with no AF at three and 12 months. Overall, 35/43 patients (81%) had sinus/paced rhythm at 12 months with no AF and no anti-arrhythmic drugs. Echocardiography showed satisfactory results in all patients. Conclusions. The biatrial cryo-maze procedure is safe and effective in surgical patients with concomitant AF, and could be considered for selected patients with lone AF.

The assessment of acute load and contractility changes by left ventricular pressure measurements

The aim of this study was to establish whether analysis of the left ventricular pressure waveform provides indicative information about cardiac load and contractility and to develop an algorithm for computer-based assessment of changes in these variables. In eight healthy standard breed anaesthetized open-chest pigs, a high frequency response guide-wire mounted pressure sensor was introduced into the left ventricle. Preload reduction was induced by vena cava occlusion, afterload increase by an i.v. injection of phenylephrine and increased contractility by an i.v. injection of adrenalin. Left ventricular pressure waveform analysis was performed by plotting the slope of the pressure curve during the systolic ejection period versus maximal systolic pressure. The analysis revealed characteristic changes in left ventricular pressure and pressure waveform and identified easily discernible reaction patterns in the slope versus maximal pressure plot, specific for each provocation. Analysis of the left ventricular waveform provides indicative information about loading conditions and contractility. The proposed algorithm can easily be implemented in pressure monitoring systems allowing real-time assessment and discrimination of acute changes in preload, afterload and myocardial performance.